The utilization of microalgal biomass for the production of biodiesel and bioethanol is viewed as a promising alternative to increase the offer of both biofuels in the future. In view of this, the autotrophic growth of the green microalga Chlorella vulgaris in a flat-plate photobioreactor was evaluated along with physiological characteristics, such as lipid and carbohydrate composition, and auxiliary parameters of the cultivation using response surface methodology (RSM). Mean biomass productivities of up to 0.262 +/- 0.006 g L-1 day(-1) were obtained with maximum light intensity and intermediate CO2 concentrations and the microalgal biomass averaged carbohydrate and lipid contents of 8\% and 32\% respectively. The light flux supplied to the cultivations and the amount of CO2 in the feed gas are variables with significant effect on the mean biomass productivity of the microalgae and help estimate the maximum final biomass concentration possible to be obtained. The behavior of associated parameters, such as increase in medium pH and O-2 evolution, was measured and both varied according to different cultivation conditions.
Previously, lactic acid (LA) hydrolysis has been applied in xylo-oligosaccharides (XOS) production from poplar. However, the impact of the pH value of LA on the production of XOS was unclear. In this study, the delignified poplar was prepared by hydrogen peroxide-acetic acid pretreatment of poplar, and lignin removal reached 84.1\%. LA with different pH values (2.0-5.0) was applied in XOS and monosaccharides production from delignified poplar, and the xylanase hydrolysis of delignified poplar for XOS production was used for comparison. Results demonstrated that a XOS yield of 18.5\% was acquired from delignified poplar by xylanase hydrolysis. However, a high XOS yield of 44.1\% was acquired from delignified poplar by LA hydrolysis at pH 2.5, an increase of 20.2\% when compared with LA hydrolysis with original pH value (2.0). Xylanase hydrolysis of the LA hydrolysates increased the XOS yield by 38.3\% and finally, a total XOS yield of 61.0\% was obtained, which was the highest XOS yield from poplar in the previous reports. Additionally, a satisfied glucose yield of 89.4\% was acquired from poplar residue by cellulase. This work confirmed the high efficiency of the combination of pHcontrolled LA hydrolysis and xylanase hydrolysis in XOS production from poplar.
This work contributes to the scarce information regarding the use of fixed-growth reactors for two-stage anaerobic digestion. Two up-flow continuous packed-bed reactors connected in series were evaluated during 335 days for tequila vinasses treatment. Different organic loading rates (OLRs) were evaluated ranging from 7.7 to 29 g-COD L-1 d(-1) for the acidogenic reactor (A-reactor) and from 2.7 to 12 g-COD L-1 d(-1) for the methanogenic one (M-reactor). Results showed that the A-reactor remained stable under OLRs up to 19.4 g-COD L-1 d(-1), while fermentative products (volatile fatty acids, VFAs) were effectively transformed to biogas in the M-reactor (similar to 87\% of the theoretical methane yield). A higher OLR (29.0 g-COD L-1 d(-1)) in the A-reactor resulted in an overproduction of VFAs (7.1 g-acetic acid L-1), which decreased the diversity and evenness of methanogenic populations in the M-reactor. Overall, similar methane yields to those previously reported for tequila vinasses were obtained but at higher OLRs. (C) 2018 Elsevier B.V. All rights reserved.
Pretreatment technologies are proposed to break the crosslinked biomass matrix and facilitate bioconversion processes or chemical agent attacks in reaction schemes. However, most of the pretreatments are studied in single-step schemes, limiting the integral valorization of the feedstock composition. Therefore, sequential pretreatments could maximize this valorization by isolating more biomass fractions or removing unwanted compounds. This work focuses on proposing and assessing different sequential pretreatments for the isolation of lignocellulosic fractions. After a pretreatment screening, ten technical and economic indicators were assessed through a heuristic analysis. Data from the literature were used to evaluate five operational indicators and as the specification of processing units in simulation schemes to also evaluate five techno-energetic and economic indicators. As a main result, it was concluded that the sequential pretreatments of dilute acid (DA) with wet air oxidation (WAO) could be the most optimal for cellulose isolation, steam explosion (SE) with DA for hemicellulose fractionation, and DA with kraft process for lignin solubilization. Additionally, the DA and WAO sequence may be the most efficient in biorefinery designs since it maximizes biomass fractionation, producing two hydrolyzed liquors, one rich in sugars and the other in soluble lignin, as well as a cellulose-rich solid.
Generation of specific xylooligosaccharides (XOS) is attractive to the pharmaceutical and food industries due to the importance of their structure upon their application. This study used chemometrics to develop a comprehensive computational modelling set to predict the parameters maximising the generation of the desired XOS during enzymatic hydrolysis. The evaluated parameters included pH, temperature, substrate concentration, enzyme dosage and reaction time. A Box-Behnken design was combined with response surface methodology to develop the models. High-performance anion-exchange chromatography coupled with triple-quadrupole mass spectrometry (HPAEC-QqQ-MS) allowed the identification of 22 XOS within beechwood xylan hydrolysates. These data were used to validate the developed models and demonstrated their accuracy in predicting the parameters maximising the generation of the desired XOS. The maximum yields for X2-X6 were 314.2 +/- 1.2, 76.6 +/- 4.5, 38.4 +/- 0.4, 17.8 +/- 0.7, and 5.3 +/- 0.2 mg/g xylan, respectively. These values map closely to the model predicted values 311.7, 92.6, 43.0, 16.3, and 4.9 mg/g xylan, respectively.
Hypothesis: Hydrophobic oleic acid/water interfaces are negatively charged. Hence, the use of cationic nanocelluloses as stabilizers of Pickering emulsions could improve the colloidal stability due to the electrostatic complexation at the oil-water interface. Experiments: Two cationic nanofibrillated cellulose (cNFCs) with two degrees of substitution were prepared and used as stabilizers of Pickering emulsions. The adsorption of cNFCs at the oil: water interface was evaluated by interfacial tension, atomic force microscopy, and centrifugation measurements. LUMiSizer and optical microscopy techniques were used to analyze the colloidal stability and oil droplets morphology, respectively. Besides, the rheological behavior of the continuous aqueous phase was determined through flow and stress sweep curves. Finally, the dispersion of cNFCs in a diluted emulsion was visualized by cryogenic transmission electron microscopy (cryo-TEM). Findings: Cationic NFCs were more efficient in partitioning to the oil:water interface compared to their anionic analogous, oCNF. The electrostatic attraction between the positively charged trimethylammonium groups and the negatively charged deprotonated oleic acid reduced the interfacial tension and improved the colloidal stability of O/W Pickering emulsions. cNFCs dispersed in the aqueous phase were found to increase the viscosity, decelerating the oil drops coalescence. Therefore, the stabilization of cNFCs Pickering emulsions had a synergistic effect from the electrostatic complexation at the liquid-liquid interface and network formation in the aqueous phase, as visualized by cryo-TEM. (C) 2020 Elsevier Inc. All rights reserved.
The extensive use of fossil-based plastics has raised concerns regarding the depletion of fossil resources and the deterioration of the environment. Phenyllactic acid (PhLA), fermented from renewable resources, could be used to produce high-performance bio-plastics able to replace the fossil-based engineering plastics (FBEPs) in many applications. In order to evaluate the environmental performance of poly(PhLA) produced from sweet sorghum, a cradle-to-factory-gate life cycle assessment was performed for two impact categories, namely fossil energy consumption and greenhouse gas (GHG) emissions per kilogram of poly(PhLA). These two impact categories were compared with those of the FBEPs, and with those of the bio-based polylactides (PLA) and poly(hydroxyalkanoate) (PHA). The fossil energy consumption for poly(PhLA) is 24.2 MJ/kg, which is lower than that of the FBEPs and the bio-based PLA and PHA. However, the GHG emissions are 6.2 kg CO2 eq/kg using the current technology; these are higher than those of the FBEPs and bio-based PLA and PHA. The results of a sensitivity analysis show that the GHG emissions become less than those of FBEPs when increasing the efficiency of separation and purification to more than 903\%, the PhLA yield to more than 20.6\%, the sugar extraction rate to 96\%, the Brix of sorghum juice to more than 19.4\%, and the sorghum yield to more than 79.2 t/ha. These results show that using the poly(PhLA) produced from sweet sorghum to replace the FBEPs has the potential to reduce fossil energy consumption and GHG emissions. (C) 2014 Elsevier Ltd. All rights reserved.
To enhance enzymatic saccharification of pine biomass, the pretreatment reagents peracetic acid (PAA) and ionic liquid (IL) were validated in single reagent pretreatments or combination pretreatments with different sequences. In a 1 h saccharification, 5-25\% cellulose conversion was obtained from the single pretreatment of PAA or IL In contrast, a marked enhancement in conversion rates was achieved by PAA-IL combination pretreatments (45-70\%). The PAA followed by IL (PAA + IL) pretreatment sequence was the most effective for preparing an enzymatic digestible regenerated biomass with 250-fold higher glucose formation rates than untreated biomass and 2- to 12-fold higher than single pretreatments with PAA or IL alone. Structural analysis confirmed that this pretreatment resulted in biomass with highly porous structural fibers associated with the reduction of lignin content and acetyl groups. Using the PAA + IL sequence, biomass loading in the pretreatment step can be increased from 5\% to 15\% without significant decrease in cellulose conversion. (C) 2013 Elsevier Ltd. All rights reserved.
Yarrowia lipolytica CGMCC 2.1506 was studied for tailored production of citric acid and mannitol by co-utilization of glucose and glycerol as carbon sources. Firstly, optimal cultivation conditions for producing the two products were determined using synthetic (SYN) media. The determined conditions were further applied and verified by Y. lipolytica cultivated with corn stover enzymatic hydrolysate (CSH) media derived from glycerol-assisted instant catapult steam explosion (ICSE) without detoxification, glycerol removal or nutrient addition. A high citric acid concentration of 63.8 +/- 2.6 g/L was achieved from CSH media containing 50.0 +/- 0.8 g/L glucose and 46.3 +/- 2.3 g/L glycerol, in a 5 L bioreactor at pH 5.5. In contrast, a high mannitol concentration of 37.1 +/- 1.5 g/L was obtained from a similar hydrolysate at pH 3.5. This study demonstrated that the integrated process based on glycerol-assisted ICSE pretreatment and tailored production of two important building block chemicals by Y. lipolytica is promising for biorefining of lignocellulosic biomass.
The exploration of sustainable lignocellulosic nanomaterials with unique properties and applicable functions is receiving growing interest. In this work, holocellulose nanofibrils (HCNFs) were prepared from moso bamboo using mild alkaline peroxide bleaching method (MAPB) followed by mechanical nanofibrillation. MAPB was proved to effectively remove lignin and retain hemicellulose. Meanwhile, partial allomorphic changes from cellulose I to cellulose II were revealed together with varying degrees of crystallinity. Thermogravimetric analysis (TGA) experiment showed an increasing thermal stability trend due to more allomorphic changes into anti-parallel cellulose II. Well-dispersed HCNFs suspensions were successfully prepared by homogenization and HCNFs films with high transparency and flexibility were fabricated. The films reached the maximum tensile strength of 55.8 MPa and tensile strain of 1.55 \% along with a calculated toughness of 25 MJ/m3. Moreover, the prepared materials are biocompatible and completely non-toxic, which will theoretically support the application of HCNFs materials in fields of biology, medicine and food industry.
Clay replacement with waste rice husk ash (RHA) and ceramic sludge (CS), helps to reduce the consumption of natural clay and solves the ecological issues created by waste disposal. In this study, properties of waste RHA and CS added fired clay tile were investigated, focusing on structural, durability, thermal performance as well as the water quality of the harvested run-off from fired clay roof tiles manufactured in an industrial scale plant. Tiles were cast by clay replacement with waste RHA and CS in four mixtures: 10 \%RHA and 0 \% CS, 10 \% RHA and 10 \% CS, 10 \% RHA and 15 \% CS, and 10 \% RHA and 20 \% CS (by weight). For 10 \%RHA and 10 \%CS tiles, dry mass was reduced by 4.9 \%, compared with conventional roof tiles, promising a light weight roof tile. Roof tiles with 10 \% RHA and 10 \%CS showed a transverse breaking load of 1519 N, whereas that of 20 \%CS tiles showed 1427 N, indicating that a further 6.5 \% strength improvement can be achieved with clay replacement with a combination of two waste materials. Clay replacement with 10 \% RHA and 10 \% CS resulted in water absorption of 15.25 \%. When increasing the clay replacement with combined waste from 10\% (10 \%RHA and 0\%CS) to 30 \% (10\%RHA and 20 \%CS), weight gain due to acid and alkaline attacks reduced from 3.5\% to 3.0\%, and from 2.2 \% to 1.6 \%, respectively, indicating enhanced durability performance by incorpo-rating combined waste. High porosity, also confirmed by SEM, contributed to enhanced thermal performance: tile with 10 \% RHA and 10 \% CS achieved 4.4 C temperature reduction, compared to the conventional tile. pH value and total solid concentration of run-off water were in the range of recommended values of water for agricultural purposes, ensuring that the collected run-off can be utilized as an alternative water source for potable activities.
Pretreatment to enhance the enzymatic digestibility of cellulose usually alters the structure of lignin, resulting in subsequent inferior depolymerization and utilization. Herein, a physicochemical pretreatment strategy, specifically, using a recyclable acid hydrotrope (p-toluenesulfonic acid,p-TsOH) followed by 10 s of ultrasonic treatment, was developed to facilitate high-value lignin extraction from lignocellulosic biomass and improve enzymatic hydrolysis for high-titer ethanol production. The wood material (poplar) was first treated with the recyclablep-TsOH aqueous solution under mild conditions (C80T80t15) to extract the lignin. The obtained lignin exhibited excellent properties, including a high hydroxyl (OH) content (4.19 and 4.07 mmol/g of aliphatic and phenolic OH, respectively), abundant beta-O-4 aryl ether linkages (60\%), a low M-w (3357 +/- 121 g/mol), and a narrow polydispersity (2.28, M-w/M-n), according to the results from FTIR spectroscopy, TGA,P-31 NMR spectroscopy, 2D-HSQC NMR spectroscopy, and GPC. The pretreated substrates were then subjected to 10 s of ultrasonication to improve the enzymatic saccharification and finally afford ethanol by quasi-simultaneous enzymatic saccharification and fermentation (Q-SSF). The highest ethanol concentration (40.08 +/- 3 g/L) was obtained after 60 h of fermentation, and the residual glucose concentration was only 4.22 +/- 1 g/L; this experimental ethanol yield was equivalent to the theoretical ethanol yield of 81.87 +/- 4\% based on the glucan content. In short, this pretreatment method simultaneously enhanced the accessibility of cellulose to enzymatic hydrolysis and provided high-value lignin. {[
Glycerol organosolv pretreatment (GOP) is considered an efficient method to deconstruct lignocellulose for producing fermentable sugars. Herein, the liquid fraction containing glycerol after GOP was utilized for recycled pretreatment of corn stover (CS) for four cycles. Enzymatic yield of glucose after recycled pretreatment was enhanced by 2.4-3.5 folds compared with untreated CS. Meanwhile, residual glycerol was used as carbon source for cultivation of Pichia pastoris to obtain high cell-density, and a final titer of 1.3 g/L human lysozyme was produced by P. pastoris under low temperature methanol induction strategy. Additionally, the pretreated CS was mixed with cassava as fermentable substrates for butanol production by wild-type Clostridium acetobutylicum ATCC 824. Final butanol production of 13.9 g/L was obtained from mixed substrates (25\%:75\% of CS/cassava) at 10\% solids loading by simultaneous saccharification and fermentation. Overall, integration of residual glycerol utilization and butanol production by microbial fermentation provided an efficient strategy for biorefinery.
The effects of microwave assisted liquid hot water (MA-LHW) pretreatment on the chemical composition of Moso bamboo were investigated, and the fiber structure of pretreated residues were studied. The results showed that MA-LHW pretreatment had high selectivity for the degradation of hemicellulose in Moso bamboo, and the extracted hemicellulose could be used to prepare xylooligosaccharide through enzyme depolymerization. The degradation rates of cellulose and lignin after MA-LHW pretreatment were only 14.73\% and 7.18\%, which were significantly lower than those of LHW pretreatment; 155.0 mg/g xylobiose and 61.0 mg/g xylotrisoe can be obtained after enzymatic hydrolysis, and the yield of xylo-oligosaccharide reached 80.59\% of the theoretical conversion rate. MA-LHW pretreatment increased the removal of hemicellulose, lignin, and other non-crystalline parts in bamboo materials, and more cellulose with crystalline structure was retained, which increased the CrI value of Moso bamboo by 14.84\%. FTIR spectra showed that the characteristic peak intensity of hemicellulose was significantly reduced after MA-LHW pretreatment, which confirmed the selective degradation of hemicellulose by MA-LAW pretreatment. Moreover, MA-LHW pretreatment also destroyed O-H, C-H, C-O-C, and beta-glucoside bonds in Moso bamboo fiber, caused by the recombination and synthesis of some groups (-CH2 and C=O) of cellulose, hemicellulose, and lignin destroyed under pretreatment conditions.
The use of lignocellulosic raw materials in bioethanol production has been intensively investigated in recent years. However, for efficient conversion to ethanol, many pretreatment steps are required prior to hydrolysis and fermentation. Coffee stands out as the most important agricultural product in Brazil and wastes such as pulp and coffee husk are generated during the wet and dry processing to obtain green grains, respectively. This work focused on the optimization of alkaline pretreatment of coffee pulp with the aim of making its use in the alcoholic fermentation. A central composite rotatable design was used with three independent variables: sodium hydroxide and calcium hydroxide concentrations and alkaline pretreatment time, totaling 17 experiments. After alkaline pretreatment the concentration of cellulose, hemicellulose, and lignin remaining in the material, the subsequent hydrolysis of the cellulose component and its fermentation of substrate were evaluated. The results indicated that pretreatment using 4\% (w/v) sodium hydroxide solution, with no calcium hydroxide, and 25 min treatment time gave the best results (69.18\% cellulose remaining, 44.15\% hemicelluloses remaining, 25.19\% lignin remaining, 38.13 g/L of reducing sugars, and 27.02 g/L of glucose) and produced 13.66 g/L of ethanol with a yield of 0.4 g ethanol/g glucose. (c) 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:451-462, 2014
Silica nanoparticles (SiNPs), have recently emerged as important nanomaterials with immense applications in various fields. Owing to their variable pore size, high surface area, surface reactivity, structural flexibility, stability, and low toxicity SiNPs are appealing to be employed in numerous fields including biomedicine and environment remediation. Though several methods are being applied for the synthesis of SiNPs from various sources; the key inclination in this regard is the concept of environment safety and ``green{''
Major progress in the bioprocessing of lignocellulose to fuels and value-added chemicals has created the possibility of a low carbon-footprint economy. However, the current complexity and associated costs of lignocellulose conversion result in a higher price for ethanol than for fossil fuels. The cost of cellulosic ethanol production will be lowered by further progress in development of biorefinery technology that produces both ethanol and high-value chemicals with bio-based products that are beginning to penetrate consumer markets in the USA, Brazil, and worldwide. The cost-effectiveness of low carbon-footprint bioproducts will benefit from advances in supplying large amounts of biomass solids to the biorefinery. We describe here outcomes from a successful long-term international cooperation between the Laboratory of Renewable Resources Engineering (LORRE) at Purdue University in the United States and Brazil's Agricultural Research Corporation (EMBRAPA) and Federal University of Sao Carlos (UFSCar), which has contributed practical pathways to enhance the biorefinery concept. This paper gives an overview of developments that address fundamental knowledge of lignocellulosic biomass pretreatment hydrolysis under optimized operational conditions and bioreactor configurations, and the science and engineering that contributes to the effective production of fuel and ethanol and value-added products from biomass. (c) 2020 Society of Chemical Industry and John Wiley \& Sons, Ltd
In this present investigation, functional (conducting) carbon were synthesized by direct pyrolysis method followed by carbonization process from the dead plant leaves of Solanum lycopersicum (SLL)without any external activation and applied for the energy storage system of supercapacitors. This technique is very simple and applicable to most of the dried forms of biomass. The synthesized functional carbon were characterized by X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy (RAMAN), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), Field Emission Scanning Microscopy (FESEM) and Transmission electron microscope (TEM) techniques. The synthesized functional carbon electrode materials of SLL were also tested by cyclic voltammetry (CV), galvanostatic charge and discharge (CD), Impedance analysis in aqueous electrolyte (1 M H2SO4) and cycle stability test. By using three-electrode systems, the electrode material of SLL-1000 shows best capacitance performance of 345 F/g when compared to other samples of dried SLL -600 and 800. The dried leaves of SLL-1000 based supercapacitor exhibits high 43.13 Wh/kg (energy density) at 61.34 W/kg (power density) in 1 M H2SO4. From the results, it highlights the success of preparing high capacitance electrode materials from functional carbon which are micro or mesoporous synthesized from SLL as a raw material for supercapacitors application.
Pyrolysis of pine needles was carried out in a semi-batch reactor. The effects of pyrolysis parameters such as temperature (350-650 A degrees C), heating rate (10 and 50 A degrees C min(-1)), nitrogen flow rate (50-200 cm(3) min(-1)) and biomass particle size (0.25-1.7 mm) were examined on products yield. Maximum bio-oil yield of 43.76\% was obtained at pyrolysis temperature of 550 A degrees C with a heating rate of 50 A degrees C min(-1), nitrogen flow rate of 100 cm(3) min(-1) for biomass particle size of 0.6 < d (p) < 1 mm. The characterization of pyrolysis products (bio-oil, bio-char) has been made through different instrumental methods like Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy (H-1 NMR), X-ray powder diffraction, field emission scanning electron microscope and Brunauer-Emmett-Teller surface area analysis. The empirical formula of the bio-oil and bio-char was found as CH1.47O0.36N0.005 and CH0.56O0.28N0.013 with heating value of 26.25 and 25.50 MJ kg(-1), respectively. Results show that bio-oil can be potentially valuable as a renewable fuel after upgrading and can be used as a feedstock for valuable chemicals production. The properties of bio-char reveal that it can be used as solid fuels, as a cheap adsorbent and as a feedstock for activated carbon production.
The dilute acid hydrolysis using corn stover (CS) to produce reducible sugars was optimized by the response surface methodology. The electron-equivalent balances of the main metabolites during the dark fermentation (DF) using acid hydrolysate were investigated to identify the evolutions of the electron sinks over the course of DF. The additions of nickel ion and Ni-0 nanoparticles (NPs) were found to effectively enhance the hydrogen production at experimental conditions. The optimal condition (HCl 2.5 wt\%, hydrolyzing duration 105 minutes, pH=5, S/B=3.5, Ni-0 NPs=10 mg/L-1) was achieved with Y-H2/S reaching 1.18 (mol.mol(-1)-glucose). The Y-H2/S increased from 0.7 (mol.mol(-1)-glucose) to 1.18 (mol.mol(-1)-glucose) reaching 40\% hydrogen yield increase when Ni-0 NPs was added to the fermentation broth. Among the investigated significant soluble metabolites, the butyric acid was found to serve as the largest e-sink in the electron-equivalent balance. The additions of Ni-0 NPs at low level (below 10 mg/L) were found to appreciably increase the hydrogen production. The increased pH and substrate to biomass ratio were found to skew the metabolic balance from hydrogen production to the biosynthesis (an increase of biomass). The proposed anaerobic digestion model with consideration of the inhibitory factors model presents a good agreement with the experimental data. The chemical addition such as nickel ions, Ni-0 NPs was found to be a practical approach in enhancing biohydrogen production using CS acid hydrolysate as cultivation broth.
In recent years, lignocellulosic biomass has emerged as one of the most versatile energy sources among the research community for the production of biofuels and value-added chemicals. However, biomass pretreatment plays an important role in reducing the recalcitrant properties of lignocellulose, leading to superior quality of target products in bioenergy production. Among existing pretreatment techniques, liquid hot water (LHW) pretreatment has several outstanding advantages compared to others including minimum formation of monomeric sugars, significant removal of hemicellulose, and positive environmental impacts; however, several constraints of LHW pretreatment should be clarified. This contribution aims to provide a comprehensive analysis of reaction mechanism, reactor characteristics, influencing factors, techno-economic aspects, challenges, and prospects for LHW-based biomass pretreatment. Generally, LHW pretreatment could be widely employed in bioenergy processing from biomass, but circular economy-based advanced pretreatment techniques should be further studied in the future to achieve maximum efficiency, and minimum cost and drawbacks.
The present work aimed to investigate the pretreatment of oil palm mesocarp fiber (OPMF) in subcritical H2O-CO2 at a temperature range from 150-200 degrees C and 20-180 min with CO2 pressure from 3-5 MPa. The pretreated solids and liquids from this process were separated by filtration and characterized. Xylooligosaccharides (XOs), sugar monomers, acids, furans and phenols in the pretreated liquids were analyzed by using HPLC. XOs with a degree of polymerization X2-X4 comprising xylobiose, xylotriose, xylotetraose were analyzed by using HPAEC-PAD. Enzymatic hydrolysis was performed on cellulose-rich pretreated solids to observe xylose and glucose production. An optimal condition for XOs production was achieved at 180 degrees C, 60 min, 3 MPa and the highest XOs obtained was 81.60 mg/g which corresponded to 36.59\% of XOs yield from total xylan of OPMF. The highest xylose and glucose yields obtained from pretreated solids were 29.96\% and 84.65\%, respectively at cellulase loading of 10 FPU/g-substrate.
Delonix regia (common name: Flame tree) pods, an inexpensive lignocellulosic waste matrix, were successfully used to produce value-added bioethanol. Initially, the potentiality of D. regia pods as a lignocellulosic biomass was assessed by Fourier-transform infrared spectroscopy (FTIR), which revealed the presence of several functional groups belonging to cellulose, hemicellulose, and lignin, implying that D. regia pods could serve as an excellent lignocellulosic biomass. Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to optimize pretreatment conditions of incubation time (10-70 min), H2SO4 concentration (0.5-3\%), amount of substrate (0.02-0.22 g), and temperature (45-100 degrees C). Then, RSM-suggested 30 trials of pretreatment conditions experimented in the laboratory, and a trial using 0.16 g substrate, 3\% H2SO4, 70 min incubation at 90 degrees C, yielded the highest amount of glucose (0.296 mg center dot mL(-1)), and xylose (0.477 mg center dot mL(-1)). Subsequently, the same trial conditions were chosen in the downstream process, and pretreated D. regia pods were subjected to enzymatic hydrolysis with 5 mL of indigenously produced cellulase enzyme (74 filter per unit {[
In this study, a comparative analysis of different pretreatment strategies on hydrolysis and fermentation of brewers' spent grain for biobutanol production by C. beijerinckii is presented. Ozone (2.7\% w/w, 30 min, 40-60\% w/w humidity), sodium hydroxide (1-5 \% w/w NaOH, 30 min, 120 degrees C, 5-15 \% w/w BSG) and hydrogen peroxide (5\% w/w H2O2, pH 11.5, 60-180 min, 50 degrees C, 5-15 \% w/w BSG) were the pretreatments analyzed. Ozonolysis was not very effective for either the degradation of lignin or the recovery of fermentable sugars in the enzymatic process under the tested operation conditions. Maximum butanol and ABE concentrations, 5.3 +/- 0.2 g butanol/L and 6.8 +/- 0.2 g ABE/L, were observed when low moisture content was used (40\% w/w). The peroxide alkaline pretreatment was found to be the most effective for BSG, when it was conducted at 5\% BSG for 60 min. Under these conditions, sugar enzymatic yields of 62.8\% for glucose and 28.1\% for xylose and arabinose, referred to untreated BSG, and product concentrations of 11.0 +/- 0.2 g butanol/L and 13.7 +/- 0.2 g ABE/L, were achieved. The alkaline pretreatment at 15\% BSG with 1\% w/w NaOH also provided high butanol and ABE concentrations (7.3 +/- 0.1 g butanol/L and 8.9 +/- 0.1 g ABE/L). Both the sodium hydroxide alkaline and peroxide alkaline methods were highly successful as pretreatments of BSG for ABE production, with overall yields of 44.4 g butanol/kg BSG and 54.0 g ABE/kg BSG for NaOH pretreatment (15\% BSG, 1\% w/w NaOH) and 45.1 g butanol/kg BSG and 56.1 g ABE/kg BSG for H2O2 pretreatment (5\% BSG, 60 min).
The effect of microwave (MW)-assisted acid or alkali pretreatment (300 W, 7 min) followed by saccharification with a triple enzyme cocktail (Cellic, Optimash BG and Stargen) with or without detoxification mix on ethanol production from three cassava residues (stems, leaves and peels) by Saccharomyces cerevisiae was investigated. Significantly higher fermentable sugar yields (54.58, 47.39 and 64.06 g/L from stems, leaves and peels, respectively) were obtained after 120 h saccharification from MW-assisted alkali-pretreated systems supplemented (D+) with detoxification chemicals (Tween 20+ polyethylene glycol 4000 + sodium borohydride) compared to the non-supplemented (D0) or MW-assisted acid-pretreated systems. The percentage utilization of reducing sugars during fermentation (48 h) was also the highest (91.02, 87.16 and 89.71\%, respectively, for stems, leaves and peels) for the MW-assisted alkali-pretreated (D+) systems. HPLC sugar profile indicated that glucose was the predominant monosaccharide in the hydrolysates from this system. Highest ethanol yields (YE, g/g), fermentation efficiency (\%) and volumetric ethanol productivity (g/L/h) of 0.401, 78.49 and 0.449 (stems), 0.397, 77.71 and 0.341 (leaves) and 0.433, 84.65 and 0.518 (peels) were also obtained for this system. The highest ethanol yields (ml/kg dry biomass) of ca. 263, 200 and 303, respectively, for stems, leaves and peels from the MW-assisted alkali pretreatment (D+) indicated that this was the most effective pretreatment for cassava residues.
Effective lignocellulosic biomass saccharification is one of the crucial requirements of biofuel production via fermentation process. Organic acid pretreatments have been gained much interests as one of the high potential methods for promoting enzymatic saccharification of lignocellulosic materials due to their lower hazardous properties and lower production of inhibitory by-products of fermentation than typical chemical pretreatment methods. In this study, three organic acids, including acetic acid, oxalic acid, and citric acid, were examined for improvement of enzymatic saccharification and bioethanol production from oil palm trunk biomass. Based on response surface methodology, oxalic acid pretreated biomass released the maximum reducing sugar of 144 mg/g-pretreated biomass at the optimum condition, which was higher than untreated samples for 2.30 times. The released sugar yield of oil palm trunk also corresponded to the results of FT-IR analysis, which revealed the physical modification of cellulose and hemicellulose surface structures of pretreated biomass. Nevertheless, citric acid pretreatment is the most efficient pretreatment method to improve bioethanol fermentation of Saccharomyces cerevisiae TISTR 5606 at 1.94 times higher than untreated biomass. These results highlighted the selection of organic acid pretreatment as a potential method for biofuel production from oil palm trunk feedstocks.
Lignocellulosic biomass is the generally explored substrate to produce bioethanol for environ-mental sustainability due to its availability in abundance. However, the complex network of cellulose-hemicellulose-lignin present in it makes its hydrolysis as a challenging task. To boost the effectiveness of conversion, biomass is pre-treated before enzymatic hydrolysis to alter or destroy its original composition. Enzymes like Cellulases are widely used for breaking down cellulose into fermentable sugars. Enzymatic hydrolysis is a complex process involving many influencing factors such as pH, temperature, substrate concentration. This review presents major four pre-treatment methods used for hydrolysing different substrates under varied reaction conditions along with their mechanism and limitations. A relative comparison of data analysis for most widely studied 10 kinetic models is briefly explained in terms of substrates used to get the brief insight about hydrolysis rates. The summary of pre-treatment methods and hydrolysis rates including cellulase enzyme kinetics will be the value addition for upcoming researchers for optimising the hydrolysis process.
The industrial production of sugar syrups from lignocellulosic materials requires the conduction of the enzymatic hydrolysis step at high-solids loadings (i.e., with over 15\% solids {[
Ethanol-water (EW) process, an efficient and low energy consumption method for lignocellulose fractionation, has been applied to the valorization of Cynara cardunculus (cardoon) as an integrated biorefinery raw material. Cardoon is a perennial plant fully adapted to low fertility soils and could be a solution to improve the biomass supply in rural areas with marginal lands. The purpose of this study is to optimize the fractionation of cardoon biomass, maximizing glucose yield in the subsequent enzymatic saccharification. Operational conditions have been optimized using Taguchi statistical approach, being the responses: recovery of glucans, hydrolysis yield of xylans, delignification yield and enzymatic hydrolysis rate. The variables studied have been: time, temperature, liquid/solid (L/S) ratio and ethanol concentration; each variable was studied at three levels. The best treatment conditions are achieved at the maximum tested values for time, temperature and L/S ratio (120 min, 190 degrees C and 30 L/kg, respectively), and the intermediate level for the ethanol concentration (33\%). Nevertheless, temperature is the most influential variable and, with a moderate energy input (60 min, 190 degrees C, 20 L/kg and 25\% of ethanol), cardoon retains most of the glucans (> 97\%), while significant amounts of xylans (> 68\%) and lignin (> 58\%) are removed, resulting in a a high glucose yield (c.a. 72\%) in the subsequent enzymatic saccharification process. Therefore, EW treatment leads to similar glucose yields if compared to other pre-treatments, but at a fraction of the energy input.
Two-stage anaerobic digestion (TAD) of tofu processing residue (TPR) was investigated, considering the impacts of operational conditions on microbial community diversity and biohythane production. The results showed that the optimal conditions of TAD were dark fermentation (DF) operated at a substrate-to-inoculum ratio (SIR) of 8, 5\% solid content, and 37 degrees C for 36 h, followed by methanogenic fermentation (MF) performed at a SIR of 1 and 37 degrees C for 13 days, which produced 324.4 mUg-VSfed of biohythane along with 103 mM acetic acid and 38 mM propionic acid. Compared to one-stage anaerobic digestion, TAD improved specific energy recovery by 45.3\%, producing a biogas yield of 189.6 mL/g-VSfed. SIR and temperature affected microbial community diversity of DF system, where high-SIR speciated hydrogen producers such as Mobilitalea and Clostridium sensu stricto/at thermophilic and mesophilic temperatures, respectively, whereas low-SIR stimulated methane generation by the speciation of Methanoculleus thermophilus. Likewise, hydrogenotrophic methanogens (Methanomassiliicoccus) enriched MF reactors operated at low-SIR. Overall, this study demonstrated TAD as an efficient technology for producing clean energy and value-added products using TPR.
Bioethanol production from lignocellulosic residues is an alternative to ensure energy supply required in the coming years and to achieve both environmental and economic benefits; however carbohydrates in lignocellulosic residues are found within a strong reticular network; therefore a pretreatment of the residues is necessary to modify the structure and to have access to carbohydrates and to obtain high yields in bioethanol production. This review discusses the different pretreatments of lignocellulosic residues that can be classified as physical, physicochemical, chemical and biological, with the principal objective to modify the structure of lignin and to permit the release of carbohydrates. Technological development in this topic is recent and the optimization of pretreatments for the production of bioethanol from lignocelullosic residues is needed to be feasible at industrial scale, which is the main objective to reach.
Fossil depletion is facing critical crisis due to its depletion reserves and increased environmental problems. The utilization of petroleum products by the dense population, urbanization of various geographical areas and industrialization has extremely affected the global economy. Fuels of biological origin such as ethanol, vegetable oil and various biomasses are gaining attention It is therefore important to develop alternative fuels in order to protect the global environment and also to focus on long-term supplies of conventional fuels. These biofuels have greater opportunity to promote agro-industrial development and productivity in large scale. Thus, it is necessary to improvise technology and develop resource sustainability focussing into the appropriate policies, production costing, yield, purity and efficiency creating health, wealth and benefit sharing to achieve a sustainable energy in future. The present review article focuses on the recent trends and researches carried out in liquid biofuel production and economy holding its future demand and utilization world-wide.
Ionic liquids (ILs) have been increasingly exploited as solvents and/or reagents in many applications due to their ``green{''
Due to environmental issues and the depletion of fossil-based resources, ecofriendly sustainable biomass-based chemical production has been given more attention recently. Succinic acid (SA) is one of the top value added bio-based chemicals. It can be synthesized through microbial fermentation using various waste steam bioresources. Production of chemicals from waste streams has dual function as it alleviates environmental concerns; they could have caused because of their improper disposal and transform them into valuable products. To date, Actinobacillus succinogenes is termed as the best natural SA producer. However, few reviews regarding SA production by A. succinogenes were reported. Herewith, pathways and metabolic engineering strategies, biomass pretreatment and utilization, and process optimization related with SA fermentation by A. succinogenes were discussed in detail. In general, this review covered vital information including merits, achievements, progresses, challenges, and future perspectives in SA production using A. succinogenes. Therefore, it is believed that this review will provide platform to understand the potential of the strain and tackle existing hurdles so as to develop superior strain for industrial applications. It will also be used as a baseline for identification, isolation, and improvement of other SA-producing microbes.
Hydrogen production through biological route is the cleanest, renewable and potential way to sustainable energy generation. Productions of hydrogen via dark and photo fermentations are considered to be more sustainable and economical approach over numerous existing biological modes. Nevertheless, both the biological modes suffer from certain limitations like low yield and production rate, and because of these practical implementations are still far away. Therefore, the present review provides an assessment and feasibility of integrated biohydrogen production strategy by combining dark and photo-fermentation as an advanced biochemical processing while using lignocellulosics biomass to improve and accelerate the biohydrogen production technology in a sustainable manner. This review also evaluates practical viability of the integrated approach for biohydrogen production along with the analysis of the key factors which significantly influence to elevate this technology on commercial ground with the implementation of various environment friendly and innovative approaches.
The aim of this study was to investigate a pretreatment by combined H2SO4 acid-catalyst and thermomechanical process to improve hemicelluloses solubilization of hemp hurds and subsequently enzymatic hydrolysis extent of potentially fermentable sugars. It was found that the sugars released were gradually increased with treatment severity. Soluble sugars generated before enzymatic hydrolysis (R-1) increased up to 2.23 g/L indicating that autohydrolysis reaction occurred during pretreatment. Consequently, the solubilization of hemicelluloses was correlated with combined severity factor (CS). As a result, increase of overall reducing sugars (ORS) from 23.4\% (untreated) to 81.4\% was observed at optimized conditions of steaming temperature of 165 degrees C for 30 min and acid loading of 62.9 g/kg DM (dry material) corresponding to CS = 1.2, with limited production of identified by-products: 0.035 g/L and 0.46 g/L (per 100 g DM) for furfural and HMF, respectively. Structural and physicochemical modifications of biomass were observed by FTIR, ABET and SEM.
In this study, anaerobic digestion (AD) of hazelnut (Corylus colurna) husks (HH) was investigated by NaOH pretreatment at 1-6\% w/w concentrations. The highest methane yield was 278.45 +/- 7.85 mL/g volatile solid (VS), and this was obtained in a 4\% NaOH pretreated reactor. In this reactor, the methane yield increased by 162.2\% compared to that in the control. The concentrations of volatile fatty acids (VFAs) varied during the digestion process according to the different NaOH pretreatment results. The highest lignosellulosic solubilizations were obtained in a 6\% NaOH pretreated reactor. Furthermore, in the second part of kinetic studies, it was defined critical points for cumulative methane yield (CMY) in the Logistic model (LM). These points were the absolute acceleration point (PAA), maximum acceleration point (PAM), inflection point (PI), maximum deceleration point (PDM), and asymptotic deceleration point (PDA). Using these points on the CMY curves, the AD process of HH was mathematically interpreted and explained.
The homogeneous chemical modification of cellulose with succinic anhydride was investigated in a solvent system containing 1-butyl-3-methylimidazolium chloride ionic liquid and dimethylsulfoxide using N-bromosuccinimide (NBS) as a catalyst. The results showed that the degree of substitution of the succinylated cellulosic samples, in the range of 0.24-2.31, noticeably increased as compared with the products without any catalysts, indicating that NBS was a novel efficient catalyst for cellulose succinoylation in ionic liquids. Fourier transform infrared and solid-state cross-polarization/magic angle spinning C-13 NMR spectroscopies also provided evidence of succinoylation reaction. The results indicated that the reaction of hydroxyl groups at C-6, C-2, and C-3 positions in cellulose occurred. The thermal stability of the succinylated cellulose was found to decrease upon chemical modification.
The high degree of lignification in larch shows strong recalcitrance for its enzymatic digestibility to produce fermentation sugars for the further bio-energy production. Hence, pretreatment with excellent delignification ability should be carried out for larch. In this work, a high delignification degree of 77.3\% could be achieved for larch after kraft pretreatment, while it still had a low enzymatic digestibility (30.3\%), which was due to the remained stout cell wall structure revealed by confocal laser scanning microscopy. To elucidate the reason for low enzymatic digestibility, the addition of bovine serum albumin (BSA) and ball-milling were performed to investigate the substrate-related inhibiting factors of lignin and cellulose, respectively. It is found that the enzymatic digestibility of pretreated larch was enhanced to 58.8\% by the addition of BSA, which is due to the reduction of the non-productive binding between residual lignin and cellulases. In addition, ball-milled could disrupt the cellulose's crystalline structures, which enhance the enzymatic hydrolysis of BSA-absorbed larch to 77.7\%. This result indicated that cellulose structure is another inhibition bastion towards enzymatic digestion. This work revealed the effect of substrate-related factors that restrict the enzymatic digestibility of larch.
Surfactants were used for the hydrolysis of bamboo biomass to enhance lignocellulose hydrolysis. Tween 80, polyethylene glycol 4000 (PEG 4000), and sodium dodecyl sulfate (SDS) were tested as surfactants for improving the bamboo hydrolysis with a novel sulfonated cross-linked chitosan solid acid catalyst (SCCAC) in ionic liquid (IL). Compared to the use of only SCCAC in 1-Butyl-3-methylimidazolium chloride ({[
An attempt was made to investigate the synergistic effect and product characteristics in the microwave co-pyrolysis of lignite and corncob by using a self-designed microwave pyrolysis device. The results showed that the tar yield reached the maximum value of 16.31\%, an increase of 51.16\% to that of pure lignite pyrolysis and reached the most-positive deviation, with the addition of 30\% corncob. The formation of combustible gas in the gas product was increased with an increase of corncob. Compared with the pure lignite pyrolysis, the co-pyrolysis results showed the improvement in both qualities of tar and char, and reduced the initial lignite pyrolysis temperature, with the addition of corncob. The difference between the experimental and theoretical values of products yield, the surface area of char, and residue in the mixture all demonstrated the existence of synergistic effect during microwave co-pyrolysis. Kinetics analysis further confirmed that the synergistic effect was mainly reflected in enhancing the reactivity of co-pyrolysis.
Atmospheric low-temperature plasma has emerged as a promising pretreatment for lignocellulose to improve bio-refining. Herein, we investigated plasma-induced changes in the chemical structure of lignin to obtain a fundamental understanding of the plasma-lignocellulose interaction. Based on the results, plasma possesses a strong capacity to cleave C-C covalent bonds in the aliphatic region of lignin, accompanied by oxidation. Plasma treatment leads to the degradation and fragmentation of lignin. Pronounced deconstruction of beta-O-4 aryl ether is observed in plasma. The relative content of beta-O-4 aryl ether was reduced from the initial value of 65.1/100Ar to 58.7/100Ar for lignin from corncob and from the initial value of 72.5/100Ar to 63.8/100Ar for lignin from poplar after plasma treatment, respectively. According to the density functional theory analysis, the oxygen atom of beta-O-4 aryl ether is the most likely potential reaction site and the C-beta-O covalent bond exhibits the lowest decomposition free energy (50.5 kcal mol(-1)), which will easily be cleaved in plasma. The dominant reaction pathway of lignin degradation is the cleavage of the C-beta-O covalent bond followed by the cleavage of the C-beta-C-alpha bond. We propose that this investigation is beneficial to optimize and expand the applications of plasma treatment in pretreatment of lignocellulose.
This study extracted nanocellulose crystals from South African waste corncobs via liquid hot water pretreatment and alkali treatment. The pretreatment process was designed and optimized using Central Composite Design (CCD) and Response Surface Methodology (RSM), respectively setting temperature (150-200 degrees C), time (10-60 min), and solid loading rate (3-10\% w/w) as input variables. After pretreatment, the residue was treated with sodium hydroxide (2\%wt) at 90 degrees C for 90 min. The extracted nanocellulose crystal was filtered, washed with deionized water, and dried in an oven. The characterization of the nanocellulose crystal was carried out based on standard procedures. The positive correlations between the input variables were observed, whereby a rise in the pretreatment conditions improved the nanocellulose crystal yield. Hence, the study obtained an optimum yield of 55.5\% at 200 degrees C, 10\% w/w, and 60 min. The surface morphology showed a more porous and rougher surface, and the crystallinity analysis indicated that run 7 had the most crystalline nanocellulose crystal with a crystallinity index of 57.3\%. The study revealed that nanocellulose crystals could be extracted from corncobs via liquid hot water pretreatment and alkali treatment.
A new applicability of cell-immobilized system for biological production of target chemical was reported in this work. A. succinogenes CCTCC M2012036 was immobilized on positively charged polypropylene microfiber membrane by physical interaction and were used for converting glucose into succinic acid. Glucose consumption and succinic acid production kinetics were investigated for optimizing the operational parameters. The cell-immobilized membrane presented good reuse stability, and six cycles of fermentation without activity loss were realized with an average succinic acid yield of 0.83 g/g. Importantly, a biofilm was formed which favored the production of succinic acid. A microfiber membrane bioreactor was further constructed with the cell-immobilized membrane to perform fermentation in a larger scale, and the yield and productivity of succinic acid were 0.82 g/g and 1.04g L-1 h(-1) using a fed batch strategy. By combining mesoporous support with biotechnological techniques, this work offered a prospect of adopting reusable cells feasible for industry. (C) 2016 Elsevier Inc. All rights reserved.
The replacement of phenol with sodium lignosulfonate and formaldehyde with glutaraldehyde in the preparation of resins resulted in a new resol-type phenolic resin, sodium lignosulfonate-glutaraldehyde resin, in addition to sodium lignosulfonate-formaldehyde and phenol-formaldehyde resins. These resins were then used to prepare thermosets and composites reinforced with sisal fibers. Different techniques were used to characterize raw materials and/or thermosets and composites, including inverse gas chromatography, thermogravimetric analysis, and mechanical impact and flexural tests. The substitution of phenol by sodium lignosulfonate in the formulation of the composite matrices increased the impact strength of the respective composites from approximately 400 Jm(-1) to 800 J m(-1) and 1000 J m(-1), showing a considerable enhancement from the replacement of phenol with sodium lignosulfonate. The wettability of the sisal fibers increased when the resins were prepared from sodium lignosulfonate, generating composites in which the adhesion at the fiber-matrix interface was stronger and favored the transference of load from the matrix to the fiber during impact. Results suggested that the composites experienced a different mechanism of load transfer from the matrix to the fiber when a bending load was applied, compared to that experienced during impact. The thermogravimetric analysis results demonstrated that the thermal stability of the composites was not affected by the use of sodium lignosulfonate as a phenolic-type reagent during the preparation of the matrices.
Bioethanol recovery from food waste through high solids enzymatic hydrolysis (HSEH) and high solids bioethanol fermentation (HSBF) alleviate the energy crisis. However, this cause decreased glucose and bioethanol yields due to the high solids content. In this study, saponin was introduced into food waste HSEH and HSBF systems to enhance the product yields. Under the regulation of saponin, the substrate released >90\% of the theoretical reducing sugar. The glucose concentration increased by 137.41 g/L after 24 h of HSEH with 2.0\% saponin. The bioethanol titer reached 73.2 g/L (1.0\%-saponin). Untargeted metabolomics illustrating that saponin had higher antifungal properties at lower concentrations (0.5\%-saponin) that caused a decrease in bioethanol yield. The addition of saponin concentrations of 1.0\%similar to 3.0\% promoted HSEH, HSBF, and the metabolism of Saccharomyces cerevisiae; thus, 1.0\% was suggested for practical use. This study deepened the understanding of saponin in enhancing HSBF and provides theoretical support for further application.
Foamed plastics do not readily degrade, but degradable starch foam has uneven pores and poor mechanical properties. To improve the cushioning performance of starch foams, a sustainable starch-based packaging cushioning material is prepared through microwave foaming using waste corrugated paper fibers as the reinforcement material. The effects of different fiber contents on the structure and cushioning properties of starch-based foams are studied, and the possibility of replacing petroleum-based foams is discussed through comparisons with conventional cushioning materials. The results indicate that the pore structure of starch-based foaming materials can be controlled by changing the fiber dosage, and a small or excessive amount of fiber is not conducive to the uniform foaming of starch-based composite foams. When 3 g of wastepaper fiber (17.6\% by weight of starch) is added, the average diameter of the starch-based foam pores is small, the pore size distribution is relatively uniform, the minimum buffer coefficient is 4.38 and the mechanical properties are closer to those of expanded polystyrene. A peak acceleration of 942.89 m/s(2) is obtained from the packaging parts with starch-based foaming materials after drop testing, which reduces the impact load by nearly 50\% compared with that of packaging without a cushioning liner. This has the potential to become a sustainable alternative to petroleum-based packaging foams.
Burnt clay brick is one of the ancient building material. The use of waste materials in bricks can lessen the consumption of clay material and reduce the environmental burden due to accumulation of waste materials. Furthermore, addition of recycled materials can decrease the high carbon footprint. In the current study, bricks were manufactured using fly ash (by-product of coal) and conventional earthen materials. Fly ash was acquired from the coal power plant. Manufacturing of brick specimens was done in a local brick industry. The main variable in this study was the percentage of fly ash (i.e. 0-25\% of clay). Results indicate that the compressive strength of bricks incorporating fly ash was lower as compared to that of clay bricks without fly ash. However, compressive strength of bricks incorporating up to 20\% of fly ash satisfied the minimum requirements of the Pakistan Building Code. Reduction in weight was also observed in the fly ash bricks which would lead to overall weight reduction of the structures. Furthermore, less efflorescence was observed in bricks incorporating fly ash. Therefore, it can be concluded that clay bricks incorporating fly ash can be helpful in producing more sustainable bricks leading to economical solution.
Acetone soluble oil palm empty fruit bunch cellulose acetate (OPEFB-CA) of DS 2.52 has been successfully synthesized in a one-step heterogeneous acetylation of OPEFB cellulose without necessitating the hydrolysis stage. This has only been made possible by the mathematical modeling of the acetylation process by manipulating the variables of reaction time and acetic anhydride/cellulose ratio (RR). The obtained model was verified by experimental data with an error of less than 2.5\%. NMR analysis showed that the distribution of the acetyl moiety among the three OH groups of cellulose indicates a preference at the C6 position, followed by C3 and C2. XRD revealed that OPEFB-CA is highly amorphous with a degree of crystallinity estimated to be ca. 6.41\% as determined from DSC. The OPEFB-CA films exhibited good mechanical properties being their tensile strength and Young's modulus higher than those of the commercial CA. (C) 2015 Elsevier Ltd. All rights reserved.
Fast growing Kariba weed causes major problems and pollution on freshwater and shellfish aquaculture sys-tems by interfering with nutrient uptake of crops, restricting sunlight penetration, and decreasing water qual-ity due to massive biomass of Kariba weed remnants. Solvothermal liquefaction is considered an emerging thermochemical technique to convert waste into high yield of value-added products. Solvothermal liquefac-tion (STL) of Kariba weed as an emerging contaminant was performed to investigate the effects of different types of solvents (ethanol and methanol) and Kariba weed mass loadings (2.5-10 \% w/v) on treating and re-ducing the weed via conversion into potentially useful crude oil product and char. Up to 92.53 \% of Kariba weed has been reduced via this technique. The optimal conditions for crude oil production were found to be at 5 \% w/v of mass loading in methanol medium, resulting in a high heating value (HHV) of 34.66 MJ/kg and yield of 20.86 wt\%, whereas the biochar production was found to be optimum at 7.5 \% w/v of mass loading in methanol medium, resulting in 29.92 MJ/kg of HHV and 25.38 wt\% of yield. The crude oil consisted of beneficial chemical compounds for biofuel production such as hexadecanoic acid, methyl ester (65.02 peak area \%) and the biochar showed high carbon content (72.83 \%). In conclusion, STL as a remediation for emerg-ing Kariba weed is a feasible process for shellfish aquaculture waste treatment and biofuels production.
Brick is one of the common and vital construction materials which is used in all masonry works. A large land area is required for acquiring the voluminous quantity of the clay for brick manufacturing. An alternative material for clay, if burnt into brick, needs to be identified that can be added in brick as a replacement of clay in such a quantity that can effectively reduce the clay consumption as well as finely maintain the desirable qualities of the bricks. Therefore, this study evaluates the utilization of waste glass powder (WGP), as a potential alternative for partially replacing clay, in the manufacturing process of fired clay bricks by carrying out various engineering tests such as compressive strength, water absorption, dimension tolerance, colour variation, hardness, soundness, efflorescence, structure, and resistance against the impact on the clay only bricks and the bricks incorporating the WGP with varying proportions. The study revealed that the optimum WGP content is 20\% by weight of the clay brick, which shows only 8.5\% water absorption and a 77\% rise in the compressive strength of the brick. Also, it is noted that a kiln temperature of 800 to 900 degrees C was required for baking the brick containing WGP, which is less than that required for the brick prepared by clay only. Economic analysis indicates that there can be an 11.3\% saving of manufacturing cost with the use of 20\% by weight of the WGP in the clay brick.
Waste materials are often used in brick manufacturing to develop a sustainable building material and reduce the consumption of natural clay resources. In this study, palm oil fuel ash (POFA), a waste generated from the palm oil industry, was used in brick production as clay replacement at dosages of 5, 10, 15 and 20\% by weight. The brick specimens were produced in a local factory to study the feasibility of manufacturing bricks containing POFA under real industrial production conditions and their properties were compared with conventional bricks (0\% POFA). The results show that a lighter brick is produced when mixed with POFA but the flexural and compressive strength decreased. Water absorption and initial rate of absorption increased when clay is mixed with POFA due to the presence of a more porous structure than conventional bricks. Further, brick specimens containing POFA had a higher resistance to the formation of efflorescence than conventional bricks; however, their resistance was poor when subjected to sulphate attack. The findings of this study suggest that up to 5\% POFA can be used as clay replacement for bricks produced in a local brick kiln industry to meet the current international standards for conventional bricks.
Combination of mortar grinder mill (MG) and ionic liquid (IL) treatment was employed in order to fibrillate fibers from oil palm mesocarp fiber (OPMF) in one-step. The structural changes of OPMF before and after the treatment were examined by Thermogravimetric analysis (TGA), Fourier transformed infrared (FT-IR) spectra, Wide-angle X-ray diffraction (WAXD), Dynamic light scattering (DLS) and Scanning electron microscopy (SEM). Compared with the only use of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM{[
Polyurethane foam (PUF) was used as a carrier for Candida tropicalis (C. tropicalis) in the multi-batches fermentation of xylitol from xylose-containing corncob hemicellulose hydrolysate. After washing and sterilization, PUF (density of 320 kg m(-3), specific surface area of 1.5-2.0 x 10(5) m(2) m(-3), average porosity of 95\%, pore diameter of 0.03 mm and cubic length of 5 mm) was mixed with the culture medium at appropriate proportion followed by the inoculation. The fermentation parameters such as initial cell concentration, PUF dosage, pH value and temperature were controlled to study the effects on xylitol fermentation. In the 21-day durability tests, the optimal xylitol yield and volumetric productivity reached to 71.2\% and 2.10 g L-1 h(-1) respectively. Moreover, the average xylitol yield and volumetric productivity were 66.3\% and 1.90 g L-1 h(-1) for ten batchwise operations. The current research demonstrated that the PUF immobilization could serve as an efficient method for improving the cells vitality and enzyme reactivity in the continuous operation of fermentation. (C) 2012 Elsevier Ltd. All rights reserved.
The kinetics of cotton cellulose hydrolysis using concentrated sulfuric acid and the performance of fermentative hydrogen production from the hydrolysate in the batch system was carried out in this study. Effects of sulfuric acid concentrations, cotton cellulose concentrations and operating temperatures on the cotton cellulose hydrolysis were investigated. It was found that cotton cellulose can dissolve completely in sulfuric acid concentration above 55\% (by volume) at room temperature. The reduced sugar yields were varied from 64.3 to 73.9\% (g R-sugar/g cotton cellulose) with the initial cotton cellulose concentrations of 30-70 g/L at a temperature of 40 degrees C. The reduced sugar concentrations and the initial pH of biohydrogen production were investigated at 37 degrees C. It was found that the optimal values of the hydrogen yield and substrate utilization were 0.95 mol H-2/mol R-sugar and 98\% with an initial pH of 8.2, when substrate concentration was fixed at 20 g R-sugar/L. The maximum hydrogen yield was 0.99 mol H-2/mol R-sugar at a substrate concentration of 15 g R-sugar/L. Using the Gompertz Equation Model simulation, the maximum hydrogen production rate was 253 mL H-2/h/L at a substrate of 30 g/L and initial pH of 8.4. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Sustainability is a major goal for the country development without negative effects on climate change, allied to scarcity and instability in the fossil fuels prices, makes attractive the use of several agricultural, forestry and industrial biomass which may undergo combustion processes for the production of renewable energy, either in its in natural form, pressed into dense pellets or briquettes, or after thermochemical conversion through gasification, pyrolysis, liquefaction, carbonization, and torrefaction. The aim of the current research was to identify the major environmental, economic and social impacts arising from the solid fossil fuels, as well as introduce a technical approach to address the scenario of the main energy crops produced in Brazil, wastes arising from the same, their quantification, and alternatives to using such wastes in the solid biofuels production. Moreover, it was intended to describe the current national and global market, policies, advantages, and challenges by using biofuels, in comparison with fossil fuels.
Bioethanol is one of the most promising and eco-friendly alternatives to fossil fuels, which is produced from renewable sources. Although almost all the current fuel ethanol is generated from edible sources (sugars and starch), lignocellulosic biomass (LCB) has drawn much attention in recent times. However, the conversion efficiency as well as ethanol yield of the biomass differs greatly with respect to the source and nature of LCB, primarily due to the variation in lignocellulosic content. Two major polysaccharides in LCB, namely, cellulose and hemicellulose firmly link to lignin and form a complex lignocellulosic network, which is highly robust and recalcitrant to depolymerization. For this reason, generation of ethanol from LCB requires a complicated conversion process that has made it commercially non-competitive. As attempts to exploit LCBs into commercial ethanol production, recent research efforts have been devoted to the techno-economic improvements of the overall conversion process, in addition to screen out promising feedstocks. This review paper presents an overview on the diversity of biomass, technological approaches and microbial contribution to the conversion of LCB into ethanol. (C) 2016 Elsevier Ltd. All rights reserved.
Among the diversity of solid waste produced, biomass by-products stand out due to their synergizing role in energy savings during brick firing process and impact on mitigating sustainability issues of fired clay brick production. Therefore, this study accentuates on assessing the characteristics of fired clay bricks made by replacing clay with both biomass bottom ashes (BBA) and spent charcoal from 8 to 20 wt\% in order to minimize non-renewable resource use and enhance brick performance. In total, bricks from 6 mixture series were prepared to ascertain the effect of 5 wt\% BBA incorporation and 3 - 15 wt\% spent charcoal addition on the physical, durability, mechanical and thermal properties of the produced fired clay bricks. Parameters such as linear shrinkage, dried weight, dried and fired apparent densities, water absorption, open porosity, thermal conductivity and compressive strengths were examined at spent charcoal increasing inclusion in the brick bodies. The produced bricks showed linear shrinkage values within the safe limits of 7\%. Water absorption values were also within acceptable levels of 16.33\%. Thermal conductivity significantly reduced from 0.76 W/mK to 0.58 W/mK and this reduction meant improvement in the thermal efficiencies of the bricks. Bricks containing 5 wt\% BBA and 9 wt\% of spent charcoal exhibited compressive strengths of 10.40 MPa in accordance with standards required for structural construction. These results were authenticated from mineralogical and microstructural analyses. Consequently, utilization of up to 20\% wastes in a brick body is a crucial step in point of economic growth, environmental cleanliness, natural clay resources conservation and innovation in the fired clay bricks product development.
The aim of the present study is obtaining the calorific values and the qualitative properties of the pellets made from four agricultural by-products co-fired with coal and non-cofired, in order to highlight the importance of co-fired biomass as alternative energy source. The studied samples are coarse ground grist of sorghum seeds, rape seeds, soyabean, sunflower seeds and their mixture with coal. The following parameters are calculated: higher heating values, bulk densities, energy densities, fuel value index, nitrogen, and sulphur content. The proximate composition as defined by ASTM was established: moisture, ash, volatile matter, and fixed carbon. The moisture and ash content of the studied agricultural by-products are identified as the main factors of calorific influence. The obtained results come to confirm the ability of co-fired biomass to be used as fuel. As resulted from the experimental data, the co- fired biomass of agricultural residues are good resources as biofuel in the form of pellets. Among the studied samples, co-fired sunflower seeds grist presents the highest heating value, highest fixed carbon content and fuel value index, thus being a good alternative to fossil fuel in order to produce energy and reduce the domestic air pollution and the amount of wood needed.
The major challenge for natural fiber composites is their inherent poor adhesion between fiber and the matrix, high moisture absorption, and UV degradation. Lignin and hemicelluloses are the major composites of natural fiber which are responsible for UV degradation and moisture absorption, respectively. In this study, the lignocelluloses (oil palm empty fruit bunch) were treated with alkaline peroxide to separate lignin and hemicelluloses. Composites were produced with treated and untreated fibers using up to 45\% fiber with polypropylene matrix using twin-screw extruder followed by injection molding. To improve the interfacial bonding, maleic anhydride grafted polypropylene (MAPP) was used as a coupling agent in the formulation. Properties of composites were evaluated using tensile testing, flexural testing, impact testing, SEM, and FTIR. The tensile, flexural, and impact properties were found to be improved with alkaline peroxide-treated fiber composites compared to untreated fiber composites. Addition of coupling agent (MAPP) also found to provide improved properties of composites.
Semi-interpenetrating polymer network (semi-IPN) of poly(vinyl alcohol)/polyacrylamide was reinforced with various doses of nanocellulose. The different composite films thus prepared were characterized with respect to their mechanical, thermal, morphological and barrier properties. The composite film containing 5 wt.\% of nanocellulose showed the highest tensile strength. The semi-interpenetrating polymer network of poly(vinyl alcohol)/polyacrylamide; and its various composites with nanocellulose were almost identical in their thermal stability. Each of the composites however exhibited much superior stability with respect to the linear poly(vinyl alcohol) and crosslinked polyacrylamide. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies exhibited phase separated morphology where agglomerates of nanocellulose were found to be dispersed in the matrix of the semi-IPN. The moisture vapor transmission rate (MVTR) was the lowest for the film containing 5 wt.\% of nanocellulose. (C) 2015 Elsevier Ltd. All rights reserved.
India generates approximately 500 million tons of agricultural crop residues per year. This crop residue (waste) can be converted into fuel by using thermo-chemical and bio-chemical conversion routes. Thermo-chemical conversion routes mainly include gasification, pyrolysis, and liquefaction. In recent years, the pyrolysis technology for the production of bio-oil is gaining attention globally, due to its simple and efficient conversion techniques. This paper provides the updated review of bio-oil production mainly from agricultural crop residues and focuses on the different bio-oil production techniques such as fast pyrolysis and hydrothermal liquefaction; the reactor used for bio-oil production, properties, and application of bio-oil. The bio-oil produced from agricultural residues has a heating value of between 17-21 MJ/kg, exactly half of the diesel fuel. The properties of bio-oil showed the potential ability to be used as fuel in many applications such as boiler, furnaces, and diesel engines.
This Review focuses on the use of ultrasound to produce chemicals from lignocellulosic biomass. However, the question about the potential of sonochemistry for valorization/conversion of lignocellulosic biomass into added-value chemicals is rather conceptual. Until now, this technology has been mainly used for the production of low-value chemicals such as biodiesel or as simple method for pretreatment or extraction. According to preliminary studies reported in literature, access to added-value chemicals can be easily and sometimes solely obtained by the use of ultrasound. The design of sonochemical parameters offers many opportunities to develop new eco-friendly and efficient processes. The goal of this Review is to understand why the use of ultrasound is focused rather on pretreatment or extraction of lignocellulosic biomass rather than on the production of chemicals and to understand, through the reported examples, which directions need to be followed to favor strategies based on ultrasound-assisted production of chemicals from lignocellulosic biomass. We believe that ultrasound-assisted processes represent an innovative approach and will create a growing interest in academia but also in the industry in the near future. Based on the examples reported in the literature, we critically discuss how sonochemistry could offer new strategies and give rise to new results in lignocellulosic biomass valorization.
In recent year, the interest in environmentally friendly materials, like cellulose nanostructures (CNSs) has increased. Nanoscale dimensions, high surface area, low density, and high mechanical strength are examples of CNSs properties that attract researchers' attention. CNSs stability and dispersity are the main limitations that prevent its application as nanofiller in polymeric matrices. In this work, the surface modification of CNSs was investigated. To overcome CNSs limitation, they were modified with polyethylene glycol (PEG), in aqueous solution, in different proportions: 2, 5 and 10 wt\%. FFIR, elemental analysis, NMR, and XPS were carried out to verify the adsorption efficiency. The results showed an excellent adsorption of PEG chains on the CNSs surface, with particle size increase of 50-90 nm and a considerable increase in thermal stability. XRD and AFM analysis observed no significant variation in crystallinity and morphology in modified CNSs. Thus, modification of CNSs with PEG is an environmentally friendly process and showed positive results regarding improving CNSs stability, in aqueous media. (C) 2018 Published by Elsevier B.V.
The need for fossil fuel alternatives keeps increasing. Bioethanol and biohydrogen have emerged as significant renewable options. However, these bioprocess routes have presented various challenges, which constantly impede commercialization. Most of these bottlenecks are hinged on feedstock logistics, low biofuel yield and enormous process costs. Meanwhile, a large output of renewable energy can be generated from mixed starch-based agricultural wastes due to their intrinsic bioenergy characteristics. This study, therefore, focuses on the production of bioethanol and biohydrogen from mixed starch-based agricultural wastes. The content further highlights the current challenges of their individual processes and elucidates the prospects for improvement, through an integrated biofuel approach. The use of mixed starch-based agricultural wastes as substrates for integrated bioethanol and biohydrogen production was proposed. Furthermore, the use of mixture-based experimental design for the determination of optimal values of critical factors influencing biofuel production emerges as a viable prospect for profitable bioethanol production from the starch-based biomass. Additionally, biohydrogen production from effluents of the mixed starch-based waste bioethanol looked promising. Thus, the study proposed valuable insights towards achieving a cost-effective biofuel technology.
In this study, NaOH pretreatment, H2SO4 pretreatment, thermal pretreatment and production temperature were optimized to ensure maximum methane yield from hazelnut shells (HS) using the response surface methodology (RSM). A Box-Behnken design was achieved with four different independent variables and one dependent variable (methane yield). A total of 29 tests were performed after pretreatment according to the RSM design and to different production temperatures, suggesting optimum values for NaOH pretreatment, H2SO4 pretreatment, thermal pretreatment and production temperature were 3.5\% w/v, 2.56\% v/v, 145.66 degrees C and 34.65 degrees C, respectively. Under these conditions, the RSM-predicted methane yield was 215.896 mL/g volatile solid (VS). The high R-2 value (0.9904) showed that the model could be applied effectively in the digestion of HS for the predicted methane yield according to the production temperature and pretreatments. In addition, lignocellulosic solubilisation was tested after pretreatment of the reactors according to the RSM operating conditions, which showed that the highest cellulose, hemicellulose and lignin solubilisation that could be achieved was 38.7\% w/w (R-10), 36.9\% w/w (R-22) and 50.5\% w/w (R-10), respectively. The modified Gompertz model supported the experimental cumulative methane yields (CMYs).
The agricultural sector is a major source of biomass feedstocks for biofuels. Even though biomass potential in Thailand has been analyzed on a national level, its distribution and potential have yet to be assessed on a regional and provincial scale. Therefore, the study aims to verify the possibility of decentralized second-generation bioethanol production from regionally available agricultural residues. Most of the generated residues stem from the country's major crops (sugarcane, cassava, rice and palm), totaling 174.1 million tons per year. The volume of bioethanol from these residues is projected to be 20,213.5 million liters per year, meeting 31.2\% of the overall fuel demand of the transport sector. At the regional level, the northeast produces the highest amount of bioethanol at 9099.7 million liters per year, followed by the central, northern and southern regions. In terms of provincial distribution, the highest amount of bioethanol is converted in Nakhon Ratchasima, amounting to 1328 million liters per year. Data from the top ten potential provinces suggest that decentralizing production facilities is possible. One of the hotspots is Surat Thani in the south which can potentially utilize palm residues as feedstocks. This regionalized assessment also found that conventional feedstocks could be substituted with regionally available residues in the 26 production plants currently in operation. The results confirm that there would be enough alternative regional feedstocks to meet existing production capacities and they indicate that there would be enough regional residues left over for future value-added utilization. GRAPHICS
Background. Oil palm trunk (OPT) with highly cellulose content is a valuable bioresource for bioethanol production. To produce ethanol from biomass, pretreatment is an essential step in the conversion of lignocellulosic biomass to fermentable sugars such as glucose and xylose. Several pretreatment methods have been developed to overcome biomass recalcitrance. In this study, the effects of different pretreatment methods such as alkali pretreatment, microwave-alkali, and alkaline peroxide combined with autoclave on the lignocellulosic biomass structure were investigated. Moreover, ethanol production from the treated biomass was performed by simultaneous saccharification and cofermentation (SSCF) under different temperatures, fermentation times, and cell ratios of Saccharomyces cerevisiae NCYC 479 and pentose-utilizing yeast, Pichia stipitis NCYC 1541. Results. Pretreatment resulted in a significant lignin removal up to 83.26\% and cellulose released up to 80.74\% in treated OPT by alkaline peroxide combined with autoclave method. Enzymatic hydrolysis of treated OPT resulted in an increase in fermentable sugar up to 93.22\%. Optimization of SSCF by response surface method showed that the coculture could work together to produce maximum ethanol (1.89\%) and fermentation efficiency (66.14\%) under the optimized condition. Conclusion. Pretreatment by alkaline peroxide combined with autoclave method and SSCF process could be expected as a promising system for ethanol production from oil palm trunk and various lignocellulosic biomass.
The aim of this work was to study promotion of ball milling and CO2 assistance on cellulose hydrolysis kinetics in water medium. Kinetic behaviors were analyzed based on first-order and shrinking core models. The results showed that cellulose hydrolysis is enhanced by ball milling and CO2 assistance. Ball milling reduced crystallinity and particle size of cellulose, resulting in high cellulose conversion, while hydrolysis promoted by CO2 assistance was weaker. Double-layer hydrolysis was observed for ball-milled cellulose, and rate constant in active layer is higher. Based on double-layer shrinking core model (DL-SCM), activation energy of cellulose conversion decreased from 73.6 to 39.8 kJ/mol when ball milling and CO2 assistance were applied. Hydrolysis active layer was about 0.9 mu m, representing activated thickness of ball-milled cellulose. Hydrolysis promotion by crystallinity and particle size reduction was distinguished via DL-SCM, and crystal evolution possesses greater improvement than particle size decrease on hydrolysis of ball-milled cellulose.
BACKGROUND: Lignocellulosic biomass (LCB) offers the only sustainable alternative to the use of fossil fuels as oil by employing its main components (cellulose, hemicellulose and lignin) as a carbon source for the production of biofuels, energy and value added chemicals. The aim of the present study was to investigate ethanol production from organosolv pretreated Eucalyptus globulus wood, carrying out the simultaneous sacharification and fermentation (SSF) process at a substrate loading of 10 and 15\% (w/v) and using concentrations of 6 and 12 g L-1 of the thermally acclimatized S. cerevisiae IR2T9-a strain. These SSF experiments were also evaluated by increasing the enzyme loading in the reaction medium. Finally, a comparison was made between separate hydrolysis and fermentation (SHF) and SSF processes. With the information obtained and from published information, a general mass balance was developed. RESULTS: The highest ethanol concentration (similar to 42 g L-1) in the fermentation broth was obtained at a substrate consistency of 15\% (w/v), enzyme loading of 20 FPU cellulase 40 UI beta-glucosidase g(-1) of pretreated material and using both S. cerevisiae strain IR2-9a concentrations (6 and 12 g L-1). CONCLUSION: The results of enzymatic hydrolysis (EH) show that increasing substrate content from 10 to 15\% (w/v) decreases the conversion efficiency of cellulose to glucose. Furthermore, the mass balances of the process indicate that the SSF process is a better alternative than the SHF configuration, because larger amounts of ethanol can be obtained. (C) 2012 Society of Chemical Industry
Soil salinization is a growing threat to global agriculture and carbon sequestration, but to date it remains unclear how microbial processes will respond. We studied the acute response to salt exposure of a range of anabolic and catabolic microbial processes, including bacterial (leucine incorporation) and fungal (acetate incorporation into ergosterol) growth rates, respiration, and gross N mineralization and nitrification rates. To distinguish effects of specific ions from those of overall ionic strength, we compared the addition of four salts frequently associated with soil salinization (NaCl, KCl, Na2SO4, and K2SO4) to a nonsaline soil. To compare the tolerance of different microbial processes to salt and to interrelate the toxicity of different salts, concentration-response relationships were established. Growth-based measurements revealed that fungi were more resistant to salt exposure than bacteria. Effects by salt on C and N mineralization were indistinguishable, and in contrast to previous studies, nitrification was not found to be more sensitive to salt exposure than other microbial processes. The ion-specific toxicity of certain salts could be observed only for respiration, which was less inhibited by salts containing SO42 than Cl- salts, in contrast to the microbial growth assessments. This suggested that the inhibition of microbial growth was explained solely by total ionic strength, while ion-specific toxicity also should be considered for effects on microbial decomposition. This difference resulted in an apparent reduction of microbial growth efficiency in response to exposure to SO42- salts but not to Cl- salts; no evidence was found to distinguish K+ and Na+ salts.
Fed-batch method has shown a great promise in debottlenecking the high-solid enzymatic hydrolysis for the commercialization of cellulosic biosugar conversion for biofuel/biochemical production. To further improve enzymatic hydrolysis efficiency at high solid loading, fed-batch methods of green liquor-pretreated hardwood were performed to evaluate their effects on sugar recovery by comparing with one-stage batch method in this study. Among all the explored conditions, the fed-batch at 15\% consistency gave higher sugar recovery on green liquor-pretreated hardwood compared to that of one-stage batch. By using general linear model analysis, the percentage of enzymatic sugar recovery in fed-batch consistency method (increasing consistency from the initial 10.7 to 15\% at intervals of 24 and 48 h) was higher than that of batch hydrolysis at higher density of 15\% consistency. Under that best fed-batch condition, the total sugar recovery of pretreated hardwood in enzymatic hydrolysate reached approximately 48.41\% at CellicA (R) enzyme loading of 5 filter-paper unit (FPU)/g and 58.83\% at CellicA (R) enzyme loading of 10 FPU/g with a hydrolysis time of 96 h.
Background: As a natural renewable biomass, the tea oil fruit hull (TOFH) mainly consists of lignocellulose, together with some bioactive substances. Our earlier work constructed a two-stage solvent-based process, including one aqueous ethanol organosolv extraction and an atmospheric glycerol organosolv (AGO) pretreatment, for bioprocessing of the TOFH into diverse bioproducts. However, the AGO pretreatment is not as selective as expected in removing the lignin from TOFH, resulting in the limited delignification and simultaneously high cellulose loss. Results: In this study, acetic acid organosolv (AAO) pretreatment was optimized with experimental design to fractionate the TOFH selectively. Alkaline hydrogen peroxide (AHP) pretreatment was used for further delignification. Results indicate that the AAO-AHP pretreatment had an extremely good selectivity at component fractionation, resulting in 92\% delignification and 88\% hemicellulose removal, with 87\% cellulose retention. The pretreated substrate presented a remarkable enzymatic hydrolysis of 85\% for 48 h at a low cellulase loading of 3 FPU/g dry mass. The hydrolyzability was correlated with the composition and structure of substrates by using scanning electron microscopy, confocal laser scanning microscopy, and X-ray diffraction. Conclusion: The mild AAO-AHP pretreatment is an environmentally benign and advantageous scheme for biorefinery of the agroforestry biomass into value-added bioproducts.
Microalgal and lignocellulosic biomass is the most sumptuous renewable bioresource raw material existing on earth. Recently, the bioconversion of biomass into biofuels have received significant attention replacing fossil fuels. Pretreatment of biomass is a critical process in the conversion due to the nature and structure of the biomass cell wall that is complex. Although green technologies for biofuel production are advancing, the productivity and yield from these techniques are low. Over the past years, various pretreatment techniques have been developed and successfully employed to improve the technology. This paper presents an in-depth review of the recent advancement of pretreatment methods focusing on microalgal and lignocellulosic biomass. The technological approaches involving physical, chemical, biological and other latest pretreatment methods are reviewed.
A major challenge to commercial production of cellulosic ethanol pertains to the cost-effective breakdown of the complex and recalcitrant structure of lignocellulose into its components via pretreatment, the cost of enzymes for hydrolysis and fermentation, and the conversion rate of C5 sugars to ethanol, among others. While the industrialized and some emerging countries are gradually breaking grounds in cellulosic ethanol, most African countries have made little effort in research and development even though the continent is rich in lignocellulosic biomass. The paper estimates residues from widely available crops and municipal waste and determines their respective theoretical ethanol potential (around 22 billion litres annually). It further reviews stages involved in the production of cellulosic ethanol, focussing on processing methods that can be adapted to current situation in most African countries. The paper suggests that research and development should highlight favourable pretreatment methods such as extrusion, steaming/boiling, and chemical methods employing lime, KOH and crude glycerol (from biodiesel production), as well as the development of crude enzyme complexes from local materials. Though the falling price of enzymes is improving economic production of ethanol, advancements in heterogeneous catalytic hydrolysis will considerably favour economic production of ethanol in Africa due to the potential of recycling and reusing solid acid catalysts. (C) 2015 Elsevier Ltd. All rights reserved.
Over the past years, lack of energy fossil has become an important issue around the world, especially in developing countries such as Indonesia. Alternative energy is needed to replace utilization of fossil fuels. Bioethanol is providing one window of potential alternative energy. Lignocellulosic from oil palm empty fruit bunch (EFB) could be a promising bioethanol raw material because it will not interfere food supply. Pretreatment is a one of the steps in the bioconversion of lignocellulosic material. Pretreatment also contributed the largest cost in the bioethanol production. Black liquor as the waste of pretreatment provides significant environmental impacts. Black liquor recycling is expected to increase economic efficiency by reducing the cost of pretreatment and the amount of wastewater. This experiment used black liquor with NaOH addition as a pretreatment solution. The pretreatment process was conducted at 5 liter reactors at 150 degrees C and 160 degrees C. The result using black liquor was not significant different with using NaOH solution in the pretreatment process at 160 degrees C, delignification and cellulose content were 84.01\% and 77.10\%, respectively, but the results in pretreatment at 150 degrees C gave the lower value. The maximum ethanol concentration in variation of pretreatment solutions: NaOH solutions, black liquor with NaOH addition at 150 degrees C, and at 160 degrees C are 67.42 gl(-1), 61.14 gl(-1) and 67.03 gl(-1), respectively, at a pretreated biomass loading of approximately 15\% (w/v) with an enzyme dosage of 30 FPU g/dry biomass. (C) 2015 The Authors. Published by Elsevier Ltd.
Background Acquiring a good model is important for representing a real system especially in complex chemical processes. In this work, type-2 fuzzy logic with the Karmen-Mendel algorithm is proposed to model sequential ionic liquid dissolution-solid acid saccharification. The fuzzy calculation framework was regressed using a gradient descent technique to find the best fit model for a given data set with the target to achieve minimum integral square error (ISE) between predicted and experiment data. Results The regression results for both ionic liquid dissolution and solid acid saccharification were ISE 107.62 at a computational time of 907.35 s, and ISE 69.65 at 672.90 s, respectively. The high R-squared value of 0.98829 (ionic liquid dissolution) and 0.92585 (solid acid saccharification) indicated the good fit of the models. An optimum reducing sugars yield of 99.0\% at dissolution conditions: 1.5 h, 155 degrees C and 1.5\% substrate loading; and saccharification conditions: 1.5 h, 120 degrees C and 6\% catalyst loading, was achieved. Conclusion This study has demonstrated the good fit of a model for the sequential ionic liquid dissolution-solid acid saccharification process. The model developed has the potential to be used in predicting sugars production in the sequential ionic liquid dissolution-solid acid saccharification. (c) 2018 Society of Chemical Industry
The rice husk has the potential to be used for converting agricultural wastes into renewable energy. Therefore, this study aims to improve the hydrolysis of rice husk through Hydrogen Peroxide (HP) and Combined Hydrogen Peroxide-Aqueous Ammonia (CHPA) pretreatments. The removal of lignin from rice husks was determined using SEM-EDS examination of the samples. At a specific concentration of H2O2, (CHPA) pretreatment eliminated a significantly larger amount of lignin from biomass. The percentage of lignin removal of HP varied from 48.25 to 66.50, while CHPA ranged from 72.22 to 85.73. Hence, the use of batch kinetics of lignin removal of both pretreatments is recommended, where the kinetic parameters are determined by fitting the experimental data. Based on the results, the activation energies for HP and CHPA pretreatments were 9.96 and 7.44 kJ/mol, which showed that the24 model is appropriate for the experimental data. The increase in temperatures also led to a higher pretreatment value, indicating their positive correlation. Meanwhile, CHPA pretreatment was subjected to enzymatic hydrolysis of 6\% enzyme loading for the production of 6.58 g glucose/L at 25 h.
Formaldehyde-based resins are conventionally used as a binder in formulation of particleboard. Epidemiologic studies have shown that formaldehyde is carcinogenic. Efforts to reduce the health hazard effects of the fomaldehyde-based resin in the particleboard formulation have included use of scavengers for formaldehydes and use of an alternative binder. Use of scavengers for the formaldehyde increases the cost and maintenance of particleboard formulation. There is no proof that scavengers eliminate the emission of formaldehyde from particleboard. Use of biobased binders in particleboard formulation provides an alternative for eliminating use of the formaldehyde-based resin. However, the alternative is hindered by challenges, which include limitations of physical and mechanical properties. The challenge has continuously been acted upon through research. The paper presents an overview of the use of starch as an alternative binder. Improvement over time of the starch and limitations thereof requires to be addressed. Use of the modified starch has shown increased particleboard performance. Mechanical strength, such as modulus of rupture, modulus of elasticity, and internal bonding in particleboards, however, remains to be a challenge.
Enhancement of eucalyptus enzymatic saccharification by synergy of ZnCl2 hydrate pretreatment and bovine serum albumin (BSA) was investigated in this study. The result showed that the ZnCl2 hydrate pretreatment could not only selectively extract up to similar to 100\% of the hemicellulose from eucalyptus, but also convert portion of high crystalline cellulose I into low crystalline cellulose II, which both beneficial for enhancing subsequent pretreated solids enzymatic saccharification. The addition of BSA into enzymatic hydrolysis step could significantly promote the glucose release from pretreated solids, especially, under the low enzyme loading. Furthermore, the material balance indicated that the highest glucose yield of this study was 35.5 g/100 g raw material, which representing 90.3\% of glucose in raw eucalyptus, combined with the xylose yield, 13.9 g/100 g eucalyptus, it can be concluded that ZnCl2 hydrate pretreatment offered the potential to co-produce xylose and glucose from eucalyptus.
Mushroom cultivation waste material (MCWM) was utilized as a lignocellulosic source for cellulolytic enzyme production by Aspergillus tubingensis HS1-5 and bioethanol production. The appreciable level of cellulolytic enzymes was produced under a moisture content of 65\%, pH 5.0, and . Pretreatment of MCWM with 1\% at for 90 min was effective, resulting in high fermentable sugar yields. Enzymatic hydrolysis was performed using the substrate-to-enzyme volume ratios of 1:0.5, 1:1, and 1:2, and glucose concentration was maximal with the substrate-to-enzyme volume ratio of 1:0.5 at 24 h. The scanning electron microscope images indicated that acid pretreatment and enzymatic hydrolysis exerted the disintegration of MCWM structure and the release of fermentable sugars. The ethanol yield produced from MCWM by Saccharomyces cerevisiae TISTR 5339 was 0.42 g ethanol/g sugar, corresponding to 82.30\% of the theoretical yield. These findings suggest that MCWM is an appropriate lignocellulosic source for cellulolytic enzyme production and can be effectively used for bioethanol production.
In recent years, lignocellulosic biomass has drawn increasingly attention as a platform for its transformation into biofuels. However, the complex structures of lignocelluloses limit their conversion into fermentable sugars or other valuable products. In this work, a series of pyrrolidonium-based ionic liquids with a simple synthetic procedure were investigated for the pretreatment of corn stalk at 90 degrees C for 30 min. Both ionic liquids alone and ionic liquids with deionized water were studied. Fourier transform infrared spectroscopy (FTIR) analysis, scanning electron microscopy (SEM) analysis and nuclear magnetic resonance spectroscopy (NMR) analysis were employed to determine the chemical characteristics of regenerated lignin or cellulosic feedstock. A significant yield of lignin was achieved, as high as 19.07\%, which accounted for 85.94\% of the original lignin of corn stalk. A high yield of reducing sugar (91.81\%) was obtained from regenerated cellulosic feedstock after enzymatic hydrolysis. High yields of glucose (79.63\%) and cellobiose (13.66\%) were observed as determined by high performance liquid chromatography (HPLC). (C) 2016 Elsevier B.V. All rights reserved.
Cellulose was extracted from durian rind using delignification with acidic sodium chlorite then followed by mercerization with 17.5\% (w/v) sodium hydroxide. Gas pycnometer indicated that density of extracted cellulose was 1.59 g/cm(3). Fourier transform infrared (FTIR) confirmed the removal of non-cellulosic components. The micrograph by scanning electron microscopy (SEM) displayed non-fibrous components scattered over the surface of durian rind were removed. Most of cellulose presented a diameter and aspect ratio in the range of 100 - 150 mu m and 20 - 25, respectively. In the future, cellulose from durian rind has a potential to be used as a reinforcement elements in composite materials. (C) 2014 The Authors. Published by Elsevier B.V.
In this study, a Eucalyptus by-product was fractionated into cellulose and lignin by pretreatment with NaClO2 to obtain alpha-cellulose, and hydrothermal pretreatment followed by sulfite-NaOH to obtain cellulose and lignin. The recovered celluloses were chemically and structurally characterized and enzymatically hydrolyzed using commercial enzyme preparations. The alpha-cellulose and cellulose treated with sulfite-NaOH had cellulose contents of 70.1\% and 61.1\%, respectively. alpha-cellulose hydrolyzed with Celluclast showed potential for cello-oligosaccharides formation, resulting in a maximum conversion of 30\%, while Cellic CTec 2 resulted in 100\% conversion to glucose, whereas cellulose treated with sulfite-NaOH showed potential for conversion to glucose with Cellulcast (44\%) and Cellic CTec 2 (78\%). The liquor from the sulfite-NaOH process resulted in a 20.8\% yield of sulfonated lignin recovery. The use of different pretreatment techniques for the Eucalyptus by-product can be alternatives for the generation of products with high added value and commercial potential, such as cello-oligosaccharides, glucose, and sulfonated lignin.(c) 2022 Elsevier Ltd. All rights reserved.
The article shows the possibilities of solid-state (CP MAS) C-13 NMR spectroscopy for determination of lignin content in a wide range of lignocellulosic materials: wood of various tree species and plant waste. The analysis is based on the use of the dependences of the integral intensity of C-13 NMR signals due to aromatic or methoxy carbon atoms of lignin on its percentage in mixtures with cellulose. The lignin content obtained by C-13 NMR spectroscopy is in good agreement with the published data and the results obtained using acid hydrolysis of the corresponding samples of lignocellulosic biomaterials.
Reactive extraction is gaining higher attention due its wide application in various solute separation processes. Here, a mathematical model of reactive extraction in slab has been proposed. The model was developed by considering simultaneous processes of active compound intra particle diffusion, second order elemental reaction of solute-active compound, and intra-particle product diffusion. The obtained partial differential equations (PDEs) were solved using Finite Difference Approximation (FDA) method by using realistic parameters. Concentration profile as well as product yield were evaluated as a function of time. As a result, the model proposed here may serve as a basis design for reactive extraction unit. Sensitivity analyses was conducted to inspect the influence of slab thickness, diffusivity and reaction rate constant to the product yield. Eventually, model validation was conducted by comparing the simulation results with analytical solutions for special cases. Validation results showed that the model gave good agreement with the analytical solution.
The high loading of lignocellulosic substrates could merge the advantages of solid-state and submerged fermentations. However, high solid loading in bioreactors could result in oxygen mass transfer complications and caused extra waste of inlet air. In this work, the effects of Brewer's Spent Grain (BSG) loading on enzyme production, oxygen transfer rate (OTR) and carbon dioxide evolution rate (CER) were investigated at 50, 75 and 100 g L-1 BSG in a 2.5-L stirred tank bioreactor. However, in small-scale bioreactor, the short contact time and inadequate mixing of bubbles in liquids affected the OTR and gas holdup negatively. Therefore, xylanase production in a 14-L vessel with 100 g L-1 BSG has been studied. In a larger bioreactor, a remarkable improvement in OTR and a significant reduction in total air consumption were recorded. Furthermore, the enzyme production per 1 L of consumed air was four times greater than 2.5-L vessels. As a result, the energy consumption for aeration was less in the larger bioreactor with high solid loading. Additionally, the residual xylan content monitoring during enzyme production has revealed that the BSG's xylan content decreased in the first 12 h of cultivation and then it remained approximately constant that probably means further xylanase induction is influenced by the concentration of BSG's hydrolysis products. Concisely, it seems that initial higher solid loading could be used as a practical alternative to solid substrate feeding during the fermentation. These findings would be useful for the fermentation of high loading lignocellulosic material in the industrial-scale bioreactor.
Pretreatment of lignocellulosic biomass by N-methylmorpholine-N-oxide (NMMO), a solvent used in the textile industry to dissolve cellulose for production of regenerated cellulose fibers, was observed to enhance significantly enzymatic saccharification and fermentation. The enhancement was speculated to have been caused by reduced cellulose crystallinity after dissolution and precipitation processes. This work focused on assessing several physical changes and their correlations to enzymatic saccharification of pine flour after NMMO pretreatment. Results from microstructure, surface chemical composition, and cellulose accessibility complementarily illustrated the enrichment of cellulose on pine flour surface after NMMO pretreatment. Cellulose accessibility was highly correlated to the overall glucan conversion rate. Changes in crystallinity were correlated to the initial hydrolysis rate but not overall glucan conversion rate. Findings from this work may contribute to lignocellulosic bioenergy from development of novel pretreatment technologies utilizing NMMO.
Poly(acrylic acid) hydroxyethyl cellulose {[
The interacting effects of N, P, and S limitation were investigated by applying four different organic components, i.e., cysteine, chitosan, glucose-6-phosphate, and glucose, to a soil at two different clearly defined N, P, and S levels in a 5-fold range, one with sufficient and one with limited nutrient supply. Initially, MB-CN, MB-CP, and MB-CS ratios were lower after organic substrate amendments with the higher concentration of N, P, and S. The close relationship between the nutrient supply and elemental MB ratios was strongly modified within the next 14days for the MB-CN ratio, probably due to a strong shift in the microbial community composition towards fungi, determined by the ergosterol content of soil. This shift was promoted by high N and low P and S availability, contrasting the view that S is important for the formation of fungal biomass. However, the negative interactions between P limitation and MB-CS ratio suggest that the microbial S metabolism has specific importance under P-limiting conditions. Low substrate CN ratio increased carbon use efficiency (CUE) by 20\% in comparison with high substrate CN ratio, calculated at day 5, solely due to an increased formation of microbial residues, as the formation of MBC was not affected by differences in substrate CN ratio. In contrast, high substrate CP and CS ratios reduced MBC formation but did not affect CUE values.
Lignocellulosic biomass is an attractive raw material for the production of bioethanol because of its abundance and cheapness, but due to its complex structure the enzymes can penetrate the substrate and obtaining the fermentable sugars from the cellulose is a slow process. As indicated above, lignocellulosic biomass has to pass pretreatments to enhance the enzymatic saccharification. Dilute acid and alkaline H2O2 pretreatments show promises to cheapen the process, making the scaling to industrial stage possible. The optimum conditions for the dilute acid pretreatment were time, 33 min, and acid concentration of 1.56\% v/v, obtaining a xylose yield of 89.9\% and removing 83.2\% of hemicellulose. The alkaline H2O2 pretreatment obtained a glucose concentration of 62.4 g/L with 5\% H2O2, liquid:solid ratio 13.47:1 and time 20.7 h. Tween 80 increased the global glucose yield at 87\% with 0.3\% w/v of Tween and 5-h contact time. The dilute acid pretreatment removed 83\% of the hemicellulose in corncob and the alkaline H2O2 pretreatment 56.8\% of lignin, obtaining 71\% of glucose yield. Finally, Tween 80 increased 19\% of global glucose yield.
In this study the adsorption of New Methylene blue (Basic blue 24) on sawdust of Malus domestica was investigated. The sawdust was chemically treated to enhance the adsorption capacity. Adsorption experiments were performed at different temperatures ranging from 20-40 degrees C on both raw and treated sawdust samples. The residual concentration of the dye was determined by UV-Vis spectrophotometric technique. Effect of various reaction parameters like temperature, initial dye concentration, equilibration time and pH was studied. Sawdust was characterized by BET, FTIR, Scanning electron microscopy (SEM), and Energy dispersive spectroscopy (EDS) techniques. Adsorption kinetics was interpreted using intra particle diffusion and Bangham models and both models were found to best describe the sorption of New Methylene blue onto M. domestica. Thermodynamic parameters like Delta E degrees, Delta H degrees, Delta S degrees and Delta G degrees were calculated from the adsorption kinetics data. The data show that the adsorption is an endothermic process. The negative value of entropy shows that the dye molecules take an oriented position on the adsorbent surface. Adsorption data fitted well with Langmuir, Freundlich and Temkin adsorption isotherms. All results clarify that M. domestica sawdust is a useful cheap adsorbent for removing basic dyes.
Three wine-making residues (grape seeds, skins and stems), and corn cobs were evaluated as support material for immobilization of Saccharomyces cerevisiae and the ethanol production by the immobilized cells was assessed. The main objective of this study was to find an abundant and low cost material suitable for the cells immobilization and able to be used in a next step of wine production by immobilized yeast cells. The four natural materials were used as support in two different forms: untreated, and treated by a sequence of acid and basic reactions. Untreated grape skin and corn cobs provided the highest cell immobilization results (25.1 and 22.2 mg cells/g support, respectively). The maximum ethanol production yield (about 0.50 g/g) was also obtained when the cells were immobilized in these untreated materials. It was also found that the support materials released nutrients to the medium, which favored the yeast development and the ethanol production. The use of immobilized cells systems under agitated conditions gave ethanol yields similar to those obtained by the static fermentations, but the immobilized cell concentration was significantly lower. In brief, static fermentation with cells immobilized on grape skins or corn cobs appear to be an interesting alternative for use on wine-making. The use of grape skins, particularly, which is a by-product of the wine elaboration, could be of larger interest to obtain an integrated wine production process with by-product reuse. (C) 2011 Elsevier B.V. All rights reserved.
The valorization of organosolv pretreatment (OP) is a required approach to the industrialization of the current enzyme-mediated lignocellulosic biorefinery. Recent literature has demonstrated that the solvolysis happening in the OP can modify the soluble components into value-added active compounds, namely organosolv modified lignin (OML) and organosolv modified sugars (OMSs), in addition to protecting them against excessive degradation. Among them, the OML is coincidental with the ``lignin-first{''
Nanocellulose is a unique and promising natural nanomaterial and has gained significant attention due to its applications in several important areas. Thus, researchers are continuously looking for the most efficient, sus-tainable, economically viable, and environmentally friendly production technologies to fulfil its growing de-mand. Conventional production technologies, which include various physical, chemical, and physicochemical methods, are currently inadequate for this purpose and have several limitations such as long processing time, high energy consumption, low recovery of nanocellulose, and many others. To overcome these shortcomings, scientists have investigated the prospect of utilizing emerging processing technologies such as microwave irra-diation, deep eutectic solvent, enzymatic processing, cold plasma, electron beam irradiation, and pulsed electric field in nanocellulose preparation. In general, studies have shown that the application of emerging technologies enhances the extraction yield and properties of nanocellulose. This article presents a review of the most recent works reported on the application of emerging technologies in nanocellulose production.
Moderate pretreatment methods were evaluated on oil palm empty fruit bunches (OPEFB) in order to obtain xylose-rich hydrolysate for xylitol production via enzymatic hydrolysis and fermentation. Assessments on the effects of catalysts (autohydrolysis/water, acetic acid, or ammonia) and the corresponding concentration and pretreatment time at moderate pressure/temperature were conducted while the process performance was evaluated by enzymatic hydrolysis. Most hemicellulose was still retained in the pretreated solid at the evaluated pretreatment conditions, hydrolysis of both the pretreated solid and spent liquor are necessary to obtain most of xylose from OPEFB. Pretreatment using 5\% ammonia gave the highest xylose yield; however, great amount of acid would be needed for pH adjustment for the following enzymatic hydrolysis process and thereby autohydrolysis was preferred. The optimum yield was obtained from autohydrolysis at 1.5 barg/127.9 degrees C for 60 min, which gave xylose yield of 0.085 g xylose/g OPEFB (or 39.1\% of hemicellulose). The obtained hydrolysate could be directly used as substrate for fermentation.
Microfibrillated cellulose (MFC) from Argan (Argania spinosa) shells was prepared by chemical purification of cellulose, then mechanical disintegration via high pressure homogenization was performed to isolate fibrils of cellulose. Chemical characterization of raw argan shell (AS-R), purified cellulose (AS-C), and argan shell MFC (AS-MFC) included FT-IR, XRD and NMR. Morphological characterization of AS-MFC was assessed using TEM. Next, the use of AS-MFC as oil-in-water (O/W) emulsions stabilizer was investigated. The particle concentration was observed to affect the long-term stability of the emulsions; high concentrations (0.5-1 \% w/w) of AS-MFC resulted in emulsions that were thermodynamically stable during 15 days of storage, which was demonstrated by the droplet's size evolution. The suitable oil concentration for a maximum volume of emulsion using 1 \% w/w AS-MFC was demonstrated. The results show that AS-MFC is able to stabilize 70 \% w/w MCT oil without visual phase separation. Finally, CLSM shows the adsorption of AS-MFC at the oil-water interface and the formation of a 3D network surrounding oil droplets, confirming Pickering emulsion formation and stabilization.
Pb (II) is one of the toxic heavy metal ions, which is released from the industry, especially the manufacture of batteries and electronics-devices. Its release into the water effluents causes environmental problems and affects the humans' and animals' health. Adsorption is one of the conventional techniques for removal of Pb (II) in water treatment processes. The adsorbents with effective adsorption properties with their easy operation are then desired. In this study, hierarchically porous carbon monoliths with magnetic properties have been designed and successfully fabricated by incorporating sodium alginate and black liquor in ferric chloride solution. The resulting monoliths have been used to study their adsorption efficiency towards Pb (II) in aqueous solution. The interconnected macroporous structures of the materials were generated by the freeze-drying process, while the increase in microporosity was observed after pyrolysis at 700 degrees C (SA-BL-Fe-700). SA-BL-Fe-700 showed a magnetization of 8.79 emu/g, and high porosity, with a BET specific surface area of 945.45 m(2)/g and pore size distribution calculated by DFT was less than 2 nm, which is suitable to adsorb Pb (II) ions. Furthermore, the materials obtained showed a monolith feature in a cylindrical shape with strong mechanical stability, which renders them with the easy operation. The adsorption properties of SA-BL-Fe-700 monolith toward Pb (II) ions demonstrated a maximum adsorption capacity of 75.19 mg/g at pH 5 with retaining the magnetic properties. The study of adsorption behaviours illustrated that equilibrium data and kinetic study fitted with Langmuir isotherm model and pseudo-second-order model, respectively.
Sophorolipids (SLs) are biosurfactants with widespread applications. The yield and purity of SLs are two important factors to be considered during their commercial large-scale production. Notably, SL accumulation causes an increase in viscosity, decrease in dissolved oxygen and product inhibition in the fermentation medium. This inhibits the further production and purification of SLs. This describes the development of a novel integrated system for SL production using Candida albicans O-13-1. Semicontinuous fermentation was performed using a novel bioreactor with dual ventilation pipes and dual sieve-plates (DVDSB). SLs were separated and recovered using a newly designed two-stage separation system. After SL recovery, the fermentation broth containing residual glucose and oleic acid was recycled back into the bioreactor. This novel approach considerably alleviated the problem of product inhibition and accelerated the rate of substrate utilization. Production of SLs achieved was 477gl(-1), while their productivity was 1.59gl(-1)h(-1). Purity of SLs improved by 23.3\%, from 60\% to 74\%, using DVDSB with the separation system. The conversion rate of carbon source increased from 0.5gg(-1) (in the batch fermentation) to 0.6gg(-1). These results indicated that the integrated system could improve the efficiency of production and purity of SLs.
The aim of present research was to study the pyrolysis of wood sawdust in a semi batch reactor and explored the influence of pyrolysis process parameters on the products yield. Pyrolysis process parameters such as temperature, heating rate, nitrogen (N-2) flow rate and particle size of wood sawdust were varied as 350-650 degrees C, 10 and 50 degrees C/min, 50-200 cm(3)/min and <0.25 to >1.7 mm, respectively. The maximum bio-oil yield was found as 44.16 wt\% at temperature of 500 degrees C, heating rate of 50 degrees C/min and nitrogen flow rate of 100 cm(3)/min for particle size range of 0.6 < d(p) < 1 mm. The composition and characteristics of bio-oil and bio-char were determined. Different methods such as ultimate analysis, Fourier transformed infrared spectroscopy (FTIR), Gas chromatography-mass spectroscopy (GC-MS), and Nuclear magnetic resonance spectroscopy (H-1 NMR) were used to characterize bio-oil. Boiling point range of bio-oil was found in between 63 and 360 degrees C. Bio-char and original biomass were analyzed by physicochemical, thermogravimetric as well as analytical methods using sophisticated instruments such as Field emission scanning electron microscope (FESEM), and X-ray diffractometer (XRD). (C) 2019 Published by Elsevier Ltd.
The utilization of lignocellulosic biomass to produce fuels and chemicals is an effective way to gradually relieve the global threats of petroleum exhaustion and climate change. However, the recalcitrant nature and complex structure of biomass have become the biggest obstacle for utilization during the bioenergy conversion processes. Steam explosion, a mild and fast treatment process integrating the high-temperature autohydrolysis and structural disruption by explosive decompression, has been proven as an effective, environment-friendly and industrially scalable method for biomass pretreatment, which can significantly improve the fuel properties and processability of the feedstock, for several bioenergy conversion techniques. This article aimed at reviewing the impact of steam explosion pretreatment on the bioenergy conversion processes and product properties. Based on those findings in the literature, a steam explosion step is beneficial to subsequent conversion processes of biomass, including densification, hydrolysis, fermentation, pyrolysis and gasification, by improving biomass properties such as durability, heating value and cellulose accessibility. Improved yields and properties of final products in solid (e.g. pellet fuel, biochar), liquid (e.g. bio-oil, bioethanol, biobutanol) and gaseous (e.g. syngas, biogas) states were also analyzed. Overall, this review provided a historical and comprehensive understanding of how the steam explosion benefits the subsequent bioenergy conversion process and product quality.
Bioethanol is the alternative to fossil fuels for the transport sector's environmental sustainability. Scientific journals have disclosed a few works on modeling and enhancing bioethanol production processes. To industri-alize these production processes, however, the modeling requires consideration for mass and heat transfer, mainly when applying intensification machinery. Consequently, CFD is preferable to a comprehensive analysis of fluids. Computational fluid dynamics (CFD) configure the flowing progress of bioethanol production, the flow pattern distribution curve, and flow pattern visualization. This article reviews recent advances in CFD Modeling of bioethanol production processes in conventional and newly designed bioethanol production technologies, such as simultaneous saccharification and fermentation (SSF) and membrane bioreactor. None of other studies addressed a kinetic model of the fermentation process in the SSF and membrane bioreactors. For the design of new (SSF) and membrane bioreactors, CFD and its combination with other simulation software might deliver a wealth of useful data. The first section of this paper addresses the bioethanol production process of the second generation: pretreatment, enzymatic saccharification, and fermentation. The second section of this review dis-cussed hydrodynamics, reaction kinetics, and bioreactor design, focusing on CFD models of the bioethanol production technology. A conclusion and a recommendation, this section concludes with a discussion of insights into unexplored areas of study and challenges in modeling bioethanol production processes.
In the present study, yard waste was pretreated by thermo-chemo-sonic pretreatment prior to anaerobic digestion to improve its anaerobic biodegradability. First, the pretreatment conditions were optimized using Box-Behnken design based response surface methodology for the maximum organic matter solubilisation. Then, the possible mechanism of delignification by thermo-chemo-sonic pretreatment was discussed. Moreover, the anaerobic digestion performance of untreated yard waste (UYW) and pretreated yard waste (PYW) was compared. The optimum pretreatment condition based on the increase in soluble COD and volatile solids (VS) was: 2997 kJ/kgTS ultrasonic energy, 74 degrees C, and 10.1 pH. The highest methane yield of 374 +/- 28 mL/gVS(added) for the PYW at the optimum condition was achieved, which was 37.5 \% higher than the UYW (272 +/- 16 mL/gVS(added)). Finally, the environmental impacts associated with anaerobic digestion of both UYW and PYW were compared. The life cycle assessment confirmed a positive environmental impact of pretreatment.
Liquid hot water (LHW) pretreatment is considered as a key step in reducing biomass recalcitrance and improving its accessibility to microorganisms during anaerobic digestion. In the present study, a comprehensive comparison among hot air oven, hot water bath, autoclave and microwave (MW) pretreated yard waste (YW) was conducted. The effect of treatment temperature and duration for all the four LHW pretreatment techniques were optimized with respect to the organic matter solubilisation. The results showed that all four LHW pretreatment techniques have a positive effect on organic matter solubilisation. The highest organic matter solubilisation was found in case of MW pretreatment for a treatment duration of 100 s at a temperature of 140 degrees C. Therefore, batch biochemical methane potential (BMP) of untreated and MW pre-treated YW was carried out for this treatment condition. The BMP of MW pretreated YW resulted in an improvement in methane yield to 364.5 +/- 11 mL/g VS on 26th day of anaerobic digestion, which was 1.1 times higher than that of untreated (328.9 +/- 15 mL/g VS on 45th day of anaerobic digestion). The FTIR and XRD analysis confirmed that LHW pretreatment technique removed amorphous constituents due to the polymerization of polysaccharides present in YW. In addition, SEM analysis confirmed that the LHW pretreatment led irregular and distorted structure of biomass which improved cellulose accessibility to anaerobic bacteria. A positive energy balance confirmed the possible applicability of MW pretreatment in real life projects.
Biorefining of second-generation feedstock gains more attention to improve the living standards and promote circular bioeconomy. The biorefinery concept made an effort to make the environmentally sustainable and economical products. Lignocellulosic biomass is widely available and extensively tested feedstock to produce biofuels, bioenergy and different value- products. By the integration of process to fractionate the lignin, cellulose and hemicellulose can add more values in the process chain that required integration and optimized technologies followed by life cycle analysis and economic assessment. The life cycle and economic analysis together assess the impacts on environment, economic and all the impacts which are involved indirectly throughout the product stages from cradle to grave. The improvement and integration of the current biorefinery process recommends the newer and sustainable bio-economy and will replace the fossil fuels with the renewable reserve. In technoeconomic perspective, the optimization of integrated technologies for the production of biofuels and other bioproducts have still to be optimized for efficient production. The proper adoption of pretreatment methods increases the economic value in biorefinery process. The main aim of this review is to summarize the three key research areas that required more attentions, they are; (a) valorization of lignin, cellulose, hemicellulose into value added products, (b) integrated biorefinery approach and process optimization; and (c) circular bioeconomy and its future perspective. This review concludes that the lignocellulosic integrated biorefinery approach is feasible to support the circular bioeconomy, through which number of value products could be derived.
Five types of pretreatment processes were investigated to confirm the enhancement of the enzymatic hydrolysis of poplar. These processes included a hot water pretreatment, a calcium oxide pretreatment, NaOH extraction at low temperature, a Fenton reaction, and a combined dilute NaOH and Fenton pretreatment. The combined dilute NaOH and Fenton pretreatment was found to be the most effective pretreatment process. After enzymatic hydrolysis for 72 h, 74\% of the cellulose recovery yield was obtained when the poplar substrates were pretreated with 2\% NaOH at 75 degrees C for 3 h, followed by 20 mmol/g of H2O2 (30\%) and 0.2 mmol/g of FeSO4 center dot 7H(2)O for a Fenton reaction period of 12 h. The cellulose recovery yield was approximately five-fold greater than that of the untreated sample directly processed by enzymatic hydrolysis. Furthermore, microscopic observations of changes in the surface structure of the pretreated residue were correlated with the enhancement of the enzymatic hydrolysis of cellulose. In conclusion, the combined dilute NaOH and Fenton pretreatment shows high potential for future application.
Lignocellulosic biomass resources especially agricultural and forests residues, perennial crops, farm wastes, and the organic fraction of municipal solid waste hold significant potential for the widespread production of sustainable fuels, chemicals, and bioproducts worldwide. For biochemical conversion processes, deconstruction of lignocellulosic biomass into its components (cellulose, hemicellulose, and lignin) for further microbial conversion has been a major challenge due to the recalcitrant nature of lignocellulose. Thus pretreatment is prerequisite for efficient hydrolysis of lignocellulose and cost for such treatment is currently about one third of the overall processing costs in a cellulosic biorefinery. Thus, the development of a more efficient and cost-effective pretreatment method is crucial for the commercialization of lignocellulosic biorefineries. Wet explosion (WEx), a thermochemical pretreatment method with additional features of oxygen addition and explosive decompression, can be adjusted to different biomass feedstock and to subsequent bio-catalytic and microbial processes. The WEx pretreatment method has been successfully applied in combination with both microbial fermentation and anaerobic digestion processes using both agricultural and forest residues as well as manure fibers. Steam explosion, represents a related process to WEx pretreatment where high pressure is used but no oxygen is added. This process has been tested in demonstration scale while WEx is on its way to commercialization. Presented here is a summary of the basic concepts and parameters involved in WEx pretreatment.
Corn cobs are major byproduct of maize processing industries. For value addition of maize byproducts, the present paper aims at extracting xylan from corn cobs and subsequent production of xylooligosaccharides (XOS). Compositional determination of corn cobs revealed 38.78\% hemicellulose, 27.71\% cellulose and 9.4\% lignin. Recovery of xylan increased with increasing concentration of alkali during extraction. The extracted xylan was subjected to acidic hydrolysis to yield XOs. HPLC analysis of hydrolysate revealed increased production of XOS with time, but prolonged incubation resulted in higher amount of xylose. Four probiotic strains were used for undertaking in vitro evaluation of the prebiotic efficacy of XOS. XOS ensured higher growth rate for Enterococcus faecium as compared to other probionts, while fructooligosaccharides (FOS) supported higher proliferation of Lactobacillus viridiscens. This method of xylan extraction and production of XOS offers scope for value addition to the corn byproducts. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Jerusalem artichoke (JA) is a potential energy crop for biorefinery due to its unique agronomic traits such as resistance to environmental stresses and high biomass yield in marginal lands. Although JA tubers have been explored for inulin extraction and biofuels production, there is little concern on its stalk (JAS). In this article, the pretreatment of JAS by alkaline hydrogen peroxide was optimized using the response surface methodology to improve sugars yield and reduce chemicals usage. Scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis were applied to characterize the structures of the pretreated JAS to evaluate the effectiveness of the pretreatment. Furthermore, the feeding of the pretreated JAS and cellulase was performed for high solid uploading (up to 30\%) to increase ethanol titer, and simultaneous saccharification and fermentation with 55.6 g/L ethanol produced, 36.5\% more than that produced through separate hydrolysis and fermentation, was validated to be more efficient. (C) 2016 Elsevier Ltd. All rights reserved.
Lignocellulosic biomass residues constitute an alternative for energy generation. In this work, brewery spent grain (BSG) were used as feedstock to produce ethanol using a recombinant Escherichia coli MS04 strain. A sequential process involving pretreatment, saccharification and fermentation steps in one-pot bioreactors, without solids removal, was proposed. Different diluted acid pretreatment times (1 and 1.5 h) using a 15\% (w/w) solids load to obtain high monosaccharides yields were evaluated. After the pretreatment and saccharification, the proposed strategy converted the polysaccharides contained in BSG into fermentable pentoses and hexoses, obtaining a syrup composed by monosaccharides (60 g/L), furfural (0.39 g/L), hydroxymethylfurfural (0.07 g/L) and acetic acid (2.56 g/L), which was afterwards fermented for the bioethanol generation. After 30 h, ethanol production resulted in 29.5 +/- 0.41 g/L, which means a volumetric productivity of 0.98 g EtOH/Lh based on the consumption of the glucose, xylose and arabinose. These results mean a global yield of 251 L EtOH/ton BSG of this feedstock and were accomplished without the inhibition caused by acetic acid formation (6.87 g/L). Furthermore, the proposed process in this work was developed in a sequential pathway, which comprises an operational advantage to exploit the BSG in the production of second-generation bioethanol.(c) 2022 Elsevier Ltd. All rights reserved.
The use of industrial waste for the production of biomass is a topic that has gained increasing interest. This is due to the need to use plants that do not affect the food supply when used for power generation from biomass. Agave salmiana residues meet these characteristics. It has now been proposed as a possible source of bioenergy production because of its growth characteristics. Therefore, in this research, the effect of combustion temperature of the A. salmiana as it could happen in the energy production was studied. In addition, the characteristics of these residues were analyzed to serve as a basis for possible future applications in construction materials. Results indicate that the ashes are mainly CaCO3 when calcined at below 700 degrees C, and CaO above this temperature. The apparent particle size was between 25 and 32 mu m. However, it is observed that it consists of much smaller particles of approximately 300 nm. This reduction in size is related to decomposition at higher temperatures and is reflected in the increase of the specific area up to 70\%. The compression strength at early ages was up to 90\% higher than a reference, when 5\% cement replacement mixes were performed. (C) 2015 Elsevier B.V. All rights reserved.
Monitoring the influence of livestock systems' on soil quality (SQ) in the Colombian Amazon region is important to ensure the sustainability of those agroecosystems. Here we used the Soil Management Assessment Framework (SMAF) to assess the SQ responses to land-use change associated with the adoption of silvopastoral systems (SPS) at two study sites in the Colombian Amazon region. A chronosequence formed by three land-use systems, reflecting the typical land transition performed in the region, was established at each study site: i) native vegetation (NV), ii) pasture (PAST), and iii) SPS. Soil samples were collected at 10 cm deep increments until reaching 30 cm deep. Then soil pH, potassium, available phosphorus, microbial carbon, soil organic carbon, and bulk density were measured. In addition, data from Visual Evaluation of Soil Structure (VESS) were correlated. Data were interpretated using SMAF algorithms, and a Soil Quality Index (SQI) was calculated. Our data showed an SQ degradation due to land-use change from NV to PAST, with soils reducing their capacity of soils function from 0.72 to 0.62. The establishment of SPS over extensive PAST restored soil quality (SQI = 0.69) compared to PAST (both sites), even reaching similar SQI values to those observed in NV at site 1. The SMAF showed to be a potential tool to monitor the SQ in low-fertility soils from the Colombian Amazon region. The VESS scores were also correlated with SMAF - scores, proving to be a simple and complementary tool for farmers to monitor SQ in the Amazon region.
Butyl methacrylate (BMA) was grafted onto kapok fiber using benzoyl peroxide (BPO) as initiator. The structure of the grafted kapok was investigated using Fourier transform infrared spectroscopy and scanning electron microscopy. The results illustrated that BMA was successfully grafted onto the kapok fiber surface. The effects of monomer concentration, temperature and time on the oil absorbency of grafted kapok fiber were investigated. The oil absorbencies of raw kapok, NaClO2-treated kapok fiber and kapok-g-butyl methacrylate were evaluated and compared. Compared with raw kapok fiber, grafted kapok fiber showed the highest oil absorbency, with the increase percentage of 63.4\%, 42.5\% and 56.4\% for chloroform, toluene and n-hexane, respectively. Furthermore, the as-developed grafted kapok fiber exhibited excellent reusability, and can be utilized as an eco-friendly material for recovering oil released into the surroundings.
A large volume of wood waste is produced in timber processing industry which traditionally used in low value applications. Here, value addition to the wood waste (Sander dust) and cellulose, hemicellulose isolated thereof by functionalisation using cyclic anhydrides in a solvent-free and green reactive extrusion process is reported. The effect of extrusion temperature, catalyst and different weight ratios of Sander dust (SD):succinic anhydride (SA) on the esterification reaction is evaluated. The esterified products were characterised by the acid value, degree of substitution (DS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), solid state C-13 NMR and thermo-gravimetric analysis (TGA). Under optimum extrusion conditions, mixed esters are formed, with highest acid value obtained for succinylation of cellulose (0.122 g/g at DS of 0.350) which is two times higher compared to succinylated SD (0.059 g/g at a weight gain of 0.452) and hemicellulose (0.043 g/g at DS of 0.290). The reactivity trend for individual anhydride was: (1) SA - Cellulose> SD > hemicellulose; (2) maleic anhydride (MA) SD > hemicellulose >cellulose and (3) dodecenyl succinic anhydride (DDSA) SD approximate to cellulose >> hemicellulose. The pendant free carboxyl groups generated through functionalisation of wood waste, cellulose and hemicellulose without the presence of polymeric carriers will allow more tailored or targeted modification of wood-plastic composites. (C) 2015 Elsevier Ltd. All rights reserved.
A combined process was designed for the co-production of ethanol and methane from unwashed steam-exploded corn stover. A terminal ethanol titer of 69.8 g/kg mass weight (72.5\%) was achieved when the fed-batch mode was performed at a final solids loading of 35.5\% (w/w) dry matter (DM) content. The whole stillage from high-solids ethanol fermentation was directly transferred in a 3-L anaerobic digester. During 52-day single-stage digester operation, the methane productivity was 320 mL CH4/g volatile solids (VS) with a maximum VS reduction efficiency of 55.3\%. The calculated overall product yield was 197 g ethanol + 96 g methane/kg corn stover. This indicated that the combined process was able to improve overall content utilization and extract a greater yield of lignocellulosic biomass compared to ethanol fermentation alone. (C) 2014 Elsevier Ltd. All rights reserved.
BACKGROUND: Barley husks were subjected to non-isothermal autohydrolysis of different severities, yielding a liquid phase rich in hemicellulose-derived compounds and a solid phase, composed mainly of cellulose and lignin. This solid phase was subjected to enzymatic hydrolysis in order to assess the effects of severity on the susceptibility of substrates to enzymatic hydrolysis. The effects of the liquid to solid ratio (LSR, in the range 6 to 189 g(-1)) and cellulase to substrate ratio (CSR, in the range 3.3 to 8.2 FPU g(-1)) on the enzymatic hydrolysis were assessed. RESULTS,: Up to 25.8,g oligomers per 100 g raw material were present in liquors from the hydrothermal processing. Enzymatic hydrolysis of solid phases obtained under selected conditions (log Ro = 4.14, LSR = 6 g g(-1) and CSR = 5.8 FPU g(-1)) yielded glucose concentrations up to 679 L-1 (corresponding to cellulose to glucose conversions close to 100\%). CONCLUSION: It was shown that autohydrolysis is an effective method for improving the enzymatic susceptibility of barley husks. High cellulose conversions resulting in high glucose yields were achieved by enzymatic hydrolysis at low LSR and CSR. The liquid fraction obtained upon autohydrolysis contained large amounts of hemicellulose-derived compounds. (C) 2010 Society of Chemical Industry
Organosolv fractionation is a promising process to separate lignocellulosic biomass for the preparation of multiply products including biofuels, chemicals, and materials. This review presents the state of art of different processes applying alcohols and organic acids to treat lignocellulosic biomass for the production of ethanol, lignin, xylose, etc. The major organosolv technologies using ethanol, formic acid, and acetic acid, are intensively introduced and discussed in depth. In addition, the structural modifications of the major components of lignocelluloses, the technical processes, and the applications of the products were also summarized. The object of the review is to provide recent information in the field of organosolv process for the integrated biorefinery. The perspectives of the challenge and opportunity related to this topic are also presented. (C) 2015 Elsevier Ltd. All rights reserved.
Prosopis juliflora (Mesquite) is a raw material for long-term sustainable production of cellulosics ethanol. in this study, we used acid pretreatment, delignification and enzymatic hydrolysis to evaluate the pretreatment to produce more sugar, to be fermented to ethanol. Dilute H2SO4 (3.0\%, v/v) treatment resulted in hydrolysis of hemicelluloses from lignocellulosic complex to pentose sugars along with other byproducts such as furfural, hydroxymethyl furfural (HMF), phenolics and acetic acid. The acid pretreated substrate was delignified to the extent of 93.2\% by the combined action of sodium sulphite (5.0\%, w/v) and sodium chlorite (3.0\%, w/v). The remaining cellulosic residue was enzymatically hydrolyzed in 0.05 M citrate phosphate buffer (pH 5.0) using 3.0 U of filter paper cellulase (FPase) and 9.0 U of beta-glucosidase per mL of citrate phosphate buffer. The maximum enzymatic saccharification of cellulosic material (82.8\%) was achieved after 28 h incubation at 50 degrees C. The fermentation of both acid and enzymatic hydrolysates, containing 18.24 g/L and 37.47 g/L sugars, with Pichia stipitis and Saccharomyces cerevisiae produced 7.13 g/L and 18.52 g/L of ethanol with corresponding yield of 0.39 g/g and 0.49 g/g, respectively. (C) 2008 Elsevier Ltd. All rights reserved.
The adsorptive removal of hexavalent chromium Cr(VI) from aqueous solutions was investigated by acrylonitrile grafted banana peels (GBPs). Banana peels were treated with 10\% HCl, followed by alkaline hydrolysis with 10\% NaOH, and washed thoroughly. The bleaching of alkali hydrolyzed peels was carried out with sodium chlorate (NaClO3) in the presence of hydrogen peroxide and glacial acetic acid. The grafting co-polymerization of acrylonitrile onto the bleached pulp was initiated by Fenton's reagent (Fe+2/H2O2). The optimum conditions for adsorption of Cr(VI) were found to be the following: pH 3, adsorbent dose 4 g/L, concentration 400 mg/L and contact time of 120 min. The surface morphology of adsorbent was characterized by scanning electron microscopy (SEM) before and after the adsorption. The adsorption of Cr(VI) onto grafted banana peels (GBPs) was recorded to be 96\%. The adsorption data were fully fitted with the Freundlich and Langmuir isotherm model and followed a pseudo-second order kinetic model. Thermodynamic study showed that the adsorption is exothermic and spontaneous. Owing to high efficiency and low cost, grafted banana peels (GBPs) can be used as effective adsorbent for Cr(VI) removal from wastewater. (C) 2016 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Cellulose nanocrystals (CNCs) were successfully isolated from marine biomass of brown, red, and green seaweeds by a four step process of de-polymerization, bleaching, acid hydrolysis, and mechanical dispersion. Chemical composition, yield, and density were determined for each seaweed group and compared to other cellulose sources. Morphological analysis was performed by transmission electronic microscopy (TEM) and showed that CNCs from seaweed showed rod shape particles 21-248 nm length and 4.8-41 nm width. The obtained aspect ratio was varied from 2.5 to 15. Fourier transform infrared spectroscopy (FTIR) analysis was performed to investigate chemical structure of CNCs from seaweeds, which revealed obtained crystalline cellulosic from the extraction process. X-ray diffraction (XRD) data showed the main crystalline structure of CNCs was cellulose I in all cases. The crystalline index increased about 21.5\% going from cellulose to CNCs. The thermal properties of untreated seaweeds, extracted cellulose, and CNCs were compared by thermogravimetric analysis (TGA). The onset thermal decomposition (T-on) increased in all cases and weight loss changes significantly decreased during the extraction process except Sargassum fluaans, indicating the thermal stability of CNCs.
Over the past decades, most studies with xylanases have used Birchwood xylan as the standard substrate for activity assays. However, recently, Birchwood xylan production was discontinued by major suppliers, creating an important demand for a substitute. Ongoing and future studies require a substrate with characteristics equivalent to the discontinued xylan, in order to enable the comparison of results. In this context, a protocol for the production of a substrate similar to the discontinued commercial Birchwood xylan is reported. Obtained from bleached Eucalyptus cellulose pulp, xylan was extracted using 4\% w/v NaOH solution at 25 degrees C, precipitated with glacial acetic acid (HOAc), and freeze-dried. A thermal pretreatment in an autoclave for 15 min increased its solubility. The resulting xylan was characterized by infrared spectroscopy, thermogravimetry, and NMR. When assessing the activity of xylanases, the results were the same as those for commercial Birchwood xylan.
Chinese chive, a famous green vegetable, is widely cultivated in the Asia. In the present study, we found that ultrasound caused the degradation of Chinese chive polysaccharides (CCP) in the process of extraction. Since lacking the consideration of polysaccharide degradation, the traditional kinetic models can not reflect the real extraction process of CCP. Therefore, a modified kinetic model was thus established by introducing a parameter of degradation coefficient based on the Fick's second law, suggesting the diffusion and degradation of CCP is highly dependent on the ultrasonic power, extraction temperature and solid-liquid ratio. According to this modified model, the maximum CCP yield was obtained under an optimal extraction condition including extraction temperature 37 degrees C, ultrasonic power 458 w, extraction time 30 min and solid-liquid ratio 1:32. The objective polysaccharides responding to ultrasound were shown to be four different fractions, contributing to the increased diffusion and degradation of CCP by ultrasound treatment. (C) 2016 Elsevier Ltd. All rights reserved.
Medium-density fiberboard (MDF) is commonly used for furniture manufactured. The increase in demand and the short relative lifecycle have increased the generated waste volume, increasing concerns about disposal. Despite being mainly composed of input from a renewable source, very little of this material is recycled. In this sense, this aim article performed a literature overview of MDF recycling technologies presenting the challenges and perspectives to overcome this problem. The relevant articles considered for this review were selected from the Web of Science and the Scopus databases. The first step for MDF recycling is its disintegration, which inevitably changes the properties of the wood fibers from MDF waste. Allied with this, the other constituents, like resin, are a challenge to a recycling process that, a priori, is more appropriately carried out only with fibers. Ideally, it would be recycling the MDF in new panels, however, due to the mentioned issues, it is not possible in its entirety, and in a continuous way (in several recycling cycles). As MDF waste is a material with caloric capacity during combustion, converting it to energy is a possibility, especially when other more sustainable alternatives are difficult. An emerging alternative is the pyrolysis and enzymolysis of MDF to obtain valued products. Further studies are needed, both for the disintegration processes to preserve the characteristics of the MDF fibers and the other constituents together with the MDF to favor its recycling. It is lacking evaluation of the economic, and principally environmental issues of each recycling alternative.
Because of its non-toxic, pollution-free, and low-cost advantages, environmentally-friendly packaging is receiving widespread attention. However, using simple technology to prepare environmentally-friendly packaging with excellent comprehensive performance is a difficult problem faced by the world. This paper reports a very simple and environmentally-friendly method. The hydroxyl groups of cellulose nanofibrils (CNFs) were modified by introducing malic acid and the silane coupling agent KH-550, and the modified CNF were added to cassava starch as a reinforcing agent to prepare film with excellent mechanical, hydrophobic, and barrier properties. In addition, due to the addition of malic acid and a silane coupling agent, the dispersibility and thermal stability of the modified CNFs became significantly better. By adjusting the order of adding the modifiers, the hydrophobicity of the CNFs and thermal stability were increased by 53.5\% and 36.9\% 2.7\%, respectively. At the same time, the addition of modified CNFs increased the tensile strength, hydrophobicity, and water vapor transmission coefficient of the starch-based composite films by 1034\%, 129.4\%, and 35.95\%, respectively. This material can be widely used in the packaging of food, cosmetics, pharmaceuticals, and medical consumables.
In response to the scarcity of non-renewable energy sources, sustainable and renewable biofuels from biomass have gained utmost attention. Utilization of lignocellulosic biomass for production of varied energy forms (second generation fuels) like biogas, biodiesel, bioethanol, etc has increased in the past decade. Their properties of being naturally abundant and easily accessible throughout the year, makes them an attractive energy alternative. Efficient pretreatment techniques for effective transformation of lignocelluloses to varied products, by increasing digestibility of celluloses and hemicelluloses can be achieved through acid, alkali treatment, enzymatic hydrolysis, and steam explosion. Idea behind optimizing pretreatment protocol is to maximize release of monosaccharide sugars for conversion to valise added products. Tailoring of hydrolytic enzymes through various approaches is well accepted for increasing specific activity of particular enzymatic reaction and can also be clubbed with other pretreatment processes minimizing chemical usage. We at our laboratory are working on optimization of process parameters for enhancing efficiency of saccharification process to obtain maximal monosaccharide sugars that can be converted to bioethanol. Present review compiles various approaches made by prominent scientists for efficient utilization of celluloses and hemicelluloses for ethanol production and also describes recent advanced techniques utilized for the same. Greater emphasis has been led on comparative study on utilization of simple sugars by bacteria and fungi and effect of consolidated bioprocess system on ethanol production from varied agro-industrial wastes.
In this study, agricultural residue from black oat, a cover crop usually grown to improve soil nutrients between the periods of regular crop production, was used as a source of cellulose fibers. Concentrations of 1, 3, and 5 wt. \% of regenerated cellulose (RC) fibers blended in poly(vinyl alcohol) (PVA) solution were used to prepare the reinforced composite films (CFs) by the solvent cast method. Compared to neat PVA film (control), the effects of RC addition on functional properties of CFs, such as water absorption, transparency, thermal stability, and mechanical property were investigated. All CFs with different RC concentrations exhibited improved mechanical property and thermal stability while the swelling property was decreased, and no significant changes were observed in the film transparency as compared with the control film. Among the CFs, films with 3\% RC significantly decreased water vapor transmission rate, swelling, and soluble fraction (p < 0.05). In addition, Young's modulus and tensile strength were increased by 40 MPa and 3 MPa, respectively, while elongation at break was decreased by 4\%, compared to the control film. The results indicate that RC from black oat might be feasible as potential bio fillers to improve film properties in a bio-based composite matrix.
A procedure for the alkaline pretreatment of sisal fiber assisted by ultrasound was optimized to obtain a higher solubilization of hemicellulose and the removal of lignin with cellulose fraction maintenance. A full factorial design 2(3) was used for the evaluation of the effects of the variables (sonication time, NaOH concentration, and sonication amplitude) on the pretreatment. The optimal values for the variables using the Doehlert matrix for the sonication time, NaOH concentration, and sonication amplitude were 27 min, 4.1\% (m/v), and 50\%, respectively. The X-ray diffractometry and scanning electron microscopy analyses, after pretreatment, showed changes in chemical structure and morphology due to the removal of 82\% of hemicellulose and 86\% of lignin from sisal fiber. The soft reaction conditions and relatively short times demonstrated the effectiveness of the combined action of ultrasound with alkaline pretreatment to improve the accessibility to cellulose in this important step of the ethanol production process from biomass.
The present study evaluated the purification of inulinase by changing the ionic strength of the medium by addition of NaCl and CaCl2 followed by precipitation with n-propyl alcohol or iso-propyl alcohol. The effects of the concentration of alcohols and the rate of addition of alcohols in the crude extract on the purification yield and purification factor were evaluated. Precipitation caused an activation of enzyme and allowed purification factors up to 2.4-fold for both alcohols. The purification factor was affected positively by the modification of the ionic strength of the medium to 0.5 mol.L-1 NaCl before precipitation with the alcohol (n-propyl or iso-propyl). A purification factor of 4.8-fold and an enzyme yield of 78.1 \% could be achieved by the addition of 0.5 mol.L-1 of NaCl to the crude extract, followed by the precipitation with 50 \% (v/v) of n-propyl alcohol, added at a flow rate of 19.9 mL/min.
Alkaline pretreatment can effectively remove lignin and significantly increase enzymatic hydrolysis efficiency of lignocellulosic biomass. Sodium hydroxide (NaOH) is the common alkali for treating lignocellulose. However, a large quantity of liquid waste (LW) generated in the NaOH pretreatment process is hard to be removed. In this context, this work employed KOH together with urea for treating corn stover (CS) and explored the feasibility of recovering LW for plant fertilization due to the existence of potassium (K) and nitrogen (N) elements in LW. With response surface methodology, an optimum pretreatment condition, which was 1:1 (2\% w/v) Urea/KOH (UK) at 30 degrees C for 2 h was achieved. Enzymatic digestibility of UK-treated CS could attain 75.49\%, which was 12.55\% higher than that of KOH-treated CS under the same conditions. The glucose yield could be further increased to 83.1\% with the addition of 1\% Tween-80. Meanwhile, the LW showed significant enhancement in the length and biomass yield of two cereal and three vegetable crops. UK pretreatment is a promising greenway for cellulosic ethanol production by recycling LW as value-added fertilizer. (C) 2020 Elsevier Ltd. All rights reserved.
The two red seaweeds, Gracilaria manilaensis and Kappaphycus alvarezii are cultivated in Malaysia for producing agar and carrageenan, respectively. The residues of these seaweeds after removing agar and carrageenan by dilute acid treatment were subjected to enzymatic hydrolysis using cellulase (Cellic CTec 2). In the optimization of enzymatic hydrolysis, highest glucose concentration was achieved in the sample with liquid: residue ratio of 7.5:1 and enzyme loading of 10 \% w w(-1) residue. The resulting glucose was converted to bioethanol using Saccharomyces cerevisiae where bioethanol yields from G. manilaensis and K. alvarezii were 56.26 +/- 1.10 g L-1 and 51.10 +/- 1.21 g L-1 , respectively, which corresponded to 91 \% and 95 \% of the theoretical yield. The results of this study indicate that the residues of these seaweeds can be efficiently converted to bioethanol and besides environmental benefits, additional profit can be achieved in the phycocolloid industry.
Fractional pretreatment of lignocellulose is compelling to synergistically enhance its carbohydrate and lignin outputs for the extension of renewable energy sources. A two-stage approach using hydrothermal and ionic liquid (1-butyl-3-methylimidazoliumacesulfamate, {[
BACKGROUND Lignocellulosic biomass is a promising renewable feedstock to obtain fuels and chemicals. However, a suitable pretreatment is required to separate its main components and overcome its structural resistance to enzymatic hydrolysis. In this work, a sequential pretreatment composed of autohydrolysis (AH) and organosolv delignification (ORG) is used to fractionate Pinus radiata wood and improve the enzymatic hydrolysis. RESULTS The effect of three different AH pretreatment severities on the delignification degree of organosolv solid fractions was evaluated. In addition, enzymatic hydrolysis was performed to determine the efficiency of the combination of pretreatments. The results showed that a pretreated solid with high cellulose content (88\%, w/w) and high delignification degree (88\%) was achieved under mild conditions of AH (150 degrees C and 30 min) and acid-catalyzed ORG (185 degrees C, 75 min, 50\% (w/w) ethanol and 1\% (w/w) sulfuric acid), obtaining an enzymatic hydrolysis yield of 63\%. CONCLUSION This study provides the most favorable conditions to fractionate a softwood, P. radiata, employing a two-step pretreatment based on AH followed by ORG. (c) 2019 Society of Chemical Industry
To enhance the hydrophobicity and thermal stability of hemicelluloses for the production of functional biopolymer, hemicelluloses was homogeneously butyrylated with butyryl chloride in 1-butyl-3-methylimidazolium chloride ({[
Spent coffee grounds (SCG) are a promising raw material for galactomannan (GalM) production based upon its enrichment in galactomannan polysaccharides. In this work, SCG was pretreated by autohydrolysis for maximumly improving GalM extractability by endo-mannanase. The GalM in the prehydolyzate (GalM-PH) and enzymatic hydrolyzate (GalM-EH) were obtained by ethanol preripitation and characterized. Under the optimized autohydrolysis conditions, 50.1\% of GalM in pretreated SCG was converted into free GalM in enzymatic hydrolyzate. Compositional analysis results revealed that GalM-PH was comprised of 81.7\% galactomannan, higher than that of GalM-EH (76.4\%). The molecular weight of GalM-PH and GalM-EH were 44.5 kDa and 28.0 kDa, respectively. Antioxidant assays indicated that both GalM-EH and GalM-PH could scavenge 2.2-diphenyl-1-picryl-hydrazyl radicals and hydroxyl radicals. Immunological and prebiotics analysis showed all GalM preparations exhibited pronounced activities for proliferating the probiotics and proliferating the Macrophages cell for NO production, in which the GalM-EH outperformed the GalM-PH. These results imply that the GalM extracted from SCG are the bioactive substances that can be used as antioxidant, prebiotics, and immunostimulants. (C) 2020 Elsevier B.V. All rights reserved.
Cellulose nanofibers were produced with waste from the paper industry, in a stone grinder and were used as filler in elastomeric composites in the acrylonitrile-butadiene copolymer (NBR). Two different cellulose mass concentrations (0.5 and 2.0 wt\%) were ground in water and incorporated in concentrations of 0, 10 and 20 phr by the coagulation of the NBR, followed by drying. The other components of the formulation were incorporated and vulcanized in an open mixer and molded by compression. Due to the proposed grinding it was possible to obtain nanocellulose, in the range of 20.5 nm to 83.6 nm at an average diameter of 42.8 nm for the solution produced with 2.0 wt\% and 18.3 nm at 90.5 nm at an average diameter of 44.3 for the solution with 0.5 wt\%. The composites with a 20 phr of nanofiber presented lower vulcanization times and better mechanical properties before and after accelerated aging for 7 days, as well as a superior resistance to gasoline and diesel than the NBR and the samples with 10 phr. A tear strength of 61 N.mm(-2) was obtained at the concentration of 20 phr and 0.5 wt\% of incorporated nanofibers in line with a shorter vulcanization time.
Landfill leachate was treated by a process involving use of sludge-based activated carbon (SBAC) combined with a membrane bioreactor (MBR), which reduced cost compared to traditional activated carbon. The MBR process was operated to compare the membrane fouling characteristics for exploring effects of the properties and amount of added SBAC on membrane fouling. Influences of extracellular polymeric substances (EPS) and soluble microbial products (SMP) on the transmembrane pressure (TMP) were illustrated based on the contents and components of EPS and SMP in sludge mixed liquor and on the membrane surface. Results showed that the EPS, SMP, proteins, and polysaccharides in sludge mixed liquor of the SBAC-MBR first increased and then decreased with the operation time, and accumulation of EPS, proteins, and polysaccharides on the membrane surface in the SBAC-MBR increased gradually with time during the operational cycle. TMP in the SBAC-MBR first increased gradually and then decreased exponentially during the operational cycle. Addition of SBAC to the MBR reduced the amounts and changed the compositions of EPS and SMP, which improved the properties and structure of the cake layer on the membrane surface and decreased membrane fouling. During the operational cycle, the period of slow increase of TMP in the reactor was prolonged by adding SBCA, which extended the cleaning cycle of the membrane module from 17 to 21 days.
Complete cycle of ethylene production from oat hulls as widespread agricultural waste was studied on a pilot scale. The cycle involved mechano-chemical, biotechnological and catalytic units. The oat hulls were pretreated with a 2\%(w/w) sodium hydroxide solution in a setup consisting of a rotary-pulsating apparatus and a 100-L vessel to produce a pulp containing 90.3\% of hydrolyzables. Simultaneous saccharification and fermentation of oat hull pulp with delayed inoculation (dSSF) into ethanol using commercial enzymes CelloLux-A and BrewZyme-BGX and non-GMO yeast Saccharomyces cerevisiae was carried out in 63-L reactor. At a solid loading of 33.3 g/L, the yield of reducing sugars was 97.9\% on overall hydrolyzables basis. The ethanol yield during dSSF at a solid loading of 60 g/L was as high as 95 g ethanol/kg oat hulls. The produced raw-ethanol sample contained low impurities of methanol, propanol and alkali metals. The rectified ethanol samples were used for dehydration to ethylene with the overall production index as high as 38-51 g ethylene/kg oats hulls. A negative impact of the propanol and alkali metals impurities in the rectified ethanol on conversion and selectivity to ethylene were observed. Being purified from organic impurities, ethanol was dehydrated with higher conversion and selectivity to ethylene. When the ethanol samples that contain less than 0.02 g/L organic and no sodium impurities were used in ethanol dehydration process, the yield of ethylene was as high as 56 g ethylene/kg oats hulls. In this work, 12 kg of oat hulls was converted to 1.21 kg 94\%(w/w) ethanol, which was then converted to 0.62 kg 99.5\% ethylene; this is the first experimental study devoted to the production of ethylene from oat hulls on a pilot scale. (C) 2017 Elsevier B.V. All rights reserved.
The use of mild pretreatment conditions can significantly lower the cost of the biorefining process. This study evaluated a mild pretreatment approach for tobacco stem waste using a combination of dilute acid and dilute alkali. By optimizing the pretreatment conditions, we obtained a high reducing sugar concentration at a pretreatment temperature < 100?. Increasing the acid or alkali strength in a single pretreatment step did not always improve the result; instead, the synergistic effect of both pretreatment components was important. To increase the bioethanol titer, a high solid loading, 30\%, was used for bioethanol fermentation. Compared with batch fermentation, enzyme feeding with a shorter feeding period (24 h) enhanced the bioethanol production by 4.32\%, generating 86.88 g/L bioethanol. The results provide valuable insights into the effects of two-step acid/alkali pretreatment on enzymolysis. The findings suggest that the optimized synergistic pretreatment process is efficient for bioethanol fermentation.
Enzymatic hydrolysis of lignocellulose for bioethanol production shows a great potential to remit the rapid consumption of fossil fuels, given the fact that lignocellulose feedstocks are abundant, cost-efficient, and renewable. Lignin results in low enzymatic saccharification by forming the steric hindrance, non-productive adsorption of cellulase onto lignin, and deactivating the cellulase. In general, the non-productive binding of cellulase on lignin is widely known as the major cause for inhibiting the enzymatic hydrolysis. Pretreatment is an effective way to remove lignin and improve the enzymatic digestibility of lignocellulose. Along with removing lignin, the pretreatment can modify the lignin structure, which significantly affects the non-productive adsorption of cellulase onto lignin. To relieve the inhibitory effect of lignin on enzymatic hydrolysis, enormous efforts have been made to elucidate the correlation of lignin structure with lignin-enzyme interactions but with different views. In addition, contrary to the traditional belief that lignin inhibits enzymatic hydrolysis, in recent years, the addition of water-soluble lignin such as lignosulfonate or low molecular-weight lignin exerts a positive effect on enzymatic hydrolysis, which gives a new insight into the lignin-enzyme interactions. For throwing light on their structure-interaction relationship during enzymatic hydrolysis, the effect of residual lignin in substrate and introduced lignin in hydrolysate on enzymatic hydrolysis are critically reviewed, aiming at realizing the targeted regulation of lignin structure for improving the saccharification of lignocellulose. The review is also focused on exploring the lignin-enzyme interactions to mitigate the negative impact of lignin and reducing the cost of enzymatic hydrolysis of lignocellulose.
In the pursuit of the 7th Sustainable Development Goal (SDG) of the United Nations, it is driven to develop affordable, sustainable, and clean energy. Second (lignocellulosic) and third (microalgae and macroalgae) generation bioethanol appear to be the most favorable renewable feedstocks to meet SDG 7 pursuance. However, several feedstock pretreatments have shown process challenges in terms of yield and product inhibitors. Microwave-assisted heating (MAH) has gained positive attention as a novel alternative method for pretreatment heating in the global community due to its numerous advantages over conventional heating. Therefore, current studies and progress in MAH pretreatment for bioethanol production are critically reviewed. The effects of different parameters on MAH pretreatment are also examined. The application of MAH pretreatment demonstrates rapid reaction exhibiting remarkable improvement in sugar recovery and fewer inhibitors over conventional heating. Despite these advanced results, certain obstacles remain to be addressed and improved until it is ready for industrial scalability. It includes understanding the interaction and relationship between the different parameters like biomass loading, catalysts, temperature, power intensity, contact time, and pressure for reactor design. Moreover, factors such as the non-thermal effect, dielectric properties of different biomass materials, and controlled temperature need to be further explored and evaluated. Thus, continuous research and development efforts on MAH pretreatment are encouraged to become commercially feasible for the applications of bioethanol production.
Each year different agricultural plants are cultivated in the world for human nutrition, livestock feed, and industrial applications, a considerable part of which is lost to sub-standard planting and harvesting, incorrect processing and pests. This work aimed to study the potential use of date wastes as a source of bioethanol production as well as its adapted conversion technologies and economic assessment of fuel production process in the world. About 10-50\% of produced dates are wasted annually, depending on the country, which could be converted to biofuels. In the present study, the latest technologies are introduced and updated for ethanol production from date wastes (DWs). Three scenarios of ethanol production and electricity generation (EEG), ethanol production and heat generation (EHG), ethanol production and bio-material making (EBM) from DWs were designed. Moreover, three types of primary energy (ethanol, electricity, and CNG) can be considered for DWs. For this, direct sugar fermentation, direct gasification, pre-treatment-hydrolysis-fermentation (SHF), and pre-treatment-saccharification/cofermentation-fermentation (SSF) can be effective. Accordingly, the worldwide annual potential is 3260 million litres of ethanol. According to our estimation, the cost of ethanol production from the date feedstock varies between 0.34 and 0.68 USD per litre, depending on the country. (C) 2019 Elsevier Ltd. All rights reserved.
The objective of this research was to investigate the potential damage caused by the residual concentrations of the insecticides Regent (R) WS 800 and Curbix (R) SC 200, containing fipronil and ethiprole, respectively as active ingredients, on the liver of Oreochromis niloticus. The analyses of HSP70 shock protein labelling and cell death process by TUNEL method were performed in order to measure the effects of the exposure of cell repair system of fish to both insecticides. Statistical analyses showed no significant molecular damage to the hepatic tissue of animals. Nevertheless, variations in HSP70 and DNA fragmentation levels, endpoint of cell repair system response and cellular death, respectively, were observed in several groups. These results indicate that the cell repair machinery was efficient when in contact with residual concentrations of insecticides. However, the DNA fragmentation detected by the TUNEL method suggests that even in face of the cytoprotective action of the HSP70 protein, there are damages that become irreparable. To finish, it is worth mentioning that given the results obtained from residual concentrations, use in the field should be with caution.
This study simulated the application of the continuous multiple tube reactor (CMTR), a promising technology capable to replace fixed-film reactors in biohydrogen (bioH(2)) production via dark fermentation, in the processing of sucrose-rich wastewater (COD of up to 16 g L-1). The long-term impacts on both the bioH(2) evolution and the dynamics of biomass growth and retention were assessed, aiming to identify the operating limits of the reactor. The bioH(2) production was maximized (1445 NmL H-2 L-1 d(-1)) when using moderately concentrated wastewaters (COD = 8 g L-1) at an OLR of 48.0 g COD L-1 d(-1), with much lower hydrogenogenic activity (< 200 NmL H-2 L-1 d(-1)) observed at OLR levels of 72.0 and 96.0 g COD L-1 d(-1). Inhibition of the fermentative activity by excess substrate and limitations in the retention capacity of suspended biomass in the reactor still limit the application of higher OLR at the current stage of the technology. Strategies stimulating the cell growth (nitrogen dosing) and biofilm formation (calcium dosing) have potential to expand the operating limit of the CMTR without requiring constructive modifications.
The aim of this work is to show the potential of guava seeds (agro-industrial waste) for obtaining pyrolytic sugar like levoglucosan by fast pyrolysis. Firstly, guava seeds were ground to 30 mesh and then subjected to fast pyrolysis in a pyro-probe reactor coupled to GC/MS at temperatures of 350-600 degrees C. Thus, in addition to the production of levoglucosan, it was possible to verify the formation profiles of different compounds derived from cellulose, hemicellulose and lignin which may also add value to biomass or be undesirable in the extraction and purification stages of these sugars. Simultaneously, the seeds were subjected to a treatment with acetic acid to leach alkali and alkaline earth metals and to increase the formation of levoglucosan, achieving a yield at 550 oC after acid washing that was around 14 times higher than that obtained with untreated biomass. These results can be attributed not only to the reduction in K, Mg and Ca but also to the partial removal of fractions of hemicellulose and lignin during the biomass acid washing, thus resulting in a higher cellulose content in the treated biomass. In fact, TG/DTG analyses confirmed that the treated biomass is more thermally stable and that there was a reduction in residual biochar from 23 to 19\%, thereby having more cellulose available for levoglucosan formation. The results of this study can contribute to the production of renewable fuels from alternative feedstocks and at the same time add value to the agribusiness of commercialization and processing of guava.
This paper focused on extraction of cellulose nanofibrils (CNFs) from coconut (Cocos nucifera L.) palm petioles falling off naturally, which if not properly processed constitute an environmental hazard. CNFs were isolated by chemical pretreatments and different mechanical processing, including grinding (G), grinding followed by ultrasonication (GU), and grinding followed by homogenization (GH). As one of the applications of this biodegradable and renewable CNFs, fabrication of films without using an organic solvent has been attempted using the received CNFs. Fourier transform infrared spectroscopy (FTIR) spectra analysis showed that the chemical treatment removed most of hemicellulose and lignin from the palm petioles, remaining only cellulose. SEM observations showed that diameter of the CNFs from GU method was between 50 and 100 nm, and the aspect ratio of CNFs was over 1000. Tensile properties and transmittance of CNFs films with different mechanical treatments were also studied. Compared to grinding treatment, the CNFs film prepared by grinding/ultrasonication and grinding/homogenization treatments presented better tensile properties and transmittance. This work provides a new approach for more effective utilization of coconut palm petiole as potential feedstock for CNFs. (C) 2014 Elsevier B.V. All rights reserved.
Camellia oleifera shells (COS), are the by-product of Camellia oleifera seed oil processing, and possess a high lignin content (38.6\%). However, information on the fundamental chemistry of this lignin is limited. Herein, mecha-nochemical strategies combining ball-milling with mild acetosolv or alkaline treatment are presented to compare the structural evolution of COS lignins. The mechanochemical processes significantly improve the lignin yield, releasing lignins with high molecular weights (Mw approximate to 7000 mol/g). The COS lignins are GS-type lignins, and G units account for 71.9\% of MWL. The synergistic combination of ball-milling and acetosolv treatment led to the cleavage of beta-O-4 linkages. In contrast, the alkaline lignin fractions retained a large number of beta-O-4 linkages (50.67/100 Ar) and a low phenolic OH content (1.56 mmol/g), indicating that the ball-milling process had little effect on the alkaline lignin structures (typical substructures). In summary, understanding the structural con -version and characteristics of lignins during the combined pretreatments of COS would facilitate the optimization of the pretreatment process and the deconstruction of COS.
Wood-feeding termites effectively degrade plant biomass through enzymatic degradation. Despite their high efficiencies, however, individual glycoside hydrolases isolated from termites and their symbionts exhibit anomalously low effectiveness in lignocellulose degradation, suggesting hereto unknown enzymatic activities in their digestome. Herein, we demonstrate that an ancient redox-active enzyme encoded by the lower termite Coptotermes gestroi, a Cu/Zn superoxide dismutase (CgSOD-1), plays a previously unknown role in plant biomass degradation. We show that CgSOD-1 transcripts and peptides are up-regulated in response to an increased level of lignocellulose recalcitrance and that CgSOD-1 localizes in the lumen of the fore- and midguts of C. gestroi together with termite main cellulase, CgEG-1-GH9. CgSOD-1 boosts the saccharification of polysaccharides by CgEG-1-GH9. We show that the boosting effect of CgSOD-1 involves an oxidative mechanism of action in which CgSOD-1 generates reactive oxygen species that subsequently cleave the polysaccharide. SOD-type enzymes constitute a new addition to the growing family of oxidases, ones which are up-regulated when exposed to recalcitrant polysaccharides, and that are used by Nature for biomass degradation.
Nettle is a cellulosic plant fiber with a reasonably large lumen and they are a cheap, easily renewable source of fibers with the potential for oil absorbency. To the author's best knowledge, there are no published data available on the oil absorbency behavior of alkali-treated nettle fibers. In this work, alkali treatment on nettle fibers was carried out with a view to improve their oil absorbency. The effects of treatment time, temperature, concentration, and solid: liquor ratio of nettle fibers on oil absorbency was assessed. As compared to raw nettle fibers, the oil absorbency of alkali-treated nettle fibers was considerably higher. Nettle fibers were also characterized by FTIR, TGA, SEM, and reusability tests. Oil absorbency capacity of alkali-treated nettle fibers has also been compared with other natural materials.
It is generally recognized that the front-end (pretreatment, fractionation, enzymatic hydrolysis) steps of a lignocellulose-to-ethanol process are both technologically immature and represent a large component (similar to 60\%) of the total product cost. Tn the past, we have tried to itemize the process steps and equipment for a complete plant. It was evident that, owing to the complexity and interrelated nature of this process, it was difficult to determine the influence of even minor changes to the process on the overall production cost of the product. We had originally developed a techno-economic model, based on spreadsheets, as a computational and assessment tool. However, our more recent work, which has looked at various process options such as hardwood vs softwoods, SO2 pretreatment of softwoods, and enzyme recycling, indicated that the model required greater flexibility if it was to assess a `'generic'' biomass-to-ethanol process. The model is currently being modified to address both the flexibility issues, through the incorporation of flowsheeting concepts, as well as including the most recent work on the various process options. in this article, we have described some of the pretreatment and fractionation issues that are being addressed in the updated model.
Chemical, physical and mineralogical characterization of an industrial rice husk ash is reported and the differences with ash typically obtained by laboratory combustion of husks were highlighted. Valorization of industrial ash was targeted by controlling the combustion temperature of rice husks at 600 degrees C, 650 degrees C, 700 degrees C and 750 degrees C in an atmospheric fluidized bed industrial boiler of a paper mill. The other parameters were ash sampling points (air-preheater, economizer and electrostatic-precipitator) and the ash processing condition (as-received and ground). Irrespective of the burning temperature or sampling point, all ashes had a cellular microstructure with a high specific surface area (25 m(2)/g - 50 m(2)/g), silica content was greater than 80\% with the amorphous fraction being larger than 90\%. Pozzolanic reactivity of ground ash for the entire burning temperature range of 600 degrees C -750 degrees C was acceptable and a 15\% replacement of cement with the processed ash in blended mortars yielded optimum strength and flow performance.
To assess the impacts of biochar application on crop productivity and global warming mitigation, a 4-yr field experiment was conducted in a well-drained Andosol in northern Japan. Wood residue-derived biochar (pyrolyzed at >800 degrees C) was applied at rates of 0, 10, 20, and 40 Mg ha(-1) for potatoes, winter wheat, sugar beet, and soybeans cultivated in rotation, and CO2, N2O, and CH4 emissions from the soil and yield and quality of the harvested materials were measured. Biochar application, regardless of rate, had no significant impact on yield and quality of the harvested materials, except for soybean grain yield. It also had no effect on cumulative CO2, N2O, and CH4 emissions from the soil. Andosols are inherently highly porous, and biochar application increased soil porosity only at the highest amendment level. The small changes in soil properties and the recalcitrance of the biochar's C components probably account for the unchanged soil-associated greenhouse gas emissions and the minimal impact on crop yield and quality. Because soil CO2 emission was not increased, the net ecosystem C budget during the study period increased with the rate of biochar application from -3.55 +/- 0.19 Mg C ha(-1) without biochar application to 4.89 +/- 0.46, 13.4 +/- 0.3, and 29.9 +/- 0.4 Mg C ha-1 at application rates of 10, 20, and 40 Mg ha(-1), respectively; therefore, application of wood residue-derived biochar to an Andosol has great potential for mitigating global warming through enhanced soil C sequestration without sacrificing crop productivity.
The production of xylooligosaccharides (XOS) by acid hydrolysis using an alkaline extraction filtrate from the bleached kraf t pulp of Eucalyptus globulus is a rapid and effective process. The reaction kinetics knowledge is, however, extremely important to optimize the experimental conditions that maximize XOS production and limit the formation of xylose (unwanted product). In this work, a pseudo-homogeneous model of irreversible first-order reactions is proposed, considering the sequential degradation of fast-reacting xylan into high- and lowmolecular-weight oligomers, followed by their conversion to xylose. A kinetic parameter estimation based on the Arrhenius equation was performed, considering the temperature and acid concentration effects. The kinetic model presented good fittings to the experimental results (R-2 mostly between 0.97 and 0.99), proving its suitability to describe xylan hydrolysis over time. The mapping of XOS maximum yields as a function of pH, temperature, and time was also represented, allowing fast prediction for other operating conditions.
An effective pretreatment is the first step to enhance the digestibility of lignocellulosic biomass - a source of renewable, eco-friendly and energy-dense materials - for biofuel and biochemical productions. This review aims to provide a comprehensive assessment on the advantages and disadvantages of lignocellulosic pretreatment techniques, which have been studied at the lab-, pilot- and full-scale levels. Biological pretreatment is environmentally friendly but time consuming (i.e. 15-40 days). Chemical pretreatment is effective in breaking down lignocellulose and increasing sugar yield (e.g. 4 to 10-fold improvement) but entails chemical cost and expensive reactors. Whereas the combination of physical and chemical (i.e. physicochemical) pretreatment is energy intensive (e.g. energy production can only compensate 80\% of the input energy) despite offering good process efficiency (i.e. > 100\% increase in product yield). Demonstrations of pretreatment techniques (e.g. acid, alkaline, and hydrothermal) in pilot-scale have reported 50-80\% hemicellulose solubilisation and enhanced sugar yields. The feasibility of these pilot and full-scale plants has been supported by government subsidies to encourage biofuel consumption (e.g. tax credits and mandates). Due to the variability in their mechanisms and characteristics, no superior pretreatment has been identified. The main challenge lies in the capability to achieve a positive energy balance and great economic viability with minimal environmental impacts i.e. the energy or product output significantly surpasses the energy and monetary input. Enhancement of the current pretreatment techno-economic efficiency (e.g. higher product yield, chemical recycling, and by-products conversion to increase environmental sustainability) and the integration of pretreatment methods to effectively treat a range of biomass will be the steppingstone for commercial lignocellulosic biorefineries. (C) 2020 Elsevier B.V. All rights reserved.
Conventional food packaging materials are derived from nonrenewable fossil resources and face difficulties in disposal and recycling. The development of green and ecologically balanced food packaging materials has received much attention as a prospective solution that can partially substitute for the imperishable fossil fuel-derived plastic. Polylactic acid (PLA) is known as a promising biopolymer, and the incorporation of nanocellulose can further enhance the properties of this biopolymer. The combination of PLA and nanocellulose enables the development of a sustainable eco-friendly food packaging as PLA can be obtained from agricultural resources and nanocellulose can be extracted from agricultural waste. This critical review demonstrates the current developments, and the advantages of PLA and nanocellulose for the purpose of food packaging are introduced. The nanocellulose produced from agricultural waste is summarized along with specific references to food packaging applications. In addition, the antimicrobial agents used in PLA/nanocellulose-based packaging are discussed. Overall, greener food packaging with enhanced antimicrobial properties with a suitable combination of bio-based nanocellulose is highlighted in this review.
The purpose of this study was to valorize oil palm empty fruit bunch (EFB) and palm fiber (PF) from palm oil mills to produce fuel ethanol. Chemical-free fractionation of EFB and PF using hot-compressed water (HCW) pretreatment at temperatures ranging from 150 to 200 degrees C at 30 bars and reaction times for 5, 15, 25 min was applied to remove most of hemicellulose and partial lignin fractions into liquid phase. Comparison of the effects of different commercial cellulase enzyme complexes (Accellerase 1500, Cellic (R) Ctec2, Cellic (R) Htec2 and Ctec2+Htec2) on HCW pretreated materials were investigated. Finally, an inhibitory effect of using the whole slurry from HCW pretreatment of EFB and PF on enzyme hydrolysis and ethanol production by Saccharomyces cerevisiae TISTR5606 was studied. The finding suggested using solely solid fraction from HCW pretreatment for ethanol fermentation, otherwise some additional tannic acid, furfural and acetic acid removal steps are required to prevent the inhibition on yeast growth. (C) 2019 The Authors. Published by Elsevier Ltd.
The demand for renewable energy is increasing due to increasing energy consumption and global warming associated with increasing use of fossil fuels. Hydrogen gas is considered as a good energy carrier due to its high energy content. Biomass (e.g. agricultural and forestry residues, food industry wastes, and energy crops) is amenable to dark fermentative hydrogen production. However, lignocellulosic materials require pretreatment and/or hydrolysis prior to dark fermentation. This paper reviews potential biomass sources for hydrogen fermentation as well as the effects of different pretreatment and hydrolysis methods on sugar yields as well as hydrogen yields from hydrolyzates. The effects of process parameters on dark fermentative hydrogen production from lignocellulosic hydrolyzates are also discussed. (C) 2014 Elsevier Ltd. All rights reserved.
The aim of this study was to analyze the effect of different extraction solvents in cellulose nanofibers (CNFs) isolation and properties, including nanostructures, chemical functional groups, chemical substances, and thermal stabilities. Physical oven-dried CNFs had a varied diameter of self-aggregated nanofibers from 2 to 20 mu m with different aggregate shapes of nanofibers, whereas individual nanostructure of CNFs suspension was akin to grape-like flocking nanofibers with a diameter of about 50nm. FTIR spectra showed that hot water extraction for CNFs isolation was able to remove low-molecular weight carbohydrates (hemicellulose and pectin), whereas ethanol and ethanol/benzene extraction for CNFs isolation was able to remove tannin, fatty acids, and waxes. However, amorphous lignin was still present indicated with IR transmission peak at 1558 cm(-1). Carboxylic acids, esters, ketones, and benzoyl units were the chemical compounds of CNFs, indicating the presence of cellulose, hemicellulose, and lignin in which long-chain fatty acids were the most dominant compounds. There were five thermal degradation peaks for ethanol- and hot water-pretreated CNFs thermal stability, whereas ethanol/benzene- and non-extraction-pretreated CNFs had four thermal degradation peaks. Solvent-pretreated CNFs had better thermal stability and higher char residue obtained above 8.51\% than that of non-extracted-pretreated CNFs.
The objectives of this study were (1) to produce nanofibrillated cellulose (NFC) from oat hull by employing simple processes based on reactive extrusion combined or not combined with previous bleaching with peracetic acid, with both processes followed by an ultrasonication step; and (2) to characterize the obtained materials according to their composition, morphology, crystallinity and thermal stability. Oat hull was submitted to two different process: (1) extrusion in three sequential steps: first, with NaOH (10\% w/w); then, twice with H2SO4 (2\% w/w); and finally, an ultrasonication step, which resulted in nanofibers with diameters of 100 +/- 25 nm and a yield of 60\%; (2) bleaching with peracetic acid, and then one-step extrusion with H2SO4 (2\% w/w) followed by an ultrasonication step, which resulted in fibers with diameters of 12 +/- 2 nm and a yield of 65\%. Reactive extrusion and the combination of peracetic bleaching with reactive extrusion were effective in the production of NFC from oat hull, and the main advantages from the proposed methods were simplicity and generation of fewer effluents when compared with those of conventional methods that have been described in the literature.
Avocado seed (AS) is an interesting residue for biopackaging because it has high starch content (41 \%). We have prepared composite foam trays based on cassava starch containing different AS concentrations (0, 5, 10 and 15 \% w/w) by thermopressing. Composite foam trays with AS were colorful because this residue contains phenolic compounds. The composite foam trays 10AS and 15AS were thicker (2.1-2.3 mm) and denser (0.8-0.9 g/cm(3)), but less porous (25.6-35.2 \%) than cassava starch foam (Control). High AS concentrations yielded composite foam tray less puncture resistant (similar to 40.4 N) and less flexible (0.7-0.9 \%), but with tensile strength values (2.1 MPa) almost similar to the Control. The composite foam trays were less hydrophilic and more water resistant than control due to the presence of protein, lipid, and fibers and starch with more amylose content in AS. High AS concentration in composite foam tray decreases the temperature of thermal decomposition peak corresponding to starch. At temperatures >320 degrees C the foam trays with AS were more resistant to the thermal degradation due to the presence of fibers in AS. High AS concentrations delayed the degradation time of the composite foam trays by 15 days.
CO2-pressurized liquid hot water was applied to pretreat Sorghum stalk to increase its accessibility for enzyme hydrolysis. Pretreatment temperatures tested ranged from 180 to 220 degrees C, and reaction times varied between 10 and 30 min. The highest total reducing sugar yield of 81.54\% was obtained for the sample pretreated at 200 degrees C and 20 min. Different from the N-2-pressurized liquid hot water process, the generated carbonic acid in the CO2-pressurized method acted as catalyst in the pretreatment process. It was found that the reducing sugar yield increased significantly at lower temperature and shorter reaction time with the addition of CO2. Finally, X-ray diffraction and scanning electron microscope analysis were used to investigate the microstructure of the Sorghum stalk before and after the pretreatment. (c) 2016 American Institute of Chemical Engineers Environ Prog, 36: 208-213, 2017
In the current study, waste marble powder was utilized to produce lightweight fired clay bricks and in the treatment of flue gases. Marble waste powder used in clay bricks and flue gas treatment was collected from local marble processing plants, and its chemical composition was analyzed using energydispersive X-ray analysis and X-ray fluorescence. Clay bricks were produced in local fired clay brick kiln by partial replacement (10-40\%) of clay with calcined and uncalcined waste marble powder. The temperature in the firing zone of the kiln was 1000-1100 degrees C. Clay brick properties such as compressive strength, bulk density, porosity, and water absorption were analyzed. Results show that the porosity of clay bricks increases with an increase in marble waste percentage, and due to an increase in porosity, water absorption of clay bricks also increases, while compressive strength and bulk density decrease. Clay bricks with 10\% uncalcined marble waste and 20\% calcined marble waste satisfy the required Turkish and European compressive strength standard. Marble waste decreases the concentration of sulfur dioxide and particulate matter in flue gases. There is up to 43 and 65\% reduction in the concentration of sulfur dioxide and particulate matters, respectively, in flue gases, after treatment with marble waste. The addition of marble waste to clay bricks is an effective and economical solution for waste marble powder management. Furthermore, it can be used for the treatment of flue gases from brick kilns before its addition to clay bricks.
This study was carried out to evaluate the physico-mechanical and combustion indices of briquettes made from blends of cornhusk (CH) and cassava peel (CP). The CH and CP was torrefied at 200 degrees C to 300 degrees C and were mixed in the ratio 90/10 to 10/90 for briquette production using D-optimal crossed design. The fuel application for co-firing in coal engines was evaluated with fuel ratio, combustibility index and volatile ignitability. The findings revealed that the density, durability index and compressive strength of briquettes blend at 10/90 (CH/CP) torrefied at 300 degrees C and water preconditioned, were respectively improved by 18.19, 2.98, and 32.25\% compared with those for raw briquettes at 10/90 blend ratio. Furthermore, the fixed carbon and calorific value increased with the increase in the torrefaction temperature and time. The produced briquettes at the mixing ratios of 10/90 and 30/70 (CH/CP) torrefied at 300 degrees C for at least 1 hour is sufficient for co-firing in coal engines. The CH and CP wastes with low calorific value which are hitherto discarded could be used to produce briquettes with appropriate qualities attributes of alternative fuel source for heating applications.
Ionic liquids (ILs) pretreatment has emerged as a promising technology toward environmentally benign conversion of lignocellulosic residues into high value cellulosic fiber as sustainable raw material for biocomposite fabrication. This study presents a comparison of ILs-assisted pretreatment of oil palm fronds (OPF) fiber with dilute acid, alkaline, and hot compressed water pretreatments on the mechanical and thermal properties of their fabricated thermo-molded biocomposites with thermoplastic starch as a biopolymer binder. A comparison of energy consumption for ILs pretreatment with other pretreatment methods was also performed and the comparative impact of ILs pretreatment on OPF fiber was investigated by lignocellulosic composition, crystallinity and thermal stability analysis for untreated and all pretreated fibers. Results indicate that ILs pretreatment is superior in terms of delignification of OPF and produces cellulose rich fiber (CRF) with 48-50\% reduced crystallinity as compared to those of acidic, alkaline, and hot water pretreated fibers. However, the flexural strength of the IL {[
Lignocellulosic biomass is one of the potential feedstocks to produce second-generation cellulosic ethanol and biochemicals. To enhance the enzymatic digestibility of lignocellulosic biomass for efficient enzymatic saccharification, a variety of pretreatment methods have been studied. Among these, organosolv pretreatment using ethanol is a promising pretreatment method owing to its inherent advantages, such as low solvent cost, lack of toxicity, the ability to retain most cellulose fraction in substrates for enzymatic hydrolysis, coproduction of high-purity lignin and hemicellulosic sugars, easy solvent recovery, and reuse. In this review, the research progress regarding different types of ethanol organosolv pretreatment processes has been summarized in terms of methods, substrate properties, reaction mechanisms, delignification kinetic as well as the impact of pretreatment methods on the enzymatic digestibility. Attempts are also made to provide insights into the complete utilization of lignocellulosic biomass to achieve high potential revenues. Though some ethanol organosolv processes have been studied or are being developed towards commercialization, ethanol organosolv pretreatment is still facing some challenges. Finally, the direction for future work is given to develop a proper ethanol organosolv pretreatment for commercialization.
The recalcitrance offered by lignocellulose to get converted into simple sugars makes its conversion process complicated, hence pretreatment is required prior to enzymatic hydrolysis and fermentation. Ultrasonication-assisted alkali pretreatment (UA-NaOH) was found to be an effective pretreatment for delignification and enzymatic hydrolysis of denanath grass (DG) and hybrid napier grasses (HNG) in terms of maximum delignification and reducing sugar production. To determine the mechanism of pretreatment and enzymatic hydrolysis, the structural and functional characterization of native and pretreated grass biomass were investigated using SEM (scanning electron microscope), FT-IR (Fourier transformation infrared) spectroscopy, TGA (thermal gravimetric analysis), DSC (differential scanning) spectroscopy, and solid state C-13 CP/MAS NMR (cross-polarization magic angle spinning nuclear magnetic resonance) spectroscopy. The surface erosions, distorted surface morphology and deconstruction of the cell wall components of the Pennisetum sp. were detected by SEM. The differences in the intra- and intermolecular hydrogen bonds that make the crystalline and amorphous regions in the cellulose were detected by FT-IR. While TGA studies revealed higher phenolic content in untreated grass biomass, DSC patterns indicated the formation of laevoglucose in DG pretreated samples. Interestingly, the NMR studies revealed the presence of maximum aliphatic lignin components with absence of the aromatic lignins in both DG and HNG samples. NMR results also showed the presence of maximum hexosans and xylans revealing that the presence of aliphatic lignin components could be a helpful way of retaining the monosaccharides.
A lot of energy is released during the cement manufacturing process, and a large amount of carbon dioxide (CO2) is discharged into the environment. Presently, researchers are focusing on reducing CO2 emissions by researching sustainable alternatives to traditional Portland cement-based materials. A comparative study on the material characterization of both calcined agro-based waste ash (calcined ash) and uncalcined agro-based waste ash (uncalcined ash) and its utilization as a binder along with granulated blast furnace slag (GGBS) in the alkali activation process is carried out in this paper. The study regarding calcined and uncalcined ash would help in better understanding the variation in the properties of the material and its behavior during the alkali activation process. The tests conducted on both calcined and uncalcined ash along with GGBS include specific gravity, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, reaction degree, Brunauer-Emmett-Teller (BET) analysis, particle size distribution, and the Puntke test for understanding its microstructural characteristics. Later, alkali-activated mortars are prepared using 30\% weight of agro-based waste ash (both calcined and uncalcined) and 70\% weight of GGBS. A comparison of the compressive strength of alkali-activated mortars prepared using calcined and uncalcined ash was studied, which showed a promising increase in the strength by 11.02\% of mortar prepared using calcined ash (23.46 MPa) for 28 days when compared to mortar prepared using uncalcined ash (21.13 MPa). The major finding from this study indicates that calcined agro-based ash with GGBS shows better results compared to uncalcined agro-based ash with GGBS.
This study assessed the subcritical water hydrolysis (SWH) of poultry feathers to recover amino acids. Experiments were conducted in a semi-continuous flow-through subcritical reactor (110 mL), which was operated over a range of temperatures (210-250 degrees C) and water flow rates (5-15 mL min-1), combined through a 22 central composite design, at constant feed (10 g) and pressure (15 oa). The results demonstrated that non-essential and essential amino acids were obtained from SWH of poultry feathers. The highest hydrolysis temperature resulted in the highest concentrations of valine, methionine, tryptophan, phenylalanine, isoleucine, leucine, and lysine. Otherwise, threonine, histidine, and arginine were obtained more effectively at lower temperatures. The response surface methodology was adopted to identify the best conditions for amino acid production, and it was possible to identify the ranges of temperatures and water flow rates to be used to recover specific amino acids. This study allowed concluding that SWH is a promising eco-friendly technology to recover amino acids from protein-rich wastes.
The conventional yeast (Saccharomyces cerevisiae) is the most studied yeast and has been used in many important industrial productions, especially in bioethanol production from first generation feedstock (sugar and starchy biomass). However, for reduced cost and to avoid competition with food, second generation bioethanol, which is produced from lignocellulosic feedstock, is now being investigated. Production of second generation bioethanol involves pre-treatment and hydrolysis of lignocellulosic biomass to sugar monomers containing, amongst others, D-glucose and D-xylose. Intrinsically, S. cerevisiae strains lack the ability to ferment pentose sugars and genetic engineering of S. cerevisiae to inculcate the ability to ferment pentose sugars is ongoing to develop recombinant strains with the required stability and robustness for commercial second generation bioethanol production. Furthermore, pre-treatment of these lignocellulosic wastes leads to the release of inhibitory compounds which adversely affect the growth and fermentation by S. cerevisae. S. cerevisiae also lacks the ability to grow at high temperatures which favour Simultaneous Saccharification and Fermentation of substrates to bioethanol. There is, therefore, a need for robust yeast species which can co-ferment hexose and pentose sugars and can tolerate high temperatures and the inhibitory substances produced during pre-treatment and hydrolysis of lignocellulosic materials. Non-conventional yeast strains are potential solutions to these problems due to their abilities to ferment both hexose and pentose sugars, and tolerate high temperature and stress conditions encountered during ethanol production from lignocellulosic hydrolysate. This review highlights the limitations of the conventional yeast species and the potentials of non-conventional yeast strains in commercialization of second generation bioethanol.
Biorefinery is a production system for fuels, energy, and chemicals from biomass in integrated chemical and energy industries, and it provides a new concept to change the petrochemical industry developed in 20th century. There is a growing demand to establish biorefinery to solve the problems of global warming and deficiency of fossil fuels because the biomass feedstock is produced by fixation of carbon dioxide by the photosynthesis of plants. In recent years, research and development for the production of bioethanol and value-added chemicals are progressively expanding, and the U.S. Department of Energy (DOE) selected 12 platform compounds as key intermediates for the biorefinery in USA. In this review, trends in the establishment of platforms for biorefinery and biological pretreatments for the conversion of lignocellulosics using white rot fungi are introduced.
Global demand for renewable and sustainable energy fostered the considerable development of biomass-to-ethanol valorization strategies. Thermochemical pretreatment methods have been proposed to render biomass more amenable to enzymatic and microbial digestion. However, the efforts have not led to its industrial-scale worldwide realization. One of the obstacles to commercialization could be related to water overconsumption, as excessive water washing of the pretreated slurry is often performed to remove inhibitory compounds and residual chemicals after biomass pretreatment. Only increasing solid loading for biomass pretreatment results in ineffective pretreatment performance, more inhibitors formation, and high viscosity, which in turn necessitates the water washing step. A number of physicochemical and biological methods are applied to detoxify the acid-pretreated liquid fraction for enzymatic hydrolysis and fermentation. Among them, alkaline neutralization and liquid-liquid extraction are preferred because of their simple operation and low cost. Seemingly, recycling black liquor for alkali pretreatment offers a pathway to reduce water and chemical consumption, but alkali replenishment and inhibitor accumulation significantly weaken this technology. Interestingly, quite a few studies have removed the water washing and even solid-liquid separation steps after (liquid hot water, Tween 40, and CaO) pretreatment. There is still much room for future studies to render biomass pretreatment more feasible in terms of economic and environmental points of view. This review provides a deep understanding of wastewater generation during biomass upgrading and discusses the solutions to reduce water consumption critically.
Room temperature ionic liquids (RTILs) are emerging as attractive and green solvents for lignocellulosic biomass pretreatment. The unique solvating properties of RTILs foster the disruption of the 3D network structure of lignin, cellulose, and hemicellulose, which allows high yields of fermentable sugars to be produced in subsequent enzymatic hydrolysis. In the current review, we summarize the physicochemical properties of RTILs that make them effective solvents for lignocellulose pretreatment including mechanisms of interaction between lignocellulosic biomass subcomponents and RTILs. We also highlight several recent strategies that exploit RTILs and generate high yields of fermentable sugars suitable for downstream biofuel production, and address new opportunities for use of lignocellulosic components, including lignin. Finally, we address some of the challenges that remain before large-scale use of RTILs may be achieved. Biotechnol. Bioeng. 2011; 108: 1229-1245. (C) 2011 Wiley Periodicals, Inc.
To meet the demand of pulp and paper as well as the environmental legislation the pulp production with eco-friendly approach is desired. This paper presented the state of affairs of Indian and world pulp and paper industry. It also reviewed the discharge of toxic substances from pulp bleaching process and the alternatives for reduction of these toxic substances from pulp bleaching process. The pulp and paper industry is continually changing the bleaching process to minimize the use of chlorine and chlorine based compounds in order to satisfy regulatory and market demands. Imminent to have the minimum impact on environment from bleach plant peracetic acid is the prospective candidate. Use of peracetic acid is a promising technology as it has the capability to reduce/replace chlorine based compounds from pulp bleaching process. This paper reviewed the peracetic acid pulp bleaching and its impact on pulp properties and presented the eco-friendly bleaching process for mixed hardwood. (C) 2020 Elsevier Ltd. All rights reserved.
A systematic literature review was conducted to compare the efficacy of biological, chemical, physical, and combined pretreatments in enhancing biomethane production from crop residues (CR). Three electronic databases viz., Science Direct, EBSCOhost, and PubMed were used to identify the studies in literature. The pretreatment methods were compared in terms of their advantages and disadvantages with reference to techno-economic aspects. The techno-economic aspects considered included rate of hydrolysis, energy use, effectiveness, cost, and formation of toxic compounds. A total of 3167 studies, covering the period 2014 - 2018, were screened for relevance to the study. Forty-four records (n=44) consisting of 36 research papers (n=36) and eight narrative reviews (n=8) met the inclusion criteria. The results show that physical and chemical methods are the most effective and fastest. These methods have limited utility due to high cost of resources, operation, and energy as well as formation of inhibitory by-products. Despite generation of toxic compounds, combined methods are regarded as fast and cost-effective. Biological method is inexpensive, eco-friendly, and low energy-consuming. However, it is a nascent technology that is still developing. A combination of trends in research and development provide the best pretreatment alternative to improve the biomethane production from CR. (C) 2019 BRTeam. All rights reserved.
This paper demonstrates the potential use of the lignocellulosic biomass of pineapple leaves (PALs) as an oil sorbent by mercerization and esterification with long chain fatty acids in order to enhance the surface hydrophobicity and thus the oil sorption capacity for the treatment of dissolved oil contaminated wastewater. The mercerized pineapple leaves (M-PALs) were esterified with lauric acid (LA) and stearic acid (SA) in pyridine-p-toluenesulfonyl chloride (Py-TsCl) solution to yield M-LA-PAL and M-SA-PAL sorbents, respectively, which were then characterized alongside the raw PAL (R-PAL) sorbent using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), CHNS/O analysis and Brunauer-Emmett-Teller (BET) surface area analysis to study the changes of the surface morphology, functional groups, elemental composition and specific surface area of the sorbents. It was found that M-SA-PAL gave the highest sorption capacity (138.89 mg g(-1)) followed by M-LA-PAL (107.67 mg g(-1)) and R-PAL (35.59 mg g(-1)), which are generally lower than dispersed oil sorption capacities. The oil sorption process was found to be exothermic in nature. The data analysis indicated that the sorption process obeyed the Langmuir isotherm and pseudo-second order kinetic models with film diffusion as the rate limiting step, which is similar to some of the reported dispersed oil sorption results. The sorbent regeneration was repeated four times using isopropanol-water (1 : 1, v/v) solution as a desorbing agent and the sorption results were found to be comparable with the freshly prepared sorbent. Finally, the present findings indicate that a lignocellulosic biomass such as PAL could be a potential alternative sorbent precursor for oil removal from oil contaminated wastewaters.
Stabilized blocks have been gaining ground in recent times. Stabilized solid waste blocks provide an eco-friendly alternative to conventional fired bricks. The present investigation dealt with the development of lime stabilized blended solid waste blocks comprising fly ash (FA), steel slag (SS) and phosphogypsum (PG). The PG content was limited to 10\% and the proportion of FA:SS was varied in the remaining 90\% in the ratios of 1:2, 1:1 and 2:1. The blends were stabilized using 2\%, 4\% and 6\% lime. The blends were dry mixed, followed by the addition of a sufficient quantity of water to obtain a uniform wet mix. This mix was then packed into moulds to cast blocks. The blocks were demoulded after 24 hours under wet gunny bags and cured in water for 7 days. Similarly, the blends were also mixed with sand to prepare solid waste mortars blocks and cured for 7 days. At the end of their stipulated curing periods, the stabilized solid waste blocks and mortar blocks were tested for their compressive strength. The results of the investigation revealed that the mix LFSP621 developed the maximum strength of all combinations tested and hence, it can be concluded that the solid waste blend consisting of 60\% FA, 30\% SS and 10\% PG stabilized with a further 6\% lime by weight of the solid waste mix was the most optimal mix for developing maximum strength of the solid waste blocks. The mortar blocks, however, met with limited success. Thus, it can be concluded that stabilized solid waste blocks can become an effective alternative building material.
The fractionation of the aqueous effluent of Aucoumea klaineana Pierre (Okoume) sapwood steam explosion was examined by a sequential-dilution type membrane diafiltration. The permeate and retentate fractions were characterized by HPLC-SEC, HSQC-NMR, FTIR, UV-visible and HPAE-PAD ion chromatography. Diafiltration with 10 kDa regenerated cellulose membrane has been shown to provide efficient fractionation without fouling. O-2 and/or O-3 acetylated xylans with a lower proportion of O2 and/or O-3 acetylated glucomannans were isolated in the retentate (approximate to 35\% w/w and 1.08 w/w\% based on initial effluent solid content and on initial dry wood respectively, including 65\% w/w in the range 9-22 kDa). The molecular weights of the polysaccharides were significantly higher than those obtained by ethanolic precipitation. The permeate concentrated low molecular mass oligomers (90\% w/w < 2.3 kDa, 1.88 w/w\% based on initial dry wood) composed of pectic sugars, highly acetylated xylans (DS approximate to 0.9) and relatively high proportion of soluble lignin (approximate to 40\% w/w) including Lignin-Carbohydrate Complexes (LCCs).
Mixed biomass has the characteristics of stable supply and low cost of collection, and its bio-refinery could provide an effective contribution to the sustainable development of fuel ethanol production. Compared to traditional single energy crops, the key challenge of mixed biomass conversion lies in overcoming the non-uniformity of blended materials. In this study, the influence of blending on hydrolysis and ethanol fermentation of garden wastes was investigated. There was an unexpected result in that the total xylose yield during a liquid hot water process was enhanced when different garden biomasses were mixed. The peak of total xylose recovery appeared at the value of-0.5 for the ratio of xylan to lignin, which was further confirmed by blending multiple biomasses. Moreover, the non-uniformity of physio-chemical characteristics in mixed garden wastes restricted the co-hydrolysis of cellulose, particularly in the mixed-five-biomass. In spite of this disadvantage, blended feedstocks showed a better flow behavior, which could make them more suitable for enzymatic hydrolysis and ethanol fermentation with high substrate loading. The 72 h enzymatic digestibility and glucose concentration of treated mixed three -biomass reached 100 5\% and 52.3 +/- 2.6 g/I under the conditions of 15\% (wilt) substrate loading, with the addition of 1\% (v/v) Tween 20, which gave a maximum ethanol concentration of 16.9 +/- 0.8 g/I. Overall, these results have shown that the complementary or synergistic effects of different individual biomasses make it feasible to produce ethanol from mixed biomass. (C) 2018 Elsevier Ltd. All rights reserved.
To achieve economically competitive biological hydrogen production, it is crucial to consider inexpensive materials such as lignocellulosic substrate residues derived from agroindustrial activities. It is possible to use (1) lignocellulosic materials without any type of pretreatment, (2) lignocellulosic materials after a pretreatment step, and (3) lignocellulosic materials hydrolysates originating from a pretreatment step followed by enzymatic hydrolysis. According to the current literature data on fermentative H-2 production presented in this review, thermophilic conditions produce H-2 in yields approximately 75\% higher than those obtained in mesophilic conditions using untreated lignocellulosic substrates. The average H-2 production from pretreated material is 3.17 +/- 1.79 mmol of H-2/g of substrate, which is approximately 50\% higher compared with the average yield achieved using untreated materials (2.17 +/- 1.84 mmol of H-2/g of substrate). Biological pretreatment affords the highest average yield 4.54 +/- 1.78 mmol of H-2/g of substrate compared with the acid and basic pretreatment average yields of 2.94 +/- 1.85 and 2.41 +/- 1.52 mmol of H-2/g of substrate, respectively. The average H-2 yield from hydrolysates, obtained from a pretreatment step and enzymatic hydrolysis (3.78 +/- 1.92 mmol of H-2/g), was lower compared with the yield of substrates pretreated by biological methods only, demonstrating that it is important to avoid the formation of inhibitors generated by chemical pretreatments. Based on this review, exploring other microorganisms and optimizing the pretreatment and hydrolysis conditions can make the use of lignocellulosic substrates a sustainable way to produce H-2.
The environmental crisis and the need to find renewable fuel alternatives have made production of biofuels an important priority. At the same time, the increasing production of food waste is an important environmental issue. For this reason, production of ethanol from food waste is an interesting approach. Volumes of food waste are reduced and ethanol production does not compete with food production. In this work, we evaluated the possibility of using source-separated household food waste for the production of ethanol. To minimize the cost of ethanol production, the hydrolytic enzymes that are necessary for cellulose hydrolysis were produced in-house using the thermophillic fungus Myceliophthora thermophila. At the initial stage of the study, production of these thermophilic enzymes was studied and optimized, resulting in an activity of 0.28 FPU/mL in the extracellular broth. These enzymes were used to saccharify household food waste at a high dry material consistency of 30\% w/w, followed by fermentation. Ethanol production reached 19.27 g/L with a volumetric productivity of 0.92 g/L center dot h, whereas only 5.98 g/L of ethanol was produced with a volumetric productivity of 0.28 g/L center dot h when no enzymatic saccharification was used.
Production of bio-succinic acid through microbial fermentation using agro-industrial waste has been observed extensively. Large scale production is now being considered since bio-succinic acid has broad range application in several industries including agricultural, food, chemical, metal, and pharmaceutical industry as a precursor, ion chelator, and or additive agent. One of promising microbes able to produce bio-succinic acid in large amount and recognized for industrial production is Actinobacillus succinogenes. However, several factors still need to be considered in order to optimize the fermentation performance. Therefore, this paper aims to review the progress of fermentation methods and discuss the fermentation strategy focused on the influences of different carbon sources, nitrogen sources, pH regulator, and fermentation configuration to the fermentation parameters including concentration, productivity and yield of bio-succinic acid. As a result, combinations of several fermentation strategies are needed to be performed to realize an efficient and effective bio-succinic acid industry. (C) 2019 Published by Elsevier Ltd.
To investigate the ability of the citric acid-producing strain Aspergillus niger ATCC 9142 to utilize the ethanol fermentation co-product corn distillers dried grains with solubles for citric acid production following various treatments. The ability of A. niger ATCC 9142 to produce citric acid and biomass on the grains was examined using an enzyme assay and a gravimetric method, respectively. Fungal citric acid production after 240 h was higher on untreated grains than on autoclaved grains or acid-hydrolysed grains. Fungal biomass production was enhanced after autoclaving and acid-hydrolysis of the grains. Phosphate supplementation to the grains slightly stimulated citric acid production while methanol addition decreased its synthesis. Using the phosphate-supplemented grains, the optimal incubation temperature, initial moisture content of the grains and the length of fermentation time for ATCC 9142 citric acid production were determined to be 25 degrees C, 82\% and 240 h, respectively. A. niger ATCC 9142 synthesized citric acid on corn distillers dried grains with solubles. The phosphate-treated grains increased citric acid production by the strain. The ethanol fermentation co-product corn distillers dried grains with solubles could be useful commercially as a substrate for A. niger citric acid production.
A robust endoxylanase with high activity has great potential in biomass utilization. Here, the catalytic efficiency of the endoxylanase XynF derived from Herbinix hemicellulosilytica was improved by fusing a beta-xylosidase xln-DT derived from Dictyoglomus thermophilum with linkers (L0 and L3) and the direction from xln-DT to XynF. The biochemical properties and application potential of chimeras towards corncob xylan were explored. The result showed that the chimeras Xln-L0-XynF and Xln-L3-XynF exhibited higher catalytic efficiency (31-fold and 20-fold enhancement, respectively), and maintained high stability in some harsh environments compared with parental enzymes. This might be attributed to the appropriate linkers and the direction which decrease the adverse interactions between the two modules. These two chimeras could hydrolyze corncob xylan to produce approximately 30\% xylooligosaccharides with polymerization of 2-6. This work represents the promising xylanases for participating in XOS production from an abundant corncobs and promote us to modify glycoside hydrolase by fusion technology.
Five selected oak sawdust (Quercus sp) pulps (biomass-pt) provided by an ethanosolv pretreatment were dissolved and esterified using the ionic liquid (IL) 1-allyl-3-methyl-imidazolium chloride (AMIM Cl). The AMIM Cl was fully synthesized, purified and used for biomass esterification. The IL synthesis started with a quaternization reaction of 1-methylimidazol with allyl chloride. No reacted materials were removed by vacuum evaporation at 80 degrees C. AMIM Cl was characterized using H-1 and C-13 NMR. Afterward, biomass-pt was dissolved in AMIM Cl and acetic anhydride was added for lignocellulose acetylation. The acetylated material was recovered from the IL using water as anti-solvent. Further purification was made with chloroform. Additionally, for comparison, heterogeneous acetylation of biomass-pt was performed. All the acetylated products were dissolved in dioxane to form films by evaporation-precipitation. The films obtained were characterized microscopically, calorimetrically and by FTIR. From the FTIR and the calorimetric analysis it was concluded that in the heterogeneous acetylation, lignin did not react, and also prevented cellulose from having a high degree of acetylation, greater than commercial cellulose triacetate (TAC). Meanwhile, Lignin was esterified when the pulps were acetylated in AMIM Cl. The analysis by SEM and AFM showed there was a good interaction between acetylated cellulose and acetylated lignin, due to the thickness of the films and the low roughness factor. The AMIM Cl was then the optimal media for biomass acetylation. It could be used as obtained from the synthesis and purification methods proposed.
In this study, the gasification characteristics of four types of unused woody biomass and one waste wood in a lab-scale bubbling fluidized bed gasifier (Diameter: 0.11 m, Height: 0.42 m) were investigated. Effect of equivalence ratio (ER) of 0.15-0.3 and gas velocity of 2.5-5 U-0/U-mf are determined at the constant temperature of 800 degrees C and fuel feeding rate of 1 kg/h. The silica sand particle having an average particle size of 287 pm and olivine with an average particle size of 500 Jim were used as the bed material, respectively. The average product gas composition of samples is as follows; H-2 3-4 vol.\%, CO 15-16 vol.\%, CH4 4 vol.\% and CO2 18-19 vol.\% with a lower heating value (LHV) of 1193-1301 kcal/Nm(3) and higher heating value (HEW) of 1262-1377 kcal/Nm(3). In addition, it was found that olivine reduced most of C2 components and increased H-2 content compared to silica sand, resulting in cracking reaction of tar. The non-condensable tar decreases by 72\% (1.24 -> 0.35 g/Nm(3)) and the condensable tar decreases by 27\% (4.4 -> 3.2 g/Nm(3)).
Purpose: To evaluate the efficacy of the cellulosic exopolysaccharide membrane (CEM) as a urethral reinforcement for urethrovesical anastomosis. Methods: Twenty eight rabbits were submitted to urethrovesical anastomosis with or without CEM reinforcement. The animals were divided into 4 groups: C7, CEM7, C14 and CEM14: (C= only anastomosis or CEM = anastomosis + CEM), evaluated after 7 weeks, and 14 weeks. The biointegration and biocompatibility of CEM were evaluated according to stenosis, fistula, urethral wall thickness, urethral epithelium, rate of inflammation and vascularization. Results: Between the two experimental groups, the difference in the number of stenosis or urinary fistula was not statistically significant. The morphometric analysis revealed preservation of urethral lumen, well adhered CEM without extrusion, a controlled inflammatory process and implant vascularization. The urothelium height remained constant over time after CEM reinforcement and the membrane wall was thicker, statistically, after 14 weeks. Conclusion: The absence of extrusion, stenosis or urinary fistula after 14 weeks of urethrovesical anastomosis demonstrates cellulosic exopolysaccharide membrane biocompatibility and biointegration with tendency to a thicker wall.
In the present study, novel pre-treatment for spent coffee waste (SCW) has been proposed which utilises the superior oxidising capacity of alkaline KMnO4 assisted by ultra-sonication. The pre-treatment was conducted for different exposure times (10, 20, 30 and 40 min) using different concentrations of KMnO4 (1, 2, 3, 4, 5\% w/v) at room temperature with solid/liquid ratio of 1:10. Pretreating SCW with 4\% KMnO4 and exposing it to ultrasound for 20 min resulted in 98\% cellulose recovery and a maximum lignin removal of 46\%. 1.7 fold increase in reducing sugar yield was obtained after enzymatic hydrolysis of KMnO4 pretreated SCW as compared to raw. SEM, XRD and FTIR analysis of the pretreated SCW revealed the various effects of pretreatment. Thermal behaviour of the pretreated substrate against the native biomass was also studied using DSC. Ultrasound-assisted potassium permanganate oxidation was found to be an effective pretreatment for SCW, and can be a used as a potential feedstock pretreatment strategy for bioethanol production. (C) 2016 Elsevier Ltd. All rights reserved.
The aim of this study was to evaluate the fertility status, milk output, mortality, and body thermoregulation of rabbit does as affected by different levels of multi-enzyme extracts (EZ) in their diets. A total of 120 Hy-Plus rabbit does were divided into four comparable experimental groups (n = 30 does per group). Animals of each group were divided in six pens (five animals per pen), and each pen was used as an experimental unit. The first group was kept untreated and fed a commercial diet alone without enzyme extracts (EZ0), while the other groups were fed the same diet but supplemented with 1 (EZ1), 3 (EZ3), and 5 (EZ5) kg/ton of enzyme extracts, respectively. Feeding EZ additive increased (P < 0.05) conception and kindling rates, litter size and weight at birth, and litter size and bunny weight at weaning, with decreasing (P < 0.05) abortion rate. Moreover, total milk yield increased (P < 0.05) with increasing level of enzyme supplementation. Pre-weaning mortality decreased (P < 0.05) with EZ inclusion. Signs of vitality (rectal temperature, skin temperature, earlobe temperature, respiration rate, and pulse rate) were improved with EZ inclusion. For all results, 5 kg EZ/ton of feed was more effective than 1 and 3 kg EZ/ton feed. It can be concluded that supplementation of EZ in rabbit diet decreased mortality rate and enhanced fertility status and milk output.
The goal of this study was to evaluate the use of expanded clay as a support material for Thermoanaerobacterium thermosaccharolyticum KKU19 to produce hydrogen from oil palm trunk hydrolysate (OPT) and slaughterhouse wastewater (SHW) in a fixed-bed reactor (FBR) under non-sterile conditions. The effects of hydraulic retention time (HRT) on the performance of the FBR were also investigated. The FBR was operated at an OPT hydrolysate to SHW ratio of 2.55:1 (v:v), 60 degrees C, initial pH 6.5, and 1.2 mg (as total volatile solids/g expanded clay) of T. thermosaccharolyticum KKU19 immobilized on expanded clay. A maximum hydrogen production rate (HPR) and hydrogen yield (HY) of 7.15 +/- 0.22 L/L day and 234.45 +/- 5.14 mL H-2/g-COD, respectively, were obtained at an HRT of 6 h. Long-term operation of FBR at 6 h HRT indicated that expanded clay efficiently immobilizes T. thermosaccharolyticum KKU19, for which an HPR of 6.82 +/- 0.56 L H-2/L day, and an HY of 231.99 +/- 19.59 mL H-2/g-COD were obtained. Furthermore, the COD removal efficiency of 30\% obtained under long-term operation was comparable to that under short-term operation at an HRT of 6 days. Butyric and acetic acids were the main soluble metabolite products, thereby indicating a butyrate-acetate type fermentation. Our findings indicate that expanded clay is an effective support material that contributes to the protection of microbial cells and can be used for long-term operation.
Background: Trichoderma harzianum is used in biotechnology applications due to its ability to produce powerful enzymes for the conversion of lignocellulosic substrates into soluble sugars. Active enzymes involved in carbohydrate metabolism are defined as carbohydrate-active enzymes (CAZymes), and the most abundant family in the CAZy database is the glycoside hydrolases. The enzymes of this family play a fundamental role in the decomposition of plant biomass. Results: In this study, the CAZymes of T. harzianum were identified and classified using bioinformatic approaches after which the expression profiles of all annotated CAZymes were assessed via RNA-Seq, and a phylogenetic analysis was performed. A total of 430 CAZymes (3.7\% of the total proteins for this organism) were annotated in T. harzianum, including 259 glycoside hydrolases (GHs), 101 glycosyl transferases (GTs), 6 polysaccharide lyases (PLs), 22 carbohydrate esterases (CEs), 42 auxiliary activities (AAs) and 46 carbohydrate-binding modules (CBMs). Among the identified T. harzianum CAZymes, 47\% were predicted to harbor a signal peptide sequence and were therefore classified as secreted proteins. The GH families were the CAZyme class with the greatest number of expressed genes, including GH18 (23 genes), GH3 (17 genes), GH16 (16 genes), GH2 (13 genes) and GH5 (12 genes). A phylogenetic analysis of the proteins in the AA9/GH61, CE5 and GH55 families showed high functional variation among the proteins. Conclusions: Identifying the main proteins used by T. harzianum for biomass degradation can ensure new advances in the biofuel production field. Herein, we annotated and characterized the expression levels of all of the CAZymes from T. harzianum, which may contribute to future studies focusing on the functional and structural characterization of the identified proteins.
Cellulose and lignin nanoparticles are high-value-added products obtained from lignocellulosic biomasses through several steps of cellulose purification and lignin extraction. These steps drastically reduce the potential feedstock revenue when carried out as stand-alone methodologies. To increase biomass yields, we describe here a strategy to design a biorefinery focused on producing cellulose and lignin nanoparticles as main products, but also aim to recover and benefit from other biomass components using only water-based processes. Sequential pressurized liquid extractions and diluted acid and alkaline treatments were carried out to fractionate elephant grass biomass, yielding (for every 100 g of biomass): 30 g of cellulose pulp (converted to 9 g of cellulose nanocrystals and 9 g of cellulose nanofibers); 10 g of lignin (used to produce 8.5 g of stable colloidal lignin nanoparticles by probe-sonication in water); 7.5 g of extractives (e.g. sterols and phenolics) and 23 g of xylose (converted to 4.1 g of furfural). Alternatively, to allow for the flexible use of the cellulose fraction in the proposed biorefinery, 22 g of glucose could be produced by enzymatic hydrolysis. The results demonstrate that water-based processes are suitable for a holistic use of biomass, providing a comprehensive set of high-value-added co-products that are renewable and cost-effective chemical, cosmetic, food, polymer and pharmaceutical solutions.
This work evaluated the effect of cationic surfactants {[
Oil palm industry contributes a huge amount of valuable crude palm oil, and simultaneously producing a large quantity of plantation waste or biomass, which will be utilized as fuel. In order to give a clear insight of the energy output estimation from the biomass, a comprehensive study on the physical properties of the biomass: bulk density and moisture content is crucial. In a conventional approach, these properties are obtained through empirical methods on individual sample basis. However, the conventional empirical methods have several drawbacks: (i) require a huge amount of experimental results to construct biomass properties' curve (ii) data variation affects the accuracy of analysis result. These create a limitation in properties estimation and further affecting the optimum biomass utilization. To tackle this issue, there is a need to search for a direct representation of the properties. A Biomass Characteristics Index (BCI) is proposed to represent the relationship between bulk density and moisture content. A numerical framework is developed to determine the BCI. This index is used to estimate the biomass bulk density and moisture content before the calorific value calculation. A regression graph is plotted to illustrate the relationship among those values with respect to different appearance shapes of biomass. The result shows that different size and shape of biomass has its own specific BCI. The classification of biomass according to its specific BCI can forecast the related bulk density and moisture content. Therefore, it reduces the hassle, especially in terms of time constraint to get those values through conventional empirical method. This will increase the overall biomass operational management efficiency. (C) 2016 Elsevier Ltd. All rights reserved.
Oat hull hemicellulosic hydrolysate obtained by diluted acid hydrolysis was employed as fermentation medium for Pichia stipitis cultivation. A comparison between the use of treated hydrolysate with 1\% activated charcoal to reduce the toxic compounds generated during the hydrolysis process and untreated hydrolysate as a control was conducted. In the cultures using treated hydrolysate the total consumption of glucose, low xylose consumption and ethanol and glycerol formation were observed. The medium formulated with untreated hydrolysate showed morphological cell modifications with consequently cell death, no ethanol formation and formation of glycerol as byproduct of fermentative process, probably as a response to stressful conditions to yeast due to presence of high concentration of toxic compounds. Thus, further studies are suggested in order to determine the best conditions for hydrolysis and detoxification of the hydrolysate to improve the fermentative performance of P. stipitis.
The pyrolysis behaviour of two different beet pulps was studied in a fluidized bed reactor. Cellulose beads were pyrolyzed as a reference material. Four reaction temperatures, ranging from 673 to 823 K were studied. The distribution of product phases and the composition of the bio-oils were affected by the different raw materials. (C) 2013 Elsevier B.V. All rights reserved.
The experiment was carried out to evaluate addition effects of five urea levels with four ammonization periods on Agave sisalana residue chemical composition in the different storage times. It was used 300 kg of this co-product, equally distributed in 60 black polyethylene bags, which urea was added in the following concentrations: 0, 2, 4, 6 and, 8\% over 0, 2, 4 and, 6 weeks storage periods. It was made determinations of dry matter (DM), crude protein (PB), neutral detergent fiber (NDF), acid detergent fiber (ADF) and, non fibrous carbohydrates (NFC). A completely randomized design was adopted, following factorial arrangement 5 x 4 (urea levels, ammonization periods), with three replications. The variance analyses showed significant effect of urea level on variables CP and DM. For ADF and NFC there were significant effects for the interaction level versus period of fermentation; for NDF variable it was not possible to adjust a statistical model. The CP rates grew linearly with the urea addition. Ammonization did not affect NDF rates. Crude protein level had a linear increase by urea addition. Besides, it was noticed that ADF rate increased in function of NFC decreasing. NFC rate reduced as a consequence of urea level increase, showing that it was likely used for microbial synthesis or carried with the effluent. It was concluded that the addition up to 8\% of urea increased the CP content and reduced the NFC and DMD contents with the increase in the storage time.
Reasonable porous structure and proper heteroatom doping have great influences on electrode materials for supercapacitors. Herein, O, N, and P codoped hierarchical porous carbon (ONPC) was synthesized through a one-pot carbonization-activation strategy by using chitosan as the carbon precursor, phosphoric acid as the activator, and melamine foam as the skeleton. The use of melamine foam facilitated the formation of an interconnected carbon framework and introduced more nitrogen functional groups. Owing to the hierarchical pore structure, large surface area (1588 m(2) g(-1)), and significant heteroatom contents of O (8.61\%), N (7.95\%), and P (1.34\%) in the carbon matrix, the 700 degrees C carbonized sample ONPC700 had a specific capacitance of 230 F g(-1) at 0.2 A g(-1). A high energy density of 7.5 Wh kg(-1) at 100 W kg(-1) was achieved for the supercapacitor fabricated with two identical ONPC-700 electrodes. Furthermore, the capacitance retention of the device was evaluated to be as high as 86.53\% after 8000 cycles.
In this study, the behavior of lead (Pb2+), chromium (Cr3+), and copper (Cu2+) ions in several aqueous solutions during biosorption of peach palm sheath colonized with Agaricus blazei (PS+A. blazei) was evaluated. The modifications of the chemical structure of the biosorbent due to fungal growth were verified by scanning electronic microscopy (SEM) which showed the differences on the material surface. Biosorption of Pb2+ and Cr3+ was dependent of solution pH. Although in natura peach palm sheath and peach palm sheath with A. blazei growth have shown different behaviors in pH evaluations for the three metals, it was chosen to use pH 5.0 in all the other experiments due to the high biosorption values for all metal/biosorbent relations when compared to other pH values. The reaction reached equilibrium in 15min and the pseudo-second-order model presented the best results for all metal/biosorbent interactions. The data for q(max) showed that for all metals PS+A. blazei was better to retain ions when compared to in natura peach palm (PS). Peach palm sheath colonized with A. blazei presented the highest biosorption capacity when interacting with Pb2+ ion (53mgg(-1)). Biosorption isotherms were tested for the mathematical models of Langmuir, Freundlich, Dubinin-Radushkevichs and Temkin, and all of them were adequate for the equilibrium experimental data. The differences of sorption affinity are directly linked to electronegativity difference which also follows this order: Pb2+>Cu2+>Cr3+. Through thermodynamic parameters, it was verified that biosorption processes are spontaneous and exothermal.
Bio-energy from lignocellulosic biomass is cleaner, sustainable, and one of the renewable energy sources that could help meet some of our energy demand. Unlike fossil fuels, it can be grown and used repeatedly and its use can replace the fossil fuels. In addition to this, these materials are easily available either in the form of agricultural waste or forest residues and are economically viable. The current study focuses on physico-chemical characterisation of three commonly available lignocellulosic biomasses of north-east India such as Castor (Ricinus communis), Jatropha (Jatropha curcas), and Miscanthus (Miscanthus sinensis) for second generation biofuels production. Ultimate analysis (CHNSO), thermogravimetric analysis, X-ray diffraction, Fourier transformation infrared (FTIR), and oxygen bomb calorimeter techniques were used to characterise the above mentioned three lignocellulose biomasses. It was found that the cellulose content of three biomasses varied from 40\% to 44\%, hemicellulose content from 8\% to 14\%, and lignin content varied from 21\% to 30\%. Chemical structure of lignocellulose is studied through FTIR. The crystallinity index of Castor and Jatropha is similar, i.e., similar to 69\%, where as crystallinity index of Miscanthus was 72\%. Due to the presence of higher carbon and cellulose content along with less moisture (10\%-12\%), ash (5\%-10\%), sulphur (0.1\%-0.8\%), and extractives (12\%-20\%) make them a very good source for production of alcoholic fuels through a biochemical route. (C) 2015 AIP Publishing LLC.
Costly and non-environment-friendly methods are used to improve the inferior behavior of recycled aggregate concrete (RAC). Conversely, the strength enrichment of concrete due to confinement provided by lateral reinforcement is ignored in the design of concrete compression members. The focus of this study is to investigate the role of pre-existing transverse reinforcement and different design strengths of concrete on the stress strain behavior of RAC. For this reason, stress-strain behavior of spiral steel confined concrete specimens having variable confinement pressure, recycled aggregates (RA) replacement percentage and design strength is investigated. The results show a drop in compressive strength of concrete with the increase in replacement percentage of RA. However, steel confinement has a positive role to counterbalance the adverse effect of RA replacement on concrete strength. Improved ductility and stress-strain behavior of RAC are observed with the increase in confinement pressure. Based on the results, the un-utilized pre-existing steel spiral reinforcement in the concrete compression members can offset the inferior performance of RAC resulting into sustainable and cost-effective construction.
Ultrafiltration and nanofiltration of spent sulphite liquor ( SSL) has been employed to evaluate the simultaneous production of lignosulphonates and bio-based succinic acid using the bacterial strainsActinobacillus succinogenes and Basfia succiniciproducens. Ultrafiltration with membranes of 10, 5 and 3 kDa molecular weight cut-off results in significant losses of lignosulphonates (26-50\%) in the permeate stream, while nanofiltration using membrane with 500 Da molecular weight cut-off results in high retention yields of lignosulphonates (95.6\%) in the retentate stream. Fed -batch bioreactor cultures using permeates from ultrafiltrated SSL resulted in similar succinic acid concentration (27.5 g/L) and productivity (0.4 g/L/h) by both strains. When permeates from nanofiltrated SSL were used, the strain B. succiniciproducens showed the highest succinic acid concentration (33.8 g/L), yield (0.58g per g of consumed sugars) and productivity (0.48 g/L/h). The nanofiltration of 1 t of thick spent sulphite liquor could lead to the production of 306.3 kg of lignosulphonates and 52.7 kg of succinic acid, whereas the ultrafiltration of 1 t of thick spent sulphite liquor using a 3 kDa membrane could result in the production of 237 kg of lignosulphonates and 71.8 kg of succinic acid when B. succiniproducens is used in both cases. (C) 2016 Elsevier B.V. All rights reserved.
Viscose fiber mills generate a lot of wastewater enriched with hemicelluloses. The structure of the hemicellulose in the wastewater was characterized and the hemicellulose was isolated to produce xylooligosaccharides (XOS). It was confirmed that the hemicellulose was mainly 4-0-methylglucuronoxylan with a small amount of glucomannan and xyloglucan. The 4-0-methylglucuronoxylan was completely de-acetylated and linear with a few 4-0-methyl glucuronic acid attached. After purified by the acid precipitation and washing, the hemicellulose was pretreated by dilute acid, and then subjected to xylanase hydrolysis. After the dilute H2SO4 pretreatment at pH 2.6 and 150 degrees C for 30 min and the followed xylanase hydrolysis (65 IU/g xylan), the total XOS yield was improved from 0.215 to 0.578 g/g xylan. The percentage of XOS in the final sugar product was 68.9\%. These results demonstrated the potential economical and environmental benefits of the process to utilize the byproducts from viscose fiber mills. (C) 2016 Elsevier Ltd. All rights reserved.
Enhancing energy cane biomass production can increase feedstock supply for lignocellulosic-based ethanol production. This study was conducted at the Louisiana State University Agricultural Center (LSU AgCenter) Sugar Research Station in St. Gabriel, LA, from 2013 to 2015 to evaluate yield, fiber composition, and nutrient removal rate of energy cane harvested at different dates. The treatments included two energy cane cultivars ('Ho 02-113' and `Ho 72-114') and four N rates (0, 56, 112, and 224 kg N ha(-1)), arranged in split plot in a randomized complete block design with four replications. Fifteen plants were collected once a month beginning 2 mo prior to the harvest date and then separated into leaves and stalks and analyzed for fiber and nutrient composition. Harvest date, cultivar, and N rate significantly affected energy cane yield (stalk and leaves), quality components, lignocellulosic composition, and nutrient removal rate (p < .05). On average, harvesting energy cane 1 and 2 mo earlier than the scheduled harvest date reduced stalk yield by 4\% and 20\% and leaf yield by 3\% and 15\%. Minimal changes on stalk fiber content and lignocellulosic composition in response to the treatments were documented but no specific and consistent trend was established. With leaf included, energy cane biomass production was increased by 32\%; however, this can result in significant removal of plant essential nutrients, particularly N (105 kg ha(-1)), P (16 kg ha(-1)), and K (116 kg ha(-1)). The long-term impact of complete removal of energy cane biomass from the field could result in decline in soil fertility and productivity.
A life cycle assessment (LCA) study was carried out to evaluate the environmental implications of the production and use of ethanol from three fast-growing wood crops: eucalyptus, black locust and poplar in flexi-fuel vehicles. The production of a blend rich in ethanol: E85 (85\% ethanol and 15\% gasoline by volume) was assessed and the results compared with those of conventional gasoline (CG) in an equivalent car. The following environmental categories were evaluated: fossil fuels use (FF), global warming potential over 100 years (GWP(100)), photochemical oxidant creation potential (POCP), acidification potential (AP) and eutrophication potential (EP). The use of ethanol derived from black locust was found to be the option with the lowest impact in most categories with reductions of 97\%, 42\%, 41\% and 76\% for GWP(100), AP, EP and FF respectively in comparison with CG.44 Concerning the production stage of ethanol (excluding the stages of blending and use), black locust has the lowest environmental impacts due to the low levels of agricultural inputs during its cultivation. The poplar scenario has higher impacts in AP and EP due to the emission of diffuse substances from fertilizer application and the eucalyptus scenario in GWP(100), POCP and FF due to the use and requirements of heavy machinery during harvesting. The use of the LCA methodology has helped to identify the key areas in the life cycle of ethanol. Special attention should be paid to ethanol production related activities and forest activities oriented to the feedstock production. (C) 2012 Elsevier Ltd. All rights reserved.
Banana cultivation is a generator of large amounts of lignocellulosic residues. In Brazil, the fifth largest banana producer in the world, most of these residues are abandoned in plantations, being means of proliferation of vectors and sources of gases harmful to the environment. The cellulose extraction is an important alternative to allocate higher added value to these residues, promoting their reuse. The cellulose extraction process involves the removal of amorphous materials from lignocellulosic materials, especially the lignin. Thus, this study proposed to identify cellulose extraction processes, aiming to assist in the advancement of scientific research and projects that promote the use of cellulose present in these residues. For this purpose, a bibliometric research was conducted in the Science Direct and Springer databases. In the analysis of the material it was identified that the process used for the fragmentation of hemicellulose and lignin is hydrolysis (alkaline, acidic and enzymatic), under controlled conditions.
This study focuses on the removal of Mn(II) ions from aqueous solution using esterified saw dust. Most studies report single metal solutions; however, in practice the presence of only a single component in waste waters is highly unlikely. Keeping this in view, binary metal adsorption studies have been undertaken to investigate the effect of Fe(II) on the removal of Mn(II). Succinic anhydride has been used for the esterification of saw dust which has been characterised using proximate and Fourier transform infrared spectroscopy analyses. The effect of parameters such as metal ion concentration, time, pH, particle size of adsorbent and temperature on adsorption has been studied. Results obtained at optimum conditions (concentration 300 mg/L, pH 5 and time 150 min) have been subjected to isotherm analyses which show that adsorption is monolayer and physical in nature. Kinetic studies reveal that the process follows first-order kinetics, and intra-particle diffusion also occurs but it is not the rate-determining step. Thermodynamic studies indicate the adsorption process to be endothermic and spontaneous in nature. The Langmuir competitive model was applied to binary sorption to analyse the nature of competition among Mn-Fe ions, which shows that the adsorption of Mn(II) was supressed by the presence of Fe(II) ions.
This study was conducted to evaluate the importance of aeration in free and immobilized cell systems in an aerated bioreactor for xylitol production from an oat hull hemicellulosic hydrolysate using an integrated process. The aeration rate (AR) or oxygen mass transfer coefficient (k(L)a) demonstrated a significant role in controlling cell (Candida guilliermondii FTI 20037) regeneration and bioconversion performance in free and immobilized cell systems. In the free cell system, an aeration rate of 1.25 vvm corresponding to k(L)a of 15.81/h resulted in maximum values of product yield (Y-p/s: 0.87 g/g), productivity (Q(p): 0.57 g/l/h), and final xylitol concentration (P-f: 55 g/l) from the hydrolysate with a 74.5 g/l xylose concentration. However, in the aerated immobilized cell system, maximum and almost similar results (almost P-f: 54 g/l, Q(p): 0.57 g/l/h and Y-p/s: 0.84 g/g) were obtained with aeration rates from 1.25 to 1.5 vvm using composites based on polypropylene (PP) and partially delignified fiber (PDF). Composites based on acid treated fiber (ATF) containing a high amount of lignin showed some inhibitory impact on xylose uptake and xylitol formation (P-f: 47 g/l and Q(p) <0.49 g/l/h) with the optimal aeration rate of 1.5 vvm in the initial cycle of the bioconversion; this inhibition impact could be resolved in the next consecutive cycles. The surface modifier polyethyleneimine (PEI) slightly enhanced cell retention in the immobilized form on the ATF-based cell support. This investigation helps fill in the knowledge gaps existing on the integrated processing of the lignocellulosic biomass for xylitol bioproduction and biorefinery industry; however, more scale-up studies are recommended for commercialization. (C) 2013 Elsevier B.V. All rights reserved.
The study investigated the feasibility of co-production of nanocellulose crystal (CNC) and ethanol using the bleached pine kraft pulp (BPKP) as a substrate by enzymatic hydrolysis. An engineering strain Penicillum oxalicum cEES-XM was constructed to produce suitable cellulase used in enzymatic hydrolysis of BPKP for preparing CNC. The cellulase from Trichoderma reesei SCB18 was used for simultaneous saccharification and fermentation of residues and hydrolysates from enzymatic hydrolysis for producing ethanol. The result showed that the CNC yield reached 7.35 \% (w/w) by hydrolysis at 10 \% solid content, and the final ethanol concentration was 13.27 mg/mL in fermentation liquor. Using SEM, XRD, TGA, and DLS methods, the characteristics of CNC including, morphology, crystallinity, thermal stability and particle size distribution, were also examined. This work provided a reference for realizing high-efficient application of cellulose in the pulp.
Despite its pozzolan properties, a great percentage of rice husk ash (RHA) is disposed as waste, thus generating adverse environmental impacts. This study was intended to assess compressive strength and absorption in soil-cement block when including RHA as a substitute for Portland cement (PC). This methodology consisted on preparing three mixtures of soil-cement including different RHA percentages as a substitute for PC: M1 (10\% PC + 0\% RHA), M2 (7.5\% PC + 2.5\% RHA) and M3 (5\% PC + 5\% RHA). Results show that compressive strength decreases 12.64\% and 26.78\% in M2 and M3, respectively. Regarding water absorption, it increases when adding RHA. M2 reported the best results for analyzed properties. However, for both properties, values are present within ranges recommended to be used in construction sector based on Brazilian and Bolivian codes, NBR 10834 and NB 1211003, respectively. Using RHA is viable in order to produce soil-cement blocks as a substitute for PC; however, further tests (e.g. durability, flexural strength, tensile strength, etc.) -in order to determine optimal replacement percentages for quality assurance in produced material- are required. (C) 2021 The Author(s). Published by Elsevier Ltd.
An ultrasound-assisted procedure was applied to the extraction of hemicelluloses from grape pomace at a mild temperature (20 degrees C). A Central composite design (CCD) was employed to optimize the ultrasound-assisted extraction (UAE) of hemicelluloses from grape pomace with the aim to maximize their extraction yield, and, also, the obtention of the main polymers forming this fraction: Xyloglucans (XLG), Mannans (MAN) and Xylans (XN). Extraction time (X-1), solid:liquid ratio (X-2) and KOH concentration (X-3) were the variables used to optimize the process. The conditions that maximize (1) the extraction yield of hemicelluloses and the contents of (2) XLG, (3) MAN and (4) XN, were: (1) X-1 = 2.6h; X-2 = 1:48 (W/V); X-3 = 0.4M, (2) X-1 = 2.9h; X-2 = 1 :57 (W/V); X-3 = 2.25M, (3)X-1 = 2.7h; X-2 = 1 :58(W/V);X-3 = 2.2M, and (4)X-1 = 3h; X-2 = 1:60 (w/v); X-3 = 2.3M, respectively. Under these conditions, the maximum extraction yield of hemicelluloses, XLG, MAN and XN contents were: similar to 7.9 +/- 0.2\%, similar to 3.6 +/- 0.02\%, similar to 1.1 +/- 0.04\% and similar to 1.2 +/- 0.02\%, respectively. Close agreement between experimental and predicted values was found. The results suggest that the ultrasound-assisted extraction could be a good option for the extraction of hemicellulosic polysaccharides from grape pomace at industrial level. (C) 2015 Elsevier Ltd. All rights reserved.
In the recent past, renewable biobased natural polymers have been explored for their variety of potential applications. Among the various biorenewable polymers, cellulose with ingrained robust characteristics such as biodegradability, nontoxicity, durability, availability, thermal and mechanical stability etc., is extensively studied. These properties can further be improved by different modification techniques, among which the grafting is considered to be the most influencive one. In this comprehensive review article, the general chemistry of the cellulose, different biological, chemical, physical, physio-chemical extraction techniques for its extraction from lignocellulosic biomass, purification and bleaching techniques for extracted cellulose, methods of cellulose grafting, mechanism of free radical grafting initiated by a variety of chemical initiators, are reviewed. Further, recent developments in the field of metal ion sorption applications of grafted cellulosic copolymers, related factors affecting the metal ion sorption efficiencies of these cellulosic biosorbents such as extent of grafting, contact time, temperature, pH, interference of other metal ions, metal ion concentration, biosorbent dose, ionic strength of solution etc. are also reviewed. Various adsorption isotherms models-Langmuir, Freundlich, Temkin, Dubinin-Raduskevich and Redlich-Peterson; adsorption kinetic models-pseudo-first-order, pseudo-second-order, and intra-particle-diffusion models, useful for studying and evaluating the different sorption parameters, mechanism, and rate of sorption of toxic and hazardous heavy metal ions, are also summarized. In the last part of the review, adsorption thermodynamics, desorption and regeneration studies for the grafted cellulosic biosorbents are also reviewed. (C) 2017 Elsevier B.V. All rights reserved.
Ligninis a highly abundant biopolymer with a complex polyphenolicstructure, making it a potential source of aromatic precursors, polymers,and energy. However, its thermal stability limits its economic potential,with less than 3 wt \% of waste lignin transformed into commodityproducts. This review focuses on the chemical and biological extractionmethods for lignin to promote its valorization, which involves extraction,depolymerization, and fermentation or derivatization. As there isno universal method for extraction due to the heterogeneity of lignin,a range of methods each with their advantages and disadvantages arediscussed, including sulfite pulping, Kraft, Organosolv, ozonolysis,steam-explosion, ionic-liquids and supercritical CO2 extraction,and microwave- and ultrasound-assisted extraction. Biological methods,such as bacterial, fungal, and enzymatic delignification, are alsoexplored. The review aims to provide insights to tailor extractionmethods to individual needs and promote the sustainable utilizationof lignocellulosic biomass.
In this paper the authors provide comparative evaluation of current research that used liquefaction and pyrolysis method for bio-oil production from various types of biomass. This paper review the resources of biomass, composition of biomass, properties of bio-oil from various biomass and also the utilizations of bio-oil in industry. The primary objective of this review article is to gather all recent data about production of bio-oil by using liquefaction and pyrolysis method and their yield and properties from different types of biomass from previous research. Shortage of fossil fuels as well as environmental concern has encouraged governments to focus on renewable energy resources. Biomass is regarded as an alternative to replace fossil fuels. There are several thermo-chemical conversion processes used to transform biomass into useful products, however in this review article the focus has been made on liquefaction and pyrolysis method because the liquid obtained which is known as bio-oil is the main interest in this review article. Bio-oil contains hundreds of chemical compound mainly phenol groups which make it suitable to be used as a replacement for fossil fuels.
As a derivative of agriculture crops and forestry cultivated plants, cellulosic fiber product (CFP) is of much industrial interest deemed a promising alternative to wooden composites and plastics owing to the low environmental impact. The high-performance CFP was fabricated via a facile molding and hot-pressing process without using adhesives. The UV aging test was carried out to evaluate the physical and mechanical stability before and after delignification. The tensile strength was increased from 41.3 MPa to 53.7 MPa, and the flexural strength was increased from 72.3 MPa to 85.4 MPa as the lignin was removed from 11.7\% to 3.0\%. The holocellulose content and crystallinity of fibers were increased, and the fiber dimensions were correspondingly decreased after delignification. However, the delignified specimens exhibited a faster reduction in mechanical strength than that of lignin-rich products (e.g., 0.074 vs 0.041 in the slope rate of fitting curves) throughout the UV irradiation, and the thermal stability was also decreased from 317.2 \& DEG;C to 311.3 \& DEG;C in onset decomposition temperature due to the delignification. Moreover, the lignin-rich CFP was superior to that of typical plastics (e.g., PP and epoxy resin) and wooden composites (e.g., WF/PP) in mechanical and thermal stability under UV irradiation through the comparison.
Recent techno-economic studies of proposed lignocellulosic biorefineries have concluded that creating value from lignin will assist realization of biomass utilization into valuable fuels, chemicals, and materials due to co-valorization and the new revenues beyond carbohydrates. The pretreatment step within a biorefinery process is essential for recovering carbohydrates, but different techniques and intensities have a variety of effects on lignin. Acidic and alkaline pretreatments have been shown to produce diverse lignins based on delignification chemistry. The valorization potential of pretreated lignin is affected by its chemical structure, which is known to degrade, including inter lignin condensation under high-severity pretreatment. Co-valorization of lignin and carbohydrates will require dampening of pretreatment intensities to avoid such effects, in spite of tradeoffs in carbohydrate production.
Every year the agricultural product processing industries produce large quantities of agricultural waste biomass (AWB). Whose disposal has become a serious issue concerning solid waste management due to environmental and health issues. Microwave-assisted pyrolysis (MAP) is an intriguing technology for producing valuable products from waste feedstocks. AWB is converted into a valuable product like biochar by using MAP. The conversion of AWB into biochar by MAP is influenced by several factors such as type of feedstock, pyrolysis temperature, residence time, pressure, heating rate, susceptor, particle size, and microwave power. However, no review article is available to understand the role of MAP on biochar production from AWB. The current review focused on understanding the fundamentals of biochar production. It also reviews the challenges in producing biochar process by compatible, acceptable, and sustainable and its future directions to gain economic benefits even at small-scale applications. The generation of biochar from MAP and its uses in agriculture are discussed. The current review would address the knowledge gap and highlight the critical implications in biochar pro-duction and applications.
Ethanol fuel can be produced renewably from numerous plant and waste materials, but harnessing the energy of lignocellulosic feedstocks has been particularly challenging in the development of this alternative fuel as a substitute for petroleum-based fuels. Consolidated bioprocessing has the potential to make the conversion of biomass to fuel an economical process by combining enzyme production, polysaccharide hydrolysis, and sugar fermentation into a single unit operation. This consolidation of steps takes advantage of the synergistic nature of enzyme systems but requires the use of one or a few organisms capable of producing highly efficient cellulolytic enzymes and fermenting most of the resulting sugars to ethanol with minimal byproduct formation while tolerating high levels of ethanol. In this review, conventional ethanol production, consolidated bioprocessing, and simultaneous saccharification and fermentation are described and compared. Several wild-type and genetically engineered microorganisms, including strains of Clostridium thermocellum, Saccharomyces cerevisiae, Klebsiella oxytoca, Escherichia coli, Flammulina velutipes, and Zymomonas mobilis, among others, are highlighted for their potential in consolidated bioprocessing. This review examines the favorable and undesirable qualities of these microorganisms and their enzyme systems, process engineering considerations for particular organisms, characteristics of cellulosomes, enzyme engineering strategies, progress in commercial development, and the impact of these topics on current and future research.
Although lignocellulosic biomass is traditionally considered to be composed of cellulose, hemicellulose, and lignin, each of these components does not exist individually. Structurally, they are chemically bonded to form lignin-carbohydrate complexes (LCC) instead of being simply physically attached. Thus, lignin-carbohydrate complexes actually define the original structure of lignocellulosic biomass and inherit a wide array of compositions and features. However, the role of lignin-carbohydrate complexes has neither been completely investigated nor understood in this respect. In this review, the basic structures of lignin-carbohydrate complexes, extraction methods, bonding patterns and their cleavage are briefly discussed. More efforts are put on the role of lignin-carbohydrate complexes in the extraction/ isolation of biopolymers and in the subsequent lignocellulosic biorefining processes. Finally, several design strategies for biomass pretreatment, biopolymer isolation, enzymatic hydrolysis etc. are proposed, and future research needs for industrial application of lignocellulosic biorefinery are explored. It is anticipated this review could provide both the fundamentals of LCC and its effect on the biomass utilization, in the meantime attract more scientists' attention on the basic research on LCC. (C) 2020 Elsevier Ltd. All rights reserved.
Sago fronds are agricultural waste, whose availability is enormous in Indonesia, yet not optimally utilized. This research was conducted to isolate nanocrystalline cellulose from sago frond material, using sulfuric acid, with variations in hydrolysis times and cationic modifications of the nanocrystalline cellulose surface. The profiles of Fourier transform infrared spectroscopy, a scanning electron microscopy, and X-ray diffraction indicated a decrease in lignin content, hemicellulose, and fiber dimensions, during the delignification, bleaching, and hydrolysis, followed by an increase in the cellulose content and in degrees of crystallinity. The variations in hydrolysis times affected the cellulosic nanocrystalline characteristics. Longer hydrolysis times caused a decrease in the yield, thermal stability, dimensions of nanocrystalline cellulose, and an increase in the degree of crystallinity and surface charge. The modification of nanocrystalline cellulose, using cetyltrimethylammonium bromide and 3-chloro-2-hydroxypropyltrimethylammonium chloride, led to the surface of nanocrystalline cellulose becoming positively charged followed by a decrease in the degree of crystallinity and thermal stability. The resulting nanocellulose had moderate stability and the potential to be applied in wider-scaled material processing.
Lignocellulosic biomass is one of the abundant renewable bioresources on earth. Its chemical composition, i.e., lignin hinders ethanol production and commercialization. Pretreatment processes are vital for efficient separation of the complex interlinked components and enhance the availability of every component, i.e., cellulose and hemicellulose. However, for the bioethanol production, a major barrier is the removal of strong lignin component which is highly resistant to solubilization and a major inhibitor for hydrolysis of cellulose and hemicellulose. Pretreatment of biomass is necessary to make it susceptible to microorganisms, enzymes, and pathogens. Consequently, for the ethanol production, pretreatment of lignocellulosic biomass process is very costly. The initial pretreatment approaches include physical, physicochemical and biological methods. It found out that; pretreatment methods have a significant impact on efficient production of ethanol from biomass. However, extensive research is still necessary for the development of new and more efficient pretreatment processes for conversion of lignocellulosic biomass to ethanol. Present review article presents recent development on lignocellulose biomass pretreatment. We discussed the different pretreatment methods along advantages, disadvantages, and challenges for bioethanol production. This review includes benefits and drawbacks and chemical, physical, physiochemical and biological pretreatment along with existing problems. For the production of ethanol, this review will help researchers regarding selection, development and further planning of pretreatment for different lignocellulosic residues.
Energy and waste disposal issues are calling for advanced recycling methods such as conversion of organic waste into biohydrogen and biomethane. Here we review factors that influence yields, such as pH, temperature, substrate composition, biocatalyst, nutrient content, volatile fatty acids concentration, organic loading rate, hydraulic retention time and C/N ratio. The optimum pH is 5.5-6 for hydrogen production, and 6.8-7.2 for methane production. Hydrogen yield improved highly after reducing the retention time from 72 to 20 h. The highest methane productivity was achieved with C/N ratio of 16-27. We also discuss methods to improve efficiency such as co-digestion, pre-treatment, application of additives and optimal digester design. Co-digestion synergizes the effects on microbial communities, balances the nutrients, reduces the inhibitory effects and improves the economic viability. Co-digestion has enhanced the productivity by 25-400\% compared to mono-digestion. Acid pre-treatment is the best method for lignocellulose hydrolysis, followed by enzyme pre-treatment. Microwave pre-treatment enhances the biomethane production 4-7 times. The batch mode improves the substrate degradation efficiency and hydrogen production by 25\% compared to the continuous mode. The addition of trace metals alters the hydrogenase activity during anaerobic fermentation. Reaction kinetics and metabolomics, bioaugmentation, digestate recirculation, frequent feeding and development of bioreactor systems for two-stage anaerobic digestion are also presented.
The consumption of fossil fuels in excess leads to chronic effect of greenhouse gas (GHG) emissions on the environment. These adverse environmental impacts of GHG have invoked reasonable awareness on renewable energy resources. Bioethanol from lignocellulosic agricultural residue (profusely available renewable raw materials in the tropical areas) exhibits promising alternative to the petroleum based fossil fuel which reduces the net emission of GHGs. But due to certain technological barriers the large scale production of lignocellulosic bioethanol has not been successfully commercialized. To achieve the goal, economically viable bioethanol production technology, which includes pretreatment, enzymatic hydrolysis, fermentation, and dehydration, needs to be developed. Ionic liquid aided pretreatment can recover more than 80\% cellulose and 42\% lignin from lignocelluloses, which generally contains 30-46\% cellulose and 18-25\% lignin. Processing of the recovered cellulose towards bioethanol production requires enzymatic hydrolysis, which gives almost 76\% reducing sugar yield. Use of ultrafiltration and nanofiltration in hydrolysis concentrates 27\% reducing sugar as well as recovers more than 73\% enzyme with 50\% catalytic activity. Ultrafiltration rejects 100\% yeast as well as reveals 15 g/l/h ethanol productivity, which can be subjected to membrane based dehydration by way of pervaporation to produce 99.8 wt\% ethanol. The scope of this review focuses on eco-friendly and sustainable method for bioethanol production. A holistic and dedicated approach of this review helps to solve the various technological concerns and realize large scale commercialization of lignocellulosic ethanol.
Different pretreatments strategies have been developed over the years mainly to enhance enzymatic cellulose degradation. In the new biorefinery era, a more holistic view on pretreatment is required to secure optimal use of the whole biomass. Hydrothermal pretreatment technology is regarded as very promising for lignocellulose biomass fractionation biorefinery and to be implemented at the industrial scale for biorefineries of second generation and circular bioeconomy, since it does not require no chemical inputs other than liquid water or steam and heat. This review focuses on the fundamentals of hydrothermal pretreatment, structure changes of biomass during this pretreatment, multiproduct strategies in terms of biorefinery, reactor technology and engineering aspects from batch to continuous operation. The treatise includes a case study of hydrothermal biomass pretreatment at pilot plant scale and integrated process design.
In the present study, ozone assisted autohydrolysis (OAAH) was evaluated for enhanced generation of xylooligosaccharide (XOS) from wheat bran. The total XOS yield with optimum ozone dose of 3\% (OAAH-3) was found to be 8.9\% (w/w biomass) at 110 degrees C in comparison to 7.96\% at 170 degrees C by autohydrolysis (AH) alone. Although, there was no significant difference in oligomeric composition (DP 2-6), significant decrease in degradation products namely furfural (2.78-fold), HMF (3.15-fold), acrylamide (nil) and acetic acid (1.06-fold), was observed with OAAH-3 as a pretreatment option. There was 1-fold higher xylan to XOS conversion and OAAH-hydrolysate had higher DPPH radical scavenging activity than AH. PCA plots indicated clear enhancement in XOS production and lower generation of inhibitors with decrease in treatment temperature. Results of the study therefore suggest OAAH can be an effective pretreatment option that can further be integrated with downstream processing for concentration and purification of XOS.
Lignocellulosic materials can be explored as one of the sustainable substrates for bioethanol production through microbial intervention as they are abundant, cheap and renewable. But at the same time, their recalcitrant structure makes the conversion process more cumbersome owing to their chemical composition which adversely affects the efficiency of bioethanol production. Therefore, the technical approaches to overcome recalcitrance of biomass feedstock has been developed to remove the barriers with the help of pretreatment methods which make cellulose more accessible to the hydrolytic enzymes, secreted by the microorganisms, for its conversion to glucose. Pretreatment of lignocellulosic biomass in cost effective manner is a major challenge to bioethanol technology research and development. Hence, in this review, we have discussed various aspects of three commonly used pretreatment methods, viz., steam explosion, acid and alkaline, applied on various lignocellulosic biomasses to augment their digestibility alongwith the challenges associated with their processing. (C) 2014 Elsevier Ltd. All rights reserved.
Chestnut shell (CNS) is one kind of promising feedstocks for the production of chemicals and biofuels. To effectively utilize CNS, a combined ethylene glycol-HClO4-water (88.8:1.2:10, w/w/w) pretreatment at 130 degrees C for 30min with dilute NaOH (1 wt\%) extraction at 90 degrees C for 1 h was employed to pretreat CNS. The porosity, morphology, and crystallinity of the pretreated solid residue were correlated with the enhancement of enzymatic saccharification. It was found that dilute NaOH extraction of CNS pretreated by acidified aqueous ethylene glycol media could be effectively saccharified. After 72 h, the reducing sugars and glucose from the hydrolysis of 50 g/L pretreated CNS by a cocktail of enzymes could be obtained at 77.8\% and 65.4\% yield, respectively. Finally, the recovered hydrolyzates containing glucose had no inhibitory effects on the ethanol fermenting microorganism. In conclusion, this combination pretreatment has high potential application in future. (C) 2015 Elsevier B.V. All rights reserved.
The search for alternative fuel sources to replace non-renewable energy is a highly relevant topic in current research studies. Both biomethane and biohydrogen can be obtained from several anaerobic biological processes, which have some advantages over traditional energy supply chains, especially due to the ability to use various wastes and/or wastewaters as feedstock for the biogas production, which is considered a renewable fuel. These features combined with low energy inputs support the potential of these processes to play a key role in replacing fossil energy sources in the coming decades, as well as helping to avoid climate changes. Thus, it is essential to accurately determine the composition of the biogas generated in different biological processes, regardless of the application: from lab-scale studies to industrial plants. In this work, a gas chromatography set consisting of a Shimadzu/TCD GC-2030 equipped with a Supelco Carboxen 1010PLOT column was used to determine hydrogen (H-2), nitrogen (N-2), methane (CH4) and dioxide carbon (CO2) by a low-cost manual injection procedure{''
Rice bran is a brownish powder layer that covers the rice grain, being a co-product generated during the grain milling process and is usually underused for animal feed or burned as a low-cost fuel. However, comprising between 5 and 10 wt\% of the rice grain, this biomass is a source of minerals, fatty acids, fiber and sterols, containing also up to 25 wt\% of oil. Because it contains an active lipase in its composition that hydrolyses its triglycerides into free fatty acids, crude rice bran oil typically contains a high acidity that makes its consumption unfeasible. Moreover, the defatted or de-oiled biomass is a lignocellulosic material which, through an adequate pre-treatment to reduce its recalcitrant structure, can be used in different sector, especially to produce biofuels. Given its functionality, this review describes recent scientific approaches to how rice bran is being used to prepare biofuels (mainly biodiesel from rice bran oil, or bio-oil, biochar, biogas, biohydrogen, bioethanol, and biobutanol from defatted biomass). Furthermore, the properties and characteristics that motivate the use of this material to synthesize fuels are reviewed, the main pre-treatment techniques necessary to remove part of the lignin from its lignocellulosic matrix and allow the digestibility of cellulose and hemicellulose as well as the challenges for the expansion as an energetic feedstock.
The main objective of the present work is to investigate the influence of nickel to cerium ratio on hydrogen exchanged Zeolite Socony Mobil-5 (HZSM-5) towards the catalytic upgrading of pine derived oxygenated pyrolysis vapours into aromatic hydrocarbon and phenol in pyrolysis oil via ex-situ fixed bed reactor. The presence of CeO2 could change electron density of Ni, promote the reduction of Ni species, accelerate the transfer of carbon species, and suppress the production of carbon deposits (17.53\%-25.11\%) compared with the parent HZSM-5 catalyst (28.95\%); it also improved the hydrodeoxygenation ability of all xNiyCe/HZSM-5(nickel and cerium bimetal modified HZSM-5) catalysts, resulting increases in noncondensable gas content (from 31.46\% to 52.99\%-65.53\%). Ni to Ce ratio of 1:1 and 1:2 produced highest aromatic hydrocarbon (32.14\%) and phenols (55.51\%) relative peak areas. The acid center of HZSM-5 and the metal acid center of the Ni:Ce = 1:1 catalyst obviously fine-tuned the formation of coke; and promoted hydrocarbon production. Moreover, high Ni content promoted alkylation of benzene at C6-C9 and increased C10(+) PAHs relative peak area; high Ce content promoted the formation of olefin and Increasing the cleavage of C-O bonds and promoted hydrogenation or dehydrogenation, reduced polycyclic aromatic hydrocarbons and coke yield, and increased phenols and alkylphenols selectivity. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
The paper provides an updated review on thermal conversion of biomass for the production of liquid products referred as bio-oil. This technology is described focusing on the characterization of feedstock, reactor design, products formation and upgrading. For feedstock characterization is covered in terms of several pretreatment methods. The reactor designs are illustrated number of design ranging from fixed bed to circulating fluidized bed. The properties of bio-oil composition have caused increasingly extensive research to be undertaken to address properties that need modification and this area is reviewed in terms of physical, catalytic and chemical upgrading. The mechanism of the products formation is also illustrated by several chemical routes. Reactor parameters such as heating rate, temperature of pyrolysis, catalysts etc are reviewed. (C) 2012 Elsevier Ltd. All rights reserved.
In this work, a rapid one-pot hydrated deep eutectic solvent (DES) pretreatment was proposed to facilitate the conversion of carbohydrates from lignocellulosic biomass to monosaccharides. Specifically, the pure and hy-drated DES based on benzyl triethylammonium chloride (BTEAC), formic acid (FA) and water was used to pretreat bamboo shoot shells (BSS) by microwave heating. The pretreated solid residues were enzymatically saccharified to produce fermentable sugars, and the hydrolyzed carbohydrates and lignin remained in the hy-drolyzate. The results showed that the yield of monosaccharides from the hydrated DES hydrolyzate (193.7-228.4 g/kg) was significantly higher than that (45.9-66.1 g/kg) of pure DES. The 30\% hydrated DES pretreatment achieved the best glucose yield (89.03\%) and a total monosaccharides yield of 555.4 g/kg, which corresponded to a conversion ratio of carbohydrates to monosaccharides of 87.0\%. The proposed process is a robust method for the efficiently convert carbohydrates from BSS into monosaccharides.
Nowadays renewable energy with low prices is a global target that has taken the attention to compare alternatives energy sources with fossil fuels. Therefore, this study was established to find suitable and sustainable alternative low-cost fuels source. Cooking oil waste (COW) was mixed with non-pretreated citrus tree fibers (CTF) (0.5 mL to 1 g ratio) and pressed to formulate coal (CTF/COW). Otherwise, this mixture was subjected to in situ fungal pretreated using Aspergillus flavus isolate to simplify the mixture composition and pressed to offer in a usable form with enhancing their heating value for the first time. CTF/COW was characterized using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscope (SEM) and thermal analysis (TGA) before and after treatment. The fungal isolate was observed with enzyme productivity and activity of CMCase, avicelase, xylanase, mannanase, alpha-glucosidase, beta-glucosidase, lignin peroxidase and lipase according to enzyme assays and the chemical compositions of CTF before and after fungal treatment, where the best PH for enzymes extraction was between 5 and 7. The fungal enzymes increased the heating value by about two and half folds in comparison with non-pretreated coal. Moreover, the calorific value of tCTF/COW was 43,422 kJ/kg, which was higher than CTF recorded 18,214 kJ/kg and COW recorded 39,823 kJ/kg. Our result suggests that fungal treatment of the mixture of citrus trees and cooking oil waste presents as a promising low-cost and eco-friendly coal.
Brewers' spent grain (BSG) is an inexpensive and abundant brewery by-product that can be used to produce prebiotic arabino-xylooligosaccharides (AXOS). In this study, Bacillus subtilis 3610 was used, for the first time, to produce AXOS through direct fermentation of BSG. Additionally, the microorganism was genetically modified to improve the AXOS production. The xylanase gene xyn2 from Trichoderma reesei coupled with a secretion tag endogenous to B. subtilis was cloned in pDR111 and integrated into its chromosome. After optimization by experimental design, AXOS with a degree of polymerization ranging from 2 to 6 were obtained. The maximum production yield expressed in xylose equivalents per amount of BSG (54.2 +/- 1.1 mg/g) represents an increase of 33\% comparing to the wild type. When compared with the enzymatic hydrolysis process, single-step fermentation with B. subtilis proved to be a very promising low-cost strategy for the simultaneous production of AXOS and valorization of BSG.
Superhydrophobic oil sorbent was prepared by coating raw kapok fibers with titanium dioxide (TiO2) nano particles, followed by surface modification with 1H, 1H, 2H, 2H-perfluorooctyl-triethoxysilane (PTES). The TiO2 nanoparticles exhibited an anatase structure as confirmed by X-ray diffraction. Clusters of TiO2 nanoparticles were observed on the surface of the kapok fibers after hydrothermal process. On the other hand, Fourier transform infrared (FTIR) spectroscopy confirmed the effective attachment of PTES onto the TiO2-based kapok nanocomposite after surface modification. Maximum oil sorption capacities of modified kapok fibers were investigated using diesel, gasoline, chloroform and vegetable oil. The maximum sorption capacities were 44.78, 39.48, 61.94, and 72.79 g/g, respectively. This shows that the PTES modified kapok-TiO2 nanocomposite is very promising oil sorbent.
A novel process for simultaneous production of furfural and pretreatment of oil palm empty fruit bunch (EFB) by dilute acid pre-hydrolysis was developed based on non-isothermal kinetic modeling. Mass transfer analysis suggested that the internal diffusion could be neglected as diffusion time of sulfuric acid in EFB particles was significantly shorter than the pre-hydrolysis period, whereas the heating stage could not be neglected due to a significant part of xylan was solubilized at the stage. A strategy for increasing furfural yield was developed by intermittent discharging of steam, resulting in 71.4 \% furfural yield. The pretreated solids showed good enzy-matic digestibility. 136.3 g/L glucose corresponding to 81.6 \% yield was obtained by high-solid loading hy-drolysis. 95.4 g furfural and 212 g glucose could be obtained from 1 kg dry EFB. Therefore, non-isothermal effects on polysaccharide hydrolysis and pentose decomposition should be considered carefully for an efficient process design of EFB biorefining.
A magnetic carbon nanofiber sorbent was facilely synthesized from bio-based bacterial cellulose and FeCl3 via impregnation, freeze-drying, followed by pyrolysis at 700 degrees C, without additional activation or nanofiber fabrication. The obtained material possessed intrinsic 3D naturally fibrous and porous structure with good magnetization. The adsorption results showed that the adsorption capacity of the prepared adsorbent towards bisphenol A (BPA) was as high as 618 mg/g, outperforming other adsorbents. Moreover, recycling the adsorbent for 10 consecutive cycles retained 96\% of initial adsorption efficiency. The magnetic sorbent can maintain good magnetic properties even with recycling. Hence, the use of bacterial cellulose as a renewable carbon nanofiber precursor and FeCl3 as a source of magnetic particles, and a green pore generating agent in the present protocol, lead to a superior magnetic carbon nanofiber adsorbent with sustainable characteristics.
Glycerol-assisted one-step instant catapult steam explosion (ICSE) was studied for corn stover pretreatment. Glycerol addition reduced lignin content from similar to 32 \% to similar to 24 \% in pretreated solid residues with a stover/glycerol ratio from 1:0.0 to 1:2.0. Glycerol addition might help to reduce the formation of pseudo-lignin with the reduction of the total lignin recovered in pretreated solid residue from 114 \% (possibly because of pseudo-lignin contribution) to 81 \%. Furthermore, atomic forced microscopy analysis showed that glycerol addition improved surface roughness of pretreated corn stover. Moreover, it was proposed that glycerol-assisted ICSE likely led to the reactions of glycerol with lignin and lignin-derivatives through alpha-etherification and gamma-esterification, preserving lignin internal beta-O-4 linkages and preventing lignin condensation. Finally, enzymatic hydrolysis of corn stover pretreated by glycerol-assisted ICSE at a stover/glycerol ratio of 1:1 led to a glucan digestibility in solid residues of 98.4 \% and a glucose yield of 79.3 \%, which were 27.9 \% and 44.7 \% higher than those without glycerol addition, respectively.
The development of advanced biofuels from waste organic matter, such as lignocellulosic biomass, is critical for global sustainable waste management and to delay climate change by reducing greenhouse gas emissions via partial replacement of fossil fuels. However, the inherent recalcitrance of lignocellulosic biomass due to the presence of inhibitory components, mainly lignin, limits the hydrolysis of its carbohydrate content, representing a key hurdle augmenting biofuel production. Therefore, pretreatment of lignocellulosic biomass is crucial to promote its fragmentation, increase its surface area and solubility, and lower the cellulose crystallinity and lignin content for sustainable biorefinery. Conventional pretreatment processes have several drawbacks, including high operational costs, corrosion of equipment, and generation of toxic effluents and by-products. To offset the negative impacts of these limitations on biofuel production, here, we have discussed and critically compared various eco-friendly approaches for the efficient conversion of biomass to ensure high yields of biofuels as a commercial solution. Moreover, a range of microbes and enzymes have been highlighted that effectively utilize lignocellulosic biomass to obtain energy and convert its complex polymeric structure into a biodegradable one, facilitating its subsequent valorization. Furthermore, the importance of multi-omics approaches was discussed to gain functional insights into the lignocellulolytic microbial communities and their interspecies symbiosis during the hydrolysis of organic biomass. Finally, the limitations of previous studies, challenges, industrial perspectives, and future outlooks for the development of economical, energy-saving, and eco-friendly strategies toward the sustainable valorization of lignocellulosic biomass were summarized.
Lignocellulosic biomass is a promising feedstock for sustainable production of non-food building-block sugars. This bioconversion process is preferentially carried out through the whole slurry enzymatic saccharification of the pre-treated lignocellulosic substrates. However, dissolved lignin, residual lignin, and lignin-derived phenolic molecules in the pre-treated biomass slurry can all trigger the decrease in activity and stability of cellulases, as well as the unfavorable enzyme recyclability. The hydrolyzing efficiencies can be considerably hindered by the lignin-induced non-productive binding of cellulases through various mechanisms. Three major non-covalent forces, i.e., hydrophobic, electrostatic, and hydrogen bonds interactions, can occur between the amino acid residues in cellulases and the functional groups in lignin. Various strategies such as enzyme engineering, substrate modification, additive blocking have been intensively developed to minimize the cellulase-lignin interactions. To investigate the impacts and benefits of different mechanisms and processes, this paper provides a systematic overview of the current opinions about the non-productive binding of cellulase to lignin. Through better understanding of their interactions it is our hope that the enzyme binding groups in lignin could be properly quenched by using new pre-treatment methods and/or biochemical processing strategies to increase the efficiency of cellulose bioconversion. (c) 2016 Society of Chemical Industry and John Wiley \& Sons, Ltd
Lignocellulose represents a potential supply of sustainable feedstock for the production of biofuels and chemicals. There is, however, an important cost and efficiency challenge associated with the conversion of such lignocellulosics. Because its structure is complex and not prone to undergo chemical reactions very easily, chemical and mechanical pretreatments are usually necessary to be able to refine them into the compositional building blocks (carbohydrates and lignin) from which value-added platform molecules, such as glucose, ethylene glycol, 5-hydroxymethylfurfural, and levulinic acid, and biofuels, such as bioderived naphtha, kerosene, and diesel fractions, will be produced. Conventional (wet) methods are usually polluting, aggressive, and highly energy consuming, so any alternative activation procedure of the lignocellulose is highly recommended and anticipated in recent and future biomass research. Lignocellulosic plasma activation has emerged as an interesting (dry) treatment technique. In the long run, in particular, in times of fairly accessible renewable electricity, plasma may be considered as an alternative to conventional pretreatment methods, but current knowledge is too little and examples too few to guarantee that statement. This review therefore highlights recent knowledge, advancements, and shortcomings in the field of plasma treatment of cellulose and lignocellulose with regard to the (structural and chemical) effects and impact on the future of pretreatment methods.
Oil palm empty fruit bunches (OPEFB) were pretreated with imidazole aiming to reduce the biomass recalcitrance and to co-produce ethanol and succinic acid. For such as purpose, two different yeasts (Saccharomyces cerevisiae and Pichia stipitis) were evaluated and compared. Imidazole pretreatment of OPEFB at 180 degrees C for 1 h achieved a removal of 81.5\% of lignin and a solid recovery of 53.0\%. Enzymatic hydrolysis (24 h) of imidazole-pretreated OPEFB achieved 96.2\% and 98.8\% of glucose and xylose yields, respectively. Fermentation of the enzymatic hydrolysate with S. cerevisiae resulted in higher ethanol titer (8.9 g/L) and productivity (0.75 g/L/h) with lower fermentation time (12 h) compared to the fermentation (48 h) using P. stipitis (6.3 g/L and 0.13 g/L/h). Additionally, 1.11 g/L and 1.83 g/L of succinic acid were produced by S. cerevisiae (12 h) and P. stipitis (48 h), respectively. From a biorefinery sight, a total of 132.5 kg of ethanol and 16.4 kg of succinic acid could be produced from a ton of raw OPEFB, employing S. cerevisiae in a 12-h fermentation of the enzymatic hydrolysate obtained from imidazole-pretreated OPEFB. The results showed great potential of imidazole-pretreated OPEFB for ethanol production using S. cerevisiae, leading to efficient lignocellulosic biomass valorization and minimization of the agro-industrial waste.
In this work, we report that FeCl3, a benign Lewis acid, could be used as a catalyst in the gamma-valerolactone (GVL)/H2O solvent system to facilitate efficient pretreatment of Chinese silvergrass. The results showed that approximately 87.8\% of xylan and 75.8\% of lignin were removed by 80\% GVL under 170 degrees C using 50 mM FeCl3 as a catalyst. The solubilized carbohydrate fractions in the pretreatment liquor were mainly composed of monosaccharides (glucose and xylose) rather than oligosaccharides (glucose oligomers and xylose oligomers) and inhibitors (furfural, hydroxymethylfurfural, formic acid and acetic acid). Moreover, FeCl3 decreased the transesterification of GVL with hydroxyl groups on the cellulose surface and resulted in more easily degraded cellulose. Approximately 96.5\% of cellulose and 92.2\% of xylan in the pretreated Chinese silvergrass were converted to fermentable monosaccharides by 10 FPU/g cellulases. This study indicated that FeCl3-catalyzed GVL solvent could efficiently deconstruct biomass and increase the cellulose digestibility, which provided a novel, GVL-based pretreatment system for processing biomass. (C) 2021 Elsevier Ltd. All rights reserved.
In order to solve the environmental pollution caused by over-breeding of coastalEnteromorpha prolifera, co-pyrolysis ofEnteromorpha prolifera, andthe Ficus microcarpa lfor bio-oil was conducted in a fixed-bed reactor. Under the optimal process parameters (the heating rate: 20 degrees C/min, the pyrolysis final temperature: 550 degrees C, the N(2)flow rate: 250 ml/min, and holding time: 10 min), theEnteromorpha proliferaalone pyrolysis to maximize the liquid yield (42.97\%). In contrast, the yields and properties of pyrolysis products obtained from co-pyrolysis ofEnteromorpha proliferaandthe Ficus microcarpa lwere improved, which showed obvious superiority. The bio-oil obtained fromEnteromorpha proliferaandthe Ficus microcarpa lyield increased up to 49.48\%, and the higher heating value of the liquid fraction was up to 28.86 MJ/kg (at 7:3). The density and acidity of the bio-oil reduced to 1.1111 g/cm(3)and 50.99 mgKOH/g (at 7:3), respectively. Addingthe Ficus microcarpa lcan improve the composition of the liquid phase. The GC-MS analysis result of the modified liquid fraction showed that the content of hydrocarbon compounds, alcohols, and esters increased, meanwhile the compound number of acids and aldehydes reduced. In addition, in non-condensable gases, the H(2)and C(n)H(m)concentration increased along with addingthe Ficus microcarpa l. This study provides a way for usingEnteromorpha proliferaandthe Ficus microcarpa lto product the bio-oil, at the same time, because of the cheapness of feedstocks, using them for easier industrialization of pyrolysis oil.
Bioethanol is considered the cleanest liquid fuel used as a substitute for depleting fossil fuels. Various technologies have been introduced to form bioethanol from lignocellulosic biomass. Seed pods of Bombax ceiba, which are produced and wasted in large amount annually, were used as a source of cellulose. In this study, response surface methodology was used to explore the effects of KOH concentrations, substrate loading, and residence time on cellulose exposure and liberation of reducing sugars (RS), total sugars (TS), and total phenolic compounds from seed pods of B. ceiba. Box-Behnken design with three variables and three levels showed maximum release of total phenolic compounds (394.04 mg/ml) and RS (50.06 mg/ml) corresponding to 3\% KOH concentration, 15\% substrate level with residence time of 8 h at 121 degrees C, and maximum cellulose exposure (64\%), and TS (206.65 mg/ml) liberation was observed at 5\% KOH concentration and 10\% substrate level at same temperature for same soaking time. While at room temperature maximum cellulose exposed (46\%), TS (146.1480 mg/ml), total phenol (300.3901 mg/ml), and RS (9.0075 mg/ml) were observed at 3\% KOH, 15\% substrate concentration, and 8-h residence time. These results suggested that thermochemical pretreatment is more effective than chemical pretreatment alone. The second-order polynomial equation using analysis of variance was employed for analyzing the results.
Corn stalk was modified using graft copolymerization to produce absorbent (AGCS), which was characterized by elemental analysis, fourier transform infrared, X-ray diffraction, solid-state CP/MAS C-13 NMR spectra, thermogravimetric analysis and differential scanning calorimeter. AGCS, having cyano group (-CN) after grafted successfully, exhibits more high adsorption potential for Cd(II) than unmodified forms. The efficiency of AGCS for removal of cadmium ions was evaluated. Factors affecting Cd(II) adsorption such as pH value and adsorbent dosage were investigated. More than 90\% removal was achieved at pH 3.0-7.0 and the adsorption increased from 16.0\% to 99.2\% with increase of adsorbent dose. In addition, two isotherm models, namely. Langmuir and Freunlich were also analyzed to determine the best fit equation for adsorption of Cd(II) on AGCS. (C) 2010 Elsevier Ltd. All rights reserved.
Nuclear magnetic resonance (NMR) spectroscopy has been applied worldwide to study the chemical composition of lignocellulosic biomass and to analyse changes resulting from the chemical processing of these materials. In this work, solid-state C-13 NMR was used to study the lignin contents of a large set of lignocellulosic materials derived from various Brazilian plant species. To determine the lignin content by NMR, the integrated intensity of the deconvoluted signal due to methoxyl groups in the C-13 NMR spectra was used to obtain a calibration curve using mixtures of cellulose and lignin standards. The lignin contents obtained by NMR were, in general, in good agreement with the results obtained by methods based on acid hydrolysis (AH). For some samples, the NMR results showed that the AH methods were ineffective for the complete carbohydrate hydrolysis, indicating that the NMR-derived values represented more reliable estimates of the lignin contents in these cases.
Cassava pulp is one of the most abundant agricultural residues that can cause serious disposal problems. This study aimed to apply a biorefinery approach by examining the feasibility of microwave-assisted cassava pulp hydrolysis to attain sustainable management and efficient use of natural resources. Four factors, namely, the liquid-to-solid ratio (20 mL/g, 10 mL/g, 7.5 mL/g, and 5 mL/g), types of acids (H2SO4 and H3PO4), watt power (600 W, 700 W, and 800 W) and time (3, 5 and 8 min), were carefully investigated. The highest fermentable sugar content of 88.1 g/L +/- 0.7 g/L (0.88 g fermentable sugars/g dry cassava pulp) was achieved when 20 mL/g cassava pulp was hydrolyzed with 2.5\% (v/v) H2SO4 under microwave irradiation at 800 W for 8 min. Glucose was a major product (82.0 g/L +/- 5.2 g/L). The inhibitor concentration was 5.17 g/L +/- 0.01 g/L, and the levulinic acid concentration was 5.15 g/L +/- 0.01 g/L. The results indicated that the liquid-to-solid ratio, diluted acid concentration, irradiation watt power and time were important factors in producing fermentable sugars from acid hydrolysis under microwave irradiation. The crude hydrolysate was used for PHB production by Cupriavidus necator strain A-04. The hydrolysate to nutrients ratio of 30:70 (v/v) yielded a cell dry weight of 7.5 g/L +/- 0.1 g/L containing PHB content of 66.8\% +/- 0.3\% (w/w), resulting in a yield YP/S (g-PHB/g-S-PHB) of 0.35 g/g. This study demonstrated that the microwave assisted cassava pulp hydrolysate developed in this study provided a high amount of glucose (88.1\% conversion) and resulted in a low concentration of inhibitors without xylose; this was successfully achieved without pregelatinization, alkaline pretreatment or detoxification.
Various bioactive agrowastes derived phenolic compounds (APCs) obtained from agrowastes lignin hydrolyzed methods and evaluated for their potential antioxidant, antimicrobial and anti-quorum activities with special reference to food borne pathogens. Half-maximal inhibitory concentrations (IC50) of isolated phenolic compounds against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals have been found in the range of 53-84 mu g/mL, whereas samples obtained by hydrolysis in absence of acid have shown the (IC50) values of \~{
The present work was aimed at studying the production of lignocellulolytic enzymes, namely cellulase, xylanase, pectinase, mannanase, and laccase by a newly isolated bacterium Sphingobacterium sp. ksn-11, utilizing various agro-residues as a substrate under submerged conditions. The production of lignocellulolytic enzymes was found to be maximum at the loading of 10\%(w/v) agro-residues. The enzyme secretion was enhanced by two-fold at 2 mM CaCO3, optimum pH 7, and temperature 40 degrees. The Field Emission Gun-Scanning Electron Microscope (FEG-SEM) results have shown the degradative effect of lignocellulases; cellulase, xylanase, mannanase, pectinase, and laccase on corn husk with 3.55 U/ml, 79.22 U/ml, 12.43 U/ml, 64.66 U/ml, and 21.12 U/ml of activity, respectively. The hydrolyzed corn husk found to be good adsorbent for polyphenols released during hydrolysis of corn husk providing suitable conditions for stability of lignocellulases. Sphingobacterium sp. ksn is proved to be a promising candidate for lignocellulolytic enzymes in view of demand for enzymes in the biofuel industry.
In this study, a novel capacitive deionization (CDI) technology by using silver nanoparticles and hierarchically ordered mesoporous carbons (HOMCs) as the anode and cathode electrodes, respectively, was developed to enhance the desalination efficiency of sodium ions. The TEM images show that HOMCs are 2-D hexagonal mesostructures with highly ordered 1-D strip-like channels and Ag is spherical with mean diameter of 30 nm. The electrochemical performance of HOMCs and activated carbons (ACs) show rectangular voltammograms at 5-100 mV s(-1), while two peaks with Faradic reaction occur for Ag electrode. The specific capacitance of HOMC electrode is 104.2 F g(-1) at 5 mV s(-1), which is 2.84 times higher than that of ACs. In addition, the asymmetric Ag parallel to HOMC electrodes show excellent electrosorption capacity and high stability toward sodium ion removal and the specific electrosorption capacity (SEC) is 356.3 and 251.6 mu mol g(-1) at 1.2 V in batch and continuous flowing solutions, respectively, which is 1.4-2.7 and 2.2-2.7 times higher than those of symmetric carbon-based electrodes. Results obtained in this study clearly indicate that the asymmetric Ag HHOMC electrode is a promising alternative nanomaterial which can open an innovative CDI technology to treat grey and brown waters that need high desalination efficiency. (C) 2016 Elsevier B.V. All rights reserved.
Adhesion forces between microparticles and substrates is a parameter of fundamental importance in studies of surfaces contamination and decontamination, filter and surface cleaning, non-contact sampling, and environmental and occupational health assessments. This parameter can be estimated theoretically or determined experimentally. Due to the specificities of the processes, the experimental determination is one of the best choices. Techniques commonly used to determine the particle-substrates adhesion forces include the atomic force microscopy (AFM), electric field detachment method, the aerodynamic detachment, and the centrifuge method. The capability to measure several particles simultaneously; and to determine the adhesion forces of regular and irregular real powders on smooth or rough surfaces in a single experiment, producing statistically reliable results are some advantages attributed to the centrifugation technique. This work aimed to use the centrifuge technique to determine adhesion forces between soot particles and cellulose ester membranes. The effects of the average particles size (11.1 to 29.0 mu m), powder consolidation relative centrifuge forces (press-on forces - 63.7, 255.0 and 1,593.6 RCF), and pore size of cellulose ester membranes (0.2 mu m and 0.8 mu m) were investigated. Adhesion forces between the soot and cellulose ester membrane substrates were directly affected by the press-on forces, by the average diameter of the soot particles, and by the pore size of the cellulose ester membranes. The theoretical models of Johnson-Kendall-Roberts (JKR) and of Derjaguin-Muller-Toporov (DMT) described the trend of adhesion forces as affected by the soot particle's diameter; although showed high deviation from the experimental data. Copyright (c) 2020 American Association for Aerosol Research
A process for the production of high bioethanol titre was established through fed-batch and simultaneous saccharification and fermentation (FB-SSF) of wild, non-edible cassava Manihot glaziovii. FB-SSF allowed fermentation of up to 390 g/L of starch-derived glucose achieving high bioethanol concentration of up to 190 g/L (24\% v/v) with yields of around 94\% of the theoretical value. The wild cassava M. glaziovii starch is hydrolysable with a low dosage of amylolytic enzymes (0.1-0.15\% v/w, Termamyl (R) and AMG (R)). The Automatic Gas Potential Test System (AMPTS) was adapted to yeast ethanol fermentation and demonstrated to be an accurate, reliable and flexible device for studying the kinetics of yeast in SSF and FB-SSF. The bioethanol derived stoichiometrically from the CO2 registered in the AMPTS software correlated positively with samples analysed by HPLC (R-2 = 0.99). (C) 2013 Elsevier Ltd. All rights reserved.
Amaferm,(R) a fermentation extract of Aspergillus oryzae, was fed as a top-dressing to dairy cows at 0, 1.5, 3, and 6 g/d in two lactation trials using 64 cows in 1989. Lactation trial 1 was conducted in the spring (March to May) and used 40 cows averaging 75 DIM for a 70-d treatment period. Lactation trial 2 was during the summer (June to July). Twenty-four cows averaging 140 DIM were employed m a 60-d study. Measurements included milk yield, feed intake, BW, rectal temperatures, respiration rate, and digestibility of CP, NDF, and DM. None of the levels of Amaferm had a significant effect on milk yield or composition, BW changes, or digestion coefficients in either trial. Cows fed 1.5 g/d of Amaferm had a higher DMI than those receiving 0 or 6 g in trial 1, and respiration rates were significantly higher for cows fed 3 g/d of Amaferm in trial 2. Under die conditions of this study, none of the levels of Amaferm affected the performance of lactating cows. Further elucidation of factors influencing response to Amaferm is needed.
In this study, carboxy-functionalized spherical cellulose nanoparticles have been produced from Alfa plant-derived cellulose microfibers (CMF) using ultrasonic-induced cellulose fragmentation process. CMF, with fiber diameter of 7.26 mu m and crystallinity of 87\%, were firstly produced from Alfa plant fibers and then subjected to surface carboxylation using TEMPO-mediated oxidation process. The as-resulted TEMPO-oxidized CMF (T-CMF), with an average diameter of 2.72 mu m, a crystallinity of 89\% and carboxyl groups content of 1032 mmol COO -/Kg cellulose, were then exposed to ultrasonication treatment for 45 min, resulting in the formation of cellulose nanospheres (CNS) with an average diameter of 33.96 +/- 7.01 nm and a crystallinity of 76\%. The carboxyl groups content on the surface of CNS was measured at 945 mmol COO -/Kg cellulose. This study demonstrated the importance of the ultrasonication process as a green method for producing CNS with interesting properties, which can be used in various potential functional applications.
The accumulation of construction spoil has brought great challenges to urban construction and environmental protection. It is an effective way to solve the problem of construction spoil accumulation by using construction spoil to sinter brick. At the same time, it can also reduce the waste of clay resources and farmland destruction caused by the production of sintered brick. Microwave sintering technology can greatly improve the sintering efficiency of materials. Sintering brick by microwave sintering technology can avoid a series of environmental problems in the traditional production process of sintered brick and can lead to an eco-friendly production of bricks. In this study, construction spoil was used as the raw material, and Al2O3, Fe2O3, and TiO2 powders were studied as MASM for improving the temperature rise rate and sintering efficiency of the brick in microwave sintering process. The characteristics of construction spoil brick sintered by microwave were studied by series experiments including unit weight, compressive strength, and meso-analysis. Results proven that microwave sintering technology is an efficient technology for brick making. The MASM can effectively increase the temperature rise rate of the sample and simultaneously improve the impermeability of the sample and sintering efficiency.
The limitation of xylan hydrolysis is a characteristic problem of sodium chlorite (SC) pretreatment, which greatly restricted the saccharification of SC-pretreated lignocelluloses. In this work, the effect of alkali incubation on the xylan hydrolysis of SC-pretreated poplar was investigated. SC pretreatment of poplar removed 84.7\% lignin, which yielded 71.2\% glucose and 60.0\% xylose under a cellulase loading of 20 filter paper units (FPU)/g dry matter (DM). The subsequent alkali incubation reduced the acetyl group, surface lignin, and surface chlorine contents of SC-pretreated poplar. Glucose and xylose yields were increased to 92.4\% and 86.3\%, respectively, by incubating SC-pretreated samples with 1.0\% NaOH at 50 degrees C for 1 h using a cellulase loading of 2 FPU/g DM. Both Tween 80 and xylanase improved the enzymatic hydrolysis yield of SC-pretreated poplar. Alkali incubation showed a 9-fold decrease in cellulase loading and increased the xylose yield of SC-pretreated poplar by 119.8\%. This work overcame the limitation of xylan hydrolysis in sodium chlorite-pretreated lignocelluloses and represented a novel method to efficiently saccharification of poplar with ultra-low cellulase loading. (C) 2021 Elsevier Ltd. All rights reserved.
Catalytic conversion of lignin to versatile aromatic compounds is attracting increasing attention. However, it is highly desirable but challenging to produce a specific chemical with high yield through lignin depolymerization in a one-pot process because of the complex structure of the lignin molecule (mainly composed of H, G, and S units). In this study, a series of metal-based deep eutectic solvents (M-DESs) were prepared and used for the catalytic tailoring of lignin H units to produce value-added methyl p-hydroxycinnamate (MPC). In particular, M-DES ChCl{[
The superficial chemical environment of the catalyst supports played an important role in heterometallic catalysts preparation. The functions of hydroxy groups on the surface of SiO2 nanosphere was investigated in catalyst preparing and cellulosic biomass conversion to ethylene glycol (EG). The results demonstrated that 15\% Ni-20\% W/SiO2-OH catalyst was favorable for EG production, with the highest yield of 63.1 and 42.1\% from microcrystalline cellulose and hardwood pulp, respectively. The characterization and activity tests suggested that the existence of hydroxy groups could promote the formation of more Ni-W alloys (e.g. NiW, Ni4W) under the same preparing condition, which supplemented and enhanced the incorporation of intrinsic nickel and tungsten catalytic activity, especially for enhancement of retro-aldol condensation reaction. Moreover, the metallic Ni-0 was generated in higher amount when supported on hydroxy-rich SiO2, boosting hydrogenation of the unsaturated intermediates. Finally, the reusability investigation of the catalyst implied that embedded Ni and W in alloys could inhibit leaching of metals in pressurized hot water.
Cellulose nanocrystals (CNCs) were extracted from Eucalyptus kraft pulp by sulfuric acid hydrolysis, and esterified with maleic anhydride (CNCMA). The incorporation of sulfate ester groups on the cellulose surface resulted in higher stability of the nanoparticles in aqueous suspensions and lower thermal stability. Then, PLA/CNC and PLA/CNCMA nanocomposites were successfully obtained by solution blow spinning (SBS) using dimethyl carbonate (DMC) as solvent. CNC and CNCMA indicated to be acting both as nucleating agents or growth inhibitors of PLA crystal and tends to favor the formation of PLA crystals of higher stability. A fraction of the nanocrystals indicate to be exposed on the surface of the PLA fibers, since the hydrophilicity of the composite films increased significantly. Such composites may have potential application as filtering membranes or adsorbents. (C) 2017 Elsevier Ltd. All rights reserved.
Distillers' grains (DGS), the main waste by-products of Chinese liquor industry, were used as substrate for surfactin production. Bacillus amyloliquefaciens MT45 could grow with DGS as sole carbon source to produce 1.04 g/l surfactin. However, low amylase activity of MT45 limited sugar supply and the subsequent surfactin production. Therefore, MT45 was co-cultured with Bacillus strains that exhibited remarkable hydrolases activities. Surfactin yield increased by 50\% when MT45 was co-cultured with B. amyloliquefaciens X82 that showed no product inhibition effect and did not develop extracellular matrix. The inoculation ratio of X82 greatly influenced the sugar supply, cellular growth, and surfactin production of the co-culture fermentation. Maximum surfactin titration (3.4 g/l) was obtained when MT45 and X82 were co-cultured with inoculation ratio at 1: 0.5, using 200 g/l DGS. This work highlights the feasibility of using industrial waste DGS as promising feedstocks to produce value-added surfactin by co-culture fermentation. (C) 2017 Elsevier Ltd. All rights reserved.
In this paper, the physical property and compressive strength of fire clay bricks incorporating combined fly ash (FA) and glass cullet (GC) were studied. Clay bricks were fabricated with the incorporation of FA-GC powder (FA: GC = 1:1) at 0, 2, 4, 6, and 8\% by weight of clay and fired at 950, 1050, and 1100 degrees C. The physical properties viz., firing shrinkage, porosity, density, and compressive strength were tested. The results showed that the increase in FA-GC content decreased the porosity and water absorption; and increased the firing shrinkage, bulk density, and strength of the fire clay bricks. The fire clay brick with a required compressive strength of over 17.2 MPa per ASTM C62-13a could be obtained with 4\% FA-GC and a low firing temperature of 950 degrees C. The linear firing shrinkage of this brick was 3.9\%, which was slightly higher than that without additive. The incorporation of FA increased the strength through the increased SiO2, Al2O3, and MgO from the ash. Whereas the GC acted as a flux and helped the fused-bonding of glass phase with clay, facilitated the crystalline quartz fusion, and enabled sintering at reduced temperature. As a combined additive, the GC-FA imparted a synergistic effect in producing fired clay brick at lower firing temperature and maintaining sufficiently high strength.
Surfactants play major role in the delignification of lignocellulosic biomass. Surfactant-assisted hydrothermal pretreatment was evaluated for chili post-harvest residue. Maximum reducing sugar yield of 0.445 g per g of dry biomass (g/g) was obtained when surfactant PEG 6000 was used. Compositional analysis revealed an efficient removal of lignin and hemicelluloses from the pretreated biomass. Fermentation inhibitors such as furfural, 5-hydroxymethylfurfural and organic acids were absent in the hydrolyzate. After pretreatment, the biomass can be directly hydrolyzed without any neutralization, washing and drying, and the hydrolyzate is devoid of major fermentation inhibitors. Fermentation with Saccharomyces cerevisiae yielded 1.84\% of ethanol with a fermentation efficiency of 63.88\%.
Xylan extraction by alkali is usually a prerequisite for traditional xylooligosaccharide (XOS) production from corncob. In this study, to avoid xylan isolation before XOS production, corncob was delignified by hydrogen peroxide-acetic acid (HPAA), followed by a two-step enzymatic hydrolysis for XOS and monosaccharide production. High lignin removal (55.5\%-82.6\%) was observed upon pretreatment with 75\%-100\% HPAA and using 50-100 mM H2SO4 as a catalyst. A high XOS yield of 27.8\% was obtained from 75\% HPAA-pretreated corncob with 75 mM H2SO4, and the xylose/XOS ratio was only 0.09, indicating that the purity of XOS was relatively high. The highest glucose yield (79.1\%) was obtained from 100\% HPAA-pretreated corncob with 50 mM H2SO4. Finally, 58.3 g of XOS, 186.9 g of glucose, and 56.4 g of xylose were obtained from 1 kg of corncob. This study provides a promising approach for XOS and monosaccharide production from corncob without xylan isolation.
Although beta-xylosidases have a wide range of applications, cold-active beta-xylosidases have been poorly studied. In this study, a cold active beta-xylosidase gene (xyl) from Bacillus pumilus TCCC 11,350 was cloned and overexpressed in Escherichia coli. The recombinant XYL (rXYL) was revealed to be a bifunctional enzyme with both beta-xylosidase and a-L-arabinofuranosidase activities. Purified rXYL was most active at 30 degrees C, demonstrating 26\% and 18\% of its maximum activity at 4 degrees C and 0 degrees C, respectively. Meanwhile, rXYL showed a 52\% activity in 200mM xylose, indicating a relatively strong tolerance to xylose. Moreover, rXYL exhibited a high synergistic effect (11.14-fold and 16.21-fold) with endo-xylanase to degrade beechwood xylan in both sequential and simultaneous reactions at low temperatures. As the first report on the novel cold-adapted beta-xylosidase from B. pumilus, these results suggested rXYL had attractive properties for food industrial utilizations.
Enzymatic pretreatment as an eco-friendly strategy has offered potential benefits in disintegrating cellulosic fibers into fibrils but limited by its high price. In this study, endoglucanase recycling was investigated in order to reduce endoglucanase expanses. Significant DP reduction can be achieved from 50.88\% to 76.96\% only by recycling liquid which included free endoglucanase. In the presence of fresh endoglucanase, no more pronounced reduction of DP was observed in all recycling rounds attributing to competitive adsorption between fresh and recycled endoglucanase. Fresh endoglucanase preferentially occupied active sites on cellulose surface, hydrolyzed amorphous region, and followed by degrading fibrils to saccharides together with recycled endoglucanase. This hypothesis was evidenced by increase of saccharides concentration when fresh endoglucanase was added. This study aims to provide theoretical support to decrease endoglucanase cost for deconstruction of fibers to fibrils in industrial manufacture.
The enzymatic degradation of lignocellulosic biomass such as apple pomace is a complex process influenced by a number of hydrolysis conditions. Predicting optimal conditions, including enzyme and substrate concentration, temperature and pH can improve conversion efficiency. In this study, the production of sugar monomers from apple pomace using commercial enzyme preparations, Celluclast 1.5L, Viscozyme L and Novozyme 188 was investigated. A limited number of experiments were carried out and then analysed using an artificial neural network (ANN) to model the enzymatic hydrolysis process. The ANN was used to simulate the enzymatic hydrolysis process for a range of input variables and the optimal conditions were successfully selected as was indicated by the R-2 value of 0.99 and a small MSE value. The inputs for the ANN were substrate loading, enzyme loading, temperature, initial pH and a combination of these parameters, while release profiles of glucose and reducing sugars were the outputs. Enzyme loadings of 0.5 and 0.2 mg/g substrate and a substrate loading of 30\% were optimal for glucose and reducing sugar release from apple pomace, respectively, resulting in concentrations of 6.5 g/L glucose and 28.9 g/L reducing sugars. Apple pomace hydrolysis can be successfully carried out based on the predicted optimal conditions from the ANN.
This work investigated the effects of temperature and of rate of heating on the kinetic parameters of pyrolysis of castor beans presscake, a byproduct generated in the biodiesel production process. Pyrolysis process was investigated by thermogravimetric analysis, and parameters were obtained from nonisothermal experiments. The results obtained from the process of thermal decomposition indicated the elimination of humidity and the decomposition of organic components of the biomass. DTG curves showed that the heating rate affects the temperature of maximum decomposition of the material. Kinetic parameters such as activation energy and pre-exponential factor were obtained by model-free methods proposed by Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Kissinger. Experimental results showed that the kinetic parameters values of the FWO and KAS methods display good agreement and can be used to understand the mechanism of degradation of the cake. In a generalized way, the results contribute to better understanding of the processes of biomass pyrolysis.
We report computed differential cross sections (DCSs) for electron impact excitation of the lower-lying states of both trans and gauche tautomers of ethanol, as well as total cross sections for the 15 eV-50 eV energy range. The Schwinger multichannel (SMC) method with pseudopotentials has been employed, and in our most sophisticated calculation in terms of multichannel coupling, 431 open target states have been considered. We found an overall good agreement with the available experimental data at intermediate scattering angles and at higher impact energies. Although we have used a Born-closure scheme for the higher partial waves, we have found discrepancies in the forward direction that were assigned to a poor description of the long-range component of the lower partial waves. Meanwhile, the lack of more Rydberg states could be related to the overestimated DCSs at lower energies. Missing open channels are usually evoked to explain the remaining discrepancies to experiment, but here, we argue that other factors should also be involved. Aiming at an improved description of the target states, we have proposed a simple procedure for selecting the pairs of hole and particle orbitals while keeping the single excitation prescription of the current SMC implementation. A quantitative assessment of the collision process should further consider the individual contribution of each tautomer, which presented quite distinct DCSs in some cases. Our computed excitation energies also support that the second absorption band of ethanol is comprised of three singlet states of each tautomer, rather than the previously suggested two or four states.
In this work, two analytical liquid chromatography methods were developed and compared for the characterization of aqueous phases from pyrolysis of lignocellulosic biomasses. NanoLC electron ionization-mass spectrometry (E1-MS) represents a novel and useful tool for a both separation and identification of semi/nonvolatile and a thermolabile molecules. The use of nanoscale flow rates, the highly reproducibility, and high detailed information on El spectra are the principal advantages of this technique. On the other hand, comprehensive 2D-LC, providing a two-dimen- 5 sional separation, increases the overall peak capacity lowering the occurrence of peak coelutions. Despite the use of reversed phase modes in both dimensions, a satisfactory degree of orthogonality was achieved by the employment of a smart design of gradient elution strategies in the second dimension incombination with photodiode array detection (PDA) and atmospheric pressure chemical ionization-mass spectrometry (APCIMS). Because of the absence of the preliminary extraction procedure, the fingerprint obtained for these samples results is independent of the extraction yield or contamination contrary to the gas chromatography-mass spectrometry (GC-MS) approach where a liquid liquid extraction of the water phase is necessary. The main classes of identified compounds were phenols, ketones, furans, and alcohols. The synergistic information on the two powerful analytical approaches, e.g., NanoLC El-MS and LC X LC, in the identification of such complex samples has never been investigated and fully benefit on the one hand from the superior degree of mass spectral information from El-MS and on the other hand from enhanced LC X LC compound separation.
This paper presents an economic optimization of a supply chain network to produce sugar and bioethanol from the first- and second-generation biomass in South Africa. A mixed-integer linear program model in combination with Google Earth(A (R)) and ArcGIS was hereby developed to account for sugar demand, different feedstocks and products, as well as their distribution, tax subsidies and different processing technologies to address bioethanol production. The model was applied to two case studies depending on availability of biomass of which the results showed that the integrated bioethanol and sugar supply chain network is economically viable in South Africa. Transportation costs accounted for a significant part of the costs incurred in the supply chain, while highest profits are made when higher amounts of raw materials are available and there is no restriction relating to ethanol production. It is concluded that the 2\% bioethanol-fuel blend target stipulated by the government of South Africa in the biofuel industrial strategy can be exceeded while still producing current amounts of sugar.
Lignocellulosic biomass is included in the group of renewable energy sources. Its calorific value is high, owing to which it can be successfully used in the production of second-generation fuels, e.g., biogas. However, its complex structure makes it necessary to apply a pretreatment in order to increase the biogas output. This study presents the usability of a pulsed electric field in grass silage pretreatment in methane fermentation and compares it with microwave-induced disintegration. The experiment shows that substrate disintegration with a pulsed electric field (PEF) results in an increase in methane output. The productivity of methane from PEF pretreatment silage increased by 20.1\% compared to the untreated control. The application of microwave disintegration, with the assumption that the same energy is used for the pretreatment, resulted in a methane output increase of 6\% compared to the control. The highest biogas production output in PEF-pretreated samples was 535.57 NL/kg VS, while the highest biogas output from substrates pretreated with microwaves was 487.18 NL/kg VS.
A novel enzyme Bi76 comprising GH10, E\_set\_Esterase\_N, and CE1 modules was identified, with the highesthomology (62.9\%) with a bifunctional endoxylanase/feruloyl esterase among characterized enzymes. Interestingly, Bi76 hydrolyzedglucan substrates besides xylans and feruloylated substrates, suggesting that it is thefirst characterized trifunctional endoxylanase/endoglucanase/feruloyl esterase. Analyses of truncation variants revealed that GH10 and E\_set\_Esterase\_N + CE1 modulesencoded endoxylanase/endoglucanase and feruloyl esterase activities, respectively. Synergism analyses indicated that endoxylanase,alpha-L-arabinofuranosidase, and feruloyl esterase acted cooperatively in releasing ferulic acid (FA) and xylooligosaccharides fromferuloylated arabinoxylan. The interdomain synergism of Bi76 overmatched the intermolecular synergism of TM1 and TM2.Importantly, Bi76 exhibited good capacity in producing FA, releasing 5.20, 4.38, 2.12, 1.35, 0.46, and 0.19 mg/g from corn bran,corn cob, wheat bran, corn stover, rice husk, and rice bran, respectively. This study expands the trifunctional endoxylanase/endoglucanase/feruloyl esterase repertoire and demonstrates the great potential of Bi76 in agricultural residue utilization.
Highly stretchable polyvinyl alcohol (PVA) films with a strain at break of around 700\% were obtained from solutions in trifluoroacetic acid (TFA). Structural and chemical analysis by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (ATR-FTIR) showed that TFA is retained by PVA via hydrogen bonds between the carboxylic acid groups and the hydroxyl groups of the polymers causing a strong plasticizing effect. Additionally, composites of PVA with cellulose could be developed using TFA as common solvent. The morphological and mechanical properties of the polymer composites could be accurately tuned by modifying the relative concentrations of the two polymers. Data from water adsorption isotherms and wetting measurements indicated that the presence of trifluoromethyl groups in PVA render the composite films relatively hydrophobic. (C) 2015 Elsevier B.V. All rights reserved.
Zizania latifolia commonly known as wild rice grass which is available in huge quantities in Loktak Lake is a major concern as it occupies a large area of the Lake and causing a several environmental problems. The investigation of present study was to evaluate possibilities of using Zizania latifolia as feed stock for bioethanol production. The method involved the pretreatment with dilute acid or alkali followed by enzymatic hydrolysis with commercial cellulase. Acid pretreatment was performed with 10\% biomass loading with different concentration of acids (0.4-2\% w.v) and alkali (0.25-1.5\% w.v). Maximum sugar release of 457 mg.g was obtained from 10\% biomass loading and 2\% w.v of acids. Alkali pretreatment is not effective for this grass. Physicochemical characterization of untreated and treated biomass was carried out by XRD, FTIR, SEM and corresponding alterations in the chemical composition were also monitored. Results showed the feasibility of this grass as biofuel (bioethanol) feed stock and can be potential approach to address the sustainable utilization phumdis grasses of Loktak Lake for the production of value added product.
A new strain, Candida tropicalis UFMG BX 12-a, was found to produce higher yields of xylitol on poplar wood hemicellulose hydrolysate. The hemicellulose hydrolysate liquor was detoxified using a novel method we developed, involving vacuum evaporation and solvent separation of inhibitors which made the hydrolysate free of toxins while retaining high concentrations of fermentable sugars. The effect of the detoxification method on the fermentation was also reported and compared to well-known methods reported in literature. In this study, the new strain C. tropicalis UFMG BX 12-a was used on the detoxified hydrolysate to produce xylitol. It was also compared to Candida guilliermondii FTI 20037, which has been reported to be one of the best strains for fermentative production of xylitol. To further improve the efficiency of the fermentation process, these strains were immobilized in calcium alginate beads. The yield (0.92 g g(-1)) and productivity (0.88 g L-1 h(-1)) obtained by fermenting the wood hydrolysate detoxified by our new detoxification technique using an immobilized new Candida strain were found to be higher than the values reported in literature.
Size reduction is essential to utilize biomass in many applications. Production of fine particles from biomass chips is usually performed using milling machines that consume large amount of energy. Steam explosion (SE) is a promising method for reducing the size of biomass using less energy consumption because it utilizes thermal energy. In this study, we focused on the possibility of the SE method to produce fine particles with a size below 1 mm from wood chips. Sakura (Prunus spp., hardwood) and Japanese cedar (Cryptomeria japonica, softwood) chips with a size of 5-10 mm were used in this study. The effects of SE conditions - such as temperature and residence time - and of the biomass type on the biomass size reduction were investigated in detail. The energy consumption of SE was also calculated and compared with that of the conventional mill. We found that SE is an energy-efficient method for biomass milling. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.
In this work the cell growth and inulinase production by Kluyveromyces marxianus NRRL Y-7571 were investigated in a packed-bed bioreactor. For this purpose, seven experimental runs were carried out in order to verify the influence of the inlet air temperature and volumetric air flow rate on the process dynamics. The results showed that the manipulated variables affected significantly the process performance. The best condition for enzyme production was an inlet air temperature and volumetric now rate of 30 degrees C and 3 m(3) h(-1), respectively, reaching an activity of around 463 U gds(-1). The results obtained here can be useful in the scale-up and optimisation of packed-bed bioreactors configuration for inulinase production. (C) 2009 Elsevier Ltd. All rights reserved.
The social, economic, and environmental impacts of climate change have been shown to affect poorer populations throughout the world disproportionally, and the COVID-19 pandemic of 2020-2021 has only exacerbated the use of less sustainable energy, fuel, and chemical sources. The period of economic and social recovery following the pandemic presents an unprecedented opportunity to invest in biorefineries based on the pyrolysis of agricultural residues. These produce a plethora of sustainable resources while also contributing to the economic valorization of first-sector local economies. However, biomass-derived pyrolysis liquid is highly oxygenated, which hinders its long-term stability and usability. Catalytic hydrogenation is a proposed upgrading method to reduce this hindrance, while recent studies on the use of nickel and niobium as low-cost catalysts, both abundant in Brazil, reinforce the potential synergy between different economic sectors within the country. This review gathers state-of-the-art applications of these technologies with the intent to guide the scientific community and lawmakers alike on yet another alternative for energy and commodities production within an environmentally sustainable paradigm.
Arsenic (As) presence in surface reservoirs and groundwater is considered as an extremely alarming issue around the globe. The objectives of the present study were to evaluate the sorption potential of almond shell (ALS) and almond shell biochar (ASB) based sorbents for the removal of As(III)/As(V) from As-contaminated aqueous solutions. The maximum As(III) sorption capacity of ALS and ASB were 4.6 and 4.86 mg g(-1), respectively at an initial As concentration of 5 mg L-1, pH similar to 7.2 and sorbent dose of 0.6 g L-1. Similarly, in case of As(V) the maximum sorption capacities were reported as 3.45 and 3.6 mg g(-1) by ALS and ASB respectively. Almond shell biochar removed 10-25\% higher As(III)/As(V) compared to the ALS. The isotherm modeling results revealed that both for As(III) and As(V), Langmuir model presented the suitable fit to the equilibrium data compared to other model showing the monolayer sorption to be a dominant sorption mechanism. The FUR and XPS spectroscopy revealed that mostly -OH functional groups along with some other aromatic and/or aliphatic carbon- and oxygen-rich groups (C=C-C, -C-H, C==0) were responsible for As sorption by both sorbents. It is concluded that ASB can remove As, notably As(III) from water more efficiently compared to natural ALS. Overall, the results of this research reveal that biochar conversion of ALS can enhance the sorption capacity for As in contaminated waters such as drinking water and wastewater. (C) 2019 Elsevier Ltd. All rights reserved.
Diverse renewable resources, especially those obtained from residual agricultural wastes, are being exploited to reduce the impact of environmental damage. This study presents a method to produce purified cellulose extracted from locally planted pineapple leaves (Ananas comosus). The cellulose was extracted by maceration pretreatment. The heating times were varied. This method is a simpler and more effective approach to delignify the pineapple leaf fibers compared with conventional chemical pulping and bleaching processes. The chemical composition of the cellulose was investigated according to TAPPI standards and by structural analyses, namely Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The results indicated that the hemicellulose and lignin were partially removed from the cellulose. Chemical analysis confirmed that the cellulose content increased from 25.8\% (pineapple leaf fibers) to 70.9\% (macerated cellulose). The optimum heating time was 3 h. However, XRD showed that the extracted cellulose had a higher crystallinity index than the initial pineapple leaf fibers. These results indicated that pretreatment via maceration has good potential applications in the production of macerated cellulose.
In this investigation, a mixture of cassava (Manihot esculenta) solid waste and rubber seed oil was subjected to pyrolysis for liquid fuel production. A series of pyrolysis experiments was conducted with fixed composition of 50 g cassava solid waste and 150 mL rubber seed oil. The experiments were conducted using zeolite-A synthesized from rice husk silica and aluminum metal through sol-gel route and subsequently calcined at different temperatures as catalyst. The main purpose of this study was to investigate the effect of calcination temperatures of the catalyst on the chemical composition of the liquid fuel obtained. The pyrolysis experiment was commenced at room temperature and allowed to reach peak temperature of 350 degrees C, and the composition of liquid fuel produced was analyzed using gas chromatography-mass spectrometry (GC-MS) technique. The results of GC-MS analyses reveal that liquid fuels composed of a series of organic compounds, broadly belong to hydrocarbon, alcohol, ester, ketone, aldehyde, and acid. The results also display significant effect of the calcination temperatures of the catalyst on the composition of the liquid for hydrocarbon contents in particular, the fuel with the highest hydrocarbon content of 90\% was obtained using the catalyst calcined at 800 degrees C, suggesting that the use of the particular catalyst is the optimum condition. Based on the hydrocarbon content of the liquid fuels, it is concluded that the zeolites exhibited considerably high ability to enhance the formation of hydrocarbon and simultaneously suppress the formation of oxygenated compounds.
The regulation mechanism governing the xylanolytic activity in the strain Cellulomonas sp. IIbc was studied. High levels of activity were detected during the cultivation on cellulose as the only carbon source. No activity was produced with glucose, xylose or cellobiose cultures, but in the last one, the synthesis was de-repressed when the sugar concentration dropped to 0.2\%. The activity was not inhibited by glucose, cellobiose and xylose up to 1\% concentration. A basal constitutive synthesis was detected in nutrient broth cultures. At the same time, xylose and cellobiose acted as inducers of the xylanase activity.
Biomass conversion technologies yield unique products for which laboratory characterization of structure and properties is an ongoing challenge. In this study, Hansen solubility parameters are estimated using regularized regression as a platform for adaptable group contribution. A training set of small molecules and a set of biomass conversion molecules are parameterized using simple contributing groups. Regularized regression is then applied as a tool to reduce model complexity. This allows for flexible development of contributing groups, which are then down-selected to those which are most important, while avoiding overfitting. The model is built upon experimental data and uses only python and its science/data analysis libraries. The model also shows good agreement with other published work designed for ``pencil and paper{''
This work aimed to characterize and evaluate the energy potential of the residual biomass of genetically improved rice varieties (Pampeira rice and Catiana rice) introduced in the Brazilian market in 2016 and an indefinite variety of rice to establish a comparison. The two varieties of rice species enabled an increase in producers' profits of up to 57\% and therefore with high production of residues and without problems of supply. The thermogravimetric analysis (TGA), middle and near infrared spectroscopy were used to characterize the biomass. The TGA curves evidenced the degradation of lignocellulosic matter as hemicellulose and cellulose (120 degrees C and 350 degrees C) and lignin (350 degrees C and 600 degrees C). The middle and near infrared spectroscopy identified the main characteristic bands of the rice husks: O-H, Si-OH, -CH2, -CH3, C=O and C-O. The elementary analysis showed that the percentage of carbon 40.68\% and 42.29\% and the total lignin 33.21\% and 31.55\% for Catiana and Pampeira rice husk, respectively, have a good potential for generating useful energy. The higher heating values (HHV) 4409.50 kcal kg(-1) and 4488.00 kcal kg(-1) for Catiana and Pampeira risk husk evaluate and proven the energetic potential of these materials. On the other hand, the ash content determined is lower, which facilitates its application in the combustion process. The theoretical results showed that the lignin presents greater enthalpy of combustion, when compared with hemicellulose and cellulose, confirming the results of the experiments found in the work.
The goal of this study was to investigate how the use of high concentration of cellulase may impact the properties of the substrate and the reaction medium during the enzymatic hydrolysis of the sisal pulp. Enzyme concentration of 0.9 mL g(-1) was considered for hydrolysis of a sisal cellulosic substrate, and the results were compared with previous ones using 0.5 mL g(-1) as cellulase concentration. Nonhydrolyzed pulps and the liquors were withdrawn from the reaction medium and characterized by scanning electron microscopy, crystallinity index, average molar mass, length/thickness, and high-performance liquid chromatography (HPLC). The results indicated that the enzyme/substrate ratio impacted crystallinity variations during the reaction and the induction period for exoglucanase action. The concentration of 0.9 mL g(-1) led to a glucose yield (98\%, an almost quantitative conversion) higher than 0.5 mL g(-1) (89\%). Aiming to gain information on the post-burst phase (after 15 h), 1 g of sisal pulp was added, and the results demonstrated that the enzymes remained active, which can counterbalance the higher cost due to the use of high enzymes concentrations. This study deepened the understanding of the enzymatic hydrolysis of sisal cellulosic pulp, and the findings may also benefit investigations on other pulps. (C) 2019 Elsevier B.V. All rights reserved.
Lignocellulosic biomasses such as banana pseudostem are attractive cellulose sources for bioenergy production, and for the use in biorefinery processes. However, pretreatment of lignocellulosic material is required to remove hemicellulose and lignin, while increasing cellulose accessibility to enzymatic hydrolysis (i.e., decreasing biomass recalcitrance). The effect of different concentrations of acid (H2SO4), alkaline (NaOH) and peroxide (H2O2) pretreatments on the chemical composition, cellulose accessibility, and enzymatic digestibility of banana pseudostem were studied. The water insoluble solids (WIS) recovery was low (similar to 30\%) for the severe pretreatment conditions applied, indicating high material solubilization. Acid pretreatment completely removed the hemicellulose content, whereas alkaline and peroxide pretreatments reduced its amount to 4.38 and 8.68\%, respectively. In contrast, the lignin content increased (from 17.26 to 39.99\%) after severe acid pretreatment, while alkaline and peroxide pretreatments reduced the lignin content to 7.65\% and 7.17\%, respectively. In line with hemicellulose and lignin removal, the cellulose content increased from 60.84 to 75.48 and 74.37\%, respectively for alkaline and peroxide pretreatments, with no alteration for acid. Dye adsorption assays showed that alkaline and acid pretreatments resulted in high internal and external specific surface areas - indicative of high cellulose accessibility - when compared with peroxide pretreatments. Overall, alkaline and acid pretreatments resulted in the highest glucose yields from enzymatic hydrolysis of banana pseudostem, compared with peroxide pretreatment. In conclusion, concentrations of each pretreatment that led to the highest glucose yields was identified, confirming that the banana pseudostem is a great source of fermentable sugars, with high potential for biofuel production.
Xylanases are hydrolytic enzymes which cleave the b-beta, 4 backbone of the complex plant cell wall polysaccharide xylan. Xylan is the major hemicellulosic constituent found in soft and hard food. It is the next most abundant renewable polysaccharide after cellulose. Xylanases and associated debranching enzymes produced by a variety of microorganisms including bacteria, actinomycetes, yeast and fungi bring hydrolysis of hemicelluloses. Despite thorough knowledge of microbial xylanolytic systems, further studies are required to achieve a complete understanding of the mechanism of xylan degradation by xylanases produced by microorganisms and their promising use in pulp biobleaching. Cellulase-free xylanases are important in pulp biobleaching as alternatives to the use of toxic chlorinated compounds because of the environmental hazards and diseases caused by the release of the adsorbable organic halogens. In this review, we have focused on the studies of structural composition of xylan in plants, their classification, sources of xylanases, extremophilic xylanases, modes of fermentation for the production of xylanases, factors affecting xylanase production, statistical approaches such as Plackett Burman, Response Surface Methodology to enhance xylanase production, purification, characterization, molecular cloning and expression. Besides this, review has focused on the microbial enzyme complex involved in the complete breakdown of xylan and the studies on xylanase regulation and their potential industrial applications with special reference to pulp biobleaching, which is directly related to increasing pulp brightness and reduction in environmental pollution.
A new applicability of wastewater of dextran fermentation (WWDF) for biological production of succinic acid with A. succinogenes CCTCC M2012036 was reported in this work for the first time. Notably, K2CO3 was used instead of MgCO3 in the pH regulating process for operational feasibility and a cell immobilization methodology by attaching cells on cotton fibrous matrix was adopted for cell recycle. The initial sugar concentration as well as matrix usage was optimized by investigating the cell growth, succinic acid concentration and yield. A rotated fibrous bed bioreactor was designed and constructed in order to increase the total cell amount and facilitate mass transportation in the fermentation system, and an average succinic acid yield, concentration and productivity of 0.82 g/g, 56.5 g/L and 1.28 g/L/h were realized in the repeated fed-batch fermentation, respectively. This research gave light to the optimization of succinic acid production towards a more cost-effective and operable direction.
This study aimed to characterize nanocellulose extracted from cotton (Gossypium hirsutum) linters. The nanocellulose was subjected to electronic microscopy, thermal analysis. X-ray diffractometry, light scattering, and contact angle. The properties of the nanocellulose are considerably different from the linter. The acidic hydrolyses applied to extract the nanocrystals increased the crystallinity index and the hydrophilicity and decreased the thermal stability. On average, the nanocrystals were 177 nm long and 12 nm wide, with an aspect ratio of 19 when measured by microscopy. The light scattering results were coherent with the crystal dimensions. Cotton linter is a potential source of nanocellulose crystals, particularly to be used in the production of hydrophilic nanocomposites. Extraction of nanocellulose from raw cotton linter does not require pulping. (C) 2012 Elsevier Ltd. All rights reserved.
The aim of this work is to evaluate of the effect of incorporating nanofibrillated cellulose (NFC) and chitosan (CH) in a dual system as dry additives during papermaking for unbleached bamboo alkaline sulfite anthraquinone methanol (ASAM) under different beating revolutions. Pulp beating at 4000 and 6000 revolutions has comparable properties with varying dosages of NFC (5\% and 10\%) and different chitosan concentrations (0.5\%, 1, 1.5\%, and 2\%). Hand sheets of a basis weight (60 g/cm2) were produced and measured for thickness, tear, tensile, burst index, and resistance to folding under TAPPI standard methods. Results revealed that with an increase in the number of beating revolutions, there was a decrease in the value of freeness. All analyzed pulp had freeness values within the permissible amount of 300-500 mL in papermaking, except 10\% NFC, which was 244-190 mL at 6000 revolutions. Furthermore, the addition of chitosan to 1.5\% with 5\% NFC at 6000 beating revolutions enhanced the tensile index (85.16 Nm/g) and burst index (7.69 kPa. m2/g) in comparison to the sample control. The incorporation of nanofibrillated cellulose and chitosan significantly altered the physical and mechanical strength. Optimal alkaline sulfite anthraquinone methanol ASAM-enhanced paper properties are displayed with 5\% NFC and 1.5\% chitosan at 6000 beating revolutions.
Differences in the composition of cellulases would lead to different adsorption characteristic which is a key factor in the process of enzymatic hydrolysis treatment of microfibrillated cellulose (MFC) and MFC film preparation. The main purpose of this research was to study how complex cellulase (D cellulase) and endocellulase (R cellulase) with different composition and dosages (Cellulase dosage per gram of pulp, U/g) affect the performances of MFC and MFC film properties. Herein, D cellulase and R cellulase with different dosages were compared to treat bleached eucalyptus kraft pulp (BHKP) for MFC preparation. Enzyme activity and adsorption properties of the two cellulases were comprehensively studied. Meanwhile, the performances of MFC and MFC film were investigated. As a result, D cellulase possessed higher adsorption ratio than R cellulase, but R cellulase demonstrated higher adsorption rate than D cellulase. The crystallinity index (CrI), specific surface area (SSA) and morphology of MFC were tuned by the combination of two cellulases at different dosages. Among them, the CrI of MFC treated by two cellulases increased, respectively, and both reached the maximum when the enzyme dosage was 10 U/g. Elongation at break (E) and tensile strength (TS) of MFC film treated by R cellulase decreased continuously which maintained excellent physical strength at low cellulase dosage compared with D cellulase. According to their respective minimum oxygen permeability coefficients, the MFC film obtained by R cellulase pretreatment possessed the better barrier property compared with MFC film pretreated by Dcellulase. In general, this work shows that low-cost R cellulase, which allows MFC film to have good performances at low enzyme dosages, is more suitable than D cellulase for BHKP pretreatment to prepare MFC film.
This study explores the development of eco-friendly burnt clay bricks incorporating recycled waste marble powder (WMP). Waste marble powder was collected from the local marble industry and used to manufacture brick specimens at a local brick manufacturing facility with dosages ranging from 5 to 25\% by clay weight. The mechanical and durability performance of bricks incorporating WMP were investigated. The WMP produced lighter weight bricks with reduced linear shrinkage. It also decreased the compressive strength of bricks because of enhanced porosity, as shown by scanning electron microscopy (SEM) analysis. However, bricks incorporating up to 10\% of WMP achieved compressive strength values within the specified limits of the local building code. All tested bricks satisfied the minimum standard flexural strength requirements. Using 5\% WMP in fired clay bricks yielded similar efflorescence and resistance to sulfate attack compared with control bricks without WMP. Leaching tests on brick specimens indicated that leached species from WMP-modified bricks were well below regulatory thresholds. Full-scale implementation of WMP in burnt clay brick manufacturing could mitigate the landfilling of this by-product and lead to the development of eco-friendly, nonhazardous and economical masonry construction.
Fourteen ionic liquids (ILs) were obtained and characterized by nuclear magnetic resonance and infra-red spectroscopy. One of these liquids, n-butylammonium acetate, was used in the treatment of coir fiber prior to acid hydrolysis. For this purpose, the fiber was pulped with 8\% (w/w) sodium hydroxide for 6 h under 2.5 atm pressure at 137 degrees C and then treated with IL for 2 h at 90 degrees C. The samples were hydrolyzed in acetic acid at different concentrations and temperatures. The reducing sugar concentrations were determined in all samples, and the optimal hydrolysis conditions were established (32.2\% acetic acid at 122.4 degrees C). The reaction time was also studied, and the conversion was maximized at 3 h. Under the best hydrolysis conditions, crude fiber, pulping fiber, and IL-treated fiber were hydrolyzed to yield 8.53\%, 47.58\%, and 89.75\% of reducing sugars, respectively. (C) 2016 Elsevier Ltd. All rights reserved.
Solvent-free acetylation of rubberwood (Hevea brasiliensis Mull.Arg) with acetic anhydride (Ac2O) and by means of N-bromosuccinimide (NBS) as catalyst was carried out in an oil bath at 105 degrees C and 120 degrees C. The effect of catalyst concentration, temperature, and reaction time was studied. The extent of acetylation was measured by determining the weight percent gain (WPG), and the acetylated wood was characterized by FTIR-ATR, CP/MAS C-13 NMR, and XRD spectroscopy. The presence of NBS in concentrations between 1.0\% and 3.0\% elevated the acetylation rate to a great extent. WPG increased from 8.1\% without catalyst to 22.1\% for 2\% NBS concentration after 60 min reaction at 120 degrees C. Similarly, after 60-min reaction time at 105 degrees C, WPG with 3\% NBS concentration was 19.0\% compared to 7.6\% with un-catalyzed reaction under the same reaction conditions. The effect of microwave heating (MWh) on the NBS-catalyzed acetylation was also investigated. A significant level of modification was achieved within a few minutes of MWh. The hydrophobic properties and dimensional stability of the acetylated wood were elevated. NBS was found to be an effective catalyst for wood acetylation.
Corn fiber (CF) is an agroindustrial residue obtained from starch or corn syrup. Currently, there has been increasing research interest in lignocellulosic materials from these residual materials. Consequently, this paper is a novel approach that complements the structural and chemical characterizations already published in the literature for CF. In this study, isolation, chemical composition and characterization was conducted of hemicellulose by means of H-1 NMR and FTIR-ATR and Klason lignin by means of acid soluble lignin (ASL) and acid insoluble lignin (AIL) determination using UV spectrophotometry and Py-GC-MS. Hemicellulose was obtained after aqueous extraction, lipid removal, delignification and alkaline extraction. The isolated hemicellulose from CF confirmed the presence of arabinoxylan, which was similar to the results reported in the literature. The CF contained 8.0\% and 4.0\% ASL and AIL, respectively. Regarding lignin, the study identified more than 47 primary pyrolysis products for ASL, with 17\%, 20\% and 59\% relative molar abundance for lignin, carbohydrates, and other products, respectively, and 39 primary pyrolysis products with 44\% and 7\% relative molar abundance for lignin and carbohydrates, respectively. The main products derived from lignin were phenol, 4-methylphenol, guaiacol, 4-vinilguaiacol, syringol and syringylaldehyde. The peaks of lignin derivatives indicated that the Klason method is effective for lignin isolation, and the Py- GC-MS technique allowed for the identification of the presence of residual lignin in AIL and ASL from CF. In this context, lignocellulosic components of CF are chemically suitable for use as raw materials to transform biomass into high value-added products. {[
An unstructured-unsegregated temperature-dependent kinetic model was developed and validated to describe ethanol fermentation in a mixture of xylose and glucose for the nonconventional yeast Spathaspora passalidarum NRRL Y-27907 under high cell density in the temperature range of 26-32 degrees C. The kinetic model consisted of 13 equations and 16 kinetic parameters, describing cell growth, individual xylose and glucose uptake and product formation. Global parametric estimation was executed through a differential evolution algorithm. Temperature-dependent parameters were identified and adjusted to Arrhenius-type equations as a function of temperature. The overall r(2) of the process calibration and validation were 0.972 and 0.959, respectively, indicating that the model satisfactorily described the process in the temperature range investigated. Furthermore, using a 3D projection of the model to simulate ethanol production, it was concluded that temperatures between 30 and 32 degrees C resulted in the highest productivities.
To understand the effects of the biomass constituents for enzymatic hydrolysis, a tropical hardwood, Eucalyptus pellita, was employed to change the content of chemical constituents and regression assessment was progressed. The liquid hot water and acid-chlorite pretreatment controlled hemicellulose and lignin removal rate from 3.1 to 91.7\% and from 4.4 to 99.1\%, respectively. Total lignin in E. pellita (34.8\%) was obviously reduced up to 9.0\% under 4 g of sodium chlorite and 0.8 mL of acetic acid with 3 times loading. In this case, acid-insoluble lignin (2.4\%) was entirely eliminated compared with that of E. pellita (29.0\%), whereas acid-soluble lignin (6.6\%) was preferably increased compared with of E. pellita (2.3\%). The maximum glucose yield (87.5\%) after the combined pretreatment and enzymatic hydrolysis were dramatically improved compared with that of liquid hot water pretreatment alone (28.2\%). Meanwhile, a high glucose yield (83.9\%) could also be obtained by acid-chlorite pretreatment alone. The adjusted R-squared value of hemicellulose and lignin removal rate (0.9285) and lignin removal rate alone (0.9063) with glucose yield was determined by linear regression analysis. (C) 2019 Published by Elsevier Ltd.
High-solids submerged cultivation for microbial production of industrially relevant enzymes can be facilitated by using a liquefied substrate as carbon source and inducer. Here, liquefied wheat bran (WB) was evaluated as carbon source and inducer in high-solids submerged cultivation (20\%, w/w) of a filamentous fungus, A. niger, for xylanase production. A systematic study (one factor at a time) of the use of liquefied WB under different conditions of temperature, pH, enzyme loading, and reaction time was performed. This study revealed that xylanase production was favored by a substrate liquefied using the optimum pH (4.8) and temperature conditions (50 degrees C) of the commercial enzymatic preparation (2.8 FPU/g solids), while the liquefaction time was not significant above 6 h. The proposed strategy resulted in xylanase activity 5-fold higher than for a cultivation with non-liquefied substrate (control). These findings should contribute to the development of xylanase production processes using high solids loading submerged cultivation in conventional large-scale bioreactors.
The paper covers the synthesis and characterization of cellulose derivatives from waste cellulose, namely, towel wastes. For this purpose, the cellulose acetate derivatives were synthesized from towel waste by applying the conventional chemical synthesis process. To clarify the structure of synthesized materials, some spectroscopic methods (FT-IR, XRD, H-1-NMR, C-13-NMR) were used. Furthermore, thermal behavior and surface morphology of prepared materials were investigated by DTG-TG and SEM, respectively. It was found that the degree of substitution values decreased as the duration of hydrolysis increased in cellulose diacetate synthesis. It was also understood that cellulose diacetate was dissolved in acetone differently from cellulose triacetate. Degree of substitution values of cellulose diacetate were compared by using H-1-NMR and titrimetric method. These helped elucidate the expected reaction. The proposed method was easy compared with the conventional method.
The use of coal fly ash (CFA) as raw material for the manufacture of two construction materials, fired clay bricks and silica-calcareous non-fired bricks, was investigated. Fired clay bricks were manufactured using a commercial clay and different waste ratios (0-50 wt\%), moulded at 10 MPa and fired at 1000 degrees C (4 h). Silica-calcareous non fired bricks were prepared using two wastes as raw material: CFA and ``geosilex{''
In this study, the pressures at 50-500 MPa were evaluated at different time to pretreat and further enzyme hydrolysis. The ultra-high pressure (UHP) pretreatment at 100 MPa for 10 min led to improved accessibility of enzyme for conversion of xylan to xylooligosaccharide (XOS). The maximum XOS yield of 35.6 mg/g substrate was achieved and firstly reported at 10\% (w/v) of substrate, 100 U of endo-xylanase/g corncobs and incubation time of 18 h. The enzymatic hydrolysis efficiency was increased by 180.3\% and released a high amount of xylobiose. The UHP pretreatment relatively did not affect to the composition of corncob, but decreased 34.3\% of lignin. Interestingly, antioxidant activities of XOS using UHP pretreatment were higher than untreated corncob. The UHP pretreatment improved lignocellulosic destructuration and XOS yields in a shorter time without the need of chemicals, implying that UHP could be an effective pretreatment of biomass with a chemical-free process. (C) 2017 Elsevier Ltd. All rights reserved.
A bibliometric analysis of the Scopus database was carried out to identify the research trends related to hemicellulose valorization from 2000 to 2016. The results from the analysis revealed an increasing number of annual publications, a high degree of transdisciplinary collaboration and prolific contributions by European researchers on this topic. The importance of a holistic approach to consider the simultaneous valorization of the three main components of lignocellulosic biomass (cellulose, hemicellulose and lignin) must be highlighted. Optimal pretreatment processes are critical for the correct fractionation of the biomass and the subsequent valorization. On the one hand, biological conversion of sugars derived from hemicellulose can be employed for the production of biofuel (ethanol) or chemicals such as 2,3-butadiene, xylitol and lactic acid. On the other hand, the chemical transformation of these sugars produces furfural, 5-hydroxyfurfural and levulinic acid, which must be considered very important starting blocks for the synthesis of organic derivatives.
NaOH pretreatment is one of leading technologies for pilot-scale production of cellulosic fuel ethanol. It has two obvious features: low-energy input which is good for its practical application and high wastewater generation which makes it cost too much to avoid environmental pollution. As the methods developed for solving pollution from wastewater, the effect of NaOH pretreatment on enhancing bioconversion of various feedstocks should be evaluated. This study investigated the influence of NaOH pretreatment on enzymatic hydrolysis of herbaceous biomass, softwood and hardwood based on their physico-chemical changes. After NaOH pretreatment, the lignin removal and changes in chemical groups and microstructure of herbaceous biomass were more obvious than those of softwood and hardwood. NaOH pretreatment had significant improvement on enzymatic hydrolysis of herbaceous biomass, and different NaOH-treated herbaceous lignocelluloses had different enzymatic hydrolysis efficiencies. NaOH pretreatment is more applicable for improving bioconversion of herbaceous biomass than softwood and hardwood.
In order to aggregate value to the grape stem (wastes), this research aim was to increase the adsorption capacity of Cd2+ by chemical modifications on grape stems. The grape stems were milled and sieved, resulting in the biosorbent, which was used for the chemical modifications resulting in E. H2O2, E. H2SO4 and E. NaOH. These were characterized by such means as its pH(pzc), Fourier transform-infrared (FTIR) spectroscopy, porosimetry, thermal stability and scanning electron microscopy. The ideal adsorption dose, the pH influence on adsorption, kinetics, equilibrium and thermodynamics studies were carried out. The FTIR spectroscopy suggests the occurrence of carboxyl, amine, and phenolic acting in Cd2+ sorption. The modification on grape biomass caused small increase in pore volume and specific surface area. The grape-based adsorbents have similar thermal stability, with irregular appearance and heterogeneity. 5.0 g kg(-1) is the best adsorption dose. The modified adsorbents exhibited increase in Cd2+ removal of 66\% for E. NaOH, 33\% for E. H2O2 and 8.3\% for E. H2SO4. The use of grape stem as adsorbent is an attractive alternative, because its wastes have great availability, low cost and great potential for metal adsorption processes.
Xylooligosaccharides (XOS) are emerging prebiotics which can be produced from lignocellulosic biomass including agro-residues and hardwood. In this study, we report the production of XOS from thermal alkali pretreated hardwood such as mahogany and mango by using a purified xylanase from Clostridium strain BOH3. In the first approach, pure xylan is extracted from mahogany and mango hardwood and then the pure xylan is hydrolyzed by using the xylanase. In this case, 572 and 504 mg XOS/g pure xylan were obtained from mahogany and mango woods, respectively. In the second approach, the same xylanase is employed to hydrolyze sawdust of hardwood after different types of pretreatments. After a thermal (121 degrees C for 15 min) pretreatment under a mild alkaline (0.05N NaOH) condition, the pretreated mahogany and mango sawdust can be utilized directly to produce 89.5 and 67.6 mg XOS/g pretreated sawdust, respectively. XOS produced from the pretreated sawdust show strong prebiotic effects on Bifidobacteria and Lactobacilli. This report shows the possibility of producing XOS from pretreated woody wastes without using pure xylan as a substrate. (C) 2017 Elsevier Ltd. All rights reserved.
This work validates a new strategy for complete utilization of palm residues by separating fibers and parenchyma for the respective purposes of pulping and biorefining. The parenchyma cells were fractionated from royal palm sheath (RPS) after neutral sulfite semichemical (NSSC) cooking for producing fermentable sugars, leaving vascular bundles for manufacturing pulp and paper. Parenchyma cells could be readily and completely screened out prior to defibration. They were more digestible by cellulase than vascular bundles or the pulp derived from them. Cellulose enzymatic digestibility (CED) of parenchyma cells rapidly reached 82\% in 12-h hydrolysis and finally up to 92\%. The CEDs of parenchyma were maintained around 90\% at a medium solid consistency, 12\% (w/w). The average length, retention and drainability of RPS pulp were all improved without loss of physical strength after removing parenchyma. This work may help establish a new platform for maximizing the utilization efficiency of parenchyma-rich biomass. (C) 2013 Elsevier Ltd. All rights reserved.
During the biomass pretreatment, the formation and repolymerization of lignin droplets on the surface of cell wall has a negative impact on the cellulose accessibility and enzymatic saccharification. When D. sinicus (DS) was treated with tetraethylammonium chloride/Oxalic acid-based deep eutectic solvent (TEAC/OA) at 120 degrees C and 7 h, the sodium carbonate and sodium hydroxide washing of pretreated residues decreased the surface lignin content by about 27 \% as compared to that cleaned with hot water, which can generate more cellulose accessible sites for enzymatic digestibility. Finally, the higher glucose yields of 70.69 \% for sodium carbonate washing and 76.25 \% for sodium hydroxide washing were achieved. This work provided an insight to overcome the negative effects of surface lignin and open a window for the efficient bamboo biorefinery of DES systems in southwest China.
Due to the production of industrial slags in massive amounts, there is a high demand for recycling these slags and avoiding their dumping in landfills. This article aims to recycle industrial slags in brick manufacturing and investigates the performance of fired clay bricks incorporating different kinds of industrial slags such as granulated blast furnace slag (GBS), ferrochromium slag (FCS), and steel slag (STS). For this purpose, two different dosages of slags (i.e., 10 and 20 wt \% of clay) and two different firing temperatures (i.e., 1000 and 1100 oC) were considered. Various physical, mechanical, and durability tests were performed to evaluate the properties of bricks incorporating industrial slags. Results show that the compressive strength of the bricks incorporating industrial slags are well above the minimum compressive strength limits of bricks as per different building standards. The bricks incorporating industrial slag can be classified as load-bearing bricks for structural applications in accordance with the ASTM C469 standard. An increase in the porosity of bricks is observed with the addition of STS. However, reduced porosity is observed for bricks incorporating FCS and GBS than traditional bricks. Based on the water absorption and efflorescence test results, bricks incorporating industrial slags can be used as severe weather resistant bricks following ASTM C62 standard and slight efflorescence bricks per ASTM C67 standard. The amounts of heavy metals in the leachates of bricks are observed below the specified limits of the Environment Protection Authority. SEM images and EDS analysis of bricks are also supporting the results of this study. Based on the results, utilizing industrial slags in brick manufacturing can help recycle the abundant industrial wastes and develop the fired clay bricks with desired properties.
We prepared polyamide-6 (PA-6) composites using bleached and semibleached cellulose fibers from Eucalyptus species by processing in a corotating interpenetrating twin-screw extruder. PA-6 is a challenging matrix because of its high processing temperature, which overlaps the thermodegradation temperature of the fibers. The selection of the processing conditions for extrusion and the use of the lubricant ethylene bis (stearamide) permitted the production of composites with 20, 30, and 40 wt\% of bleached fibers, which are lighter than the corresponding glass fiber composites. Composites with 30 wt\% of bleached fibers yield the best mechanical properties and good fiber/ matrix interaction, as demonstrated by mechanical tests and scanning electron microscopy. X-ray photoelectron spectroscopy studies showed that the natural moisture in the fibers promotes the fiber/ matrix interaction through the formation of ester bonds. We assessed the effect caused by the presence of lignin in the fibers. Composites containing 30 wt\% of semibleached fibers maintained the flexural properties and showed small improvements in thermal stability when compared with bleached fiber composites; however, there is a slight decrease in the tensile properties. Through accelerated aging tests, we observed that increased lignin concentration in the fibers reduced the formation of carbonyl compounds on sample surfaces, indicating a stabilization effect. (C) 2015 Society of Plastics Engineers
Steam explosion is a thermo-mechaticochemical Pretreatment which allows the breakdown oflighocellulosic structural components by the action of heating, formation of organic acids during the process, and shearing forces resulting in the,expansion of the moiSture. Two distinct stages,compose the steam explosion process: vapocracking and explosive decompression, which include modification of the material components: hydrolysis of hemitellulosic components (mono- and oligosaccharide released), modification of the chemical structure of lignin, and modification of the cellulose crystallinity index, etc. These effects allow the opening of lignocellulosic structures and influence the enzymatic hydrolysis yield of the material.
The increase in environmental consciousness has promoted the use of renewable resources. A tremendous spike has been observed in the use of products that decompose into environment-friendly constituents, which leads to the protection of the environment. Such environment-centric thinking has reduced the volume of solid waste generated by consumers every year, together with reuse and recycling. However, the environmentally friendly initiatives and regulations face a setback when the cost is high. Often the quality of such products is compromised in comparison with synthetically derived products for consumer usage. Plastic is a ubiquitous pollutant with potentially harmful effects on living beings. The increasing population and a steady increase in petrochemical plastics' demand hamper global plastic waste management. The use of bioplastics has helped us to overcome these issues. Poly(hydroxybutyrate) (PHB) is commonly known, first synthesized bioplastic, which has strong potential in replacing conventional plastics. This review focuses on the PHB biopolymer's significant properties over plastic, its application in different fields, i.e., medical science, agriculture, construction, packaging, energy, etc. It also covers PHB biosynthesis using different waste products as a substrate to minimize the production process cost, degradation, and different analytical methods to characterize the PHB. Along with these, we have also discussed about the other polysaccharide based biodegradable polymers.
Background: The prebiotic properties of fructooligosaccharides (FOS) are well documented. The high demand of functional food by the food, pharmaceutical and biotechnology industries have lead researchers to explore new and more feasible processes to produce FOS. Not only economical substrates are being exploited to reduce costs, but also, seeking to attend a global problem, the excessive generation of agro-industrial wastes that are polluting the earth, which are not being completely exploited, have been a concern. Scope and approach: The purpose of this review is to present a concise (but wide-ranging) appraisal on the latest advances in fructooligosaccharides production from agro-wastes, as alternative low-cost source. Emphasis is placed on the examination, analysis and discussion of the prospects for using different agro-industrial waste bioresources for the production of FOS and FOS-producing enzymes. Key findings and conclusions: The food, agro-industrial and forestry industries generate large volumes of waste, that are mainly composed of complex carbohydrates and crude proteins, that can be useful as nutrients for microbial growth, and enzymes or other metabolites production. Agro-industrial wastes are discarded, and its accumulation generates a severe environmental impact. The development of value-added processes using agroindustrial wastes is very attractive and becomes an environmentally friendly waste management method.
Lignocellulosic biomass is an attractive renewable resource to produce biofuel or platform chemicals. Efficient and cost-effective conversion systems of lignocellulosic biomass depend on their appropriate pretreatment processes. Alkali or dilute acid pretreatment of biomass requires a high temperature (>150 degrees C) to remove xylan (hemicellulosic sugar) and lignin partially. In this study, peracetic acid was used to pretreat biomass feedstocks, including hardwood and softwood species. It was found that the thermally-assisted dilute acid pretreatment of biomass conducted under the mild temperature of 90 degrees C up to 5 h resulted in the effective removal of lignin from the biomass with a negligible loss of carbohydrates. This thermally-assisted pretreatment achieved 90\% of delignification, and this result was compared with the microwave-assisted pretreatment method. In addition, the crystallinity index (CrI), surface morphology, and chemical structure were significantly changed after the acid pretreatment. The biomass digestibility increased significantly with increased reaction time, by 32\% and 23\% for hardwood and softwood, respectively. From this study, it is clear that peracetic acid pretreatment is an effective method to enrich glucan content in biomass by delignification.
Palm empty fruit bunches (EFBs) are abundant lignocellulosic wastes from palm oil mills. They are potential sources of sugars which can be converted to microbial lipids by oleaginous yeasts. To produce sugars from EFB, two-step and one-step hydrolysis reactions were performed. In the first step, the use of diluted sulfuric acid (0.5 \% w/v) hydrolyzed hemicelluloses and released mainly pentoses, and in the second step of hydrolysis of residual pulp using 2.5 \% (w/v), sulfuric acid released more hexoses. The use of 2.5 \% (w/v) sulfuric acid in one-step hydrolysis of holocelluloses released the highest amount of sugars (38.3 g/L), but it also produced high concentration of potential inhibitors (> 1 g/L). Three oleaginous yeasts, Rhodotorula mucilaginosa, Kluyveromyces marxianus, and Candida tropicalis, were isolated and screened for their ability to convert EFB hydrolysates into lipids. These yeasts grew well and produced lipids from EFB hemicellulose and holocellulose hydrolysate after potential inhibitors were removed. This study shows that EFB can be used for lipid production.
In the present study, the facile hydrothermal method is used to prepare sodium vanadate (Na5V12O32) nanowire arrays to act as adsorbents for removing cationic dyes. The samples are characterized and compared using scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrum, and X-ray diffraction. The adsorption quantity of methylene blue and gentian violet increases with the increase of adsorbent dose, adsorption time and initial dye concentration. Further, the adsorption kinetic and isotherm are well modeled by the Pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The rate control step is administered by means of intra-particle diffusion during the adsorption process. The maximum adsorption capacities of methylene blue and gentian violet are 1249.0 and 1079.7 mg g(-1), respectively. Additionally, the maximum dye removal rates for MB and GV are 85.32 \% and 84.46 \% after five cycles, respectively. As such, Na5V12O32 nanowire arrays can be used as an efficient, low-cost and recyclable adsorbent for cationic dyes removed from wastewater.
In the latest studies, the reuse, recycle, and recovery of various biomass wastes for high value-added bioproducts have received significant attention to reduce the environmental impact of fossil-based polymers. This review briefly describes various agricultural wastes used to extract cellulose nanocrystals (CNCs) and the pros and cons of common extraction methods. CNCs have been employed in high-performance materials due to their attractive properties such as lightweight, excellent mechanical strength, biocompatibility, biodegradability, renewability, high surface area, and tunable surface chemistry. Subsequent chemical modifications of CNCs allow it to serve in a wide range of applications: biocomposites, biomedical industry, food industry, cosmetics, wastewater treatments, and electronics industry. The challenges of CNCs production, the deficit in physicochemical properties and applications, and prospects of CNCs are discussed in detail in this review.
Poly(3-hydroxybutyrate) (PHB) has been proposed to be a potential candidate to be used as biomaterial. However, its poor processability, high brittleness and rigidity have limited its applicability. Transesterification reactions with poly(epsilon-caprolactone) (PCL), one of the most promising biomedical materials, emerge as an attractive alternative to improve its mechanical properties. In this work, poly(3-hydroxybutyrate-b-epsilon-caprolactone) (PHB-b-PCL) was prepared straightforwardly by transesterification of the parent homopolymers by reactive extrusion in the presence of stannous octanoate. After purification by solvent fractionation, PHB-b-PCL was characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy of carbon (C-13 NMR) and hydrogen (H-1 NMR) and, subsequently, submitted to electrospinning. The results indicate that PHB was modified, showing lower crystallinity as compared to the original homopolymers. The electrospun mats are tough and flexible and analysis by scanning electron microscopy indicates the formation of uniformly smooth morphology with average fiber diameter of 900-1200 nm and voids in the range between a few microns up to a few tens of microns, suitable for cell diffusion in biomedical applications.
Building bricks were produced by utilizing deinking paper mill sludge (DPMS) and alluvial soil by varying percentage of sludge at different firing temperatures. Different mix proportions were prepared with 0\%, 5\%, 10\%, 15\%, 20\%, 25\% and 30\% of DPMS incorporation in alluvial soil by weight. Three firing temperatures of 900 degrees C, 950 degrees C and 1000 degrees C were investigated to simulate the typical condition of kiln. The density, firing shrinkage, water absorption, efflorescence, apparent porosity, compressive strength and thermal conductivity of the bricks were determined. The XRD and microstructural analysis of brick specimens were also studied. The optimum firing temperature was 950 degrees C. The thermal conductivity decreases with increase in percentage of deinking paper mill sludge. It was found that 15\% deinking paper mill sludge gives optimum strength at firing temperature of 950 degrees C. Developed bricks satisfy the requirements of class 10 of Bureau of Indian Standards (BIS), in terms of efflorescence, compressive strength and water absorption. Thermal conductivity results show that the developed brick was thermally more insulated than the conventional bricks and can be used as alternative to conventional bricks. This will address the issue of waste management through cleaner production and show the ways towards sustainable, economical and energy efficient construction. (C) 2018 Elsevier Ltd. All rights reserved.
The successful isolation and characterization of water hyacinth fiber (Eichornia crassipes) (WHF) nanocellulose is presented in this study. The novelty was in exploring a wider range of properties of highly purified samples of WHF after each stage of production in more depth. The isolation was accomplished by pulping in a digester and sonication. Morphological changes before and after treatment were demonstrated by scanning electron microscopy (SEM). The lignin and hemicellulose content decreased during chemical treatment. Transmission electron microscopy (TEM) and particle size analyzer (PSA) were used to determine the morphology of WHF after sonication for 1 h. TEM shows that the diameter and length of nanocellulose WHF were 15.61 and 147.4 nm, respectively. The crystallinity index and crystalline domain area significantly increased after chemical treatment. The highest crystallinity index was 84.87 \% after an acid hydrolysis process. The increase in crystallinity leads to good thermal stability. Moisture absorption tests of WHF were carried out before and after treatment. The lowest moisture absorption was in the cellulose fiber after sonication (nanocellulose).
Biohydrogen production is a cheap and clean way to obtain hydrogen gas. In subtropical countries such as Brazil the average temperatures of 27 degrees C can favor the hydrogen producing bacteria growth. A mixed culture was obtained from a subtropical sludge treating brewery wastewater and anaerobic batch reactors were fed with glucose, sucrose, fructose and xylose in low concentrations (2.0, 5.0 and 10.0 g L-1) at 37 degrees C, initial pH 5.5 and headspace with N-2 (99\%) to maintain the anaerobic conditions. The inoculum was a subtropical granulated sludge from UASB (Upflow Anaerobic Sludge Blanket) reactor treating brewery wastewater. The higher H-2 yields were obtained in reactors operated with 2 and 5 g L-1 of fructose and they were 1.5 mol H-2 marl of fructose and 1.3 mol H-2 mol(-1) of sucrose, respectively. The volatile fatty acids (VFA) generated at the end of operation were, predominantly, butyric and acetic acid, indicating the favoring of the metabolic route of hydrogen generation by the consortium of anaerobic bacteria from the brewery wastewater. Biomolecular analyses revealed the predominance of hydrogen producing bacteria from Firmicutes phylum distributed in the families Streptococcaceae, Veillonellaceae and uncultured bacteria. These results confirm future applications of subtropical sludges with agroindustrial wastewaters containing low concentrations of sugars on hydrogen generation. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
This study investigated the quantitative and qualitative attributes of liquid product and biochar obtained from pyrolysis of woody biomass (rubberwood sawdust (RWS)) and non-woody biomasses (oil palm trunk (OPT) and oil palm fronds (OPF)). The prepared biomass was pyrolyzed at temperatures of 500 degrees C, 550 degrees C, and 600 degrees C by using an agitated bed pyrolysis reactor, and then the yields and characteristics of liquid product and biochar were determined. The results showed that liquid product and biochar yields were in the respective ranges of 35.94-54.40\% and 23.46-25.98\% (wt.). Pyrolysis of RWS at 550 degrees C provided the highest liquid yield. The energy content of the water free liquid product was in the range 12.19-22.32 MJ/kg. The liquid product had a low pH and it mainly contained phenol groups as indicated by GC-MS. The biochars had high carbon contents (75.07-82.02\%), while their oxygen contents were low (14.22-22\%). The higher heating value (HHV) of biochar was in the range 26.42-29.33 MJ/kg. XRF analysis revealed that inorganic elements had higher contents in biochar than in the original biomass. The slagging and fouling indexes of biochar were also different from those of the biomass. High carbon content of the biochar confirms potential for its use in carbon sequestration. The specific surface of biochar was lower than that of biomass, while the average pore diameter of biochar was larger than for raw biomass as revealed by BET and SEM. These results on liquid product and biochar obtained from RWS, OPT, and OPF demonstrate that they are promising feedstocks for biofuels and other value-added products.
Bioethanol is a promising substitute for fossil fuels to alleviate the energy crisis. To improve the economic and environmental efficiency of bioethanol production from lignocellulosic biomass, the recycling techniques related to pretreatment, enzymatic hydrolysis, fermentation and distillation are discussed in the present study. The core of recycling technique is to recycle wastes and high-cost additives, including pretreatment waste liquor, stillage, solid residues after hydrolysis and fermentation, cellulases and yeast. On the one hand, the waste liquor can be reused as fresh water for the same or different conversion steps; on the other hand, wastes are the potential feedstocks for by-products production. As for high-cost additives, the most common approach is collecting for the next batch conversion. After adoption of recycling techniques, the consumption of water, chemicals, cellulases and yeast is reduced, which directly saves the conversion cost of lignocellulosic bioethanol. Meanwhile, highvalue by-products and reduction of waste disposal indirectly increase economic and environmental efficiency. Besides, this review also provides the categories of wastes, influence factors of recycling, and the advantages and disadvantages of various recycling techniques. In order to resolve the drawbacks of toxics accumulation, low recycling efficiency and low economic feasibility in the existing recycling techniques, a novel recycling strategy that meets all-components utilization, non-wastes generation and high-cost additives recycling simultaneously is proposed. Moreover, the economic and environmental evaluation of recycling techniques on a pilot or industrial scale should be made more efforts in the future.
Anaerobic digestion (AD) is an efficient process for the conversion of predominantly organic waste into biogas. However, when those wastes have a lignocellulosic composition, the process is slower with low rates of biogas production potential. In these cases, the increment with other wastes, known as anaerobic codigestion (AcoD), proves to be effective, especially when animal waste is included. The objective of the study is to obtain the best waste proportion (manure/agricultural waste) according to the volume of biogas produced during the biodegradability test under investigation of the effects of different temperatures (from 36 to 60 degrees C). The preliminary investigation consisted of sampling and drying the wastes with analytical tests (TS, VS, COD, TOC, N, P, pH, and moisture), what did allow to determine the proportions to be used in the experimental research. The biodegradability test was evaluated in different proportions of substrate (banana leaf) and inoculum (bovine manure) (1:1; 1:2; 1:9; 0:1) under mesophilic and thermophilic conditions. During the test, different temperatures were tested, starting from 36 up to 60 degrees C, gradually increasing from 2 to 2 degrees C, every 3 or 5 days, to adapt the anaerobic microorganisms. The investigated proportions presented production different from biogas (in volume), which can be explained by the composition of the proportions and variability of proposed temperatures. The 1:9 proportion was that one which obtained the highest cumulative biogas yield among the proportions, with 113.00 mL/g VS. The results show that the tested AcoD has adaptability when undergone to the variation of temperature, with better profit of biogas in thermophilic temperatures, mainly for the proportion 1:9; when the best condition was considered for the profit of biogas for the employed wastes, in the conditions of the research.
With increasing population worldwide and the consumption of greenhouse gases (GHGs) emitting limited fossil fuel resources, the indispensable need of seeking sustainable energy sources and conversion methods have been realized that can offer possible alternative ways to substantially minimize biomass wastes and even pre-treatments assisted biorefinery systems to convert those wastes into biofuels and other bioproducts. Considerable attention, therefore, has been given to the generation of biofuels from lignocellulosic biomass including the agricultural wastes. Biochemical and biological methods for converting lignocellulosic biomass to biofuels are challenging because of their unreactive nature, and pre-treatments are the key for their successful and efficient conversions. This review explored, compared, and highlighted the significance of multi-stage pre-treatment over the single-step biorefinery systems for biofuels production from different sources. The multi-stage methods have exhibited to demand less energy consumption and reaction time, to enhance productivity of lignocellulose deconstruction. However, optimized and engineered multi-stage pre-treatment methods for multi-product biorefinery from specific feedstocks have not been fully investigated yet. The authors present the future research direction for potential industrial application of multi-stage pre-treatments with key technical considerations as well.
Ethanol production from food wastes does not only solve environmental issues but also provides renewable biofuels. This study investigated the feasibility of producing ethanol from food wastes at high solids content (35\%, w/w). A vacuum recovery system was developed and applied to remove ethanol from fermentation broth to reduce yeast ethanol inhibition. A high concentration of ethanol (144 g/L) was produced by the conventional fermentation of food waste without a vacuum recovery system. When the vacuum recovery is applied to the fermentation process, the ethanol concentration in the fermentation broth was controlled below 100 g/L, thus reducing yeast ethanol inhibition. At the end of the conventional fermentation, the residual glucose in the fermentation broth was 5.7 g/L, indicating incomplete utilization of glucose, while the vacuum fermentation allowed for complete utilization of glucose. The ethanol yield for the vacuum fermentation was found to be 358 g/kg of food waste (dry basis), higher than that for the conventional fermentation at 327 g/kg of food waste (dry basis).
The use of all sugars from biomass fractionation - that is, hexoses and pentoses - is essential to develop feasible processes in a biorefinery context. Hexoses are converted into different products by most microorganisms. The main issue is the conversion of pentoses, especially when mixed with hexoses. Improving sugar conversion in co-fermentation is a major challenge, which was explored in this work. Co-culture using Saccharomyces cerevisiae and evolved Kluyveromyces marxianus strains was evaluated by screening using 24 deep-well plates. Glucose depletion and 83\% of xylose conversion were achieved with supplemented hemicellulosic hydrolysate medium (medium volume corresponding to 2/5 of deep-well volume), and initial cell concentrations of 2.5 g L-1 for each yeast, incubated at 150 rpm. The screening strategy provided reliable data that confirmed the co-culture as a promising approach for the co-assimilation of biomass-derived sugars. The importance of aeration control for effective xylose assimilation was also pointed out.
This work described the morphologic changes of corn stalk and the structural characterization of its hemicelluloses dissolved in yellow liquor at different cooking stages. The results showed that active oxygen cooking process was an efficient method to depolymerize the corn stalk into cellulose, hemicelluloses, and lignin as a pretreatment of biomass conversion. This cooking process can also be divided into three phases: bulk delignification, extended delignification, and residual delignification. During the heating-up period 57.67\% of hemicelluloses and 62.31\% of lignin were removed from the raw material. However, only 15\% of hemicelluloses and 23.21\% of lignin were removed during at temperature' period. The hemicelluloses from the corn stalk and yellow liquor were composed of (1 -> 4)-beta-D-xylopyranose backbones substituted with alpha-L-arabinofuranosyl, 4-O-methyl-alpha-D-glucuronic acid, and some methoxyl residues. The backbones of hemicelluloses were gradually cleaved during the cooking process. The acetyl groups substituted with xylopyranosyl residues were completely cleaved during the cooking process. (C) 2014 Elsevier Ltd. All rights reserved.
The global environmental issue of arsenic (As) contamination in drinking water is a significant problem that requires attention. Therefore, the aim of this research was to address the application of a sustainable methodology for arsenic removal through mycoremediation aerated with micro-nanobubbles (MNBs), leading to bioscorodite (FeAsO4 center dot 2H(2)O) generation. To achieve this, the fungus Trichoderma atroviride was cultivated in a medium amended with 1 g/L of As(III) and 8.5 g/L of Fe(II) salts at 28 degrees C for 5 days in a tubular reactor equipped with an air MNBs diffuser (TR-MNBs). A control was performed using shaking flasks (SF) at 120 rpm. A reaction was conducted at 92 degrees C for 32 h for bioscorodite synthesis, followed by further characterization of crystals through Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray diffraction (XRD) analyses. At the end of the fungal growth in the TR-MNBs, the pH decreased to 2.7-3.0, and the oxidation-reduction potential (ORP) reached a value of 306 mV at 5 days. Arsenic decreased by 70\%, attributed to possible adsorption through rapid complexation of oxidized As(V) with the exchangeable ferrihydrite ((Fe(III)) (4-5)(OH,O)(12)), sites, and the fungal biomass. This mineral might be produced under oxidizing and acidic conditions, with a high iron concentration (As:Fe molar ratio = 0.14). The crystals produced in the reaction using the TR-MNBs culture broth and characterized by SEM, XRD, and FTIR revealed the morphology, pattern, and As-O-Fe vibration bands typical of bioscorodite and romerite (Fe(II)(Fe(III))(2)(SO4) 4 center dot 14H(2)O). Arsenic reduction in SF was 30\%, with slight characteristics of bioscorodite. Consequently, further research should include integrating the TR-MNBs system into a pilot plant for arsenic removal from contaminated water.
There is increasing attention to the production of cellulose nanocrystals (CNCs) from lignocellulosic biomass by enzymatic hydrolysis with cellulase. In this study, the feasibility of the application of a cellulase system from engineered strain Penicillium oxalicum cEES in the production of CNCs was assessed. Using commercial eucalyptus dissolving pulp (EDP) as substrate, the CNCs were successfully obtained by enzymatic hydrolysis with the cellulase cEES, and the total yields of CNCs reached 15.7\% through three-step enzymatic hydrolysis of total 72 h (24 h for each step). The prepared CNCs were characterized and found that their crystallinity and thermal stability were higher than that of EDP. In the later stage of enzymatic hydrolysis, the process efficiency of enzymatic preparation of CNCs greatly decreased because of the high crystallinity of cellulosic substrate, and a simple homogenization treatment can promote the enzymatic hydrolysis, as well as produce fusiform CNCs with more uniform size and more fermentable sugar that could be further converted into fuels and bulk chemicals through fermentation. This study provides a feasible enzymatic preparation process for CNCs with engineered cellulase and commercial cellulosic materials.
Recently, cellulose nanocrystals (CNCs) have attracted a significant interest in different fields including drug delivery, biomedical, and food applications. In this study, homogenization-ultrasonication as a non-hazardous, time-saving, and organic solvent free technique was applied for fabrication of CNCs from cotton linter, containing over 90\% cellulose. First, acid hydrolysis was applied on raw cellulose using sulfuric acid at 55, 60 and 65\% for 3, 5 and 7 min and at various homogenization speeds. Final CNCs were produced by ultrasonication (350 W) for 3 min. The physicochemical properties of CNCs, particle size, X-ray diffraction (XRD) pattern, Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), atomic force microscopy (AFM) and transmission electron microscopy (TEM) were studied. Production yield of CNCs was 59-72\%, and their water holding capacity was two times higher than raw cellulose. The average length of CNCs was 133 nm with a width of 10 nm and the XRD pattern revealed a 82\% crystallinity degree. The FTIR spectrum detected almost similar frequencies in the raw and crystalline cellulose, while intensity of CNC peaks was reduced. TEM results showed rod-like CNCs with a length of 229 nm. TGA results also showed that thermal stability of CNCs was reduced compared to raw cellulose. (C) 2019 Elsevier B.V. All rights reserved.
Xylitol is used as a natural sweetener in food products as well as a Source of energy in infusion therapy and in the prevention of otitis media, osteoporosis, lung infection and myoadenylate deaminase deficiency. Xylose may be reduced to xylitol by NADPH-linked xylose reductase (E.C.1.1.1.21) (XR), a beneficial economic alternative for the catalytic hydrogenation of pure xylose, obtained from lignocellulosic hydrolisates. The purpose of this work is to evaluate the bioconversion of xylose to xylitol using Purified XR and glucose 6-phosphate dehydrogenase as an auxiliary enzyme in order to reduce the cofactor NADP to NADPH required for the XR activity. For Such a purpose, cells were disrupted by sonication and the supernatant was diluted to 1:4. 1:5 and 1: 10 (v/v) for a further ultracentrifugation process using Amicon Ultra-15 Centrifugal Filter devices. The bioconversion of xylose into xylitol using both XR and G6PDH enzymes was done in a batch assay at room temperature. The partial purification yields of XR attained for 1:4, 1:5 and 1: 10 dilutions were respectively 45.6, 64.5 and 67.2\%. The use of both XR and G6PDH for the xylitol production reached a yield of 35.5\%.
This study assessed the feasibility of continuous hydrogen production in an anaerobic packed bed biofilm reactor (APBR) using paper mill effluent (PME) without any pretreatment or modification. To form a microbial biofilm on supports, the reactor was seeded with a thermal pretreated anaerobic sludge. After the start-up stage, under mesophilic conditions and pH control, the system performance in the case of hydrogen production as biofuel and VFAs as valuable by-products as well as COD removal was investigated at different hydraulic retention times (HRTs) (24, 16, 12, 8, 4, 2 and 1.2 h). The highest hydrogen concentration in the produced gas was 41.5 \% obtained at HRT 4 h. The highest hydrogen production rate and yield were 6.21 L H2 d- 1 L-1 at HRT 2 h and 0.96 mmol H2 g-1 COD at HRT 8 h, respectively. With decreasing the HRT from 24 to 1.2 h, the OLR was increased from 27.35 to 547 g COD L-1 d-1 that positively affect the hydrogen production rate for all HRTs except for the shortest HRT. Furthermore, COD removal efficiency was reduced from 25.2 to 6 \%. Low value of COD removal efficiency is because of conversion of organic inlet to valuable metabolites such as VFAs in the effluent.
The pertinent issue of resources shortage arising from global climate change in the recent years has accentuated the importance of materials that are environmentally friendly. Despite the merits of current material like cellulose as the most abundant natural polysaccharide on earth, the incorporation of lignocellulosic biomass has the potential to value-add the recent development of cellulose-derivatives in drug delivery systems. Lignocellulosic biomass, with a hierarchical structure is comprised of cellulose, hemicellulose and lignin. As an excellent substrate that is renewable, biodegradable, biocompatible and chemically accessible for modified materials, lignocellulosic biomass sets forth a myriad of applications. To date, materials derived from lignocellulosic biomass have been extensively explored for new technological development and applications, such as biomedical, green electronics and energy products. In this review, chemical constituents of lignocellulosic biomass are first discussed before we critically examine the potential alternatives in the field of biomedical application. In addition, the pretreatment methods for extracting cellulose, hemicellulose and lignin from lignocellulosic biomass as well as their biological applications including drug delivery, biosensor, tissue engineering etc. are reviewed. It is anticipated there will be an increasing interest and research findings in cellulose, hemicellulose and lignin from natural resources, which help provide important directions for the development in biomedical applications.
Environmental pollution, particularly from heavy metal ions in the wastewater, is one of the most serious concerns of the world. In the pursuit of remedial action, various conventional methods such as ion exchange, chemical precipitation, coagulation, membrane separation, reverse osmosis, and adsorption methods have so far been used for the removal of heavy metal ions. A good variety of adsorbents have been developed to remove different heavy metal ions from wastewater in particular those which have been detrimental to living organisms. Adsorption processes have been very demanding for high removal efficiency of heavy metal ions even at trace levels and they are low cost as compared to conventional methods. It has therefore been crucial to develop low cost and readily available adsorbents for the adsorption of heavy metal ions from wastewater. The adsorbents may be collected from agricultural and animal waste and industrial by-products. All adsorbents, by their intrinsic nature, have functional groups to play the key role in metal ion adsorption. Generally, chemically modified adsorbents enhance the surface area of the adsorbent and exhibit higher adsorption capacity than unmodified adsorbents. In this review, a series of natural waste materials and their modified forms have been evaluated for the removal of various metals from potable and wastewater. The major focus has been an accumulation of comprehensive knowledge on of the use of the low-cost adsorbents for removal of heavy metal ions.
Enhancing the swelling of chemithermomechanical pulp is essential for improving its physical properties and thus broadening its end-use applications. In this work, ionic liquid (IL) using 1-allyl-3-metheylimidazolium chloride ({[
The acylation modification of cellulose to make it processable is an important method to utilize this green, renewable material with broad prospects. However, it usually takes several hours or even more than 20 h to obtain products with a high degree of substitution (DS) through the methods reported in the existing literature, especially for cellulose acetate (CA). In this study, rapid homogeneous acylation of cellulose is achieved in a novel CO2 switchable solvent system by using microwave heating. CA products with DS ranging from 1.83 to 2.91 can be obtained within 3-15 min by using acetic anhydride as the acylation reagent. This strategy can also be applied for the synthesis of a series of cellulose esters with different side chain lengths, and it takes only 10 min to produce cellulose esters with a DS higher than 2.20 under microwave heating. This study suggests a facile and effective method for the synthesis of cellulose esters.
This study aims to extract and characterize cellulose nanocrystals (CNCs) from date pits (DP), an agricultural solid waste. Two methods were used and optimized for the cellulose nanocrystals (CNCs) extraction, namely the mechanical stirrer method (CNCs1) and the Soxhlet apparatus method (CNCs2) in terms of chemical used, cost, and energy consumption. The results showed that scanning electron microscopy revealed the difference in the morphology as they exhibit rough surfaces with irregular morphologies due to the strong chemical treatments during the delignification and bleaching process. Moreover, transmission electron microscopy analysis for CNCs reveals the true modification that was made through sulfuric acid hydrolysis as it presents cellulose microfibrils with a packed structure. Fourier transform infrared proved that the CNCs were successfully extracted using the two methods since most of the lignin and hemicellulose components were removed. The crystallinity index of CNCs1 and CNCs2 was 69.99\%, and 67.79\%, respectively, and both presented a high yield of CNCs (>10\%). Ultimately, both techniques were successful at extracting CNCs. Based on their cost-effectiveness and time consumption, it was concluded that method 1 was less expensive than method 2 based on the breakdown of the cost of each step for CNCs production. (c) 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Lignin dissolution in dialkylimidazolium-based ionic liquid (IL)-water mixtures (40 wt\%-100 wt\% IL content) at 60 degrees C was investigated. The IL content and type are found to considerably affect lignin solubility. For the IL-water mixtures except 1-butyl-3-methylimidazolium tetrafluoroborate ({[
This study investigated the production of ethanol from unutilized branches pruned from pear trees by steam explosion pretreatment. Steam pressures of 25, 35, and 45 atm were applied for 5 min, followed by enzymatic saccharification of the extracted residues with cellulase (Cellic CTec2). High glucose recoveries, of 93.3, 99.7, and 87.1\%, of the total sugar derived from the cellulose were obtained from water- and methanol-extracted residues after steam explosion at 25, 35, and 45 atm, respectively. These values corresponded to 34.9, 34.3, and 27.1 g of glucose per 100 g of dry steam-exploded branches. Simultaneous saccharification and fermentation experiments were done on water-extracted residues and water- and methanol-extracted residues by Kluyveromyces marxianus NBRC 1777. An overall highest theoretical ethanol yield of 76\% of the total sugar derived from cellulose was achieved when 100 g/L of water- and methanol-washed residues from 35 atm-exploded pear branches was used as substrate.
Biorefineries integrate processes for the sustainable conversion of biomass into chemicals, materials, and bio-energy so that resources are optimized and effluents are minimized. Despite the vast potential of lignocellulosic biorefineries, their success depends heavily on effective, economically viable, and sustainable biomass frac -tionation. Although efficient, organosolv pretreatment still faces challenges that must be overcome for its widespread utilization, mainly related to solvent type and recycling, robustness regarding biomass type and integration of hemicellulose recovery and use. This review shows the recent advances and state-of-the-art of organosolv pretreatment, discussing the advances, such as the use of biobased solvents, whilst also shedding light on the perspectives of using the streams - cellulose, hemicellulose, and lignin - to produce biofuels and products of high added value. In addition, it presents an overview of the existing industrial implementations of organosolv processes and, lastly, shows the main scientific and industrial challenges and opportunities for this process.
The objective of this study was to characterise and evaluate a wild inedible cassava species, Manihot glaziovii as feedstock for bioenergy production. Tubers obtained from 3 different areas in Tanzania were characterised and evaluated for bioethanol and biogas production. These bioenergy carriers were produced both separately and sequentially and their energy values evaluated based on these two approaches. Composition analysis demonstrated that M. glaziovii is a suitable feedstock for both bioethanol and biogas production. Starch content ranged from 77\% to 81\%, structural carbohydrates 3-16\%, total crude protein ranged from 2\% to 8\%. Yeast fermentation achieved ethanol concentration of up to 85 g/L at a fermentation efficiency of 89\%. The fuel energy of the bioethanol and methane from flour-peels mix ranged from 5 to 13 and 11 to 14 MJ/kg VS, respectively. Co-production of bioethanol and biogas in which the peels were added to the fermentation residue prior to anaerobic digestion produced maximum fuel energy yield of (15-23 MJ/kg VS). (C) 2014 Elsevier Ltd. All rights reserved.
Hydrothermal dissolution and/or conversion of cellulose Avicel (R) occurred at 190 degrees C under 5 MPa of H-2 in the absence of catalyst. This reaction is temperature and time dependent. A dissolution-conversion ratio of 35\% was obtained after 24 h of reaction and glucose and HMF were detected as monomeric products in a global yield of less than 5\%, indicating that the majority of the products are composed of soluble oligo-and polysaccharides. The unreacted cellulose was analyzed using XRD, C-13 solid state NMR, TGA-DTA and SEM and compared to the initial cellulose. We showed that although morphology changes occurred during the reaction, no modification of the crystallinity was observed and that hydrothermal treatment did not affect a specific part of the cellulose polymer. The presence of Pt/gamma-Al2O3 increased the initial rate of dissolution-conversion significantly as well as the distribution of the monomeric products. Pt and H-2 atmosphere were seen to increase the dissolution-conversion ratio however their role has not been yet well established.
Which factors are crucial to improving lignin antioxidant ability in polymers has been debated over years. Here, the structural effect of natural antioxidant from technical Kraft lignin (KL) on the oxidation induction time (OIT) of KL/polypropylene (PP) was quantitatively investigated using correlation analysis model instead of traditional linear fitting model. The correlation coefficient and significance value of their relationship clearly demonstrated the dominating role of non-condensed Phenolic -OH (Ph-OH) in improving KL/PP thermal-oxidation stability, subsequently followed by (M)over bar(n), aliphatic -OH/total Ph-OH, condensed Ph-OH and polydispersity. OIT is positive with non-condensed and total Ph-OH, while it declines with increase of the above other factors. Remarkably, the longest OIT (similar to 90 min) was obtained even at extreme loading (0.5 wt\%), almost similar to 911\% and similar to 201\% huge increase in contrast to that of pure PP and crude KL/PP composite, respectively. Meanwhile, the mechanical properties of KL fractions/PP blends can be maintained at the same or better level than that of pure PP, due to strong interfacial adhesion strength. (C) 2017 Elsevier B.V. All rights reserved.
To reduce the cost of pretreatment, an advanced formic acid pretreatment directly using spent liquor was developed for corn cob valorisation in this work. The spent liquor pretreatment showed a satisfactory lignocellulose fractionation effect, and a high enzymatic hydrolysis efficiency over 95\% was achieved even when the spent liquor was recycled 5 times. Based on this result, the direct recycling of the spent liquor for pretreatment could lead to a threefold increase in the amount of corn cob processed and reduce energy consumption on the recovery unit by 80\%. Meanwhile, the recycling strategy of spent liquor also could bring an enrichment of xylooligosaccharides (XOS) in the spent liquor. A total of 56.0 g/L XOS was obtained with a high proportion of XOS in spent liquor, which favoured XOS separation and purification during the downstream process of XOS production. The developed strategy shows a good potential on the industrialization of formic acid pretreatment for biorefineries.
Lignin is the most abundant aromatic compound in natural world and usually produced as a by-product in pulping industry and biomass biorefinery. To achieve direct and efficient conversion of lignin to electricity, we have constructed an electron transport chain mediated by several redox couples including {[
Lignin is considered as a promising substitute for fossil resources, but its efficient conversion remains a huge challenge due to the structural complexity and immiscibility with typical solvents. Herein, a series of surfactant-free microemulsion reactors comprised of n-octane, water and n-propanol were designed and their corresponding phase behaviors alongside their ability to intensify oxidative depolymerization of lignin were explored. Experimental results show that the phenolic monomer yield improves substantially (40-500 wt\%) by comparison with processes performed in a single solvent. Detailed characterizations also suggest that the above intensification is rationalized by the solubilization effect of microemulsion system and directional aggregation of lignin at the microemulsion interface.
Cellulose has been extracted from a wide range of land resources, whereas it has been scarcely exploited from marine resources. Cellulose from green seaweeds can be extracted together with smaller molecules called ulvans. We have successfully extracted and characterized cellulose from Ulva sp. Solid state C-13 NMR indicated the presence of ulvans in the cellulose extracts. The extracted cellulose was blended with polylactide and polydioxanone and electmspun into nanofibrous mats with a range of physico-chemical properties. These cellulosebased scaffolds were assessed in vitro using fibroblast cells and showed accelerated cell growth. In vivo biocompatibility studies using a Wistar rat model indicated the absence of foreign body response and enhanced angiogenesis.
Experiments and calculations are used to determine the optimum parameters of the peroxide delignification of larch wood in the presence of MnSO(4)catalyst that provides high yields of cellulose (44.3 wt \%) with low residual lignin contents at a temperature of 100 degrees C, an H(2)O(2)content of 6 wt \%, a CH3COOH content of 25 wt \%, a LWR of 15, and a duration of 3 h The cellulose obtained under optimum conditions has a chemical composition of cellulose, 92.7 wt \%; lignin, 0.6 wt \%; and hemicellulose, 5.7 wt \%. IRS and X-ray diffraction are used to determine that cellulose obtained from larch wood has a structure similar to that of industrial microcrystalline cellulose. The proposed catalytic approach allows cellulose to be obtained from larch wood with a minimal lignin content under mild conditions in one step and with a high yield, a degree of crystallinity of 0.8, and a crystallite size of 3.0 nm.
Cellulose nanocrystals (CNCs) have attracted increasing attention in the field of nanomaterials because of its high aspect ratio, good structure, and high thermal stability. In this study, enzymatic hydrolysis-assisted high-pressure homogenization was applied as an environmentally friendly technique to extract CNCs from cotton-derived microcrystalline cellulose (MCC). The overall optimization of enzymatic pretreatment was conducted by response surface methodology, and the maximum CNCs yield was 40.09\% under the optimized experimental conditions. The extracted CNCs under the optimal conditions showed needle-like shape with a length of 100-250 nm and a width of 5-10 nm and exhibited an overall particle size range of 3-80 nm. The basic chemical structure of cellulose was not changed after enzymatic hydrolysis and high-pressure homogenization. The CNCs exhibited slightly lower crystallinity and higher thermal stability than MCC. High aspect ratio CNCs extracted in this present study have great potential as a reinforcing agent in biodegradable packaging materials.
Wet torrefaction emerges as a potential biomass pretreatment process to enhance the fuel properties of biomass. The present research was aimed to determine the energy-efficient conditions for the wet torrefaction of palm kernel shell via response surface methodology. The inherent relationship between fuel properties and operating conditions such as temperature (180-220 degrees C), residence time (10-30 min), and the palm kernel shell (PKS)/water ratio (0.1:0.2) was investigated, and temperature was observed to be the most significant parameter. Higher heating value of PKS was increased from 18.9 to 23.4 MJ/kg after torrifying at 220 degrees C, 30 min, and a water-to-biomass ratio at 0.2. The outcome of thermal analysis confirmed that wet-torrefied PKS exhibited an improved combustion behavior. The highest value of the comprehensive performance index for torrefied PKS was 5.687 x 10(-10) min(-2) C-3. Wet torrefaction improved the fuel properties of PKS as the torrefied biomass had a higher carbon content, lower oxygen content, and lower ash content than raw PKS.
An effective method for corncob saccharification was investigated over a magnetic carbon-based solid acid (MMCSA) catalyst in the aqueous phase. MMCSA was synthesized through a simple and inexpensive impregnation-carbonization-sulfonation process. Under the optimal reaction conditions (150 degrees C, 2 h, 0.5 g corncob, 0.5 g catalyst and 50 ml deionized water), 74.9\% of xylose yield was directly obtained from corncob, with 91.7\% cellulose retention in the residue. After the reaction, the MMCSA was easily separated from the residue using an external magnet and reused 4 times, showing its high stability and catalytic activity. The enzymatic digestibility of the pretreated residue reached 95.2\%, with a total sugar yield of 90.4\%. The morphological and structural properties of the natural and treated corncobs were analyzed primarily through 3D X-ray microscopy to characterize the cell wall thickness, porosity, and pore surface area distribution. The increase of macropores (pore surface areas >200 m(2)) was beneficial for the accessibility of cellulose to cellulosic enzymes, so the enzymatic digestibility was enhanced immediately. Compared with other traditional hydrolysis methods, this two-step hydrolysis approach represents an environmentally friendly and sustainable saccharification of lignocellulose to produce xylose and glucose while achieving the same level of reaction efficiency.
Elephant grass was subjected to steam explosion to enhance cellulose accessibility and convert it into ethanol. After catalyzed pretreatment at 190 degrees C for 5 min, enzymatic hydrolysis was carried out using high rate of solid loading combined with different enzyme dosages. Assays employing 20\% (w/v) solids loading and an enzyme dosage of 20 FPU g(-1) substrate led to a yield of 86.02 g glucose released per 100 g potential glucose in the water insoluble solids. This condition was selected to carry out the simultaneous saccharification and fermentation procedure through S. cerevisiae CAT-1, producing 42.25 g L-1 ethanol with a yield of 74.57\% regard to the maximum theoretical. The liquor containing C5 and C6-sugars was successfully converted into lactic acid using L. buchneri NRRL B-30929, resulting in 13.35 g L-1 with a yield of 68.21\% in relation to the maximum theoretical.
The different physical and chemical properties of lignin might have various effects on the enzymatic hydrolysis of lignocellulosic substrates. In this study, the influence of lignin on enzymatic digestibility of cellulose was assessed. Addition of 20\% (4g/L) isolated enzymatic lignin (lignin 2 and 3) and kraft lignin (lignin 4) resulted in 5-20\% drop of glucose yield, depending on lignin sources. The inhibitory effect of lignin was abated as the enzyme loading increased from 10 to 20 FPU/g dry substrate. However, the increasing lignin amount to 40\% (8 g/L) did not appear to further decrease the cellulose hydrolysis efficiency. Ethanol lignin (lignin 1) and calcium lignosulfonate (lignin 5) had no negative effect on the enzymatic hydrolysis of cellulose at cellulase loading of 10 or 20 FPU/g dry substrate, the increasing lignin content to 40\% presented 6.2\% increase of glucose yield. The results indicated that different lignin had significantly influence on the enzymatic hydrolysis, which was confirmed by analysis in chemical composition, elemental analysis, functionality, and thermogravimetry. (C) 2017 Elsevier Inc. All rights reserved.
Nanocellulose was successfully isolated from Gelidium elegans red algae marine biomass. The red algae fiber was treated in three stages namely alkalization, bleaching treatment and acid hydrolysis treatment. Morphological analysis was performed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). TEM results revealed that the isolated nanocellulose had the average diameter and length of 21.8 +/- 11.1 nm and of 547.3 +/- 23.7 nm, respectively. Fourier transform infrared (FTIR) spectroscopy proved that the non-cellulosic polysaccharides components were progressively removed during the chemically treatment, and the final derived materials composed of cellulose parent molecular structure. X-ray diffraction (XRD) study showed that the crystallinity of yielded product had been improved after each successive treatments subjected to the treated fiber. The prepared nano dimensional cellulose demonstrated a network-like structure with higher crystallinity (73\%) than that of untreated fiber (33\%), and possessed of good thermal stability which is suitable for nanocomposite material. (C) 2016 Elsevier Ltd. All rights reserved.
Lignocellulosic materials are among the most promising alternative energy resources that can be utilized to produce cellulosic ethanol. However, the physical and chemical structure of lignocellulosic materials forms strong native recalcitrance and results in relatively low yield of ethanol from raw lignocellulosic materials. An appropriate pretreatment method is required to overcome this recalcitrance. For decades various pretreatment processes have been developed to improve the digestibility of lignocellulosic biomass. Each pretreatment process has a different specificity on altering the physical and chemical structure of lignocellulosic materials. In this paper, the chemical structure of lignocellulosic biomass and factors likely affect the digestibility of lignocellulosic materials are discussed, and then an overview about the most important pretreatment processes available are provided. In particular, the combined pretreatment strategies are reviewed for improving the enzymatic hydrolysis of lignocellulose and realizing the comprehensive utilization of lignocellulosic materials. (C) 2015 Elsevier Ltd. All rights reserved.
Homogeneous esterification of cellulose isolated from Stipa tenacissima plant located in the eastern region of Morocco, using anhydride and acid chloride compounds has been performed in ionic liquids (ILs) prepared in our laboratory as reaction mediums. ILs were chosen as solvents due to their green character and ability to disperse native cellulose compared to other solvents. {[
Aspergillus fumigatus R1, on submerged fermentation using agricultural residues as carbon source produced extracellular xylanase (152 IU/ml after 96 h of incubation at 37 degrees C with constant shaking at 100 rpm). A maximum yield of 1 gm\% Xylooligosaccharides (XOS) mixture was obtained after 12 h by enzymatic hydrolysis of xylan rich wheat husk without any prior pretreatment using the crude enzyme without any purification. HP-TLC data confirmed the presence of an array of XOS for its prebiotic properties by carrying out studies on ten standard probiotic cultures. Six of ten probiotic cultures were able to utilize XOS produced from agricultural wastes and showed remarkable growth in the media containing XOS as the sole source of carbon. XOS mixture also exhibited concentration dependent anti-oxidant activity. Thus, the results showed that XOS produced from agricultural residues have great prebiotic potential and good antioxidant activity; therefore, it can be used in food-related applications.
Hydrothermal treatment is an environmentally friendly technology that allows the solubilisation of hemicellulosic oligosaccharides with potential for their use as prebiotics. The purpose of this study was to solubilize oligosaccharides and antioxidant compounds from chestnut shells by a hydrothermal processing. The highest content of oligosaccharides (18.3 g/L), with a relatively low level of monosaccharides (2.4 g/L) and degradation products (0.5 g/L) was obtained at 180 degrees C (severity of 3.08). In addition, the liquors presented a high content of phenolic and flavonoid compounds with good antioxidant properties. The GC-MS revealed that the most abundant phenolic compound was pyrogallol (13.2\%). The molecular weight distribution of the solubilization products showed that a 26.5\% presented an apparent Mw of 6077 g/mol and a 73.5\% presented an apparent Mw of 586 g/mol with a high polydispersity index. MALDI-TOF, FTIR, and TGA analyses revealed structural information of these compounds and their thermal stability.
One of the main challenges for the 21st century is to balance the increasing demand for high-quality proteins while mitigating environmental impacts. In particular, cropland-based production of protein-rich animal feed for livestock rearing results in large-scale agricultural land-expansion, nitrogen pollution, and greenhouse gas emissions. Here we propose and analyze the long-term potential of alternative animal feed supply routes based on industrial production of microbial proteins (MP). Our analysis reveals that by 2050, MP can replace, depending on socioeconomic development and MP production pathways, between 10-19\% of conventional crop-based animal feed protein demand. As a result, global cropland area, global nitrogen losses from croplands and agricultural greenhouse gas emissions can be decreased by 6\% (0-13\%), 8\% (-3-8\%), and 7\% (-6-9\%), respectively. Interestingly, the technology to industrially produce implementation and has the potential to cause a major structural change MP at competitive costs is directly accessible for in the agro-food system.
Every year, considerable amount of pistachio by-products is generated in pistachio processing industry which their disposal is an important challenge. Our study aimed to produce valuable prebiotic xylooligosaccharides (XOS) from pistachio shell (PS) that have no particular uses. Alkaline hydrogen peroxide application yielded 32.85\% xylan with low residual lignin content (2.48\%). Structural characterization of mentioned xylan determined. Enzymatic hydrolysis of xylan with commercial endoxylanase afforded breakdown into XOS containing xylobiose and xylotriose. Response surface methodology (RSM) disclosed the optimized condition as: enzyme dose of 85 (U/g), the concentration of substrate (6\%) and the reaction time (10 h) corresponding to maximum yield of xylobiose (1.86 mg/ml) and xylotriose (0.818 mg/ml). Application of the two-step process consisting of xylan extraction pursued by enzymatic hydrolysis enabled prebiotic XOS production for food and pharmaceutical industrial uses, from the pistachio shell as a novel raw material.
This work aims to evaluate the impact of microwave-assisted methodology in the pretreatments of the eucalyptus waste (Eucalyptus citriodora), to remove non-cellulosic components. Two pretreatments, without and with microwave, were used: (a) mercerization using sodium hydroxide, and (b) bleaching using hydrogen peroxide. The times (15 and 30 min) and power (100 W, 400 W, and 800 W) of microwave varied in order to find out the best conditions to obtain cellulose fibers. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy, thermogravimetric analysis (TGA), lignocellulosic contents (TAPPI), and statistical analysis (bivariate analysis) were used to evaluate the delignification of the obtained cellulose fibers. Life Cycle Impact Assessment (LCIA) analyses were used to evaluate environmental impacts {[
Many approaches have been considered aimed at ethanol production from the hemicellulosic fraction of biomass. However, the industrial implementation of this process has been hindered by some bottlenecks, one of the most important being the ease of contamination of the bioreactor by bacteria that metabolize xylose. This work focuses on overcoming this problem through the fermentation of xylulose (the xylose isomer) by native Saccharomyces cerevisiae using xylo-oligomers as substrate. A new concept of biocatalyst is proposed, containing xylanases and xylose isomerase (XI) covalently immobilized on chitosan, and co-encapsulated with industrial baker's yeast in Ca-alginate gel spherical particles. Xylo-oligomers are hydrolyzed, xylose is isomerized, and finally xylulose is fermented to ethanol, all taking place simultaneously, in a process called simultaneous hydrolysis, isomerization, and fermentation (SHIF). Among several tested xylanases, Multifect CX XL A03139 was selected to compose the biocatalyst bead. Influences of pH, Ca2+, and Mg2+ concentrations on the isomerization step were assessed. Experiments of SHIF using birchwood xylan resulted in an ethanol yield of 0.39 g/g, (76\% of the theoretical), selectivity of 3.12 g(ethanol)/g(xylitol), and ethanol productivity of 0.26 g/L/h.
The self-sustaining nature of renewable energies makes it necessary to continuously search for substrates that satisfy a growing interest in the production of biofuels, taking care of areas such as food security. In this work we optimized a hydrolysis process of Opuntia ficus-indica cladodes using acid diluted and surface response methodology. The nopal is a secondary crop widely distributed in arid and semi-arid zones and recently investigated for its potential in the biofuel industry given its versatility as a crop. The result of this optimization was the production of 20,825 mg mL(-1) of total reducing sugars (TRS), at 27.25 minutes of reaction and with a solution of 3.46\% sulfuric acid. The main sugars obtained in the hydrolyzed were galactose (57.14\%), arabinose (20.51\%), glucose (13.18\%) and xylose (9.17\%). Also, it emphasizes the value of humidity of this culture (90\%) and the low amount of lignin present (2.70\%).
Pre-treatment of biomass is a necessary step for delignification as well as an unavoidable step in the journey of biomass to biofuel. Apart from delignification, defragmentation and partial depolymerization of biomass are two other additional useful steps in the overall process of pre-treatment. Ultimately these three steps together make the downstream enzymatic hydrolysis process more effective in producing optimum total reducing sugar. Several different pre-treatment technologies are available to delignify various types of biomasses with each of them being unique concerning specific advantages and disadvantages, characteristics of its own. However, different pre-treatment methods, in combination, have been found beneficial with higher delignification efficiency in comparison to a single pre-treatment method, implemented on its own. Apart from physical pre-treatment procedures like milling, grinding, steam explosion, etc., pre-treatment methods can be divided, roughly, into three groups: biological pre-treatment, physical pre-treatment and chemical pre-treatment. Chemical pre-treatments always arrest significantly higher attention due to their effectiveness and minimum treatment time required. In this review, a thorough discussion of various chemical and biological pre-treatment technologies, along with their efficacy and effective outcomes, have been discussed in order to understand their impacts on bioenergy industries.
To meet the worldwide rapid growth of industrialization and population, the demand for the production of bioethanol as an alternative green biofuel is gaining significant prominence. The bioethanol production process is still considered one of the largest energy-consuming processes and is challenging due to the limited effectiveness of conventional pretreatment processes, saccharification processes, and extreme use of electricity in common fermentation and purification processes. Thus, it became necessary to improve the bioethanol production process through reduced energy requirements. Membrane-based separation technologies have already gained attention due to their reduced energy requirements, investment in lower labor costs, lower space requirements, and wide flexibility in operations. For the selective conversion of biomasses to bioethanol, membrane bioreactors are specifically well suited. Advanced membrane-integrated processes can effectively contribute to different stages of bioethanol production processes, including enzymatic saccharification, concentrating feed solutions for fermentation, improving pretreatment processes, and finally purification processes. Advanced membrane-integrated simultaneous saccharification, filtration, and fermentation strategies consisting of ultrafiltration-based enzyme recycle system with nanofiltration-based high-density cell recycle fermentation system or the combination of high-density cell recycle fermentation system with membrane pervaporation or distillation can definitely contribute to the development of the most efficient and economically sustainable second-generation bioethanol production process.
Pineapple materials sourced from agricultural waste have been employed to process novel bio-degradable rigid composite foams. The matrix for the foam consisted of starch extracted from pineapple stem, known for its high amylose content, while the filler comprised non-fibrous cellulosic materials sourced from pineapple leaf. In contrast to traditional methods that involve preparing a batter, this study adopted a unique approach where the starch gel containing glycerol were first formed using a household microwave oven, followed by blending the filler into the gel using a two-roll mill. The resulting mixture was then foamed at 160 \& DEG;C using a compression molding machine. The foams displayed densities ranging from 0.43-0.51 g/cm(3) and exhibited a highly amorphous structure. Notably, the foams demonstrated an equilibrium moisture content of approximately 8-10\% and the ability to absorb 150-200\% of their own weight without disintegration. Flexural strengths ranged from 1.5-4.5 MPa, varying with the filler and glycerol contents. Biodegradability tests using a soil burial method revealed complete disintegration of the foam into particles measuring 1 mm or smaller within 15 days. Moreover, to showcase practical applications, an environmentally friendly single-use foam tray was fabricated. This novel method, involving gel formation followed by filler blending, sets it apart from previous works. The findings highlight the potential of pineapple waste materials for producing sustainable bio-degradable foams with desirable properties and contribute to the field of sustainable materials.
Endophytic fungi in plant tissues produce a wide range of secondary metabolites and enzymes, which exhibit a variety of biological activities. In the present study, litter endophytic fungi were isolated from a fire-prone forest and screened for thermostable cellulases. Among nine endophytic fungi tested, two isolates, Bartalinia pondoensis and Phoma sp., showed the maximum cellulase activity. Bartalinia pondoensis was further selected for its cellulase production and characterization. Among the carbon and nitrogen sources tested, maximum cellulase production was observed with maltose and yeast extract, and the eucalyptus leaves and rice bran served as the best natural substrates. The cellulase activity increased with increasing temperature, with maximum activity recorded at 100 degrees C. The maximum CMCase activity was observed between pH 6.0 and 7.0 and retained 80\% of its activity in the pH range of 8-10. Partially purified cellulase of B. pondoensis retained 50\% of its activity after 2 h of incubation at 60 degrees C, 80 degrees C and 100 degrees C. These results suggest that litter endophytic fungus B. pondoensis is a potential source for the production of thermostable and alkali-tolerant cellulase.
The objective of the present work was to evaluate the use of Raman microspectroscopy analysis to assess changes in cellulose micro/nanofibril structure from fibers subjected to different pre-treatments. Pulp fibers were pre-treated with 5 wt\% NaOH for 2 h, 10 wt\% NaOH for 1 h, and endoglucanase-type enzymes to improve nanofibrilation. After the pre-treatments, the fibers were mechanically fibrillated to produce cellulose micro/nanofibrils, which were made into films to be analyzed. Fibers pre-treated with 5 wt\% NaOH produced 59\% micro/nanofibrils with average diameter less than 30 nm, for Eucalyptus, and 46\% of micro/nanofibrils, with the same diameter, for Pinus. However, the enzymatic pre-treatment was the most efficient, resulting in 83\% of micro/nanofibrils for Eucalyptus and 78\% for Pinus. This corroborates with the lowest values of the 1.096/2.896 ratio and degree of polymerization, indicating chain shortening in cellulose. X-ray diffraction and Raman microspectroscopy crystallinity results presented similar tendencies, with increased crystallinity caused by all pre-treatments, being 5 wt\% NaOH for 2 h the highest, with 70\%, for Eucalyptus and Pinus. Enzymatic pre-treatment has produced the best fibrillation and greater crystallinity. The presentwork has shown a reliableway of assessing cellulose structure using Raman microspectroscopy.
The principal aim of the present study is to develop a method for the production of cellulose nanofibers, from the banana peel (BP) and bract (BB). It is also the aim of this study to produce cellulose-based biopolymers through acetyl and lauroyl modifications. The microwave digestion method and ball milling assisted ultra-sonication method was optimized for sustainable extraction of micro and nano cellulose fibers, respectively. The microwave digestion method was found to be effective in the removal of hemicellulose and lignin. Micro and nano cellulose fibers of BP and BB were found to contain type I cellulose structure. Thermal stability and crystallinity index of cellulose nanofibers were examined to be higher than it's native micro cellulose. Nano cellulose fibers were examined to be a potential source for production of acetyl and lauroyl cellulose, with a high degree of substitution and thermal stability. Hence, microwave digestion and ball milling assisted ultra-sonication method was proven to be effective in the extraction of nano cellulose fiber for development of cellulose-based polymers.
The medium of solid-state fermentation (SSF) is a multiphase system, whose complex physical properties cause difficulties of the cognition of SSF process and the process control. This paper aimed to deeply analyze the mechanical, structural and thermal properties of solid-state medium, explored relationships between the medium's physical properties and fermentation performance, then to guide the process control and culture medium optimization for SSF. A mechanical property index (I-mp), which was the product of resilience, cohesiveness, and springiness, was established to fully characterize physical properties of medium. Results showed at the initial stage of SSF, there were positive correlations of I-mp with thermal conductivity and water retention, negative correlations with gas permeability and thermal diffusivity, and a parabolic relationship with biomass content with a symmetry-axis at I-mp = 4.37 x 10(-2). Correlations were further verified in SSF dynamic process. During the first 100 h, I-mp <= 4.37 x 10(-2) was positively correlated with heat conduction and water retention in medium, which was beneficial for cell growth; while when I-mp > 4.37 x 10(-2) during 100-168 h, medium heat accumulation, poor heat diffusivity and poor gas permeability indicated the reduction of fermentation performance. Results revealed medium physical properties significantly affected heat and mass transfer and further influenced fermentation performance in SSF. Mechanical property index I-mp could well comprehensively characterize physical properties of medium, which could be useful for guiding initial culture medium preparation and SSF process control. (C) 2017 Elsevier Ltd. All rights reserved.
The unique selectivity of enzymes, along with their remarkable catalytic activity, constitute powerful tools for transforming renewable feedstock and also for adding value to an array of building blocks and monomers produced by the emerging bio-based chemistry sector. Although some relevant biotransformations run at the ton scale demonstrate the success of biocatalysis in industry, there is still a huge untapped potential of catalytic activities available for targeted valorization of new raw materials, such as waste streams and CO2. For decades, the needs of the pharmaceutical and fine chemistry sectors have driven scientific research in the field of biocatalysis. Nowadays, such consolidated advances have the potential to translate into effective innovation for the benefit of bio-based chemistry. However, the new scenario of bioeconomy requires a stringent integration between scientific advances and economics, and environmental as well as technological constraints. Computational methods and tools for effective big-data analysis are expected to boost the use of enzymes for the transformation of a new array of renewable feedstock and, ultimately, to enlarge the scope of biocatalysis. (C) 2017 Elsevier B.V. All rights reserved.
Nanocrystalline cellulose (CNC) has been extensively developed in various fields such as nanostructure and food systems enhancers. In this study, first a CNC is synthesized through a homogenizer-ultrasound technique plus acid hydrolysis and then its application in biscuit cream is investigated. The morphology results reveal the swelling capacity of the CNC increases 63\%, over raw cellulose and the dynamic light scattering particle size is about 120 nm. The surface morphology results of the CNC shows a spherical shape with an average diameter of 89 nm. The results show an increase in the degree of crystallinity with decreasing thermal stability in the CNC. The best result of the oil stability associated with maintaining the sensory properties is related to the cream formulated with a 50:50 ratio of sunflower oil and shortening after being incorporated with CNCs. It is thus shown to be necessary to optimize the concentration of CNCs to control cream texture characteristics.
In the past few years, the global demand in bioethanol has been continuously rising due to its economic importance. Several countries have exerted considerable efforts in the production of bioethanol as a transport fuel from different feedstocks and started to practice consuming this environment-friendly fuel. Thailand is now one of the top consumers of bioethanol in South East Asia and belongs to the top 5 leading countries in producing pineapples. Production of bioethanol from pineapple wastes, especially the fruit peels, became possible. In this study, the effects of alkaline pretreatment and microbial hydrolysis through Trichoderma harzianum of pineapple fruit peel were evaluated. Among the four concentrations of NaOH, the 0\% NaOH gave the highest total and reducing sugar (458.44 +/- 13.6 g/L and 279.67 +/- 21 g/L) than 1\%, 3\%, and 5\% concentrations of NaOH. Samples pretreated with 0\% NaOH were subjected to microbial hydrolysis which showed an increase in reducing sugar of the samples. At the end of the experiment, a bioethanol yield of 5.98 +/- 1.01 g/L from pineapple fruit peel was successfully produced at 48 h of fermentation.
The water resource crisis and concerns with environmental pollution prompt the necessity to upgrade conventional wastewater treatment processes. The microalgae-based wastewater treatment process has shown many advantages that can fulfill the stricter demands for improved wastewater treatment. Microalgae cultivation can be carried out in different photobioreactors and under different operational conditions. The cultivation of the microalgae biomass provides the bioremediation of some targeted pollutants through uptake/digestion or biosorption, resulting in treated effluent and the production of biomass. This paper reviews the progress in microalgae-biotechnology for industrial wastewater treatment. A brief overview of microalga types/classification, the cultivation photobioreactors type, and conditions was first provided. Next, a comprehensive review of the bioremediation of industrial wastewater, including distillery, heavy metals, textiles, and emerging contaminants, was provided. Finally, perspectives on the potential scale-up of the technology and some critical considerations were also discussed.
Green routes to effectively mitigate the extensive generation of variegated biosolids (VB) from the artisanal basketry sector has been specially constrained with traditional waste management practices. In this investigation, VB is used as a pore forming material in the development of fired clay bricks. Three compositional different bricks formulated with different dosages of VB (i.e., 0, 6 and 12 wt\%) inclusion in brickmaking clay (BC) were fired at 900, 1000 and 1100 degrees C temperatures, and assessed for their physico-mechanical and thermal properties. Weight loss (WL) results showed the bricks WL increased with elevated firing and high addition VB admixed proportion. The highest 12.8\% WL was observed among the BS12-1100 bricks. Fired shrinkage (FS) values were within recommended limits of 2.4-7.6\%. Apparent Porosity (AP) results ranged from 19.3\% to 38.6\%. AP increased by 52.3\% with VB addition but decreased up to 23.83\% due to improved firing. Water absorption (WA) results were mostly found within the quality standards of 9.1 - 19.8\%. Bulk density (BD) variations were observed between 1.3 g/cm3 and 2.2 g/cm3. Compressive strength (CS) reductions were in the acceptable range of 25.0 - 9.1 MPa. The thermal conductivity (TC) test results of the bricks showed a 28.59\% improvement in the thermal insulation properties of the bricks. The Taguchi method revealed BS12-900 brick series as best optimized products due to its acceptable 9.1 MPa CS and least TC (0.452 W/mK). Thus, the usage of VB for brick production has an important contributory role to the economy and ecology of Ghana.
Clay paving blocks made of natural, environmentally friendly materials have their own originality and colorful authenticity, but due to the complex technological production process, they are also relatively expensive products; therefore, their environmental resistance properties are strictly defined and controlled by the standards. The physical and mechanical properties of clay paving blocks are the key factors aiming to ensure the longevity of products and their long-term success in the market. Therefore, ensuring high physical and mechanical properties of clay paving blocks have become a most crucial challenge for the manufactures. This article considers the parameters of the technological production process of clay paving blocks manufacturing and evaluates the influence of the chemical composition of three different types of clay on the physical and mechanical properties of the paving blocks. Water absorption, linear shrinkage, freeze/thaw, acid resistance, and transverse breaking load of clay paving blocks are investigated. This study reveals the importance of raw material selection in the production process of clay paving blocks and provides the concept of main quality factors of clay.
Xylanase and laccase are now used more frequently in biomass biorefinery. Different operational conditions of the two enzymes reflect their limitations for enzyme cocktails. Xylanase and laccase bleaching efficiencies were studied to reveal evidence of their synergistic action on energy cane (EC) structural features. Temperature and pH of both enzymes were optimized to a one-step treatment of mixing enzymes after alkaline pretreatment. Results showed that a single pretreatment of 50 Ug-1 xylanase and 100 Ug-1 laccase significantly enhanced the whiteness index of pretreated fibers by 85\%. Whiteness index increased to 95\% when biobleaching synergistic xylanase/laccase treatment was applied. Synergistic xylanase/laccase-treated fibers showed 70\% xylan removal, with enhanced crystallinity index at 59\% compared to single xylanase and laccase-treated fibers. Synergistic xylanase/laccase treatment increased the specific surface area (2.8 m2g-1) and surface roughness (81.83 mu m) of the fibers, indicating partial xylan hydrolysis and lignin depolymerization. NMR spectroscopy exhibited bond cleavage of lignin-xylan and lignin inter-unit linkages due to enzyme synergistic actions. Results increase the understanding of synergistic action mechanisms between xylanase and laccase to improve biobleaching efficiency and can be implemented to enhance biorefinery production of various lignocellulosic biomass.
This research presents the feasibility of a geopolymer fully prepared using chamotte, ceramic industry residue, and fly ash from olive biomass, residue from the olive oil industry. A typical ceramic characterization was carried out from a mechanical and physical standpoint, aimed at exploring their potential as a building material in order to reuse this currently unused waste and to reduce clay extraction operations. Based on the obtained tests results, binder samples showed promising mechanical properties with compressive strengths of over 50 MPa, leading to sustainable raw materials for traditional ceramics in certain applications. (C) 2020 Elsevier Ltd. All rights reserved.
This study was carried out to evaluate the effects of wet torrefaction (WT) on the combustion reactivity and kinetics of Norwegian forest residues. The wet torrefaction temperature was varied at 175, 200, or 225 degrees C. The combustion of the raw and torrefied forest residues was thermogravimetrically studied in synthetic air (21\% O-2 and 79\% N-2 in volume). The distributed activation energy model (DAEM) with four parallel reactions was adopted for the kinetic analysis. The results show that WT enhances the devolatilization reactivity of the forest residues, but too severe conditions reverse the trend. Moreover, torrefied forest residues are more reactive, and exhibit a broader and longer combustion stage than the raw residues. The extracted kinetic data confirm the removal of hemicellulose from the forest residues after WT. The kinetic parameters of cellulose and lignin increase after WT. In addition, the mass fraction of char is increased gradually with WT severity while its kinetic parameters are decreased by WT. (C) 2016 Elsevier Ltd. All rights reserved.
Lignin is one of the most studied and analyzed materials due to its importance in cell structure and in lignocellulosic biomass. Because lignin exhibits autofluorescence, methods have been developed that allow it to be analyzed and characterized directly in plant tissue and in samples of lignocellulose fibers. Compared to destructive and costly analytical techniques, fluorescence microscopy presents suitable alternatives for the analysis of lignin autofluorescence. Therefore, this review article analyzes the different methods that exist and that have focused specifically on the study of lignin because with the revised methods, lignin is characterized efficiently and in a short time. The existing qualitative methods are Epifluorescence and Confocal Laser Scanning Microscopy; however, other semi-qualitative methods have been developed that allow fluorescence measurements and to quantify the differences in the structural composition of lignin. The methods are fluorescence lifetime spectroscopy, two-photon microscopy, Foster resonance energy transfer, fluorescence recovery after photobleaching, total internal reflection fluorescence, and stimulated emission depletion. With these methods, it is possible to analyze the transport and polymerization of lignin monomers, distribution of lignin of the syringyl or guaiacyl type in the tissues of various plant species, and changes in the degradation of wood by pulping and biopulping treatments as well as identify the purity of cellulose nanofibers though lignocellulosic biomass.
A green approach using hydrogen peroxide (H2O2) to intensify the fuel properties of spent coffee grounds (SCGs) through torrefaction is developed in this study to minimize environmental pollution. Meanwhile, a neural network (NN) is used to minimize bulk density at different combinations of operating conditions to show the accurate and reliable model of NN (R-2 = 0.9994). The biochar produced from SCGs torrefied at temperatures of 200-300 degrees C, duration of 30-60 min, and H2O2 concentrations of 0-100 wt\% is examined. The results reveal that the higher heating value (HHV) of biochar increases with rising temperature, duration, or H2O2 concentration, whereas the bulk density has an opposite trend. The HHV, ignition temperature, and bulk density of biochar from torrefaction at 230 degrees C for 30 min with a 100 wt\% H2O2 solution (230-100\%-TSCG) are 27.00 MJ.kg(-1), 292 degrees C, and 120 kg.m(-3), respectively. This HHV accounts for a 29\% improvement compared to that of untorrefied SCG. The contact angle (126 degrees), water activity (0.51 a(w)), and moisture content (7.69\%) of the optimized biochar indicate that it has higher resistance against biodegradation, and thereby can be stored longer. Overall, H2O2 is a green treatment additive for SCGs solid fuel. This study has successfully produced biochar with greater HHV and low bulk density at low temperatures. The green additive development can effectively reduce environmental pollutants and upgrade wastes into resources, and achieve ``3E{''
In this study, an optimized medium for Clostridium butyricum (CCT7470) was obtained from a Plackett-Burman assay. It was evidenced that glucose (5 g/L), starch (1 g/L) and three nitrogen and vitamin sources (5 g meat extract/L; 5 g peptone/L and 1.5 g yeast extract/L) improved hydrogen (H-2) production. The addition of nanoparticles (NPs) improved the fermentation process, and maximum H-2 production (434 +/- 13 mL) was achieved with 30 mg Fe-0/L and 20 mg Ni-0/L. The metabolic pathway shifted from acetic and butyric to valeric acid production with the addition of NPs. In reactors with NPs, a longer permanence of hydrogenase was observed with hydA quantification by real-time polymerase chain reaction (qPCR). However, the expression of new enzymes, assessed by reverse transcription followed by qPCR (RT-qPCR), was higher in control assay than that in the NPs one. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Bacterial nanocellulose/hydroxyapatite/cellulose nanocrystal (BHC) composites were synthesized via in-situ synthesis using cellulose nanocrystals (CNCs) to improve colloidal stability and the dispersion of hydroxyapatite (HA) during the bacterial nanocellulose (BNC) cultivation period. Transmission electron microscopy images and energy dispersive spectroscopy (EDS) results confirmed the dispersion of HA on the CNC particles with a Ca/P ratio of 1.66 corresponding to that of the stoichiometric HA. The SEM images and EDS results showed that the integration of the HA and BNC network without CNC assistance (BHA (0.25 and 0.5 wt\%) composites) was less than that for BHC at both concentrations. Fourier-transform infrared analysis, XRD and thermal degradation revealed the effect of HA on the BHC composites with a decreased CrI\% and improved thermal property. Cytotoxicity proved the potential for using BHC composites for bone tissue engineering scaffold with cell viability up to 83.4 +/- 3.6\% compared to the negative control (99.2 +/- 0.08\%).
Brazil produces massive amounts of granite sawing waste and coffee husk ash and their inadequate and, often, illegal disposal causes enormous environmental problems. In the past decade, these and other industrial wastes have been intensively studied aiming at determining their potential as alternative raw materials, particularly for the ceramic industry. This work describes research carried out on the joint incorporation of those wastes in ceramic roof tile formulations. The results indicated that the simultaneous use of both materials translates into a very forgivable industrial working range, both composition- and temperature-wise, which, given the technological properties values observed after firing at 1100 degrees C, enables industrial up-grade to wall tile production. As collateral benefits, the use of granite waste and coffee husk ash as alternative raw materials in the manufacture of clay-based products will relieve the stress on feldspars consumption and attenuate waste disposal concerns.
Fossil resources, i e. concentrated carbon from biomass. have been irrecoverably exhausted through modern industrial civilization in the last two hundred years. Serious consequences including crises in resources, environment and energy, as well as the pressing need for direct and indirect exploitation of solar energy, pose challenges to the science and technology community of today. Bioenergy, bulk chemicals, and biomaterials could be produced from renewable biomass in a biorefinery via biocatalysis. These sustainable industries will match the global mass cycle. creating a new form of civilization with new industries and agriculture driven by solar energy. Industrial biotechnology is the dynamo of a bioeconomy, leading to a new protocol for production of energy, bulk chemicals, and materials. This new mode of innovation will place the industry at center stage supported by universities and research institutes. Creativity in industrial biotechnology will be promoted and China will successfully follow the road to green modernization. China's rapid economic development and its traditional capacity in fermentation will place It in an advantageous position in the industrial biotechnology revolution. The development and current status of industrial biotechnology in China are summarized herein
Phenolic compounds released during pretreatment of lignocellulosic biomass influence its enzymatic hydrolysis. To understand the effects of these compounds on the kinetic properties of xylan-degrading enzymes, the present study employed the recombinant cellulosomal endo-beta-1,4-xylanase, thermostable GH11 XynA protein from Clostridium thermocellum, as an enzyme model to evaluate the effects of 4-hydroxybenzoic acid, gallic acid, vanillin, tannic acid, p-coumaric acid, ferulic acid, syringaldehyde, and cinnamic acid. XynA was deactivated by the assayed phenols at 60 degrees C, presenting the strongest deactivation in the presence of tannic acid, with an activity reduction of about 80 \%. Thermal stability of XynA was influenced by ferulic acid, syringaldehyde, cinnamic acid, 4-hydroxybenzoic acid, and p-coumaric acid. The hydrolysis rate of oat-spelt xylan by XynA was influenced by temperature, being unable to hydrolyze at 40 degrees C in the presence of tannic acid. On hydrolysis at 60 degrees C, the presence of gallic and tannic acid caused a major reduction in reducing sugar production, generating 3.74 and 2.15 g.L-1 of reducing sugar, respectively, whereas the reaction in the absence of phenols generated 4.41 g.L-1. When XynA was pre-deactivated by phenols it could recover most of its activity at 40 degrees C, however, at 60 degrees C activity could not be reestablished.
tfxa (GenBank: U01242), which encoded the mature peptide of Thermomonospora fusca TF xylanase A (TfxA), was high-level expressed in Escherichia coli BL21 (DE3). The recombinant xylanase, reETfxA, was both secreted into culture medium and in the cytoplasm. reETfxA showed high xylanase activity and was purified to homogeneity by Ni-affinity resin (182.8 and 681.4 U mg(-1) for crude and purified enzyme, respectively). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blot analysis revealed that the molecular mass of reETfxA was approximately 42.7 kDa. The reETfxA was immobilized on a novel mesoporous SiO2 microsphere (MSM)-coated chitosan via covalent bonds, which formed from Schiff base reaction between supports and enzyme. The binding capacity of the prepared MSM-coated chitosan particles to reETfxA was approximately 272.6 mg g(-1)-particles. The optimum temperature values of the free and immobilized reETfxA were 65 and 70 A degrees C, respectively. Moreover, the optimum pH values of the free and immobilized reETfxA were pH 6.0 and 5.0, respectively. The reETfxA showed relatively high thermostability. When treated at 70 A degrees C and pH 6.0 for 15 min, the residual activities of free and immobilized reETfxA were 84.2 and 100.2\%, respectively. The results obtained from the HPLC analysis showed that immobilized reETfxA released xylooligosaccharides from oat spelt, beechwood and birchwood xylans, with xylotetraose, xylotriose, and xylopentaose as the major products, respectively. Additionally, the immobilized reETfxA could directly hydrolyze the wheat bran insoluble xylan.
Pathogenic microbes are a major source of health and environmental problems, mostly due to their easy proliferation on most surfaces. Currently, new classes of antimicrobial agents are under development to prevent microbial adhesion and biofilm formation. However, they are mostly from synthetic origin and present several disadvantages. The use of natural biopolymers such as cellulose, hemicellulose, and lignin, derived from lignocellulosic materials as antimicrobial agents has a promising potential. Lignocellulosic materials are one of the most abundant natural materials from renewable sources, and they present attractive characteristics, such as low density and biodegradability, are low-cost, high availability, and environmentally friendly. This review aims to provide new insights into the current usage and potential of lignocellulosic materials (biopolymer and fibers) as antimicrobial materials, highlighting their future application as a novel drug-free antimicrobial polymer.
Levoglucosan is served as a significant versatile product to generate high value-added chemicals and pharmaceutical additives. Levoglucosan was predominately produced from pyrolysate of cellulose. However, the direct fast pyrolysis of waste biomass produces a small quantity of levoglucosan in comparison with the theoretical value of cellulose. This study explored Fenton pretreatment as a possible route to enhance levoglucosan yield during the fast pyrolysis of the waste corncob. The experimental results showed that different Fenton pretreated conditions and pyrolytic temperatures played vital roles in the formation of levoglucosan. The levoglucosan yield from fast pyrolysis at 500 degrees C of corncob pretreated by Fenton reaction of 14 mL/g H2O2 and 16 mM FeSO4 was about 95\% higher than that of the untreated corncob. Additionally, Fenton pretreated corncob was capable of obtaining the levoglucosan at a low pyrolytic temperature (300 degrees C). It was mainly attributed to the effective disrupting of biomass structures and the selective degradation of lignin and hemicellulose during pretreatment. Furthermore, the powerful removal of alkali and alkaline earth metals during Fenton pretreatment was beneficial to increasing the levoglucosan yield. These findings demonstrate that Fenton pretreatment can provide a novel effective method to enhance levoglucosan yield during biomass fast pyrolysis. (C) 2020 Elsevier Ltd. All rights reserved.
Biomass conversion processes have become increasingly important to mitigate fossil fuel consumption and to increase the contribution of renewable fuels into the world energy matrix. In this study, Eucalyptus urograndis wood chips were pretreated by autocatalytic steam explosion to produce cellulosic ethanol after enzymatic hydrolysis and fermentation. These experiments were organized in a central composite rotatable design using temperatures and reaction times ranging from 174 to 216 degrees C and from 4 to 11 min, respectively. Mass yields, cellulose degree of polymerization, and glucose yields after enzymatic hydrolysis showed a linear correlation with pretreatment severity. The best condition was set at 210 degrees C for 5 min due to its higher glucose yield after pretreatment and enzymatic hydrolysis. Pectins were almost completely solubilized after pretreatment while galactoglucomannans were more resistant to acid hydrolysis than arabinoglucuronoxylans. Alkaline delignification led to 90.3\% lignin removal from steam-exploded materials, but its effect on enzymatic hydrolysis was almost negligible. For the best pretreatment condition, analyses by confocal laser scanning microscopy and solid-state nuclear magnetic resonance revealed important changes in fiber morphology and chemical composition, respectively. Enzymatic hydrolysis at 4 wt \% total solids with Cellic CTec2 and Cellic CTec3 (Novozymes) led to 22.4 and 27.8 g L-1 glucose equivalents in 96 h, respectively, whose fermentation with a commercial strain of Saccharomyces cerevisiae led to ethanol productivities greater than 3.5 g L-1 in 6 h.
Functionalized-cellulose nanowhiskers (CNWs) were obtained and used to improve hydroxyapatite (HAp) growth by the biomimetic method. CNWs were obtained through HCl hydrolysis and then submitted to chemical functionalization with carboxylate or amine groups that can induce selective HAp mineralization efficiently. Functionalized-CNWs were tested against HAp growth through the biomimetic method using a simulated body fluid (SBF) as a medium during 14 and 28 days of mineralization. Both chemical surface nature (bearing carboxylate or amine reactive groups) and contact time with SBF influenced the nucleation and growth of HAp crystals over CNWs surface. Nanocomposites immersed for 28 days showed a higher amount of HAp crystals compared to bare CNWs or the ones immersed for 14 days. Biocompatibility of the nanomaterials immersed for 14 days in SBF was evaluated through cell viability test using pre-osteoblasts (MC3T3-E1). In general, functionalized-CNWs containing HAp crystals deposited through biomimetic method showed promising results, with CNWs bearing amine groups showing a slightly larger biocompatibility compared to the ones bearing carboxylate groups during an incubation period of 24 h. (C) 2018 Elsevier B.V. All rights reserved.
Pectinase production by Aspergillus niger LB-02-SF was studied in a bench-scale rotating drum bioreactor. With 30\% of the bioreactor volume occupied, agitation promoted increasing fungal growth and decreasing enzyme production, whereas with 50\% occupation, an opposite trend occurred. The interval between agitation events was evaluated for an occupation volume of 70\%, and no difference in enzyme production was observed for the 90 and 120 min intervals; for the 60 min intervals, however, the activity was reduced. Cultivations performed without temperature control attained 45 degrees C and showed maximum enzyme activity almost four times superior to cultivations controlled at 30-37 degrees C. Air flow rates between 0.18 and 0.90 L of air per kilogram of medium per minute were evaluated for 30 and 50\% of the occupation volume. Fungal growth and pectinase production were favoured by the smallest and largest occupation volumes, respectively, with an intermediate air flow. The results of this work indicate that the best conditions for biomass growth are not the best for the production of pectinases. (c) 2017 Elsevier Ltd. All rights reserved.
In recent years, the interest in fungi and lignocellulosic residues as a source of enzymes production has increased, due to the high production costs that hinder the development of this technology. Recent studies have been carried out with the objective of increasing the efficiency of enzyme production by new microbial strains with potential in the synthesis of proteins and low-cost and more effective fermentation techniques. In this study, a Taguchi orthogonal matrix design and analysis of variance (ANOVA) was employed to optimize the parameters of the solid-state fermentation (SSF) process using Aspergillus niger CECT 2700 and brewery spent grain (BSG) as a substrate to improve cellulase and xylanase enzyme production. The independent variables at three levels were moisture (60, 70, and 80\%), bed loading (2, 4, and 6 g), and fermentation time (3, 5, and 7 days). Cellulase and xylanase activities in units per gram of dry residue (U/gdr) were the response variables. The results indicated that bed loading was the variable that most affected enzyme production. The optimal parameters were 80\% moisture, 2 g of bed loading, and 5 fermentation days, resulting in a maximum of 3.63 +/- 0.39 U/gdr of cellulase activity and 2210.23 +/- 138.50 U/gdr of xylanase activity. This study showed the potential use of Taguchi design by A. niger strain and the economic lignocellulosic residue BSG as an alternative to improve the cellulose and xylanase enzymes production.
Ferulic acid (FA) and p-coumaric acid (pCA) are high-value products that can be obtained by alkaline hydrolysis of lignocellulose. Present work explores the potential of surfactant-based cloud-point extraction (CPE) for FA and pCA extraction from corn cob hydrolysate. More than 90 \% (w/w) extraction of both FA and pCA was achieved from model system with L92. The partition coefficient of FA and pCA in L92 aqueous phase system was 35 and 55, respectively. A significant enrichment (8-10-fold) of both FA and pCA was achieved in surfactant-rich phase. Furthermore, the downstream process volume was reduced by 10 to 13 times. Optimized conditions (5 \% v/v L92 and pH 3.0) resulted into 85 and 89 \% extraction of FA and p-CA, respectively, from alkaline corn cob hydrolysate. Biocompatibility tests were carried out for L92 for ethanol fermentation and found to be biocompatible. Thus, the new surfactant-based CPE system not only concentrated FA and pCA but also reduced the process volume significantly. Further, aqueous phase containing sugars can be used for ethanol fermentation.
The performance and stability of a two-phase partitioning bioscrubber (TPPB) containing 33\% (vol.) n-hexadecane as an immiscible phase was investigated during 30 days of continuous gaseous benzene treatment. Elimination capacities of 141 +/- 12 g/m(3) h were achieved by Achromobacter xylosoxidans Y234 while maintaining > 99\% removal throughout. A new steady-state operating strategy that limits excessive biomass production by directing substrate consumption to maintenance energy has eliminated the requirement for frequent exchange of liquid contents. Simplifying the operating protocols in this manner has dramatically reduced material costs and rendered the TPPB operational requirements as more comparable (in terms of frequency of required operator inputs) with other vapor-phase bioreactors. The practicality of the proposed simplification to the operating protocol was confirmed by demonstrating that intermediate metabolites were not accumulating in the TPPB, inorganic nutrient requirements were readily predictable, and that high culture viability could be sustained for prolonged cell retention times (30 days).
The use of plant biomass ash, as partial replacing binder in cement-based structural mortars or grouts, is an interesting eco-friendly alternative within the building industry. Besides, recycling those ashes makes possible to reduce the polluting wastes that are accumulated in landfills, improving sustainability. On the basis of the data obtained from the literature, this paper analyses the feasibility of using plant biomass ashes in eco-efficient structural mortars or grouts. The research focuses on issues that are directly related to the pollution mitigation and to the structural performance. Physical-chemical properties (pozzolanic activity and mechanical characteristics), rheological behaviour, setting times and drying shrinkage, durability and environmental features are analysed. In addition, the global warming potential and embodied energy of the plant biomass ashes- based mixtures are calculated, assuming that they will be used to grout hollow concrete units (CMUs), in order to obtain green grouted blocks. Advantages and disadvantages of each waste as cement substitute are highlighted. Besides, the properties or characteristics that require additional research are pointed out (e.g. durability and environmental impact). Conclusions from this work could be used to foster further research on the use and development of those eco-efficient building materials. (C) 2017 Elsevier Ltd. All rights reserved.
The biological valorization of cork depends mainly on the weakening of cell wall recalcitrance. As a typical softwood, Chinese fir is more resistant to enzyme and microbial invasion than most biomass. This study compared the efficiency of two single-step pretreatments (dilute sulfuric acid pretreatment (DSA) and acidic sodium chlorite pretreatment (SC)) and their interaction effects on the pretreatment process. Two single pretreatments could selectively remove hemicellulose and some lignin from Chinese fir sawdust (CFS). Combined pretreatments resulted in a remarkable synergistic enhancement in delignification. The hemicellulose-removal-first strategy is favored by softwood delignification, the destruction of fiber morphology, and the redistribution of lignin. Using DSA-SC, more than 90\% of lignin and hemicellulose were removed, and complete hydrolysis (99.3\%) was obtained. Based on DSA-SC, the CFS biorefinery recovered 41.6\% lignin and 52.8\% hemicellulose sugar, and 306.1 g lactic acid was produced from 1000.0 g CFS. The integrated pretreatment process with a stepwise separation feature could be effectively applied in softwood destruction and provide more opportunities for softwood waste whole-component utilization.
As of 2020, the annual generation of municipal solid waste (MSW) in China has surged to 235.12 Mt, and food waste (FW) accounts for more than 60 \%. The most common treatment method is incineration, which accounts for 62.13 \%. This research proposes a three-stage pretreatment method for FW that is suitable for incineration while recovering by-products and energy from the pretreatment process. The first stage is dehydration; compared to hot air drying (HAD) processes, freeze drying (FD) exhibits a higher dehydration and oil preservation rate, allowing for the preservation of organic matter content and the recovery of freshwater resources from FW. The second stage is oil recovery; the FW extracted oil (FWEO) can be used to produce biodiesel, and this stage also helps to improve the effectiveness of the subsequent torrefaction process. The third stage improves the energy and fuel characteristics of the organic residue of FW and enhances the combustion performance optimizing the torrefaction temperature. The solid fuel obtained at a torrefaction temperature of 350 ? shows the best combustion performance, with a solid yield of 35.76 \%, a torrefaction temperature of 300 ? might chosen to further improve the solid yield.
A lignin extraction procedure was developed for improving extraction yield, mitigating structural changes, and retaining depolymerization performance of the lignin fraction from hydrothermal and ball-milling treated miscanthus. The remaining residues after the lignin extraction process were subjected to enzymatic hydrolysis for evaluating the possibility of producing fermentable sugars. The extraction yield was improved by a factor of 5 due to hydrothermal treatment, and its extract contained approximately 50 g/L of total phenolic compound. The high molecular weight lignin fraction (Mw: 5640-6850 Daltons) was highly dissolved in 80\% and 96\% dioxane solution, but the low molecular weight part (Mw: 4170-5270 Daltons) was detected regardless of conditions. The major depolymerization products of HML are 4-vinylphenol (6.6 mg/g) and 2-methoxy-4-vinylphenol (4.3 mg/ g). 90\% of glucose yield was obtained after enzymatic hydrolysis of the extraction residue. Overall, both yields of lignin extraction and enzymatic hydrolysis of residue were improved by combining hydrothermal and ball-milling treatment and changing the solvent combination.
Peanut shells (i.e., an abundant industrial by-product) were subjected to an innovative hydrothermal pretreatment approach using high-pressure CO2 to enhance their enzymatic hydrolysis conversion into glucose. This pretreatment led to a reduction in hemicellulose content in the pretreated peanut shells from 12.4\% to as low as 1.8\%, which facilitated subsequent conversion into glucose by enzymatic hydrolysis. This pretreatment approach was assessed within a 170-200 degrees C temperature range and a 20-60 bar CO2 pressure range, after which the results of these conditions were compared to those of conventional hot water pretreatment. Treatment at 190 degrees C and a 60-bar CO2 pressure was determined to be optimal, resulting in the highest glucose yield (80.7\%) from subsequent enzymatic hydrolysis. Acidic conditions resulting from CO2-derived carbonic acid significantly reduced the hemicellulose content of the peanut shells and weakened the interaction between cellulose, hemicellulose, and lignin, improving enzyme accessibility to the cellulose. Furthermore, high-pressure CO2 increased the pore size and porosity of the resulting pretreated peanut shells, improving their enzyme adsorption capacities, as confirmed by cellulase adsorption and mercury intrusion porosimetry tests. The dual effect from high-pressure CO2 led to significant hemicellulose reduction and improved adsorption of enzymes on the cellulose, which in turn increased glucose yield from the subsequent enzymatic hydrolysis of pretreated peanut shells. Alcoholic fermentation of the hydrolyzed glucose resulted in a 12.4\% increase in bio-ethanol production compared to a glucose control, thus highlighting the potential of pre-treated peanut shells as a glucose precursor used in biofuel industry.
Antioxidant activity of xylooligosaccharides (XOS) released from beechwood and birchwood glucuronoxylans by two different xylanases, one from family GH10 (Xyn10A) and another from family GH30 (Xyn30D) was examined. The ABTS (2, 2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) method was used, since it resulted more accurate for the antioxidant activity determination of XOS. Thin layer chromatography and MALDI-TOF MS analysis showed that Xyn10A produced a mixture of neutral and acidic XOS whereas the XOS produced by Xyn30D were all acidic, containing a methylglucuronic acid (MeGlcA) ramification. These acidic XOS, MeGlcA substituted, showed a strongly higher antioxidant activity than the XOS produced by Xyn10A (80\% vs. 10\% respectively, at 200 mu gmL(-1)). Moreover, the antioxidant activity increased with the degree of polymerization of XOS, and depended on the xylan substrate used. The antioxidant capacity of eucalyptus autohydrolysates after xylanase treatment was also analysed, showing a decrease of their antioxidant activity simultaneous with the decrease in XOS length.
Sago (Cycas circinalis) seed shells are agricultural waste materials discarded after taking the pith. In the present study Cellulose nanocrystals (CNCs) are isolated from the sago seed shells by acid hydrolysis. The hydrolysis was performed with 64\% (w/w) sulphuric acid. The resulting CNCs were characterized by FTIR, XRD, SEM, TEM, AFM, DLS, Zeta (zeta) potential and TGA. FTIR spectrum of CNCs shows similar frequencies as that of alpha-cellulose, but with reduced intensity. XRD diffraction pattern shows co-existence of cellulose I and cellulose II with crystallinity index of 72\% for cellulose II, 69\% for cellulose I and crystallite size dimension of 9.4 nm for cellulose I. SEM analysis clearly reveals the considerable size reduction during acid hydrolysis. TEM analysis shows that the isolated CNCs contain networked structures and almost spherical shaped particles having 10-15 nm in size. Morphological examination through AFM also shows that isolated CNCs are in nano dimensions, having the size similar to 50 nm. DLS analysis gives an average size of 50 nm and zeta (zeta) potential measured has a value of -37.8 mV. DLS and AFM analyses support each other. TGA reveals lower thermal stability for CNCs.
Currently, xylooligosaccharides (XOs), which are a kind of nutraceutical that can be produced from lignocellulosic biomass, have an important place in the global market. In this critical review the raw materials and manufacturing methods of XOs are briefly considered. The results in some publications indicate that the pre-hydrolysis liquor (PHL) from dissolving pulp process is a potential source of XOs. However, it is very difficult to separate and further remove the lignin in PHL, which is detrimental to the separation and further purification of XOs. Based on these problems, a number of important aspects with respect to PHL, including industrial treatment technologies, composition, and lignin removal technologies, are described in this review. In addition, some XOs purification technologies in PHL are also introduced.
In this work, a non-conventional biomass (mango seed shell) was evaluated for its potential to produce biofuels. Thus, some characterization techniques were performed, including thermogravimetric analyses (TGA), proximate and ultimate analyses, calorific value, compositional analyses, infrared spectra and analytical pyrolysis. Results from proximate analyses showed that mango seed has a good potential for bio-oil generation. The kinetic study showed that the independent parallel reaction model provides a good representation of the kinetic pyrolysis of the studied biomass. The analytical pyrolysis results showed the presence of important chemical products such as furfural, acid acetic, 1,3-pentadiene and phenolic compounds. (C) 2016 Elsevier B.V. All rights reserved.
Schizochytrium sp. has received increasing attention as promising commercial resource for the sustainable production of lipids, due to their fast growth rate and high lipid content. However, the price of glucose represents a significant proportion of the total substrate cost. Therefore, in this study, the lignocellulosic hydrolysate of corn stover hydrolysate (CSH) was used as low-cost culture medium to replace glucose in Schizochytrium sp. fermentation. When Schizochytrium sp. HX-308 was fermented with 20\% glucose from CSH and 80\% of glucose from pure glucose, the lipid production reached 21.2 g L-1, which is lower than that of using 100\% of pure glucose. However, the shifts of fatty acid composition indicated that CSH has great potential to enhance the percentage of polyunsaturated fatty acids (PUFAs) in total lipids. However, as the second largest carbon source in CSH, xylose was not utilized by the Schizochytrium sp. HX-308, and further analysis showed that probably because it does not possess a functional xylulose kinase. In addition, the degradation products in lignocellulosic hydrolysate have a strong inhibitory effect on cell growth, so it is necessary to investigate the tolerance of Schizochytrium sp. HX-308 to degradation products. Here, the effects of five typical degradation products on the growth and lipid synthesis were further investigated. Schizochytrium sp. HX-308 showed good tolerance to furan derivatives and organic acids, but low tolerance to phenolic compounds. Furthermore, in order to improve the lipid accumulation using CSH, the two-stage fermentation strategy was developed, resulting in a 54.8\% increase compared to that of the one-stage strategy. In summary, this study provides a reference for further fermentation engineering with cheap lignocellulosic biomass as substrate.
Now a days lignocellulosic biomass based bioethanol production has been the centre of major research studies due to its varying significances. Bioethanol production by using lignocellulosic biomass as substrate is an economically feasible process. In the current study, very less concentration of sodium hydroxide was used for delignification (pretreatment) and blends of various cellulases was used for enhanced hydrolysis of carbohydrates (cellulose and hemicellulose). It was seen that most noteworthy measure of reducing sugar (40.50 mg/mL) was acquired from Brassica juncea, when it was delignified using 0.5 M sodium hydroxide at 160 degrees C, 10\% solid loading and 30 min duration. The affectivity of above pretreatment (delignification) process was further confirmed by characterization of substrate (control and pretreated) through using SEM, XRD and FTIR. Mixture of cellulases obtained from Fusarium incarnatum KU377454 (isolated by us), Aspergillus niger MTCC284 and Trichoderma harzianum MTCC8230 was utilized for carbohydrate hydrolysis (saccharification) of delignified biomass which demonstrated highest reducing sugar production (62.35 mg/mL) at 15\% solid loading, 50 degrees C temperature and 48 h of time duration. The current process of enzymatic hydrolysis and thermochemical pretreatment by using mixture of cellulases showed efficient reducing sugar production without the use of any costly chemicals and commercial enzymes. (C) 2020 Elsevier B.V. All rights reserved.
In this study, composites of high-density polyethylene (HDPE) with uncoated sisal fibers (UF) and that coated (CF) with polystyrene (PS) and vinyltrimethoxysilane (VTMS) copolymers (PSV) were fabricated. The prepared copolymers containing 2.5\% VTMS (PSa) and 5\% VTMS (PSb) were used to coat the sisal fiber with a thin layer of hydrophobic polymer to make coated fibers CFa and CFb, respectively. The coating process was verified by Fourier-transform infrared spectroscopy (FTIR) analysis. The mechanical, water absorption, morphology, and biodegradation properties of HDPE and its composites with UF (HUF) and CF (HCF) composites were evaluated. The tensile strength and flexural strength were improved by 19.5\% and 34\% after addition of 5\% CFb to HDPE compared to HDPE composite which contains 5\% UF. The results manifested significant reduction in the amount of water absorbed by CF and HCF composites compared to UF and HUF composites. Additionally, scanning electron micrographs indicated that the coating of sisal fibers with PSV improved the compatibility between sisal fibers and HDPE polymeric matrix. Also, the composites containing CF exhibited a lower rate of degradation than those containing UF.
As potential CO2 adsorbents, carbon materials have recently gained attention because of their low energy penalty, abundant sources and good stability. In this study, the response surface methodology (RSM) was used to guide the pitch-based activated carbon preparation and CO2 adsorption at different temperatures. Based on this experimental design, the correlations of CO2 uptakes at different temperatures, as well as the coupling effects of the preparation conditions on CO2 uptake, were analyzed by mathematical modelling. The obtained optimal carbon sample AC650-1.25-2.5 showed a high atmospheric CO2 uptake of 3.15( +/- 0.14), 2.05( +/- 0.02), and 1.37( +/- 0.11) mmol/g at 25 degrees C, 50 degrees C, and 75 degrees C, respectively. Furthermore, the analysis of variance confirmed that the key factor to determine CO2 uptake at 25 degrees C was the activator ratio, contributing to 77.8 \% of the total variance; however, it gradually shifted to the activation temperature and its coupling effect with other factors for CO2 uptake at 75 degrees C. The linear regression and significance test of CO2 uptakes showed that using CO2 uptake at 25 degrees C to predict the uptake at 50 degrees C was feasible; however, it failed to work when predicting the CO2 uptake at 75 degrees C. The good linear relationship of CO(2 )uptakes at similar adsorption temperatures benefited from the existence of sharable effective pore width. It was also concluded that the strict requirement for extremely narrow ultra-micropores led to the non-coincidence of suitable preparation conditions, corresponding to a good CO2 uptake at different adsorption temperatures; this further led to the bad predictability when the adsorption temperature varied greatly.
Banana is one of the most important fruit crops around the world. After harvesting, it generates large amounts of lignocellulosic residues that could be used for second generation ethanol production. Optimal operating conditions of saccharification and fermentation processes, of the two main agricultural wastes of banana crop: pseudostem and rachis, for bioethanol production were selected in order attain conditions transferable to industry (optimizing resources and time). Both materials were previously pretreated with acid-catalyzed steam explosion. Full factorial experimental design was used in order to determine enzymatic hydrolysis process conditions to obtain glucose concentrations between 75 and 100 g.L-1. Optimal enzymatic hydrolysis conditions for rachis and pseudostem were 17.6\% of solid loading and 16.0 FPU.g(-1) glucan of enzyme dosage and 15.1\% of solid loading and 14.9 FPU.g(-1) glucan of enzyme dosage, respectively. The most suitable configuration to attain the highest volumetric ethanol productivity for rachis was 8 h prehydrolysis followed by a Simultaneous Saccharification and Fermentation (PSSF 8 h). Meanwhile, for pseudostem, higher ethanol production was obtained in Simultaneous Saccharification and Fermentation (SSF) configuration. At optimized conditions, pseudostem reached 112 L.t(-1) of ethanol, and rachis 103 L.t(-1). These conditions led to achieve ethanol production process at high solid loading, low enzyme dosage, low yeast inoculum, no mineral salts supplementation and maximum ethanol productivities.
Hydrothermal carbonization, an environmental friendly treatment method was employed to pretreat bamboo for hydrochar preparation in the present study. Hydrothermal carbonization could elevate the fuel properties and combustion behavior of bamboo. The combustion kinetic parameters of raw bamboo and hydrochars were calculated by a simple Arrhenius equation based on the thermogravimetric curves. Two distinct zones were observed for raw bamboo and hydrochars. The activation energies of raw bamboo in zone 1 and zone 2 were 109.5 kJ/mol and 46.6 kJ/mol, respectively, in the heating rate of 20 degrees C/min. The activation energy of hydrochar in zone 1 increased at the hydrothermal carbonization temperature under 220 degrees C and then decreased at higher hydrothermal carbonization temperature, due to the decomposition of relative reactive compounds in bamboo, and destruction of cellulose and hemicellulose structures, respectively. The activation energies of hydrochars in zone 2 were among 52.3-57.5 kJ/mol, lower than that of lignin extracted from bamboo. (C) 2016 Elsevier Ltd. All rights reserved.
Bioconversion of biodiesel-derived glycerol into 2,3-butanediol has received recently much attention due to its increasing surplus and its multiple uses in industry as bulk chemical. The influence of initial glycerol concentration on 2,3-butanediol production in batch runs has been studied. A concentration higher than 140 g/L produces an inhibitory effect on the final 2,3-butanediol concentration and its production rate. In batch mode, the highest yield respect to the theoretical maximum yield (71\%) was reached employing 140 g/L as initial concentration 140 g/L. Based on these results, a high 2,3-butanediol production has been achieved through a fed-batch strategy. The reached 2,3-butanediol concentration was 90.5 g/L from pure glycerol and 80.5 g/L from raw glycerol. The 2,3-butanediol yield respect to the theoretical maximum yield was also improved through the fed-batch operation (90\%). To date, this concentration is the highest produced amount employing as biocatalyst a non-pathogenic bacterium (level 1).
Lignocellulosic biomasses are strongly connected composites of cellulose, hemicelluloses, and lignin. A pretreatment is required in order to make these components available for their later conversion into chemicals. At this point, two strategies have to be considered: to either produce chemicals via microorganism or enzymes (1), or by chemical conversion (2). The focus of this article is the second strategy, which is chemical conversion, performed in water to produce the final products furfural and 5-hydroxymethylfurfural (HMF). Reviewed first is the composition of cellulose and hemicelluloses as well as their degradation chemistry in water. Then, fundamental modes of action and process parameters of pretreatment methods in aqueous solution are summarized. The pretreatment methods discussed here are steam explosion, treatment with hot liquid water, diluted and concentrated acids, as well as alkaline solutions. Finally, the advantages and disadvantages of these pretreatments are discussed for lignocellulosic biomass.
A new coupled process was developed by combining several technologies including biomass pretreatment, direct biomass-to-electricity conversion and electrochemical reduction of the CO2 produced during microbial fermentation of the enzymatic hydrolysate of pretreated substrates. This process was achieved by the assistance of several electron carriers for mediating the transfer of biomass endogenous electrons. Pretreatment of corn stover to increase cellulose accessibility for bioethanol production with the electron carriers being reduced works as a ``charging{''
Conventional masonry units are made of clay with high temperature kiln firing or Ordinary Portland Cement (OPC) concrete mix. However, these conventional masonry unit production methods require intensive energy inputs and abundant raw materials. This predicament has led the researchers to look for sustainable methods of producing masonry units. Subsequently a research has been carried out to develop cement masonry unit incorporating Untreated Rice Husk Ash (URHA) and Water Treatment Sludge (WTS). Especially an attempted has been made to partially replace OPC and Quarry Dust (QD) by URHA and WTS, respectively. Totally nine different mix proportions of OPC, URHA, WTS and QD were used. The mechanical and durability characteristics of those masonry unit specimens were investigated to verify the suitability of the proportions. No significant changes in the mechanical and durability properties were noted in replacing OPC by URHA up to 15\%. However, replacement of QD by WTS considerably deteriorated the mechanical and durability properties. Therefore, it was proposed to incorporate maximum of 15\% URHA and WTS for the production of masonry unit as it complies with the strength requirements of EN 1996-1-1:2005 and EN 1998-1:2005 for masonry structures.
Cotton gin waste was collected from a cotton ginning plant in Virginia and characterized before and after steam explosion to evaluate its potential applications for higher value products such as ethanol. The raw cotton gin waste had high levels of ash (10.5 wt\%) and acid insoluble material (28.8 wt\%). The xylan and cellulose contents were, respectively, 9 and 37 wt\%. The cotton gin waste was steam exploded in a batch gun at severities ranging from 2 to 4.9. Substantial solubilization/degradation of fiber material (9-17 wt\%) occurred during steam explosion pretreatment especially at the high severities. Mannan, galactan, and arabinan were completely solubilized/degraded at severities greater than 3.56. Both glucan and xylan were solubilized/degraded at all severities, but xylan loss was considerably higher. The steam exploded material was essentially cellulose and acid insoluble material and small fractions of xylan at severities greater than 3.56. Steam explosion improved the enzyme hydrolysis of the material from 42\% to 67\% during 24 h incubation. E. coli KO11 was effective in converting the enzyme hydrolyzed substrate to ethanol. The highest ethanol yield (83\% of theoretical yield) was achieved for material treated at a severity of 3.56. Both xylose and glucose were fermented to ethanol by the microorganism. (C) 2001 Elsevier Science Ltd. All rights reserved.
Ethanol is considered the most potential next generation automotive fuel because it is carbon-neutral and could be produced from renewable resources like lignocellulosic biomass. There are some technological barriers such as pretreatment, saccharification of cellulose and hemicellulose matrix, and simultaneous fermentation of hexose and pentose sugars which needs to be addressed for efficient conversion of lignocellulosic biomass to bioethanol. This paper reviews the various process options and kinetic models adopted towards resolving the technological challenges to develop a low-cost commercial process.
This research aimed to establish a methodology for isolating and characterizing nanofibrillated cellulose (CNF) from Stipa obtusa, using low concentrations of reagents and their characterization. The fibers were collected in high Andean areas of Cusco in Peru, treated with the alkaline-assisted steam explosion, followed by bleaching and acid fibrillation procedures, and with steam explosion, using solutions with varying concentrations of oxalic acid. The CNF was characterized by analytical methods according to TAPPI standards and using XRD, FTIR, SEM, TEM, and TGA techniques. The optimum values for obtaining the CNFs were: alkaline treatment with NaOH 0.5 M and acid treatment with 8\% (m/m) of oxalic acid. These parameters were used to obtain a CNF network with a non-uniform surface and diameters between 19 and 27 nm, 82.97\% (m/m) of cellulose, and a crystallinity index of 52.92\%. Furthermore, the results showed a progressive partial elimination of lignin and hemicellulose at each stage of isolation.
In this study, pretreatment and carbohydrate hydrolysis of two microalgae species including Chlorella vulgaris and Spirulina fusiformis have been investigated. Applicability and efficiency of different physical and chemical methods including heating, ultrasonication, acid, alkaline, and ionic liquid (IL) of 1-butyl-3-methyl imidazolium chloride ({[
In this study, torrefaction effect on thermal decomposition of cattle manure under air atmosphere at different heating rates (10-30-50 degrees C/min) was investigated by thermogravimetric analysis. Iso-conversional kinetic methods of FWO (Flynn-Wall-Ozawa), KAS (Kissenger-Akahira-Sunose) and Starink were used to estimate the activation energy and thermodynamic properties. The results revealed that torrefaction improved the quality of manure, increased the FC/VM, decreased the H/C and O/C ratios and enhanced the energy yield. 1 h torrefaction process at 250 degrees C has increased the calorific value of cattle manure about 14\%. The energy density is increased by 1.27 times. The average Ea values estimated with FWO, KAS, and Starink kinetic methods were obtained as 152.46 kJ/mol (CM), 127.17 kJ/mol (TCM); 153.25 kJ/mol (CM), 122.36 kJ/mol (TCM); 155.93 kJ/mol (CM), 132.48 (TCM), respectively. Kinetics and thermodynamic parameters have shown that torrefaction is significant for energy valorization of cattle manure.
Clostridium strain BOH3 can produce hydrogen from agro-residues based media. This report reveals its ability to utilize fruit waste for hydrogen production. In the first approach, for BOH3 fermentation fruit waste hydrolysates generated from microwave (2.45 GHz for 15 min) or moist heat (121 degrees C for 15 min) treatment were used as substrates, after 24 h the hydrogen production was 2526-3118 ml/l, with the yield 2.43-2.51 mol/mol hexose. In the second approach, strain BOH3 was directly cultured into heterogeneous media supplemented with 52.57 +/- 2.20 g TS/l fruit waste, after 60 h it supported a high level of hydrogen production 10720 +/- 137 ml/l, with the yield 359.97 +/- 12.80 ml/g TS utilized. Further investigation showed that strain BOH3 can excrete 0.35 +/- 0.08 U/ml amylase, 1.22 +/- 0.10 U/ml cellulase, 0.72 +/- 0.10 U/ml pectinase and 3.11 +/- 0.04 U/ml xylanase from fruit waste based media. Consequently, strain BOH3 renders a consolidated bioprocessing for biohydrogen production from fruit waste. (C) 2020 Elsevier Ltd. All rights reserved.
The aromatic composition of lignins is considered an important trait that affects the physico-chemical properties of lignocellulosic biomass. However, our knowledge of the relationship between lignin structure and biomass utilization properties remains limited, especially in monocotyledonous grass species, despite their potential as biomass feedstocks. In this study, we used recently produced rice transgenic lines with distinct lignin monomer compositions, i.e., guaiacyl (G)/syringyl (S)/p-hydroxyphenyl (H) aromatic unit ratios, to study the impact of lignin composition on the chemical reactivity, enzymatic saccharification efficiency and calorific value of rice lignocellulose. The H-lignin-enriched rice transgenic line showed significantly enhanced biomass saccharification efficiency after alkali and acid pretreatments and even without any pretreatment, whereas the S-lignin-enriched rice transgenic line displayed enhanced saccharification efficiency after liquid hot water pretreatment. While we detected no significant differences in biomass heating values between the transgenic rice materials tested, analysis of synthetic lignins comprising only G, S or H units suggested that increased ratios of G or H units could increase the heating value of lignin-based solid biofuels.
The industrial processing of avocado to extract oil, and produce guacamole or sauces generates enormous quantities of peels and seeds (around 2 million tons worldwide in 2019) without commercially valuable applications. However, various studies have suggested the presence of a wide range of interesting compounds in the composition of these by-products. This review depicts a thorough outline of the capacity of avocado residues to be converted into a portfolio of commodities that can be employed in sectors such as the food, cosmetics, pharmaceuticals, environment, and energy industries. Therefore, a novel biorefinery strategy to valorize avocado-processing residues to obtain a polyphenolic extract, pectooligosaccharides, and succinic acid was presented. Additionally, the prospects and challenges facing a biorefinery based on the valorization of avocado residues are presented, particularly its techno-economic feasibility on an industrial scale, aiming for a resourceefficient circular bio-economy.
Chromium (Cr) contamination in groundwater is a serious threat to both the environment and public health, due to its high toxicity and extensive industrial application. Based on previous studies on the enhancement of Cr(VI) bioreduction by phosphorus minerals, it is of great significance to assess its practical application potential. Towards this aim, Cr(VI) bioreduction guided by phosphorus minerals under continuous flow condition was conducted with the variation of initial concentration and HRT, where it was conservatively estimated that 5 g of phosphorus minerals can satisfy the needs of normal operation of a maximum of 200 cm(3) bioreactor at a chromium load of 40 mg/(L center dot d), and further analysis was performed for operating characteristics and microbial community along the route and the reactor. The results of this study provide new insights and empirical support for the in-situ bioremediation reinforcement of Cr(VI)-contaminated groundwater.
This study presents a sustainable pathway for fractionating corn stover to produce glucose, high-quality lignin nanoparticles (LNPs), and levulinic acid (LA) based on the use of p-toluenesulfonic acid (p-TsOH), a solvent having strong acidity and surface activity at a high concentration. At a moderate pretreatment temperature (100 degrees C), 85\% of xylose, 88\% of arabinose, and 83\% of lignin were removed from the substrate and present in the hydrolysate, while the cellulose yield in the solid residue fraction was 93\%. The cellulose fraction exhibited much reduced ``biomass recalcitrance{''
AimsWe investigated the role of carbon and nitrogen sources in the production of cellulase and hemicellulase by Aspergillus strains. Methods and ResultsThe strains Aspergillus niger SCBM1 and Aspergillus fumigatus SCBM6 were cultivated under solid-state fermentation (SSF), with biomass sorghum (BS) and wheat bran (WB) as lignocellulosic substrates, in different proportions, along with variable nitrogen sources. The best SSF condition for the induction of such enzymes was observed employing A. niger SCBM1 in BS supplemented with peptone; maximum production levels were achieved as follows: 72h of fermentation for xylanase and exoglucanase (30007 and 3064Ug(-1) respectively), 120h for -glucosidase and endoglucanase (5490 and 4147Ug(-1) respectively) and 144h for -xylosidase (6488Ug(-1)). ConclusionsThis work demonstrated the viability of the use of BS for the production of hemi- and cellulolytic enzymes; the high concentration of celluloses in BS could be associated with the significant production of cellulases, mainly exoglucanase. Significance and Impact of the StudyThis is the first study which presents the promising use of biomass sorghum (genetically modified sorghum to increase its biomass content) as an alternative carbon source for the production of enzymes by SSF.
In this study, elementary kenaf fibres were separated from fibre bundles using two different treatments. The first involved treating with nitric acid (HNO3) while the second used a mixture of hydrogen peroxide (H2O2) and acetic acid (CH3COOH). Both treatments were successful in isolating the elementary fibres but the H2O2/CH3COOH gave a better fibre yield and required a shorter treatment time. The fibres treated with HNO3 had an average length of 0.2 mm, an aspect ratio of 15 and a defect density of 21 defects per mm. In contrast, the H2O2/CH3COOH treated fibres had a length of 2.3 mm, an aspect ratio of 179 and a defect density of 14 defects per mm. Both treatments removed lignin, pectin, and waxes. They also increased cellulose crystallinity in the fibres, especially for HNO3 treatment. However, they resulted in some oxidation of cellulose. The H2O2/CH3COOH treatment gave a substantial improvement in the thermal stability of the fibres while a marked decrease was observed for the HNO3 treatment.
Research involving lignin use is not new. For many years, the macromolecule was underestimated in its potential and burned for energy use in pulp and paper industries. However, with the advent of biorefinery on the valorization of lignocellulosic fractions, lignin is receiving greater motivation to be researched. Of the many applications, the most profitable one is its conversion into carbon fiber. Lignin- based carbon fibers can reduce the manufacturing price of this fiber to values greater than 35\%, besides using a renewable material with a highly sustainable appellation. This paper gives an overview about lignin- based carbon fiber comparing the process to current precursors, presenting different pathways on different research, pointing to the most common difficulties and assessing new findings. A gap not fully clarified yet is concerning the lignin structure and its relation to extrusion process. After isolation procedures, lignin repolymerizes in a different manner compared to when it is in its natural form. Some studies have shown that some organic functions, the molecular weight and the structure conformation of the lignin can favor or disfavor thermal mobility. Although it is known purification is considered a criterion that favors extrusion, there is no study involving a selection of parameters that improves thermal mobility. Herein, it is highlighted a set of desired structure properties that provides a very good thermal mobility and extrusion in order to obtain a lignin- based carbon fiber with good properties.
In this experiment, corn stover was treated with optimal combined pretreatment conditions: 2\% NaOH at 80 degrees C treated 2 h combined with initial pH 9 at the ozone concentration of 78 mg/mL treated 25 min. The effect of lignin removal rate on the enzymatic hydrolysis degree of cellulose during the treatment process was studied. At the same time, the lignin in the optimal pretreated corn stover was separated and extracted by enzymatic acidolysis, and its structure and connection were characterized. The results showed that the alkali combined with ozone pretreatment improved the enzymatic hydrolysis degree of the cellulose while exfoliating and degrading the macromolecular lignin into small molecules. The stable crosslink structure of the lignin-cellulose-hemicellulose was destroyed, and the lignocellulosic structure changed in favor of the enzymatic hydrolysis of the cellulose.
The development of lignocellulose-based bioplastic is still a challenge mainly due to their high crystallinity and extensive hydrogen bond network. Sustainable modification strategies are thus essential and vital currently. Here, we proposed a thermoplasticization process by combining carboxylation and subsequent grafting with quaternary ammonium based on electrostatic interaction. Continuous steam exploded sisal fibers (SFs) was firstly carboxylated with periodate and sodium chlorite, and then grafted with cetyl trimethyl ammonium bromide (CTAB). A higher yield (\~{
In this study, effects of various strains from different genera - Aspergillus, Penicillium, Rhizopus, Mucor and Trichoderma - and of their multi-cultural fungal consortium on bio-pretreatment of wheat bran were investigated. The highest soluble carbohydrate content (198.8 mg/g) was released by P. chrysogenum F.00814 strain after 3-5 days of pretreatment. The combination of A. niger F.00632 and T. viride F.00795 strain resulted in 191.9 mg/g soluble carbohydrate that increased to 195.82 g/L by the consortium of A. niger NCAIM F.00632, P. chrysogenum NCAIM F.00814 and T. viride NCAIM F.00795 strains after three days. Optimal ratio of liquid to solid, pH and temperature as well as inoculum ratio were determined to be 5:1, pH 5.0, 30 degrees C and 65:25:15\% in total 10(7) conidia (of A. niger, P. chrysogenum and T. viride) per gram dry substrate, respectively. The application of fungal multi-cultures resulted in about 58.8 g soluble carbohydrate from 100 g substrate after 3 days of bio-treatment meaning our concept should work. The ethanol fermentation of bio-pretreated wheat bran was carried out using S. cerevisiae Levuline Fb and K. marxianus NCAIM Y.00959 and Z. mobilis subsp. mobilis B.01327(T) strains in both modes' mono- and multi-culture. 7.6\% v/v was the maximum ethanol content obtained after 7 days of fermentation with mash containing 20\% (w/v) initial reducing sugar when initiation with mixed cultures (S. cerevisiae and K. marxianus) and after two days the Z. mobilis subsp. mobilis B.01327(T) strain was added. These results were very promising to develop technology to produce lignocellulosic bioethanol. (C) 2019 Elsevier Ltd. All rights reserved.
Lignin is the major components limiting enzymatic hydrolysis and normally removed by acidified sodium chlorite in laboratory. However, the information on delignification kinetics and selectivity at cellular level as the reaction proceeds is limited. In this work, the dynamic removal of lignin and its monolignol in different cell types of poplar were visualized in real time by confocal Raman microscopy. At the initial stage, substantial reduction in lignin concentration was observed especially in cell corner and compound middle lamella of fiber, but the removal rate slowed down in the following process. Delignification was highly cell-selective that the vessel was the most resistant to delignification followed by ray and then by fiber. Besides, the removal behavior of lignin monomers in ray varied significantly with vessel and fiber. In the whole process, the syringyl units was more prone to being removed than guaiacyl units. This information could lead to a better understanding of the delignification process of lignocellulosic biomass by chlorite treatment.
Direct hydrolysis of a towel to glucose was investigated using microwave-assisted (MW) treatment combined with impregnation in concentrated sulfuric acid (SA) solution (51 wt\% for 30 min) before the MW treatment. The maximum glucose yield by direct hydrolysis of an untreated towel was 30.9\%, obtained at a heating temperature of 200 degrees C for 2 min. The maximum total glucose yield (from both direct hydrolysis and enzymatic hydrolysis of treated residue) was 74.2\%, attained at a microwave heating temperature of 180 degrees C for 3 min. This condition is milder than that of MW treatment without impregnation in concentrated SA (our previous study, heating temperature of 200 degrees C for 7 min required). As shown by XRD of the unimpregnated and impregnated towels (in 9 and 36 wt\% SA solution), the crystallinity index value decreased with the increase in SA concentration. Finally, 22.4 g of ethanol could be produced using the supernatant (containing glucose) and the microwave-treated residue as a carbon source forSaccharomyces cerevisiae, with less fermentation inhibition. Thus, impregnation in concentrated SA before MW treatment is effective for the production of glucose from cellulosic material and has low energy input.
With an increased awareness of health and wellness, prebiotics have received a great amount of attention recently. In this study, autohydrolyzate from hot water treatment of Miscanthus lignocellulosic biomass was evaluated for its prebiotic effect by fermentation of Lactobacillus brevis strain. The cell growth on raw autohydrolyzate-supplemented media was comparable to the sample grown on glucose until an incubation time of 24 h then gradually declined. Autohydrolyzate contains various inhibitors (25.9\% of total dissolved solids) and it was determined that dissolved lignin had a significant inhibitory effect to bacterial growth. When the autohydrolyzate was purified using a hydrophobic resin, purified autohydrolyzate exhibited high bacterial growth (cell density (OD 600) of 4.8) and high acid production (7.7 and 3.1 g/L of lactic and acetic acid, respectively), which was comparable with commercial xylooligosaccharides. In conclusion, mixed oligosaccharides in the autohydrolyzate from Miscanthus have considerable potential as a prebiotic and are comparable with commercial xylooligosaccharides derived products.
The optimization of enzymatic hydrolysis, with high solids loading, of two species of cactus pear for bioethanol production was tested evaluating the influence of surfactant Tween 80 and pretreatment with H2O and H2SO4 (1\% v/v) (50 degrees C, 150 rpm, 3 h). XRD and FTIR analyzes were performed. Afterwards, the influence of the factors cellulase (FPU g(-1)), pectinase (U g(-1)) and solids load (\% w/v), on the hydrolysis of varieties (50 degrees C, 150 rpm, 48 h), and the fermentation of the optimal point (33 degrees C, 8 h) were evaluated. The pretreatments and the Tween 80 did not increase the hydrolysis yields and Rotacional Central Compound Design indicated that the pectinase factor was not significant. The best cellulase and solids load conditions were 10 FPU g(-1) of biomass and 30\% w/v for both species. The fermentation efficiency of hydrolysates for Nopalea cochenillifera and Opuntia ficus-indica were 76.3\% and 82.8\%, respectively, showing their potential for bioethanol production.
In this study, the investigation on the effect of plastic during co-pyrolysis with biomass was carried out in a fixed reactor. Pyrolysis of neem wood bark (NB), low density polyethylene (LDPE) and their blends at different ratios was performed in order to evaluate the product distribution. The effects of reaction temperature and NB-to-LDPE blend ratio on product distribution and the chemical compositions of pyrolysis oil were examined. The co-pyrolysis of NB and LDPE increased the yield and quality of the bio-oil. The experiments were conducted under different LDPE addition percentages such as 20\%, 40\%, 50\%, 60\% and 80\%. Under the optimum experimental condition of 60\% addition of LDPE and a temperature of 450 degrees C, the maximum yield of bio-oil (64.8 wt\%) and hydrocarbon (75.2\%) was achieved with the lowest yield of oxygenated compounds. The calorific value of the co-pyrolysis oil was found to be higher than that of the NB pyrolysis oil. The relationship between NB and LDPE during co-pyrolysis was validated with the help of gas chromatography-mass spectrometry (GC-MS) analysis, which showed decreased oxygenated compounds.
Efficient lignocellulosic fractionation and conversion into platform chemicals provide a considerable opportunity for the industrial operation of a lignocellulosic biorefinery. However, single-step pretreatments are often insufficient to overcome biomass recalcitrance as the existence of insoluble lignin generally restricts component fractionation and conversion. This study performed a two-step pretreatment, consisting of sequential liquid hot water (LHW) and green-liquor (GL), for bioprocessing of aspen biomass into bioproducts such as glucose, lev-ulinic acid (LA), and lignin adsorbent. The two-step pretreated glucan-rich solid displayed high cellulose accessibility, which is responsible for 94\% of the glucose yield. The optimized LHW pretreatment (200 ?, 40 min) solubilized 91\% of the hemicellulose, which together with monomeric sugars in the hydrolysate solution was straightly heated at 190 ? for 80 min and yielded 72.49\% of LA in the presence of sulfuric acid as a catalyst. Moreover, GL post-treatment (Na2CO3+Na2CO3) solution maximized the delignification at 78\% from LHW pretreated substrate. The isolated lignin possessed a remarkable ability for Cd2+ and Pb2+ uptake with maxi-mized adsorption values of 250 mg/g and 228 mg/g, respectively. Finally, energy analyses showed that moderate lignocellulosic conversion could obtain an energy recovery of 85\%, providing a sustainable pathway for bio-refinery approaches.
gamma-Valerolactone (GVL), a biomass-derived green chemical, offers an environmentally responsible solvent for conversion of lignocellulose to high value-added chemicals. Herein, we report a two-step process for directly producing cellulosic residual, furfural and lignin from Miscanthus x giganteus (M. x giganteus) bypassing the isolation of xylose, which exhibits promising advantage in energy reduction. The optimized pretreatment (100 mM FeCl3 at 160 degrees C for 60 min) induced significant xylan removal (98.4\%), resulting in rugged fibre surface, thus leading to the peak cellulose conversion of 99.3\%. Furfural yield in the second step reached to 76.6\% after 100 mM FeCl3 catalyzed GVL/H2O treatment at 180 degrees C for 10 min without addition of any chemical. The extracted lignin showed representative structure (such as 13-O-4', 13-13' linkages) and medium molecular weight (4275.5 g/mol). 79.6\% of furfural can be recovered by distillation. This study proposes a systematic and energy efficient approach for maximizing biomass utilization.
Air artificially contaminated with increasing concentrations of benzene was treated in a laboratory scale compost-packed biofilter for 240 days with a removal efficiency of 81-100\%. The bacterial community in the packing material (PM) at different heights of the biofilter was analysed every 60 days. Bacterial plate counts and ribosomal intergenic spacer analysis (RISA) of the isolated strains showed that the number of cultivable aerobic heterotrophic bacteria and the species diversity increased with benzene availability. Identification of the isolated species and the main bands in denaturing gradient gel electrophoresis (DGGE) profiles from total compost DNA during the treatment revealed that, at a relatively low volumetric benzene load (1.2 <= VBL <= 6.4 g m(PM)(-3) h(-1)), besides low G+C Gram positive bacteria, originally present in the packing compost, bacteroidetes and beta- and gamma-proteobacteria became detectable in the colonising population. At the VBL value (24.8 g m(PM)(-3) h(-1)) ensuring the maximum elimination capacity of the biofilter (20.1 g m(PM)(-3) h(-1)), strains affiliated to the genus Rhodococcus dominated the micro. ora, followed by beta-proteobacteria comprising the genera Bordetella and Neisseria. Under these conditions, more than 35\% of the isolated strains were able to grow on benzene as the sole carbon source. Comparison of DGGE and automated RISA profiles of the total community and isolated strains showed that a complex bacterial succession occurred in the reactor in response to the increasing concentrations of the pollutant and that cultivable bacteria played a major role in benzene degradation under the adopted conditions.
Biofuel production is currently focused on the utilization of polysaccharides in lignocellulosic biomass. In this research, butanol was produced from sodium hydroxide-pretreated bamboo by a co-culture with the wood-rotting fungus Phlebia sp. MG-60-P2 and bacterium C. saccharoperbutylacetonicum. The bacterial monoculture could not utilize the pretreated bamboo, but the co-culture with P2 was successful. Co-culturing produced 0.5 g/L butanol, 1.3 g/L butyric acid, and 0.3 g/L ethanol from 20.0 g/L bamboo pretreated with 5.0\% NaOH. The co-culture not only gave the biofuel products but also enhanced the total saccharification rate of polysaccharides in the pretreated bamboo. A combination of 1.0\% NaOH pretreatment with the co-culture succeeded in the highest theoretical conversion (46.1\%) of carbon (in moles) from the polysaccharides to the fermentation products. This is the first report on the synergistic effects of white-rot fungus Phlebia sp. MG-60-P2 and anaerobic bacterium C. saccharoperbutylacetonicum in a co-culture to metabolize cellulose and hemicellulose in sodium hydroxide-pretreated lignocellulose to produce butanol.
The efficient reuse of agricultural wastes such as apple pomace has always been a research focus because it increases the economic added value of apple pomace and reduces environmental pollution. Using cellulose, the main component of apple pomace, is an important way to reuse apple pomace resources. Cellulose is widely used as a good adsorption material to remove dyes from water. However, the effective adsorption sites of cellulose are few, and the binding force between adsorption functional groups and dyes is weak, resulting in the unsatisfactory adsorption performance of cellulose. To solve these problems, first, cellulose from apple pomace was oxidized to easily modified dialdehyde cellulose (DAC), and a series of factors was optimized to obtain DAC with high aldehyde content. Second, an HPEI-DAC hydrogel with a three-dimensional porous structure characterized by FTIR, XPS and SEM was prepared by crosslinking hyperbranched polyethyleneimine (HPEI) containing many amine groups with DAC. Because of its special topological structure and increasingly stronger adsorption sites, the HPEI-DAC hydrogel exhibited good adsorption performance for methyl orange (MO). The effects of the DAC/ HPEI ratio, synthesis temperature, pH value and HPEI-DAC dosage on the adsorption property of HPEI-DAC for MO were studied. The HPEI-DAC hydrogel exhibited an adsorption capacity as high as 416.72 mg/g for MO. For the MO adsorption process, the adsorption kinetics and equilibrium data were consistent with the pseudo-second-order and Langmuir isotherm models, respectively. Moreover, the HPEI-DAC hydrogel could be easily regener-ated and showed good reusability. After six cycles of adsorption/desorption, the adsorption capacity of the HPEI-DAC hydrogel remained at the initial value of 70 \%. Therefore, the HPEI-DAC hydrogel can be considered a good adsorption material for treating azo dye wastewater.
Acidic aqueous ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate/acetic acid in combination with a metal salt (FeCl3) pretreatment was investigated for the pretreatment of Napier grass. This research focused on the effects of the FeCl3 concentration (20-100 mM), pretreatment time (10-190 min), and temperature (40-160 degrees C) during the pretreatment under microwave irradiation on the obtained total sugar yield after subsequent enzymatic hydrolysis. The optimum condition of these variables was determined by response surface methodology and compared with acidic aqueous IL pretreatment. The untreated and different pretreated NG samples were characterized using X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analyses. The effect of the type of anti-solvent (biomass regenerated solvent) on the obtained total reducing sugar yield by enhancing the cellulose content in the pretreated biomass was also studied. The results showed that an acidic aqueous IL could remove more lignin than the other pretreatments. The addition of FeCl3 in the acidic aqueous IL pretreatment had a significant effect on the total reducing sugar yield.
A stirred tank bioreactor (STR) coupled with two column bioreactors (CRs) was used for ethanol production from sweet sorghum stem juice by Saccharomyces cerevisiae SSJ01KKU in a very high gravity fermentation. The effects of the medium circulation rate between the STR and CRs (2.6 and 5.2 mL/min, corresponding to 25 and 50 \% of the S. cerevisiae specific growth rate), the starting time of medium circulation (0 and 4 h) and cell inoculation were investigated. The results showed that a medium circulation rate of 5.2 mL/min, starting the medium circulation at the beginning of fermentation (0 h) with cell inoculation into the STR only were appropriate conditions for ethanol production. This yielded an average ethanol concentration (PE) of 120.96 g/L and ethanol productivity (QP) of 2.52 g/L.h. When a repeated-batch (RB) ethanol fermentation in the STR coupled with CR was carried out using a drain and fill technique at different volumes (75 and 90 \%, referenced as RB1 and RB2, respectively), it was found that at least eight successive cycles could be operated under both RB1 and RB2. The average PE and QP for RB1 and RB2 were not significantly different. However, the average total ethanol production rate in RB2 (3.25 g/h) over the eight cycles was significantly higher than that of RB1 (2.60 g/h).
This study describes the application of new and low cost biosorbent, shells of urucum (Bixa Orellana), for removal of lead ions (Pb(II)) from water solution. The urucum shells were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy techniques. Batch adsorption experiments were performed in order to evaluate the effect of pH, agitation speed, adsorbent dosage, contact time, temperature, presence of interfering ions and matrix effect on the adsorption of process. The kinetics of biosorption followed pseudo-second-order model. Langmuir and Freundlich isotherm models were applied to describe the biosorption of Pb(II) by urucum shells. The Langmuir model showed better fit and the estimated biosorption capacity was 43.6 mg g(-1). The negative Gibbs free energy, Delta G degrees, confirms the spontaneous nature and positive value of enthalpy, Delta H degrees, the endothermic character of the process. Furthermore, we also performed an evaluation of matrix and others ions effect on the biosorption process.
This study assessed the performance of a Crambe abyssinica Hochst seed by-product as biosorbent for removing lead {[
Waste management in the agricultural sector has become a major concern. Increased food production to satisfy the surge in population has resulted in the generation of large volumes of solid waste. Agro-waste is a rich source of biocompounds with high potential as a raw material for food packaging. Utilization of agro-waste supports the goal of sustainable development in a circular economy. This paper reviews recent trends and the development of agro-wastes from plant and animal sources into eco-friendly food packaging systems. Different plant and animal sources and their potential development into packaging are discussed, including crop residues, process residues, vegetable and fruit wastes, and animal-derived wastes. A comprehensive analysis of the properties and production methods of these packages is presented. Future aspects of agro-waste packaging systems and the inherent production problems are addressed.
In this work, we evaluate the production of nanocellulose from yerba mate sticks (YMS) using soft chemical and steam explosion treatments. The nanocellulose is characterized by chemical characterization, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The main results showed that after the chemical treatment and steam explosion, the YMS fiber reached diameters of 11-15 nm and aspect ratios (L/D) of 12-24. The XRD results showed that there is an increase in the index of crystallinity of up to 35\% when compared to raw YMS. We discover that it is possible to obtain cellulose nanofibers (CNF) from the YMS without the use of alkaline treatment, which reduces the generation of liquid waste. Thus, the production of CNF by means of acid hydrolysis, bleaching and steam explosion represents an alternative route.
In this study, nanocrystalline cellulose (NCC) resulting from sulfuric acid hydrolysis of wood cellulose fiber, was rendered cationic by grafting with glycidyltrimethylammonium chloride (GTMAC). An optimization of the reaction parameters, such as water content, reactant mole ratio, and reaction media was performed. The presence of cationic GTMAC on the surface of NCC was confirmed by Fourier Transform Infrared Spectroscopy (FTIR). The cationically modified NCC was characterized by surface charge density, degree of substitution, potential, and particle size. It was found that the cationic surface charge density of NCC can be increased by controlling the water content of the reaction system. Surface cationization of NCC led to an increase in the surface charge density over the un-modified NCC. The cationically modified NCC was well dispersed and stable in aqueous media due to enhanced cationic surface charge density. Transmission electron microscopy (TEM) images showed the improvement in state of dispersion of canonically modified NCC over the un-modified NCC. The optimum water content was found to be 36 wt\% for aqueous based media and 0.5 water to DMSO volume ratio for aqueous-organic solvent reaction media. The increased surface charge density of NCC also delayed the onset of gelation in aqueous system. (C) 2012 Elsevier Ltd. All rights reserved.
The massive accumulation of solid wastes has brought great pressure to the environment. Most of them are pozzolanic materials, which can reduce the waste of resources by partially replacing cement in the cementitious system. The scientific and accurate activity evaluation is one of the keys to improve their utilization. Pozzolanic materials are solid wastes containing a large amount of highly active SiO2 and Al2O3 , which have wide variety and different properties. It can react with Ca(OH)2 at room temperature to produce hydraulic products con-taining silicon or aluminum. The stronger its activity is, the more suitable it is for application in cement systems. Reasonable utilization of pozzolanic materials is an important way to realize the environmental friendliness and efficient application of concrete. This paper introduces the activity evaluation methods of pozzolanic materials mainly used in cement concrete from the macro and micro aspects, points out the applicability and shortcomings of the existing methods, analyzes the mechanism of activity change, and provides a scientific and reasonable reference for the efficient utilization and in-depth research of pozzolanic materials. In addition, tips and sug-gestions are put forward for the main problems existing in the existing evaluation methods. The paper will provide a good guidance for the application of large amount of solid waste in cement system, which conforms to the concept of sustainable development.
This study analyzes the feasibility of using high-carbon content rice husk ash waste generated from open air burning of rice husk, as secondary raw materials in the manufacture of cement blocks. Solid masonry blocks having the size of 215 mm x 105 mm x 65 mm, were cast with the mix proportion of 1: 5 cement and sand. Blocks were manufactured with two types of rice husk ash (RHA); low-carbon content RHA and high-carbon content RHA. Cement blocks, at four different RHA replacement levels of 5\%, 10\%, 15\% and 20\% were prepared for low and high-carbon RHA as partial cement replacement. Testing was included for workability (water/binder ratio and setting time), strength (compressive, flexural bending and splitting tensile) and durability (water absorption, sorption, acid attack resistance and alkaline attack resistance). Results from this test results indicate that the workability, mechanical and durability characteristics of low-carbon RHA cement blocks slightly better than that of high-carbon RHA cement blocks. However, both RHA replacement cement blocks satisfy the limit recommended by standards. Even, high-carbon RHA replacement cement block does not vastly improve the strength or durability properties, the economic and environmental benefits encourage to use high-carbon RHA in cement block production.
There is increasing interest in developing biobased alternative jet fuels to meet rising aviation demand and address environmental concerns. Uncertainty of oil prices, issues of energy security, and rising greenhouse gas concentrations have spurred the development and acceptance of alternative, economically viable, environmentally sustainable production pathways. The objectives of this study were to review alternative jet fuel feedstock candidates and relevant conversion data to provide a baseline of information to be accessed and built upon in developing production scenarios in Hawai'i and other tropical regions bounded by the Tropic of Cancer in the northern hemisphere and the Tropic of Capricorn in the southern hemisphere. Seventeen plants that produce oil, fiber, and sugar feedstocks were identified, and information on cultural practices, yield ranges, invasiveness, and mechanization status was assembled. Available data on pretreatment requirements and conversion processes for the 17 feedstocks, including mass and energy balances, product and byproduct yield and quality, and scale requirements/unit sizes, were reviewed. This effort seeks to inform the development and design of alternative jet fuel production along regional supply chains in Hawai'i and other locations in the tropics.
A process has been validated for the deconstruction of lignocellulose on a pilot scale installation using six types of biomass selected for their sustainability, accessibility, worldwide availability, and differences of chemical composition and physical structure. The process combines thermo-mechano-chemical and bio-catalytic action in a single twin-screw extruder. Three treatment phases were sequentially performed: an alkaline pretreatment, a neutralization step coupled with an extraction-separation phase and a bioextrusion treatment. Alkaline pretreatment destructured the wall polymers after just a few minutes and allowed the initial extraction of 18-54\% of the hemicelluloses and 9-41\% of the lignin. The bioextrusion step induced the start of enzymatic hydrolysis and increased the proportion of soluble organic matter. Extension of saccharification for 24 h at high consistency (20\%) and without the addition of new enzyme resulted in the production of 39-84\% of the potential glucose. (C) 2016 Elsevier Ltd. All rights reserved.
Owing to the depletion of natural resources, new alternative materials are emerging in construction industry. Especially, development of alternative binders and aggregates using industrial by-products paves way for the development of eco-friendly concrete. As aggregates occupy about 60-70\% of the volume of concrete, new alternative materials developed as a substitute for aggregates are considered as need of the day for achieving sustainability in concrete industry. In the past few decades, many industrial by-products are researched as an alternative for natural aggregates. Ash being the largely produced by-products from different industries, it has huge potential in the development of artificial aggregates. Nevertheless, ashes produced from different sources such as coal, municipal solid waste and biomass have different characteristics and affect the properties of aggregates made out of them. The volume of research works reported on development of ash aggregates all over the globe shows that there is a faster growth rate in the development of alternative aggregates and its utilization in concrete. In this context, the current study aims to review the literature reported on mortar/concrete made of ash aggregates from various sources such as thermal power stations, biomass and municipal solid waste incinerator. The characteristics of different types of ash, development of aggregate and its properties in mortar/concrete are reviewed. Based on the review, future recommendations and directions are provided to utilize more of ash aggregates in the place of natural aggregates to prevent depletion of natural resources.
Lignocellulosic biomass (LCB) stands out as an abundant, inexpensive, and promising renewable source of energy that can be used to produce fuels and value-added products. LCB comprises of majorly 3 components: cellulose, hemicellulose, and lignin. These three components can be further transformed into commercially viable and sustainable products like ethanol, xylitol, acetic acid, glutamic acid, glucuronic acid, succinic acid, and vanillin and thus can contribute significantly towards developing cost-effective integrated biorefineries. Among these, xylitol has been a tremendously increasing area of interest. With having no petrochemical alternative, xylitol turns out to be one of the highest valued products which may be produced by utilizing lignocellulosic biomass. Its large-scale production is still carried out through chemical route by dehydrogenation of xylose under high pressure and temperature. Biotechnological route is the potential substitute for chemical route as it involves milder process conditions and can utilize both industrial and agricultural wastes thereby reducing the overall production cost. However, biological scheme has not been adopted yet at the industrial scale. This review focusses on the recent advances in production of xylitol using yeasts. Special emphasis is given on pretreatment and detoxification methods, critical growth parameters, various fermentation strategies, metabolic engineering, and product recovery.
Protective action of lignin/hemicellulose networks and crystalline structures of embedded cellulose render lignocellulose material resistant to external enzymatic attack. To eliminate this bottleneck, research has been conducted in which advanced proteomic techniques are applied to identify effective commercial hydrolytic enzymes. This mini-review summarizes researches on lignocellulose-degrading enzymes, the mechanisms of the responses of various lignocellulose-degrading strains and microbial communities to various carbon sources and various biomass substrates, post-translational modifications of lignocellulose-degrading enzymes, new lignocellulose-degrading strains, new lignocellulose-degrading enzymes and a new method of secretome analysis. The challenges in the practical use of enzymatic hydrolysis process to realize lignocellulose biorefineries are discussed, along with the prospects for the same.
The potential of least explored Sorghum durra as a feedstock for enzymatic saccharification in bioethanol production was evaluated as only one report is available. The pretreatment specific, optimization of saccharification of Sorghum durra stalk (Sds) was carried out. The concentrations of crude recombinant endoglucanase (BaGH5UV2), cellobiohydrolase (CtCBH5A) and beta-glucosidase (CtGH1) in cocktail were optimized for saccharification of acid or base pretreated Sds by using mixture design approach. Optimized percentage ratio of BaGH5-UV2, CtCBH5A and CtGH1 with total enzyme loading 2000 U/g of pretreated Sds for acid pretreated Sds was 43.1:10.0:46.9 and for base pretreated Sds was 80:10:10 at 48 h of saccharification. The base pretreated Sds showed 1.8-fold (165.6 mg/g of pretreated Sds) higher total reducing sugar (TRS) yield and 1.2-fold (81.7 mg/g of pretreated Sds) higher glucose yield than acid pretreated Sds. This low sugar yield from acid pretreated Sds was due to the presence of higher acid insoluble lignin content, 11.9 \% (w/w) than the base pretreated biomass (2.2 \%, w/w). In acid pretreated Sds, ANOVA data showed 3.7-fold higher F value (111.58) for BaGH5-UV2 and CtGH1 interaction than the base pretreated Sds. This indicated that the synergism between BaGH5-UV2 and CtGH1 for acid pretreated Sds was significantly higher. This was due to lower intact hemicellulose content (10.6 \%, w/w) in acid pretreated Sds than base pretreated Sds (21.8 \%, w/w). The optimized enzyme ratios for saccharification of acid pretreated Sds gave maximum TRS and glucose yield at 72 h, 113 and 85 mg/g of pretreated Sds, respectively, unlike base pretreated Sds at 96 h, 211 and 174 mg/g of pretreated Sds, respectively. These results showed that the ratio of cellulase enzymes in cocktail and their synergism depends on the type of pretreatment used for biomass. Thus, this in-house cocktail design specific to pretreatment can improve the biomass saccharification at large scale.
Oil palm frond (OPF) is a promising feedstock for the second-generation biofuel. However, the recalcitrant lignin layer conceals the cellulose component in the OPF and thus, curtails the conversion of cellulose to the value-added chemicals. The ozonolysis pretreatment is envisaged as an effective method for lignin degradation. This study investigated the influence of OPF particle size, moisture content, reaction time, ozone flowrate as well as their interaction, on lignin degradation and total reducing sugar (TRS) recovery by response surface methodology (RSM). The experiments conducted were based on Box-Behnken design (BBD). The process condition for the optimum lignin degradation and TRS recovery was determined by desirability function. The RSM analysis revealed that the interaction of particle size-moisture content was important for the lignin degradation while the interaction of moisture content-reaction time during ozonolysis was crucial for TRS recovery. Both the lignin degradation and TRS recovery at 84.7 wt.\% and 99.9\%, respectively were optimized simultaneously under the recommended optimum conditions. The pre-treated OPF under the optimum conditions yield the levulinic acid equivalent to the commercial cellulose. (C) 2016 Elsevier B.V. All rights reserved.
Lignocelluloses are often a major or sometimes the sole components in different waste streams from various sources such as industries, forestry, agriculture and municipalities. It represents an as-of-yet untapped source of fermentable sugars for significant industrial use. Many physico-chemical, structural and compositional factors hinder the hydrolysis of components present in the biomass to sugars and other organic compounds that can later be converted into fuels. During the past few years, a large number of chemical pretreatment methods including lime, acid, steam explosion, sulfur dioxide explosion, ammonia fiber explosion, ionic liquid and others have been developed for efficient pretreatment of biomass. Many pretreatment methods have shown high sugar yields i.e. more than 90\% of the theoretical yield from lignocelluloses. In this review, we discuss various chemical pretreatment processes, feasibility of the processes at industrial scale in terms of the mechanisms involved, advantages, disadvantages and economic assessment. It is not possible to define the best pretreatment method as it depends on many factors such as type of lignocellulosic biomass, process parameters, environmental impact, economical feasibility, etc. However, some of these chemical pretreatments have disadvantages such as formation of inhibitory compounds especially furfural and 5-hydroxyl methyl furfural (HMF). (C) 2014 Elsevier Ltd. All rights reserved.
This study investigated how various hemicellulosic fractions extracted from corncob, which have different chemical structures, affect paper strength properties when derivatized and used as paper strengthening agents. Four hemicellulosic fractions with different molecular weights and heteropolymer branching were extracted from corncob via a selective precipitation process; afterwards, the fractions were then chemically modified to obtain cationic hemicelluloses, which were used as strengthening agents for recycled pulp papermaking. These cationic hemicellulosic fractions improved the mechanical strengths of handsheets composed of recycled fibers and paper machine white water fines; however, the level of improvement was different among the fractions. Cationic hemicellulosic fractions showed a better improvement on the strength of handsheets without fines than that of the handsheets with fines. Especially, cationic hemicellulosic fraction obtained from 30\% ethanol aqueous medium had the highest molecular weight and the highest substitution degree and thus showed the best enhancement in the mechanical strength of handsheets. Hence, this work demonstrates how to utilize hemicelluloses efficiently as strength agents for recycled pulp papermaking.
Second generation ethanol from lignocellulose materials has been used in applications for food processing wastes. Since Brazil has a leading position in orange juice exports, the influence of acid and alkali pretreatments on liquor saccharification, solubilization of solid fraction and mass yield was evaluated. Time and C-acid or C-alkaline at different concentrations of solids (low to moderate, 1 to 9\%) and high catalyst concentrations were analyzed. A hydrothermal pretreatment was conducted under the same conditions of acid and alkaline treatments to investigate the relative selectivity increase in using the catalysts. The chemical analyses of wastes indicated a 70\% total carbohydrate level denoting a promising raw material for bioethanol production. Pretreatment caused acid saccharifications between 25 and 65\% in total reducing sugars (TRS) and mass yields (MY) between 30 and 40\%. In alkaline pretreatment, these rates ranged between 2 and 22.5\% and between 30 and 80, respectively. In hydrothermal pretreatment, solubilized TRS varied between 3 and 37\%, whereas MY remained between 45 and 60\%, respectively. C-biomass strongly influenced the three variables; in the same way, time affected MY.
A new xylan ester (xylan 3,5-dinitrobenzoate) as a creatinine adsorbent was prepared by the homogeneous acylation of xylan with 3,5-dinitrobenzoyl chloride in 1-butul-3-methylimidazolium chloride ionic liquid. The influences of reaction conditions on the degree of substitution values of xylan esters were discussed. Results indicated that xylan esters with the degree of substitution range from 1.34 to 1.77 were obtained under the given conditions. The FIR and C-13 NMR spectroscopies provided the evidence of grafting 3,5-dinitrobenzoyl groups onto the backbone of xylan. Moreover, the adsorption properties of the xylan ester for creatinine were also investigated. Isotherm studies showed that the sorption capacities for creatinine were 2.45, 2.08 and 1.86 mg/g for 23, 30 and 37 degrees C, respectively. Thermodynamic studies performed indicated the sorption process mainly was controlled by the chemical adsorption. Therefore, xylan 3,5-dinitrobenzoate displayed the promising application in the treatment of chronic renal failure by the creatinine adsorption as the new oral adsorbent. (C) 2015 Elsevier Ltd. All rights reserved.
An integrated pretreatment that realizing effective fractionation and targeted valorization can guarantee the implementability to future biorefinery scenario. In the present study, a stepwise approach using acetic acid-catalyzed hydrothermal pretreatment (AAP) and rapid ball-milling process was successfully developed for pro-ducing high-yield of xylo-oligosaccharides (XOS), fermentable glucose and native lignin from poplar wood. It was found that the AAP removed the most hemicelluloses, releasing the highest yield (36.16\%) of XOS at 160 degrees C for 1 h. Subsequent rapid ball-milling pretreatment for 10 min led to a remarkable increase in the saccharifi-cation efficiency from 40.68\% to 91.35\%. Meanwhile, the residual lignin fractions exhibited abundant beta-O-4 linkages, which are beneficial to catalytic hydrogenolysis of these lignin fractions into the aromatic chemicals. Considering the integrated process could effectively produce XOS, fermentable glucose, and the residual lignin with well-preserved structures, the proposed process is a promising and efficient deconstruction strategy in current biorefinery scenario.
Abundant biomass is a potential energy source. However, it possesses several challenges when considered for energy applications. Torrefaction, a thermal pretreatment process can improve the properties of biomass as energy source. This study focused on comparing effect of torrefaction operating parameters on agricultural and wood wastes properties as fuel. The physiochemical properties, composition, moisture-biomass interaction and ash melting behavior were determined. The result show that higher torrefaction temperature and longer residence time increased lignin content, reduced hemicellulose and cellulose content. The moisture uptake of torrefied biomass was reduced in the range 2.47-9.94\% compared with raw biomass depending on torrefaction temperature that indicate torrefied biomass was more hydrophobic than raw biomass. The moisture adsorption isotherm curve shows type II isotherm based on the Brunauer-Emmett-Teller's (BET) classification and was best described by the Oswin model. In addition, torrefaction treatment showed significant influence on the melting behavior of the biomass ash. Especially for agricultural wastes, the fouling tendency shifted from serious range to low range with torrefaction treatment. Torrefaction showed promise for improving fuel characteristics of the studied biomass.
Cellulose nanocrystals (CNCs) are attractive for use in polymer composites, biomedical applications, and barrier packaging. In all of these applications they are mixed with other components and compatibility is a major design consideration, as CNCs naturally have a high density of surface hydroxyl groups and primarily disperse well in polar media. Numerous surface modification approaches have been used to address these issues, but challenges remain due to the variability in the commercially available CNC materials. CNCs can be produced from biomass using several extraction methods, most notably acid hydrolysis and biomass extraction, also known as the American Value Added Pulping process. The production method of the CNC material has an impact on both physical and surface properties of CNCs, including size, shape, crystal structure, and zeta potential. In addition, post-treatments can be used to purify the CNC material and further alter these properties. This work studies the properties of CNCs from three different commercial suppliers and after conducting three different post-treatments: dialysis, Soxhlet extraction, and acetone washing to understand the effect of the commercial source and purification on CNC surface properties and modification via 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) mediated oxidation. We show that there is significant variation in CNC physical and surface properties between different commercial suppliers before and after purification. Importantly, we show that for CNCs produced through acid hydrolysis, acetone washing or Soxhlet extraction in ethanol decreases the achievable degree of TEMPO modification, but makes it more consistent between the different commercial suppliers. This has important implications for improving reproducibility in CNC research as well as aiding the expanding fields of applications.
The global economy growth requires a sustainable management of agro-industrials and by-products, as they represent a source of bioactive compounds (BCs) (such as antioxidants and carbohydrates) with relevant biotechnological and nutritional value. Their use is potentially applicable to different fields, as it can provide an added value to food products, such as shelf-life improvement. Moreover, according to the ``Zero{''
The pulp and paper industry growingly paid attention to the recycling and maintenance of waste paper products. Each paper-making cycle would lead to a sharp drop in the mechanical properties of the cellulosic paper, which was related to the hornification effect. Here, the recycling performance of the holocellulose paper was studied, compared with that of the cellulosic paper. Holocellulose fibers from sisal were fabricated by a gentle delignification method, and the well-preserved cellulose and hemicellulose components hindered the cocrystallization and aggregation of cellulose fibril. Holocellulose paper exhibited much more favorable recycling properties, compared with cellulosic paper. After 5 runs of recycling, holocellulose paper still shown an ultimate strength as high as 25 MPa (reduced from 35 MPa), a decrease of 28.6\%. However, cellulosic paper experienced a substantial loss in ultimate strength from 35 MPa to 9 MPa, a decrease of about 74.3\%. This can be attributed to the coreshell structure from cellulose and hemicellulose to weaken the hornification effect.
Biofuel derived from halophytic biomass is getting attention owing to the concerns of energy versus food crisis. The disadvantages associated with edible bioenergy resources necessitate the need to explore new feedstocks for sustainable biofuel production. In this study, biomass from locally available abundant halophytes (Panicum antidotale, Phragmites karka, Halopyrum mucronatum, and Desmostachya bipinnata) was screened for saccharification by an enzyme cocktail composed of cellulase, xylanase, and pectinase from Brevibacillus borstelensis UE10 and UE27, Bacillus aestuarii UE25, Aneurinibacillus thermoaerophilus UE1, and Bacillus vallismortis MH 1. Two types of pretreatment, i.e., with dilute acid and freeze-thaw, were independently applied to the halophytic biomass. Saccharification of acid-pretreated P. karka biomass yielded maximum reducing sugars (9 mg g(-1)) as compared to other plants. Thus, the factors (temperature, pH, substrate concentration, and enzyme units) affecting its saccharification were optimized using central composite design. This statistical model predicted 49.8 mg g(-1) of reducing sugars that was comparable to the experimental value (40 mg g(-1)). Scanning electron microscopy and Fourier-transform infrared spectroscopy showed significant structural changes after pretreatment and saccharification. Therefore, halophytes growing in saline, arid, and semi-arid regions can be promising alternative sources for bioenergy production.
Succinic acid is a valuable bulk chemical, which has been extensively applied in food, medicine, surfactants and biodegradable plastics industries. As a substitute for chemical raw material, bio-based succinic acid production has received increasing attention due to the depletion of fossil fuels and environmental issues. Meanwhile, the effective bioconversion of lignocellulosic biomass has always been a hot spot of interest owning to the advantages of low expense, abundance and renewability. Consolidated bioprocessing (CBP) is considered to be an alternative approach with outstanding potential, as CBP can not only improve the product yield and productivity, but also reduce the equipment and operating costs. In addition, the current emerging microbial co-cultivation systems provide strong competitiveness for lignocellulose utilization through CBP. This article comprehensively discusses different strategies for the bioconversion of lignocellulose to succinic acid. Based on the principles and technical concepts of CBP, this review focuses on the progress of succinic acid production under different CBP strategies (metabolic engineering based and microbial co-cultivation based). Moreover, the main challenges faced by CBP-based succinic acid fermentation are analyzed, and the future direction of CBP production is prospected.
Properties of cellulosic materials, such as average molar mass (MMvis), crystallinity index and hemicelluloses content may influence the efficiency of the enzymatic conversion of cellulose to glucose. Studies on the simultaneous influence of these parameters have been scarcely found in the literature. In the present study, the conversion of cellulose to glucose was investigated using cellulosic materials with different MMvis, crystallinity, and hemicelluloses content: microcrystalline cellulose (MCC, MMvis = 22104 g mol(-1), CI = 79\%, no hemicelluloses detected), sisal pulp (SP, MMvis = 94618 g mol(-1), CI = 66\%, hemicelluloses content = 2.6\%) and filter paper (FP, MMvis = 98530 g mol(-1) CI = 63\%, hemicelluloses content = 19.2\%). During the reactions, aliquots were withdrawn and, in addition to the liquors, the unreacted cellulosic materials were evaluated by MMvis, CI, SEM, length and thickness, which can help further understand the reaction as a whole. The liquors were characterized by high-performance liquid chromatography (HPLC) and Miller's method (or DNS). The highest yield for the conversion of cellulose to glucose was observed for SP (88\%), followed by MCC (64\%) and FP (52\%). The results indicated that the presence of high hemicelluloses content (FP) had a more significant interference effect than high crystallinity (MCC).
Xylooligosaccharides (XOS) are useful food and pharmaceutical additives, which can be produced from various xylans. However, the XOS prepared from lignocellulosic materials are difficult to purify due to the complexity of the degradation products. Thus, hemicelluloses with a high-purity will be the preferred feedstock for XOS production. In this work, acid hydrolysis and enzymatic hydrolysis were applied to prepare XOS from the residual hemicelluloses of the dissolving pulp. The results showed that the highest XOS yield (45.18\%) obtained from the acid hydrolysis was achieved with 1\% sulfuric acid at 120 degrees C for 60 min, and xylohexaose accounted for 47\% of the XOS. For enzymatic hydrolysis, under optimal conditions, the highest XOS yield of 42.96\% was observed, and xylobiose and xylotriose comprised 90.5\% of the XOS. It is suggested that the distribution of the XOS could be controlled significantly according to the enzymatic or acid hydrolysis conditions used.
beta-Xylosidase activity is deficient in most cellulase enzymes secreted by filamentous fungi, which limits effective enzymatic hydrolysis of hemicellulose in lignocellulose materials and resulted in accumulation of xylo-oligosaccharides that inhibit the cellulase and xylanase activitives. An endogenous beta-xylosidase gene, xyl3A, was overexpressed using two types of promoters in cellulolytic P. oxalicum RE-10. The mutants RXyl, RGXyl-1 and RGXyl-2 displayed higher beta-xylosidase production than native strain RE-10 besides higher cellulase and xylanase activities, especially RGXyl-1, showing the highest beta-xylosidase activity of 15.05 +/- 1.79 IU/mL, about 29 folds higher than native strain, more than the highest level reported by literature. Enzymatic hydrolysis results indicated the cellulase RGXyl-1 not only increased glucose and xylose yields and thus resulted in high ethanol yield during the simultaneous saccharification and fermentation, but decreased the total enzyme loading compared to starting RE-10, which indicated a good prospect of industrial application in bioconversion of lignocellulose.
This study develops a system for the efficient valorisation of hemicellulosic hydrolysates of vineshoot trimmings. By connecting two reactors of 2 L and 10 L, operational conditions were set up for the sequential production of lactic acid and xylitol in continuous fermentation, considering the dependence of the main metabolites and fermentation parameters on the dilution rate. In the first bioreactor, Lactobacillus rhamnosus consumed all the glucose to produce lactic acid at 31.5 degrees C, with 150 rpm and 1 L of working volume as the optimal conditions. The residual sugars were employed for the xylose to xylitol bioconversion by Debaryomyces hansenii in the second bioreactor at 30 degrees C, 250 rpm and an air-flow rate of 2 L min(-1). Several steady states were reached at flow rates (F) in the range of 0.54-5.33 mL min(-1), leading to dilution rates (D) ranging from 0.032 to 0.320 h(-1) in Bioreactor 1 and from 0.006 to 0.064 h(-1) in Bioreactor 2. The maximum volumetric lactic acid productivity (Q(P) (LA) = 2.908 g L-1 h(-1)) was achieved under D = 0.266 h(-1) (F = 4.44 mL min(-1)); meanwhile, the maximum production of xylitol (5.1 g L-1), volumetric xylitol productivity (Q(P xylitol) = 0.218 g L-1 h(-1)), volumetric rate of xylose consumption (Q(S) (xylose) = 0.398 g L-1 h(-1)) and product yield (0.55 g g(-1)) were achieved at an intermediate dilution rate of 0.043 h(-1) (F = 3.55 mL min(-1)). Under these conditions, ethanol, which was the main by-product of the fermentation, was produced in higher amounts (1.9 g L-1). Finally, lactic acid and xylitol were effectively recovered by conventional procedures.
The newly developed aminated maize stalk (AMS) was prepared by a chemical process using charred maize stalk (CMS). The AMS was used for the removal of nitrate and nitrite ions from aqueous media. The effects of initial anion concentration, contact time, and pH were studied by the batch method. The prepared adsorbent was characterized by , and elemental analysis. The concentration of the nitrate and nitrite solution before and after was determined with the help of a UV-Vis spectrophotometer. The maximum adsorption capacities were found to be 294.11 mg/g for nitrate and 232.55 mg/g for nitrite, respectively, at pH 5 for both ions attaining equilibrium within 60 min. The BET surface area of AMS was found to be 25.3 m(2)/g with a pore volume of 0.02cc/g. The pseudo-second-order kinetics model fit well, and the adsorption data supported the Langmuir isotherm. The findings revealed that AMS has a high capability for removing nitrate (NO3-) and nitrite (NO2-) ions from their aqueous solutions.
Pinggu Peach Orchard is one of the largest orchards in Beijing, China, providing consumers with high-quality peaches. However, a large number of discarded peach branch waste was produced along with the peach production every year, which can cause environmental pollution and have potential safety hazards since they can only be burned or stacked on the roadside or in the field. Therefore, it is important and urgent to develop recycling techniques of discarded peach branches. In this study, peach branches-cellulose nanofiber (PB-CNF) was prepared by high-pressure homogeneous (HPH) from discarded peach branches and used as a reinforcing agent to enhance mechanical performance and adsorption capacity of the gelatin hydrogel. The variations on morphological, physic-chemical, and thermal characteristics of the PB-CNF were closely related to the cycles of HPH. Rheological properties of gelatin and PB-CNF were studied to understand the viscoelastic properties as well as gelling and melting temperature of the hydrogel. The results suggested that the HPH treatment was applied to produce PB-CNF with 5 nm in diameter, low crystallinity, and uniform dispersion. PB-CNF under HPH mixed with gelatin in an appropriate ratio of 1/4 can easily obtain a stable hydrogel system, which contributed to improving the mechanical performance and adsorption capacity of the hydrogel. Therefore, the waste peach wood can be used as raw material to extract and prepare a reinforcing agent (PB-CNF).
Over the past two decades, birchwood and beechwood xylans have been used as a popular substrate for the characterization of xylanases. Recently, major companies have discontinued their commercial production. Therefore, there is a need to find an alternative to these substrates. Xylan extraction from Acacia sawdust resulted in 23.5\% (w/w) yield. The extracted xylan is composed of xylose and glucuronic acid residues in a molar ratio of 6:1 with a molecular mass of similar to 70 kDa. The specific optical rotation analysis of extracted xylan displayed that it is composed of the D-form of xylose and glucuronic acid monomeric sugars. The nuclear magnetic resonance analysis of extracted xylan revealed that the xylan backbone is substituted with 4-O-methyl glucuronic acid at the O2 position. Fourier transform infrared analysis confirmed the absence of lignin contamination in the extracted xylan. Xylanase from Clostridium thermocellum displayed the enzyme activity of 1761 U/mg against extracted xylan, and the corresponding activity against beechwood xylan was 1556 U/mg, which confirmed that the extracted xylan could be used as an alternative substrate for the characterization of xylanases.
Nanocrystalline cellulose (NCC) was produced from rice husk biomass (Oryza sativa) by a chemical extraction process to explore the potential aspect of agro-waste biomass in Australia. In this work, the delignified rice husk pulp (D-RHP) was produced by alkaline delignification of raw rice husk biomass (R-RHB) using 4 mol.L-1 alkali solutions (NaOH) in a jacketed glass reactor under specific experimental conditions. D-RHP was bleached using 15\% sodium hypochlorite, and the bleached rice husk pulp was coded as B-RHP. Finally, raw suspension of NCC was produced by the acid hydrolysis of B-RHP using 4 mol.L-1 sulphuric acid. The raw suspension of NCC was neutralized by a buffer solution and analyzed by TAPPI, FT-IR, XRD, SEM, AFM, and TEM. FT-IR spectra of NCC are different to R-RHB but similar with B-RHP and D-RHP. From XRD results, the crystallinity of NCC was found to be approximately 65\%. In AFManalysis particle thicknesses have been confirmed to be in the range of (25 +/- 15.14) nm or (27 +/- 15.14) nm which is almost the same. From TEM analysis particle dimensions have been confirmed to be in the range of (50 +/- 29.38) nm width and (550 +/- 302.75) nm length with the aspect ratio similar to 11:1 (length/diameter) at a 500 nm scale bar. On the other hand, at a 200 nm scale bar the particle dimensions have been confirmed to be in the range of (35 +/- 17) nm width and (275 +/- 151.38) nm length with the aspect ratio similar to 8:1. The aspect ratio of individual crystalline domain was determined in TEM analysis which is 10:1 (100/10). Therefore the aspect ratios and dimensions of nanoparticles in NCC suspension are almost the same and in nano-meter scale, as confirmed from both AFM and TEM results. The yield of NCC from B-RHP was found to be approximately 95\%, and the recovery of cellulose from R-RHB is about 90\%. (C) 2017 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.
The growing consumption of green coconut - fresh and industrialized - in Brazil generates a large volume of wastes and coproducts that justifies the search for alternatives for their use in animal feeding. The most limiting factor to the inclusion of these coproducts in ruminant diets is their high fiber content, which may restrict intake and performance. The present study determined the composition and in vitro dry matter degradability of whole coconut, coconut powder, and coconut fiber treated with sodium hydroxide (0\%, 3\%, and 6\%) and the effect of including whole coconut hydrolyzed with 6\% sodium hydroxide at different concentrations (25\%, 30\%, 35\%, and 40\%) in the diet on apparent digestibility of nutrients, performance, and feeding behavior of sheep. Alkalinization decreased the hemicellulose, NDF, and ADF contents of the evaluated coproducts. Whole coconut and coconut powder provided greater in vitro degradation of DM compared with coconut fiber, with highest values obtained with the inclusion of 6\% sodium hydroxide. Inclusion of whole coconut in the diets did not affect the intakes of DM, CP, NDF, and ADF, but influenced weight gain, feed conversion, and apparent digestibility of DM and NDF. Regarding the feeding behavior of the animals, the inclusion of whole coconut in the diet only affected their rumination time. Whole coconut hydrolyzed with 6\% NAOH can be included in diets for feedlot sheep at up to 35\% without reducing intake or weight gain.
Although green macro-algae represent a renewable and highly abundant biomass, they remain poorly exploited in terms of carbohydrate polymers compared to red and brown ones and other lignocellulosic materials. In this study, cellulose from the green macro-algae Enteromorpha sp. was isolated, physico-chemically characterized and enzymatically functionalized. The cellulose content was about 21.4\% (w/w). FTIR analyses indicated an absence of acetyl or uronic esters confirming the absence of hemicellulose contamination. The 36\% crystallinity index of the extracted cellulose revealed a high amorphous character as determined by X-ray diffraction. The moisture adsorption isotherms and specific surface measurements were respectively 42.87 g/100 g and 8.34 m(2)/g. The Enteromorpha sp. cellulose was first enzymatically saccharified by a commercial cellulase preparation from Aspergillus niger with a hydrolysis yield of 70.4\%. Besides, it was successfully functionalized based on the transglycosylation mechanism of the same enzymatic preparation, to produce highly added-value biosurfactants (butyl-glucoside) with a concentration of 8 mM. (C) 2015 Elsevier Ltd. All rights reserved.
Vine shoots are an agricultural waste rich in carbohydrates that can be considered as a promising energy source alternative. The objective of this work was to propose a process strategy for the valorisation of this residual biomass, including the chemical conversion of solubilised sugars into furfural and the biological conversion of cellulosic glucose into H2. Vine shoots were subjected to steam explosion pretreatment, and its operational conditions were optimised as 190 degrees C and 1.6\% H2SO4 impregnated biomass. These pretreatment conditions allowed to recover 68.2\% of the hemicellulose sugars and 18.2\% of glucose in the prehydrolysate and 45.3\% glucose by enzymatic hydrolysis. Thus, the pretreated solid obtained under optimised conditions was subjected to enzymatic hydrolysis and the slurry generated was used as a substrate by Clostridium butyricum for fermentation into biohydrogen (830.7 mL/L and a yield of 3550 mL per 100 g of raw vine shoots) and organic acids (1495.3 mg acetic acid/L and 1726.8 mg butyric acid/L). Based on furfural production, the chemical conversion of xylose in the prehydrolysate was optimised in a microwave reactor at 202 degrees C, using 0.195 M FeCl3 as a catalyst, with a furfural production of 15 g/L and 73\% yield.
The search for sustainable processes is constantly increasing in the last years, so reusing, recycling and adding value to residues and by-products from agroindustry is a consolidated area of research. Particularly in the field of fermentation technology, the lignocellulosic substrates have been used to produce a diversity of chemicals, fuels and food additives. These residues or by-products are rich sources of carbon, which may be used to yield fermentescible sugars upon hydrolysis, but are usually inaccessible to enzyme and microbial attack. Therefore, pretreatments (e.g. hydrolysis, steam explosion, biological pretreatment or others) are required prior to microbial action. Biopigments are added-value compounds that can be produced biotechnologically, including fermentation processes employing lignocellulosic substrates. These molecules are important not only for their coloring properties, but also for their biological activities. Therefore, this paper discusses the most recent and relevant processes for biopigment production using lignocellulosic substrates (solid-state fermentation) or their hydrolysates.
BACKGROUNDSteam explosion is widely used on a variety of plant biomass for the hydrolysis of hemicellulose. However, hydrolysis by steam explosion suffers from low xylose yield, long hydrolysis time and high energy consumption, which impede the xylitol fermentation step. This study used a dilute sulfuric acid pre-impregnation prior to the steam explosion to prepare corncob hemicellulose hydrolysate which offers high xylose yield for xylitol fermentation by Candida tropicalis. RESULTSAfter pre-impregnation with 0.3\% (wt) dilute sulfuric acid at a liquid to corncob ratio of 3 for 6h, corncobs were steamed at 200 degrees C for 5min to obtain a maximum xylose yield of 23.5\% in the hydrolysate. The hydrolysate was detoxified by concentrating with vacuum evaporation followed by adsorption using activated carbon. The detoxified hydrolysate was then used for xylitol fermentation. Maximum xylitol yield of 75.1\%, volumetric productivity of 2.01gL(-1)h and biomass of 20.9gL(-1) were obtained from the detoxified hydrolysate. CONCLUSIONFindings suggested that this acid pre-impregnated steam explosion strategy provides a highly effective way to prepare hemicellulose hydrolysate with high xylose yield, and could be potentially applied to industrial xylitol fermentation. (c) 2013 Society of Chemical Industry
A renewable biofuel economy is projected as a pathway to decrease dependence on fossil fuels as well as to reduce greenhouse gases (GHG) emissions. Ethanol produced on large-scale from lignocellulosic materials is considered the automotive fuel with the highest potential. In this paper, a life cycle assessment (LCA) study was developed to evaluate the environmental implications of the production of ethanol from a fast-growing short rotation crop (SRC): eucalyptus as well as its use in a flexi-fuel vehicle (FFV). The aim of the analysis was to assess the environmental performance of three ethanol based formulations: E10. E85 and E100, in comparison with conventional gasoline. The standard framework of LCA from International Standards Organization was followed and the system boundaries included the cultivation of the eucalyptus biomass, the processing to ethanol conversion, the blending with gasoline (when required) and the final use of fuels. The environmental results show reductions in all impact categories under assessment when shifting to ethanol based fuels, excluding photochemical oxidant formation, eutrophication as well as terrestrial and marine ecotoxicity which were considerably influenced by upstream activities related to ethanol manufacture. The LCA study remarked those stages where the researchers and technicians need to work to improve the environmental performance. Special attention must be paid on ethanol production related activities, such as on-site energy generation and distillation, as well as forest activities oriented to the biomass production. The use of forest machinery with higher efficiency levels, reduction of fertilizers dose and the control of diffuse emissions from the conversion plant would improve the environmental profile. (C) 2012 Elsevier B.V. All rights reserved.
Cassava starch is an abundant feedstock for biological transformation to ethanol, however, its industrial processing needs further improvements to enhance efficiency and cost-effectiveness. In the present study, a low-cost catalyst (CC-SO3H) was synthesized by partial carbonization and sulfonation of crystalline cellulose, which was thermally stable and reactive at 160 degrees C in 5 times repeated batch of thermohydrolysis of cassava starch. The catalyst was studied for its potential role in the hydrolysis of cassava starch as a standard feedstock. It was shown that the milling of cassava starch in the presence of the CC-SO3H catalyst improved the solid-state reaction that enhanced porosity, increased surface area and decreased crystallinity of the starch granules. These phenomena caused the rapid thermohydrolysis of starch with an exceptionally high starch conversion rate (96.43\%), glucose yield (93.12\%), and glucose selectivity (95.32\%) within 2h of reaction at 160 degrees C, 10 bar. The highest ethanol yield (0.43 g ethanol/g total reducing sugars) was achieved at 96 h of fermentation corresponding to the highest ethanol concentration of 15.41 g/L from the fermentation of hydrolysate of mixed-milling/thermo-hydrolysis at 160 degrees C for 2 h of cassava starch. In addition, the reaction kinetics showed the feasibility of this process for robust bioethanol production from starchy feedstocks. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Results are reported and discussed on the treatment of benzene-polluted air streams with a laboratory-scale biofilter packed with powdered compost and using an indigenous microbial consortium. Different superficial gas velocities and influent benzene concentrations were investigated to establish the optimal operational conditions. Continuous experiments were conducted over about I year with the airflow directed upwards. A maximum removal capacity of 20.1g m(packing) (-3)(material) h(-1) was achieved at a benzene-loading rate of 24.8 g m(-3) h(-1). Benzene and biomass concentrations profiles along the column indicate that the distribution of biomass depended on the pollutant mass loading and that a linear relationship existed between biomass concentration and specific elimination rate. A biofilm model incorporating zero-order kinetics was applied to interpret and characterize the process macrokinetics. At low benzene inlet concentration and superficial gas velocity, the system performance was well described by a diffusion limitation model, whereas possible reaction limitation took place under harder conditions. (c) 2004 Elsevier Ltd. All rights reserved.
To develop an efficient heterogeneous catalyst with good stability and reusability for catalytic conversion of cellulose to platform compounds, carbon foam (CF) was used to immobilize phosphotungstic acid (HPW) to prepare CF-supported HPW (HPW/CF) catalyst. Three-dimensional CF was prepared by carbonization of bread (precursor of CF) with mechanical activation (MA)-damaged starch, gluten protein, and yeast as materials. CF30 (30 wt\% of gluten protein) exhibited good mechanical strength, relatively high specific surface area, and desired hierarchical porous structure. HPW was successfully anchored onto CF30 by grafting to prepare HPW/CF30 catalyst, which could effectively catalyze the hydrolysis of cellulose to produce glucose, especially for the hydrolysis of MA-pretreated cellulose with small granules and amorphous structure. The affinity between free hydroxyl groups of MA-pretreated cellulose and oxygen-containing groups of CF30 enhanced the catalytic efficiency of HPW/CF30. In addition, HPW/CF30 catalyst exhibited good reusability and was easily separated from reaction system for recycling.
A homogeneous system for nanocellulose acetylation was investigated. Cellulose nanostructures (CNS) were obtained from microcrystalline cellulose, and modification was conducted to increase hydrophobicity and physico-chemical properties of the nanoparticles. Sulfuric acid and hydrochloric acid were used for the isolation. The CNS were characterized with dynamic light scattering, zeta potential, atomic force microscopy, Fourier-transform infrared spectroscopy, nuclear magnetic resonance, X-ray photoelectron spectrometry, degree of substitution (DS), X-ray diffraction (XRD), and thermogravimetric analysis. Nanostructures obtained with sulfuric acid showed lower particle sizes and lower thermal stability. After modification, the results indicated the substitution of OH groups in cellulose structure by acetyl groups. The XRD patter was considerably modified and it was verified that acetylation increased the thermal stability. Different methods were used to calculate the DS, and the differences between the methodologies were explained. The acetylated samples play an important role in the nanocomposites field, since the hydrophobic surface increase its applications.
The effect of sulfated (original), carboxylated (oxidized), and Jeffamines M2005-grafted cellulose nanocrystals (CNCs) on the barrier and mechanical properties of thermoplastic starch (TPS) and poly(3-hydroxybutyrate) (P(3HB)) matrices was investigated. CNCs were first oxidized via a catalytic reaction using NaClO as an oxidant and then grafted with an amine-terminated ethylene oxide (EO)/propylene oxide (PO) copolymer (Jeffamine) by an amine-acid coupling reaction. A degree of oxidation (DO) of 0.108 (mol/mol of anhydroglucose) was attempted for the carboxylated CNCs, whereas a degree of substitution (DS) of 0.04 (mol/mol of anhydroglucose) was determined for the M2005-grafted CNCs. These values indicated satisfactory reactive process, with yields of 68\% and 47.3\% for the carboxylation and peptide coupling reactions, respectively. Fourier-transform infrared spectroscopy (FTIR) analysis showed bands at 1643 cm(-1) and 1550 cm(-1) in the spectrum of M2005-grafted CNCs, which qualitatively indicated the amide bond formation. In addition, the morphology and the zeta potential of modified CNCs ensured their homogeneity, stability, and surface degree of charge. In spite of a decrease in the solubility in water of the modified crystals, the procedure of chemical modification used avoided any variation in their crystalline structure and thermal stability. Then, the incorporation of sulfated, oxidized, or M2005-grafted CNCs in matrices of TPS and P(3HB) allowed to produce reinforced nanocomposite films, with excellent barrier properties. Therefore, the chemical compatibility between CNCs and the polymer matrices is essential to produce attractive nanocomposites with improved mechanical properties for industrial applications.
Solid-state cultivations of genetically modified strains of Aspergillus nidulans A773, using soybean fibre as substrate, were carried out to produce xylanase and arabinofuranosidase, and these enzymes were subsequently used to obtain xylooligosaccharides using the same agro-residue. First, the best fungi cultivation conditions (moisture content, pH, temperature and addition of maltose) were optimized one-by-one for obtain the crude enzyme extracts. Subsequently, the application of xylanase on soybean fibre to obtain xylooligosaccharides was optimized by central composite design, defining best enzyme concentration and reaction temperature. The best condition obtained (50 degrees C and 117 U g(-1) of soybean fibre) was used to evaluate the co-production of xylooligosaccharides by the addition of different concentrations of arabinofuranosidase. The highest yield of xylooligosaccharides obtained was 28\% (mass fraction of xylan), showing final concentrations (in mg g(-1) arabinoxylan) of 138.36 xylobiose (X2), 96.96 xylotriose (X3), and 53.04 xylotetraose (X4), in 9 h enzymatic reactions. The conversion of arabino-xylans into different xylooligosaccharides suggests the potential to use recombinant A. nidulans A773 enzymes to obtain prebiotics using a sugar-rich, low-cost soybean residue.
A degrading microbial consortiumhighly tolerant to three-, four-and five-ring polycyclic aromatic hydrocarbons (PAHs) was selected from 50 fungal and bacterial isolates obtained from crude oil-contaminated soils. Morphological and molecular studies indicated that isolated fungi belonged to genera Aspergillus, Penicillium, Fusarium, Trichoderma, Scedosporium, and Acremonium and bacteria to Pseudomonas, Klebsiella, Bacillus, Enterobacter, Streptomyces, Stenotrophomonas, Kocuria, and Delftia genera. Individual fungal and bacterial isolates were evaluated for their potential to tolerate high concentrations of different molecular weight PAHs, as phenantrene (Phe), pyrene (Pyr), and benzo{[
Sequential-co-culture technique was investigated in this study for the production of bioethanol from relatively cheaper lignocellulosic biomass of Kans grass (Saccharum spontaneum). The consortium of Pichia stipitis and Zymomonas mobilis was used to develop a suitable sequential-co-culture system. The Kans grass biomass was hydrolyzed in such a manner that the two sugar fractions, xylose rich and glucose rich were generated (a separate study). The P. stipitis cells and respective fermentation media (xylose rich) were fed to the fermentation vessel, after the set fermentation time Z. mobilis cells and respective media were fed to the same vessel. Different strategies have been followed and experiments were conducted initially at flask level. The selected strategy was then applied at bioreactor level using both synthetic fermentation media and Kans grass hydrolysate media to compare the kinetic parameters. The sequential addition of cultures with their respective media and imposed process conditions, showed better utilization of total sugars added (>95\%). Microaerobic condition for P. stipitis and strictly anaerobic condition for Z. mobilis fermentation were found significant. The average ethanol yield (Y-p/s) and overall volumetric productivity (r(po)) were found as 0.453 g(p)/g(s) and 1.580 g/l/h respectively for Kans grass hydrolysate media and 0.474 g(p)/g(s) and 2.901 g/l/h respectively for synthetic fermentation media. (C) 2013 Elsevier B.V. All rights reserved.
Pulp and paper industry is one of the high priority sectors that generates large amount of solid (sludge) and liquid (paper mill effluent) wastes. Making use of this huge quantity of paper mill sludge (PMS) in an environment friendly manner is challenging and cost involving. Similarly the present wastewater treatment strategies based on physical and chemical methods encounter certain serious setbacks including secondary pollution generation with expensive mode of abatement processes. The present study aims at a ``waste treats waste{''
A physico-chemical kinetic model for the hydrolysis of pre-treated corn stover is proposed. This model takes into account two reactions in series, the hydrolysis of cellulose to cellobiose and the production of glucose from cellobiose. Experiments have been carried out with an industrial enzymatic cocktail from Trichoderma reesei containing endo and exoglucanases and a very low activity of beta-glucosidase. Kinetic parameters were calculated by fitting the proposed model to experimental data of cellulose and glucose concentrations with time. The kinetic parameters fulfilled all relevant statistical and physical criteria. The kinetic model has been validated with published saccharification data regarding differently pre-treated corn stover and enzymatic cocktail, in this case with a very high beta-glucosidase activity (as it is common in modern industrial cellulase cocktails). In both cases, the kinetic model proposed could be fitted very appropriately to cellulose hydrolysis data.
In this study, fluidized bed drying experiments were conducted for poplar wood particles (Populus deltoides) at temperatures ranging from 90 degrees C to 120 degrees C and air velocities ranging from 2.8 m s(-1) to 3.3 m s(-1). The initial moisture content (MC) and the bed height of the poplar wood particles were 150\% (on an oven-dry basis) and 2 cm, respectively. The results showed that the drying rate increased by increasing the drying temperature and air velocity. The constant drying rate period was only observed at the early stages of the drying process and most of the drying processes were found in the falling rate period. The experimental data of the drying process were put into e11 models. Among these models, Midilli, Kucuk, and Yapar (2002) and Henderson and Pabis (1961) were found to satisfactorily describe the drying characteristics of poplar wood particles. The effective moisture diffusivity of wood particles increased from 7E-6 to 8.46E-6 and 7.65 E-6 to 1.44E-5 m(2) s(-1) as the drying air temperature increased from 90 degrees C to 120 degrees C for 2.8 m s(-1) and 3.3 m s(-1) of velocities, respectively. Also, the activation energies of diffusion were 34.08 kJ mol(-1) and 64.70 kJ mol(-1) for the air velocities of 2.8 m s(-1) and 3.3 m s(-1), respectively.
Background. Many biotechnological and industrial applications can benefit from cold-adapted EglCs through increased efficiency of catalytic processes at low temperature. In our previous study, Citrobacter farmeri A1 which was isolated from a wood-inhabiting termite Reticulitermes labralis could secrete a cold-adapted EglC. However, its EglC was difficult to purify for enzymatic properties detection because of its low activity (0.8 U/ml). The objective of the present study was to clone and express the C. farmeri EglC gene in Escherichia coli to improve production level and determine the enzymatic properties of the recombinant enzyme. Methods. The EglC gene was cloned from C. farmeri A1 by thermal asymmetric interlaced PCR. EglC was transformed into vector pET22b and functionally expressed in E. coli. The recombination protein EglC22b was purified for properties detection. Results. SDS-PAGE revealed that the molecular mass of the recombinant endoglucanase was approximately 42 kDa. The activity of the E. coli pET22b-EglC crude extract was 9.5 U/ml. Additionally, it was active at pH 6.58.0 with an optimum pH of 7.0. The recombinant enzyme had an optimal temperature of 3040 degrees C and exhibited >50\% relative activity even at 5 degrees C, whereas it lost approximately 90\% of its activity after incubation at 60 degrees C for 30 min. Its activity was enhanced by Co2+ and Fe3+, but inhibited by Cd2+, Zn2+, Li+, Triton X-100, DMSO, acetonitrile, Tween 80, SDS, and EDTA. Conclusion. These biochemical properties indicate that the recombinant enzyme is a cold-adapted endoglucanase that can be used for various industrial applications.
The production of xylooligosaccharides (XOS) from Jiuzao was studied using a two-stage process based on autohydrolysis pretreatment followed by enzymatic hydrolysis. Jiuzao was autohydrolyzed under conditions where temperature, time, particle size, and solid-liquid ratio were varied experimentally. Optimal XOS production was obtained from Jiuzao with a >20 mesh particle size treated at 181.5 degrees C for 20 min with a 1:13.6 solid-liquid ratio. Subsequently, optimal enzymatic hydrolysis conditions for xylanase XynAR were identified as 60 degrees C, pH 5, and xylanase XynAR loading of 15 U/mL. Using these conditions, a yield of 34.2\% XOS was obtained from Jiuzao within 2 h. The process developed in the present study could enable effective and ecofriendly industrial production of XOS from Jiuzao.
The present experimental study reports the performance of tea waste (TW) derived adsorbent for the adsorption of sodium diclofenac (SD) from aqueous solution (SD concentration=10-50mg/L). The waste-derived activated carbon was prepared by chemical activation process of raw waste using H2SO4, KOH, ZnCl2, and K2CO3 as activating agents (TW: activating agent=1:1 by weight). Subsequently, the oven-dried material was carbonized at 600-degrees C temperature for 2h. The synthesized adsorbents were porous and their Brunauer-Emmett-Teller (BET) surface area was ranged 115-865m(2)/g. Among all synthesized adsorbents, the adsorbent activated by ZnCl2 exhibited the highest adsorption capacity (=62mg/g), though it was much lower compared to 91mg/g obtained with commercial activated carbon (CAC) (SD concentration=30mg/L, adsorbent dose=300mg/L and initial wastewater pH=6.47). SD equilibrium data could be described by Langmuir isotherm adequately, while pseudo-second-order rate model showed better fit to the time based adsorption data. Low activation energy of the adsorption process suggests the reaction to be temperature independent. Thermodynamic parameters showed the spontaneous and endothermic nature of adsorption process conducted in the presence of waste derived adsorbent.
Fresh water streams contaminated with synthetic dye-containing effluents pose a threat to aquatic and human life either by preventing aquatic photosynthesis or by entering into the food chain. Adsorptive removal of such dyes with potent biosorbents is an important technique to reduce bioaccumulation and biomagnifications of the dyes in human life. We report use of betel nut (BN) husk and banana peel (BP), two most abundant ligno-cellulosic wastes, as efficient adsorbents for the removal of the basic dye methylene blue (MB). The adsorption by BN and BP was consistently high over wide ranges of pH and temperature, suggesting their dye removal potential in diverse conditions. Physico-chemical studies, e.g. scanning electron microscopy and Fourier transform-infrared spectroscopy studies, revealed changes in surface topology and functional moieties of BN and BP post adsorption, implying dye interaction with the biomass surface. The dye adsorption in both cases followed pseudo-second-order kinetics. While adsorption of MB by BN was better fitted with the Temkin isotherm model, adsorption with BP followed both Langmuir and Freundlich isotherm models. Our studies concluded that both adsorbents efficiently remove MB from its aqueous solution with BP proved to be marginally superior to BN.
The fungus Aspergillus japonicus ATCC 20236 was immobilized in vegetal fiber and used in repeated batch fermentations of sucrose (200 g/l) for the production of beta-fructofuranosidases (FFase). The assays were performed during eight consecutive cycles that were completed in a total period of 216 h. After each 24-h cycle of fermentation (except for the first cycle, which lasted 48 h), the fermented broth was replaced by fresh medium, and the FFase activity was determined in the replaced medium. The average value of FFase activity was a constant 40.6 U/ml at the end of the initial seven cycles, but had decreased by 22\% at the end of the eighth cycle. Concurrent with these high and constant FFase values, the hydrolyzing activity of this enzyme increased during the cycles, while the transfructosylating activity decreased. As a consequence, the maximum production of fructooligosaccharides of 134.60 g/l observed in the initial 30 h of fermentation (first cycle) had gradually decreased by the end of the subsequent cycles, reaching approximately 23\% of this value during cycles 4-8. Based on these results, we conclude that the present immobilization system has a great potential for application in a semi-continuous process for the production of FFase, but further studies are necessary to maintain the FFase transfructosylation activity at high levels during the overall process.
In this paper a self-developed polycrystalline diamond coating was done on tungsten carbide (WC) tool insets by using simple thermal chemical vapor deposition technique. The growth of these diamond films has been carried out at similar to 900 degrees C temperature. The as-grown polycrystalline diamond films on the surface of tungsten carbide tool inserts have been characterized using Raman spectrometer and scanning electron microscope (SEM). The morphological studies reveal that the as-grown diamond films are of high crystalline quality. The as-grown diamond films possess compressive stress. The micro-hardness indentation test of the as-grown diamond films on WC tool inserts and bare have also been done and it has been found that the Vicker's hardness of the as-grown diamond WC tool inserts is found to be 1423.32 HV which is 29\% better than the un-coated tools.
This study aimed to investigate the production of biobased volatile fatty acids (VFAs) from pretreated olive mill solid waste (OMSW). Three hydrothermal pretreatment (HP) conditions (D1: 125 degrees C, 53 min; D2: 161 degrees C, 62 min; D3: 191 degrees C, 83 min) were selected. The pretreated olive mill solid fraction (OMSF), pretreated olive mill liquid fraction (OMLF), and pretreated OMSW were evaluated as potential substrates for acidification in the anaerobic digestion (AD) in liquid (L-AD), semi-solid (Ss-AD), and solid (S-AD) phases. The best acidification efficiency (AE) observed in this study was 65\%, for L-AD and HP condition D2 (161 degrees C, 62 min). However, the HP condition D2 applied to the Ss-AD provided a VFA concentration of 18218 mg L-1, about 6-fold higher than that observed in the L-AD system. Polyphenols changed the profile of VFAs, increasing the production of longer chain VFAs in the L-AD and S-AD systems. Also, the influence of the typology of the AD system and HP severity on the microbial community was evaluated. Proteobacteria and Firmicutes were the most representative phyla in acidogenic fermentation of OMSW substrates and the genera Enterobacter, Pseudomonas, Achromobacter, Clostridium, Ochrobactrum, and Peptoclostridium played an important role in the pretreated OMSW fermentation and, consequently, in the VFAs production profile.
Herein, we studied two strains of halophilic fungi (Aspergillus fiavus and Aspergillus penicillioides) as potential potent sources of hydrolases under solid-state fermentation conditions. We found that the co-culture of these two fungal species was associated with maximal CMCase, FPase, xylanase, and p-xylosidase activity under optimized fermentation conditions. These enzymes functioned optimally at pH values from 9.0 to 10.0, at temperatures from 50 degrees C to 60 degrees C, and in the presence of 15-20\% NaCl. These enzymes were also stable in metal salt solutions and the presence of ionic liquids. Reducing sugar yields following the cellulase-hemicellulase co-treatment of untreated, alkaline-pretreated, and ionic liquid-pretreated bamboo were higher than those associated with separate cellulase and hemicellulase treatments, thus confirming the synergistic activity of cellulase-hemicellulase co-treatment in the context of bamboo saccharification. These results indicate that these two fungi are promising hydrolase producers that can facilitate the bioconversion of bamboo biomass.
The effectiveness of micro-aeration on lactate (LA) production by metabolically engineeredEscherichia coliwas evaluated in 1 L bioreactors containing mineral media and glucose (70 g/L). Volumetric oxygen transfer coefficients (k(L)a) between 12.6 and 28.7 h(-1)increased the specific growth rate (mu) and volumetric productivity (Q(LA)) by 300 and 400\%, respectively, without a significant decrease in lactate yield (Y-LA), when compared with non-aerated fermentations. A k(L)a of 12.6 h(-1)was successfully used as a criterion to scale-up the production oflandd-lactate from 1 to 11 and 130 L. Approximately constant Q(LA)and Y(LA)values were obtained throughout the fermentation scale-up process. Furthermore, ad-lactogenic fermentation was carried out in 1 L bioreactors using avocado seed hydrolysate as a culture medium under the same k(L)a value, displaying high Q(LA)and Y-LA.
This paper investigated the impact of the amounts of lignin and hemicelluloses on cellulose nanofibers (CNFs). Birch and spruce wood were used to prepare holocellulose and cellulose samples by classical methods. To better assess the effect of the chemical composition on the CNF performance and simplify the process for CNF preparation, no surface derivatization method was applied for CNF preparation. Increased amounts of hemicelluloses, especially mannans, improved the defibration process, the stability of the CNFs and the mechanical properties, whereas the residual lignin content had no significant effect on these factors. On the other hand, high lignin content turned spruce nanopapers yellowish and, together with hemicelluloses, reduced the strain-at-break values. Finally, when no surface derivatization was applied to holocellulose and cellulose samples before defibration, the controlled preservation of residual lignin and hemicelluloses on the CNFs indicate to be crucial for the process. This simplified method of CNF preparation presents great potential for forest-based industries as a way to use forestry waste (e.g., branches, stumps and sawdust) to produce CNFs and, consequently, diversify the product range and reach new markets.
Dilute sulfuric acid pretreatment was used to improve the biomethane production from wheat plant (WP) via mesophilic anaerobic digestion. The pretreatments were performed at 121 degrees C for different time durations of 10, 30, 60, and 120 min. The maximum methane yield of 302.4 mL/g volatile solids (VS) was obtained after the pretreatment for 120 min, which was 15.5\% higher than that of the untreated WP. The highest amounts of lignin removal (15.2\%) and xylan degradation (91.5\%) were also achieved after this pretreatment. The pretreatment for 60 min enhanced the methane yield by 8.9\%, while the pretreatments for 10 and 30 min had no positive effects on the methane yield. All of the pretreatments significantly removed the hemicelluloses. Moreover, the qualitative analysis of the untreated and pretreated WP structure showed significant reduction in the crystallinity index accompanied by the destruction of surface layers of WP structure after pretreatment.
Eggshell waste is among of the most abundant agro-waste material discharged from food processing industries. Despite the exceptional properties and several applications, eggshell is castoff in huge quantity without any further use. This review paper focuses on appraising the potential uses of eggshell waste as a feedstock for production of sustainable construction materials. The emphasis is on the need to exploit extensively eggshell waste as a partial cement replacement material in clay and cement-based construction materials. The physical-chemical properties of eggshell powder which describe its unique characteristics are discussed. The exploitation of eggshell waste in various construction materials have resulted into an overall improvement in the physical-mechanical properties. The results from reviewed work show that, the incorporation of 5-30 \% of eggshell powder has developed green sustainable construction materials with properties that are within the range for the established engineering standards. In the current paper, it was indicated that the valorisation of eggshell waste has a potential to replace cement material for production of cheap and sustainable construction materials with improved engineering properties. Based on circular economy, valorisation is regarded to be a cost-effective solution to provide eco-friendly industrial raw materials while ensuring a waste free environment in the future.
The present study proposes valorization of amla (Phyllanthus emblica) pomace for the isolation of cellulose nanocrystals (CNCs) to provide a sustainable and low-cost precursor material for the production of nano-based biomaterials. The raw fibers were subjected to bleaching and alkali treatments to obtain cellulose, followed by acid hydrolysis for the isolation of CNC. The resultant nanocrystals were characterized for structural changes using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and transmission electron microscope (TEM). FTIR results showed progressive removal of noncellulosic components such as hemicellulose and lignin. This rendered CNCs with a 45\% yield, negative zeta potential value of - 32.33 mV showing greater colloidal stability, and a higher crystallinity index of 45\% as determined by XRD. Thermogravimetric analysis revealed that isolated CNCs have higher thermal stability (> 200 degrees C). TEM images showed that the CNCs exhibit rod-like structures in nano-dimensions with a higher aspect ratio of 10.83. This study will not only aid in the sustainable conversion of food industry waste into a value-added product but also promote the circular economy. This may further help to reduce global emissions and address the key challenges of climatic change.
In the present work, we have successfully demonstrated the deposition of environment friendly diamond coating on a steel substrate using thermal CVD process for piston ring application. The FESEM, Raman spectra (at 1332.4 cm(-1)) and HRXRD. The peak witnessed at 2 circle minus = 43.9(0) and 75.3 degrees indexed to (111) and (220) cubic phased diamond respectively, while the peak witnessed at 2 circle minus = 44.6(0) and 82.6 degrees indexed to (103) and (1012) hexagonal phased diamond, confirms the presence of diamond coating with excellent tribological performance (COF) and good mechanical properties (residual stress). The aim of present work is to optimize the tribological properties and wear mechanism of thermal CVD diamond coating using Taguchi L9 orthogonal array (OA). The significant process parameters for COF according to their contribution in percentage of sliding velocity (75.49\%) was highest followed by temperature (12.93\%) and load (8.09\%). The highest percentage contribution for percentage (\%) change in residual stress was of temperature (57.01\%) followed by sliding velocity (33.04\%) and load (5.14\%).
Residues from the processing of cassava roots (Manihot esculenta Crantz), or cassava peels, are evaluated as chemically modified adsorbents with H2O2, H2SO4, and NaOH, in the removal of metal ions Cd(II), Pb(II), and Cr(III) from contaminated water. Modified adsorbents were chemically characterized for their chemical composition and pHPZC (point of zero charge), while adsorption tests determined the best conditions of pH, adsorbent mass, and contact time between adsorbent and adsorbate in the process of removal of themetal ions. Isotherms obtained from the preliminary results were linearized by Langmuir's and Freudlich's models. The thermodynamic parameters, such as Delta H, Delta G, and Delta S, were also evaluated. The modifying solutions proposed were effective in the modification of adsorbents and resulted in high capacity sorption materials. Equilibrium time between adsorbent and adsorbate for the solutions contaminated with metals is about 40 minutes. The Langmuir model adjusted to most results, indicating monolayers adsorption of Cd(II), Pb(II), and Cr(III). The values obtained for Langmuir Q(m) show a higher adsorption capacity caused by chemical modifications, with values such as 19.54mg Cd(II) per g of M. NaOH, 42.46mg of Pb(II) per g of M. NaOH, and 43.97mg of Cr(III) per g of M H2O2. Results showed that modified cassava peels are excellent adsorbent, renewable, high availability, and low-cost materials and a feasible alternative in the removal of metals in industries.
Torrefaction is a low-temperature thermochemical treatment technology to enhance solid biomass fuel properties for energy applications. The available literature on torrefaction thermal pre-treatment presented the extent of improvement in fuel quality at various operating conditions however with non-practical industrial approach using energy intensive heating methods i.e. external heaters and with simulated gas composition. This work investigates the utilisation of real-time low-grade combustion waste heat and flue gases to produce torrefied biomass pellets at 225 degrees C and 250 degrees C in a fixed-bed reactor. The fuel quality, hydrophobicity, chemical functionality inorganics contents, and combustion kinetics of the flue gas torrefied (FGT) biomass fuel were thoroughly analysed and compared with the torrefied pellets produced under partially oxidative conditions (at 250 degrees C) using electrical heaters. The results suggest that flue gas torrefaction improves the heating value of the raw biomass by up to 11 \%. The hydrophobicity (water resistivity) of the FGT biomass was also improved and comparable with the fuels derived from electrically heated partial oxidative torrefaction (POT). The presence of carbon dioxide in the flue gases did not adversely affect the quality of the FGT biomass fuel. In fact, FGT biomass attained relatively higher i.e. 92.1 \% energy yield compared to 87.9 \% of POT biomass. In addition, low concentrations of alkali and alkaline earth metals (AAEM) were observed in FGT biomass compared to POT biomass fuel. The outcome of this work suggests that torrefaction using combustion waste heat and flue gases is a viable and cost-effective thermal treatment method to upgrade biomass fuel quality.
Jerusalem artichoke (Helianthus tuberosus L.) is emerging as one of the energy plants considered for biofuel production. Alkali and alkali-involved pretreatment methods have been widely used for the bioconversion of cellulosic materials due to their high sugar yield and low inhibitor release. However, the recovery and treatment of wastewater (black liquor) have been poorly studied. Here, we present a novel two-stage pretreatment process design for recycling black liquor. Jerusalem artichoke stalk (JAS) was first treated with 2\% (w/v) NaOH, after which lignin was recovered by H2SO4 at pH 2.0 from the black liquor. The recycled solutions were subsequently used to treat the NaOH-pretreated JAS for the second time to dissolve hemicellulose. CO-pretreated JAS, hydrolysates, and acid-insoluble lignin were obtained after the above-mentioned two-stage pretreatment. A reducing sugar yield of 809.98 mg/g Co-pretreated JAS was achieved after 48 h at 5\% substrate concentration using a cellulase dosage of 25 FPU/g substrate. In addition, hydrolysates containing xylose and acid-insoluble lignin were obtained as byproducts. The pretreatment strategy described here using alkali and acid combined with wastewater recycling provides an alternative approach for cellulosic biorefinery.
In lignocellulose biorefineries, the profitability of the process is dependent on efficient feedstock use. To fully valorize all carbohydrates from corn cobs, a newly integrated strategy was developed as a two-step treatment with formic acid for simultaneous production of furfural and ethanol. Corn cobs were first treated with concentrated formic acid at 80 degrees C for 3 h, and an easily digestible residue with high purity cellulose was fractionated. Following post-treatment, enzymatic hydrolysis, and fermentation, 67.9 g/L ethanol was obtained at 160 g/L initial glucan loading with a high total yield of 75.6\%. The fractionated spent liquor was then treated at a high temperature after recovering a large amount of formic acid and lignin by simple rotary evaporation and precipitation. The results showed that the remaining hemicellulose sugar could be converted into furfural using residual formic acid in syrup (31.3 g/L) as a self catalyst. After optimization of the process, 49.3\% furfural yield and 10.8 g/L furfural were achieved at 160 degrees C for 60 min with the aid of AlCl3. The two-step approach based on formic acid pretreatment exhibited excellent performance in the efficient conversion of corn cobs into chemicals and energy, which shows enormous potential for biomass refining. (C)\& nbsp;2022 Published by Elsevier Ltd.
A breakthrough biosorbent namely multi-metal binding biosorbent (MMBB) made from a combination of tea wastes, maple leaves and mandarin peels, was prepared to evaluate their biosorptive potential for removal of Cd(II), Cu(II), Pb(II) and Zn(II) from multi-metal aqueous solutions. FTIR and SEM were conducted, before and after biosorption, to explore the intensity and position of the available functional groups and changes in adsorbent surface morphology. Carboxylic, hydroxyl and amine groups were found to be the principal functional groups for the sorption of metals. MMBB exhibited best performance at pH 5.5 with maximum sorption capacities of 31.73, 41.06, 76.25 and 26.63 mg/g for Cd(II), Cu(II), Pb(II) and Zn(II), respectively. Pseudo-first and pseudo-second-order models represented the kinetic experimental data in different initial metal concentrations very well. Among two-parameter adsorption isotherm models, the Langmuir equation gave a better fit of the equilibrium data. For Cu(II) and Zn(II), the Khan isotherm describes better biosorption conditions while for Cd(II) and Pb(II), the Sips model was found to provide the best correlation of the biosorption equilibrium data. The calculated thermodynamic parameters indicated feasible, spontaneous and exothermic biosorption process. Overall, this novel MMBB can effectively be utilized as an adsorbent to remove heavy metal ions from aqueous solutions. (C) 2015 Elsevier B.V. All rights reserved.
Lignocellulosic biomass samples (wheat chaff) were pretreated by ultrasound (US) (40 kHz/0.5 W cm(-2)/10 min and 400 kHz/0.5 W cm(-2)/10 min applied sequentially) prior to digestion by enzyme extracts obtained from fermentation of the biomass with white rot fungi (Phanerochaete chrysosporium or Trametes sp.). The accessibility of the cellulosic components in wheat chaff was increased, as demonstrated by the increased concentration of sugars produced by exposure to the ultrasound treatment prior to enzyme addition. Pretreatment with ultrasound increased the concentration of lignin degradation products (guaiacol and syringol) obtained from wheat chaff after enzyme addition. In vitro digestibility of wheat chaff was also enhanced by the ultrasonics pretreatment in combination with treatment with enzyme extracts. Degradation was enhanced with the use of a mixture of the enzyme extracts compared to that for a single enzyme extract. (C) 2014 Published by Elsevier B.V.
Sorghum bicolor (S.B.) is used in this work for preparing chemically modified adsorbent for toxic metal ions, i.e., cadmium(II) and copper(II). Thiourea is selected for chemical modification of this plant waste by microwave solid fusion methodology, so that its chelating ability for metal ions can be enhanced in both acidic and basic conditions, in a cheaper and quicker way. Characterization was carried out by different physiochemical means using FT-IR, SEM, etc. An increase in pH(pzc) value was observed in TSB, which is confirmed by FT-IR analysis. The effect of biosorption process parameters was also studied and found that maximum removal of these toxic ions occurred in slightly acidic pH (5-6) conditions, following pseudo-second-order kinetic model. Boyd plots indicated that film dispersion mode was the rate-determining step. Langmuir model indicated that the maximum metal ion removal capacity of TSB was 17.241 mg/g and 15.151 mg/g for cadmium(II) and copper(II) ions. So, TSB can be used on a larger scale for toxic metal ion removal by Sorghum bicolor waste in a cleaner way.
Cellulose-based advanced materials, such as cellulose nanocrystals (CNC), have high potential application for drug delivery system. In this study, the CNC were produced from bamboo shoots using acid hydrolysis process. The delignification of bamboo shoots was conducted using alkali and hydrogen peroxide pretreatment processes. The operating condition of the production of CNC from bamboo shoots was optimized using Response Surface Methodology (RSM) based on the yield and crystals recovery as the responses. The optimum CNC yield of 50.67 +/- 0.74\% with a crystals recovery of 77.99 +/- 1.14\% was obtained at the sulfuric acid concentration of 54.73 wt\% and a temperature of 39 degrees C from the optimization based on the yield. This optimization has been validated to confirm the accuracy.
Waste paper has considerable potential as a raw material for lactic acid (LA) production due to high cellulose content, abundance and low cost. In this study, four kinds of waste papers were used for LA production through simultaneous saccharification and fermentation (SSF) by Streptococcus thermophilus. The SSF of office paper achieved the highest LA concentration (39.71 g/L), while the highest LA yield was observed for magazine (99.56\%), followed by office paper (82.85\%). High LA concentration is unfavorable to total LA conversion because of product inhibition. However, the addition of Gleditsia saponin (GS) could obtain both high yield and high concentration of LA at a low enzyme loading, indicating that product inhibition could be moderated. A lactic acid yield of 86.30\% was obtained from office paper at an enzyme loading of 9 FPU/g-cellulose with GS, which was higher than that of without GS at a higher loading of 18 FPU/g-cellulose.
In the present study, a comparison of two types of microwave pretreatment such as microwave assisted alkali and microwave assisted acid were studied using cassava pulp as the substrate. The effect of pretreatment agent concentration, microwave power and pretreatment time on enzymatic saccharification was studied using a response surface method according to Central Composite design. Under optimized conditions, microwave assisted alkali pretreatment of cassava pulp with 2.27\% NaOH at 125 W for 18 min followed by enzymatic hydrolysis gave reducing sugar yield of 0.472 g g(-1) dry biomass, while microwave assisted acid treatment with 1.95\% H2SO4 at 135 W for 25 min showed reducing sugar yield of 0.306 g g(-1) dry biomass. The yield from microwave assisted alkali was higher and was 2.7 times higher than that obtained with raw cassava pulp. Microwave assisted liquefaction of pretreated cassava pulp at 100 W for 30 min using amylase lowered the process time. (C) 2017 American Institute of Chemical Engineers
The ground pine wood chips (GPWC) were examined through chemical treatment methods employing alkaline hydrogen peroxide treatment (AHP, consisted of 50 g L-1 potassium hydroxide, and 50 g hydrogen peroxide with added water at 78 degrees C for 24 h), and ethyl-hydro-oxides treatment (EHOs, consisted of 60\% ethanol (of total solution), 50 g L-1 potassium hydroxide, and 50 g L-1 hydrogen peroxide with added water at 78 degrees C for 24 h). The effects of chemical treatments on GPWC were examined through combination of chemical composition followed by enzymatic hydrolysis (using Accellerase((R)) 1500). The application of EHOs treatment removes the foaming issue that currently occurs due to AHP treatment at the elevated temperature. A removal of the foaming phenomenon increased the enzymatic glucan conversion (>70\%) which is important in increasing the efficiency of biorefinery. The interaction of different variables in EHOs solvent formulations including ethanol concentration (0-60\%), potassium hydroxide concentration (0-50 g L-1), hydrogen peroxide concentration (0-50 g L-1), and processing temperature (38 degrees-78 degrees C) were analyzed through four variables response surface methodology using glucan conversion and total polysaccharide conversion as responses. The glucan conversion and total polysaccharide conversion were analyzed to determine the specific and overall effects of Accellerase((R)) 1500 on the amorphous polysaccharide contents of GPWC resulted through EHOs treatment formulations, respectively. The implications of all these findings are discussed with the available literature. (C) 2016 Elsevier Ltd. All rights reserved.
The control of microbial infection transmission often relies on the utilization of synthetic and metal-based antimicrobial agents. However, their non-biodegradability and inadequate disposal practices lead to significant environmental contamination. To address this concern, the quest for natural alternatives has gained paramount importance. Lignin, a widely available renewable aromatic compound, emerges as a promising candidate owing to its inherent phenolic moiety, which lends itself well to acting as a natural antimicrobial agent either independently or in combination with other agents. This article provides a comprehensive account of the structure and primary classes of lignin. Additionally, it elucidates the antimicrobial mechanism of lignin, the factors influencing its efficacy, and the methods employed for its detection. Moreover, it describes the progress made in developing the antimicrobial capacity of lignin in different areas. In conclusion, this paper not only outlines the current state of research on the antimicrobial function of lignin, but also identifies challenges and future possibilities for enhancing its antimicrobial properties. This work holds great significance in the ongoing endeavor to contribute to high-impact research on natural alternatives for controlling infections and fostering environmentally conscious practices.
This study was conducted to recover silica (desilication) as a valuable metalloid from waste foundry sand (WFS) by a leaching process and to find application for desilicated foundry sand (DFS). The leaching time applied was 5 h; 3 M of potassium hydroxide (KOH) was used as a leaching reagent. The agitation speed of 200 rpm and the liquid/solid ratio of 25 were found to be the best conditions for optimum leaching results. A geopolymer from DFS was developed by using NaOH as an alkaline activator. The results obtained showed that the optimum conditions for the synthesis of a geopolymer were 15 M NaOH, 150 mu m DFS particle size, and a curing temperature of 80 ? for 72 h. The geopolymer strength development was due to the formation of Phillipsite and Kalsilite as new hydration products. At the optimum alkaline solution concentration, the highest unconfined compressive strength (UCS) of 4.8 MPa was achieved. The developed geopolymer met the minimum strength requirements for load bearing material. This study provides an innovative and novel solution for the beneficiation of spent foundry sand and the recovery of a valuable metalloid, resulting to zero waste generation.
The study of biomass is extremely important, aiming to discover the potential of alternative source that are capable of promoting the development of new technologies. The thermal behavior and chemical characteristics of theCapsicumwaste from the use for the manufacture of sauces and condiments were investigated using thermogravimetric analysis, higher heating values, ignition (T-i) and burnout temperatures (T-b) and kinetic study using isoconversional models. Torrefaction and pyrolysis conditions were applied. Characterization based on ultimate and proximate analysis, gravimetric and gravimetric yield factor were also realized. Thermal analysis showed a biomass conversion between 150 degrees C and 500 degrees C. Proximate analysis identified an average volatile content of 46.5\%, and carbon and fixed carbon were 22.3 and 31.1\%, respectively. Gravimetric yield varied between 28 and 58\%. Considering the intersection model, ignition and burnout temperature varied between 342-354 degrees C and 470-503 degrees C, respectively. The deviation model found an ignition temperature between 210 and 249 degrees C. Biomass proved to be a possible source of biofuel with a significant economic potential.
This study analyzed the techno-economic feasibility of a biomass conversion process enabled by high-solid loading deep eutectic solvent (DES) pretreatment for the co-production of 2,3-butanediol (BDO), furfural, and technical lignin. Aspen plus was used for process simulation; economic analysis models were developed to evaluate commercial potential; sensitivity analysis was carried out to evaluate the effects of key parameters on the production cost of 2,3-BDO; and Monte-Carlo simulation was used for uncertainty analysis. Two cases of high-solid loading pretreatment (20\% versus 27\%) for DES pretreatment were compared. The process simulation results indicate that 78-79\% of cellulose, 63-70\% of xylan, and 40-44\% of lignin in raw switchgrass are converted into 2,3-BDO, furfural, and technical lignin, respectively. The minimum 2,3-BDO selling price (MBSP) of these two cases is estimated to be 1703-1736 \$ ton(-1), which is about half of the current 2,3-BDO market price. Sensitivity analyses show that the prices and recycle ratios of acetone and methyl isobutyl ketone (MIBK) have larger impacts on the MBSP, which indicates that further technical improvement should focus on reducing their consumption. The uncertainty analysis indicates that 20 and 27\% solid loading systems have similar confident intervals, with 90\% confidence interval of MBSP ranging from 1450-1990 \$ ton(-1). (c) 2020 Society of Chemical Industry and John Wiley \& Sons, Ltd
The increasing global demand for sustainable materials has drawn academic and industrial attention towards lignocellulosic resources. One emerging non-wood source is Australian spinifex arid grass. Exploration of this unique resource is particularly important due to its abundance, extreme drought-tolerance, renewability, and low cost. In this study, mild-alkali treated spinifex grass was subjected to twin-screw extrusion (TSE), high-energy ball milling (HEBM), and high-pressure homogenization (HPH) in order to fibrillate the material into cellulose microfibers (MFC) and nanofibers (CNF). Transmission electron microscopy images confirmed that at least a substantive proportion of CNF is produced by all processes. The overall network density in the confocal laser scanning microscopy images correlated with the normalized light transmittance of the handsheets. The normalized transmittance data suggested that HPH and HEBM produce a high proportion of CNF, as the handsheets made from the material obtained by those methods exhibited translucency. The opacity and relatively low mechanical properties of the handsheets made from the TSE processed fibers suggested a high proportion of MFC present in the treated pulp. However, TSE was found to be the lowest-energy consuming process, making it an attractive fibrillation process. {[
Nanocrystalline cellulose (NCC) has gained much popularity over the last decade as a preferred nanomaterial in varied applications, despite its laborious industrial production and higher cost. Its production methods have undergone a great deal of metamorphosis lately. The main emphasis has been on the environment-friendly and green processes, in addition to the sustainable and renewable feedstock. Globally, the researchers have explored biomass and waste cellulosic materials as renewable sources for NCC extraction. Newer and/or improved process alternatives, e.g., ultrasonication, enzymatic hydrolysis and mechanical treatments have been applied successfully for producing high-quality material. Detailed investigations on optimizing the overall yield from cheaper feedstock have yielded obvious benefits. This is still work in progress. The present review majorly focuses on the advances made in the NCC preparation field from biomass and waste cellulosic materials in last three years (2016 - till date). Collaborative efforts between chemical engineers and research scientists are crucial for the success of this really amazing nanomaterial.
Cellulose acetates (CA) with different degrees of acetylation were synthesized from cellulose extracted from corn stover. Membranes were prepared for the ultrafiltration process with pure polymers and blend form of CA utilizing a dioxane/acetone system. The membranes were characterized according to their transport properties. The blend form materials presented the best results for application in ultrafiltration experiments. M-TAC/DAC (corn stover triacetate and diacetate) and M-TAC/DAC-Rho (corn stover triacetate and Rhodia diacetate) presented rejection to egg albumin protein of 87.39\% and 80.50\%, respectively. Thus, MWCO of 45 kDa was determined for these materials.
In this work, Eucalyptus grandis sawdust was subjected to steam explosion as the first step in cellulosic ethanol production within a biorefinery approach. The effect of the moisture content in the eucalypt sawdust (8 and 50\%) and pretreatment process variables, such as temperature and residence time, were evaluated along with the influence of the water washing of steam-exploded solids on enzymatic hydrolysis and C6 fermentation yields. All other process streams were characterized to evaluate the recovery yield of valuable co-products. A recovery of nearly 100\% glucans in the solid fraction and 60\% xylans in the liquid fraction, mainly as partially acetylated oligomers, was obtained. The best enzymatic hydrolysis efficiencies (66-67\%) were achieved after pretreatment at 205 \& DEG;C for 10 min. The washing of pretreated sawdust with water improved the hydrolysis efficiencies and ethanol production yields by 10\% compared to the unwashed pretreated solids under the same experimental condition. The highest ethanol yields were achieved after pretreatment of the sawdust with an 8\% moisture content at 205 \& DEG;C for 10 min, enzymatic hydrolysis at 13 wt\% total solids with 25 FPU/g glucans, and fermentation with S. cerevisiae PE-2. In this case, 227 L ethanol and 40 kg total xylose (including xylo-oligomers) were obtained per ton of dry eucalypt sawdust.
Xylooligosaccharides (XOS) are prebiotic nutraceuticals that can be sourced from lignocellulosic biomass, such as agro-residues. This study reports for the first time an optimization study of XOS production from agro-residues by direct fermentation using two Trichoderma species. A total of 13 residues were evaluated as potential substrates for single-step production. The best results were found for Trichoderma reesei using brewers' spent grain (BSG) as substrate. Under optimal conditions (3 days, pH 7.0, 30 degrees C and 20 g/L of BSG), a production yield of 38.3 +/- 1.8 mg/g (xylose equivalents/g of BSG) was achieved. The obtained oligosaccharides were identified as arabino-xylooligosacharides (AXOS) with degree of polymerization from 2 to 5. One-step fermentation proved to be a promising strategy for AXOS production from BSG, presenting a performance comparable with the use of commercial enzymes. This study provides new insights towards the bioprocess integration, enabling further developments of low-cost bioprocesses for the production of these valuable compounds.
Sunflower stalks, a largely available and cheap agricultural residue lacking of economic alternatives, were subjected to steam explosion pretreatment, the objective being to optimize pre-treatment temperature in the range 180-230 degrees C. Enzymatic hydrolysis performed on the pre-treated solids by a cellulolytic complex (Celluclast 1.5 L) and analysis of filtrates were used to select the best pre-treatment temperature. Temperature selection was based on the susceptibility to enzymatic hydrolysis of the cellulose residue and both the cellulose recovery in the solid and the hemicellulose-derived sugars recoveries in the filtrate. After 96 h of enzymatic action, a maximum hydrolysis yield of 72\% was attained in the water-insoluble fiber obtained after pre-treatment at 220 degrees C, corresponding to a glucose concentration of 43.7 g/L in hydrolysis media. Taking into account both cellulose recovery and hydrolysis yield, the maximum value of glucose yield referred to unpretreated raw material was also found when using steam pre-treated sunflower stalks at 220 degrees C, obtaining 16.7 g of glucose from 100 g of raw material. With regard to the filtrate analysis, most of the hemicellulosic-derived sugars released during the steam pre-treatment were in oligomeric form, the highest recovery being obtained at 210 degrees C pre-treatment temperature. Moreover, the utilisation of hemicellulosic-derived sugars as a fermentation substrate would improve the overall bioconversion of sunflower stalks into fuel ethanol. (C) 2007 Elsevier Inc. All rights reserved.
Biobased products are a growing trend in industrial crops, but the natural variation among the plant sources demands the development of efficient pretreatments for standardizing the raw material. This work aims to evaluate the characteristics of pressed oil palm mesocarp fiber after alkaline and multi-step pretreatment methods. Multi-step pretreatment procedure involved acetosolv extraction with a mixture of 93 \% (w/w) of acetic acid and 0.3 \% (v/v) of hydrochloride acid (a chlorine-free), followed by alkaline bleaching. Acetosolv extraction was also used aiming to allow a more effective delignification during the bleaching stage, and the possibility to recover the solvent that was used in the next extractions; this fact could not be obtained in alkaline extraction alone. The fibers were evaluated concerning the chemical composition, X-ray diffraction, thermo-gravimetric analysis, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The combined multi-step resulted in higher alpha-cellulose content (66 \%), crystallinity index (65.20 \%), and lower mass loss up to the onset degradation step.
This study provides a novel value-added utilization of the agroindustrial waste of royal palm tree leaf sheath to produce cellulose acetate. One of the motivations of this work was the fact that Brazil is one of the largest heart of palm producers in the world. However, as a result of extraction and processing, tons of waste are generated and discharged to the environment. Such waste is rich in lignocellulosic material, which could be reused to obtain derivatives of interest and commercial value. The synthesis of cellulose acetate was performed through a homogeneous acetylation reaction. Three different conditions were tested for delignification of the raw material, which resulted in a reduction in lignin content from 17.75 to 7.72\%. The highest yield of cellulose acetate reached 99.5\%, with degree of substitutions ranging between 2.08 and 2.82, which indicates satisfactory conversion. The Fourier transform infrared spectrum showed that practically all hydroxyl groups were replaced by acetate groups; this was also confirmed by nuclear magnetic resonance analysis. X-ray diffraction analysis showed that the cellulose acetate crystallinity index was 8.9\%. This demonstrates the viable potential of cellulose acetate production with low cost and use of highly available agroindustrial waste. POLYM. ENG. SCI., 59:891-898, 2019. (c) 2018 Society of Plastics Engineers
A low-cost, highly efficient and eco-friendly cellulose-based adsorbent (CMGT) was synthesized and used to uptake Pb(II) and malachite green (MG) from aqueous solutions. The CMGT was characterized by FTIR, SEM, TGA and XRD. Different experimental parameters were evaluated in batch adsorption experiments to determine the optimal adsorption conditions. The optimal pHs for Pb(II) and MG were 5.5 and 7.0, respectively; the optimal contact times for Pb(II) and MG were 60 and 180 min, respectively. Among the Langmuir, Freundlich and Temkin isotherm models, the Langmuir model fitted the adsorption data best for both Pb(II) and MG adsorption. In theory, the maximum adsorption capacities of Pb(II) and MG were 584.80 and 131.93 mg g(-1), respectively. The pseudo-second-order model fitted the experimental data very well, and the thermodynamics were also used to discuss the mechanism in depth. Additionally, desorption tests showed that CMGT could be effectively regenerated by 0.2 mol L-1 HCl solution and could be reused for at least six cycles successively with a stable sorption ability in the dynamic adsorption process.
Biohythane production through one-stage anaerobic digestion of sulfate-rich hydrolyzed tofu processing residue has been hampered by high H2S production. Herein, two-stage anaerobic digestion was investigated with the addition of molybdate (MoO42-; 0.24-3.63 g/L) and ferric chloride (FeCl3; 0.025-5.4 g/L) to the dark fermentation stage (DF) to improve biohythane production. DF supplemented with 1.21 g/L MoO42- increased hydrogen yield by 14.6\% over the control (68.39 ml/g-VSfed), while FeCl3 had no effect. Furthermore, the maximum methane yields of methanogenic fermentation were 524.8 and 521.6 ml/g-VSfed with 3.63 g/L MoO42- and 0.6 g/L FeCl3 compared to 466.07 ml/g-VSfed of the control. The maximum yields of biohythane and energy were 796.7 ml/g-VSfed and 21.8 MJ/kg-VSfed with 0.6 g/L FeCl3 when the sulfate removal efficiency was 66.7\%, and H2S content was limited at 0.08\%. Therefore, adding 0.6 g/L FeCl3 is the most beneficial in improving energy recovery and sulfate removal with low H2S content.
Several studies have reported that the hydrothermal carbonization method (HTC) of agricultural waste is able to produce a solid residue with interesting properties for the adsorption of organic pollutants from contaminated water. This work represents a facile method to prepare hydrochar (HC) from pomegranate peels' waste using the microwave-assisted hydrothermal carbonization method (MHTC) at 200 degrees C for 1 h with a mass ratio of peel to water = 1:10. Activated hydrochar (AHC) was prepared by in situ chemical activation using ZnCl2 and MHTC. Several techniques have been applied to characterize the prepared samples as FTIR, XRD, TEM and SEM. The samples were investigated for their possible use as adsorbents of methylene blue (MB) dye. The results confirm the formation of amorphous hydrochar with a porous structure. The pH of zero point charge (pH(zpc)) is 4.3 and 4.6 for HC and AHC samples, respectively. The maximum adsorption capacity of HC and AHC samples are 194.9 and 12.55 mg/g (i.e., mg of adsorbate/g of adsorbent), respectively.
We optimized the production of lactic acid by Lactobacillus plantarum BL011, using acid and enzymatic soybean hull hydrolysates as cultivation media. Selection of cultivation conditions was performed in Erlenmeyer flasks, in orbital shaker at 37 degrees C and 120 rpm, pH 6.0. Plackett-Burman experimental design was performed as tool to identify the best cultivation temperature and whether medium supplementation should be necessary for further experiments. Crude yeast extract and magnesium sulfate supplementation, temperature of 30 degrees C, 48 h of cultivation, were the ideal conditions defined in batch cultivations (anaerobiosis and controlled pH), allowing for the production of 39.34 g.L-1 of lactic acid, and a productivity of 0.82 g.(L.h)(-1) at 48 h of cultivation. Fed-batch bioreactor cultivations were performed, applying 12-h linear ascending feeding strategy, using enzymatic hydrolysate containing either 90 g.L-1 or 130 g.L-1 of total sugars, resulting in a productivity above 1.5 g.(L.h)(-1) and acid lactic concentration of 58.6 g.(L.h)(-1), after 48 h of cultivation. Our results demonstrate the possibility of using this abundant waste lignocellulosic biomass hydrolysates to cultivate Lactobacillus and to obtain high concentrations of lactic acid.
This paper aims to investigate the impact of ionic liquid (ILs) pretreatment on low-grade coal for the thermochemical conversion process. Two imidazolium-based ILs, 1-butyl-3-methylimidazolium chloride {[
Several countries in the world have experienced considerable economic growth in the construction sector in recent decades, culminating in the demolition and reconstruction of large structures of reinforced concrete, that produced large amounts of solid waste. Much of this construction and demolition waste (CDW) is deposited in landfills, which generates high costs. The objective of this work is to evaluate the use of CDW as a replacement of natural sand in coating mortars. Four mortar mixtures, 1:1:6 (cement:lime:natural sand), with partial and total substitutions of the natural sand were investigated for CDW addition of 0 (reference), 25, 50 and 100 wt.\%. Physical characterization of the CDW was carried out by particle size analysis while chemical composition was disclosed by EDX. Technological properties related to mortar fluidity, mechanical strength, mass density and water absorption by capillarity as well as environmental characteristics associated with leaching and solubilization of mortars, were evaluated. In addition, the compactness of the material was verified through Rene Feret's law. The results demonstrate that the substitution of more than 25\% CDW for sand requires relatively larger amounts of water in the mortar. With regard to the degree compactness, the use of CDW improves the degree of compaction of the evaluated mortars and increase the compressive strength. However, the water absorption of the mortar increased with the levels of incorporated CDW. Therefore, to attend standard requirements for mortars, it is not possible to use CDW contents above 25\%. (C) 2020 The Authors. Published by Elsevier B.V.
Neonatal Holstein heifer (n = 72) and bull (n = 40) calves were used to study the effects of Aspergillus oryzae fermentation extract (Amaferm) on their performance and on rumen development. The starter diets were formulated to achieve Amaferm consumption of 0, .5, 1, or 3 g per calf daily. Calves were fed milk daily and allowed to consume starter and a mixture of alfalfa and bromegrass hay ad libitum. Weaning was when calves consumed 550 g of starter on 2 consecutive d. Weight gain and feed consumption were recorded weekly. Forty of the heifer calves, 10 from each treatment, were selected randomly to study the effects of Amaferm on ruminal fermentative development. Ruminal fluid samples were collected for pH, ruminal fermentation products, and for bacterial enumerations. Overall, Amaferm-supplemented calves were weaned 1 wk earlier than unsupplemented calves. They had higher total VFA, propionate, and acetate concentrations in the rumen than unsupplemented calves. Total anaerobic, hemicellulolytic, and pectinolytic bacterial counts were higher; cellulolytic bacterial counts tended to be higher for the Amaferm-supplemented calves than for controls. In general, Amaferm-supplemented calves had greater ruminal microbial activity than those not fed Amaferm.
The global generation of millions of tonnes of water treatment sludge (WTS) per day is triggering waste management problems and the up-cycling of WTS in masonry bricks is an eco-friendly solution. Effect of different dosages of WTS on the performance of clay bricks has been studied by researchers. Scant work is available regarding the performance of no-clay bricks i.e. bricks made exclusively with the WTS. This study aims to investigate the engineering performance of no-clay bricks having WTS, glass, and marble wastes. For this reason, WTS bricks are manufactured with different dosages of glass and marble wastes (i.e. 0-15\%). Mechanical, durability, thermal, and microstructural performance of all the brick specimens is explored. X-ray fluorescence results show that the collective amount of fluxing agents in WTS exceeds 9\% (similar to low refractive clay). All the bricks manufactured in this study exhibited water absorption between 5.3 and 12.6\% and can be classified as first-class and severe weather resistant bricks as per ASTM C373-18 and ASTM C62-17, respectively. The thermal conductivity and porosity of no-clay WTS bricks were observed 1.014 W/mK and 11\%, respectively. Moreover, the higher compressive strength and bulk density of all the brick specimens fulfill the international building code obligations. Furthermore, no-clay WTS bricks meet the ASTM C902 and ASTM C62-17 requirements for light vehicular traffic and severe weather-resistant bricks, respectively. Empirical relationships between the compressive strength, thermal conductivity, porosity, and density of brick specimens developed in this study can be used to predict the performance of WTS bricks. Therefore, no-clay WTS bricks having glass and marble wastes can be used to produce strong, durable, and sustainable buildings leading towards a cleaner environment and natural clay conservation. (c) 2021 Elsevier Ltd. All rights reserved.
Micro- and nanofibrillated cellulose (MNFC) was extracted from pineapple stems by acid hydrolysis, then characterized and tested in two concentrations (0.5 and 1.0 wt\%) in polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives. The modified adhesives were used to glue three tropical wood species (Vochysia ferruginea,Cordia alliodora, andGmelina arborea), and their corresponding bond strength resistance was determined. MNFC and the correspondent adhesives were characterized by TGA, FTIR, SEM, TEM, AFM, and viscosity determination. The TGA analysis of MNFC showed three decomposition reactions. The SEM, TEM, and AFM evaluations demonstrated the presence of micro- and nanosized dimensions of particles after the acid hydrolysis of pineapple stems. Adding 1 wt\% MNFC to PVAc and UF adhesives increased their thermal stability in similar manner. Viscosity diminished in both modified adhesives with MNFC; however, this reduction did not affect the adhesion properties in the tropical wood tested. MNFC added to PVAc and UF adhesives improved shear strength (SS) of the glue line in the three tropical species tested. The highest SS increase was obtained when adding 0.5 wt\% MNFC to PVAc inV. ferruginea, and 1 wt\% MNFC concentration in the case ofC. alliodoraandG. arborea. In the case of UF adhesives, the application of 1 wt\% MNFC produced significant differences in SS for the three tropical species studied.
Biochar is a potential medium for carbon storage, so its production and storage have been considered as is a crucial route to effectively achieve negative CO2 emissions. Meanwhile, torrefaction is a thermochemical conversion process for producing biochar. Biochar is featured by its hydrophobicity, which makes it different from its parent biomass with hygroscopicity and is conducive to material storage. To evaluate the hygroscopic transformation of biomass from torrefaction, two woody biomass materials of poplar (hardwood) and fir (softwood) are torrefied at temperatures of 200-230 degrees C, and the variations of color, equilibrium moisture content, and contact angle of raw and torrefied samples are examined. The results indicate that the total color difference of torrefied woods increases linearly with increasing mass loss. The hygroscopicity reduction extent in torrefied fir is higher than in torrefied poplar, and can be increased by up to 57.39\% at 230 degrees C. The tests of the contact angle suggest that the hygroscopicity of the raw woods is evidently exhibited, whereas the angles of the torrefied woods are in the range of 94-113, showing their hydrophobic surfaces (> 90 degrees). The decarbonization, dehydrogenation, and deoxygenation phenomena of the biomass during torrefaction are also analyzed. It is found that the three indexes can be correlated well by the total color difference and hygroscopicity reduction extent. A comprehensive study on the improvement of hydrophobicity of produced biochar has been performed, which clearly shows the potential of carbon storage and negative CO2 emissions by biochar.
The present work describes an alternative process for glucose oxidation via photoelectrocatalytic technique using Ti/TiO2 nanotubes as photoanodes. Under optimum experimental conditions, which entailed 10.0 mM glucose in 0.1 M Na2SO4, pH 6.60, E-app = 1.5 V and UV irradiation we were able to convert 78\% of glucose following 180 min of photoelectrocatalysis. Out of that, only 28\% was in effect, converted to CO2 as detected by total organic carbon removal. During the course of the process, a large part of this glucose was found to be transformed into products among them including Arabinose, Arabinitol, 4-ketoglicose, glucohexodialdose, Glucone-delta-Lactone, 6-deoxiglucose and Gluconic Acid, where this detection was aided by ion-exchange chromatography with amperometric detection and gas chromatography-mass spectra. The results thus essentially demonstrate that photoelectrocatalys can be considered a suitable alternative in fostering glucose conversion, in aqueous medium, to high added value products using a relatively simple and economic method. (C) 2016 Elsevier Ltd. All rights reserved.
Green construction materials have emerged as viable options to cope with the sustainability challenges set by the global communities without compromising the technical merits. Agro-industrial wastes have been utilized as alternative components in manufacturing construction products. In this vein, burnt clay bricks (CBs) is one of the novel and viable waste disposal strategy. Therefore, the primary focus of this research is to examine the impacts of agro-industrial wastes, such as sludge waste (SW), steel slag (SS), wood ash (WA), and banana ash (BA) on various physical, mechanical, and microstructure characteristics. The green CBs were prepared by admixing the wastes at a 5\%, 10\%, 15\%, and 20\% dosage. The binary blended CBs were dried under the sun for 7 days before being fired at 900 degrees C for 3 hrs. The CBs containing SW, WA, and BA exhibited lower compressive strengths of similar to 67\% than the control and SS blended specimens depending on the chemical composition and particle size distribution of the source material. The microstructural analysis of the CBs incorporating the wastes tented to improve with the addition of waste precursors and governed by the Ca/Si ratio. The outcomes revealed the potential of attaining reduced bulk density for the light-weight and cost-effective constructions with low volume (5\%) replacement of studied wastes in the clay mixture. The scanning electron microscopic (SEM) analysis revealed a relatively compact matrix of the control and SS-based specimens which tended to improve the engineering properties of developed CBs.
Xylans play an important role in dispersing and lubricating cellulose fibrils in lignocellulosic plant cell walls. However, the effect of acetylation on the dispersing and emulsifying properties of xylan is still unclear. In this study, we show that the natural degree of acetylation is vital to ensure xylan an excellent water solubility and emulsifying ability. Alkali extracted xylans were artificially acetylated to degree of substitution (DSAc) between 0.12 and 2.00, while the DMSO extracted originally acetylated xylan (OAX) shows a DSAc of 0.18. Artificially acetylated xylans (AX) with DSAc value similar to OAX shows water solubility and emulsifying ability similar to those of OAX and the best among all the AX samples with different DSAc. They demonstrate excellent emulsifying properties with an emulsifying activity of similar to 1.3 and an emulsion cream index of similar to 5 \%. AX with the natural DSAc value also demonstrates strong barrier effects in preparing lutein delivery emulsions.
The effects of using 100\% larch bark (Larix decidua Mill) as a raw material for composite boards on the thermophysical properties of this innovative material were investigated in this study. Panels made of larch bark with 4-11 mm and 10-30 mm particle size, with ground bark oriented parallel and perpendicular to the panel's plane at densities varying from 350 to 700 kg/m(3) and bonded with urea-formaldehyde adhesive were analyzed for thermal conductivity, thermal resistivity and specific heat capacity. It was determined that there was a highly significant influence of bulk density on the thermal conductivity of all the panels. With an increase in the particle size, both parallel and perpendicular to the panel ` s plane direction, the thermal conductivity also increased. The decrease of thermal diffusivity was a consequence of the increasing particle size, mostly in the parallel orientation of the bark particles due to the different pore structures. The specific heat capacity is not statistically significantly dependent on the density, particle size, glue amount and particle orientation.
Supercritical methanol was used for one put biodiesel production from microalgae biomass. Fatty acid methyl esters (FAMEs) hydrocarbons, and oxygenates were produced in catalytic and non-catalytic procedures in the presence and absence of subcritical water. The CaO nanoparticles were synthetized using photochemical method on TiO2. Addition of catalyst and water to supercritical methanol could increase total product yield up to 51.6\%, FAMEs yield up to 28.1\%, hydrocarbons yield up to 2.5 times, and oxygenates yield up to 3.8 times. No CaO was detected in products and no color change occurred for product over time. The effects of catalysts and subcritical water on quality and quantity of products were described using reaction mechanisms. Accordingly, it can be proposed that water in subcritical condition dissolves cell wall of biomass and facilitates mass transfer of bio-oil to catalyst surface. In addition, it produces intermediates on catalyst surface that can accelerate FAMEs and oxygenates production.
Wood pulverised using a ball mill was dissolved in an alpha-keto acid, pyruvic acid, and two aldehydic carboxylic acids, namely glyoxylic acid and formic acid, at room temperature. Viscosity and optical transmittance analyses revealed that the wood particles dissolved in glyoxylic acid and formic acid in several hours, while they dissolved in pyruvic acid in several days. Size exclusion chromatography demonstrated that substances with number average molecular mass exceeding 10(5) were present in every solution. Incubation of these carboxylic acids with methanol produced the corresponding ester and/ or (hemi) acetal derivatives, suggesting that the dissolution mechanism involves the substitution of hydroxyl groups in biomass. After dissolution, all solutions demonstrated non-Newtonian fluid behaviour with a non-Newtonian index n ranging from 0.41 to 0.72. When the dissolution time increased, the non-Newtonian index of the formic acid solution increased towards the value for a Newtonian fluid (n = 1). This rise was accompanied by partial depolymerisation. Evaporation of the wood solution gave a smooth transparent film. Using the water-immiscible solvent 2-methyltetrahydrofuran (2-MeTHF), the formic acid solution was separated into cellulosic porous solids, lignin-rich 2-MeTHF-soluble fraction and other components at room temperature. The dissolution of woody biomass at room temperature creates a new biorefinery process for the conversion of wood components in various solution reactions. In particular, in this study, pyruvic acid, which plays a central role in the metabolism of living organisms, is used as a new solvent for wood, thus bridging biochemistry and wood biorefinery.
Xylooligosaccharides (XOS) are nondigestible compounds of great interest for food and pharmaceutical industries due to their beneficial prebiotic, antibacterial, antioxidant, and antitumor properties. The market size of XOS is increasing significantly, which makes its production from lignocellulosic biomass an interesting approach to the valorization of the hemicellulose fraction of biomass, which is currently underused. This review comprehensively discusses XOS production from lignocellulosic biomass, aiming at its application in integrated biorefineries. A bibliometric analysis is carried out highlighting the main players in the field. XOS production yields after different biomass pretreatment methods are critically discussed using Microsoft PowerBI (R) (2.92.706.0) software, which involves screening important trends for decision-making. Enzymatic hydrolysis and the major XOS purification strategies are also explored. Finally, the integration of XOS production into biorefineries, with special attention to economic and environmental aspects, is assessed, providing important information for the implementation of biorefineries containing XOS in their portfolio.
Water and chemical overconsumption is one of the technical challenges for cellulosic ethanol production. To address this issue, a facile process, where Ca(OH)(2)-pretreated corn stover slurry is subjected to pH adjusting with H2SO4 for ethanol fermentation by C6 (scenario I) or C6/C5 (scenario II) yeast, is proposed. This study demonstrates its experimental feasibility for ethanol production without solid-liquid separation and detoxification, thus effectively reducing the consumption of water and chemicals. Technoeconomic analysis shows that total capital investment ranges from \$127.86 million to \$134.82 million with a production capacity of 90 Mt/h for 7920 h annually. Raw material (43.22-44.62\%) and utility (35.49-37.23\%) costs play important roles in annual operating costs. The pretreatment and fermentation section contributes \$2.12/gal for scenario I and \$1.61/gal for scenario II to the net unit production cost of ethanol. The ethanol minimum selling prices (MSP) of \$4.01/gal for scenario I and \$3.16/gal for scenario II are reached with an internal rate of return of 10\%. Sensitivity analyses indicate that the costs of corn stover and water for cooling are the dominant elements affecting ethanol MSP.
In this study, heavy bio-oil (HB) and apricot shell (AS) were used as raw materials to produce biochar by copyrolysis in a tube furnace. Three operational factors were assessed, namely pyrolysis temperature (400-700 degrees C), residence time (5-20 min) and percentage of HB (0-100\%), with the effects on the yield and properties of biochar comprehensively investigated using a response surface methodology. Results showed that the mass yield, fixed carbon content, carbon content, and high heating value (HHV) of co-pyrolysis biochar (550 degrees C, 12.5 min, and an AS/HB mass ratio of 1:1) were 29.33\%, 81.84\%, 82.91\%, and 32.97 MJ/kg, respectively. The experimental values for the co-pyrolysis biochar were 1.52\%, 5.30\%, 1.82\%, and 1.12 MJ/kg higher than their corresponding theoretical values, respectively. However, the oxygen content of co-pyrolysis biochar was 1.71\% lower than the theoretical value. Meanwhile, the C/H ratio of biochar improved with increasing pyrolysis temperature, residence time and percentage of HB, indicating higher biochar aromaticity. The evolution of surface functional groups indicated that an increase in pyrolysis temperature and residence time reduced the intensity of C--O and C-O absorption peaks, while an increase in the percentage of HB enhanced the intensity of the C-O absorption peak of biochar. In general, compared to the pyrolysis of HB and AS alone, copyrolysis of HB and AS exerted a synergistic impact, improving the mass yield and fuel quality of biochar. Finally, the relationships between properties (mass yield, element content, proximate analysis parameters, and HHV) and the three varied factors were established, providing guidance for effective upgrading of biochar by co-pyrolysis of HB and biomass.
beta-Glucosidases are important enzymes with significant prospects in the industrial biotechnology, including their use in biomass hydrolysis for bioethanol production. In this study, the use of canola meal as carbon source for beta-glucosidase production by a Trichoderma viride strain in submerged fermentation was evaluated by applying central composite design and response surface methodology to optimize the production process. This statistical approach was also used to improve the passion fruit peel hydrolysis by T. viride crude extract. The model developed 3.6-fold increased beta-glucosidase activity. The culture conditions that resulted in the highest beta-glucosidase levels were a substrate concentration of 2.9 \%, pH of medium 4.2 and cultivation time of 206 h. The beta-glucosidases produced under optimal conditions showed attractive properties for industrial applications, such as activity at high temperatures and stability at 55 A degrees C and over a wide pH range. In addition, the enzymatic hydrolysis of passion fruit peel by T. viride crude extract was very promising, resulting in glucose yields of 66.4 \%. This study, therefore, presents canola meal as an inexpensive and attractive substrate for the production of microbial beta-glucosidases.
MixAlco (TM) consolidated bioprocessing (CBP) employs a mixed culture of terrestrial microorganisms to anaerobically ferment waste streams (e.g., animal manure, agriculture residues) into mixed carboxylate salts that can be further chemically converted to commodity chemicals (e.g., acetic acid, acetone) and liquid transportation fuels (e.g., ethanol, mixed alcohols, bio-gasoline). For countercurrent fermentations of 60\% swine manure/40\% lime-treated corn stover at 55 degrees C, the highest acid productivity {[
Due to environmental concerns, as well as its exceptional physical and mechanical capabilities, biodegradability, and optical and barrier qualities, nanocellulose has drawn a lot of interest as a source of reinforcing materials that are nanometer sized. This article focuses on how to manufacture cellulose nanomaterials from cotton by using different types of acids such as H2SO4 and HCI in different concentrations and in the presence of enzymes such as cellulase and xylanase. Two different types of bleaching methods were used before acid and enzyme hydrolysis. In the first method, cellulose was extracted by bleaching the cotton with H2O2. In the second method, NaOCl was utilized. For both methods, different concentrations of acids and enzymes were used to isolate nanocellulose materials, cellulose nanocrystals (CNC), and cellulose nanofibrils (CNF) at different temperatures. All obtained nanocellulose materials were analyzed through different techniques such as FT-IR, Zeta potentials, DLS, Raman spectroscopy, TGA, DSC, XRD, and SEM. The characteristic signals related to cellulose nanocrystals (CNC) were confirmed with the aid of Raman and FT-IR spectroscopy. According to the XRD results, the samples' crystallinity percentages range from 54.1\% to 63.2\%. The SEM image showed that long fibers break down into small fibers and needle-like features are seen on the surface of the fibers. Using different types of bleaching has no significant effect on the thermal stability of samples. The results demonstrate a successful method for synthesizing cellulose nanofibrils (CNF) from cotton through enzymatic hydrolysis, but the results also demonstrated that the choice of bleaching method has a significant impact on the hydrodynamic properties and crystallinity of both CNC and CNF samples.
Enzyme treatment is a potential strategy for producing cellulose fibrils but its evolution of the mesoscopic and microcosmic structures is not fully understood. In this work, the effect of the properties and microstructures of cellulose bleached hardwood kraft pulp (BHKP) subjected to different enzyme treatment times (0-10 h) on further fibrillation was explored by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results showed that the enzyme treatment did not change the crystal structure of cellulose but destroyed the intermolecular and intramolecular hydrogen bonds, leading to the increase of the crystal index and size. A thorough investigation on the relation between treatment and evolution of inter-/intra-molecular H-bonds in cellulose including content and cleave sequence of H-bonds was conducted by FTIR peak fitting, second derivative analysis and generalized two-dimensional correlation spectroscopy (2DCOS). Compared to intramolecular H-bonds, the intermolecular H-bonds was first broken with a significant decrease in content. In addition, enzyme treatment could promote the peeling of fibrils, and various properties such as yield, water retention value, aspect ratio, and degree of polymerization, etc. were gradually reduced over time relative to the original material, these discoveries provide a theoretical support to a more effective treatment method for the commercial production of cellulose fibrils.
The novel and facile preparation of magnetically interconnected micro/macroporous structure of monolithic porous carbon adsorbent (MPCA) were designed and presented herein. The synthesis was achieved via conventional freeze-drying and pyrolysis processes. In this study, sodium alginate and wasted black liquor were employed as starting precursors. Sodium alginate acts as a template of materials, whereas black liquor, the wasted product from the paper industry with plentiful of lignin content and alkaline solution, played an essential role in the reinforcement and activation of porosity for the resulting materials. Moreover, both the precursors were well dissolved in Fe3+ solution, providing a simple addition of a magnetic source in a one-pot synthesis. The interconnected micro/macroporous structures were generated through freeze-drying and, subsequently the pyrolysis process. The obtained cylindrical-shaped monolithic porous carbon adsorbent (MPCA-700) showed high mechanical stability, a high BET specific surface area (902 m(2)/g). Such aforementioned features were considered suitable to make the synthesized monolith as an adsorbent for the removal of heavy metal ions. The maximum adsorption capacity of MPCA-700 towards Pb2+ ions was 76.34 mg/g at pH 5. The adsorption studies illustrated that adsorption kinetics and isotherm perfectly fitted with the pseudo-second-order kinetics model and Langmuir isotherm, respectively. This work presents a promising protocol to reduce the overall costs in the preparation of renewable adsorbents with good adsorption efficiency and regeneration.
The xylan recovered from alkaline black liquor (ABL) of oil palm frond (OPF) has the potential to be converted into value-added products that hold promise, especially for the pharmaceutical industry. This research highlights the maximum xylan relative recovery extracted from ABL by varying the extraction parameters such as the concentration of sodium hydroxide (NaOH) (2 to 10\%) (w/v), reaction temperature (60 to 140 degrees C), and extraction time (30 to 150 min), followed by a 2-stage precipitation method. 6 M of hydrochloric acid (HCl) was used in the first stage to separate the lignin sub-fraction (LF) from the ABL, and 95\% ethanol was used in the second stage to obtain xylan sub-fraction (XF). The optimal condition of 6\% NaOH (w/v), 100 degrees C, and 60 min was able to recover 84\% of xylan, with low contamination of lignin (7.7\%) and glucan (0.3\%) in XF, while higher contamination of lignin (19.3\%) and glucan (10.9\%) with lower amount of xylan (8.8\%) were found in LF. The amount of lignin and glucan in LF through the first precipitation was higher than in XF from the second precipitation, leaving remaining fraction of XF mainly composed of xylan. In sum, the developed process reduced the alkali consumption while retaining a high xylan recovery under mild process conditions.
An integrative simultaneous saccharification and fermentation (SSF) modeling is a useful guiding tool for rapid process optimization to meet the techno-economic requirement of industrial-scale lignocellulosic ethanol production. In this work, we have developed the SSF model composing of a metabolic network of a Saccharomyces cerevisiae cell associated with fermentation kinetics and enzyme hydrolysis model to quantitatively capture dynamic responses of yeast cell growth and fermentation during SSF. By using model-based design of feeding profiles for substrate and yeast cell in the fed-batch SSF process, an efficient ethanol production with high titer of up to 65 g/L and high yield of 85 \% of theoretical yield was accomplished. The ethanol titer and productivity was increased by 47 and 41 \%, correspondingly, in optimized fed-batch SSF as compared to batch process. The developed integrative SSF model is, therefore, considered as a promising approach for systematic design of economical and sustainable SSF bioprocessing of lignocellulose.
As one of the three main components of lignocellulose (cellulose, hemicellulose and lignin), the physical and chemical properties of hemicellulose determine the reaction and solubility characteristics of hemicellulose to the commonly used agents for component separation, and the preferential extraction of hemicellulose is an important way to realize the high value utilization of biomass. Herein, an efficient new method of hemicellulose extraction by sodium perborate-assisted potassium hydroxide pretreatment was proposed. The extraction of hemicellulose with high whiteness and molecular mass under lower temperature conditions was achieved. The effects of chemical dosage, temperature and time on the separation efficiency and characteristics of hemicellulose were comprehensively investigated. The results showed that sodium perborate could greatly improve the separation efficiency of hemicellulose. Under the optimal process conditions of 10wt\% KOH combined with 3\%NaBO3 at 85 celcius for 3 h, the removal rate of hemicellulose could reach 83.34\% and the recovery rate was 64.50\% Meanwhile, the extracted hemicellulose possessed significantly low color value and high molecular (23.35 kDa). The preferential removal of hemicellulose not only provides a raw material guarantee for the high-value utilization of hemicellulose but also facilitates the opening of lignocellulosic cell wall channels, which is conducive to the further processing and utilization of biomass feedstock.
To assuage global consumer demand for energy, there is a need for increased biofuel production. Flash pyrolysis is an important technique for biomass conversion into eco-friendly biofuels. This review discusses the research progress and key findings made over the years on the flash pyrolysis of biomass. Flash pyrolysis oil yields can be as high as 60-75 wt\% at optimised conditions. For the process to be effective, temperature, heating rate and residence time would be within the range of 450-600 degrees C,10(3) - 10(4) degrees C/s and < 1 s. Flash pyrolysis oil is characterised by high water content (usually > 15 wt\%). The main pyrolysis products of lignin part biomass are phenols. The phenolic part includes phenols, hydroxylphenols, meothoxyphenols, dimethoxyphenols. Flash pyrolysis products of biomass (as with other pyrolysis types) must be upgraded before use. They are unstable, re-polymerised and are not miscible with hydrocarbons. The future of the technology is promising as products obtained can serve as better feedstock for other re-refining processes (compared to other pyrolysis process types). Furthermore, it is faster and can handle higher feedstock volumes at similar reactor volumes and process intricacies. Due to the advantages of product yield, it is an important technology that should be explored for energy conversion of biomass and can also serve as a solid waste management technique. {[
The conversion of lignocellulose into its building blocks and their further transformation into valuable platform chemicals (e. g., furfural) are key technologies to move towards the use of renewable resources. This paper explored the disentanglement of lignocellulose into hemicellulose-derived sugars, cellulose, and lignin in a biphasic solvent system (water/2-methyltetrahydrofuran) using phosphoric acid as recyclable catalyst. Integrated with the biomass fractionation, in a second step hemicellulose-derived sugars (mainly xylose) were converted to furfural, which was in situ extracted into 2-methyltetrahydrofuran with high selectivity (70 \%) and yield (56 wt \%). To further increase the economic feasibility of the process, a downstream and recycling strategy enabled recovery of phosphoric acid without loss of process efficiency over four consecutive cycles. This outlines a more efficient and sustainable use of phosphoric acid as catalyst, as its inherent costs can be significantly lowered.
The aim of this work is to crack the used cooking oil in a fixed bed cracking unit using impregnated CaO/SBA-15 catalyst to yield liquid hydrocarbons with high \% of biogasoline (BioG)fraction. Further, to investigate the capacity of the biogasoline fraction as well as the bio gasoline blends with fossil gasoline in increasing its efficiency. The porous morphology, pore distribution and surface area, elemental composition and phase formation of catalysts were analysed by Scanning electron Microscopy, Surface area analyser and X-ray diffraction techniques. All the synthesized materials were crystalline and least changes were observed with incorporation of CaO on SBA-15. The morphology of the materials were as expected without much agglomeration. SBA-15 exhibited fair surface area of around 1300 m(2)/g and discrete pores gas chromatography mass spectrometry (GC-MS). Among the catalysts, the composite material, CaO/SBA-15 (4 wt\%) efficiently cracked 97\% of used cooking oil into 70\% liquid products and 69.7\% of biogasoline which was confirmed using gas chromatography-mass spectrometry (GC-MS). BioG showed a good Calorific value of 10000 MJ/Kg which was comparable to that of petroleum fuel. Results of the engine test indicated that using biogasoline-gasoline blended fuels, torque output and fuel consumption of the engine increased when compared to gasoline; CO and SO2 emissions decreased largely due to the oxidation, CO2 emission increased because of the improved combustion and NOX emission from bio gasoline blends was low than gasoline.
Burnt clay bricks are commonly used in construction across the globe. The objective of this study is to explore the potential of using waste glass sludge (WGS) as a secondary material in clay brick manufacturing. WGS was collected during industrial-scale cutting and polishing of glass. Brick specimens were manufactured using various dosages (i.e.,5, 10, 15, 20, and 25\% by clay weight) of WGS at an industrial brick kiln plant. A range of mechanical and durability tests were performed on the bricks thus produced to quantify their performance. Clay bricks incorporating WGS exhibited higher compressive and flexural strength as compared with that of control traditional clay bricks. The unit weight of bricks was reduced owing to WGS addition, which can lead to lighter and economical structures. Furthermore, the resistance against efflorescence, sulfate attack, and freeze-thaw was enhanced for all the clay bricks incorporating WGS. Scanning electron microscopy indicated a well-bonded and fused structure of brick specimens incorporating WGS. The findings demonstrate that WGS can enhance the physical and mechanical properties of clay bricks, leading toward more economical and sustainable construction.
In this study, catalytic activity and deactivation mechanism of a carbon-based solid-acid catalyst in the esterification of oleic acid and methanol were investigated. The experimental results showed that the S150-4 catalyst, prepared by sulphonating at 150 degrees C for 4 h, yielded the highest sulfonic acid density. The conversion yield reached 97.98\% under the optimum esterification conditions (i.e. catalyst loading, 10 wt \%; methanol/oleic acid molar ratio, 8:1; reaction temperature, 65 degrees C; reaction time, 8 h) and decreased to 79.19\% after four cycles. In the first batch of esterification, the formation of sulfonic esters was the main reason for the deactivation of the catalyst, whereas the leaching of sulphur was the main contributor in the second to fourth batches. Therefore, it is believed that reducing the leaching of sulphur and the formation of sulfonic esters by changing the addition method of methanol is an effective method to extend the service life of the catalyst. (C) 2020 Elsevier Ltd. All rights reserved.
This work aimed to characterize the fuel properties and to evaluate the kinetics of thermal decomposition of defective coffee beans (DCB). Three thermogravimetric-based methods were evaluated: Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS) and Friedman. The results showed that DCB presented low activation energy and that the evaluated mathematical models, although satisfactory for describing thermal decomposition in inert atmospheres, did not provide a satisfactory description of the oxidizing process. The enthalpy values indicated that the energy differences between the reagents and the activated complex are related directly to the activation energies. Pre-exponential factors indicated first-order reactions. The immediate analysis and the lignocellulosic contents indicated a biomass with low levels of humidity and ashes, high carbon and volatile concentrations, besides thermal stability. The obtained calorific value was 19.39 MJ/kg. The overall results obtained in the present study indicate that this biomass has the potential to be used as a solid biofuel. (C) 2019 Elsevier Ltd. All rights reserved.
The main goal of this work is the production of a biopesticide through solid-state fermentation of biowaste digestate inoculated with Bacillus thuringiensis (Bt) at pilot scale using different configurations of reactors. Fermentations were carried out using insulated and non-insulated, stirred and non-stirred reactors at different scales (10, 22 and 100 L) in order to assess the influence of the reactor configuration on the biopesticide production process. A maximum temperature of 60 degrees C was reached in 10-L insulated non-stirred reactors where increments of Bt viable cells and spores with respect to initial values of 1.9 and 171.6 respectively, were attained. In contrast, when temperature was regulated by using 22-L non-insulated stirred reactors the increment of viable cells and spores were 0.8 and 1.9, respectively, at a stable temperature of 27 degrees C. When the non-insulated stirred reactor was scaled up to 100-L, the increase of viable cells and spore counts were 1.2 and 3.8 respectively, with an average temperature of 28 degrees C. These results demonstrated that the election of a proper reactor configuration is important when considering the development of a new SSF process, especially when dealing with non-conventional substrates as digestate. (C) 2019 Elsevier Ltd. All rights reserved.
Cellulose nanocrystals (CNCs) have a promising application in many advanced products, such as biomedical applications and hydrogels. In this research, industrial cotton waste was treated using alkali and bleaching to eliminate hemicellulose, lignin, and other amorphous contents. The efficiency of these treatments was proven by chemical compositions analysis, which showed an increase in cellulose percentage with the progression of treatments. Fibers were analyzed by X-ray diffraction, thermogravimetric, and Scanning Electron Microscopy (SEM). CNCs were then prepared by acid hydrolysis using different sulfuric acid concentrations (50 wt\%, 60 wt\% and 64 wt\%) and two reactions time (60 min. and 75 min.) resulting in six CNCs suspensions. CNCs were analyzed by X-ray diffraction, thermogravimetric, zeta potential, and Transmission Electron Microscopy (TEM). CNCs obtained exhibited a good crystallinity index varying from 75 to 81\% and thermal stability between 146 degrees C and 200 degrees C. TEM analysis showed that sulfuric acid concentration influenced in CNCs length (105 nm-5880 nm). By analyzing all results, the optimal parameters for acid hydrolysis were 64\% (w/w) of acid concentration combined with 60 min. of reaction time. The preparation of CNCs in this work showed some prospects of using untraditional industrial cotton waste as an advanced material. (C) 2018 Published by Elsevier B.V.
This study involved preparation and modification of Saccharum officinarium as adsorbent used for the removal of chromium (VI) ions in a batch process. The adsorbent was modified with oxalic acid for improved performance of the adsorbent by increasing the surface area of the adsorbent. Surface morphology of the adsorbents was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), while Fourier transform infrared (FT-IR) analysis was carried out before and after the adsorption of Cr (VI) ions to determine the participating functional group in the processes. The optimum adsorption was attained at pH 2 and contact time of 180 min with efficiency of adsorption of 56.7 and 92.6\% onto RSO and MSO, respectively. The adsorption capacity increases with increase in initial metal ion concentration of the sorption mixture. The isotherms studies indicate that the experimental data were best fitted to Freundlich, Langmuir, and Sips models with R-2 = 0.999 for adsorption of Cr (VI) ions onto raw S. officinarium (RSO) and modified S. officinarium (MSO). The maximum adsorption capacity obtained were 227.27 and 243.90 mg{*
Oil palm empty fruit bunch (EFB) pulp with the highest cellulose content of 83.42\% was obtained from an optimized process of acid pretreatment (0.5\% v/v H2SO4), alkaline extraction (15\% w/w NaOH), and hydrogen peroxide bleaching (10\% w/v H2O2), respectively. The EFB cellulose was carboxymethylated, and the obtained carboxymethyl cellulose (CMC) was readily water-soluble (81.32\%). The EFB CMC was blended with glycerol and cast into a composite film. Lignin that precipitated from the EFB black liquor was also incorporated into the film at different concentrations, and its effect on the UV-blocking properties of the film was determined. Interestingly, the EFB CMC film without lignin addition completely blocked UV-B transmittance. The incorporation of lignin at all concentrations significantly enhanced the UV-A blocking and other physical properties of the film, including the surface roughness, thickness, and thermal stability, although the tensile strength and water vapor permeability were not significantly affected. Complete UV-A and UV-B blocking were observed when lignin was added at 0.2\% (w/v), and the film also exhibited the highest antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals with an half-maximal inhibitory concentration (IC50) value of 3.87 mg mL(-1).
Microalgae are likely to emerge as a sustainable source of biomass which can be utilized as food, feed, and fuel. Most of the valuable products in the microalgae are present intracellular. Microalgae cell wall is rigid and mainly composed of cellulose. Hence, it is essential to disrupt cells to extract intracellular products. Probe ultrasonication (US) and hydrodynamic cavitation (HC) were optimized for their operating parameters and various pre-treatments to obtain maximum cell disruption efficacy. Optimum conditions for maximum cell disruption using US were: solid load (1\% w/v), duty cycle (80\%), power input (54 W) and the US time 90 min. After pretreatment with 0.5\% w/v sodium hydroxide; the time required for the maximum cell disruption using US was reduced to 50 min. Optimum conditions for the maximum cell disruption using HC were cavitation device orifice over venturi, time (180 min), pressure (5 bar) and solid load (0.45\% w/v). After pre-treatment with 0.5\% w/v sodium hydroxide time required for maximum cell disruption using HC was reduced to 105 min. Further, the energy required for cell disruption using US and HC was calculated and, it was found that HC was significantly more energy efficient and scalable treatment for microalgae cell disruption.
In second-generation bioethanol production, pretreatment and saccharification have been considered one of the most expensive steps. Thus, we present an approach to improve bioethanol yield by using surfactant con-comitantly with corncob pretreatment and saccharification. A response surface methodology (RSM) evaluated the Tween 80 (0\%, 5.0\%, and 10.0\% w/w), in both corncob pretreatment and saccharification, and the enzyme dosage (CellicCTec2: 5.0, 17.5, and 30.0 FPU/g(dry matter)) on enzymatic digestibility of the acid pretreated biomass. According to the results, higher glucose yields (similar to 80-85\%) could be obtained by reducing the highest enzyme dosage to 41.67\% concomitantly by reducing the Tween 80 to 34.2\% or 63\% by adding it (10\% w/w) into only the pretreatment or saccharification, respectively. The RSM suggested applying enzyme dosage between 17.5 and 25.5 FPU/gg(dry matter) associated with the highest Tween 80 amount to improve glucose yield. For statistical validation model, the maximum glucose (80.54\%) and xylose (70.66\%) yields were obtained for 10.0\% of surfactant in both pretreatment and saccharification (25.50 FPU/gg(dry matter)). The hydrolysate was supplemented and fermented by Scheffersomyces stipitis CBS 6054. This yeast fermented the sugars glucose (98.95\%), xylose (64.90\%), and cellobiose (60.12\%) efficiently into ethanol with high yield (0.37 g/g) and volumetric productivity (1.02 g(ethanol)/L.h).
Hemp is a good option for polyethylene additives because of its high cellulose and fibrous content. This study aims to modify natural hemp fibers with the maleic anhydride/ionic liquid method, manufacture the composites, and compare the thermal and mechanical properties of natural hemp fiber and hemp cellulose. In this study recycled polyethylene as a binder, and filling ratios between 0 and 50 (wt/wt)\% are investigated as a parameter. Differential scanning calorimeter and thermomechanical analysis were performed, and it was determined that the coefficient of thermal expansion from 973 to 147 ppm/K. It was determined that the strength of composite materials obtained from cellulose fibers with maleic anhydride/liquid ionic modification improved by around 20\% from 19.5 to 24.4 MPa. In addition, as a result of scanning electron microscope analyses performed on the fractured surfaces, it was determined that the pressure, temperature, and time were suitable for producing composite materials. This work shows the potential of recycled polyethylene/ hemp composites as a sustainable green material with simple fabrication procedure and useful mechanical and thermal properties.
Eucalyptus sawdust is a forest residue that, through a biorefinery approach, can be used to manufacture value-added products in the pulp and paper industries as well as to produce a biofuel. This study examines the suitability of a sequential thermochemical pretreatment that uses processes and reagents commonly utilized in the pulp and paper industry to separate valuable biomass components from eucalyptus sawdust and increase its enzymatic digestibility for ethanol production. The research strategy was based on a forest biorefinery that can be integrated into an existing industrial plant for the production of cellulose pulp. A combination of alkaline solutions was evaluated to obtain an extract rich in tannins and intended to be used in the formulation of wood adhesives. A second alkaline treatment was used to recover lignin and hemicellulose components and improve cellulose digestibility. The cellulose fraction was fermented using three commercial Saccharomyces cerevisiae yeasts (Thermosacc (R), PE-2, and CAT). Different process configurations (separate hydrolysis and fermentation (SHF), pre-saccharification followed by simultaneous saccharification and fermentation (PSSF), and simultaneous saccharification and fermentation (SSF)) at 16\% (w/v) solid loading by Thermosacc (R) yeast were also studied. Thermosacc (R) yeast enabled higher ethanol production than the other strains but resulted in similar productivity. The two-stage alkaline pretreatment of eucalyptus sawdust was successful in recovering 34 g of tannins, 56 g of xylo-saccharides, 16 g of acetic acid, and 90 g of lignin and produced 152 g of ethanol from 1 kg of dry eucalyptus sawdust.
The demand for biochar has increased over time due to its wide range of applications in various industries. Biochar, which is the solid product of the thermochemical conversion of biomass, has been synthesized using different reactor-based technologies. One such technology is top-lit updraft (TLUD) technology. This study is a review of published literature that discusses trends in the utilization of the TLUD technology, focusing on biochar production. This study also evaluated the principles of TLUD technology. The properties and applications of TLUD-based biochar were also discussed. In comparison with other technologies, TLUD technology is characterized by higher thermal efficiency, simplicity of starting the fuel, low smoke emission, and high biochar yield. It was observed that the use of TLUD technology resulted in the production of high-quality biochar with a variety of characteristics, which has been utilized as an adsorbent for wastewater treatment, in the agricultural sector to increase soil nutrients, and as a solid fuel. The concept of semi-batch-fed TLUD technology was also introduced in this study to enhance the efficiency and output of the batch-fed TLUD configuration that has been in use. Some knowledge gaps in the study could be addressed by future studies on the use of this technology.
A waste material with practically no cost, durian peel (DP) was studied for its ability to remove Basic blue 3 (BB3) from aqueous solutions. Batch kinetic studies were carried out to study the adsorption characteristics under various experimental conditions. The optimum pH for the dye removal occurred in the pH range of 3-10. Adsorption was found to be concentration dependent. The kinetics of dye adsorption fitted a pseudo-second order rate expression. Both Langmuir and Freundlich models appeared to provide reasonable fittings for the adsorption data of BB3 on DP. Application of Langmuir isotherm indicated that under the experimental condition of room temperature (25 +/- 2 degrees C) with natural pH of the dye solution and shaken at 150 rpm, the maximum adsorption capacity of DP for BB3 was 49.50 mg g(-1). The percentage uptake of BB3 increased with the increase in temperature. Adsorption of BB3 was found to be endothermic and various thermodynamic parameters were evaluated using van't Hoff plot.
The chemically activated biochar was produced through the pyrolysis of rice husk. Thermal gravimetric and elemental analysis were conducted to characterize the raw rice husk. The activated biochar product underwent evaluation through SEM, BET and, FT-IR analysis. This cost-effective activated carbon was utilized as an adsorbent for the elimination of environmental pollutants. At a temperature of 25 \& DEG;C, the activated biochar product exhibited an impressive maximum CO2 adsorption capacity of 152 mg/g. This exceptional performance can be attributed to its notable surface area and porosity, measuring at 2,298 m(2)/g and 0.812 cm(3)/g, respectively. This product was also utilized to remove methyl red (MR) dye from an aqueous solution. The optimal parameters for the removal of MR were determined as follows: a pH of 6.0, a temperature of 25 \& DEG;C, an initial MR concentration of 50 mg/L, and an adsorbent dosage of 0.4 g/L. At a duration of 140 min, the system attained its maximum equilibrium adsorption capacity, reaching a value of 62.06 mg/g. Furthermore, the calculated maximum MR removal efficiency stood at an impressive 99.31\%. The thermodynamic studies demonstrated that the MR removal process was spontaneous, exothermic, and increased randomness. Kinetic studies suggested that the pseudo-second-order model can fit well. Novelty statementRice is the staple food for a significant portion of the world's population. Rice husk, which is released during the production and processing of rice, is one of the most important agricultural wastes worldwide. In this study, low cost activated carbon was produced by converting renewable resource such as rice husk biomass into a product with high added value. The resulting product, with its high surface area, can offer a more sustainable, cost-effective, and versatile alternative for a range of industrial, environmental, and medical applications.
Oil palm empty fruit bunch (OPEFB) is one of the potential feedstocks for production of bioethanol. Among the challenges in the conversion of lignocellulosic material to bioethanol is pretreatment. This study aims to determine the optimum conditions of OPEFB pretreatment by using microwaves and aluminum salt catalysts, i.e., AlK(SO4)(2) and Al-2(SO4)(3), for the production of reducing sugars that could be further fermented to bioethanol. The addition of inorganic salts, such as aluminum salt catalysts, during microwave heating enables to improve the results of biomass pretreatment. The optimization was conducted using the one factor at a time (OFAT) method. In Step 1, the factor optimized was the temperature (180-200 degrees C), while in Step 2 and Step 3 the factors optimized were the heating time (2-10 min), and the amount of catalysts (100-400 mu mol/g biomass). The effects of the pretreatment could be seen clearly by the RSY obtained after enzymatic saccharification, based on the weight of pretreated OPEFB, with higher results on the OPEFB pretreated with microwave and AlK(SO4)(2) or Al-2(SO4)(3) catalysts (55.08 or 55.75\%, respectively) than those without the catalysts (38.32 or 38.36\%, respectively). The total reducing sugar yield (RSY) from pretreatment hydrolysate and enzymatic saccharification was determined and used as a parameter in the optimization. The characteristics of pretreated OPEFB at optimum conditions were also compared with those of untreated OPEFB. Optimum conditions of OPEFB pretreatment by microwave heating with AlK(SO4) 2 catalyst were 200 degrees C, 6 min, with 300 mu mol catalyst/g biomass, whereas those with Al-2(SO4)(3) catalyst were 180 degrees C, 6 min, with 200 mu mol catalyst/g biomass. At these conditions, the RSY reached 61.7 and 58.1\% based on the initial biomass, respectively.
Fusarium oxysporum is among the few filamentous fungi capable of fermenting ethanol directly from lignocellulose biomass (LCB). It has the essential enzymatic toolbox to disintegrate LCB to its monosaccharides, which subsequently fermented to ethanol under anaerobic and micro-aerobic conditions. However, the structural complexity of LCB and modest performances of wild fungi are major limitations for application in local biorefineries. This study assessed the potential of the locally isolated Fusarium oxysporum for the production of bioethanol from Ficus fruits (Ficus cunia) using Consolidated Bioprocessing (CBP). The maximum ethanol concentration achieved was at 5\% substrate loadings with pH 6 irrespective of temperature variance, attaining a concentration of 3.54 g/L and 3.88 g/L at 28 degrees C and 32 degrees C, respectively. The monitoring of analytes (glucose, arabinose, cellobiose, xylose, acetic acid, ethanol, furfural, and HMF) in this study suggests the utilization of an array of sugars released from Ficus fruits, irrespective of the difference in the process parameters. This study also shows that CBP of freshly grounded Ficus fruits was feasible employing a mild hydrothermal pretreatment (autoclaved at 121 degrees C for 30 min in 1:10 w/v) and without supplementing any extraneous enzymes.
Enzymatic hydrolysis was proposed for the first time to purify the sub-fraction of water-extracted cassia polysaccharide (CP-40), and a homogeneous polysaccharide CP-40-M was obtained with relatively high yield. The structural features of CP-40-M were characterized using size-exclusion chromatography equipped with multiple detectors (SEC-MALLS), high-performance anion-exchange chromatography (HPAEC), methylation and gas chromatography-mass (GC-MS), as well as nuclear magnetic resonance (NMR) spectra. The weight-average molecular weight for CP-40-M was determined to be 0.29 x 10(5) Da, and the molar ratio of xylose to glucuronic acid was 4.62. The structure of CP-40-M was elucidated to be glucuronoxylan, with glucopyranosyluronic acid group terminally attached to O-2 of the -> 4)-beta-Xylp-(1 -> backbone. It was the first time to obtain this type of xylan from the water extract of Cassia obtusifolia seeds. The structure elucidation of CP-40-M was meaningful for better understanding the natural characteristics of cassia polysaccharide and important for their potential use in food industry and folk medicine. (C) 2017 Published by Elsevier B.V.
This work highlights that bio-based chemicals may not automatically be synonymous with ``green{''
Bioprospecting genes and proteins related to plant biomass degradation is an attractive approach for the identification of target genes for biotechnological purposes, especially those with potential applications in the biorefinery industry that can enhance second-generation ethanol production technology. Trichoderma harzianum is a potential candidate for cellulolytic enzyme prospection and production. Herein, the enzymatic activities, transcriptome, exoproteome, and coexpression networks of the T. harzianum strain CBMAI-0179 were examined under biomass degradation conditions. We identified differentially expressed genes (DEGs) and carbohydrateactive enzyme (CAZyme) genes related to plant biomass degradation and compared them with those of strains from congeneric species (T. harzianum IOC-3844 and T. atroviride CBMAI-0020). T. harzianum CBMAI-0179 harbors strain- and treatment-specific CAZyme genes and transcription factors. We detected important proteins related to biomass degradation, including 13-glucosidases, endoglucanases, cellobiohydrolases, lytic polysaccharide monooxygenases, endo-1,4-13-xylanases and 13-mannanases. Based on coexpression networks, an enriched cluster with degradative enzymes was described, and the subnetwork of CAZymes revealed strong correlations among important secreted proteins and differentially expressed CAZyme genes. Our results provide valuable information for future studies on the genetic regulation of plant cell wall-degrading enzymes. This knowledge can be exploited for the improvement of enzymatic reactions in biomass degradation for bioethanol production.
Leaching of soluble elements from cultivated soils is a major concern to meet the target of agricultural sustainability in most areas. The effect of biochar application to a cultivated soil on water drainage and the consequent solute losses was assessed during a trial carried out over two consecutive growing seasons. Biochar was added to a loam-texture soil, at 0, 1, and 2\% d.w. rates. A lysimeter-like set-up arranged in the experimental field-unit, allowed collecting the percolating water. Two multiple linear regressions (ANCOVA models) were applied to detect biochar effect on: (1) The seasonal amount of drained water; and (2) the concentration of solutes in the drained water. The statistical comparison among a set of slope coefficients as affected by treatments (growing season and biochar) was used as modelling approach. The lower biochar application rate (1\%) significantly reduced both the amount of drained water and its concentration in solutes. Conversely, the higher biochar application rate (2\%) showed no significant effects. Nitrate and chloride showed a significant interaction with biochar application rates. Higher biochar application increased nitrate leaching while reduced that of chloride. Biochar application within a rate no more than 1\% resulted in a useful and quite effective technical operation.
In the last decade, adsorption has been used to minimize the pollution caused by dyes, which represents a serious environmental problem. In this context, this work reports the preparation of phthalic anhydride-modified cellulose (PhCel), through the reaction of cellulose (Cel) with phthalic anhydride (Ph). The efficiency of the reaction was observed by elemental analysis, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetry/derivative thermogravimetry (TG/DTG). The adsorbent matrix (Cel and PhCel) was used in the removal of crystal violet (CV) and methylene blue (MB) dyes in aqueous medium. In the kinetic study, the experimental data obtained had the best fit to the pseudo-first-order model. In general, the isotherms obtained at different temperatures had a best fit to the model proposed by Langmuir, and the CV and MB adsorption process in adsorbent matrixes can be favored strictly by hydrogen bonds and/or electrostatic interactions for Cel and electrostatic interactions for PhCel.
A rapid and effective dissolution and activation of cellulose was demonstrated by a reversible reaction of CO2 with the hydroxyl groups of the cellulose backbone in the presence of 1,8-diazabicyclo{[
A new carboxylic bio-resin was synthesized from raw arecanut husk through mercerization and ethylenediaminetetraacetic dianhydride (EDTAD) carboxylation. The synthesized bio-resin was characterized using thermogravimetric analysis, field emission scanning electron microscopy, proximate \& ultimate analyses, mass percent gain/loss, potentiometric titrations, and Fourier transform infrared spectroscopy. Mercerization extracted lignin from the vesicles on the husk and EDTAD was ridged in to, through an acylation reaction in dimethylformamide media. The reaction induced carboxylic groups as high as 0.735 mM/g and a cation exchange capacity of 2.01 meq/g functionalized mercerized husk (FMH). Potentiometric titration data were fitted to a newly developed single-site proton adsorption model (PAM) that gave pKa of 3.29 and carboxylic groups concentration of 0.741 mM/g. FMH showed 99\% efficiency in Pb(II) removal from synthetic wastewater (initial concentration 0.157 mM), for which the Pb(II) binding constant was 1.73 x 10(3) L/mol as estimated from modified PAM. The exhaustion capacity was estimated to be 18.7 mg/g of FMH. Desorption efficiency of Pb(II) from exhausted FMH was found to be about 97\% with 0.1 N HCl. The FMH simultaneously removed lead and cadmium below detection limit from a real lead acid battery wastewater along with the removal of Fe, Mg, Ni, and Co. (C) 2017 Elsevier B.V. All rights reserved.
Two grams of delignified substrate at 10\% (w/v) level was subjected to biphasic dilute acid hydrolysis using phosphoric acid, hydrochloric acid and sulfuric acid separately at 110 degrees C for 10 min in phase-I and 121 degrees C for 15 min in phase-II. Combinations of acid concentrations in two phases were varied for maximum holocellulose hydrolysis with release of fewer inhibitors, to select the suitable acid and its concentration. Among three acids, sulfuric acid in combination of 1 \& 2\% (v/v) hydrolyzed maximum holocellulose of 25.44 +/- 0.44\% releasing 0.51 +/- 0.02 g/L of phenolics and 0.12 +/- 0.002 g/L of furans, respectively. Further, hydrolysis of delignified substrate using selected acid by varying reaction time and temperature hydrolyzed 55.58 +/- 1.78\% of holocellulose releasing 2.11 +/- 0.07 g/L and 1.37 +/- 0.03 g/L of phenolics and furans, respectively at conditions of 110 degrees C for 45 min in phase-I \& 121 degrees C for 60 min in phase-II. (C) 2015 Elsevier Ltd. All rights reserved.
Nitrates are present in drinking water sources and pose serious health issues in many countries throughout the world. In this research, nitrate removal by palm kernel shell-based lignocellulose anion resins was studied under various nitrate concentrations, pH, and adsorbent dosages. The nitrate adsorption capacity demonstrated by the biomaterial-based resins was 53.18 mg/L. A pseudo-second order model and the Weber-Morris diffusion model were used to assess the adsorption process. The thermodynamic study predicted the exothermic nature of the process and the dominance of physical adsorption. Resins were characterized using elemental, proximate, and chemical analyses as well as by the pH at the point of zero charge. The lignocellulose-based adsorbent is a satisfactory material for nitrate removal from water and can be regenerated and reused.
Pretreatment of rice husk by alkaline peroxide assisted wet air oxidation (APAWAO) approach was investigated with the aim to enhance the enzymatic convertibility of cellulose in pretreated rice husk. Rice husk was presoaked overnight in 1\% (w/v) H2O2 solution (pH adjusted to 11.5 using NaOH) (equivalent to 16.67 g H2O2 and 3.63 g NaOH per 100 g dry, untreated rice husk) at room temperature, followed by wet air oxidation (WAO). APAWAO pretreatment resulted in solubilization of 67 wt \% of hemicellulose and 88 wt \% of lignin initially present in raw rice husk. Some amount of oligomeric glucose (8.3 g/L) was also observed in the APAWAO liquid fraction. APAWAO pretreatment resulted in 13-fold increase in the amount of glucose that could be obtained from otherwise untreated rice husk. Up to 86 wt \% of cellulose in the pretreated rice husk (solid fraction) could be converted into glucose within 24 hours, yielding over 21 g glucose per 100 g original rice husk. Scanning electron microscopy was performed to visualize changes in biomass structure following the APAWAO pretreatment. Enzymatic cellulose convertibility of the pretreated slurry at high dry matter loadings was also investigated. (C) 2011 American Institute of Chemical Engineers Biotechnol. Prog., 27: 691-697, 2011
In view of the recent emphasis on non-conventional chemistry, application of ultrasound in isolation of plant polysaccharides represents a viable alternative to traditional extraction processes. This review presents an extensive literature survey of ultrasound-assisted extraction of polysaccharides from different plant materials, particularly herbal plants and secondary agricultural plant sources. Targeted, multistep methods were applied with respect to differences in the types of polysaccharides and their location in plant cell walls. The effectiveness of the methods was evaluated according to yield and properties of the isolated polysaccharides in comparison to classical extraction methods. Substantial shortening of extraction time, reduction of reagent consumption and/or extraction temperature are the most important advantages of the ultrasonic treatment. In combination with sequential extraction steps using different solvents, sonication was shown to be effective in separation and/or purification of polysaccharides. The disadvantages of the sonication treatment, such as degradation and compositional changes of the polysaccharide preparations are discussed as well.
This study evaluated the effect of temperature in the thermophilic range (45, 55, and 65 degrees C) for simultaneous production of hydrogen and ethanol in an anaerobic fluidized bed reactor (AFBR) using cassava wastewater as substrate, with a hydraulic retention time of 2 h. Substrate concentration varied from 4.5 to 5.5 g COD L-1. Maximum yields of hydrogen (1.98 mol-H-2 mol(-1)-glucose) and ethanol (2.06 mol-EtOH mol(-1)-glucose) were achieved at 55 degrees C. In this condition, the hydrogen production rate was 2.05 L h(-1) L-1, increased by 86\% regarding 45 oC. The concentration of organic acids reduced about 42\% with increasing temperature from 45 to 55 degrees C and diminished 37\% from 55 to 65 degrees C. Acetic acid prevailed over other metabolites in percentages about 41-51\%, followed by butyrate at 45 oC (33.8\%), and ethanol at 55 oC (25.5\%) and 65 oC (30.8\%). The ethanol concentration remained practically constant (4.00 +/- 1.51-4.74 +/- 1.44 mM) if considering the associated uncertainty range. Overall, thermophilic temperatures were favorable for biofuel production, however, it is suggested to study other HRT in future work to avoid overloading the system.
Feasibility of hydrochar and activated carbon production from brewed tea waste was investigated in this study. Brewed tea waste was hydrothermally carbonised in subcritical water to obtain hydrochar as energy feedstock. Hydrothermal carbonisation experiments were performed at different process temperatures to determine its effect on fuel properties and combustion behaviour of resultant hydrochar. Increasing the process temperature yielded less amount of hydrochar. Higher calorific value and lower burnout temperature was observed for hydrochar. Hydrothermal carbonisation could remove only 25\%-35\% of initial ash in biomass and could not remove CaO in brewed tea waste. Hence, hydrochar had high slagging risk during combustion, which was only slightly lower than that of feedstock. On the other hand, hydrochar had lower fouling risk due to removal of K2O. ZnCl2 activation of hydrochar produced an activated carbon with high surface area and acceptable porosity.
The densification of raw material into fuel briquettes is one of the routes to convert biomass into energy. This method provides uniformity to the solid fuel, better physical and energy properties, facilitating its storage and transport, in addition to more homogeneous combustion. Given the importance of these characteristics, this work presents a literature review, emphasizing the experimental levels of the variables of the briquetting process, as well as on the most relevant quality parameters for obtaining briquettes. We also carry out a survey of the main technologies used in the production of briquettes, as well as the experimental methodologies and statistical analysis used in the planning and validation of processes. It was observed among the studies that the raw material granulometry, followed by pressure, initial moisture, compaction time and binder are the most used process variables for the production of briquettes. Other factors, such as the proportion of biomass, process temperature and thermal pre-treatments are used to obtain greater energetic and physical responses. Among the works, divergences were observed regarding the relevance and interaction of some process variables on the quality variables of the briquettes, indicating the need for the experiments to be mathematically modeled.
Xylitol production from lignocellulose-hydrolyzed glucose and xylose is a sustainable and environment-friendly process. In this study, Kluyveromyces marxianus YZB194, constructed by overexpressing ScGAL2(N376F) from Saccharomyces cerevisiae and NcXYL1 from Neurospora crassa, and deleting GPDI, KU70, PGI1, and XYL2, was used for xylitol production by co-utilizing glucose and xylose. By deleting PGI1, the glucose repression effect on xylose in K. marxianus was released, besides, glucose metabolism in YZB194 was refactored through the pentose phosphate pathway, a pathway yielding the largest supply of NADPH in yeast. The metabolic pathway of xylitol was blocked by deleting of XYL2. By simultaneously co-utilizing 70 g/L glucose and 140 g/L xylose, 139.96 g/L xylitol with a productivity of 0.83 g/L/h was obtained by YZB194 at 37 degrees C under aerobic conditions. Through fed-batch fermentation in a fermenter at 42 degrees C, 203.57 g/L xylitol with a productivity of 2.99 g/L/h and yield on xylose of 0.99 g/g were obtained using K. marxianus YZB194. A platform for xylitol production by co-utilizing glucose and xylose via rewriting the glucose metabolism pathway was implemented.
Herein, we report the secretome of Penicillium chrysogenum P33 under induction of lignocellulose for the first time. A total of 356 proteins were identified, including complete cellulases and numerous hemicellulases. Supplementing a commercial cellulase with increasing dosage of P33 enzyme cocktail from 1 to 5 mg/g substrate increased the release of reducing sugars from delignified corn stover by 21.4\% to 106.8\%. When 50\% cellulase was replaced by P33 enzyme cocktail, release of reducing sugars was 78.6\% higher than with cellulase alone. Meanwhile, glucan and xylan conversion was increased by 37\% and 106\%, respectively. P33 enzyme cocktail also enhanced commercial cellulase hydrolysis against four different delignified lignocellulosic biomass. These findings demonstrate that mixing appropriate amount of P33 cocktail with cellulase improves polysaccharide hydrolysis, suggesting P33 enzymes have great potential for industrial applications.
The primary objective of this work was to evaluate a chemically modified cellulose for the sorption efficiency and selectivity to remove cadmium from spiked high-hardness groundwater. Heterogeneous esterification of cellulose with succinic anhydride in toluene under basic conditions has proceeded very efficiently to yield the succinylated cellulose (SC) with fairly high DS value, as confirmed by FTIR and solid-state MAS C-13 NMR spectroscopies. Deprotonation of the free carboxylic acid group was achieved by alkaline treatment of SC with saturated NaHCO3 aqueous solution. Batch experiments were carried out on the resulting sodic material (NaSC) to examine its cadmium-removing capability in both distilled water (DW) and spiked groundwater (GW). The results obtained from the sorption characteristics (kinetics, isotherms and pH effect) have revealed that NaSC material is particularly effective in removing cadmium from both DW and GW solutions, with a maximum uptake of 185.2 and 178.6 mg g(-1), respectively. These comparable sorption capacities strongly suggest that NaSC sorbent is highly selective to heavy metal over alkaline earth cations (Ca2+ and Mg2+) and therefore less susceptible to interference from background ions, naturally present in groundwater. On the other hand, cadmium sorption is shown to decrease with a decrease in pH which is indubitably inherent to the competing proton during the ion-exchange process. Furthermore, the material has proven to be efficiently regenerable by using a NaCl brine solution. Thus, the use of the sorbent sequentially to the first regeneration led to nearly no attenuation in the material's capacity for cadmium-removal. Finally, the sorption effectiveness of NaSC is compared to those of other low-cost sorbents so far reported in the literature. (C) 2009 Elsevier B.V. All rights reserved.
In Brazil, the production and consumption of palm heart, especially from the Bactris gasipaes Kunth, generates a large number of lignocellulosic by-products. This study reports the obtainment of xylooligosaccharides (XOS) from xylans extracted from these residues. Xylans from peach palm waste (inner sheath and peel) were extracted using a mild alkali treatment with recovery yields of 82\% and 80\%, respectively. XOS were obtained through enzymatic hydrolysis employing a commercial xylanase with yields from xylan inner sheath and xylan peel of 50.1\% and 48.8\%, respectively. The antioxidant potential of XOS was measured employing five of the most commonly used procedures. In overall terms, the XOS from the xylans of peach palm wastes showed higher antioxidant capacity than the XOS obtained from the commercial xylans. The chemical structures of the XOS were determined by mass spectrometry (ESI-MS). The ESI-MS spectra suggest that XOS with grouped xylose or arabinose units ranging from 2 to 5 (differing by 132 Da) and as sodium adduct ions {[
Proper modulation of the compositions and porosities of carbon materials is crucial for capacitive energy storage and gas adsorption of carbon materials. Herein, porous N-doped carbon was synthesized from formamide by using a sequential hydrothermal treatment followed by pyrolysis with KOH. The activation with KOH resulted in a high increase in the porosity of the carbon and in the performance. A high porosity of >3000 m(2) g(-1) was achieved with a low KOH/C ratio of only 2. The presence of nitrogen introduces pseudocapacitance and also enhances the electron density in the carbon framework. The obtained N-doped porous carbon exhibits a good specific capacitance value of 307 F g(-1) at 1 A g(-1) in 6 M KOH. Also, the fabricated symmetric supercapacitor displays excellent performance in both alkaline and neutral media. It shows a stable cycling performance (91.4\% retention after 10 000 cycles), a reasonable rate performance, and a maximum energy density of 14.36 Wh kg(-1) at a power density of 351 W kg(-1) in 1 M Na2SO4. The prepared material shows good gas adsorption behavior, and as a H-2 adsorbent at 77 K, it shows a good uptake value of 2.86 wt \% at 1 bar pressure. It also shows maximum CO2 uptake values of 4.88 and 2.88 mmol g(-1) at 1 bar pressure under temperatures of 0 and 25 degrees C, respectively, with a high CO2/N-2 selectivity of 14.54. The compound also shows a methane uptake capacity of 1.67 mmol g(-1) at 0 degrees C and 1 bar pressure with a CO2/CH4 selectivity of 3.8. Our research provides a promising material for both energy storage and gas storage through a green synthetic strategy.
Acetic acid (AA) and formic acid (FA) are two of the major fermentation inhibitors found in hemicellulosic hydrolysates. Their removal, which is necessary for the use of hydrolysates as fermentation substrates, can be achieved by adsorption on hydrotalcites. This study aimed to assess the efficiency of hydrotalcites in removing AA and FA from aqueous solution. Kinetic, thermodynamic, and equilibrium experiments were conducted using hydrotalcites composed of 30, 63, or 70\% MgO. Calcined hydrotalcites composed of 70 and 63\% MgO (MG70c and MG63c) had the best kinetic performance, removing 97\% of FA and 91\% of AA. The adsorption process followed pseudo-first-order kinetics. The Boyd model showed that external mass transfer or a combination of intraparticle diffusion and external mass transfer controls the process. Adsorption equilibrium was evaluated at different temperatures (30, 40, 50, and 60 degrees C) using MG70c as an adsorbent. The Freundlich model provided the best fit to adsorption isotherms. Thermodynamic studies indicated that adsorption was spontaneous and endothermic in nature. The results confirmed the efficiency of MG70c in removing AA and FA from aqueous solution.
Simultaneous steam explosion and alkaline depolymerization was studied to develop an economic and green process for alkaline pretreatment of lignocellulose. Steam explosion facilitated alkaline delignification and decreased the amount of alkali used during pretreatment. Different amounts of lignin and hemicellulose were removed within 5 min by using different sodium hydroxide concentrations and steam explosion severity. The main component of lignin collected using our simultaneous process was acid-insoluble lignin, reaching a purity of 84 \%. Structural analysis indicated that steam explosion and sodium hydroxide had a synergistic effect on the removal of lignin and hemicellulose from corncob. The effect to four simultaneous pretreatment process of delignification transformed cellulose I to cellulose II, enhancing the enzymatic conversion of cellulose to glucose from 22 \% to 96 \%. The process of simultaneous steam explosion and alkaline depolymerization shows a potential for application in the lignocellulose biorefinery.
This review compiles a comparative study of agricultural byproducts efficacy for wastewater purification using functionalized adsorbents for Pb(II) ions. We have compiled enormous data based on selective affinity toward Pb(II) ions. The experimental factors like pH, amount of adsorbent, time of contact, temperature, and initial concentration of ions affecting the adsorption of Pb(II) ions have also been explored. Besides, the various other adsorption kinetics and models of adsorption isotherms are discussed. Future directions of research and development of adsorptive Pb(II) ions removal from industrial wastewater are proposed.
Studies on bioethanol produced from a variety of non-edible feedstocks have recently gained considerable attention because such production can avoid the conflict between food and fuel. In this study, an attempt was made to investigate the production of bioethanol using low-cost feedstock, namely, seaweed solid wastes obtained after the extraction of x-carrageenan. The utilisation of seaweed solid wastes will simultaneously help to overcome its disposal problem. Two different processes were used: the SHF (separate hydrolysis and fermentation) process and the SSF (simultaneous saccharification and fermentation) process. For the SHF process, enzymatic hydrolysis was conducted by varying three process variables, substrate concentration, pH and temperature, but a constant enzyme dosage was maintained. The highest glucose yield of 99.8\% was obtained at pH 4.8, a temperature of 50 degrees C and a substrate concentration of 2\% (w/v) seaweed solid wastes. With subsequent fermentation, a bioethanol yield of 55.9\% was obtained. In contrast, for the SSF process, a yield of 90.9\% bioethanol was obtained. From these results, it was determined that the SSF of seaweed solid wastes with Saccharomyces cerevisiae has several advantages over SHF because the former is a simple one-step procedure that can save time, cost and energy consumption while achieving a high yield of bioethanol. (C) 2014 Elsevier Ltd. All rights reserved.
This report demonstrates the fastest technique to successfully achieve carboxymethyl cellulose (CMC) from office paper waste, within 30 min at ambient temperature using ultrasonic-assisted method as a source of energy. The obtained CMC was characterized using FTIR, TGA, and NMR techniques to confirm its structure. The FTIR spectrum showed characteristic peaks of carboxymethyl groups and its salt at the wavenumbers of 1585 (C=O) and 1412 (C-O) cm(-1). The TGA results of CMC exhibited the loss of carbon dioxide at ca. 260 - 300 degrees C. Moreover, a higher ash yield of the obtained CMC indicated the substitution of carboxymethyl in the structure. The CMC product structure was confirmed using C-13- and HMBC 2D-NMR. The HMBC 2D-NMR results indicated a correlation between carbonyl and methylene carbons of carboxymethyl groups and protons of pyranose ring, implying that pyranose ring was substituted successfully by monocholoroacetic acid (MCA). The optimal conditions were obtained by using 4.11 ml of 30\%w/v NaOH and 1.4 g of MCA in 40 ml of isopropanol at ambient temperature. The resulting CMC showed 0.75 degree of substitution at 18.75 W/ml ultrasonic intensity. (C) 2020 Elsevier Ltd. All rights reserved.
This paper reviews the serviceability of hydrous ethanol as a clean, cheap and green renewable substitute fuel for spark ignition engines and discusses the comparative chemical and physical properties of hydrous ethanol and gasoline fuels. The significant differences in the properties of hydrous ethanol and gasoline fuels are sufficient to create a significant change during the combustion phase of engine operation and consequently affect the performance of spark-ignition (SI) engines. The stability of ethanol-gasoline-water blends is also discussed. Furthermore, the effects of hydrous ethanol, and its blends with gasoline fuel on SI engine combustion characteristics, cycle-to-cycle variations, engine performance parameters, and emission characteristics have been highlighted. Higher water solubility in ethanol-gasoline blends may be obviously useful and suitable; nevertheless, the continuous ability of water to remain soluble in the blend is significantly affected by temperature. Nearly all published engine experimental results showed a significant improvement in combustion characteristics and enhanced engine performance for the use of hydrous ethanol as fuel. Moreover, carbon monoxide and oxides of nitrogen emissions were also significantly decreased. It is also worth pointing out that unburned hydrocarbon and carbon dioxide emissions were also reduced for the use of hydrous ethanol. However, unregulated emissions such as acetaldehyde and formaldehyde were significantly increased.
Hydrogels are an attractive system for a myriad of applications. While most hydrogels are usually formed from synthetic materials, lignocellulosic biomass appears as a sustainable alternative for hydrogel development. The valorization of biomass, especially the non-woody biomass to meet the growing demand of the substitution of synthetics and to leverage its benefits for cellulose hydrogel fabrication is attractive. This review aims to present an overview of advances in hydrogel development from non-woody biomass, especially using native cellulose. The review will cover the overall process from cellulose depolymerization, dissolution to crosslinking reaction and the related mechanisms where known. Hydrogel design is heavily affected by the cellulose solubility, crosslinking method and the related processing conditions apart from biomass type and cellulose purity. Hence, the important parameters for rational designs of hydrogels with desired properties, particularly porosity, transparency and swelling characteristics will be discussed. Current challenges and future perspectives will also be highlighted.
Pretreatment is an essential prerequisite to overcome recalcitrance of biomass and enhance the ethanol conversion efficiency of polysaccharides. Compared with other pretreatment methods, liquid hot water (LHW) pretreatment not only reduces the downstream pressure by making cellulose more accessible to the enzymes but minimizes the formation of degradation products that inhibit the growth of fermentative microorganisms. Herein, this review summarized the improved LHW process for different biomass feedstocks, the decomposition behavior of biomass in the LHW process, the enzymatic hydrolysis of LHW-treated substrates, and production of high value-added products and ethanol. Moreover, a combined process producing ethanol and high value-added products was proposed basing on the works of Guangzhou Institute of Energy Conversion to make LHW pretreatment acceptable in the biorefinery of cellulosic ethanol. (C) 2015 Elsevier Ltd. All rights reserved.
Penicillium oxalicum can secrete numerous of plant biomass-degrading enzymes, but limited information is available regarding the mechanisms associated with their secretion. In the Golgi-to-vacuole pathway, the type I transmembrane receptor Vps10p is involved in the sorting of the soluble vacuolar proteins and can also target recombinant and aberrant proteins from the Golgi to the vacuole for degradation. Here, we used the combination of phenotypic characterization and comparative secretome analysis to explore the effect of disruption of the vps10 gene in P. oxalicum (Poxvps10) on endogenous cellulolytic enzyme secretion. The study found that PoxVps10p is required for the targeting and delivery of vacuolar PoxCpyA to the vacuole in P. oxalicum. Poxvps10p deletion enhances extracellular protein and cellulase production by P. oxalicum when the cells are grown on a cellulosic substrate (wheat bran and Avicel). Furthermore, secretome analysis revealed higher relative amount of cellulases, lytic polysaccharide monooxygenase and post-translational modification-related proteins in the \& UDelta;Poxvps10 mutant than in the wild-type (WT) strain, which may explain the higher cellulase production by the \& UDelta;Poxvps10 than the WT strain. This study thus provides a new target for manipulating the secretory pathway to enhance the cellulolytic enzyme production.
Extremely acidic conditions (pH < 1.0) during hydrogen sulfide (H2S) biotreatment significantly reduce the cost of pH regulation; however, there remain challenges to its applications. The present study investigated the H2S removal and biomass variations in biotrickling filter (BTF) under long-term highly acidic conditions. A BTF operated for 144 days at pH 0.5-1.0 achieved an H2S elimination capacity (EC) of 109.9 g/(m(3).h) (removal efficiency = 97.0\%) at an empty bed retention time of 20 s, with an average biomass concentration at 20.6 g/LBTF. The biomass concentration at neutral pH increased from 22.3 to 49.5 g/L-BTF within 28 days. In this case, elemental sulfur (S-0) accumulated due to insufficient oxygen transfer in biofilm, which aggravated the BTF blockage problem. After long-term domestication under extremely acidic conditions, a mixotrophic acidophilic sulfur-oxidizing bacteria (SOB) Alicyclobacillus (abundance 55.4\%) were enriched in the extremely acidic biofilm, while non-aciduric bacteria were eliminated, which maintained the balance of biofilm thickness. Biofilm with optimum thickness ensured oxygen transfer and H2S oxidation, avoiding the accumulation of S-0. The BTF performance improved due to the enrichment of active mixotrophic SOB with high abundance under extremely acidic conditions. The mixotrophic SOB is expected to be further enriched under extremely acidic conditions by adding carbohydrates to enhance H2S removal.
Fractionation of lignocellulosic is a fundamental step in the production of value-added biobased products. This work proposes an initiative to efficiently extract lignin from the corn stover using a single-step solvothermal fractionation in the presence of an acid promoter (H2SO4). The organic solvent mixture used consists of ethyl acetate, ethanol, and water at a ratio of 30: 25:45 (v/v), respectively. H2SO4 was utilized as a promoter to improve the performance and selectivity of lignin removal from the solid phase and to increase the amount of recovered lignin in the organic phase. The optimal conditions for this extraction, based on response surface methodology (RSM), are a temperature of 180 degrees C maintained for 49.1 min at an H2SO4 concentration of 0.08 M. The optimal conditions show an efficient reaction with 98.0\% cellulose yield and 75.0\% lignin removal corresponding to 72.9\% lignin recovery. In addition, the extracted lignin fractions, chemical composition, and structural features were investigated using Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, and two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance spectroscopy (2D-HSQC NMR). The results indicate that the recovered lignin primarily contains a beta-O-4 linking motif based on 2D-HSQC spectra. In addition, new C-C inter-unit linkages (i.e., beta-beta, and beta-5) are not formed in the recovered lignin during H2SO4-catalyzed solvothermal pretreatment. This work facilitates effective valorization of lignin into value-added chemicals and fuels.
Biofuel is one of the promising alternatives for petroleum-based fuels and the bioethanol produced from agricultural residues/industrial wastes are a viable alternative, and current trend in research. In this context, this work reports the utilisation of the waste potatoes (Solanum tuberosum L.) from food industries as precursors for bioethanol. Waste potato mass (WPM) was pre-treated using ultrasonication and hydrolysed using either hydrochloric acid (US-HCl) or alpha-amylase (US-Enzyme). The process conditions such as initial S. cerevisiae concentration (10-20 g/L), enzyme concentration (10-30 U/mL), HCl concentration (1-3\% v/v) and ultra-sonication time (5-15 min) were modelled using Box-Behnken RSM design and artificial neural networks (ANN). ANN modelled the experimental data better than RSM which was evident from different errors. Optimum parameters were evaluated using genetic algorithm. The optimal parameters predicted for US-HC1 hydrolysis was 65.8 mg/L at HCl concentration 2.1\%, ultra-sonication time 10.7 min, and S. cerevisiae concentration 19.2 g/L with R-2 0.979, whereas, for US-Enzyme hydrolysis was 54.1 g/L at alpha-amylase concentration 25.3 U/mL, ultrasonication time 10.2 min, and S. cerevisiae concentration 19.2 g/L with R-2 0.959. Hence, ultrasonic pretreatment increases the bioethanol yield from waste potatoes and US-HCl process was efficient than the US-Enzyme process.
In this study, the Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to determine the optimization of bio-char production from chicken manure wastes. The effects of temperature, heating rate and reaction time on pyrolysis of chicken manure waste were investigated in the fluidized bed reactor. Operation conditions were selected between the reaction temperatures was 200-500 degrees C, the heating rate was 5-20 degrees C/min and the reaction time was 30-120 min. The optimum condition was determined using the surface area results of the bio-chars. As a result of the optimization studies, it was determined that the temperature should be 400 degrees C, the heating rate should be 5 degrees C/min and the reaction time should be 110 min in order to obtain bio-char with highest surface area. Bio-char obtained in optimum condition in fluidized bed reactor was subjected to chemical activation with KOH and HCl, respectively. The CO2 adsorption capacity of raw and activated bio-char products was determined as 48.7, 76.8 and 85.7 mg/g at 25 degrees C using thermogravimetric analysis method, respectively. As a result, it has been found that the activated bio-chars are effective adsorbents for CO2 storage and it has been demonstrated that it is possible to evaluate chicken manure wastes for removing environmental pollutant in an economical way. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
This paper compares conventional and microwave hydrothermal carbonization (HTC) of human biowaste (HBW) at 160 degrees C, 180 degrees C and 200 degrees C as a potential technology to recover valuable carbonaceous solid fuel char and organic-rich liquor. Also discussed are the influence of HTC heating methods and temperature on HBW processing conversion into solid fuel char, i.e. yield and post-HTC management, dewaterability rates, particle size distribution and the carbon and energy properties of solid fuel char. While HTC temperatures influenced all parameters investigated, especially yield and properties of end products recovered, heating source effects were noticeable on dewatering rates, char particle sizes and HBW processing/end product recovery rate and, by extension, energy consumed. The microwave process was found to be more efficient for dewatering processed HBW and for char recovery, consuming half the energy used by the conventional HTC method despite the similarity in yields, carbon and energy properties of the recovered char. However, both processes reliably overcame the heterogeneity of HBW, converting them into non-foul end products, which were easily dewatered at <3 seconds/g total solids (TS) (c.f. 50.3 seconds/g TS for a raw sample) to recover energy-densified chars of approximate to 17 MJ/kg calorific value and up to 1.4 g/l of ammonia concentration in recovered liquor.
Nanocrystalline cellulose (NCC) was extracted from microcrystalline cellulose via low-intensity ultrasonic-assisted sulfuric acid hydrolysis process. NCC samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size distribution (PSD) analysis, Fourier-transformed infrared spectra (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and rheological measurement. It was found that NCC yield reached 40.4 \% under the optimum process of low-intensity ultrasonic-assisted sulfuric acid hydrolysis, while it was only 33.0 \% in the absence of ultrasonic treatment. Furthermore, the results showed that the two NCC samples obtained from ultrasonic-assisted hydrolysis and conventional hydrolysis were very similar in morphology, both exhibiting rod-like structures with widths and lengths of 10-20 and 50-150 nm, respectively. XRD result revealed that the NCC sample from ultrasonic-assisted hydrolysis contained a small amount of cellulose II and possessed a Segal Crystallinity Index of 90.38 \% and a crystallite size of 58.99 a{''
BackgroundThe forest biorefinery plays an important part in the evolving circular bioeconomy due to its capacity to produce a portfolio of bio-based and sustainable fuels, chemicals, and materials. To tap into its true potential, more efficient and environmentally benign methods are needed to fractionate woody biomass into its main components (cellulose, hemicellulose, and lignin) without reducing their potential for valorization. This work presents a sequential fractionation method for hardwood based on steam pretreatment (STEX) and hydrotropic extraction (HEX) with sodium xylene sulfonate. By prehydrolyzing the hemicellulose (STEX) and subsequently extract the lignin from the cellulose fraction (HEX), the major wood components can be recovered in separate process streams and be further valorized.ResultsUsing autocatalyzed STEX and HEX, hemicellulose (>70\%) and lignin (similar to 50\%) were successfully fractionated and recovered in separate liquid streams and cellulose preserved (99\%) and enriched (similar to twofold) in the retained solids. Investigation of pretreatment conditions during HEX showed only incremental effects of temperature (150-190 degrees C) and hold-up time (2-8h) variations on the fractionation efficiency. The hydrolyzability of the cellulose-rich solids was analyzed and showed higher cellulose conversion when treated with the combined process (47\%) than with HEX alone (29\%), but was inferior to STEX alone (75\%). Protein adsorption and surface structure analysis suggested decreased accessibility due to the collapse of the fibrillose cellulose structure and an increasingly hydrophobic lignin as potential reasons.ConclusionThis work shows the potential of sequential STEX and HEX to fractionate and isolate cellulose, hemicellulose, and a sulfur-free lignin in separate product streams, in an efficient, sustainable, and scalable process.
Lignocellulosics pretreatment is intended to dismantle biomass' natural recalcitrance. Chemical and morphological changes of lignocellulosic materials would occur through varying pretreatment processes. In order to figure out why the acid-pretreated and Kraft-cooked bamboo residues showed very different enzymatic digestibility, the surface properties of pretreated bamboo residues were characterized in this work. It was found that analyzed surface properties were considered to be associating with each corresponding enzymatic digestibility of the pretreated samples. The zeta potentials of pretreated bamboo residues have a negative correlation with enzymatic efficiency. Kraft-cooked substrates were found to posse a less hydrophobic nature and demonstrated higher enzymatic conversion than substrates that were dilute sulfuric acid pretreated. The surface accessibility analysis (BET and Direct Red staining) revealed that the higher enzymatic efficiency of Kraft-cooked materials was mostly due to the larger cellulosic surface area than that in acid-pretreated materials. The results re-affirm that different pretreatments create a variety of surface characteristics, leading to the idea that pretreatment and enzymatic hydrolysis can be favorably turned to maximize carbohydrate recovery from bamboo residues.
With the gradual increase in algal waste, its disposal has become a key problem in the field of marine environmental protection. Anaerobic digestion (AD) of algal biomass is one potential method for its treatment in a beneficial manner. However, AD of algae is hindered because of strong resilient cell walls, and hence, pretreatment of algae biomass before AD is an essential process. In this study, green algae (Enteromorpha) were used as the research substrate to explore the damage and impact of NaOH-urea pretreatment on biomass. Scanning electron microscopy and thermogravimetric analysis were used to analyze the damage of the cell wall structure of Enteromorpha via NaOH-urea pretreatment. The response surface method (RSM) was used for the optimization of pretreatment conditions to obtain the best experimental conditions. The experimental independent variables were pretreatment time, pretreatment temperature, and NaOH-urea concentration. RSM results showed that the optimal conditions are pretreatment time of 50 min, NaOH-urea concentration of 5.89\%, and pretreatment temperature of -16 degrees C. AD was carried out under these conditions. The results showed that cumulative gas production for the control group was 231.5 ml whereas the biogas yield for best optimal conditions was 521.5 and 413 ml, respectively. In addition, AD reaction kinetics was evaluated by two mathematical kinetic models. It was found that modified Gompertz model is more suitable for describing the AD behavior.
This study focused on the applying endo-xylanases to reduce the use of bleaching agent, coupled with the production of xylooligosaccharides (XOs), in mulberry paper making. Paper mulberry pulp (PMP) was consecutively prepared from paper mulberry bark by traditional NaOH-treatment, and two types of thermostable endo-xylanase from Streptomyces thermovulgaris TISTR1948 (wild-type and recombinant endo-xylanases) were employed in the biobleaching of PMP. This process was optimized to achieve maximum XOs yields and the highest PMP quality. The optimal condition was an enzyme dosage of 125 U/g PMP at 12 h of reaction time, both in a 500 mL laboratory bottle and a 150 L reactor. The mixture obtained from the reactor was separated as liquid of XOs derived from PMP (PMP-XOs) and solid biobleached PMP. The PMP-XOs from wild-type endo-xylanase were composed of 31.6\% xylopentaose (X5), 30.9\% xylohexaose and higher-degree XOs (X >= 6), and 11.7\% xylobiose (X2), whereas 76.6\% of X5 and 8.6\% of X2 were the main products from recombinant endo-xylanase. The PMP-XOs derived from both endo-xylanase types exhibited high antioxidant activities, reducing power, phenolic contents, and prebiotic efficacy. In addition, the application of both endo-xylanases enhanced the brightness of PMP by 5.1\% and 3.5\%, and reduced the kappa number by 9.1\% and 3.6\%, respectively. Biobleached PMP was subsequently subjected to the NaOCl bleaching step to produce the mulberry paper. This approach could reduce NaOCl consumption by 20-25\%, making it an environmentally friendly alternative. The production of valuable prebiotics, such as PMP-XOs, further enhances the economic viability of this approach.
In this work, a simple two-stage pretreatment (TSP) was utilized to improve hemicellulose separation and alleviate lignin condensation and therefore facilitate hemicellulose extraction and subsequent kraft pulping. In contrast to single-stage pretreatment, TSP showed a significant improvement for hemicellulose extraction and hemicellulose degradation and provided an almost identical cellulose loss. The hemicellulose separation efficiency was significantly improved using TSP with 60 min first followed by 30 min. More importantly, proper pretreatment is beneficial to the subsequent delignification; extensive pretreatment can retard delignification.
It has been demonstrated that radiation pretreatment can cause a significant breakdown of the stubborn cellulose structure, which will increase the accessibility of cellulose and enhance enzyme hydrolysis in bio-fuel processes. In this study, using microcrystalline cellulose (MCC) as a model substrate, the impacts of irradiation dose on the microstructure, thermal stability and irradiated-degradation components of cellulose under Co-60 gamma-irradiation (0-1400 kGy) was comprehensively investigated. FT-IR, EPR and NMR analyses show that irradiation destroys the glycosidic bond and inter- and intra-molecular hydrogen bond of cellulose, resulting in the generation of reductive carbonyl groups and free radicals. SEM, XRD and GPC analyses confirm that irradiation can damage the crystalline microstructure and surface morphology of MCC, which reduces its degree of polymerization from 183 045 kDa to 4413 kDa. TGA and DGA curves indicate that the activated energy (E-a) and thermal stability of treated MCC decrease with the increasing irradiation dose. Ion chromatography (IC) analysis demonstrates that there exist fermentation sugars such as glucose (10.73 mg g(-1)), xylose (1.58 mg g(-1)), arabinose (0.46 mg g(-1)), fructose (4.31 mg g(-1)), and cellobiose (1.90 mg g(-1)) as well as low amounts of glucuronic acid (0.35 mg g(-1)) and galacturonic acid (1.46 mg g(-1)) in the irradiation-derived degradation components. Therefore, the findings in this study suggest that gamma-irradiation processing is an environment-friendly, promising and effective approach to treat lignocellulose biomass.
The present study concerns the recovery of proteins from soybean hulls, mainly as oligopeptides, and the production of ethanol from the remaining lignocellulosic fraction. These goals were achieved using the following steps: hydrolysis of the soybean hulls by endoprotease Novo-ProD (R), acid hydrolysis of the lignocellulosic residue to remove hemicellulose, hydrolysis of cellulose by cellulolytic enzymes (Accellerase 1500 (R)), and alcoholic fermentation of the saccharified liquor. The proteolysis of the soybean hulls resulted in recovery of around 60\% of the proteins as small peptides (86\% with molar mass less than 6.5 kDa). The acid pretreatment removed more than 60\% of the hemicelluloses, allowing conversion of around 55\% of the cellulose to glucose in the enzymatic hydrolysis. In the fermentation with Saccharomyces cerevisiae, a yield of around 90\% was achieved, relative to the theoretical yield, representing an ethanol productivity of around 0.20 g/L/h for the integrated process. The results of this work indicate that soybean hulls might be a promising feedstock for the production of cellulosic ethanol and a high-value protein hydrolysate composed mainly of low molecular weight oligopeptides. (C) 2014 Elsevier B.V. All rights reserved.
In this paper a techno-economic and environmental analysis for a biorefinery based on Oil palm is presented in non-bioenergy regions of Colombia as a case study. Different scenarios, based on process sequences, were modelled and assessed. This includes a standalone biodiesel plant, a biodiesel plant with mass integration, a multiproduct portfolio to produce biodiesel, ethanol, and poly-3-hydroxybutyrate, and the multiproduct portfolio plus mass integration. The configuration with the best economic and environmental performance was the multiproduct portfolio plus mass integration. For this case, the obtained economic margin was 64.5\% (1.33 fold higher than standalone ethanol production), the potential environmental impact (PEI) was 156.42 PEI/t products and 051 t CO(2)eq/m(3) of biodiesel. On the other hand, the feedstock transportation was included to measure the influence on economics and carbon footprint indicator. For a travelled distance of 300 km the economic margin is decreased to 1.31\%, and the carbon footprint increased up to 0.59 t CO(2)eq/m(3) of biodiesel for scenario 4. (C) 2014 Elsevier Ltd. All rights reserved.
Liquid biofuels provide one of the few options for fossil fuel substitution in the short to medium-term and they are strongly being promoted by the European Union as transport fuel (such as ethanol) since they have the potential to offer both greenhouse gas (GHG) savings and energy security. A ``well to wheel{''
Food producers have leaned towards alternative natural and synthetic sweeteners in food formulations to satisfy market demands. Even so, several synthetic sweeteners (e.g., aspartame, saccharin, sucralose) are becoming less popular due to health-related concerns, lower nutritional values, and controversies around their safety. Conversely, natural sweeteners confer favourable customer perceptions due to their association to a healthier lifestyle and higher nutritional values. This article discusses the evidence of natural sweeteners in the available commercial products. A comprehensive review of natural sweeteners is presented, which includes their resources, properties and extraction methods, as well as a discussion on several emerging technologies that offer improvements to the traditional extraction methods. Finally, the progress of natural sweeteners in the food industry is assessed, and the commercial food products containing these natural sweeteners are mentioned.
A combined system based on multiple steam explosion pretreatments (direct pretreatment and presoaked in 1\% KOH aqueous solution followed by pretreatment under different conditions) and mild alkaline post-treatment has been developed to obtain digestible substrates from bamboo stems for bioethanol production. After the pretreatments, the enzymatic digestibility of cellulose increased to 17.1-32.2\%, as compared to that of the untreated bamboo stems (5.8\%). Direct pretreatment followed by alkaline treatment increased the enzymatic digestibility of cellulose to a maximum value of 73.8\%. Alkaline treatment removed most of lignin and hemicelluloses, and incurred a higher crystalline index of the celluloserich residue obtained after a synergistic treatment as compared to the only steam-exploded substrates. The combination of direct pretreatment and alkaline treatment is an environmentally friendly and economical feasible method for the production of glucose and high-purity lignin, which will be further converted into high value-added products based on biorefinery. (C) 2014 Elsevier Ltd. All rights reserved.
The need of developing renewable energy to reduce the impact on the global environment and climate change of the increasing industrial development has fostered the use of biological processes to produce biofuel from biohydrogen. The present work made a patent analysis of advanced hydrogen production techniques comparing it with similar prior art in China, Japan, the Republic of Korea, the European Union and the United States (U.S.) The aims were to find the scope, competitiveness of prior art, as well as the technology trend on biohydrogen production methods. The patents value was assessed its geographic scope and competitiveness indicators such as green image, low cost, energy efficiency and equipment design. It was found that most of the hydrogen production methods and associated technologies are developed by academic institutions, however their patents are reduced to a local level, and few are patented at international level, which reduces their competitiveness. The China (P.R.C.) is the biggest patent contributor worldwide in terms of hydrogen production methods by academic institutions. Japan is a huge patent contributor, in terms of methods aiming rear-end products application of hydrogen by private companies. The biggest amount of prior art found that the most popular methods of pretreatment and dark fermentation produced coincide with the time of energetic crisis and the green movement to find alternative fuels. Finally, patent analysis of this study can help to discern the current technology trend and to develop the next generation of biohydrogen processes and associated technologies. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
A plant waste, rubber (Hevea brasiliensis) leaf powder was modified with carbon disulfide (xanthation) for the purpose of introducing sulfur groups, and the adsorbent performance in removing Pb(II) ion was evaluated. Pb(II) adsorption was confirmed by spectroscopic analysis, which involved Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The amount of Pb(II) adsorbed increased with increasing pH, contact time and concentration but slightly decreased with increasing ionic strength. Adsorption equilibrium was achieved in less than 60 min and followed the pseudo-second order model. The isotherm data indicated that Pb(II) adsorption on xanthated rubber leaf (XRL) fitted well with Langmuir isotherm model. The maximum adsorption capacity computed from the Langmuir isotherm model was 166.7 mg/g. Pb(II) adsorption occurred via ion-exchange and complexation mechanisms.
Xylose-to-xylitol conversion was investigated in a bench-scale bioreactor using Candida guilliermondii cells entrapped within polyvinyl alcohol-hydrogel beads in a system operated in repeated-batch mode with cell recycling. Yeast-viable cells were immobilized in the support using the freezing-thawing method. Bioconversion assays were performed in a stirred tank reactor operated at 400-rpm agitation speed, 30 degrees C temperature, and 1.04-vvm air flow rate. The system was explored during six successive cycles, and a small decrease in the conversion performance in the fifth cycle was observed, but the biocatalytic activity of the microorganism was recovered in the sixth cycle after washing the particles. During the process, the hydrogel beads maintained their shape and size without appreciable deterioration. Xylitol production, yield factor, and volumetric productivity increased with progressive recycling of cells and achieved their maximum values (P-F = 39.7 g l(-1); Y-P/S = 0.77 g g(-1); Q(P) = 0.53 g l(-1) h(-1), respectively) after the third cell recycling, probably because of cells' adaptation to the medium.
Eucalyptus wood was pretreated with an integrated process based on hydrothermal and alkaline pretreatments. The structural changes of hemicelluloses during the pretreatments and the components of the hydrolysates were comprehensively characterized. Sugar and spectral analyses indicated that the hemicelluloses remained in the residues obtained at hydrothermal pretreatment under low temperatures were mainly composed of a (1 -> 4)-beta-D-Xylp backbone with 4-O-methyl-alpha-D-glucuronic acids attached at O-2 of the xylose together with various monosaccharides of rhamnose, arabinose, galactose, glucose, and mannose. The pretreatments resulted in serious degradation of hemicelluloses at high pretreatment temperatures. The distribution changes of the hemicelluloses in the cell walls during the integrated pretreatments were detected by Confocal Raman Microscopy, which revealed that the dissolution of hemicelluloses in different morphological regions was inhomogeneous, and the a large portion of hemicelluloses were removed from the secondary cell wall regions during the pretreatments. (C) 2019 Elsevier B.V. All rights reserved.
Selective valorization of lignin to achieve high value and commodity chemicals is attracting increasing attention. In this work, an efficient and reusable metal-based ionic liquid (MBIL) was developed for the selective tailoring of p-coumaric acid ester (pCA), a typical p-hydroxyphenyl (H) unit, into methyl p-hydroxycinnamate (MPC). Under optimized conditions and in the presence of catalyst {[
Reducing the formation of adsorbable organic halides during chlorine dioxide bleaching (the first stage chlorine dioxide bleaching, D-0) is necessary to obtain clean bleaching processes. A new bleaching agent, ammonium thiosulfate (AT), was investigated to determine its potential for reducing the amount of adsorbable organic halides (AOX). Upon investigating the optimal reaction conditions for an effective reduction in AOX, the authors determined that adding 0.20\% of AT 10 min after the beginning of the bleaching reaction, while maintaining a pH of 4 and a temperature of 70 degrees C, yielded the best results. Under these conditions, AOX formation decreased by 22.0\%. The bleaching effluent after the addition of AT was analyzed via gas chromatography-mass spectrometry, which showed an inhibited production rate of chlorobenzene and chlorophenol, which are both highly toxic and difficult-to-degrade compounds. Therefore, AT not only reduces AOX formation during the bleaching process, but also minimizes the difficulty of treating bleaching effluent. The results of this study provided a new, clean method for reducing AOX formation during chlorine dioxide bleaching.
Brewery liquid waste (BLW), brewery spent grain (BSG), apple pomace solid wastes (APS), apple pomace ultrafiltration sludge (APUS) and starch industry waste (SIW) were evaluated as alternative feedstocks for levulinic acid (LA) production via microwave-assisted acid-catalyzed thermal hydrolysis. LA production of 204, 160, 66, 49 and 12 g/kg was observed for BLW, BSG, APS, APUS, and SIW, respectively, at 140 degrees C, 40 g/L substrate concentration (SC), 60 min and 2 N HC1 (acid concentration). Based on the screening studies, BLW and BSG were selected for optimization studies using response surface methodology. Maximum LA production of 409 and 341 g/kg for BLW and BSG, respectively were obtained at 160 degrees C, 4.5 M HC1, 85 g/L SC and 27.5 min. Results demonstrated the possibility of using brewery wastes as promising substrates for economical and higher yield production of LA, a renewable platform chemical and versatile precursor for fuels and chemicals.
A biofilter with fungus was developed for efficient degradation of benzene, which can overcome the potential risk of leakage commonly found in such services. Results indicated that the optimum parameter values were temperature 40 degrees C, pH 6, and 500 mg L-1 of the initial benzene concentration. Besides, the empty bed residence time and inlet load range of biofilter were set to 20 s and 21.23-169.84 g m(-3) h(-1) respectively. Under these conditions, this biofilter can obtain the maximum removal efficiency of more than 90\%, the eliminating capacity could be up to 151.67 g m(-3) h(-1). Furthermore, scanning electron microscopy was used to investigate three filler materials for packing fungus biofilm. This is the first study introducing an Aspergillus strain for benzene removal and these results highlight that the development of this biofilter has the potential scaling-up application as gas-processing of industrial wastes.
Xylitol production from xylose by the yeast Candida magnoliae TISTR 5663 was enhanced by supplementing the fermentation medium with furfural (300 mg/L) and glucose (3 with an initial mass ratio of glucose to xylose of 1:10) together under oxygen limiting conditions. In the presence of furfural and glucose, the final concentration of xylitol was unaffected relative to control cultures but the xylitol yield on xylose increased by about 5\%. Supplementation of the culture medium with glucose alone at an initial concentration of 3 g/L, stimulated the volumetric and specific rates of Xylose consumption and the rate of xylitol production from xylose. In a culture medium containing 30 g/L xylose, 300 mg/L furfural and 3 g/L glucose, the volumetric production rate of xylitol was 1.04 g/L h and the specific production rate was 0.169 g/g h. In the absence of furfural and glucose, the volumetric production rate of xylitol was 35\% lower and the specific production rate was nearly 30\% lower. In view of these results, xylose-containing lignocellulosic hydrolysates contaminated with furfural can be effectively used for producing xylitol by fermentation so long as the glucose-to-xylose mass ratio in the hydrolysate does not exceed 1:10 and the furfural concentration is <= 300 mg/L. (C) 2016 Elsevier B.V. All rights reserved.
A surface wave discharge (SWD) in argon at atmospheric pressure generated by a surfatron device was studied by optical emission spectroscopy (OES). Two distinct situations were investigated; (i) a discharge plasma in open air and (ii) a discharge plasma totally confined in a quartz tube. The electron density ne, electron temperature T-e and gas temperature T-g were investigated as a function of applied power and gas flow rate. The self-absorbing method was used to estimate the population of the metastable state Ar(1s(5)). These physical quantities were determined through optical measurements along the plasma axis of symmetry. The profile of the electron density presented a maximum value under certain conditions, in contrast with typical electron density profiles of SWDs which are usually monotonically decreasing. A correlation between the electron density and the metastable state Ar(1s(5)) was found in one of these cases, suggesting that stepwise ionization from metastable states and non-local kinetics play an important role on the unexpected increase in ionization degree along the discharge.
We investigated the feasibility of producing bioethanol from mixed softwood pretreated with the ionic liquid 1-butyl-3-methylimidazolium acetate ({[
In recent decades, advancements in lignin application include the synthesis of polymers, dyes, adhesives and fertilizers. There has recently been a shift from perceiving lignin as a waste product to viewing lignin as a potential raw material for valuable products. More recently, considerable attention has been placed in sectors, like the medical, electrochemical, and polymer sectors, where lignin can be significantly valorized. Despite some technical challenges in lignin recovery and depolymerization, lignin is viewed as a promising material due to it being biocompatible, cheap, and abundant in nature. In the medical sector, lignins can be used as wound dressings, pharmaceuticals, and drug delivery materials. They can also be used for electrochemical energy materials and 3D printing lignin-plastic composite materials. This review covers the recent research progress in lignin valorization, specifically focusing on medical, electrochemical, and 3D printing applications. The technoeconomic assessment of lignin application is also discussed.
This study aimed to evaluate the synergism of cellulases and amylolytic enzymes in the hydrolysis of microalgal carbohydrates for bioethanol production. The effect of -glucosidase on the hydrolysis of algal cellulose, and the comparison between the effect of the addition of -amylase and amyloglucosidase separately or together on the hydrolysis of algal starch, have not been described previously. Results showed that -glucosidases promoted the enzymatic hydrolysis of algal cellulose as a result of the increase in the glucose production rate and the decrease in the inhibition by cellobiose. It was also beneficial to carry out the hydrolysis of algal starch using the mixture of -amylase and amyloglucosidase. The results obtained revealed that, in enzymatic hydrolysis experiments, simultaneous treatment with Celluclast 1.5L, -glucosidase, -amylase, and amyloglucosidase was a promising strategy to reduce the hydrolysis time required to achieve a higher yield of glucose. Subsequently, fermentation of enzymatic hydrolysates of microalgae using Saccharomyces cerevisiae showed a yield of 0.126g ethanol / g dried algae. (c) 2018 Society of Chemical Industry and John Wiley \& Sons, Ltd
Wood-based plastics obtained via chemical modifications are usually dark and opaque, which limits their potential applications. All-wood plastics (AWPs) derived from ball-milled mulberry wood (BMMW) via an efficient heterogeneous esterification for 2 h in dimethyl sulfoxide (DMSO)/1-butyl-3-methylimidazolium chloride (BMIMCl) with the molar ratios of DMSO to BMIMC1 at 5.9:1 exhibit a highly translucent appearance. With desirable thermoplasticity and tensile strength, AWPs can be processed into light-permeable specimens and transparent film. FT-IR and solid-state C-13 NMR spectra provide evidence for successful substitution of hydroxyl groups of BMMW by carboxybenzoyl groups. The darkness of AWPs arising from the oxidation of phenolic lignin into benzoquinone indicates that reaction time plays a critical role for controlling the transparency of AWPs. AWPs represent composite structures, including cellulose I and cellulose II. Different degradation mechanisms are observed among AWPs differently esterified. Moreover, the SEM and AFM images demonstrate the self reinforcement of AWPs specimens and the heterogeneous surface of a transparent AWP film, respectively.
This paper focuses on the production of magnetic biochar through a novel vacuum condition in an electrical muffle furnace by employing durian rind as the raw material in the presence of three different metallic salts. A high BET surface area value of 835 m(2) g(-1) was attained at the pyrolysis temperature and time of 800 degrees C and 25 min. This magnetic biochar was embedded with polypyrrole (PPY) through an in situ polymerization process which improved specific capacitance of the polymer composite compared to the pure PPY and magnetic biochar. The MBCP composite exhibited the highest specific capacitance of 572 F g(-1) and energy density of 71.50 Wh kg(-1) compared to other existing PPY coated carbon composite. This MBCP composite exhibits a good potential for future low-cost supercapacitor applications with an impressive specific capacitance and energy density value. (C) 2017 Elsevier Ltd. All rights reserved.
Furfural residues (FRs) is an industrial waste material with an enormous potential for bio-ethanol production. In this study, FRs were pretreated with green liquor (GL) combined with hydrogen peroxide (GL H2O2) or ethanol (GL-ethanol). The wettability and electrostatic contributions of untreated and pretreated FRs was investigated as well as that of isolated lignin cellulolytic enzyme lignin (CEL) and cellulose. The results showed that the hydrophilicity of FRs was increased after GL-H2O2 and GL-ethanol pretreatment. Lignin is the key factor that affects the hydrophilicity of substrate. The cellulase binding for lignin was reduced due to the increase of hydrophilicity of lignin, resulting in the improvement of enzymatic hydrolysis. The electrostatic contributions was also an important factor that influenced the cellulase binding of lignin. After pretreatments, the negative charge of lignin was decreased. Accordingly, the cellulase binding capacity was reduced. This effect was more significant after the GL-ethanol pretreatment. Thus, the glucose yield of the substrate obtained from the GL-ethanol pretreatment (86.1 \%) was larger than that from the GL-H2O2 pretreatment (82.2 \%). Unlike the CEL, GL-H2O2 pretreatment increased the negative charge of cellulose. And the increase of negative charge improved the affinity of cellulose to cellulase via electrostatic attraction. The XPS analyses indicated that the carbonyl groups from lignin play an important role in decreasing the hydrophobicity of the substrates.
The use of low-cost adsorbent papaya leaf was investigated as a replacement for current costly methods of removing methylene blue dye (MB) from the aqueous solution. The adsorption equilibrium was determined as a function of contact time, initial adsorbate concentration, and solution pH. The adsorptive uptake of MB increased with increasing the initial MB concentration and solution pH. The adsorption isotherms were correlated with a comparison of linear and nonlinear regression analysis. Langmuir isotherm model provided the best-fit for the adsorption of MB onto papaya leaf, with a maximum monolayer adsorption capacity of 231.65 mg/g. This locally available adsorbent was found to be low cost and promising for the remediation of textile wastewater.
Natural lignocellulosic fiber epicarp extracted from the babassu coconut (Orbignya speciosa) was chemically modified through reaction with molten maleic anhydride without solvent, with incorporation of 189.34 mg g(-1) of carboxylic acid groups into the biopolymer structure. The success of this reaction was also confirmed by the presence of carboxylic acid bands at 1741 and 1164 cm(-1) in the infrared spectrum. Identically, the same group is observed through C-13 NMR CP/MAS in the solid state, via high field signals in the 167 pm region. Both the precursor and the immobilized maleated biopolymers presented nearly the same thermal stability and similar crystallinity to cellulose. However, the pendant carboxylic groups have the ability to remove copper with maximum sorption through a batchwise process at pH 6.0, as expected from the point of zero charge, determined to be 6.45. The sorption kinetic data were fitted to pseudo-first order, pseudo-second order, Elovich-chemisorption and intra-particle diffusion models and the equilibrium data were fitted to the Langmuir, the Freundlich and Tenkim isotherm models. Taking into account a statistical error function and determination coefficients, the data were fit to the pseudo-first and pseudo-second order kinetic and Langmuir isotherm models, with a maximum sorption capacity of copper ions of 55.09 mg g(-1). This value suggests the application of this biopolymer with incorporated carboxylate groups as a favorable agent for copper removal from appropriate systems.
Biomass from three invasive plant species of the Western Karoo region in South Africa, namely Kraalbos, Schotzbos and Asbos, was treated by vacuum pyrolysis. The influence of temperature, pyrolysis time, pressure and initial moisture content on the bio-oil and charcoal yields were investigated. Asbos with the largest ash content, 19.9 wt.\%, gave chars with an ash content between 40 wt.\% and 44 wt.\% making it difficult to use commercially. Vacuum pyrolysis of Kraalbos resulted in producing a biochar with a HHV of 23.0-25.5 MJ/kg and an ash content of 13-19 wt.\% which compared favourable with commercial charcoal. The bio-oils from both Kraalbos and Schotzbos showed promise as potential heating oil with a HHV of 21.6-26.9 MJ/kg. The tarry phase contained a number of phenolic compounds that can be separated and shows promise as a feedstock for upgrading. Finally ageing which acts on the lignocellulosic structure of biomasses decreased the charcoal and oil yields from the vacuum pyrolysis of intruder plants. (C) 2011 Elsevier B.V. All rights reserved.
Xylo-oligosaccharides (XOS) are emerging prebiotics that have recently been gained a great interest in the market of functional foods. Since their beneficial activity strictly depends on their chemical structure and on their degree of polymerization (DP), in this work an enzymatic method was developed to produce XOS with variable and modellable DPs, involving a combination of a commercial endo-beta-1,4-xylanase M3 from Trichoderma longibrachiatum and a deacetylase, using a commercial acetylated standard xylan as substrate. A Design of Experiment (DoE) was developed and through the variation of some hydrolysis conditions, some experiments allowed to obtain significant amounts of XOS with DP 7-10, up to 11\%, despite XOS with DP 2-4 were always the most abundant (60-96\% of total XOS). The most impacting parameter on the XOS distribution was the order of addition of the xylanase and deacetylating enzyme, while pH showed to have a great influence on the total yield. The method was also tested on an acetylated xylan extracted from grape stalks, structurally similar to the commercial standard xylan. The model was found to work in a very similar way also on the non-purified xylan sample, allowing the manipulation of enzymatic hydrolysis on a low-cost by-product, with the potential to obtain on a large scale XOS with high added value and with a specific DP, depending on the final application.
A comprehensive study was carried out to assess the efficiency of different chemicals on the pretreatment of plant biomass, corn cobs. The efficiency was assessed based on its effect on subsequent hydrolysis of biomass for the conversion to fermentable sugars. Both alkali- and acid-based pretreatments were carried out under optimized conditions to avoid the formation of inhibitors and also to yield more sugars. Among the different chemicals used, 2\% NaOH (w/v) was found to be effective with the delignification efficiency of 84.32\%, and furthermore, the biomass saccharification efficiency was found to be 86.28\% using 1.20\% (v/v) HNO3 at 100 degrees C for 90 min, whereas the pretreatment with other chemicals such as KOH, NaClO2, Na2SO3, and NH3 had significantly (p < 0.05) low delignification, which ultimately reduced the saccharification efficiency. In acid-base-based pretreatment, 1.5\% (v/v) HNO3 resulted in 63.42\% delignification along with 68\% digestion of hemicelluloses. The effect of pretreatment efficiency on digestibility was investigated by biomass characterization using SEM, FTIR, and XRD analyses before and after the treatment process. The imaging studies clearly indicated that 2\% NaOH efficiently digested the complex matrix alignment and enhanced the surface area of the carbohydrate polymer which had shown a positive impact on the rate of hydrolysis. The study concludes that alkali-based pretreatment is the efficient and cost-viable technique for the effective valorization of corn cobs for the production of fermentable sugars which can be further converted to various valuable bioproducts.
In this work, naturally dispersed ash components in bio-carbon composites were prepared from waste spent mushroom substrate. Two kinds of deashing treatments were used to study the role of soluble and poorly soluble ash in the adsorption of NH4+ and increase specific surface area. The role of ash components on pore structure and the adsorption of ammonia nitrogen were systematically investigated. It is revealed that the relationship of ammonium adsorption capacity of three ACs is MAC > MAC-W > MAC-A at the varied pH conditions. Specifically, the ammonia nitrogen adsorption capacity of MAC increases 108.9\% as compared with MAC-A. The bigger pore structure and BET of carbon was obtained after absorption due to naturally dispersed ash components exchanged with NH4+. What is more, Na+, K+, and Ca2+ in the ash have a greater effect on the adsorption of ammonia nitrogen of ACs. The struvite formation will consume the Mg2+ and NH4+ ion, leading to the enhanced adsorption properties via chemical deposition. This work provides a new perspective on dispersed ash components in bio-carbon from the low-valued biomass for the ammonia nitrogen removal and specific surface area augment.
Degumming is the dominant method for insolating lignocellulosic fibers in textile applications. Traditional alkaline degumming (TAL), as a common method, requires a high-concentration alkali and has been a severe challenge to the environment. In the research reported here, the possibility of innovative jute degumming by organic solvents 1-2 propylene glycol and a combination of additive green oxygen (GO-OS) was studied. The results revealed that fibers could be extracted by this system (under condition of 0.9\% GO-OS, 180 degrees C, 120 min), and obtained fibers with higher breaking tenacity (7.1 cN/dtex), yield (65.7\%), breaking elongation (2.87\%) and residual gum (11.7\%), which all meet the requirement of the relevant Chinese Textile National Standards. Notably, the required reaction time (120 min) of the GO-OS system was 180 min shorter than that of the TAL method. Furthermore, the modifications introduced by the degumming effect on physicochemical aspects were characterized and confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. This study provides a promising degumming method for separating jute lignocellulose without acid and alkali consumption.
Background The optimal use of feed resources must be considered by most livestock farmers. The use of low-cost agricultural by-products and the processing of these materials is one possible solution in this respect. One such compound is edible button mushroom waste (EM), a large amount of which is produced annually in the mushroom production cycle worldwide. Results Bulk density 100 of EM was smaller than the other groups. These changes also applied to alfalfa for bulk density, which was higher than the replaced waste. The dry matter solubility of EM was higher than that of alfalfa hay, whereas the ash solubility rate for EM was greater compared to alfalfa. Replacing up to 210 g kg(-1) alfalfa with EM did not affect the production of purine derivatives, microbial protein, nitrogen excreted in urine and feces, and retained nitrogen, although the organic matter digestibility (OMD) increased, whereas the crude protein digestibility and neutral detergent fiber (NDF) decreased (P < 0.05). Fermentation potential, gas production rate, metabolizable energy and short-chain fatty acids were increased. On replacing up to 210 g kg(-1) alfalfa with EM, the diet OMD increased, whereas the crude protein and NDF digestibility decreased (P < 0.05). Conclusion EM usage in the experimental diets did not affect the production of purine derivatives, microbial protein, nitrogen excreted in urine and feces, and retained nitrogen. The physical properties, chemical composition and nutritional value of EM, as well as its low cost, show that it can be used as an alternative part of the diet forage in the ruminant's diet. (c) 2021 Society of Chemical Industry.
Spent mushroom compost (SMC), waste cultivation medium of mushroom, is a potential lignocellulosic substrate. The characteristics of Clostridium thermocellum growing on SMC were investigated to provide practical guidance for better utilizing the SMC. SMC could be utilized without any pretreatment by C. thermocellum, and grinding, washing and mild chemical pretreatment could improve the fermentation performance of SMC, and consequently improved the hydrogen production. Grinding, washing and NaOH pretreatment increased hydrogen production by 48.48\%, 62.09\% and 2.61 times, respectively. Compared with washing method, neutralizing the alkali pretreated SMC with waste acid had no significant effect on hydrogen production, while could save a lot of water. Besides, fermentation without sterilization and medium simplification were feasible for the fermentation of SMC. The present study shows that SMC is a feasible substrate for consolidated bioprocessing, but pretreatments are needed to degrade the SMC more effectively. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
this study, we investigated cellulase production by Penicillium oxalicum EU2106 under solid-state fermentation (SSF) and its hydrolysis efficiency toward NaOH-H2O2-pretreated cassava residue (NHCR) produced after bioethanol fermentation. Optimization of SSF cultivation conditions for P. oxalicum EU2106 using a Box-behnken design-based response-surface methodology resulted in maximal cellulase activity of 34.0 +/- 2.8 filter-paper units/g dry substrate, exhibiting a similar to twofold increase relative to activities obtained under non-optimized conditions. Furthermore, SSF-derived cellulase converted 94.3 +/- 1.5\% of NHCR cellulose into glucose within 96 h. Interestingly, P. oxalicum EU2106 produced higher beta-glucosidase activity under SSF conditions than that under submerged-state fermentation conditions, resulting in the elimination of cellobiose inhibition during the early stages of NHCR cellulose hydrolysis. Overall, this work provided an alternative for a potential cellulase source and a preferred option for cassava residue biotechnological application.
A novel type of adsorbent (CM) was synthesized by cellulose modified with maleic anhydride to remove heavy metal ions and organic dyes in this work. The synthesized adsorbent was characterized by FTIR, SEM, TGA and XRD. The degree of carboxyl group of CM was found to be 2.7 mmol g(-1) by the titration method. The adsorption of Hg(II) ions as heavy metal ions while basic fuchsine, methylene blue and crystal violet as organic dyes by CM was investigated. The influence of different experimental parameters such as pH, contact time, temperature on removal process was evaluated. The results indicated that the CM has a good adsorption capacity for Hg(II). The maximum adsorption capacity of Hg(II) was found to be 172.5 mg g(-1), and the adsorption process was described by Freundlich isotherm model of adsorption well. The process of basic fuchsine, methylene blue and crystal violet adsorbed by CM was also studied and the adsorption removal rate of those organic dyes was 88.10, 98.47 and 92.85 \% under the optimum conditions, respectively. The adsorption process was depicted by the Langmuir isotherm model more correctly.
Reducing carbon emissions has become the current focus of attention all over the world. Alternative biofuels are an important means to achieve the carbon reduction. Among them, hydrothermal liquefaction (HTL) of algaebased biomass has been widely studied because of its environmental friendliness and mild conditions. In this paper, the effect of different conditions on microalgae bio-crude enhancement was investigated, using innovative experimental methods, including flash heating HTL with two step or by co-solvent. It showed that recovery of carbon, hydrogen and energy could reach 0.53, 0.48 and 0.58 respectively at 250 degrees C for 30 min with ethanolwater co-solvent as the medium. The highest total content of fatty acids and fatty acid esters were found in the bio-crude with methanol/ethanol-water co-solvent as the medium. The nitrogen content of the bio-crude obtained by the two-step method is lower than that of the one-step method. The content of cholesterol and vitamin E as indicators of bioactive substances performed well with ethanol-water co-solvent as the liquid phase medium, containing 16.1\% in bio-crude at 240 degrees C for 3 min, and also advantageously with air as the gas phase medium.
A deep eutectic solvent (DES), consisting of choline chloride and oxalic acid (ChCl-OX), was used to pretreat corncob. Three different recycling procedures were evaluated in terms of the composition analysis, efficiency of enzymatic hydrolysis, inhibitors formation, XRD and FTIR analysis. The results demonstrated that there were two key factors affecting the pretreatment efficiency for reusing DES, the addition of oxalic acid and the removal of lignin from the recycled ChCl-OX. After ten recycles, the pretreatment efficiencies of the recycled DES, using recycling process with supplemented oxalic acid and removal of lignin from the recovered DES, did not obviously decrease the glucan digestibility and glucose recovery (66.23\% and 64.43\%, respectively) compared to the original DES pretreatment (72.83\% and 68.83\%, respectively). The contents of fermentation inhibitors were not obviously increased in the enzymatic hydrolysates, and the cost and pollution were further reduced after the reuse of solvents and recovery of lignin. This study suggests that this recycling method maybe a green, low-cost procedure of biomass pretreatment.
The development of cassava starch-based biocomposites incorporated with pecan nutshells and pinhao shells by thermocompression process was evaluated. The biocomposites were characterized in terms of thickness, bulk density, hydrophilicity, water absorption capacity (WAC), morphology, thermal and mechanical properties. The samples with residues incorporation showed lower WAC when compared to the control ones, for all evaluated times. Biocomposites containing the pinhao shells showed hydrophobic character, measured by the contact angle (greater than 90 degrees). More irregularities were evidenced by the morphological analysis for the biocomposites added with pecan nutshells. The thermal stability of the biocomposites was influenced by the high lignin content in the residues. Regarding the mechanical properties, in both tensile and flexural tests, biocomposites containing pecan nutshells presented the lowest values of stress at break and modulus of elasticity. When compared to the control sample, the composites added with the pinhao shells had mechanical similar properties, differently from the result for samples incorporated with pecan nutshells that presented less resistant.
Sequential solid-state and submerged cultivation with various lignocellulosic biomasses as a substrate for lignocellulolytic enzyme production by Pleurotus ostreatus were assessed by measuring endoglucanase, xylanase, and laccase activities. An unconventional preculture method was established by cultivating the P. ostreatus mycelia in a solid substrate medium for an initial fungal growth phase, followed by a transition to submerged fermentation through adding a liquid culture medium. The lignocellulolytic enzymes of P. ostreatus in different fermentation methods revealed wide differences. The higher yields of endoglucanase (3152 +/- 139 U/L), xylanase (3064 +/- 40 U/L), and laccase (543 +/- 21 U/L) were achieved by using the sequential solid-state submerged method compared to conventional solid-state and submerged cultivation. Generally speaking, sequential solid-state and submerged fermentation of cottonseed hull is favorable for laccase secretion, whereas sequential solid-state and submerged fermentation of corncob provides better production of hydrolytic enzymes. These results revealed that the nature of the lignocellulosic biomass and the fermentation method play an important role in the expression of lignocellulolytic enzymes. This indication would be helpful in optimizing the production of integrated industrial lignocellulolytic enzymes.
The objective of this study was to investigate the pyrolysis of mushroom spent compost (MSC) by laboratory microwave to produce bio-oil and evaluate its life cycle assessment (LCA). In the first part of this study, MSC was used as a substrate for bio-oil production and the optimization of the production conditions through the response surface method (RSM). Optimal conditions for the production of pyrolysis products as the amount of catalyst 8.95\%, microwave power of 441.21 W with any catalyst (preferably coal) for the maximum amount of bio-oil (37.39\%), bio-char (33.63\%), and gas (28.97\%) were identified. In the second part of this study, its LCA was assessed by the integrated waste management (IWM) model. The results showed that in terms of energy consumption and acidification, scenario one (waste composting) has the worst performance and in terms of greenhouse gases, photochemical fog, and release of toxic substances into the climate, the second scenario (microwave pyrolysis) has the worst are performance. LCA was assessed by the IWM model. The results showed that in terms of energy consumption and acidification, scenario one (waste composting) has the worst performance and in terms of greenhouse gases, photochemical smog, and emission of toxic substances into the climate, the second scenario (microwave pyrolysis) has the worst performance.
Mining activity is essential for the social welfare of the population. However, this activity produces a series of mining waste. These mining wastes, if not properly treated, can produce significant environmental pollution. This study develops the incorporation of tailings from washing plants in ceramic materials for bricks in order to retain the contaminating elements in the ceramic matrix. To this end, firstly, a physical and chemical characterisation of the mining waste is carried out and different groups of samples are conformed with clay and mining waste. These conformed samples with mining waste are evaluated through different physical and mechanical tests typical in the ceramic industry, studying the variation of properties by the incorporation of the waste. In turn, the leachates from the groups of conformed samples are analyzed, confirming the retention of the contaminating elements of the mining waste in the ceramic matrix. The results of these tests showed that ceramics can be made for bricks with up to 90\% mining waste, obtaining physical and mechanical properties acceptable regarding the regulations and retaining the contaminating elements in the ceramic matrix, as confirmed by the leachate tests.
It is a great challenge to efficiently utilize xylose in fermentation with high solid loadings for the economically feasible production of lignocellulosic ethanol. However, 20\% solid loading of dry dilute acid pretreated corn stover (DDAPCS) decreased 66.3\% of the xylose consumption compared to yeast extract peptone dextrose and xylose (YPDX) medium, which was significantly larger than 16\% solid loading (9.4\%). To overcome those problems, several two-step processes for simultaneous saccharification and co-fermentation (SSCF) were developed by inoculating a water extract of 16\% solid loading DDAPCS with microorganisms in the first fermentation step. During the first step, the relatively lower inhibitor concentrations (compared to 20\% solid loading), decreased glucose concentration, and the absence of enzymatic hydrolysis residues (EHR) were beneficial for the use of xylose and enabled up to 75.6\% of the xylose to be converted to ethanol. With an optimized fed-batch strategy of two-step process, the residual xylose concentration reduced by 55.6\% with 20\% solid loading, and the maximum ethanol concentration and yield increased by 30\% and 16.6\%, respectively. (C) 2018 Elsevier Ltd. All rights reserved.
This study investigated the effect of high-temperature saturated steam treatments on the chemical characteristics and enzymatic saccharification of softwood and hardwood. The weight loss and chemical modification of cedar and beech wood pieces treated at 25, 35, and 45 atm for 5 min were determined. Fourier transform infrared and X-ray diffraction analyses indicated that solubilization and removal of hemicellulose and lignin occurred by the steam treatment. The milling treatment of steam-treated wood enhanced its enzymatic saccharification. Maximum enzymatic saccharification (i.e., 94\% saccharification rate of cellulose) was obtained using steam-treated beech at 35 atm for 5 min followed by milling treatment for 1 min. However, the necessity of the milling treatment for efficient enzymatic saccharification is dependent on the wood species. (c) 2015 Elsevier Ltd. All rights reserved.
Cellulose nanocrystals (CNC) were used as a novel, green eluent to remediate Cd-contaminated soil in this study. The influence of washing conditions on the removal of Cd, including CNC concentration, pH value, liquid/solid (L/S) ratio, contact time and temperature were investigated. The effect of CNC remediation of Cd-contaminated soil on soil health and the possible remediation mechanism were also explored. The results showed that CNC concentration, pH value and contact time had a significant effect on the removal efficiency of Cd. CNC rapidly removed heavy metals in soil within 30 min. When the pH value of the eluent was 9.0, the removal efficiency of Cd could reach 86.3 \%. The eluent mainly removed exchangeable and reducible fractions of Cd, which could effectively reduce the bioavailability of heavy metals. CNC washing had no negative effects on seed growth, species abundance and Shannon index. C-O, -COO- groups on CNC played an important role in the reaction between CNC and soil Cd, and other oxygen-containing functional groups on CNC could also assist in adsorption, ion exchange and chemical complexation processes. Therefore, cellulose nanocrystals had the potential to remediate heavy metal-contaminated soils in a green and efficient manner.
In this study, spark plasma sintering (SPS) was performed using calcareous waste concrete powder. In particular, we examined the sintering temperature for SPS. This improved the flexural strength and flexural modulus. Two types of calcareous waste concrete powders were prepared: waste mortar powder (WMP) and waste coarse aggregate powder (WCAP). The characteristics of the sintered bodies were evaluated using a three-point flexural test and powder X-ray diffraction (XRD). As the main crystalline component of the raw powder, WMP included calcite and quartz, and WCAP included calcite and hematite. Regarding the flexural strength of the sintered body, WMP had 52.6 MPa at a sintering temperature of 900 ?C, and WCAP had 42.4 MPa at a sintering temperature of 850 ?C. These values are higher than the value of 35 MPa of ISO 13,006 standard, which prescribes porcelain stoneware tiles. XRD analysis reveals the synthesis of spurrite, gehlenite, wollastonite, and larnite in WMP, and in WCAP, spurrite and magnetite are confirmed. The synthesis of these chemical compounds is attributed to the decarbonation reaction of calcite at 760 ?C. Therefore, calcareous concrete can be used as a raw material for construction ceramics when applied to SPS.
Aromatic sulfonic acid, p-toluenesulfonic acid (p-TsOH), was employed to pretreat the corn stover in aqueous for improving the enzymatic hydrolysis of cellulose-enriched residue, and was compared to ethanol/water pretreatment. The glucose yield of corn stover from p-TsOH/water pretreatment (97.6 \%) was higher than that from ethanol/water pretreatment (89.5 \%) after 96 h hydrolysis with high cellulase loading of 15 FPU/g-cellulose. More than 80 \% of glucose yield was still obtained with low cellulase loading (7.5 FPU/g-cellulose) after p-TsOH/water pretreatment, while only 65.2 \% was obtained after ethanol/water pretreatment. Composition and structure analysis showed that p-TsOH/water pretreatment severely break the fibre, removed more lignin (especially of surface lignin), well increased cellulose accessibility, and resulted in more hydroxyl exposed on the surface. Moreover, more monomeric sugars (xylose and glucose) derived from hemicellulose were released after p-TsOH/water pretreatment, and they could be converted to valuable platform chemical of levulinic acid by simply heating the prehydrolysate.
In the third part of this series of studies, the adsorption of the basic textile dyes auramine-O (AO) and safranin-T (ST) on a carboxylated cellulose derivative (CTA) were evaluated in mono- and bicomponent spiked aqueous solutions. Adsorption studies were developed as a function of solution pH, contact time, and initial dye concentration. Adsorption kinetic data were modeled by monocomponent kinetic models of pseudo-first- (PFO), pseudo-second-order (PSO), intraparticle diffusion, and Boyd, while the competitive kinetic model of Corsel was used to model bicomponent kinetic data. Monocomponent adsorption equilibrium data were modeled by the Langmuir, Sips, Fowler-Guggenhein, Hill de-Boer, and Konda models, while the LAST and RAST models were used to model bicomponent equilibrium data. Monocomponent maximum adsorption capacities for AO and ST at pH 4.5 were 2.841 and 3.691 mmol g(-1), and at pH 7.0 were 5.443 and 4.074 mmol g(-1), respectively. Bicomponent maximum adsorption capacities for AO and ST at pH 7.0 were 1.230 and 3.728 mmol g(-1). Adsorption enthalpy changes (Delta H-ads) were obtained using isothermal titration calorimetry. The values of Delta H-ads ranged from -18.83 to -5.60 kJ mol(-1), suggesting that physisorption controlled the adsorption process. Desorption and re-adsorption of CTA was also evaluated. (C) 2017 Elsevier Inc. All rights reserved.
We investigated the enzymatic complex produced by selected fungi strains isolated from the environment using the agro-industrial residues rice husk, soybean hull, and spent malt as substrates. Microbial growth was carried out in solid-state cultivation (SSC) and in submerged cultivations (SC) and the enzymatic activities of xylanase, cellulase, beta-xylosidase, and beta-glucosidase were determined. All substrates were effective in inducing enzymatic activities, with one strain of Aspergillus brasiliensis BLf1 showing maximum activities for all enzymes, except for cellulases. Using this fungus, the enzymatic activities of xylanase, cellulase, and beta-glucosidase were generally higher in SSC compared to SC, producing maxima activities of 120.5, 25.3 and 47.4 U g(-1) of dry substrate, respectively. beta-xylosidase activity of 28.1 U g(-1) of dry substrate was highest in SC. Experimental design was carried out to optimize xylanase activity by A. brasiliensis BLf1 in SSC using rice husk as substrate, producing maximum xylanase activity 183.5 U g(-1) dry substrate, and xylooligosaccharides were produced and characterized. These results suggest A. brasiliensis BLf1 can be used to produce important lytic enzymes to be applied in the preparation of xylooligosaccharides.
Meranti wood sawdust (MWS) is a lignocellulosic waste of sawmill which can be used as a promising source of xylose. The main application of xylose is its bioconversion to xylitol, a high value product. The growing interest in biotechnological production of biofuels and specialty chemicals from lignocellulosic waste is justifiable as these materials are low priced, renewable and widespread sources of sugars. The aim of this research was to study xylose production from MWS by acid hydrolysis. Batch hydrolysis was conducted at 130 degrees C using several concentrations of H2SO4 (2-6\%) and residence time (0-120 min). The kinetic parameters of mathematical models were determined to predict xylose, glucose, furfural, and acetic acid concentration in the hemicellulosic hydrolysate. Optimum sulfuric acid concentration and residence time obtained were 6\% and 20 min, respectively. These conditions yielded a hydrolysate containing 18.5, 4.2, 0.4, and 4.1 g/I xylose, glucose, furfural, and acetic acid, respectively. The yield of xylose was more than 89\% of the potential concentration. (C) 2011 Elsevier Ltd. All rights reserved.
High-temperature pyrolytic detoxification reactions based on thermal analysis facilitate the resource reuse of solid waste from the biopharmaceutical industry. This study described thermodynamic parameters, gas by-products, and safety assessment. The most common emissions (H2O, O, NH3) peak at 345-440 degrees C, accompanied by a shift in the micro-interfacial reaction mechanism, resulting in the largest rate of weight loss and the most significant release of gaseous by-products from the reaction. The peak CO2, SO2, and N-2 emissions were dominated by deamination and sodium enrichment reactions, following the Mampel Power law mechanism. The growth trends of protein-nucleated Chlorella indicated the safety of the product at each stage. Compared to sample 375, sample 440 promoted the growth of Chlorella to a certain extent (maximum boost of 0.24 g center dot L-1 center dot d(-1)), indicating non-toxicity and neutral pH, which may be due to a shift in pH to neutral as a result of pyrolytic detoxification, thus increasing safety and facilitating resource recovery. Possible reaction pathways for the pyrolysis of solid products were derived, and the availability of end products that contribute to the safe reuse of final value-added products from biopharmaceutical waste.
In this study, the relationships between ethanol yield, concentration and solid loading (6-21\%) were investigated to enhance ethanol titer and avoid a random choice of solid loading for simultaneous saccharification and fermentation (SSF). Alkali-pretreated hemp biomass was used for SSF in four scenarios including Case I: 30 filter paper unit (FPU)-cellulase and 140 fungal xylanase unit (FXU)-hemicellulase/g-solid; Case II: 40 FPU-cellulase and 140 FXU-hemicellulase/g-solid; Case III: 30 FPU-cellulase and 140 FXU-hemicellulase/g-solid with 1\% Tween80; and Case IV: 30 FPU-cellulase and 140 FXU-hemicellulase/g-solid with particle size reduction (<0.2 mm). Results showed that bioethanol yield and concentration had a negative linear (R-2 = 0.76-0.93) and quadratic (R-2 = 0.96-0.99) correlation with solid loading (6-21\%), respectively. As compared to Case I and previous studies, an enhancement in ethanol yield and concentration through increasing cellulase dose (Case II) and adding Tween 80 (Case III) was overestimated, whereas particle size reduction (Case IV) extended the ``solid effect{''
Biodegradable cassava starch-based foams incorporated with grape stalks were obtained by thermal expansion. The morphology (SEM), chemical structure (FTIR), crystallinity (XRD), and biodegradability of the foams were evaluated. An applicability test was performed in the storage of food. SEM images showed no residue agglomerations and cell structure generally observed in materials obtained by thermal expansion; FTIR analysis verified interactions of foam components. XRD analysis showed native cassava starch characteristic peaks and the loss of crystallinity after the expansion process, with the formation of an amorphous material. Foams were completely biodegraded after 7 weeks, demonstrating that, for the experimental conditions used, the interactions between the starch and the grape stalks did not generate recalcitrant compounds or structural alterations that would impair foam degradation. Furthermore, the foams added with grape stalks presented good properties in the applicability test, showing a promising application in the storage of foods with low moisture content.
Efficient yet economic production of biofuel(s) using varied second-generation feedstock needs to be explored in the current scenario to cope up with global fuel demand. Hence, the present study was performed to reveal the use of cauliflower waste for acetone-butanol-ethanol (ABE) production using Clostridium acetobutylicum NRRL B 527. The proximate analysis of cauliflower waste demonstrated to comprise 17.32\% cellulose, 9.12\% hemicellulose, and 5.94\% lignin. Drying of cauliflower waste was carried out in the temperature range of 60-120 degrees C to investigate its effect on ABE production. The experimental drying data were simulated using moisture diffusion control model. The cauliflower waste dried at 80 degrees C showed maximum total sugar yield of 26.05 g L-1. Furthermore, the removal of phenolics, acetic acid, and total furans was found to be 90-97, 10-40, and 95-97\%, respectively. Incidentally, maximum ABE titer obtained was 5.35 g L-1 with 50\% sugar utilization.
Continuous, anaerobic fermentations of D-xylose were performed by Actinobacillus succinogenes 130Z in a custom, biofilm reactor at dilution rates of 0.05, 0.10 and 0.30 h(-1). Succinic acid yields on xylose (0.55-0.68 g g(-1)), titres (10.9-29.4 g L-1) and productivities (1.5-3.4 g L-1 h(-1)) were lower than those of a previous study on glucose, but product ratios (succinic acid/acetic acid = 3.0-5.0 g g(-1)) and carbohydrate consumption rates were similar. Also, mass balance closures on xylose were up to 18.2 \% lower than those on glucose. A modified HPLC method revealed pyruvic acid excretion at appreciable concentrations (1.2-1.9 g L-1) which improved the mass balance closure by up to 16.8 \%. Furthermore, redox balances based on the accounted xylose consumed and the excreted metabolites, indicated an overproduction of reducing power. The oxidative pentose phosphate pathway was shown to be a plausible source of the additional reducing power.
The biotechnology industry demands raw materials to prepare growth media for fermentative processes. These media contain a carbon source which can be obtained from potato, an abundant source of starch. This work deals with the modelling of the enzymatic hydrolysis of potato using alpha-amylase and glucoamylase. Several strategies were evaluated, including the use of those enzymes alone, in a mixture and under different conditions of temperature, time and substrate concentration. Using alpha-amylase alone or glucoamylase alone, both enzymes reached the same hydrolysis yield (0.42 g/g). The hydrolysis using a mixture of both enzymes allowed obtaining hydrolysates with reducing sugar concentrations up to 14.1 g/L at 70 degrees C. In this case, the yield of hydrolysis was increased up to 0.82 g/g. Considering the important effect and interactions of time and temperature, a statistical Box-Behnken design was conducted including substrate concentration, time and temperature as operational variables and reducing sugar concentration released as dependent variable. The conditions to obtain the maximum response were 6\% DM of substrate concentration, 68 degrees C and 180 min, where 32.62 g/L of reducing sugar concentration was predicted. Verification experiments gave a mean value of 33.57 g/L, confirming the accuracy of the model. (C) 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.
Litchi tree is planted in several countries of the world for its juicy fruit. For the estimated total annual global litchi production of similar to 2.7 million tons, around similar to 0.54 million tons of seeds as well as a sizeable amount of skin are generated as waste. This renewable waste biomass can be effectively used as the feedstock for recovering energy and obtaining several value-added products. In the present work, the fuel and thermochemical characteristics and thermal degradation behavior of acid- and alkali-treated litchi seed biomass were systematically investigated and compared for the first time. The average and maximum rate of mass losses, peak temperature and pyrolysis factor had been evaluated to assess the reactivity of the treated biomass. It had been observed that acid and alkali treatments improved the higher heating value and changed the thermal degradation behavior. The thermogravimetric (TG)/differential thermogravimetric analysis (DTG) data obtained at the heating rates of 20, 25 and 30 degrees C min(-1) were used to evaluate the kinetic and thermodynamic parameters using iso-conversional models of Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Tang and Starink. The Criado method had been used to elucidate the prevailing thermal degradation reaction mechanisms at different fractional conversions. The average activation energy of the acid-treated biomass increased, and that of the alkali-treated biomass decreased compared to that of the untreated biomass. {[
Empty fruit bunch oil palm (EFBOP) is one of the byproducts after oil palm fruitlet is removed in oil palm processing and is considered as waste. In this study, EFBOP was converted to biochar (BC-EFBOP) at 350-700 degrees C, with an overarching aim of determining the feasibility of adsorptive removal of manganese (a second dominant element in acid mine drainage) from water. Results showed that with increasing temperature, the BC-EFBOP yield decreased from 44.34\% to 26.74\%, along with the H/C (0.89\%-0.29\%) and O/C ratios (0.38\%-0.23\%), and the carbon content increased (62.7\%-73.93\%). As evidenced by Fourier Transform InfraRed spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS), abundant oxygen-containing surface functional groups such as hydroxyl (-OH), carboxyl (-COOH), and ether (C-O-C) were retained, and aromatic C--C groups were largely generated in the biochar. Pyrolysed biochar at 350 degrees C (BC350), with the least surface area (0.5 m2 g- 1), exhibited the highest Mn2+ adsorption capacity (8.2 mg g- 1), whereas for BC700, with the largest surface area (2.19 m2 g- 1), had the lowest capacity for Mn2+ (1.2 mg g- 1). Regardless of the temperature, solution pH of 5 was found to be optimal for Mn2+ removal from water. The Langmuir isotherm model best described the equilibrium adsorption data with a maximum adsorption capacity of 1.2-8.2 mg g- 1 for initial concentrations of 5-250 mg L-1, whereas the adsorption kinetics followed the pseudo-second-order model. There was nearly four-fold in-crease in Mn2+ ions removal with increased biochar dosage (0.05-0.5 g), at initial Mn2+ concentration of 100 mg L-1. The study showed that a low-cost, environmentally friendly BC-EFBOP with optimal surface chemistry could potentially remediate Mn2+ ions from aqueous media. However, a proper cost-benefit and techno-economic analysis is needed prior to potential pilot scale studies.
The present study aims to assess the impact of the type of yeast consortium used during bioethanol production from starchy biowastes and to determine the optimal fermentation conditions for enhanced bioethanol production. Three different yeast strains, Saccharomyces cerevisiae, Pichia barkeri, and Candida intermedia were used in mono- and co-cultures with pretreated waste-rice as substrate. The optimization of fermentation conditions i.e., fermentation time, temperature, pH, and inoculum size, was investigated in small-scale batch cultures and subsequently, the optimal conditions were applied for scaling-up and validation of the process in a 7-L fermenter. It was shown that co-culturing of yeasts either in couples or triples significantly enhanced the fermentation efficiency of the process, with ethanol yield reaching 167.80 +/- 0.49 g/kg of biowaste during experiments in the fermenter.
In recent years, the construction sector has significantly increased demand for new building materials that can reduce environmental impact and promote sustainable design strategies. In this context, the use of earth for construction purposes has received increasing attention in the last decade owing to its low environmental impact, local availability, and recyclability. The literature survey indicates that the incorporation of waste materials in the production of unfired earth bricks holds significant potential to partly substitute earth by satisfying specific requirements. Additionally, utilizing these waste materials for the development of unfired earth bricks provides a solution that conserves natural resources, reduces energy consumption, and contributes to efficient waste management. The aim of this paper is to present an overview of recent research focusing on the recycling of various types of waste into eco-friendly unfired earth bricks. Also, the effect of the incorporation of waste materials on the thermal and mechanical properties of unfired clay bricks is reviewed. The most common results, organized based on the type of additive (industrial or agricultural waste), are shown and discussed.
Lignin and Irganox 1010, a hindered phenol antioxidant, are compared as a primary stabilizer in formulations for polypropylene ( PP) by exposition to accelerated aging. The concentration of lignin was adjusted to match the concentration of hindered phenolic groups of the commercial stabilizer. Upon aging, lignin formulation retains the initial mechanical properties longer than the formulation with Irganox 1010. The ratio of the areas of the carbonyl and the hydroxyl infrared absorption bands is proposed as a method to evaluate the photodegradation process. In this aspect, the formulation with lignin also presents better results than the formulation with Irganox 1010. There are two hypotheses for the best performance of lignin in the studied conditions: lower leaching of lignin, due to its crosslinked nature, and leaching of low molar mass products of Irganox 1010 hydrolysis. These results indicate lignin, from the Kraft process of Eucalyptus wood, as a promising green substituent to synthetic hindered phenol stabilizers. (C) 2016 Wiley Periodicals, Inc.
A 25 kW(th), fixed, perforated bed, downdraft gasifier was used to investigate and compare its performance for using corn cob (CC) and coconut shell (CS) - a proven fuel for gasification as feedstocks. Air was used as a gasifying medium and had been administered inside the gasifier reaction zone (just above the throat) through four equally spaced conduits in forced circulation mode. Gas composition, higher heating value (HHV) of gas, specific gas generation (SGG), and gasification efficiencies had been compared for CC and CS by varying the equivalence ratios (ERs) from 0.1-0.45. HHV of gas generated upon the gasification was inferred to be maximum at an ER of 0.3 while using CC (4.578 MJ/m(3)) and that of 0.35 for using CS (4.229 MJ/m(3)) as feedstocks. SGG - associated with maximum HHV of gas - was observed to be 2.12 m(3)/kg and 3.05 m(3)/kg for CC and CS, respectively. Optimal cold gas efficiency was obtained at the best operating point, i.e., at ERs of 0.3 and 0.35 for CC (62.83\%) and CS (72.74\%) gasification, respectively. Tar contents of 1.3 g/m(3)and 0.62 g/m(3)and particulate matter contents of 0.355 g/m(3)and 0.215 g/m(3)were quantified for the producer gas generated from CC and CS gasification, respectively.
Eucalyptus leaves were investigated as a source for the isolation of xylanase producing microorganisms. A total of 37 isolates were obtained after a series of enrichment steps. Seven of the isolates were xylanase positive in an agar screening experiment and were further analyzed in liquid media with beechwood xylan as carbon source. A yeast identified as Pseudozyma sp. showed the highest xylanase activity in tested conditions. Afterwards, different lignocellulosic residues were studied as substrates for xylanase production by this strain and the best results were obtained with corncob. Yeast's xylanase with a molecular weight of 19.9 kDa showed the maximum activity at pH 4.8 and 50 degrees C. Thermostability was observed at 30 degrees C with a 60\% activity retention after 10 days. By the hydrolytic activity of the enzyme was characterized as an endoxylanase, similar as the ones found in family GH 10, from the products obtained by beechwood xylan hydrolysis.
The ethanol production process employing lignocellulosic material (second generation ethanol - 2G) is one of the remarkable proposals for the worldwide energetic security. Currently, there is a significant technical-scientific effort in order to obtain sustainable alternative routes for the production of 2G ethanol. The thermodynamic property exergy can be applied for the execution of the energetic analysis of this type of system. The analysis of the exergetic content indicates the economic value associated to the process, since it is characterized as the potential to execute work. In this sense, the exergetic analysis is applied to evaluate alternative technologies for the sustainable development, being a resource of increasing use in the literature. However, there is still a reduced amount of review articles, particularly in Brazilian literature, destined to present the application of this type of analysis to 2G ethanol production. Therefore, this article aims to exhibit some fundamental concepts about this technique, as well as indicators and analysis methods based on exergy. Besides that, applications of the technique to 2G ethanol production processes are presented, in order to highlight the applicability of the thermodynamic evaluation, exergetic analyses and methods and main diagnoses obtained by means of this technique.
Present investigation explores the potential of defatted rice bran (DRB) serving as sole carbon source and partial nitrogen source to support Lactococcus lactis growth and nisin production. To retain the nutrients in DRB, especially protein fractions, thermal pretreatment followed by enzymatic hydrolysis without washing step was applied for saccharification. A maximum of 45.64 g reducing sugar mainly containing 30.26 g glucose and 5.66 g xylose from 100 g DRB was attained in hydrolysates of DRB (HD). A novel strategy of xylR (xylose transcriptional regulator) overexpression followed by evolutionary engineering was proposed, which significantly increased the capacity of L. lactis to metabolize xylose. Subsequently, RTPCR results indicated that xylR overexpression stimulated expression of xylose assimilation genes synergistically with exposure to xylose. In HD medium, the highest nisin titer of the engineered strain FEXR was 3824.53 IU/mL, which was 1.37 times of that in sucrose medium by the original strain F44. (C) 2017 Elsevier Ltd. All rights reserved.
The effects of physicochemical pre-treatment were evaluated on hydrogen (H2) production and organic acids from hydrolyzed potato peel. Central composite design (CCD) and response surface methodology (RSM) were used to evaluate the effects of different substrate concentrations on a wet basis (38.8-81.2 g.L-1) and hydrolyser ratios (6M NaOH and 30\% HCl: 1.6-4.4\% v.v-1; and H2SO4: 2.2-7.8\% v.v-1). The experiments were conducted in batch reactors at 37 degrees C, using a heat-treated microbial consortium. The maximum H2 production potential (P), lag phase (lambda), and maximum H2 production rate (Rm) were evaluated for untreated and pre-treated potato peel waste. H2 production was positively influenced under hydrolyzed substrate concentrations >= 75 g.L-1 in the three CCDs performed. Only the increase in the H2SO4 proportions (>= 5\% v.v-1) had a negative influence on H2 production. Increasing the 30\% HCl and 6M NaOH proportions did not significantly influence the cumulative H2 production. The highest hydrogen production was obtained after alkaline pre-treatment by dark fermentation (P: 762.09 mL H2.L-1; lambda: 14.56 h; Rm: 38.39 mL H2.L-1.h-1). Based on the CCD and RSM, the highest H2 production (1060.10 mL H2.L-1) was observed with 81.2 g.L-1 hydrolyzed potato peel with 3.0\% v.v-1 of 6M NaOH. The highest yield liquid metabolites were acetic (513.70 mg. g-1 COD) and butyric acids (491.90 mg. g-1 COD).
1,3-BD production process from lignin consisting of four unit operations such as gasification, dimethyl ether (DME) synthesis, n-butene synthesis, and isomerization/dehydrogenation, was simulated. This process could be designed as a renewable energy system that can not only produce 1,3-BD but also self-supply almost all the heat and power for the operation. The balance of payment (BP), which is the income incurred from processing a unit weight of lignin, was employed as the economic efficiency of the process. The effect of the reaction conditions in the DME to n-butene synthesis step (the third step) on the BP was investigated. Since few catalysts have been reported for synthesizing n-butene from DME, realistic reaction conditions and catalytic performance were set. An increase in the DME content of the feed gas and a decrease in the reaction pressure led to an increase in the n-butene yield and a decrease in the power, followed by an increase in the 1,3-BD yield and BP. Considering the expected power selling price after the termination of the Feed-in-Tariff scheme, the 1,3-BD production process could have comparable BPs with gasification power generation as a representative competitive process. (C) 2020 Elsevier Ltd. All rights reserved.
Hazardous wastes produced from different industrial activities mainly contribute to serious environmental problems, notably their negative impact on the human health. Therefore, there is a great need to implement an innovative protocol for the safe disposal of these wastes in the production of widely-used materials. This study focused on the sustainable consumption of hazardous lead-bearing and dry-bed sewage sludges (LBS and DBS, respectively) in the production of lightweight bricks using alkali-activation process in which cement kiln dust (CKD) used as alkali-rich-waste. Very simple procedures were carried out to prepare the hardened bricks comprising wet mixing sludge-CKD blend and humidity-curing at 23 +/- 2 degrees C for 24 h. The performance of the prepared bricks mainly depends on CKD content, chemical composition and physical characteristics of sludges, and thermal treatment. The increase of CKD content (up to 50 wt \%) within LBS-CKD mixtures leads to a significant improvement in the mechanical properties of the produced bricks; whereas, it demonstrated a marginal effect on DBS-CKD set. The main reason behind too low compressive strength (<= 1.5 MPa) of DBS-CKD is the low pozzolanic activity caused by the high organic matter content (similar to 42 wt \%) within DBS composition. Nevertheless, all DBS-CKD bricks recorded the lowest bulk density values ranging from 0.92 to 0.99 g/cm(3) at 28-days of humidity curing. The full replacement of untreated sludges with thermally-treated one, yields hardened bricks with higher bulk density and compressive strength. Achieving eco-sustainability, low energy demand, and cost minimization, we recommend to use the LBS-CKD (50-50 wt \%) mixture in the fabrication of lightweight bricks as it showed desirable mechanical properties, relatively low bulk density, low drying shrinkage, and low Pb-concentration in leachate. (C) 2020 Elsevier Ltd. All rights reserved.
Direct hydrolysis of a towel to glucose was investigated using steam explosion and microwave-assisted treatment to find effective uses for cotton waste. The maximum glucose yield by direct hydrolysis (based on an untreated towel) was 18.8\%, obtained at a steam pressure of 5.5MPa (at 271 degrees C) and steaming time of 5min using steam explosion. For the microwave-assisted treatment, with a 1.0 (w/w)\% sulfuric acid catalyst, the maximum glucose yield by direct hydrolysis was 28.9\%, obtained at a microwave heating temperature of 200 degrees C for 7min. The maximum total glucose yield (from both direct hydrolysis and enzymatic hydrolysis of treated residue) was 78.0\%, attained at a microwave heating temperature of 200 degrees C for 7min with 0.5 (w/w)\% sulfuric acid catalyst. Furthermore, the maximum total glucose and valuable water soluble chemicals (cellobiose, 5-hydroxymethylfurfural, formic acid, and levulinic acid), 94.1\%, were achieved at heating temperature of 200 degrees C for 10min with 0.5 (w/w)\% sulfuric acid catalyst. Finally, ethanol, 84.5\% of conversion rate, could be produced using supernatant (it contained glucose) and microwave treated residue (200 degrees C for 7min with 0.25 (w/w)\% sulfuric acid catalyst) as carbon source for Saccharomyces cerevisiae with less fermentation inhibition.
Production of bioethanol from various lignocellulosic biomass through enzymatic hydrolysis is considered as a promising approach to fulfill the global energy demand. In addition to overcoming the worldwide energy crisis, it also plays an important role in the management of lignocellulosic waste. We have synthesized iron oxide nanoparticles (magnetic nanoparticles-MNPs) using cell filtrate of fungus, Alternaria alternata. The synthesis of MNPs was initially confirmed by the visual observation followed by characterization using different analytical techniques. The NTA and TEM analysis showed the average size of 47 and 55 nm respectively. XRD analysis confirmed the FCC structure of nanoparticles and zeta potential for MNPs was - 7.06 mV, which indicated the stability of nanoparticles. Further, comparative evaluation of enzymatic hydrolysis of lignocellulosic biomass (sugarcane bagasse) using free and immobilized cellulase on MNPs at different temperatures was studied. The results obtained demonstrated that, in first cycle of hydrolysis, free enzyme was more efficient which showed about 78\% conversion of cellulose to glucose at 40 A degrees C after 24 h, whereas in case of immobilized enzyme it was found to be 72\%. Moreover, immobilized cellulase was recovered by applying magnetic field and reused up to third cycle of hydrolysis. In second and third cycle, rate of conversion of cellulose to glucose was found to be 68 and 52\% respectively. These findings suggest that immobilization of cellulase on MNPs facilitate the easy recovery and their reuse for more than one cycle of hydrolysis, thereby making the process economically viable. Further, optimization and modification of certain conditions will be helpful to increase the efficiency of immobilized enzyme.
The possibilities of complete utilization of rapeseed meal to produce lipophilic phenolic compounds, protein, and monosugars were evaluated extensively in this work. Advanced techniques including NMR and MS were employed for confirming the occurrence of the proposed reaction structurally. Lipophilization of the major phenolic compound in rapeseed meal, sinapine, by transesterification reaction was achieved in a solvent-free system with optimal conditions of 10 mg NaOH/g meal, 70 degrees C, 15 mL methanol/g meal, and 15 min. Sinapate alkyl esters yields were decreased gradually with longer chain alcohols. However, the purity of the targeted compounds in corresponding alcohols was improved due to low solubilities of the other polar compounds. After sinapate alkyl esters production, the solid residue was soaked in NaOH solution at room temperature for protein extraction and 50 mg protein/g meal with protein content of 77\% was obtained. The above two procedures played roles as pretreatments of the carbohydrate. Hexose yield of 67\% was reached without any other pretreatments. This work suggests the big possibilities of producing high value products from rapeseed meal in a concordant manner.
A bio-solution of natural organic enzyme-7F (NOE-7F) is used to pretreat bamboo, with emphasis on the influence the pretreatment upon the structure, reactivity, and torrefaction of the biomass. Two different operating modes accompanied by five different soaking durations are considered. In Mode 1 the bamboo is ground followed by pretreated by the bio-solution, and an inverse procedure is used in Mode 2. The results indicate that, with the operation of Mode 1, NOE-7F removes hemicellulose in the bamboo significantly, thereby improving the homogeneity of the biomass. This pretreated bamboo may be feasible for enzymatic hydrolysis to produce bioethanol. The penetration of the bio-solution into block bamboo becomes the controlling mechanism under Mode 2 operation, and therefore relatively less hemicellulose is consumed from Mode 2. The ignition and burnout temperatures of the pretreated bamboo are higher than those of the raw bamboo, revealing the lower reactivity and higher storage safety of the former. The atomic H/C and 0/C ratios as well as the calorific value of the bamboo are insensitive to the pretreatments, whereas the crystalline structure of cellulose is affected by the bio-solution to a certain extent, regardless of Mode 1 or Mode 2 operation. This suggests that torrefaction is required if the pretreated bamboo is employed as a fuel. The pretreated bamboo with Mode 2 is more suitable for torrefaction because of higher torrefaction severity.(C) 2016 Elsevier Ltd. All rights reserved.
This study analyzes the feasibility of using biomass combustion ash waste (rice husk or wood ash from boards) as secondary raw materials in the manufacture of clay bricks. The ash was characterized using particle size distribution analysis, chemical composition analysis by X-ray diffraction (XRD) and X-ray fluorescence (XRF), thermal analysis, elemental analysis, and scanning electron microscopy (SEM). Either rice husk ash or wood ash was used to replace different amounts (10-30 wt\%) of clay in brick manufacture. Brick samples were formed by compression at 54.5 MPa and fired at temperatures of 900 or 1000 degrees C for 4 h, at a heating rate of 3 degrees C/min. The bricks' properties were compared to conventional products containing only clay and prepared following standard procedures. The bricks' technological properties depended on type and amount of ash used, and firing temperature. The results showed small variations due to firing temperature. Firing at 1000 degrees C achieved greater densification and thus lower water absorption and higher compressive strength firing at 900 degrees C produced higher porosity, which reduced compressive strength. Based on the results, 1000 degrees C was selected as the optimal firing temperature; and 10 wt\% rice husk ash and 20 wt\% wood ash as the optima amounts of biomass ash waste. Moreover, the bricks containing wood ash showed properties similar to the control bricks containing only clay and improved thermal conductivity. Finally, the bricks containing 10 wt\% rice husk ash and 30 wt\% wood ash fulfilled standard requirements for clay masonry units.
Biosynthesis of xylitol using the yeast Debaryomyces hansenii NRRL Y-7426 was carried out using distilled grape marc (DGM) hemicellulosic hydrolysates directly concentrated by vacuum evaporation or after detoxification with activated charcoal. The effect of nutrient supplementation with vinasses, corn steep liquor (CSL) or commercial nutrients was explored. Using crude concentrated hemicellulosic hydrolysates, the maximum xylitol concentration, 11.3 g/L, was achieved after 172 hr (Q(xylitol) - 0.066 g/L-hr; Y-xylitol/SC - 0.21 g/g); meanwhile, using detoxified concentrated hydrolysates, the concentration increased up to 19.7 g/L after 72 hr (Q(xylitol) = 0.274 g/L-hr; Y-xylitol/SC = 0.38 g/g). On the other hand, using crude or detoxified hydrolysates, the xylose-to-xylitol bioconversion was strongly affected by the addition of nutrients, suggesting that these hydrolysates present essential nutrients favouring the growth of D. hansenii.
Fibers from passion fruit stalks were first recovered with a pulping and bleaching process. Two mechanical treatments were further applied to the fibers, homogenization (with and without ultrasound), and blender application. The effect of those treatments on fibers was evaluated. The chemical composition of the different stages of fibers undergoing treatment were measured according to TAPPI standards and were also analyzed by SEM, FTIR, and XRD. Trypsin was immobilized by adsorption and by covalent binding. The biocatalyst support-trypsin was evaluated in terms of immobilization yield, retention, and enzymatic activity. The experimental results demonstrated that the final cellulose concentration in the fibers was 44 \% higher than that in the raw stalks. The cellulose nanofibers obtained by homogenization presented a size distribution between 20-200 nm, and the application of ultrasound did not show a significant effect on size (between 50 to 300 nm). Trypsin immobilized using glycidol presented an immobilization yield of 67 \% and presented higher retention and enzymatic activity (1.17 +/- 0.05 U/mg protein and 44.0 +/- 2.0 \%, respectively). These results show that passion fruit stalks can be successfully used as a source of cellulose nanofibers and also can be used as carriers for the immobilization of trypsin.
In this study, the removal efficiencies of bio-based rigid polyurethane foams ({''
Pyrolytic conversion of Erythrina indica under inert conditions at 600 degrees C and 1 bar pressure resulted in 26.873 wt. \% of bio-oil, 42.870 wt. \% of biochar, and 30.257 wt. \% of non-condensable gases. The fuel phase separation was performed at 10\%, 20\%, 30\%, and 40\% (on volume basis) of a solvent-to-bio-oil ratio using dichloromethane and n-hexane, which depicted significant improvement in its physiochemical properties. However, the fuel phase obtained using n-hexane had better physiochemical properties than that obtained by dichloromethane, indicating n-hexane as a better solvent. The fuel phase extraction utilizing 30 and 40 vol. \% of n-hexane showed that they were close to regular gasoline in terms of density, viscosity, and calorific value, which turned out to be the best accomplishment of this work. The calorific value of the fuel phases, extracted by dichloromethane and n-hexane, respectively, were discovered to range between 14.360 and 23.670 MJ/kg and 26.290 and 39.730 MJ/kg. Gross calorific values of corresponding biochar and the non-condensable gases were found to be 28.030 MJ/kg and 14.486 MJ/N m(3), respectively. The composition of non-condensable gases revealed that 16.822 vol. \% of hydrogen is present, and thus, it can be a good source of green hydrogen. Biochar produced from the pyrolytic conversion of E. indica is equivalent to conventional coal based on comparison of their physical, fuel, and other relevant properties.
Fenton pretreatment is known as a green and mild approach, but it is usually time-consuming and inefficient in promoting lignocellulose enzymatic hydrolysis. Here we demonstrate that thioglycolic acid (TA) significantly accelerates Fenton pretreatment (FP) of corn stover (CS) and improves enzymatic hydrolysis of cellulose and xylan. The results showed that the reducing sugar yield of CS reached 77.0\% with TA-assisted FP in only 16 h, while it was only 34.1\% and 38.0\% with FP alone in 16 h and 72 h, respectively. Via examination of the changes of composition, physical and chemical characteristics of CS before and after pretreatment, it was found that TA assisted FP greatly improved the removal of hemicellulose and lignin, resulting in increment of the pore volume, pore size and cellulose exposure of CS substrate, which together promoted the enzymatic saccharification of CS.
This work deals with experimental research about acoustic panels made of agricultural waste to be used as ceiling tiles, providing a sustainable and environmentally friendly alternative to traditional building materials. The raw materials used in this work were rice husk, vine pruning residues, cork (white cork, virgin cork, and expanded cork), and prickly pear. All of them were bonded with a water-based acrylic resin in different proportions. The obtained panels were mechanically, thermally and acoustically tested. The flexural and the dynamic modulus of elasticity, as well as other important physical properties, such as open porosity, tortuosity or flow resistivity, and thermal conductivity, were obtained. The sound absorption coefficient of the biocomposites was experimentally measured, using an impedance tube, and modeled, using the Zwikker and Kosten model, over the frequency range from 200 Hz to 6400 Hz. The results showed values of sound absorption coefficients close to 0.80 and acceptable flexural strength for their use as suspended ceiling tiles. Therefore, these new categories of biocomposites provide sustainable bio-based materials that can be an alternative to the traditional acoustic ceiling panels, mainly composed of synthetic fibers or foams and petroleum-based resins. (C) 2022 Elsevier Ltd. All rights reserved.
beta-Glucosidases show great potential as catalysts for various biotechnology processes including biomass hydrolysis for bioethanol production. In this study, response surface methodology was used to evaluate the effect of some variables on beta-glucosidase production by Penicillium verruculosum using passion fruit peel as substrate, and on hydrolysis of this process residue with P. verruculosum crude extract, by applying a full factorial central composite design. Process optimization resulted in a 5.7 fold increase in beta-glucosidase activity. The enzymes were more active at 65 degrees C, pH 4.5, remaining stable at 55 and 60 degrees C and over a broad pH range. P. verruculosum crude extract hydrolyzed passion fruit peel with glucose yield of 45.54\%. This article provides, for the first time, the production of remarkable yields of beta-glucosidase and the achievement of expressive levels of glucose through the use of passion fruit peel, an abundant and inexpensive agro-industrial residue. (C) 2014 Elsevier Ltd. All rights reserved.
The use of alternative materials for environmental decontamination has been intensively studied. In this study, the capacity of banana peels treated with sodium hydroxide (NaOH), hydrochloric acid (HCl), and phosphoric acid (H3PO4) to adsorb Pb (II) was evaluated. The physical and chemical changes on the banana peels after chemical treatment were evaluated by infrared spectroscopy and scanning electron microscopy. Batch adsorption experiments were carried out as a function of pH, time, metal concentration, and temperature; desorption tests were also performed. Pb (II) concentrations were determined by flame atomic absorption spectrometry. An increase in the adsorption capacity of the modified and natural peels was observed in the pH range of 3-5, and pH 5 was adopted for further experiments. The adsorption system reached equilibrium in 300min, and its kinetics followed the pseudo-second-order equation. From adsorption isotherms, it was observed considerable enhance on adsorption capacity of banana peels, especially with treated with NaOH. Besides, the negative Gibbs free energy variation values showed that the Pb (II) adsorption was spontaneous. Moreover, the improvement in the Pb (II) desorption for the modified peels was observed, indicating that the proposed material can be reutilized.
This article describes the preparation and characterization of the cellulose/hydrated zirconium oxide composites prepared by conventional precipitation (PC) and homogeneous solution precipitation (PSH) methods. The composite obtained by the PC method was prepared by using an ammonia solution as the precipitating agent, while the composite obtained by the PSH method was prepared by using area as the precipitating agent. The adsorption of dichromate ions on the composites was studied using factorial design 2(3). The variables were: initial concentration, agitation time and mass of the composite. The data obtained agree better for the composite obtained by the PC method.
In recent years, the need for clean, viable and sustainable source of alternative fuel is on the rampage in the global space due to the challenges posed by human factors including fossil induced emissions, fuel shortage and its ever-rising prices. These challenges are the major reason to utilize alternative source of energy such as lignocellulosic biomass as domestic and industrial feedstock. However, biomass in their raw form is problematic for application, hence, a dire need for torrefaction pre-treatment is required. The torrefaction option could ameliorate biomass limitations such as low heating value, high volatile matter, low bulk density, hygroscopic and combustion behaviour, low energy density and its fibrous nature. The torrefied product in powder form could cause air pollution and make utilization, handling, transportation, and storage challenging, hence, densification into product of higher density briquettes. This paper therefore provides an overview on the performance of torrefied briquettes from agricultural wastes. The review discusses biomass and their constituents, torrefaction pre-treatment, briquetting of torrefied biomass, the parameters influencing the quality, behaviour and applications of torrefied briquettes, and way forward in the briquetting sector in the developing world.
Novel developments in the fiber sector require additional investigation of their behaviour during the production process. In the core step of the viscose process, cellulose fibres are regenerated in an acidic spinning bath. To investigate the influence of hemicellulose content and temperature on the kinetics of fiber degradation, standard and hemicellose-enriched fibers were treated in the acidic standard spinning bath for time periods up to 292 h. Viscose samples of different hemicellulose content were prepared under standardized conditions and the never dried fibres were subjected to long term degradation in the standard spinning bath at 40, 50 and 60 A degrees C. The changes in the degree of polymerization (DP), molar mass distribution, hemicellulose and the generation of the total organic carbon in the spinning bath were monitored. Further, the changes in crystallinity and the level-off-DP of the fibers were determined to improve the accuracy of the existing degradation model. Changes in morphology of the fibers were monitored by optical microscopy and scanning electron microscopy.
The enhancement of lignocellulose hydrolysis using enzyme complexes requires an efficient pretreatment process to obtain susceptible conditions for the enzyme attack. This study focuses on removing a major part of the lignin layer from kenaf (Hibiscus cannabinus) while simultaneously maintaining most of the hemicellulose. A two-stage pretreatment process is adopted using calcium hydroxide, Ca(OH)(2), and peracetic acid, PPA, to break the recalcitrant lignin layer from other structural polysaccharides. An experimental screening of several pretreatment chemicals, concentrations, temperatures and solid-liquid ratios enabled the production of an optimally designed pretreatment process for kenaf. Our results showed that the pretreatment process has provide 59.25\% lignin removal while maintaining 87.72\% and 96.17\% hemicellulose and cellulose, respectively, using 1 g of Ca(OH)(2)/L and a 8:1 (mL:g) ratio of liquid-Ca(OH)(2) at 50 degrees C for 1.5 h followed by 20\% peracetic acid pretreatment at 75 degrees C for 2 h. These results validate this mild approach for aiding future enzymatic hydrolysis. (C) 2013 Elsevier Ltd. All rights reserved.
In this era of industrial revolution and diminishing petroleum reserves, alternative options (woody biomass) for building next-generation fuels need to be critically explored. Here, process engineering aspects of 5-hydroxymethylfurfural (5-HMF) from Bambusa bamboo in ionic liquid ({[
Lignocellulosic and algal biomass feedstocks are the most plentiful and cost-effective renewable sources of biofuels (sugar, bioethanol, biodiesel, and bio-oil), value-added chemicals (organic compounds), and advanced materials (hydrogels and composites). The lignin, cellulose, and hemicellulose complex's recalcitrance, which leads to ineffective conversion into valuable compounds, is one of the most significant challenges in biomass valorization. Some ionic liquids (ILs) have been shown to be efficient decomposers of lignocellulosic and algal biomass. In reality, ILs offer a unique green alternative compared to harmful volatile organic solvents and severe process conditions. Enhanced productivity in the conversion of biomass feedstocks could result from advancements in IL-based pretreatment technologies. The capability of the different types of ILs for conversion, as well as the impact of different properties and operating parameters, are comprehensively reviewed and discussed in this paper. The known methods for the dissolution of three main components of lignocellulosic and algal biomass with ILs are also described. Furthermore, the challenges to be addressed when utilizing IL for biomass pretreatment and processing on a commercial scale are highlighted. The significant promise of ionic liquids for this objective is anticipated to stimulate research and lead to considerable technological advancements in this field.
Apple pomace was used as a sole raw material for single cell oil (SCO) production by the oleaginous yeast Rhodosporidium toruloides DSM 4444. Preliminary studies with glucose medium revealed 100 mL of working volume in 500 mL Erlenmeyer flask as the most efficient in terms of lipid content. Thus, apple pomace hydrolysate was tested in six different conditions using 100 mL medium. The detoxified hydrolysate without chemical supplement (D medium) was found to be the most viable medium by 47.5 +/- 2.47\% lipid on dry cell basis (w/w). Apple pomace hydrolysate was also proven effective for SCO productions in bench-top fermenter (1 L working volume) under controlled temperature (25 degrees C), pH (5.0), and aeration (1vvm) by 40.1 +/- 5.51\% (w/w) lipid content. The same medium resulted in 50.9\% (w/w) lipid on a dry cell basis in 30 L industrial-type bioreactor with 10 L of working volume, without exact control of temperature and pH. The results confirm that apple pomace is a prosperous raw material for SCO production in flask and fermenter scales. {[
The isolation of nanocellulose materials by means of enzymatic hydrolysis offers advantages in terms of their properties and operational conditions, but there is still a lack of enzymatic cocktails specifically designed for this application. The present work investigates the use of a thermostable endoglucanase-rich enzymatic cocktail from Myceliophthora thermophila for nanocellulose production. An initial set of experiments was conducted to determine the optimal conditions for enzyme production under solid-state cultivation in small-scale polypropylene plastic bags. A full factorial experimental design was used as a statistical tool to evaluate the effects of the solid substrate and moisture content on the production of endoglucanase and beta-glucosidase. Solid-state cultivations in a multilayer packed-bed bioreactor were then carried out under the selected conditions to obtain a larger volume of an enzymatic extract with high endoglucanase selectivity, given by the ratio of endoglucanase (203 +/- 6 U/g-substrate) to beta-glucosidase activity (1.6 +/- 0.1 U/g-substrate). The enzymatic hydrolysis of eucalyptus cellulose pulp at different temperatures, with this endoglucanase-rich cocktail at a loading of 10 mg-protein/g-pulp, resulted in higher glucose release (11 +/- 2 g-glucose/L) at 60 degrees C, with 61 +/- 9\% cellulose conversion and 16.2\% nanocellulose yield. The isolated nanomaterial with average diameter of 36.65 nm and length of 156.63 nm, presented a crystallinity index of 77.4\% and thermal stability temperature of 316 degrees C. These results show the potential to isolate nanocellulose using a thermostable endoglucanase-rich enzymatic cocktail produced locally by solid-state cultivation in a packed-bed bioreactor, in accordance to the biorefinery concept.
Many physical, chemical, and/or enzymatic treatments have been used to open the structure of lignocellulosic biomass, separate its components and obtain cellulose. The alkaline-bleaching treatment is most preferred in terms of reagent availability. In terms of cellulose yield and quality, however, there are inconsistencies with the alkaline-bleaching treatment. Similarly, the optimum conditions for carboxymethylcellulose (CMC) synthesis from cellulose mercerization and etherification are vague. This review paper investigates and compares the various conditions applied in CMC synthesis and recommends efficient processes and optimal conditions for increasing CMC yield and quality. Recommended mercerization parameters are 25-30\% (w/v) NaOH, 1-1.5 h and 25-28 degrees C. Recommended etherification parameters are 1.2 g chloroacetic acid (CAA) or sodium chloroacetate (SCA)/g cellulose, 3-3.5 h and 50-55 degrees C. The source material and extraction process determines the quality of the cellulose produced. Therefore, identifying the most efficient methods and underlying conditions for various cellulose sources is important. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.
Background: The development of technological routes to convert lignocellulosic biomass to liquid fuels requires an in-depth understanding of the cell wall architecture of substrates. Essential pretreatment processes are conducted to reduce biomass recalcitrance and usually increase the reactive surface area. Quantitative three-dimensional information about both bulk and surface structural features of substrates needs to be obtained to expand our knowledge of substrates. In this work, phase-contrast tomography (PCT) was used to gather information about the structure of a model lignocellulosic biomass (piassava fibers). Results: The three-dimensional cellular organization of piassava fibers was characterized by PCT using synchrotron radiation. This technique enabled important physical features that describe the substrate piassava fibers to be visualized and quantified. The external surface area of a fiber and internal surface area of the pores in a fiber could be determined separately. More than 96\% of the overall surface area available to enzymes was in the bulk substrate. The pore surface area and length exhibited a positive linear relationship, where the slope of this relationship depended on the plant tissue. Conclusions: We demonstrated that PCT is a powerful tool for the three-dimensional characterization of the cell wall features related to biomass recalcitrance. Original and relevant quantitative information about the structural features of the analyzed material were obtained. The data obtained by PCT can be used to improve processing routes to efficiently convert biomass feedstock into sugars.
Hydrochars derived from hickory wood and peanut hull through hydrothermal carbonization were activated with H3PO4 and KOH to improve their performance as a volatile organic compound (VOC) adsorbent. Polar acetone and nonpolar cyclohexane were used as representative VOCs. The VOC adsorptive capacities of the activated hydrochars (50.57-159.66 mg.g(-1)) were greater than that of the nonactivated hydrochars (15.98-25.36 mg.g(-1)), which was mainly caused by the enlargement of surface area. The significant linear correlation (R-2 = 0.984 on acetone, and R-2 = 0.869 on cyclohexane) between BET surface areas of hydrochars and their VOC adsorption capacities, together with the obvious adsorption exothermal peak of differential scanning calorimetry curve confirmed physical adsorption as the dominating mechanism. Finally, the reusability of activated hydrochar was tested on H3PO4 activated hickory hydrochar (HHP), which had higher acetone and cyclohexane adsorption capacities. After five continuous adsorption desorption cycles, the adsorptive capacities of acetone and cyclohexane on HHP decreased by 6.2\% and 7.8\%, respectively. The slight decline in adsorption capacity confirmed the reusability of activated hydrochar as a VOC sorbent. (C) 2018 Elsevier Ltd. All rights reserved.
There are several problems faced by small island developing states (SIDS), especially when it comes to waste management and energy production. There is little land space available for dumping and fuel has to be imported in order to meet energy demands. These problems can be mitigated by using grass cuttings from landscaping, which are often dumped, to produced biogas, which can be used as a fuel. In this study the rates of methane production of 10 different tropical and subtropical species of grasses were determined. Based on the results for 20 g/kg samples, the specific rates of gas production ranged from 2.40 +/- 0.21 NmL/gFM/day (Zoysia matrella) to 6.52 +/- 0.36 NmL/gFM/day (lemon grass). It was also observed that organic dry matter (oDM) loads did not correlate with methane production, suggesting that the oDM content is not necessarily an accurate indicator of a substrate's methane potential, and highlighting areas for further study. The results in this paper provide a database on the rates of methane production of grasses which are common to the tropical and subtropical regions and can be found in several SIDS. (c) 2018 Society of Chemical Industry and John Wiley \& Sons, Ltd.
Converting hemicellulose into valuable platform chemicals is a key step in developing an integrated biorefinery. Traditionally, hemicellulose conversion into xylitol is done in two steps, using mineral acids and enzymes. Here we report a one pot hydrolysis-hydrogenation of hemicellulose to xylitol. We used a combination of either heteropoly acid or biomass-derived organic acid and Ru on carbon as catalyst. Silicotungstic acid, phosphotungstic acid, and lactic acid can be used efficiently in the hydrolysis part. Phosphomolybdic acid was not very active (<5\% yield). The reduction can be done using either hydrogen gas or isopropanol as the reductant. The entire process runs in water, at relatively mild temperatures and pressures (140 degrees C and 20 bar). Lactic acid or phosphotungstic acid combined with Ru/C gave around 70\% xylitol yield in 3 h using H-2 as a reductant. With isopropanol as a reductant, phosphotungstic acid and Ru/C gave a high xylitol yield (82\%), while only similar to 20\% xylitol yield was obtained with lactic acid.
In this work, cellulose modified with maleic anhydride and thiourea (CMT) was synthesized as a novel type of adsorbent to remove heavy-metal ion. The synthesized adsorbent was characterized by Fourier transform infrared spectroscopy, elemental analysis, scanning electron microscopy, thermogravimetric analysis and X-ray diffraction. Batch experiments were performed to investigate the influence of different factors on the adsorption of Cd(II) from aqueous solution. Based on the adsorption data, the adsorption isotherm model was confirmed and the maximum adsorption capacity of Cd(II) from the Langmuir model was found to be 94.47 mg g(-1). The adsorption kinetics indicated that the adsorption process followed pseudo-second-order model. Adsorption/desorption experiments for more than six cycles showed the possibility of repeated use of CMT for the adsorption of Cd(II) from aqueous solutions.
In this study, the effectiveness of NaOH extraction (AE), Fenton oxidation (FO), and synergistic pretreatment using AE and FO for enzymatic saccharification of corn stalks (CS) was compared-by statistical analyses. The results showed that AE-FO treatment resulted in statistically higher enzymolysis efficiency and glucose yield than single AE and single FO treatments. Compared with single AE and FO treatments, AE-FO resulted in statistically significant higher lignin removal and xylan removal, consequently improving the cellulose accessibility to cellulase. Among various synergistic pretreatment parameters, utilizing Plackett Burman design determined the most effective factor improving cellulose accessibility to cellulase was NaOH loading. The results that we obtained could be extended to help further improve the synergistic pretreatment process by using CS for the production of biofuels and sugar-based chemicals.
Dilute acid hydrolysis was employed to generate lipid-dense post-hydrolyzed rice bran (PHRB) which was utilized as feedstock in biodiesel production. Upon drying of the wet PHRB with the entrained dilute acid solution, subsequent carbonization and sulfonation occurred with the material, incorporating significant amounts of sulfur in PHRB as sulfonic acid. The collected dry PHRB was utilized as feedstock in the in-situ (trans)esterification (ISTE) of its lipids to fatty acid methyl esters (FAME), whereby the available acid sites reduced the acid catalyst to be loaded in the reaction system. The optimum reaction conditions under ambient pressures were determined via the Taguchi method and the highest yield achieved was 22.38 +/- 0.28 g FAME/100 g PHRB (82.31\% conversion or reaction yield), and was achieved at 65 degrees C, SSR of 20 mL methanol/g dried PHRB, 12 h reaction time, and 5 wt\% H2SO4 of the PHRB processed. The post-ISTE PHRB was found to still possess the catalytic activity and could be used for the esterification of oleic acid and methanol and appreciable stability. Finally, the FAME-rich product also exhibits free-radical scavenging activity, owing to the presence of bioactive components, which may provide better oxidative stability or could be further recovered as high-value by-products.
The possible use of mustard seeds functionalized with tri-octylamine (TOA) as a novel adsorbent (TOA-M)-BR was used successfully to remove Cr(VI) from sulfate media. The effectiveness of various factors such as, effect of H2SO4 concentration, liquid-to-solid (V/m) ratios, contact time, initial concentrations of Cr(VI), in addition to temperature were investigated. At the optimum conditions (V/m 1.0 Lg-1, H2SO4: 2.5 M, T: 25 \& sect;1 degrees C), (\%R) was >99\% and the maximum uptake reached to 22.67 mg g-1. Cr(VI) uptake process followed the pseudofirst-order rate and thermodynamic parameters were estimated. The obtained data have illustrated that the adsorption process was feasible, spontaneous, and endothermic in nature. The adsorption equilibrium compliance with Langmuir isotherm. The results exhibited that, Cr(III) is not adsorbed under the operating conditions that lead to separate Cr(VI) and Mo(VI) from some fission products such as Eu (III), La(III), Ce(IV), and Y (III) with impregnated (TOA-M)-BR with considerable values of separation efficiency. Both Mo(VI) and Cr(VI) were adsorbed with an efficiency of 90 and 70\%, respectively. (c) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Delignification of biomass is a primary step in biomass pretreatment in fermentation based synthesis of alcoholic biofuels. This paper attempts to give mechanistic insight into ultrasound-assisted delignification of biomass. Parthenium hysterophorus (carrot grass) has been used as the model biomass. The approach of study is to couple simulations of cavitation bubble dynamics to the experiments on delignification. Best values of delignification parameters with ultrasound have been identified as temperature = 303 K, NaOH concentration = 1.5\% w/v, and biomass concentration = 2\% w/v. Characterization of delignified biomass has been carried out using FTIR spectroscopy and XRD and FESEM techniques. Both physical and chemical effects of transient cavitation contribute to delignification. The physical effect of shock waves leads to depolymerization of lignin matrix through homolytic cleavage of phenyl ether alpha-O-4 and beta-O-4 bonds. The chemical effect of radical generation causes hydroxylation/oxidation of the aromatic moieties and side chain elimination. Due to these peculiar mechanisms, ultrasound treatment gives effective delignification at ambient temperature and with lesser requirement of delignifying agents. Cavitation also causes decrystallization of cellulose due to partial depolymerization. Kinetic analysis of delignification at best values of parameters has revealed 2-fold enhancement with ultrasound as compared to mechanically agitated treatment.
Bio-based treatment technologies are gaining great interest worldwide, and significant efforts are being afforded to develop technology for the use of lignocellulosic biomass. The potential of corn stover (CS) as a feedstock for bioethanol production was investigated by creating an optimal pretreatment condition to maximize glucose production. The current study undertook the impact of novel physico-chemical pretreatment methods of CS, i.e., autoclave-assisted oxalate (CSOA) and ultrasound-assisted oxalate (CSOU), on the chemical composition of CS and subsequent saccharification and fermentation for bioethanol production. The delignification was monitored by physicochemical characterizations such as SEM, XRD, FTIR, CHNs, and TGA. The results evidenced that delignification and enzymatic saccharification of the CS pretreated by CSOA was higher than CSOU. The optimum enzymatic saccharification operating conditions were 1:30 g solid substrate/mL sodium acetate buffer at 50 \& DEG;C, shaking speed 100 rpm, and 0.4 g enzyme dosage. This condition was applied to produce glucose from CS, followed by bioethanol production by S. cerevisiae using an anaerobic fermentation process after 72 h. S. cerevisiae showed high conversion efficiency by producing a 360 mg/dL bioethanol yield, which is considered 94.11\% of the theoretical ethanol yield. Furthermore, this research provides a potential path for waste material beneficiation, such as through utilizing CS.
The use of high-pressure CO2/H2O in valorisation of pistachio shell to produce hemicellulose-derived, oligomeric and monomeric sugars and their further transformation to furfural as well as enzymatic transformation of cellulose-rich solids is presented in this work. Different pre-treatment conditions i.e. temperature ranged from 160 to 200 degrees C; reaction time varied between 0 and 30 min and liquid to solid mass ratio between 4 and 8 with constant initial pressure of CO2 of 50 bars were examined. At the optimal pre-treatment conditions, the concentrations of xylose and xylo-oligosaccharide were of 1.7 and 35.5 g/L. Furthermore, this work demonstrates the high-pressure CO2 catalysed production of furfural in an aqueous/tetrahydrofuran system. For model solution containing a mixture of xylose and acetic acid, the optimised furfural yield was as high as 53.3 mol\%, while for real sample of hemicellulose hydrolysate, the furfural yield of 39.6 mol\% and the selectivity of 40.0 mol\% were obtained. Additionally, quantitative glucan to glucose conversion by enzymatic hydrolysis of pre-treated cellulose-rich biomasses was achieved. The promising results achieved confirm that the valorisation of food residues such as pistachio shell using greener alternative methods involving high-pressure CO2 is an efficient technology, which can be integrated into the biorefinery concept. (C) 2018 Elsevier Ltd. All rights reserved.
The fungus Aspergillus saccharolyticus was found to produce a culture broth rich in beta-glucosidase activity, an enzyme which plays an essential role for efficient and complete hydrolysis of lignocellulosic biomass. Direct application of fungal fermentation broths produced on-site in a biorefinery may be an integral part of a biorefinery for lowering the cost associated with the use of commercial enzymes for saccharification of biomass. Utilization of low value slip streams from the biorefinery as substrates for such an on-site enzyme production would be ideal to reduce costs. In order to understand which carbon sources that support growth and trigger A. saccharolyticus to produce beta-glucosidases, carbon sources, ranging from monomer sugars to complex lignocellulosic biomasses, including pretreated and hydrolyzed corn stover fractions, were investigated as substrates and inducers of enzyme production. A convenient micro titer plate experimental setup was developed that facilitated a fast screening for beta-glucosidase activity on the different carbon sources. The greatest beta-glucosidase activity was found when A. saccharolyticus was cultivated on media containing xylose, xylan, wheat bran, and pretreated corn stover. In a refinery, beta-glucosidase production by A. saccharolyticus could with success be based on the biomass hemicelluloses and their degradation products which cannot be converted by conventional yeast. Published by Elsevier Ltd.
Holm oak (Quercus ilex) sapwood was submitted to a hydrothermal treatment and liquid fractions rich in hemicelluloses were obtained. The chemical composition as well as the molar mass were analysed during the experiments. The effect of temperature (130-170 degrees C) and reaction time (5-220 min) on the conversion and molar mass of the obtained hemicelluloses was investigated. The results were compared to previously published data obtained using Norway spruce. The results show that the extraction rate depends strongly on the wood species used. The maximum yield (approximately 60\%) was obtained at 170 degrees C after 20 min. The molar mass of the hemicelluloses decreased during the extraction due to hydrolysis and the pH of the solution decreased as deacetylation occurred simultaneously. Temperature influenced significantly the hydrolysis rate of the macromolecules. Compared to Norway spruce (softwood), the average molar mass in Holm oak (hardwood) was lower under the same reaction conditions. (C) 2017 Elsevier B.V. All rights reserved.
Fibrous adsorbents were prepared by carboxymethylation of waste textile fibers and were used for Cd(II) sorption in comparison with Dowex Mac-3 (DM-3). The prepared sorbents were designated carboxymethyl cellulose-Lyocell strands (CMC-LS) and carboxymethyl cellulose-Lyocell fabrics (CMC-LF). Kinetic and isotherm studies indicated that CMC-LS had the fastest sorption rate with high affinity constants and good column application potential. For the same packed column volume, CMC-LS reached similar to 70\% of its capacity whilst DM-3 reached similar to 57\%. 100\% desorption was achieved using 0.1 M EDTA or HCl. This study therefore suggests a way to recycle waste fibers into adsorbents for treating heavy metal-polluted waters. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
Filamentous fungi from the genus Trichoderma have been widely investigated due to their considerable production of important biotechnological enzymes. Previous studies have demonstrated that the T. harzianum strain IOC-3844 has a high degree of cellulolytic activity. After excluding the native signal peptide, the open reading frame of the T. harzianum endoglucanase III enzyme was cloned in the expression vector pPICZ alpha A, enabling protein secretion to the culture medium. The recombinant plasmid was used to transform Pichia pastoris. Recombinant expression in the selected clone yielded 300 mg pure enzyme per liter of induced medium. The recombinant enzyme proved to be active in a qualitative analysis using Congo red. A quantitative assay, using dinitrosalicylic acid, revealed a high degree of activity at pH 5.5 and around 48 degrees C. This information contributes to our understanding of the cellulolytic repertory of T. harzianum and the determination of a set of enzymes that can be incorporated into mixes for second-generation ethanol production.
Anaerobic digestion technology is regarded as the most ideal technology for the treatment of a distiller in terms of environmental protection, resource utilization, and cost. However, there are some limitations to this process, the most prominent of which is microbial activity. The purpose of this paper is to provide a critical review of the microorganisms involved in the anaerobic digestion process of a distiller, with emphasis on the archaea community. The effects of operating parameters on microbial activity and process, such as pH, temperature, TAN, etc., are discussed. By understanding the activity of microorganisms, the anaerobic treatment technology of a distiller can be more mature. Aiming at the problem that anaerobic treatment of a distiller alone is not effective, the synergistic effect of different substrates is briefly discussed. In addition, the recent literature on the use of microorganisms to purify a distiller was collected in order to better purify the distiller and reduce harm. In the future, more studies are needed to elucidate the interactions between microorganisms and establish the mechanisms of microbial interactions in different environments.
The production of biofuels and biochemicals requires a pretreatment to cleave the composite-like structure of lignocellulosic biomass and thus facilitate further conversion. In the case of liquid-based pretreatment, it is important to know which pretreatment liquids allow for an effective conversion of biomass. For the development of effective pretreatment strategies, simple criteria for a fast evaluation of pretreatment results are advantageous. In this study, we use the example of acetosolv pretreatment of beech wood to explore the influence of composition of the employed acetosolv liquids. To this end, we investigate pretreatment phenomena on different scales including macroscopic disintegration, overall mass balances and compositional changes of beech wood. We relate the investigated phenomena with the type and amount of catalyst acid as well as water content of the employed acetosolv liquids. The results show that disintegration increases with both a higher concentration and acidity of the catalyst acid, while excessive disintegration can be balanced by an increased water content up to equimolar ratios of water and acetic acid. Furthermore, an increasing disintegration correlates with an increasing non-recovered fraction up to a maximum of 40 wt\%. The non-recovered fraction in turn linearly depends on the amount of removed hemicellulose and lignin. Overall, a low lignin content together with complete disintegration after pretreatment in acetosolv liquids with a high water content allows for increased sugar yields in subsequent enzymatic hydrolysis. Thus, disintegration and non-recovered fraction serve as a simple indicator for a first assessment of pretreatment effectiveness.
The production of second-generation (2G) ethanol remains an interesting proposition for the implementation of sustainable and net carbon-neutral energy systems. To be economically viable, 2G biorefineries must make use of all processing streams, including the less desirable pentose (C5) sugar stream. In this work, a strategy of sequential dilute acid and alkaline pretreatment of the lignocellulosic feedstock, switchgrass, was implemented for improving the fermentable sugar yield. The hemicellulose-enriched hydrolysate obtained after dilute acid pretreatment was fermented by a newly isolated wild Scheffersomyces parashehatae strain-UFMG-HM-60.1b; the corresponding ethanol yield (Y-PS) and volumetric productivity (Q(P)) were 0.19 g/g and 0.16 g/L h, respectively. The remaining switchgrass cellulignin fraction was subjected to optimized alkaline delignification at 152 oC for 30 min. Then, the delignified solid fraction was subjected to contiguous enzymatic saccharification and fermentation releasing a glucose (C6) sugar stream. The control yeast strain, Saccharomyces cerevisiae 174, displayed an ethanol Y-PS of 0.46 g/g and Q(P) of 0.70 g/L h for the C6 sugar stream, whereas the above-mentioned wild strain presented Y-PS and Q(P) of 0.29 g/g and 0.38 g/L h, respectively. Upon combining the conversion of hemicellulose (37\%) and cellulose-derived sugars (57\%), the wild S. parashehatae strain provided higher yield (94\%) than the generic S. cerevisiae (90\%). Henceforth, our sequential two-stage pretreatment and fermentation of C5 and C6 sugar streams provides a pathway for maximum utilization of switchgrass carbohydrates for 2G ethanol production.
The liquid product from biomass direct pyrolysis is usually complex and difficult to effectively utilize. By combining hydrothermal conversion and low-temperature pyrolysis, the hemicellulose and cellulose of biomass can be transformed into value-added furfural and levoglucosan (LG), respectively. The effects of temperature during hydrothermal treatment (160-240 degrees C) and subsequent pyrolysis (340-400 degrees C) on the production of furfural and LG were investigated by using three typical agricultural wastes, namely corn stalk, peanut shells, and rice stalk. The maximum furfural yield of 4.2\% was achieved upon hydrolysis of peanut shells at 200 degrees C. The hydrochar produced from peanut shells presented the highest LG yield of 7.3\% (based on original biomass weight) for a pyrolysis temperature of 360 degrees C. Under this optimal condition, the total revenue from various products of the hybrid thermochemical process was estimated at \$0.362 per kilogram of peanut shells, whereas furfural and LG account for 90\% of the revenue. (C) 2020 Elsevier Ltd. All rights reserved.
This study was the first to evaluate the treatment of cotton pulp wastewater by isolated cellulolytic halotolerant bacteria. A cellulolytic halotolerant bacterium was screened from the marine mud domesticated by cotton pulp wastewater using Congo red staining. The strain was obtained as a Bacillus paralicheniformis by physiological and biochemical identification and 16S rRNA sequence analysis. The strain has an optimum growth salinity of 2\% and can be grown using carboxymethylcellulose (CMC) or corncob as a carbon source. Maximum cellulase activities of FPase 0.143 U/mL, CMCase 0.189 U/mL, beta-glucosidase 0.158 U/mL, respectively were achieved in a pH of 6-7 and a temperature of 35 degrees C with 60 h. The chemical oxygen demand removal rate of the bacterium on the diluted cotton pulp wastewater for 6 consecutive days was 71.8\%. These results contribute to the development of sustainable bioprocesses approaching a biorefinery concept. These results help to develop sustainable biological processes in the chemical fiber industry.
Pb (II) is extensively used by various industries and the wastewater generated is hazardous to the environment. In the present study, efficiency of a cheap adsorbent in the form of activated carbon, developed from waste biomass for the Pb (II) adsorption is investigated. With BET surface area 1133.25 m(2)/g and the pore volume 1.41 cm(3)/g, its adsorption capacity for Pb (II) was found to be 823.1 mg/g, at an initial pH of 6.0. The adsorption was best described by the Langmuir isotherm, suggesting monolayer adsorption and was favorable. The adsorption followed second order kinetics, indicating chemisorption of Pb (II), mainly by ion exchange. The adsorption was controlled by the intraparticle diffusion with significant contribution of the film diffusion. With 0.5 g/L of adsorbent dosage, complete removal of Pb (II) ions was achieved from battery industry wastewater, making it safe discharge in water bodies. (c) 2017 American Institute of Chemical Engineers Environ Prog, 36: 1628-1633, 2017
Solid state enzymatic hydrolysis (SSEH) has many advantages, such as higher sugar concentration, lower operating costs, and less energy input. It should be a potential approach for the industrial application of lignocellulosic ethanol. The purpose of this work is to review the enzymatic hydrolysis of lignocellulosic biomass from low to high solids loading and introduce its both challenges and perspectives. The limitations of SSEH, including inhibition effects, water constraint, and rheology characteristic, are summarized firstly. Various strategies for overcoming these limitations are proposed correspondingly. Fed batch process and its feeding strategy to improve the SSEH efficiency are then discussed. Finally, several intensification-methods, hydrolysis reactor, and pilot-and demonstration-scale operations of SSEH are described. In-depth analysis of main limitations and development of novel intensification methods and reactors should provide an effective way to achieve large-scale implementation of SSEH.
The kinetic study of abies wood delignification by H2O2 in the medium acetic acid-water was first carried out in the presence of TiO2 catalyst under mild conditions: temperatures 70-100 degrees C, atmospheric pressure. The oxidative delignification process is described satisfactory by the first order equation in all temperature range. The rate constants varied between 0.80 and 12.3 9 10(-3) min(-1) and the activation energy was near 81 +/- 0.21 kJ mol(-1). The optimal parameters of the delignification process, providing the effective fractionation of abies wood on microcrystalline cellulose and soluble lignin, were established by experimental and numerical methods.
Different strategies were assessed for the production of ethanol from Agave lechuguilla that was pretreated by autohydrolysis. Separate hydrolysis and fermentation (SHF) was compared against simultaneous processes including simultaneous saccharification and fermentation (SSF) and prehydrolysis and simultaneous saccharification and fermentation (PSSF) using different solids (15\%, 20\%, and 25\% w/w) and enzyme loadings (15 FPU/g, 20 FPU/g, and 25 FPU/g glucan). The results showed that the maximum ethanol concentration (53.7 g/L) and productivity (1.49 g/L h(-1)) was obtained at 36 h in the SHF configuration at the highest solids and enzyme loadings (25\% w/v and 25 FPU/g glucan, respectively). The ethanol concentration and productivity obtained in the PSSF configuration at the same time were 45 g/L and 1.25 g/L h(-1), respectively. The SSF configuration exhibited the lowest ethanol concentration and productivity (10.4 g/L and 0.29 g/L h(-1), respectively) at 36 h. The enzyme used, Cellic CTec3, allowed for high glucose yields at the lower enzyme dosage assessed. The SHF configuration exhibited the best results. However, the PSSF configuration can be considered an attractive alternative because it eliminated the need for solid-liquid separation devices, which simplifies the industrial implementation of the process.
The seaweed Ulva prolifera, distributed in inter-tidal zones worldwide, contains a large percentage of cellulosic materials. The technical feasibility of using U. prolifera residue (UPR) obtained after extraction of polysaccharides as a renewable energy resource was investigated. An environment-friendly and economical pretreatment process was conducted using hydrogen peroxide. The hydrogen peroxide pretreatment improved the efficiency of enzymatic hydrolysis. The resulting yield of reducing sugar reached a maximum of 0.42 g/g UPR under the optimal pretreatment condition (hydrogen peroxide 0.2\%, 50 degrees C, pH 4.0, 12 h). The rate of conversion of reducing sugar in the concentrated hydrolysates to bioethanol reached 31.4\% by Saccharomyces cerevisiae fermentation, which corresponds to 61.7\% of the theoretical maximum yield. Compared with other reported traditional processes on Ulva biomass, the reducing sugar and bioethanol yield are substantially higher. Thus, hydrogen peroxide pretreatment is an effective enhancement of the process of bioethanol production from the seaweed U. prolifera. (C) 2016 Elsevier Ltd. All rights reserved.
Branches from three transgenic poplar lines and their wild type line 107 were used to study the effect of lignocellulosic composition and structure on the production of glucose and ethanol. Experimental results showed that the transgenic line 18-1 had the high cellulose content and amorphous fibril structure. After poplar meals were pretreated with 10\% NaOH and a mixture of hydrogen peroxide and acetic acid, their lateral order index decreased significantly. The highest glucose yield in enzymatic hydrolysis and ethanol yield from the substrate of 18-1 was much higher than that from feedstock of 107 by 192.7\% and 108.7\%, respectively. Scanning electron microscopy images confirmed that lignocellulose from the 18-1 could be destroyed by chemicals more easily than those from other lines. These results demonstrated that changing lignocellulose structure could be more effective on improving the digestibility and enzymatic hydrolysis of poplar biomass than increasing the cellulose content in biomass. (C) 2013 Elsevier Ltd. All rights reserved.
Lantana camara contains 61.1\% (w/w) holocellulose and can serve as a low-cost feedstock for bioethanol production. Acid hydrolysis (3.0\%, v/v H2SO4, 120 degrees C for 45 min) of L. camara produced 187.14 mg/g total sugars along with fermentation inhibitors such as phenolics (8.2 mg/g), furfurals (5.1 mg/g) and hydroxy methyl furfurals (6.7 mg/g). Sequential application of overliming (pH 10.0) and activated charcoal (1.5\%, w/v) adsorption was used to remove these toxic compounds from the acid hydrolysate. The acid-pre-treated biomass of L. camara was further delignified through combined pretreatment of sodium sulphite (5.0\% w/v) and sodium chlorite (3.0\% w/v), which resulted in about 87.2\% lignin removal. The enzymatic hydrolysis of delignified cellulosic substrate showed 80.0\% saccharification after 28 h incubation at 50 degrees C and pH 5.0. Fermentation of acid and enzymatic hydrolysates with Pichia stipitis and Saccharomyces cerevisiae gave rise to 5.16 and 17.7 g/L of ethanol with corresponding yields of 0.32 and 0.48 g/g after 24 and 16 h, respectively. (C) 2010 Elsevier Ltd. All rights reserved.
An intracellular beta-xylosidase (AbXyl), from the thermoalkaline Anoxybacillus sp. 3M, was purified and characterized. The homodimeric enzyme (140 kDa) was optimally active at 65 degrees C and pH 5.5, exhibited half life of 10 hat 60 degrees C, 78 and 88\% residual activity after 24 h, at pH 4.5 and 8.0, respectively. Fe2+, Cu2+, Al3+, Ag+ and Hg2+ inhibited the enzyme; the activity was moderately stimulated by SDS and not influenced by beta-mercaptoethanol. In the presence of p-nitrophenyl-beta-o-xylopyranoside, AbXyl exhibited Km of 0.19 mM, Kcat of 453.29 s(-1), Kcat Km(-1) of 2322 s(-1) mM and was moderately influenced by xylose (Ki 21.25 mM). The enzyme hydrolyzed xylo-oligomers into xylose and catalyzed transxylosilation reactions also in presence of alcohols as acceptors, producing xylo-oligosaccharides and alkyl-xylosides. Finally AbXyl was applied towards a statistically optimized process of brewery's spent grain bioconversion, highlighting the important role of this biocatalyst in reaching high yields of fermentable sugars. (C) 2018 Elsevier B.V. All rights reserved.
This paper reviews and assesses conditions for increased and efficient use of biomass in Central America (CA), providing an overview of conditions for biomass supply in each country. Then, a Fuzzy Multi-Actor Multi-Criteria Decision-Making (MCDM) method is applied to identify a portfolio of biomass conversion technologies appropriate for CA, considering technical, economic, environmental and socio-political aspects. The work is motivated by the relatively large availability of biomass in CA at the same time as current conversion of biomass is carried out in inefficient processes. The assessment of technologies includes thermochemical processes (pyrolysis, combustion and gasification) for production of different energy carriers, including improved cooking stoves (ICSs). The most promising biomass feedstocks in the region are residue based; animal (manure), forest and agricultural origin. We show that around 250 PJ/year could be available for the energy sector, which is equivalent to 34\% of primary energy supply for CA. It is concluded that in the short term promoting and implementing ICSs will give the largest improvement in the efficiency of biomass use, whereas on the long term small combustion plants seem to be the best choice for transforming CA's biomass into a clean and sustainable energy carriers, boosting economy and industrial development. Results show that the introduction of ICSs will result in an annual saving in the range of 4-8 Mt of fuelwood (59-113 PJ). Moreover, even when the investment cost of the cooking stoves is considered, ICSs yield economic savings to fuelwood consumers compared to traditional stoves. The total savings during the first year of implementation would be in the range of 19-152 US\$/stove. (C) 2016 Elsevier Ltd. All rights reserved.
The synergistic effect of pre-impregnation by sulphuric acid and steam explosion has been investigated. Sugar recovery by water extraction and cellulose digestibility by enzymes have been considered. The acid diffusion inside a representative particle, having thickness of 0.7 mm, has been modelled on the basis of available models and diffusion coefficients. The experiments of acid impregnation have pointed out a plateau of the acid uptake after 10 min corresponding to an acid adsorption of 22 g/kg of dry stover. An experiment of acid desorption from the pre-impregnated biomass particles to a new bulk of pure water (reverse diffusion), has confirmed that only a small fraction of the uptaken acid remained free, while most has been consumed by the substrate. Nine conditions have been tested for the steam explosion treatment selecting the temperature of 180, 190, 200 degrees C and sulphuric acid loadings of 0, 1.5, 3 wt.\%. The maximum sugar recovery by water extraction is produced by a SE treatment of 190 degrees C for 5 min and an acid loading of 1.5 wt.\%; at these conditions 25\% of the sugars in the feedstock can be recovered as monomers or oligomers. The acid has greatly improved the sugar solubility, e.g. at 180 degrees C the sugar recovery has been only 1.5\% without acid, while by using 3 wt.\% of acid the sugar recovery has increased to 16.8\%. Also the cellulose digestibility has been improved by the acid pre-impregnation, after 48 h of digestion the yield of glucose reached 93\% of the theoretical by using the substrate that was preimpregnated with 3 wt.\% of acid an treated at 190 degrees C. The high acid loading has also been required to achieve the best recovery of glucose (85\% of the initial glucan) as sum of water extraction and 48 h hydrolysis. (C) 2007 Elsevier B.V. All rights reserved.
Agro-based final discharge is one of the major contributors to wastewater in the world. It creates high demand for efficient treatment. The electrocoagulation process can be used for agro-based wastewater treatment. The performance of the electrocoagulation process is based on several parameters, including the electrode materials, electrolysis time, current density, and electrolyte support. Agro-based industrial wastewater (AIW) treatment processes depend on the characteristics of the wastewater. The removal of organic content from various sources of AIW can reach up to more than 80\%. Some studies show that the performance of the electrochemical process can be increased using a combination with other methods. Those other methods include biological and physical treatment. The results of previous research show that organic content and color can be degraded completely. The relationship between the energy consumption and operating cost was analyzed in order to show the efficiency of electrocoagulation treatment.
For ammonia-sulfuric acid pretreatment of Achnatherum splendens, the ground biomass was first pretreated by soaking in aqueous ammonia with 10 wt\% of ammonia at 55 degrees C with 12:1 of liquid-to-solid ratio (based on wt) for 36 h. Then the pretreated solids were further treated with 0.5-2\% (w/v) sulfuric acid at liquid-to-solid ratio of 8:1-15:1 (v/w) for 0.5-3 h at 100 degrees C. Increasing sulfuric acid concentration and reaction time in the second stage had significant effect on hemicellulose solubilization. Increases in sulfuric acid concentration and reaction time in the second stage caused significant decrease in hemicellulose and significant increases in cellulose and ligning. However, liquid-to-solid ratio had no significant effects on hemicellulose solubilization in the second stage. Liquid-to-solid-ratio had also no significant effects on the yield of hemicellulose, cellulose and lignin in the solids after sulfuric acid pretreatment in the second stage. The optimum treatment conditions of the ammonia-sulfuric acid pretreatment were: 10 wt \% of ammonia, 55 degrees C, 36 h of reaction time, 12:1 of liquid-to-solid ratio (based on wt) in the first stage; 1.5 \% (w/v) sulfuric acid, 8:1 (v/w) of liquid-to-solid ratio, 2 h of reaction time and 100 degrees C in the second stage. Under these conditions, 91.19\% hemicellulose was solubilized-acid-the-content of cellulose was increased to 75.49 \%.
Recent advances in biomass conversion technologies have shown a promising future toward fermentation during xylitol production. Xylitol is one of the top 12 renewable added-value chemicals that can be obtained from biomass according to US Department of Energy (USDOE). Currently, xylitol accounts for approximately US\$823.6 million of annual sales in the market, and this amount is expected to reach US\$1.37 billion by 2025. This high demand has been achieved owing to the chemical conversion of hemicellulosic hydrolysates from different lignocellulosic biomasses, which is a costly and non-ecofriendly process. Xylose-rich hemicellulosic hydrolysates are the major raw materials for xylitol production through either chemical or biotechnological routes. Economic production of a clean hemicellulosic hydrolysate is one of the major bottlenecks for xylitol production on the commercial scale. Advancements in biotechnology, such as the isolation of novel microorganisms, genetic manipulation of xylose metabolizing strains, and modifications in the fermentation process, can enhance the economic feasibility of xylitol production on the large scale. Furthermore, xylitol production in integrated biorefineries can be even more economic, given the readily available raw materials and the co-use of steam, electricity, and water, among others. Exploring new biotechnology techniques in integrated biorefineries would open new markets and opportunities for sustainable xylitol production to fulfill the market's growing demands for this sugar alcohol. This article is a review of the advancements reported in the whole biotechnological process for xylitol production, and involve pretreatment technologies, hemicellulosic hydrolysate preparation, xylose conversion into xylitol, and product recovery. Special attention is devoted to current metabolic engineering strategies to improve this bioprocess, as well as to the importance of xylitol production processes in biorefineries.
The production of xylooligosaccharides (XOS) from lignocelluloses with a simple process and less chemical loading is challenging. Previously, some metal salts have been proven to depolymerize hemicellulose into xylose at low doses. However, few metal salts have been reported for the production of XOS from lignocelluloses. In this study, FeCl3 hydrolysis and FeCl2 hydrolysis of switchgrass were compared to produce XOS, then FeCl3-hydrolyzed switchgrass was delignified by sodium perborate (SPB) pretreatment for producing monosaccharides. The results showed that the highest XOS (DP 2-6) yield of 40.7\% was obtained from switchgrass by 25 mM FeCl3 hydrolysis at 160 degrees C for 50 min. A high lignin removal (75.5\%) and glucan retention (90.5\%) of FeCl3-hydrolyzed switchgrass was obtained by 8\% SPB pretreatment at 70 degrees C for 4 h. After cellulase (20 FPU/g dry mass) hydrolysis of SPB-pretreated switchgrass, 87.5\% glucose, and 95.0\% xylose were obtained. The results suggest that FeCl3 hydrolysis combined with SPB pretreatment is an efficient and novel method for producing XOS and monosaccharides from switchgrass under relatively mild conditions.
The hydrodynamic environment in bioreactors affects the oxygen transfer rate and the shear conditions during microbial cultivations. Therefore, assessment of the effect of the hydrodynamic environment on cellular morphology can contribute to favoring the production of metabolites of interest. The aim of this work was to use image analysis in order to quantify the fragmentation of Aspergillus niger pellets in a conventional bioreactor operated using different impeller speeds, air flow rates, and impeller configurations including Rushton turbines and Elephant Ear impellers, with evaluation of the influence of the hydrodynamic environment on the production of cellulolytic enzymes. An empirical kinetic model was proposed to describe the dynamics of pellet fragmentation and quantify the shear conditions. The results showed that the agitation speed affected the dynamics of pellet fragmentation in two ways, by accelerating the damage process and by increasing the magnitude of the fragmentation. Both endoglucanase and beta-glucosidase production exhibited a linear relationship with the pellet fragmentation percentage, which was directly related to the shear conditions. Interestingly, beta-glucosidase production was favored under high shear conditions, while the highest endoglucanase production occurred under low shear conditions. These findings may be useful for defining suitable systems and operating conditions for the production of metabolites including enzymes in bioreactors, as well as defining conditions that favour a specific pre-determined enzyme cocktail.
The objective of this study was to evaluate the fermentation conditions that led to the optimization of H-2 production from coffee waste (wastewater, pulp and husk) and the taxonomic and functional characterization of autochthonous microorganisms. Assays in batch reactors with microbial consortium bioaugmentation (bacteria and fungi) evaluated the pH (4.82-8.18), pulp and husk concentration (6.95-17.05 g/L) and headspace factor (33.18-66.82\%) by means of rotational central composite design and response surface. Operating conditions in the reactor optimized for 3.04 LH2/Ld were at pH 7.0, 7 g/L pulp and husk and 30\% headspace. The main metabolites observed were butyric acid (3838 mg/L), isobutyric acid (506 mg/L), methanol (226 mg/L) and butanol (156 mg/L). Clostridium sp. (87.9\%), Lactobacillus sp. (1.7\%), Kazachstania sp. (18.6\%) and Saccharomyces sp. (16.3\%) were the main genera identified in the optimized reactor, which had functional gene diversity for H-2 production, alcoholic fermentation, cellulose degradation, lignin, hemicellulose and phenol. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Ozone pretreatment of coffee husks (CH) was evaluated to generate hydrolysates for biogas production and to preserve cellulose of the solid phase for 2G ethanol production. Pretreatment variables included liquid-to-solid ratio (LSR), pH and specific applied ozone load (SAOL). Considering single-stage anaerobic digestion (AD), the highest methane production (36 NmL CH4/g CH) was achieved with the hydrolysate generated in the experiment using LSR 10 mL/g, pH 11 and SAOL 18.5 mg O-3/g CH, leading to 0.064 kJ/g CH energy recovery. Due to the presence of toxic compounds in the hydrolysate, the addition of powdered activated carbon (4 g/L) to the reactor enhanced biogas production, leading to 86 NmL CH4/g CH yield and 0.58 kJ/g CH energy recovery. When two-stage AD was applied, methane production resulted in 49 NmL CH4/g CH, with additional 19 NmL H-2/g CH production, resulting in a net 0.26 kJ/g CH energy recovery.
The white-rot fungi Ganoderma lucidum, Phanerochaete chrysosporium, Pleurotus ostreatus, Pleurotus pulmonarius and Trametes sp were used for biological pretreatment of Eucalyptus grandis sawdust. Analysis by scanning electron microscopy and Fourier transform infrared spectroscopy showed that P. ostreatus and P. pulmonarius promoted more extensive selective modifications in the lignin content. Enzymatic hydrolysis of E. grandis sawdust cellulose with and without biological pretreatment was analyzed in terms of an equation that accounts for the initial delay that precedes the attainment of the maximal rate of hydrolysis, the presence and exhaustion of an easily hydrolysable fraction and the presence of a second fraction more difficult to be hydrolyzed. The equation could be fitted to all experimental curves including the hydrolysis curve of microcrystalline cellulose for comparison purposes. In general terms, the biological pretreatments diminished the initial delay, increased the easily hydrolysable fraction and generated a second hydrolysable fraction. The generation of an easily hydrolysable cellulose fraction obeyed the following decreasing sequence: P. ostreatus (16.7\% of total cellulose) > P. pulmonarius (15.4\%) > Trametes sp. (10.1\%) >> P. chrysosporium (2.8\%) approximate to no treatment (2.8\%). The generation of the second hydrolysable fraction was more efficient in the case of P. pulmonarius and P. ostreatus pretreatments. For the latter, the total amount of reducing sugars released after 48 h of saccharification of sawdust was increased from 2.5 mu mol/mL to 48.0 mu mol/mL. (C) 2014 Elsevier B.V. All rights reserved.
The world's first industrialized coal-based fuel ethanol (CBFE) and emerging second-generation fuel bioethanol (SGFB) routes are promising alternatives and potential competitors to the conventional first-generation fuel bioethanol (FGFB) route. Understanding the comprehensive competitiveness of the three fuel ethanol production routes is important for the development of clean and low-carbon transportation worldwide. However, there is currently a dearth of related knowledge and scientific data. In this study, we identified and compared the strengths and weaknesses of the three fuel ethanol production routes using an assessment framework that integrates life cycle assessment, techno-economic analysis, and entropy weight method. Environmental performance was investigated with the 18 midpoint impact categories of the ReCiPe 2016 method and modeled using the SimaPro software. Economic performance was represented using the net present value, dynamic payback period, and internal rate of return. The results demonstrated the highest comprehensive score in the SGFB route owing to its excellent environmental performance, which will likely address the unsustainability of the FGFB route through the efficient utilization of agricultural residuals. Owing to its considerable economic benefit, the industrialization of the CBFE route not only offers a new downstream chain in the coal industry but also diversifies the sources of fuel ethanol away from biomass. However, such a promising alternative faces a substantial challenge associated with its significant environmental impact, especially with its high greenhouse gas emissions. These results provide valuable information on the relative advantages and disadvantages of the CBFE, FGFB, and SGFB routes for scientific tradeoffs and decisions.
Concern about pollution caused by the incorrect disposal of plastic materials has led to an increasing interest in packaging made from natural resources and biodegradable materials. In this context, cassava starch-based foams incorporated with Cabernet Sauvignon grape stalks, one of the main residues from the wine industry, were prepared by thermal expansion, a simple and fast process. Grape stalks in small granulometries can provide a homogeneous matrix and help improve foam resistance. Glycerol, a by-product of the biodiesel production process, was added to improve the batter processability and the flexibility of the foams. Therefore, the influence of formulation parameters, such as the percentage of glycerol and grape stalks addition, and the particle size of the stalks was studied using a central composite experimental design. The desirability function of Statistica software was used to obtain a formulation that presented better properties for the foams. Results showed that the formulation with 13.6 wt\% glycerol, 18.4 wt\% grape stalks in the smallest particle size analyzed (o < 0.18 mm) was able to improve mechanical and humidity related properties and density of the foams. These results indicate that the foams developed in this study could be used as a substitute for EPS trays.
A novel porous bioadsorbent for metal ion binding (Pd2+ and Cd2+) was successfully prepared from lignocellulosic biomass in ionic liquid by homogeneous succinoylation and sequent chemical cross-linking. The morphology of the bioadsorbent and the interaction between bioadsorbent and metal ions was revealed by scanning electron microscopy and Fourier transform infrared spectroscopy. Results showed that the adsorption mechanism of the bioadsorbent was an ion exchange. A lower dose of cross-linker or higher carboxyl content increased the adsorption capacities of Pd2+ and Cd2+. The adsorption capacities of Pd2+ and Cd2+ remarkably increased as the pH of metal ion solutions increased. The pores in the bioadsorbent greatly favored the diffusion and adsorption of metal ions, and the adsorption equilibrium time was about 50 min. The adsorption of metal ions could be well explained by the Langmuir model, and the maximum adsorption capacities of Pd2+ and Cd2+ were 381.7 and 278.6 mg/g.
This study investigated the potential use of quince seed to improve the rheological, melting, textural and sensory characteristics of ice cream. The high dietary fiber, polysaccharide and protein contents of these seeds made them a candidate to achieve these aims due to their water-holding properties, gelation behavior, and emulsifying characteristics. Four different formulations were developed that contained quince seed powder (QSP) at levels of 0, 0.25, 0.50 and 0.75\%. In general, inclusion of 0.25\% QSP decreased the flow behavior parameters, but 0.50\% QSP had no effect on the rheological parameters of the mixes compared with the control mix. The viscosity, yield stress and thixotropic behaviors of mixes were enhanced by the addition of 0.75\% QSP due to the occurrence of interactions and stabilizations. This modification also provided weak gel characteristics and a higher material stiffness property to the mixes, which indicated the presence of a large number of intermolecular interactions. Complex modulus/viscosity and loss tangent variations also supported the flow behavior improvement of the QSP added mixes. Better melting properties and textural characteristics were observed for the 0.5 and 0.75\% QSP added samples. Reduction in the melting rate and retardation of complete melting times were achieved by QSP addition. The effect of QSP on reducing the ice crystallization caused to decrease the hardness of the ice cream and resulted in a smooth product with a higher overall acceptability. The enrichment of ice cream with QSP could be an effective way to enhance the nutritional and structural characteristics of dairy products. (c) 2018 Elsevier Ltd. All rights reserved.
Switchgrass (Alamo) was pretreated with phosphoric acid (0.75 and 1\%, w/w) at three temperatures (160, 175 and 190 degrees C) and time (5, 7.5 and 10 min) using a steam gun. The slurry after pretreatment was liquefied by enzymes and the released sugars were fermented in a simultaneous saccharification and co-fermentation process to ethanol using ethanologenic Escherichia coli strain SL100. Among the three variables in pretreatment, temperature and time were critical in supporting ethanol titer and yield. Enzyme hydrolysis significantly increased the concentration of furans in slurries, apparently due to release of furans bound to the solids. The highest ethanol titer of 21.2 +/- 0.3 g/L ethanol obtained at the pretreatment condition of 190-1-7.5 (temperature-acid concentration-time) and 10\% solids loading accounted for 190 +/- 2.9 g ethanol/kg of raw switch grass. This converts to 61.7 gallons of ethanol per ton of dry switchgrass, a value that is comparable to other published pretreatment conditions.
Two materials were produced from sewage sludge by: (1) pyrolysis of dried sewage sludge (PS); (2) chemical activation of dried sewage sludge with ZnCl2 followed by pyrolysis (AS). The aim was to study the application of these materials for metal purification from water and to determine the efficiency of each material. Although AS displayed higher capacity, both PS and AS were able to adsorb these metals and the preferential order was equal: Hg(II) > Pb(II) > Cu(II) > Cr(III). For each metal-adsorbent pair, metal adsorption was highly pH dependent. In all cases the equilibrium was well described both by the Langmuir and the Freundlich isotherms. At the corresponding optimum pH, AS showed the following adsorption capacities: 175.4, 64.1, 30.7 and 15.4 mg/g of Hg(II), Pb(II), Cu(II) and Cr(III), respectively. These results indicate the potential application of these sewage sludge based adsorbents for the treatment of metal polluted effluents. (C) 2007 Elsevier Ltd. All rights reserved.
Lignocellulosic biomass (LB) is a promising source that has the potential to revolutionize the world of bioenergy, bioproducts, and nondigestible dietary components. As a substrate, LB has proven to be particularly attractive for the production of high-value cello-oligosaccharides (COS) and xylo-oligosaccharides (XOS), which offer diverse applications in the food, biopharmaceutical, and other industries, as well as potential health benefits, including prebiotic and antidiabetic effects. However, despite these promising developments, the manufacturing of these oligosaccharides remains a challenge due to slow reactions and low yields. Therefore, this review presents various pretreatment techniques to improve enzymatic hydrolysis, as well as the possibilities of employing a multi-step process and utilizing thermostable enzymes to enhance the production of COS and XOS from LB. Additionally, this review addressed the potential for by-product recovery during the XOS and COS production and the separation of beta-glucosidase enzymes using the ``separation-adsorption{''
Enzymatic/mild acidolysis lignin was extracted from both unbleached and bleached eucalyptus pulp, and the difference in lignin structures was analyzed by nuclear magnetic resonance spectroscopy. The unbleached pulp lignin was chlorinated with chlorine dioxide, and the mechanism of adsorbable organic halide (AOX) formation was investigated. Chlorinated reaction products were detected by gas chromatography-mass spectrometry. There is a possibility of producing three different chlorobenzene or chlorophenol products from S/S lignin dimers that are connected with beta-O-4 bonds. Based on quantum chemistry theory, three reaction pathways were investigated using molecular simulation techniques. The results showed that pathway 1 possessed the lowest reaction activation energy, which made it the most favored thermodynamically. The beta-O-4 bond of the lignin dimer was cleaved. Following that scission, 2-chloro-3,5-dimethoxy-methyl benzene was the most likely product to be generated from the chlorination reaction of the syringyl unit. These results provide theoretical guidance for further reduction of AOX in chlorine dioxide bleaching.
In realizing the vast potential of lignocellulosic biomass residues generated by oil palm industry under the regime of `one-size-fits-all' biorefinery concept, supercritical carbon dioxide (SC-CO2) technology offers great promise. Herein, we demonstrated a new eco-friendly pretreatment of oil palm trunk biomass based on SC-CO2 under controlled conditions of pressure (25, 35 and 45 MPa), temperature (80, 100 and 120 degrees C) and moisture content (0, 20, 40 and 60 \%), and investigated their effect on enzymatic hydrolysis yields of the pretreated fractions. During pretreatment, biomass sample reacted with hot water in SC-CO2 which led to high diffusivities, promoting its disruption and xylan solubilisation as supported by various characterization techniques. This study illustrates that hydrolysis yields are influenced by process parameters, particularly the moisture content played a crucial role in the biomass disruption. The SC-CO2 pretreatment resulted in enhanced digestibility for all the pretreated fractions compared to the untreated biomass.
The natural world abounds in lignocellulosic biomass, which is an environmentally friendly renewable resource. Cellulose nanofibrils (CNFs) made from biomass have the advantages of high optical transparency, light weight, good mechanical properties, high specific surface area and biodegradability. Increasing applications of CNFs have been identified in emerging high-tech fields, such as flexible electronics and clean energy. A variety of thermal management materials have been discussed in flexible electronic products. This paper reviews the merits of CNFs compared to other polymers in flexible electronic products and emphasizes the application status of CNF-based thermal management materials in flexible electronic products. The thermal conductivities of the CNF-based composites are analyzed with respect to the heat transfer mechanism, the thermal conductivity of the polymer, the loading of the filler, the size and morphology of the filler, the type of filler, and the surface treatment of the filler. Current challenges and future research opportunities are also discussed, offering a reasonable and scientific route for the structural design of future flexible thermal management materials that will promote the development of the flexible electronics industry.
Now-a-days, construction of energy efficient buildings is highly in demand all over the world. The main focus of this study is to utilize waste marble sludge (WMS) in the production of energy efficient burnt clay bricks on industrial scale. For this purpose, WMS was obtained from a local marble industry. Burnt clay bricks were prepared, in an industrial brick kiln under actual field conditions, using various dosages of WMS (i.e., 5\%, 10\%, 15\%, 20\% and 25\% by weight of clay) and were examined for different physico-mechanical and thermal properties. It was observed that lightweight bricks can be manufactured using WMS, which are helpful in reducing the overall construction costs. Although the reduction in compressive strength was observed with WMS incorporation in clay bricks, 15\% replacement level exhibited satisfactory strength requirements. Clay bricks showed increase in apparent porosity and water absorption with increasing WMS content. A porous structure having interconnected and irregular shaped open pores was observed after incorporating WMS in clay bricks, which improved the thermal insulating properties. Brick specimens incorporating up to 15 wt WMS showed decrease in thermal conductivity by about 16\%. Based on this study, 15 wt\% WMS is deemed optimum for the manufacturing of burnt clay bricks leading towards sustainable, economical, environment friendly and energy efficient construction. (C) 2017 Elsevier Ltd. All rights reserved.
Nanocellulose has gained increasing attention during the past decade, which is related to its unique properties and wide application. In this paper, nanocellulose samples were produced via hydrolysis with ionic liquids (1-ethyl-3-methylimidazole acetate (EmimOAc) and 1-allyl-3-methylimidazolium chloride (AmimCl)) from microcrystalline celluloses (Avicel and Whatman) subjected to enzymatic pretreatment. The obtained material was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). The results showed that the nanocellulose had a regular and spherical structure with diameters of 30-40 nm and exhibited lower crystallinity and thermal stability than the material obtained after hydrolysis with Trichoderma reesei enzymes. However, the enzyme-pretreated Avicel had a particle size of about 200 nm and a cellulose II structure. A two-step process involving enzyme pretreatment and hydrolysis with ionic liquids resulted in the production of nanocellulose. Moreover, the particle size of nanocellulose and its structure depend on the ionic liquid used.
Almond shell, a by-product obtained from the nut industry, was valorised into low degree of polymerisation xylooligosaccharides using alkaline pretreatment and enzymatic hydrolysis. The effect of particle size on hemicellulose recovery upon pretreatment was studied using 1 and 2 M NaOH. It was observed that particle size significantly influences hemicellulose recovery, as particles below 120 mu m resulted in near complete recovery at 2 M NaOH. Enzymatic hydrolysis of hemicellulose was optimised using response surface methodology, to obtain efficient xylooligosaccharides production at low enzyme dose and high substrate concentration. For higher XOS yield, an enzyme dose of 10 U and substrate concentration < 2\% was optimal. The in-vitro human faecal fermentation study revealed no significant difference in gas and short chain fatty acid level among substrates evaluated. It was observed that short chain oligosaccharides produce higher level of acetate than medium chain oligosaccharides.
The objective of this work was to evaluate the effect of replacing crude protein of soybean meal by slow-release urea on the performance, carcass traits, and feeding costs of feedlot Nelore steers. Forty-eight Nelore steers were used, with an average age of 22 months and weight of 367.95 +/- 18.52 kg. A completely randomized design was used with four treatments: SM, 8.91\% soybean meal and 0\% slow-release urea (SRU); OP33, 6.01\% soybean meal and 0.46\% SRU; OP67, 2.94\% soybean meal and 0.94\% SRU; and OP100, 0\% soybean meal and 1.41\% SRU. No difference was observed between treatments for the variables initial weight, final weight, average daily gain, carcass gain, dry matter intake, feed conversion, biological efficiency, hot carcass weight, carcass yield, and feed cost of produced arroba. Slow-release urea, used to partially or totally replace protein of soybean meal in the diet, does not modify the performance, carcass traits, and economic efficiency of feedlot cattle.
This work deals with the capture of phosphorus from aqueous solutions by biosorption onto zirconium loaded okara (ZLO). The batch-mode experiments were conducted to examine the effect of pH, biosorbent dose, initial phosphorus concentration, contact time, and temperature on the process. It was found that, the adsorption was most favored in the pH range of 2-6. The optimal doses for the adsorption, at initial phosphorus concentrations of 5, 10, 25, 50 mg/L were 2, 3, 7, 10 g/L, respectively. The maximum adsorption capacity of ZLO was approximately 44.13 mg PO4/g at 298 K. The phosphate removal was rapid, reaching 95\% in 30 min. Freundlich model best fitted the equilibrium data, while Pseudo-second order model satisfactorily described the kinetic results. Thermodynamic analysis revealed feasible, spontaneous, and endothermic nature of the process. The research would be beneficial for developing a promising, eco-friendly phosphorus biosorbent from a plentiful AWB - okara. (C) 2014 Elsevier Ltd. All rights reserved.
Microcrystalline cellulose (MCC) was performed as a mode substrate to investigate its potential ability of bioconversion in a novel combined pretreatment of ball milling (BM) and/or microwave irradiation (MWI). The variation of structure characteristics of MCC before/after pretreatment were investigated, including crystallinity index (CrI), size of crystal (S-C), specific surface area (SSA) and degree of polymerization (DP). Their correlation with the rate of enzymatic hydrolysis was differentiated by an optimized equation which indicated the rate of hydrolysis was much more sensitive to CrI than SSA and DP. To achieve the same or higher glucose yield of BM for 3 h and 6 h, BM for 1 h with MWI for 20 min could save 54.8\% and 77.40\% energy consumption, respectively. Moreover, chemicals were not required in this process. It is concluded that the combination of BM and short time MWI is an environment-friendly, economical and effective approach to treat biomass. (C) 2012 Elsevier Ltd. All rights reserved.
An efficient processing of organic solid residues will be pivotal in the development of the circular bioeconomy. Due to their composition, such residues comprise a great biochemical conversion potential through fermentations. Generally, the carbohydrates and proteins present in the organic wastes cannot be directly metabolized by microorganisms. Thus, before fermentation, enzymes are used in a hydrolysis step to release digestible sugars and nitrogen. Although enzymes can be efficiently produced from organic solid residues in solid-state fermentations (SsF), challenges in the development and scale-up of SsF technologies, especially bioreactors, have hindered a wider application of such systems. Therefore, most of the commercial enzymes are produced in submerged-liquid fermentations (SmF) from expensive simple sugars. Instead of independently evaluating SsF and SmF, the review covers the option of combining them in a sequential process in which, enzymes are firstly produced in SsF and then used for hydrolysis, yielding a suitable medium for SmF. The article reviews experimental work that has demonstrated the feasibility of the process and underlines the benefits that such combination has. Finally, a discussion is included which highlights that, unlike typically perceived, SsF should not be considered a counterpart of SmF but, in contrast, the main advantages of each type of fermentation are accentuated in a synergistic sequential SsF-SmF.
Currently, the modern concept biorefinery industries require a consolidated, robust and cost-effective bioprocess applied to multi-products manufacturing. In alignment, this work presents biomass pretreatment of Pennisetum purpureum grass and integrated developments for carbohydrates portions utilization as carbon source for xylitol and ethanol production in intensified process conducted in column reactor with fluidized bed configuration, homogenized simply by air insertion. Primarily, by using hemicellulosic portion from acid hydrolysis, xylitol production was evaluated in column fluidized bed reactor by using the novel-wild Brazilian yeast Candida Tropicalis UFMGBX12-a verifying YP/S and Qp of 0.26 g/g and 0.06 g/L.h, respectively. Forwardly, the remaining celulignin from the acid hydrolysis was subjected to alkaline pretreatment, followed by Semi-Simultaneous saccharification and Fermentation process, in an intensification approach performed in column fluidized bed reactor, applied to ethanol production by Scheffersomyces Shehatae UFMG-HM 52.2. Enzymatic hydrolysis of pretreated biomass comprised 90\% of glucose yield in 72h of saccharification, while ethanol productivity of 0.21 g/L.h, was found in 24 h of fermentation process. These new developments conferred potential use of Pennisetum purpureum grass as carbon source for xylitol and ethanol production in column reactor towards sustainable intensification process implementation.
The strength of the interphase between the reinforcements and the matrix has a major role in the mechanical properties of natural fiber reinforced polyolefin composites. The creation of strong interphases is hindered by the hydrophobic and hydrophilic natures of the matrix and the reinforcements, respectively. Adding coupling agents has been a common strategy to solve this problem. Nonetheless, a correct dosage of such coupling agents is important to, on the one hand guarantee strong interphases and high tensile strengths, and on the other hand ensure a full exploitation of the strengthening capabilities of the reinforcements. The paper proposes using topographic profile techniques to represent the effect of reinforcement and coupling agent contents of the strength of the interphase and the exploitation of the reinforcements. This representation allowed identifying the areas that are more or less sensitive to coupling agent content. The research also helped by finding that an excess of coupling agent had less impact than a lack of this component.
The current study presents the first ever report of surfactant (Tween-20) assisted ionic liquid IL, (1-ethyl-3-methylimidazolium methane sulphonate {[
Energy consumption from biofuels against fossil fuels over the past few years has increased. This is due to the availability of these resources for production of different forms of energy, and the environmental benefit in the utilization of these resources. Ethanol fuel production from biomass is a complex process of known challenges in the area of handling, optimizing, and future forecasting. The existence of modelling techniques like artificial intelligence (AI) is, therefore, necessary in the design, handling, and optimization of bioethanol production. The flexibility and high accuracy of artificial neural network (ANN), a machine learning technique, to solve intricate processes is beneficial in modelling pretreatment, fermentation, and conversion stages of a bioethanol production system. This paper reviews various AI techniques in bioethanol production giving emphasis on published articles in the past decade.
Artificial intelligence (AI) has become the future trend for prediction after the data is provided to machine learning. This study uses data analysis to optimize the experiment, find the best-operating conditions, and obtain the maximum glucose concentration for bioethanol production where wet torrefaction (WT) is used to perform biomass pretreatment. Forty-nine (49) sets of data are split into training and test data in the ratio of 7:4. Glucose concentrations from five different feedstocks are trained and predicted using a neural network (NN) and multivariate adaptive regression splines (MARS), followed by a decision tree (DT) to predict the classification of the materials. The predicted NN results are better than MARS, so the NN training is used for the glucose prediction along with the Box-Behnken design (BBD) experiment. The BBD experiment is performed with the parameters of temperature (170, 175, and 180 ?), reaction time (10, 20, and 30 min), and sulfuric acid concentration (0, 0.01, and 0.02 M) for the WT of sorghum distillery residue. By adding the BBD experimental data in NN training, the fit quality of the model is improved to 99.78 \%. The NN model predicts that the highest glucose concentration occurring at the optimal conditions (i.e., 173 ?, 10.5 min, and 0.02 M sulfuric acid) is 15.216 g/L with a relative error of 5.55 \% between the prediction and experiment. These resuts indicate that NN is an appropriate approach to predicting glucose production from biomass WT for bioethanol production. Additionally, the analysis of variance (ANOVA) evaluation shows that the order of the vital parameter for glucose concentration is sulfuric acid, followed by reaction time and temperature.
Background: Expanded polystyrene (EPS), an inexpensive and widely available polymer, has been extensively employed in foam packaging. However, EPS-based foams cause environmental problems because they are nonbiodegradable and little recycled. Therefore, developing foams from renewable sources for application in biodegradable packaging for food and express food delivery is essential to tackle pollution issues of synthetic plastics.Scope and approach: Starch is a renewable, abundant, and low-cost source with thermoplastic properties. For this reason, starch has been used as raw material to develop foams for packaging. This review emphasizes different strategies for improving the mechanical properties, processibility, and antimicrobial activity of starch-based foams and for decreasing their sensitivity to humidity, aiming at employing them as competitive replacement for EPS in packaging. Key findings and conclusions: Starch source, foaming process conditions, plasticizer concentration, fiber type and concentration, and addition of other polymers to form blends can affect the properties and morphology of biodegradable foams, so these factors should be better studied and optimized. Agroindustrial residues have become an interesting alternative to reduce the cost of foams, aiming at a competitive replacement for EPS. Few works have been developed on bioactive starch-based foams. Searching for starch-based foams with antiviral properties against SARS-Cov-2 is also necessary.
The cellulose-rich residues of licorice are usually discarded as waste in many medicine factories, resulting in serious wastage of biomass. In this work, nanocellulose was extracted from licorice residue and the microstructure, particle size, crystallinity, and stability were investigated. The prepared licorice residue nanocellulose (LNC) was incorporated to soy protein isolate (SPI) for the production of eco-friendly nanocomposites. The effects of LNC content (0, 2, 4, 6, and 8 wt\%) on the water sensitivity, mechanical and barrier properties of SPI films were characterized. The results revealed that LNC had a short rod-like structure (100-400 nm in length and 10-35 nm in diameter) and had high stability in aqueous media. LNC had a higher crystallinity degree than licorice residue cellulose. The addition of LNC significantly improved the properties of SPI films, especially at 6 wt\%. At 6 wt\% LNC, tensile strength and contact angle of SPI films increased by 35.4\% and 20.3\%, respectively, and monolayer moisture content, water vapor permeability, and oxygen permeability decreased by 44.4\%, 27.2\%, and 55.5\%, respectively.
The pH and substrate-to-inoculum ratio (S/I) are important parameters in the anaerobic fermentation of agroindustrial residues, and therefore the optimization of these two parameters is needed for a stable, efficient, and sustainable reactor operation. In this work, the parameters pH (5-9) and S/I (0.5-3 gVS gVS(-1)) were optimized to produce biobased volatile fatty acids (VFAs) from hydrothermally pretreated olive mill solid waste (HPOMSW). The response variables evaluated in the Doehlert design were total VFAs concentration (tVFAs) (mg L-1) and amounts (\%) of isobutyric, butyric, isovaleric, and valeric acids on the VFAs profile. The pH was the variable that most influenced the mixed culture fermentation of HPOMSW, proving to be a key parameter in the process. Microbial community analyses of conditions 1 (S/I = 3 gVS gVS(-1) and pH = 7) and 4 (S/I = 1.13 gVS gVS(-1) and pH = 5) showed that Proteobacteria and Firmicutes accounted for more than 87\% of the total microorganisms identified for both conditions. In addition, the second-order model best fitted the experimental data for the VFAs production at the desirable condition (S/I = 3 gVS gVS(-1) and pH = 8).
The process of pyrolysis of beet pulp, a by-product after the extraction of raw sugar from sugar beet, with the addition of defecation lime was studied in a thermobalance coupled with a mass spectrometer. The beet pulp pyrolysis process took place completely at 600 degrees C, and the resulting char, tar and gas were characterized by higher heating values of 23.9, 21.6 and 7.77 MJ/kg, respectively. The addition of the defecation lime to beet pulp caused both an increase in the char production yield and a decrease in the tar production yield. At the same time, the higher heating value of char and tar decreased along with the increase of defecation lime added to the sample. The deconvolution of derivative thermogravimetric (DTG) curves allowed us to identify the basic components of beet pulp, for which the activation energy by isoconversion method was calculated. The 20 wt.\% addition of defecation lime caused an increase of the activation energy by about 18\%. Further increase in the defecation lime content resulted in a reduction of activation energy. At the temperature above 600 degrees C, calcination of calcium carbonate contained in defecation lime occurred. The CO2 produced during calcination process did not cause auto-gasification of char.
An enzymatic method for the carbohydrate hydrolysis of different microalgae biomass cultivated in domestic (DWB) and pig manure (PMWB) wastewaters, at different storage conditions (fresh, freeze-dried and reconstituted), was evaluated. The DWB provided sugars yields between 40 and 63\%, although low xylose yields (< 23.5\%). Approximately 2\% of this biomass was converted to byproducts as succinic, acetic and formic acids. For PMWB, a high fraction of the sugars (up to 87\%) was extracted, but mainly converted into acetic, butyric and formic acids, which was attributed to the bacterial action. In addition, the performance of an alkaline-peroxide pretreatment, conducted for 1 h, 50 degrees C and H2O2 concentrations from 1 to 7.5\% (w/w), was essayed. The hydrolysis of pretreated microalgae supported a wide range of sugars extraction for DWB (55-90\%), and 100\% for PMWB. Nevertheless, a large fraction of these sugars (similar to 30\% for DWB and 100\% for PMWB) was transformed to byproducts. (C) 2016 Elsevier Ltd. All rights reserved.
The present study evaluates the effects of syrup concentrations of natural raisin microflora culture on the characteristics of sourdough and sourdough bread. The original total titratable acidity (TTA) of the starter solutions were between 10.30 and 10.45 mL, after 96 hours of incubation, the TTA of the starter solution increased to 11.30-11.85 mL. The greatest pH decrease and TTA increase occurred in the RS50 group. The microstructure of the control bread was rougher and contained more ungelatinized starch particles than bread made with sourdough. The overall acceptability and flavor of bread made using sourdough with the 150 g/L syrup solution was found to be significantly better than the control bread made using commercial yeast. The experimental results show that using a 150 g/L syrup solution and raisins as a natural starter culture helps to produce better quality bread.
In this study, the influence of alkaline hydrogen peroxide (H2O2) pretreatment of the three different plant sources: Miscanthus giganteus, Sorghum Moench, and Sida hermaphrodita, for biogas production was investigated. The influence of temperature, reaction time, and H2O2 concentration on the efficiency of biomass degradation and on the further methanogenic fermentation were studied. The results obtained after chemical pretreatment indicate that using H2O2 at alkaline conditions leads to the decomposition of three major structures: lignin, hemicellulose, and cellulose. The best results were achieved for the process performed at 25A degrees C for 24 h with the use of a 5 mass \% H2O2 solution. Although the degradation level was very high for all three plant sources, the biogas production from the energy crops pretreated chemically was strongly inhibited by byproducts and the residual oxygen formed after H2O2 decomposition. This fact indicates that alkaline H2O2 pretreatment is a very promising method for plant material degradation for further biogas production, but pretreated biomass must be separated from supernatant before the fermentation process because of the high concentration of inhibitors in the hydrolysates. The best results were obtained for Sida with biogas and methane production of 2.29 Ndm(3) and 1.06 Ndm(3), respectively.
This research examines the acid hydrolysis of Curcuma longa waste, to obtain the hydrolysate containing lactic acid and ethanol fermentative sugars. A central composite design for describing regression equations of variables was used. The selected optimum condition was 4.91\% sulphuric acid, 122.68 C and 50 min using the desirability function under the following conditions: the maximum reducing sugar (RS) yield is within the limited range of the 5-hydroxymethylfurfural (HMF) and furfural concentrations. Under the condition, the obtained solution contained 144 g RS/L, 0.79 g furfural/L and 2.59 g HMF/L and was directly fermented without a detoxification step. The maximum product concentration, average productivity, RS conversion and product yield were 115.36 g/L, 2.88 g/L/h, 89.43\% and 64\% for L-lactic acid; 113.92 g/L, 2.59 g/L/h, 88.31\% and 63.29\% for D-lactic acid; and 55.03 g/L, 1.38 g/L/h, 42.66 and 30.57\%, respectively, for ethanol using a 7-L jar fermenter. (C) 2013 Published by Elsevier Ltd.
In recent years, concerns about a good-quality diet have increased. Food supplements such as prebiotics have great nutritional and health benefits. Within the diverse range of prebiotics, xylooligosaccharides (XOs) show high potential, presenting exceptional properties for the prevention of systemic disorders. XOs can be found in different natural sources; however, their production is limited. Lignocellulosic biomasses present a high potential as a source of raw material for the production of XOs, making the agro-industrial by-products the perfect candidates for production on an industrial scale. However, these biomasses require the application of physicochemical pretreatments to obtain XOs. Different pretreatment methodologies are discussed in terms of increasing the production of XOs and limiting the coproduction of toxic compounds. The advance in new technologies for XOs production could decrease their real cost (USD 25-50/kg) on an industrial scale and would increase the volume of market transactions in the prebiotic sector (USD 4.5 billion). In this sense, new patents and innovations are being strategically developed to expand the use of XOs as daily prebiotics.
As a pulping and bio-refinery by-product with phenolic chemical structure, lignin indicated high potential as natural antioxidant activity, UV blocker, antibacterial and toxic material absorbent properties. Presence of phenolic hydroxyl groups in lignin structure plays the main role of its antioxidant activity. However, lignin antioxidant power can change depending on its other structural features and functional groups like ortho- methoxy groups, -OCH3 groups, the alpha-CH2 groups, the aliphatic carbonyl groups, and the size of pi-conjugated systems. Lignin in mixture with synthetic polymers, improved their thermal stability. Lignin has high UV light absorbing potential in broad-spectrum (UVA, UVB). Adding 1-5\% of lignin into hand cream indicated excellent range of sun protection factor (SPF) with more than 95\% UV light absorption. Lignin also indicated strong UV light protection when applied in different transparent film and protect paint, oil, and varnish from UV degra-dation. Lignosulfonate and other modified lignin including chemically modification, nano-particles and lignin hydrogel indicated high potential as heavy metal absorber.
In this study, lipid-dense post-hydrolysis spent coffee grounds (PHSCG), containing -23 wt\% lipid, was utilized as feedstock in the production of fatty acid methyl esters (FAME) via in-situ (trans)esterification (ISTE). The collected PHSCG were pre-functionalized (-0.86 mmol H+/g dried, lipid-free PHSCG) after sufficient drying of wet residues obtained from the dilute acid hydrolysis (DAH) of spent coffee grounds (SCG). Taguchi method and regression analysis were adopted in the optimization of the ISTE, with temperature, solvent-to-solid ratio (SSR), and reaction time, as the main factors investigated. An optimum yield of 19.47 +/- 2.44 g FAME/100 g PHSCG, corresponding to -96\% conversion, could be achieved during ISTE in a batch reactor system. The ISTE of lipids in PHSCG were carried out without catalyst addition due to the inherent catalytic activity of the prefunctionalized PHSCG. Elemental and FT-IR analyses were conducted to determine the extent of the functionalization. The strong acid density of the material increased 21.5 times upon sufficient drying after DAH. Although, some of the functionalized material were solubilized during ISTE, the post-ISTE residue still had significant a strong acid site, 2.47 times of the native SCG, and exhibited appreciable activity when used as solid acid catalyst for the esterification of oleic acid and methanol while having good stability. The DAH and subsequent drying to induce simultaneous carbonization and sulfonation, may be adopted as a means of generating raw materials for biodiesel production from lipid-containing lignocellulosic residues like SCG.
The objective of this trial was to evaluate the apparent total tract digestibility of nutrients on sheep fed diets containing ammoniated clephantgrass silage plus cocoa meal or palm kernel cake, which partially replaced corn and soybean meal in the concentrate. Eighteen non-castrated Santa Ines sheep averaging 22.6 kg of body weight were assigned to a completely randomized design with a 2 x 3 factorial arrangement of treatments. The experiment lasted 77 days with 14 clays for diet adaptation and three 21 days periods for data and sample collection. Diets were composed by 60\% of forage and 40\% of concentrate. Treatments containing treated (urea) or untreated elephant grass silage plus one the following concentrate mixture: 1) corn and soybean meal, 2) corn, soybean meal and cocoa meal, or 3) corn, soybean meal and palm kernel cake. Ammoniation and replacement of 40\% of corn and soybean meal in the concentrate with cocoa meal or palm kernel cake did not significantly change the dietary digestibility of nutrients. It is recommended the partial replacement of corn and soybean meal with cocoa meal or palm kernel in diets of sheep.
Coproduction of H-2 and volatile fatty acids from sweet sorghum stalks was successfully developed via two-step fermentation process involving alkaline and enzymatic treatment of the residual slurry obtained from the first step fermentation of the raw material. The optimum treatment conditions to obtain the highest yield of the end products included 2\% (w/v) alkali at 120 degrees C for the residual slurry and 32 FPU cellulase per gram of the alkali-treated materials. The two-step fermentation using Clostridium thermosaccharolyticum increased the end product yields of H-2 (6.37 mmol/g-substrate) by 95\%, acetic acid (2.33 g/L) by 97\% and butyric acid (2.36 g/L) by 143\% compared with those obtained in the single step fermentation without any treatment. As a result, the H-2 energy recovery efficiency of the two-step fermentation process with commercially attractive butyric acid as a coproduct reached 10.54\%. These results provide a promising approach for sweet sorghum biorefining.
In the present work, biosorption of copper(II) in the presence of lead(II) ions by native pine cone shell (PCS) was investigated in batch and packed bed reactors. Particularly, it provides new information regarding binary biosorption of metals in continuous flow. The behavior of competitive Cu(II) and Pb(II) biosorption in batch was successfully described by the multicomponent Sips model, obtaining maximum capacities for Cu(II) and Pb(II) of 6.52 mg/g and 17.41 mg/g, respectively. The single-metal biosorption uptake capacities of the biomass for copper and lead were slightly inhibited by the presence of lead and copper, respectively. Pine cone shell removed the target metal ions in the affinity order of Pb(II) > Cu(II) quantified in mass basis. Factors such as covalent index of the metal ions may contribute to this result. In tests carried out in a packed-bed column, the biosorption capacity for Pb(II) (17.85 mg/g) was also higher than copper one (9.38 mg/g), confirming the higher selectivity of the pine cone shell for lead over copper ions in continuous system too. Finally, desorption studies indicated that Cu,Pb-loaded PCS could be easily eluted by 03 M HCl. (C) 2016 Elsevier B.V. All rights reserved.
Ionic liquids (ILs) have emerged as attractive solvents for lignocellulosic biomass pretreatment in the production of biofuels and chemical feedstocks. However, the high cost of ILs is a key deterrent to their practical application. Here, we show that acetate based ILs are effective in dramatically reducing the recalcitrance of corn stover toward enzymatic polysaccharide hydrolysis even at loadings of biomass as high as 50\% by weight. Under these conditions, the IL serves more as a pretreatment additive rather than a true solvent. Pretreatment of corn stover with 1-ethyl-3- methylimidizolium acetate ({[
Factors such as raw materials availability, production capacity, technology, and costs promote the development and feasibility of supply chains. However, some other factors are more than important for supply chain development; they are essential. In the context of biofuel supply chains, water is a crucial factor; nevertheless, scientific research has not yet analyzed how water scarcity can compromise the performance of these supply chains. To address this gap, this research analyzes as a case study a leading company in Mexico that produces and distributes biofuel in the country. Lately, the company has experienced serious production stoppages due to water supply disruptions. This work develops a system dynamics simulation model to evaluate, by means of a sensitivity analysis, the effects of water supply disruption on industrial production and biofuel demand satisfaction in four duration periods: 8, 12, 24, and 48 h. The results indicate that production disruptions due to water scarcity can be avoided by reducing the mash flow that feeds the distillation column as long as the water scarcity period lasts no more than 12 h. Similarly, it was found that demand satisfaction decreases when the scarcity period lasts for 24-48 h, yet demand satisfaction remains stable when water disruption lasts less than 24 h. The findings also indicate that when demand increases by 20\%, it is impossible to fulfill it in any case. Therefore, several scenarios designed to improve demand satisfaction were evaluated.
A main global challenge is finding an alternative material for cement, which is a major source of pollution to the environment because it emits greenhouse gases. Investigators play a significant role in global waste disposal by developing appropriate methods for its effective utilization. Geopolymers are one of the best options for reusing all industrial wastes containing aluminosilicate and the best alternative materials for concrete applications. Waste wood ash (WWA) is used with other waste materials in geopolymer production and is found in pulp and paper, wood-burning industrial facilities, and wood-fired plants. On the other hand, the WWA manufacturing industry necessitates the acquisition of large tracts of land in rural areas, while some industries use incinerators to burn wood waste, which contributes to air pollution, a significant environmental problem. This review paper offers a comprehensive review of the current utilization of WWA with the partial replacement with other mineral materials, such as fly ash, as a base for geopolymer concrete and mortar production. A review of the usage of waste wood ash in the construction sector is offered, and development tendencies are assessed about mechanical, durability, and microstructural characteristics. The impacts of waste wood ash as a pozzolanic base for eco-concreting usages are summarized. According to the findings, incorporating WWA into concrete is useful to sustainable progress and waste reduction as the WWA mostly behaves as a filler in filling action and moderate amounts of WWA offer a fairly higher compressive strength to concrete. A detail study on the source of WWA on concrete mineralogy and properties must be performed to fill the potential research gap.
This study aimed to develop a promising biorefinery technology for the value-added utilization of herb residues by using ionic liquid (IL) assisted by aromatic acid (p-toluenesulfonic acid, TsOH) pretreatment. The result showed that the addition of low concentration of TsOH into IL could effectively deconstruct the recalcitrant intercellular structure of herb residues and rapidly extract the lignin fraction. Under the optimum conditions (79\% IL, 1.0\% TsOH, and 20\% H2O at 130 degrees C and 2 h), the highest cellulose recovery yield of 96.4\%, the lignin removal rate of 79.9\% and ideal saccharification yield of 98.9\% were achieved. Moreover, the main byproduct lignin exhibited comparable yield, high purity, and thermal stability, suggesting the potential application in the conversion of bio-based chemicals and materials. Furthermore, the IL was successfully recycled three times and the recovery rate was at least 95\% each time. High saccharification yields and lignin recovery were maintained during all cycles. The hemicellulose-derived saccharides were the main impurities detected in the recycled IL. Overall, this work presents a novel green pretreatment process that can effectively utilize herb residues.
An experimental investigation on the gasification of corncobs was conducted in an 18 kW pilot-scale fixed bed system for power generation. The main objective was to determine the effect of gasifying corncob mixtures with fines content (particle size below 10 mm) on the performance of the system. To achieve the objective, a 2x 3 factorial arrangement was developed. The analysis considered three resistive loads connected to the generator (4, 8, and 12 kW) and two different size ranges of biomass (one with 100\% of chips within the actual recommended size (10-40 mm)) and the other with a content of 15\% of fine particles (particle size below 10 mm). An increase of 15\% in fine material content in the feedstock and a stable electricity demand close to the rated capacity, significantly increased the temperature of the process and decreased the mean specific fuel consumption - SFC (2.06 kg/kWh at 67\% of rated capacity). H-2 and CO production increased by increasing reactor temperature, reaching concentrations of 16.7\% and 17\% respectively at the higher resistive load (12 kW). Cold gas efficiency varied in the range of 33.7\%-37.0\%, increasing slightly with the blend of fines content and higher applied load. (C) 2019 Elsevier Ltd. All rights reserved.
Energy cane biochar (ECBC) was prepared in a 72 s fast pyrolysis at 425 degrees C in an auger-fed reactor and ground into 250-600 pm diameter particles. This biochar was magnetized by fusing an iron oxide phase to the particles by mixing aqueous biochar suspensions with aqueous Fe3+/Fe2+ solutions, followed by NaOH treatment (MECBC). These biochars were characterized by Raman, FT-IR, X-ray, SEM, SEM-EDX, TEM, EDXRF, pHzpc, elemental analyses, SBET, and magnetic moment determinations. The SUET of energy cane biochar was negligible and increased to 37.13 m(2)/g after Fe3+/Fe2+/NaOH magnetization. The dry biochar contains 18.4\% oxygen. This allows swelling in water and permits sorption inside the solid as well as on its pore surfaces, leading to high capacities at low surface areas. Maximum lead removal occurred at pH 4-5. Sorption isotherms exhibited increasing lead removal (Q, mg/g) as temperature increased for nonmagnetic {[
An organic-inorganic hybrid mesoporous silica material was synthesized by two-step post-grafting method of SBA-15 with 3-aminopropyltrimethoxy-silane (APTES) and thionyl dichloride (SOCl2) activated ethylenediaminetetraacetic acid (EDTA) in sequence and measured by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), elemental analysis (EA), transmission electron microscopy (TEM), nitrogen (N-2) adsorption-desorption analysis and back titration. The material was found having the beneficial properties of mesoporous silica SBA-15 and EDTA. Adsorption potential of the material for Pb (II) removal from aqueous solution was investigated by varying experimental conditions such as pH, contact time and initial metal concentration. The removal efficiency of Pb2+ was high under studied experimental conditions. The adsorption equilibrium could be reached within 20 min and the kinetic data were fitted well by pseudo-second-order and intraparticle diffusion model. The adsorbent exhibited a favorable performance and its maximum adsorption capacity calculated by the Langmuir model was 273.2 mg g(-1). Recycling experiments showed the adsorbent could be regenerated by acid treatment without altering its properties. The chemical states of the elements involved in the adsorption were analyzed by X-ray photoelectron spectroscopy (XPS). The results demonstrated that the adsorption mechanism of the material involved Na Pb ion-exchange and carboxyl group dominated surface complexation. (c) 2012 Elsevier Inc. All rights reserved.
The seed powder of Punica granatum L. in its natural form was evaluated for the removal of two types of basic dyes, crystal violet (CV) and methylene blue (MB), through batch experiments. A number of adsorption variables such as pH (2 - 10), initial concentration (25 -250 mg/L), time (0 - 250 min), and temperature (293 - 323 K) were observed. The studied eco-friendly waste material removed 91.1\% of CV and 83.6\% of MB at neutral pH. The optimum conditions for the experiment were at pH 7, 50 mg/L concentration, 0.2 g dose, 293 K, and 60 min. The maximum Langmuir monolayer adsorption capacities for CV and MB were 434.8 and 99.1 mg/g, respectively. Results exhibited that the adsorption consequences of both the dyes complied with pseudo-second-order kinetics. The critical statistical examination of results confirmed that the data interpreted by Langmuir isotherm. Desorption efficiencies were checked using acetic acid and sodium chloride. The re-adsorption capacities were 85\% and 79\% for CV and MB, respectively, which showed the possibility of reusing the used competent material.
Effects of switchgrass particle sizes (<0.25 mm, 0.5-1.0 mm, and 2.0-4.0 mm) on the effectiveness of H2SO4 and NaOH pretreatments were investigated. As particle size increased, glucan, xylan, and lignin contents in raw switchgrass augmented from 30.32\% to 32.02\%, 18.44\% to 19.03\%, and 14.78\% to 15.33\%, respectively. Glucan and xylan (58.54-60.94\% and 18.55-20.01\%) contents in NaOH pretreated switchgrass and their recoveries (91.95-94.69\% and 47.91-52.31\%) increased. The highest glucan content (55.76\%) and recovery (79.72\%) in H2SO4 pretreated switchgrass were reached by middle particle size. The lowest (59.39\% for H2SO4 and 58.99\% for NaOH) and highest (65.23\% for H2SO4 and 66.15\% for NaOH) CrI values were obtained from middle and small particle sizes, respectively. SEM images and FTIR spectra showed no visible variations in microstructures and chemical bonds among different particle sizes under the same pretreatment conditions. On the basis of pretreated switchgrass, the highest ethanol concentration and efficiency were reached by big particle size for H2SO4 pretreated (7.03 g/L and 49.28\%) switchgrass, while they were achieved by small particle size for NaOH pretreated (11.68 g/L and 72.37\%) switchgrass. The highest ethanol yield based on raw switchgrass was attained by big particle size for untreated (29.54\%), middle particle size for H2SO4 pretreated (30.60\%), and small particle size for NaOH pretreated (62.36\%) switchgrass. These findings indicate that the optimal ethanol conversion performance is the result of the interaction between the pretreatment method and biomass particle size.
Torrefied biomass is a commercial fuel, which is particularly produced from woody biomass via torrefaction and alternative to coal to reduce greenhouse gas emissions in the short term. In this study, torrefaction conditions of cotton stalk were optimised, and the effect of bulk density together with temperature and residence time on process yields and characterisation of torrefied cotton stalk was investigated. Response surface methodology using Box-Behnken design was employed for the design of experiments and optimization. Cotton stalk was torrefied at a temperature between 260 degrees C and 320 degrees C, in 10, 35, and 60 minutes with bulk density of 125, 150, and 175 kgm(-3). Temperature was the most effective parameter for the six responses (higher heating value, carbon content, hydrogen/carbon and oxygen/carbon ratios, mass loss, and energy yield). Besides, temperature/bulk density interaction was found to be significant for all responses whereas residence time/bulk density interaction was effective for process yields. The optimization results showed that more economical torrefied biomass with similar quality of lignite could also be produced under process conditions of 305 degrees C-32 minutes-158 kgm(-3). At this point, higher heating value and carbon content of product were calculated as 19.7 MJ kg(-1) and 64\%, respectively.
This study aims at optimizing the adsorption of heavy metal ions onto banana peel derived activated carbon (AC) using response surface methodology (RSM) involving central composite design (CCD). The cheap, non-toxic and locally available banana peel was subjected to carbonization and subsequently KOHactivation to produce the porous AC, which was then characterized by SEM and FTIR analyses. In RSM study, the individual and interactive effects of three critical variables including heavy metal ion concentration, pH of solution and AC dosage on the adsorption capacity were optimized. The maximum adsorption capacity appeared to follow the order: Cu2+ (14.3 mg/g) < Ni2+ (27.4 mg/g) < Pb2+ (34.5 mg/g) that agreed well with the verification experiments, revealing the reliability and suitability of the optimization approach. In addition, the results of isotherm study show that the Langmuir model can be used to best describe the adsorption behavior of Cu2+ and Ni2+ onto the banana peel derived activated carbon. (C) 2016 Elsevier B.V. All rights reserved.
Cellulose in nanostructures was successfully isolated from empty fruit bunch biomass via a novel one-pot oxidative-hydrolysis technique. The physicochemical properties of nanocellulose prepared via one pot process have shown comparable characteristics as products isolated via conventional multistep purification approach (namely dewaxing, chlorite bleaching process, alkalization, and acid hydrolysis). The chemical composition study indicated that the one-pot oxidative-hydrolysis process successfully extracted cellulose (91.0\%), with the remaining minority being hemicellulose and lignin (similar to 6\%) in the final product. Crystallinity profile of one-pot treated product (80.3\%) was higher than that of multistep isolated nanocellulose (75.4\%), which indicated that the disorder region (amorphous) in cellulose fibers was successfully removed. In additional to that, the morphology study demonstrated that nanocellulose prepared by one-pot process rendered spider-web-like network nanostructure, with an average diameter of fibers at a range of 51.6 +/- 15.4 nm. The nanocellulose product showed high thermal stability (320 degrees C), which was ready for nanocomposite application. One-pot oxidative-hydrolysis technique is a simple and versatile route for the preparation of nanocellulose from complex biomass within 90 degrees C and 6 h period, with minimum wastewater as compared to the multistep process. (C) 2016 Elsevier Ltd. All rights reserved.
Aim: To produce high laccase activities from the white-rot fungus Fomes fomentarius. Methods and Results: Different culturing methods, viz, cell immobilization on stainless steel sponges and plastic material and solid-state fermentation (SSF) using wheat bran as substrate were used for laccase production by the white-rot fungus F. fomentarius. The SSF study expresses the highest laccase activities, nearly to 6400 U l(-1) after 13 days of laboratory flasks cultivation. When the wheat bran medium was supplemented with 2 mmol l(-1) copper sulfate, laccase activity increased by threefold in comparison to control cultures, reaching 27 864 U l(-1). With the medium thus optimized, further experiments were performed in a 3 l fixed-bed bioreactor (working volume 1.5 l) leading to a laccase activity of about 6230 U l(-1) on day 13. Conclusions: The results obtained clearly showed the superiority of wheat bran for laccase production over stainless steel sponges and plastic material. Supplementing the wheat bran solid medium with 2 mmol l(-1) copper sulfate allowed obtaining high activities at flask scale. The system was scaled to fixed-bed laboratory reactor. Significance and Impact of the Study: The high enzyme production along with the low-cost of the substrate, showed the suitability of the system F. fomentarius - SSF for industrial purposes.
Elephant grass is a promising lignocellulosic biomass for use in biorefineries due to its composition and productivity. To enhance the use of elephant grass (Pennisetum purpureum Schum.) as a raw material for the production of fermentable sugars, two different hydrothermal pretreatment methodologies were studied, using liquid hot water and saturated steam. Hydrothermal pretreatments were carried out according to a central composite design, varying the time (1-12 min) and temperature (170-220 degrees C) of the processes. Solid fractions were subjected to hydrolysis using the enzymatic complex produced by Pennicilium echinulatum. Both methodologies tested showed a strong positive linear correlation between the severity factor {[
Purpose In this study, the tri-bological behaviour of the un-coated and diamond coated tungsten carbide was evaluated using the pin-on-disc test rig. The same was also tested on a lathe machine tool. This paper aims to compare the tri-bological behaviour of coated tungsten carbide pin with un-coated tungsten carbide pin it also correlates the wear obtained from the two machines used. Design/methodology/approach Experiments were performed using L8 orthogonal array and results obtained on a pin-on-disc test rig under dry sliding process were optimized through a modern optimization technique i.e. genetic algorithm (GA). The response surface methodology model (L8 orthogonal array) formed the basis for the development of the GA model, which defines the conditions of minimum wear, minimum coefficient of friction and minimum surface roughness for the sliding process of the pin-on-disc test rig. Findings Implementation of the heuristic approach for optimization of input parameters for the combination of tool material used for the turning process. The initial approach involves tri-bological testing considering the same combination. The set of experiments further performed, inferred that the results were similar and that the diamond coating enhances the life of the tool. Originality/value Successfully synthesized the diamond coating on tungsten carbide tool material. Implantation of the heuristic approach, i.e. GA to tri-bological tests to identify the optimized level of input variables. Experimentation involves the tri-bological testing whose results were confirmed through performing experiments on the lathe machine tool.
This study evaluated the production of cellulolytic enzymes from different agricultural residues. The crude enzyme extract produced was characterized and applied for saccharification of some agricultural residues. Maximum cellulolytic activities were obtained using soybean hulls. All enzymatic activities were highly stable at 40 degrees C at a pH range of 4.5-5.5. For stability at low temperatures, the enzyme extract was stored at freezing temperature and cooling for about 290 days without major loss of activity. The K-m values found for total cellulase (FPase), endoglucanase (CMCase), and xylanase were 19.73mgml(-1), 0.65mgml(-1), and 22.64mgml(-1), respectively, and V-max values were 0.82molmin(-1)mg(-1), 0.62molmin(-1)mg(-1), and 104.17molmin(-1)mg(-1) to cellulose, carboxymethyl cellulose, and xylan, respectively. In the saccharification tests, the total amount of total reducing sugars (TRS) released from 1g of soybean hulls catalyzed by the enzymes present in the crude enzyme extract was 0.16gg(-1) dry substrate.
Microalgae are a prime source of third generation biofuels. Many thermochemical processes can be applied to convert them into fuels and other valuable products. However, some types of microalgae are characterized by very high moisture and ash contents, thereby causing several problems in further conversion processes. This study presents wet torrefaction (WT) as a promising pretreatment method to overcome the aforementioned drawbacks coupled with microalgal biomass. For this purpose, a microwave-assisted heating system was used for WT of microalga Chlorella vulgaris ESP-31 at different reaction temperatures (160, 170, and 180 degrees C) and durations (5, 10, and 30 min). The results show several improvements in the fuel properties of the microalga after WT such as increased calorific value and hydrophobicity as well as reduced ash content. A correlation in terms of elemental analysis can be adopted to predict the higher heating value of the torrefied microalga. The structure analysis by Fourier transform infrared (FT-IR) spectroscopy reveals that the carbohydrate content in the torrefied microalgae is lowered, whereas their protein and lipid contents are increased if the WT extent is not severe. However, the protein and lipid contents are reduced significantly at more severe WT conditions. The thermogravimetric analysis shows that the torrefied microalgae have lower ignition temperatures but higher burnout temperatures than the raw microalga, revealing significant impact of WT on the combustion reactivity of the microalga. Overall, the calorific value of the microalga can be intensified up to 21\%, and at least 61.5\% of energy in the biomass is retained after WT. (C) 2016 Elsevier Ltd. All rights reserved.
The high lignin content in the unripe coconut fiber limits the use of this biomass as a cellulose nanocrystal source compared to other cellulose-rich materials. The aim of this study was to obtain lignin and biomethane, and evaluate different approaches for extracting cellulose nanocrystal from unripe coconut coir fiber. The environmental evaluation of these approaches is presented in the second part of this paper. Lignin was extracted by acetosolv pulping and cellulose by alkaline hydrogen peroxide bleaching respectively. Were evaluated the biochemical methane potential of the effluents resulting from acetosolv pulping as well as the lignin concentration. Cellulose nanocrystals were prepared from cellulose pulp via four methods: acidic hydrolysis with high acid concentration, acidic hydrolysis with low acid concentration, ammonium persulfate oxidation, and high-power ultrasound. The cellulose nanocrystals were analyzed by FTIR spectroscopy, X-ray diffraction, transmission electron microscopy, and TG analysis. Using these methods, the whole coconut fiber could be used to produce cellulose nanocrystals and lignin. Among the proposed methods, high-power ultrasound showed the highest efficiency in cellulose nanocrystal extraction. (C) 2016 Elsevier B.V. All rights reserved.
Utilizing lignocellulosic biomass wastes to produce bioproducts is essential to address the reliance on depleting fossil fuels. However, lignin is often treated as a low-value-added component in lignocellulosic wastes. Valorization of lignin into value-added products is crucial to improve the economic competitiveness of lignocellulosic biorefinery. Monomers obtained from lignin depolymerization could be upgraded into fuel-related products. However, lignins obtained from conventional methods are low in 8-O-4 content and, therefore, unsuitable for monomer production. Recent literature has demonstrated that lignins extracted with alcohol-based solvents exhibit preserved structures with high 8-O-4 content. This review discusses the recent advances in utilizing alcohols to extract 8-O-4-rich lignin, where discussion based on different alcohol groups is considered. Emerging strategies in employing alcohols for 8-O-4-rich lignin extraction, including alcohol-based deep eutectic solvent, flow-through fractionation, and microwave-assisted fractionation, are reviewed. Finally, strategies for recycling or utilizing the spent alcohol solvents are also discussed.
Waste paper holds great potential as a substrate for the microbial production of bioplastic (Poly-3-hydroxybutyrate (PHB)). This study aimed to produce PHB by utilizing office paper as a substrate using Cupriavidus necator through batch and fed-batch simultaneous saccharification and fermentation (SSF) approach. For the batch experiment, different loadings of shredded office paper (3, 5 and 10\%) with two different pretreatments H2O2 (OPH) and H2O2 and Triton X-100 (OPTH) were carried out. For the fed-batch experiment, paper loading started with 3\% and two more additions were made at 36 and 84 h. Both experiments were conducted at 30 degrees C, 200 rpm and pH 7 using 55.5 FPU/g of cellulase and 37.5 CBU/g of beta-glucosidase with a fixed amount of nitrogen source. High PHB yield was observed with OPH in all loadings, though the OPHT showed a better hydrolysis. Maximum PHB yield (4.27 g/L) was achieved with 10\% OP on the sixth day of fermentation in batch SSF. Whereas, maximum PHB yield (4.19 g/L) was obtained within a shorter time (66 h)with OPH in the fed-batch experiment. The extracted PHB showed well-matched characteristic features to the standard PHB. Finally, this study proves the feasibility of employing the SSF process for PHB production using waste paper as an alternative approach to overcome the shortcoming of the separate hydrolysis and fermentation (SHF) process.
The production of durable biomass pellets have always been challenged by several factors including the lack of understanding of the mechanism involved in how particles combine to form pellets under standard conditions of the pellet press. This is because contributing factors span several molecular, microscopic, and even nanoscopic levels as biomass undergoes pelleting. The characteristics of the bonds formed between the combining particles and their relevance to the quality of pellets remains vague, no matter how quality is defined. However, even though few researchers have attempted to explain the mechanism of bonding in densified biomass pellets using different theories, none of their hypotheses supports particle bonding from a structural chemistry perspective. There are still no clear explanations which consider the role of molecular structure and the interactions of substances as milled biomass undergo pelleting. In view of these arguments therefore, this review presents an indepth analysis of a structural chemistry perspective of the mechanism of bonding and the use of additives in densified biomass pellets and helps identify research areas needed to facilitate better understanding of bonding in densified biomass pellets. The status of current research in biomass pelleting, types of materials suitable as additives and their structural characteristics, as well as the current technical specifications of using additives are also discussed.
The present study demonstrates the application of alkali treatment coupled with steam for the extraction of xylan followed by its enzymatic hydrolysis for the production of xylooligosaccharide (XOS) from coconut husk. The chemical analysis of the husk revealed the presence of hemicelluloses, along with cellulose, lignin and ash demonstrating its suitability for XOS extraction. Application of 20\% of NaOH coupled with steam treatment for 60min enabled the fractionation of approximately 93\% xylan from the husk. Response surface methodology was employed to optimize the different variables i.e. enzyme concentration, pH, temperature and time for the extraction of XOS from xylan, wherein, enzyme concentration and temperature were the influential variables affecting xylose yield and enzyme concentration, temperature, time and pH were influential variables affecting xylobiose yield significantly. FTIR analysis of the husk also confirmed the presence of hemicelluloses, whereas, the presence of xylan and XOSmix was also confirmed in the extracted mass. In nutshell, the present study was successful in establishing the suitability of coconut husk for extraction of xylan and XOS which can be further used as a prebiotic.
Cellulosic biomass is an abundant renewable resource that is suitable as a filler for commercial polyesters to reduce the cost of biodegradable plastics. However, the limited miscibility of lignocelluloses and polyesters results in the poor tensile properties and competitiveness of the composites. Herein, wood-based biodegradable composite films with applicable mechanical properties were directly fabricated by blending chemically modified wood meal with poly(butylene adipate-co- terephthalate) (PBAT) matrix. Wood meal was efficiently dissolved and modified by a rapid (1 h) homogeneous esterification reaction with lauryl chloride in an ionic liquid under a microwave-assisted condition. The esterified wood offered good thermoplastic and hydrophobic characteristics and process-ability, and it can be better melt-blended with PBAT. The prepared wood-based PBAT composite films exhibited acceptable tensile properties (17.0 MPa and 452.7\%) under a high addition ratio (40\%) of esterified wood. The characterizations of chemical structure, morphology, and thermal properties of the composites revealed that the uniform dispersion and excellent compatibility between esterified wood and PBAT boosted the final mechanical properties of the composite films. This work offers a rapid route to produce economically competitive biodegradable composite films.
There is growing scientific and industrial interest in obtaining useful substances by fractionating lignocellulosic biomass from non-food plant crops for use by the bioenergy industry. The primary goals are to ensure process sustainability and to comply with the principles of circular economy. In this work, we optimized energy production from Elephant grass by previously using cold alkaline extraction to remove its hemicellulose fraction. Elephant grass contains a high proportion of lignin (20\%) and hemicelluloses (27.4\%), and therefore is an excellent alternative to wood materials for energy production by direct burning. Energy production was optimized to identify the best operating conditions among those tested, namely: alkali concentrations of 80-120 g NaOH L-1, temperatures of 20-40 degrees C, and treatment times of 30-90 min. Using the optimum conditions thus established (viz., 100 g NaOH L-1, 30 degrees C, and 30 min) raised the high heating value (HHV) to 19.151 MJ kg(-1) (i.e., by 4\% relative to the starting material). Also, it allowed the content in elemental C to be preserved, that in H increased by 4.86\% and, more environmentally significant, most sulphur (46.9\%) to be removed from the solid phase upon treatment. Cold alkaline extraction of the raw material additionally enabled relatively selective separation of the hemicellulose fraction from the cellulose and lignin fractions. Thus, 30.1\% of all hemicellulose was dissolved in the treatment liquor and made valorizable while 93.0\% of cellulose and 82.1\% of lignin present in the raw material remained in the solid phase.
The adsorption of Cu (II) from aqueous solutions using coconut shell modified powder was investigated in batch experiments. The surface charge of the adsorbent was determined. The points of zero charge (PZC) of the adsorbents (pH(PZC)) were 4.5, 2.0, and 2.0 to raw coconut (RC), raw coconut alkalized (RCA), and coconut shell modified with tannic acid (TCA) adsorbent, respectively. Batch experiments were performed under kinetic and equilibrium conditions. The kinetic data were analyzed using a pseudo second-order, and Elovich equation. Adsorption equilibrium data were investigated using the Langmiur, Freundlich, Temkin, and Dubinin-Raduschevich (D-R) isotherm models. It has been found that chemically modified coconut shell (TAC) affected performance when compared with unmodified coconut shell (RC). Kinetic studies showed that the adsorption followed a pseudo-second-order rate model. Biosorption kinetics of Cu(II) on the adsorbent TCA was rapid such that almost 90\% of Cu(II) were adsorbed within 80 min. (C) 2014 Wiley Periodicals, Inc.
Apple pomace (AP), before and after chemical modification (CM), was assessed for the removal of cadmium (Cd2+) ions from aqueous solution by equilibrium, kinetics, and thermodynamics studies. The chemical modification of AP was done with succinic anhydride by a simple ring opening mechanism for providing a large surface area for cadmium adsorption. The surface area of chemically modified apple pomace (CMAP) increased about 18\% after the treatment. The amount of CMAP required for cadmium removal was 50 times less than the unmodified AP. The Langmuir adsorption isotherm equation was found to be more suitable for the AP and CMAP adsorption experimental data with a correlation coefficient of r(2) = 0.99 than was the Freundlich isotherm. The FTIR spectra of CMAP, with or without cadmium loading, indicated that ester (-C00), carboxyl (-CO), and amine (-NH2) groups were involved in the cadmium adsorption mechanism. The adsorption of cadmium ions onto AP and CMAP followed pseudo-second-order kinetics. The Delta G degrees value, at different temperatures, was calculated by applying the Van't Hoff equation and found to be negative, indicating that the reaction is spontaneous in nature. The value of, Delta H degrees indicated that the adsorption was exothermic (-6.93 KJ mol(-1)) and endothermic (3.171 KJ mol(-1)) for AP and CMAP, respectively. CMAP could be reutilized for up to three cycles with a removal efficiency of 76.6\%, while AP efficiency lessened significantly after a single cycle. (C) 2014 Elsevier Ltd. All rights reserved.
The use of biomass has been emerging as a worldwide trend. Although biomass is a renewable energy source, the disposal of generated by-products is an issue. A material with great potential for this purpose is oat husk. Nevertheless, no study has systematically investigated the influence of burning temperature on the characteristics of oat husk ash (OHA) and the use of this by-product as a supplementary cementitious material (SCM) and its influence on the properties in the fresh and hardened state of cementitious materials. The results showed that replacing up to 20 \% of Portland cement with OHA burned at a temperature of 600 degrees C without compromising the cement pastes 7-d and 28-d compressive strength. The environmental analysis demonstrated the potential of oat husk as biomass and similar to 24 \% reductions in the eco-efficiency index of the composite matrices with 20 wt\% OHA. Thus, this work identified the technical and environmental potential for the use of OHA as SCM for the production of sustainable cement-based materials.
Interface optimisation for continuous hemp reinforcements in epoxy resin is a current challenge for the development of biocomposites. A chemical treatment based on hydrogen peroxide and a physical one using a non-thermal plasma have been tested to optimise interface adhesion, by varying several parameters. FTIR analysis and FE-SEM observations have shown the effects of the treatments on chemical and morphological aspects of the treated yarns. Tensile tests on hemp yarns have allowed the selection of the treatment parameters leading to the best strength. Fragmentation tests results showed that the two treatments lead to a decrease in the fragment lengths and thus, an enhancement of the Interfacial Shear Strength (IFSS) values in comparison with the untreated yarn. This is confirmed by the micro-CT observations of the debonding lengths in the vicinity of each yarn fragment extremity. Finally, the plasma treated samples exhibit a better interface adhesion quality (IFSS = 44.7 +/- 4 MPa) than the chemically treated ones (IFSS = 24.2 +/- 4 MPa), which are better than the non-treated ones (IFSS = 13.5 +/- 4 MPa).
The increasing concerns about natural-resource depletion and environmental degradation have resulted in developing ``green{''
Foams composed of cassava starch, peanut skin, and glycerol were developed by thermal expansion process. A constrained mixture design was applied to evaluate the effect of components on flexural mechanical properties and water absorption capacity (WAC). The interaction between cassava starch and peanut skin exhibited a significant antagonistic effect in WAC. Effects of the concentration of cassava starch, glycerol and the interactions between cassava starch-glycerol and peanut skin-glycerol were significant to mechanical properties. Desirability function was applied to optimize the formulation in order to obtain less hydrophilic, more flexible and more resistant foams. Optimized formulation consisted of 23.71\% (w/w) peanut skin and 12.68\% (w/w) glycerol, based on solids content (cassava starch+peanut skin). Optimized foam showed experimental values similar to those predicted, validating the fitted models for defined constraints. This foam showed an important improvement in hydrophilicity indicated by a decrease in WAC, compared to cassava starch-based foams without peanut skin.
Deep eutectic solvents (DESs) are green chemicals that have the potential to replace traditional solvents in chemical reactions. In this study, urea-LiCl DES was used successfully as a reaction medium in the anionic functionalization of wood cellulose with succinic anhydride. The effects of reaction temperature and time on the carboxyl content and yield were evaluated. The analyses of the degree of polymerization and crystallinity revealed that the DES was a nondegrading and nondissolving reaction medium. Three samples with the highest carboxyl contents were further nanofibrillated with a microfluidizer to diameters of 2-7 nm, as observed by atomic force microscopy. Samples treated at 70-80 degrees C for 2 h gave the best outcome and resulted in highly viscose and transparent gels. The sample treated at 90 degrees C contained larger nanoparticles and larger aggregates owing to the occurrence of possible side reactions but resulted in better thermal stability.
Trichoderma harzianum IOC-3844 secretes high levels of cellulolytic-active enzymes and is therefore a promising strain for use in biotechnological applications in second-generation bioethanol production. However, the T. harzianum biomass degradation mechanism has not been well explored at the genetic level. The present work investigates six genomic regions (similar to 150 kbp each) in this fungus that are enriched with genes related to biomass conversion. A BAC library consisting of 5,760 clones was constructed, with an average insert length of 90 kbp. The assembled BAC sequences revealed 232 predicted genes, 31.5\% of which were related to catabolic pathways, including those involved in biomass degradation. An expression profile analysis based on RNA-Seq data demonstrated that putative regulatory elements, such as membrane transport proteins and transcription factors, are located in the same genomic regions as genes related to carbohydrate metabolism and exhibit similar expression profiles. Thus, we demonstrate a rapid and efficient tool that focuses on specific genomic regions by combining a BAC library with transcriptomic data. This is the first BAC-based structural genomic study of the cellulolytic fungus T. harzianum, and its findings provide new perspectives regarding the use of this species in biomass degradation processes.
The present study investigated the production of xylooligosaccharides (XOS) from the xylans extracted from maize straws (XMSs) using the fed-batch enzymatic hydrolysis strategy (FBEH). When fed 300 mL of the fresh XMSs with 2 \% of the substrate loading and 12 U/g of the enzyme activity at the enzymatic hydrolysis time of 7 h, the yield of XOS was obtained to be 0.67 g/g of XMSs. Characterization analysis indicated that XOS contained typical molecular groups and side chains of oligosaccharides and was mainly composed of xylobiose, xylotriose and xylose. Furthermore, XOS exhibited strong antioxidant capacity in vitro and had a significant inhibition effect on HepG2 cells, indicating that XOS might be potentially used as natural antioxidants and anticancer additives in food or pharmaceutical industry.
Since large amounts of pineapple leaves are abandoned after harvest in agricultural areas, the possibility of developing value-added products from them is of interest. In this work, cellulose fiber was extracted from pineapple leaves and modified with ethylenediaminetetraacetic acid (EDTA) and carboxymethyl (CM) groups to produce Cell-EDTA and Cell-CM, respectively, which were then used as heavy metal ion adsorbents. A solution of either lead ion (Pb2+) or cadmium ion (Cd2+) was used as wastewater for the purpose of studying adsorption efficiencies. The adsorption efficiencies of Cell-EDTA and Cell-CM were significantly higher than those of the unmodified cellulose in the pH range 1-7. Maximum adsorptions toward Pb2+ and Cd2+ were, for Cell-EDTA, 41.2 and 33.2 mg g(-1), respectively, and, for Cell-CM, 63.4 and 23.0 mg g(-1) respectively. The adsorption behaviors of Cell-CM for Pb(2+ )and Cd2+ fitted well with a pseudo-first-order model, but those of Cell-EDTA for Pb2+ and Cd2+ fitted well with a pseudo-second-order model. All of the adsorption behaviors could be described using the Langmuir adsorption isotherm. Desorption studies of Pb2+ and Cd2+ on both adsorbents using 1 M HCl suggested that regenerability of Cell-EDTA was, for both adsorbates, better than that of Cell-CM. Moreover, adsorption measurements in a mixture of Pb2+ and Cd2+ at various ratios showed that for both adsorbents the adsorption of Pb2+ was higher than that of Cd2+ while the adsorption selectivity for Pb2+ of Cell-CM was greater than that of Cell-EDTA. This study showed that the modified cellulosic adsorbents made from pineapple leaves were able to efficiently adsorb metal ions.
This study describes the chemical modification of chitosan to produce a novel bifunctionalized adsorbent material (C4) for the removal of Cu2+ and oxyanions of Cr6+ from a single aqueous solution. The chemical modifications allowed C4 to be insoluble under acidic conditions, improving the chemical properties of the modified chitosan in aqueous solution. C4 adsorbent was synthesized by reaction of the amino group of chitosan with 2-pyridinecarboxaldehyde, a reduction of imine group, followed by esterification with EDTA dianhydride (EDTAD). C4 was characterized by solid-state C-13 nuclear magnetic resonance, infrared spectroscopy, and elemental analysis. The adsorption studies of Cu2+ and oxyanions of Cr6+ in a batch mode were evaluated as a function of the contact time (kinetics), solution pH, and initial metal ion concentration. The maximum adsorption capacities (Q(max)) of C4 for the adsorption of Cu2+ (pH 5.5) and Cr6+ (pH 2.0) were 2.60 and 3.50 mmol/g, respectively. The reusability of the recovered C4 adsorbent was also evaluated.
Green macroalgae are an abundant and undervalued biomass with a specific cell wall structure. In this context, different pretreatments, namely ethanol organosolv (Org), alkaline, liquid hot water (LHW), and ionic liquid (IL) pretreatments, were applied to the green macroalgae Ulva lactuca biomass and then evaluated. Their effects on chemical composition, biomass crystallinity, enzymatic digestibility, and theoretical ethanol potential were studied. The chemical composition analysis showed that the Org and LHW pretreatments allowed the highest glucan recovery (80.8 +/- 3.6 and 62.9 +/- 4.4 g/100 g DM, respectively) with ulvan (80.0 and 99.1\%) and hemicellulose (55.0 and 42.3\%) removal. These findings were in agreement with both thermogravimetric analysis and scanning electron microscopy results that confirm significant structural changes of the pretreated biomasses. It was found that the employed pretreatments did not significantly affect the cellulose crystallinity; however, they both increased the whole crystallinity and the enzymatic digestibility. This later reached 97.5\% in the case of LHW pretreatment. Our results showed high efficiency saccharification of Ulva lactuca biomass that will constitute the key step of the implementation of a biorefinery process.
The biochemical methane potential (BMP) assays were used as a tool to investigate methane potential of chicken manure (CM) and three co-substrates (chicken processing waste, Miscanthus and seagrass) in mono-digestion and co-digestion studies for selecting regional biomass in a bid to support the expansion of a full-scale biogas plant. Two types of kinetic models (first order and modified Gompertz models) were also applied to study the kinetics of the degradation process. The results show that all feedstock were converted to methane. The experimental methane production of chicken processing Waste (CPW) and CM decreased about 27-35\% compared to calculated methane production. However, the methane production rate/hydrolysis rates of mono digestion of chicken processing waste and co-digestion with CM were above 2 times quicker under the inoculum to substrate (VS) ratio of 6 than that at the I/S ratio of 2 and 4. Miscanthus co-digestion effect was influenced by its composition and seagrass (SG) showed synergetic effect evidenced by high methane yield (which was 11-34\% higher than the yield achieved from calculated BMP). (C) 2016 Elsevier B.V. All rights reserved.
Advancement in industrial biotechnology offers potential opportunities for economic utilization of agro-industrial biomass such as kenaf (Hibiscus cannabinus) for the production of value-added products. This work was conducted to evaluate an enzymatic hydrolysis of kenaf stem (that has been pretreated) for xylooligosaccharides (XOS) production. Pretreated kenaf stems were subjected to two enzymatic hydrolysis approaches which are single xylanase (Xyn2) and a mixture of xylanase:arabinofuranosidase (Xyn2:AnabfA). Central Composite Design was used to optimize the enzymatic hydrolysis conditions on the pretreated kenaf stem to achieve maximum hemicellulose conversion. Under the optimized hydrolysis conditions, hemicellulose conversion (95.03\%) with the highest XOS yield of 351.46 mg/g was achieved at 40 degrees C (pH 4.0) after 48 h incubation with Xyn2:AnabfA ratio of 400 U:10 U. Xylobiose (135.42 mg/g) is the main XOS product with xylotriose (102.04 mg/g) being the second highest. The high production of XOS yield from the pretreated kenaf stem demonstrated the biotechnological potential of the kenaf in the future. (C) 2015 Elsevier B.V. All rights reserved.
Yeast immobilization offers operational advantages such as high cell concentration, and some drawbacks related to cell leaking and restricted mass transfer inside particles. The influence of bead size, chitosan, bead charge, volume of liquid media, and the use of corncob hydrolyzates and vinasses as culture medium were analyzed on xylitol production by Debaryomyces hansenii immobilized in alginate beads. The results showed a profuse growth of free cells, accounting 75-95\% of total biomass, but electron micrographs revealed the generation of a dense biofilm with hyphal morphology at the bead surface and a very low intraparticular growth. Xylitol production was not affected by the size of particle; however chitosan had a negative effect. The use of corn cob as carbon source and twofold diluted vinasses as economic nutrients incremented xylitol concentration to 13.7 g L-1 (Y-P/S = 0.56 g g(-1); Q(P) = 0.29 g L-1 h(-1)). The best conditions corresponded to high bead charges and intermediate liquid volumes (44 g Na-alginate and 110 mL liquid medium). These results showed the feasibility of employing these cheap substrates, reflected the importance of the microaerobical conditions, and pointed to the favorable effect of cell immobilization on the metabolism of xylitol production. (C) 2013 Elsevier Ltd. All rights reserved.
Biohydrogen production from waste lignocellulosic biomass serves the dual purpose of converting waste into valuable products and alleviates waste disposal issues. In this study, waste date seeds were valorized for biohydrogen production via consolidated bioprocessing by Clostridium thermocellum ATCC 27405. Effect of various surfactants (PEG1000, surfactin, Triton X-100) and sodium carbonate (buffering agent) on biohydrogen production from the acid pre-treated substrate was examined. Among the various surfactants, addition of Triton X-100 resulted in the maximum biohydrogen yield of 103.97 mmol/L at an optimal dosage of 0.75\% w/v. Triton X-100 supplementation favoured the production of ethanol and acetate as co-metabolites than butyrate. Addition of Na2CO3 to date seed fermentation medium at a concentration of 15 mM enhanced the biohydrogen production by 33.16\%. Also, Na2CO3 buffering supported the glycolytic pathway and subsequent ethanol production than acetate/butyrate formation. Combined effect of the optimal dosages of Triton X-100 and Na2CO3 resulted in high hydrogen productivity up to 72 h (0.443 mmol/g h of H-2) with a total increase in hydrogen yield of 40.6\% at the end of 168 h, as compared to fermentation supplemented with Triton X-100 alone. Further analysis revealed that the combined effects of the additives resulted in better substrate degradation, favourable pH window and cell growth promotion which ensured enhanced hydrogen productivity and yield. Thus, the study highlights a novel stimulatory approach for enhanced biohydrogen production from a new substrate. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
The aim of this study was to investigate the pozzolanic effect (PE) and filler effect (FE) of rice husk ash (RHA) on the mechanical properties and microstructure of brick aggregate concrete (BAC). For this, concrete cylinders (100 mm x 200 mm) were prepared with 0-25\% RHA with water-to-binder ratios of 0.50 at a constant mix-ratio of 1:1.5:3 and cured in water. Test results revealed that the mean particle size of RHA decreases with increasing grinding time. The compressive strength (f(c)(')) of BAC due to filler effect are 58.56-94.62\% less compared to the pozzolanic effect of RHA for the 10\%-25\% replacement of cement. Meanwhile, the 15\% RHA showed the maximum f(c)(') of BAC due to pozzolanic effect of RHA. The tensile strength (f(sp)) and flexural strength (f(r)) of BAC due to pozzolanic effect are 60\%-150\% and 25\%-150\% higher than that of filler effect of RHA for the 10\%-25\% replacement of cement respectively. The modulus of elasticity (E-c) and Poisson's ratio (v) of BAC due to pozzolanic effect are 2\%-29\% and 27\%-43\% greater than that of filler effect of RHA for the 10\%-25\% replacement of cement respectively. BAC with 10-20\% RHA shows a dense and homogeneous microstructure. Therefore, inclusion of RHA as a partial replacement of cement possesses a significant pozzolanic effect than the filler effect on the mechanical properties and microstructure of BAC.
Billions of tons of agro-industrial residues are produced worldwide. This is associated with the risk of pollution as well as management and economic problems. Simultaneously, non-edible portions of many crops are rich in bioactive compounds with valuable properties. For this reason, developing various methods for utilizing agro-industrial residues as a source of high-value by-products is very important. The main objective of the paper is a review of the newest studies on biologically active compounds included in non-edible parts of crops with the highest amount of waste generated annually in the world. The review also provides the newest data on the chemical and biological properties, as well as the potential application of phytochemicals from such waste. The review shows that, in 2020, there were above 6 billion tonnes of residues only from the most popular crops. The greatest amount is generated during sugar, oil, and flour production. All described residues contain valuable phytochemicals that exhibit antioxidant, antimicrobial and very often anti-cancer activity. Many studies show interesting applications, mainly in pharmaceuticals and food production, but also in agriculture and wastewater remediation, as well as metal and steel industries.
The valorization of agroindustrial wastes has drawn attention, since there is an increasing demand for energy aligned with obtaining bioproducts with higher added-value. In this regard, the residues generated during cassava processing are practically unexplored materials with enormous potential for bioconversion. Cassava peel is a lignocellulosic material that can be treated to remove components such as lignin and starch in order to produce hemicellulosic-based compounds. Different classical pretreatments can be used on cassava peel, in particular alkaline, acidic and hydrothermal, and modern ones such as ultrasonic, microwave and steam explosion. In addition, environmentally friendly techniques such as non-thermal plasma and ionic liquids are promising pretreatments. In general, pretreatments are used to modify the lignocellulosic chemical structure of wood biomass, i.e., physical, chemical, and biological pretreatments change the structure of lignin by breaking its chemical bonds, exposing the internal content (cellulose and hemicellulose), making it possible to obtain hemicellulosic-based bioproducts such as xylooligosaccharides (XOS). XOS are prebiotics that can be obtained from xylan-rich sources such as cassava peels and other biomasses. In this context, this review aims to critically discussed the current production of XOS based on cassava peels, including the most promising and efficient pretreatments applied on lignocellulosic wastes to obtain higher value-added bioproducts. In addition, it addresses the challenges on the change of lignocellulosic chemical structures of different biomass. Regarding traditional alkaline pretreatments, there are some advantages, such as high yield in XOS production, low by-product formation, high lignin removal yield and milder operating conditions. Thus, the use of agro-industrial wastes is a promising strategy that encompasses biorefinery concepts, such as the bioconversion of cassava peels to XOS.
Modification of hydrochar requires either toxic chemicals or high temperature during the hydrothermal carbonization process, which are the main shortcomings for industrial upgrading and cleaner production of hydrochar. Herein, a novel green catalyst formed by in-situ deep eutectic solvent (DES, i.e. ChCl-H2O) and inorganic salt (FeCl3) was developed to prepare hydrochars derived from garden waste under low temperature for removing methylene blue (MB). The effects of key operational parameters including different temperatures (160 degrees C-260 degrees C), reacting time (3-9 h) on hydrochars performance were firstly evaluated. It was found that the adsorption capacity of hydrochar on MB reached its highest value of 169.19 mg/g at the optimal temperature of 180 degrees C for 5 h. Subsequent adsorption kinetics study showed that the obtained data fitted better to the pseudo-second-order kinetics. The results indicated that DES and inorganic salts could be used to effectively prepare hydrochar in hydrothermal carbonization process.
In the present work, multi-walled carbon nanotubes (MWCNTs), bamboo charcoal (BC) and activated carbon (AC) have been synthesized via thermal CVD technique by adopting fixed catalyst route and by simple pyrolysis, respectively. A two-terminal device has been fabricated using either MWCNTs, BC or AC as sensing material which was kept between the two terminals. This fabricated device was used for alcohol sensing at room temperature. In order to determine the sensitivity and detection limit, one droplet (similar to 10 mu L) of alcohol (CH3OH, C2H5OH and IPA) as well as IPA/water mixture was drop casted on the sensing material and the variation of resistance with respect to time has been monitored. The plausible explanation of detection has also been proposed taking into account the carriers tunneling between two disordered regions which was being wetted by alcohol molecules. We envision that the fabricated device might be a cost effective solution for the detection of pure as well as dilute isopropyl alcohol. (C) 2018 Published by Elsevier B.V.
Considerable research activities are underway involving microalgae species in order to treat industrialwastewater to address the waste-to-bioenergy economy. Several studies of wastewater treatment usingmicroalgae have been primarily focused on removal of key nutrients such as nitrogen and phosphorus. Although the use ofwastewater would provide nutrients and water for microalgae growth, the whole process is even more complex than the conventional microalgae cultivation on freshwater media. The former one adds several gridlocks to the system. These gridlocks are surplus organic and inorganic nutrients concentration, pH of wastewater, wastewater color, total dissolved solids (TDS), microbial contaminants, the scale of photobioreactor, batch versus continuous system, harvesting of microalgae biomass etc. The present review discusses, analyses, and summarizes key aspects involved in the treatment of wastewaters from distillery, food/snacks product processing, and dairy processing industry using microalgae along with sustainable production of its biomass. This review further evaluates the bottlenecks for individual steps involved in the process such as pretreatment of wastewater for contaminants removal, concentration tolerance/dilutions, harvesting of microalgae biomass, and outdoor scale-up. The review also describes various strategies to optimize algal biomass and lipid productivities for various wastewater and photobioreactor type. Moreover, the review emphasizes the potential of co-cultivation of microorganism such as yeast and bacteria along with microalgae in the treatment of industrial wastewater. (C) 2019 Published by Elsevier B.V.
The main objective of our work is to optimize the 1st step of the dilute sulfuric acid hydrolysis of Moroccan sugar beet pulp. The optimal conditions were not only determined using the response surfaces methodology (RSM). They were defined by applying a multi-objective optimization using a desirability function. The effects of temperature (80-130 degrees C), sulfuric acid concentration (0.75-1.5 \% v/v), and time (40-120 min) on the production of pentoses, hexoses, furfural, and 5-hydroxymethylfurfural (HMF) were determined by experiment according to a central composite design (CCD). These experimental data were exploited to develop four statistical models by RSM, relating the production of each product of pretreated pulp to the operating conditions. All these models produced very satisfactory results, in term of correlation coefficients and student test. These models have been used for a multi-objective optimization to maximize pentoses and hexoses production, and minimize concentrations of furfural and HMF, simultaneously. The optimal conditions were 130 degrees C for temperature, 0.75 (\%, v/v) for sulfuric acid concentration, and 120 min for time. These conditions allowed 85.68 \% of pentoses, 18.6\% of hexoses, 8.53 \% of furfural, and 6.58 \% of HMF.
Lignocellulosic biomass is an excellent raw material for the production of fuels, chemicals and energy. However, its use in a more productive way is conditioned to the use of highly efficient enzymatic cocktails, which can be produced by a plethora of microorganisms. Among them, strains of the genera Aspergillus, Penicillium and Trichoderma are some of the most relevant, corresponding to over 50\% of the studies related to cellulases. In this context, molecular biology tools should be used to favor the enzyme production economics, whereas approaches such as product engineering and supplementation with additives (e.g. surfactants or accessory proteins) should be used to increase the efficiency of the hydrolytic process. In this paper, we shortly address these issues, and discuss some recent advances in the production and use of cellulases from the abovementioned fungal genera.
Introducing multifunctional groups and inorganic material imparts xylan-based hydrogels with excellent properties, such as responsiveness to pH, temperature, light, and external magnetic field. In this work, a composite hydrogel was synthesized by introducing acid treated carbon nanotubes (AT-CNTs) into the maleic anhydride modified xylan grafted with poly(N-isopropylacrylamide) (MAX-g-PNIPAM) hydrogels network. It was found that the addition of AT-CNTs affected the MAX-g-PNIPAM hydrogel structure, the swelling ratio and mechanical properties, and imparted the hydrogel with new properties of electrical conductivity and near infrared region (NIR) photothermal conversion. AT-CNTs could reinforce the mechanical properties of MAX-g-PNIPAM hydrogels, being up to 83 kPa for the compressive strength when the amount was 11 wt \%, which was eight times than that of PNIPAM hydrogel and four times than that of MAX-g-PNIPAM hydrogel. The electroconductibility was enhanced by the increase of AT-CNTs amounts. Meanwhile, the composite hydrogel also exhibited multiple shape memory and NIR photothermal conversion properties, and water temperature was increased from 26 degrees C to 56 degrees C within 8 min under the NIR irradiation. Thus, the AT-CNTs reinforced MAX-g-PNIPAM hydrogel possessed promising multifunctional properties, which offered many potential applications in the fields of biosensors, thermal-arrest technology, and drug-controlled release.
Combination of size reduction and mild alkali pretreatment may be a feasible way to produce bioethanol without rinsing and detoxifying the solid substrate. Based on that, a fermentation configuration named one-pot SSF in which pretreatment and fermentation steps were integrated was developed. Additionally, the effect of laccase on fermentation performance was investigated. Delignification was the major effect of the alkali pretreatment at 121 degrees C for 60 min. The highest glucose and xylose yield, which obtained from the smallest particle at a substrate loading of 2\%, was 6.75 and 2.71 g/L, respectively. Laccase improved the fermentation efficiency by 6.8\% for one-pot SSF and 5.7\% for SSF. Bioethanol from one-pot SSF with laccase supplementation reached 67.56\% of the theoretical maximum, whereas that from SSF with laccase supplementation reached 57.27\%. One-pot SSF might be a promising configuration to produce bioethanol because of 100\% solid recovery, and rinsing water and detoxification elimination. (C) 2014 Elsevier Ltd. All rights reserved.
Banana peel (BP), a biomass waste, was converted into a valuable highly porous functional carbon material (HPFCM) by a general chelate-assisted co-assembly process. The HPFCMs were fabricated by using Al(III)-based metal-organic framework-like as a free-standing template and commercial Pluronic F127 as a microstructure-directing agent. Several critical variables for fabrication including doses of Al(III) and F127, carbonization temperature had been optimized and the adsorption behavior of HPFCMs was examined by using methylene blue as dye model compound. The optimal adsorbent was validated as HPFCMs-5-1-800, and its equilibrium data were well fitted to the Langmuir isotherm model with a monolayer adsorption capacity of 385.12 mg g (1) at ambient temperature. The surface physical properties of HPFCMs-5-1-800 were also exemplarily characterized. The findings revealed that the free-standing template is a potential route for preparation of HPFCM from waste BP. (C) 2013 Elsevier Ltd. All rights reserved.
In this study, cellulose hydrogels were simply fabricated by the chemical dissolution method using LiCl/dimethylacetamide as a new method, and the hydrogel produced was investigated for removing Direct Blue 86 (DB86) dye from the aquatic environment. The produced cellulose hydrogel (CAH) was characterized by FTIR, XRD, SEM, and TGA analyses. The removal efficiency of DB86 dye using CAH was achieved via a batch equilibrium process. The impact of pH, time of contact, CAH dosage, starting concentration of DB86 dye, and absorption temperature were scanned. The optimum pH for absorption of DB86 dye was determined to be 2. The absorption results obtained were scanned by Langmuir (LIM), Temkin (TIM), Freundlich (FIM), and Dubinin-Radushkevich (DRIM) isotherm models (IMs) and chi-square error (X-2) function used to identify the best-fit IMs. The CAH had 53.76 mg/g as a maximum absorption capacity (Q(m)) calculated from the LIM plot. The TIM was the best fitted to the CAH absorption results. Kinetic absorption results were investigated by pseudo-first-order (PFOM), Elovich (EM), pseudo-second-order (PSOM), film diffusion (FDM), and intraparticle diffusion (IPDM) models. A PSOM with a high R-2 (> 0.99) accounted for the majority of the control over the absorption rate. The findings indicate that CAH can potentially remove the DB86 dye from wastewater.
A highly active alkalothermophilic cellulase free xylanase (3446 U/g of dry substrate) has been produced from newly isolated strain of Bacillus stearothermophilus under solid-state fermentation using wheat bran (2.5\%, w/v) pH 7.0 and at 37 degrees C. The xylanase was stable over broad range of pH (6.0-12.5) and temperature (37-85 degrees C) and hence was used in the bioprocessing of fabrics as an alternative to conventional chemical method. The desizing and bioscouring treatments were most efficient at 70 degrees C after 90 and 180 min of incubation respectively using 5 g/l of xylanase dose in the medium of pH 9.5. Enzymatically desized fabrics when subjected to bioscouring resulted in 0.91\%, 0.88\% weight loss for micropoly and 0.83\%, 0.80\% for cotton respectively under agitated (50 +/- 2 rpm) and non-agitated conditions. Consequently Whiteness index for cotton (11.81\%) and micropoly (52.15\%) fabrics was increased. Induction in the release of reducing sugars was also observed for cotton (8.37\%) and micropoly (16.79\%) fabric over conventional method. Enzymatically processed fabric samples possessed 1.12\% and 1.95\% more tensile strength than reference. Tearness value also increased for bio-treated cotton (1.57\%) and micropoly (2.37\%) fabric samples as compared to control. (C) 2008 Elsevier Inc. All rights reserved.
The effects of pH on residual solids (RS), total dissolved solids (TDS), carbohydrates, and lignin in eucalyptus during hydrothermal pretreatment were studied. The balance between RS and TDS was obtained at pH 4.0 in hydrothermal pretreatment with pre-adjustment pH. The yield of hemicellulose increased, and oligosaccharides dominated. Hemicellulose had the highest dissolution rate, and cellulose and lignin had the lowest dissolution rate at pH 4.0. The crystallinity index (Cr!) and structural transformation of lignin was analyzed by X-ray diffraction (XRD) and nuclear magnetic resonance spectroscopy (NMR) with or without pretreatment. The Crl at pH 4.0 was 64.2\% higher than that with the traditional hydrothermal pretreatment (62.1\%). The beta-0-4 bonds, OMe, and phenylcoumarane of lignin were protected. The highest hemicellulose extraction and minimal physicochemical structural changes were obtained at pH 4.0.
Carboxylated corn stalk was prepared successfully by introducing amide and carboxyl groups into the cellulose structure, and were utilized as an efficient adsorbent to remove cadmium ions from an aqueous solution in batch adsorption process. The maximum adsorption capacity could be achieved 47.17 mg/g at the initial pH 5.8 of aqueous solution, significantly higher than most reported adsorbents. Meanwhile, changing of temperature could not greatly affect during the adsorption process. In addition, this adsorbent had a high selectivity of the cadmium ions in co-existing ions solution, but lead ions exerted obviously a compete effect upon the adsorption of cadmium ions. The adsorption isotherm could be correctly simulated by Langmuir and Freundlich isotherms. Whereas, the adsorption kinetics followed the pseudo-second-order kinetic model. Also, Thermodynamic parameters confirmed that adsorption was exothermic and chemisorption in nature. Based on the results of X-ray photoelectron spectra, the adsorption mechanism was ascribed mainly to the coordination complex between cadmium ions and the oxygen of carbonyl groups, relative to the effect of the nitrogen of amine groups. Regeneration of the adsorbent was performed with 0.1 g/L ethylenediaminetetraacetic acid to provide five cyclical regeneration. (C) 2018 Elsevier Ltd. All rights reserved.
Alkali-silica reaction (ASR) in concrete structures is very common problem around the globe. In this study, the potential of rice husk ash (RHA) in mitigating the ASR expansion was investigated. For this purpose, aggregates from reactive source were selected. RHA was acquired from local industry. Mortar bar specimens were prepared with various RHA proportions (10\%, 20\%, 30\% and 40\% by cement weight) to evaluate the ASR expansion in accordance with ASTM C1260. The pozzolanic reactivity of RHA was also evaluated using strength activity index and thermal analysis. Results showed satisfactory level of pozzolanic reactivity when cement was partially replaced with RHA. Mortar bars expansion results showed 23\% and 50\% decrease in expansion for specimen incorporating 10\% and 40\% of RHA, respectively. Scanning electron microscopy (SEM) also showed cracking due to ASR in control specimehs; however, no cracks were observed in mortar bar specimens incorporating RHA. Moreover, energy disperse X-ray spectroscopy (EDS) analysis of mortar bars incorporating RHA showed low calcium to silica ratio with higher amount of alumina which may resulted into alkali reduction due to alkali absorption and dilution process leading to reduce the ASR expansion. Therefore, the incorporation of RHA as a pozzolanic material can be helpful in binding alkalies and mitigating the ASR expansion. (C) 2016 Elsevier Ltd. All rights reserved.
Hematite/graphene oxide (FGO) nanocomposites were used as a supporting surface for the fungus Aspergillus terreus AUMC-050 to form AFGO biofilm. Different techniques were used for characterization of nanocomposites and biofilm such as IR, Fourier transform infrared, Scanning electron microscopy, Transmittance Electron Microscopic, Brunauer-Emmett-Teller surface area, and Raman Spectroscopy. The effect of initial dye concentration (0-300mg/L), contact time (0-80min), pH values (2.0-8.0), and temperature (10-50 degrees C) was studied. The maximum adsorption capacity of dye using AFGO biofilm was 160mg dye/g at pH 2.0, and the contact time was 50min. The best fitted equilibrium and kinetic model were found to be Langmuir and pseudo-first order, respectively. Various thermodynamic parameters were evaluated to determine the nature of biosorption process. The negative value of G and H degrees indicated spontaneity and exothermic behavior of the adsorption process. Using of microbial biofilm supported on nanocomposite material is a new approach for adsorption of dyes from water body.
The remediation of Pb-contaminated soil has become an international concern in recent decades due to mines exploitation and fertilizer abuse. Batch chemical soil washing experiments were conducted to optimize Pb removal efficiency from contaminated soil by two biodegradable chelants, citric acid (CA) and {[
The coconut industry has great economic importance for the Asia-Pacific region and Brazil. For this reason, researchers have given special attention to coconut shells and fibers as fuel sources. However, other residues as coconut inflorescence wastes (CIW) have been neglected. In this work, CIW were pyrolyzed. Effects of pyrolysis temperature (290-710 degrees C) and heating rate (2-58 degrees C center dot min(-1)) were evaluated. A full factorial design (FFD) was developed to identify interaction effects. Product (biochar, gas and bio-oil) yield and phenol concentration in the bio-oil (C-Phenol) were the responses investigated. Response surface methodology and central composite design (CCD) were used to obtain optimum conditions. Biomass and bio-oil were further characterized by thermogravimetric (TG) and GC-MS analyses. TG results indicated the FFD levels. Temperature and heating rate showed significant effects on the responses. A linear model was suitable for gas yield, while quadratic models were fitted to other responses. A trade-off analysis between bio-oil yield and C-Phenol detected optimum values of 42.9\% and 47.1 mg g(-1) at 530 degrees C and 4.0 degrees C min(-1). Finally, phenolic compounds accounted for 77.8\% of total peak area of the bio-oil based on GC-MS results. Therefore, bio-oil produced by pyrolysis of CIW showed to be a promising source of phenols for industrial use. {[
The pretreatment of a high lignin substrate, coconut coir dust, was studied by chemical techniques (NaOH solution, ionic liquid, and NaOH followed by ionic liquid) and by a physical method (subcritical water, SCW). Following substrate pretreatment and a washing step, structural analyses were performed by scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. It was found that all substrates pretreated by chemical methods had more amorphous structures than the untreated substrate. The XRD patterns of the chemically treated substrates shifted toward higher angles by 0.50 degrees to 1.00 degrees. However, the XRD peak symmetry of the SCW-treated substrate did not shift, but its crystallinity index decreased. The results revealed that lignocellulose treated with NaOH followed by ionic liquid at 120 degrees C for 30 min showed the greatest extent of structural transformation.
Xylitol production from corncob hemicellulose is a popular process in China. Microbial conversion of xylose to xylitol, as a biological process with many advantages, has drawn increasing attention. As a by-product from the manufacturing of xylitol, corncob cellulosic residues are produced in very large amounts and represent an environmental problem. As a result, considering the large amount of xylitol production in China, the conversion of corncob cellulosic residues has become a widespread issue having to be tackled. After the hemicellulose in corncob has been hydrolyzed for xylitol production, the corncob cellulosic residue is porous and can easily be hydrolyzed by cellulases into glucose and further converted to ethanol, another high-added-value chemical. Based on the latest technology advancements in xylitol, cellulase, and ethanol production, the integrated production of ethanol from corncob cellulosic residues appears as a promising way to improve the profit of the whole xylitol production process.
This investigation explores the chemical modification of cellulose by using a quasi solvent-free procedure, in which the biopolymer was added to molten maleic anhydride, producing a mixture of maleated and fumarated celluloses. Using this pathway mainly surface modifications are observed and more than 2.82 +/- 0.05 mmol of modifier per gram of synthesized polymer were obtained. These chemically modified materials were characterized by elemental analysis, solid-state C-13 NMR CP/MAS, FTIR, XRD, TG and SEM. The chemically modified polysaccharides are able to adsorb cations. The data were adjusted to a modified Langmuir equation to give 1.75 +/- 0.09 and 2.40 +/- 0.12 mmol/g of Co2+ and Ni2+, respectively. The net thermal effects obtained from calorimetric titration measurements were also adjusted to a modified Langmuir equation and the enthalpy of the interaction was calculated to give the endothermic values of 0.29 +/- 0.02 and 0.87 +/- 0.02 kJ/mol for Co2+ and Ni2+, respectively. The thermodynamic data for these systems are favorable for cation adsorption from aqueous solutions at the solid/liquid interface, suggesting the use of this anchored biopolymer for cation removal from the environment. (C) 2009 Elsevier B.V. All rights reserved.
Understanding optimal process conditions is an essential step in providing high-quality fuel for energy production, efficient energy generation, and plant development. Thus, the effect of process conditions such as the temperature, time, nitrogen-to-solid ratio (NSR), and liquid-to-solid ratio (LSR) on pretreated waste pine sawdust (PSD) via torrefaction and solvolysis is presented. The desirability function approach and genetic algorithm (GA) were used to optimize the processes. The response surface methodology (RSM) based on Box-Behnken design (BBD) was used to determine the effect of the process conditions mentioned above on the higher heating value (HHV), mass yield (MY), and energy enhancement factor (EEF) of biochar/hydrochar obtained from waste PSD. Seventeen experiments were designed each for torrefaction and solvolysis processes. The benchmarked process conditions were as follows: temperature, 200-300 degrees C; time, 30-120 min; NSR/LSR, 4-5. In this study, the operating temperature was the most influential variable that affected the pretreated fuel's properties, with the NSR and LSR having the least effect. The oxygen-to-carbon content ratio and the HHV of the pretreated fuel sample were compared between the two pretreatment methods investigated. Solvolysis pretreatment showed a higher reduction in the oxygen-to-carbon content ratio of 47\%, while 44\% reduction was accounted for the torrefaction process. A higher mass loss and energy content were also obtained from solvolysis than the torrefaction process. From the optimization process results, the accuracy of the optimal process conditions was higher for GA (299 degrees C, 30.07 min, and 4.12 NSR for torrefaction and 295.10 degrees C, 50.85 min, and 4.55 LSR for solvolysis) than that of the desirability function based on RSM. The models developed were reliable for evaluating the operating process conditions of the methods studied.
The present investigation presents a novel hybrid solar-biomass system for electric power generation in remote areas. The proposed system integrates a Supercritical Brayton Cycle (SBC) to an Organic Rankine Cycle (ORC) as a bottoming cycle, driven by a Concentrated Solar Tower (CST) system and biomass furnace (coconut shell). The thermal energy generation potential of the biomass was determined from the fiber content, lignin, density, calorific value, and ash content, and the level of pollutant emissions at different combustion rates. Energy and exergy analyses were carried out considering three scenarios: hybrid solar-biomass SBC-ORC, SBC-ORC/solar, and SBC-ORC/biomass. The results revealed that coconut shells feature a low content of inorganic matter with a calorific value of 25.29 MJ/kg, and the best combustion efficiency (CO2/CO) was given at a speed of 0.0895 degrees C.min(-1) (43.16\%). The hybrid solar-biomass SBC-ORC system showed an exergetic efficiency of 26.60\%, an increase of 17.28\% with respect to the SBC-ORC/solar system in its base condition. The turbine inlet temperature was the variable with the greatest influence on the exergetic efficiency of the SBC-ORC/solar system, which reached a maximum of 23.8\% at 700 degrees C. In conclusion, the integration of coconut shell biomass as an alternative and supplementary thermal source is a promising solution for the intermittence of solar-driven systems. This study demonstrated that the novel hybrid system ensures stability, good combustion efficiency, and enhanced performance compare to the standalone solar operation. (C) 2021 Elsevier Ltd. All rights reserved.
Rosin esters are widely applied as masticatory substances and beverage stabilizers, while classical acid-catalysed processes will lead to metal residue or environmental issues. Super/subcritical CO2-enriched high temperature liquid water (HTLW) as a green acid catalyst in the esterification reaction of rosin with glycerol was investigated. The pH of CO2-H2O binary system, as calculated based on gas-liquid equilibrium, charge balance and chemical equilibrium equations, ranged from 3.49 to 3.70 depending on the reaction conditions, indicating effective acid catalysis. Response surface methodology experiments showed the optimum conditions were 3.5 h, 3.9 MPa CO2 pressure, a rosin-to-glycerol molar ratio of 1.32 and 269 degrees C, and an enhanced esterification yield of 94.74\% was achieved, which was superior to that obtained using a ZnO catalyst. It was found that the esterification kinetics was a pseudo first-order reaction, and the enthalpy and entropy of activation were calculated using the Arrhenius-Polanyi equation. The presence of super/subcritical CO2-enriched HTLW catalyst can decrease the activation energy and significantly accelerate the reaction rate.
Phenolic compounds may exist in the gum generated from rapeseed oil refining as rapeseed is rich in phenolics. Therefore, this work identified the main phenolic compounds, followed by tracking their flow according to typical lecithin production procedures. Antioxidant activities of the extracts were also investigated to get a clue of the potential oxidative stability of the final products. Column chromatography, UV spectra, H-1 NMR, and HPLC were used to separate and identify the phenolic compounds. Sinapic acid was found to be the dominant phenolic while relatively low contents of sinapine and canolol were also identified. Nonpolar solvent aid extraction was better for extracting more sinapine and sinapic acid while direct ethanol extraction gave more canolol. Almost half of the phenolics in dried gum were removed by acetone during deoiling process, leaving only a small amount in deoiled lecithin. Extracts from deoiled lecithin showed the weakest antioxidant activity while the ethanol solubles showed the strongest. This work demonstrated the occurrences of bioactive phenolic compounds in rapeseed originated gum, which may be an advantage of rapeseed lecithin compared with other types of lecithin. This work could also be a reference for rapeseed lecithin production with different contents of bioactive compounds in industry. (C) 2016 Elsevier Ltd. All rights reserved.
Background: The filamentous fungus Penicillium oxalicum is a potential alternative to Trichoderma reesei for industrial production of a complete cellulolytic enzyme system for a bio-refinery. Comparative omics approaches can support rational genetic engineering and/or breeding of filamentous fungi with improved cellulase production capacity. In this study, comparative genomic, transcriptomic and secretomic profiling of P. oxalicum HP7-1 and its cellulase and xylanase hyper-producing mutant EU2106 were employed to screen for novel regulators of cellulase and xylanase gene expression. Results: The 30.62 Mb P. oxalicum HP7-1 genome was sequenced, and 9834 protein-coding genes were annotated. Re-sequencing of the mutant EU2106 genome identified 274 single nucleotide variations and 12 insertion/deletions. Comparative genomic, transcriptomic and secretomic profiling of HP7-1 and EU2106 revealed four candidate regulators of cellulase and xylanase gene expression. Deletion of these candidate genes and measurement of the enzymatic activity of the resultant mutants confirmed the identity of three regulatory genes. POX02484 and POX08522, encoding a putative Zn(II)(2)Cys(6) DNA-binding domain and forkhead protein, respectively, were found to be novel, while PoxClrB is an ortholog of ClrB, a key transcriptional regulator of cellulolytic enzyme gene expression in filamentous fungi. Delta POX02484 and Delta POX08522 mutants exhibited significantly reduced beta-glucosidase activity, increased carboxymethylcellulose cellulase and xylanase activities, and altered transcription level of cellulase and xylanase genes compared with the parent strain Delta PoxKu70, with Avicel as the sole carbon source. Conclusions: Two novel genes, POX02484 and POX08522, were found and characterized to regulate the expression of cellulase and xylanase genes in P. oxalicum. These findings are important for engineering filamentous fungi to improve cellulase and xylanase production.
The present study was conducted to develop a simple and versatile method to prepare carboxylated bamboo fibers which can be applied as potential bio-adsorbent for metal ions removal due to the high content of carboxyl groups. The chemical modification of bamboo fibers with citric acid (CA) was carried out by friendly semi-dry oven method. The resulting products with carboxyl group content between 1.99 and 4.13 mmol/g were accessible by changing ultrasonic pretreatment time, reaction temperature, reaction time and the amounts of catalyst and citric acid in order to minimize cross-linking reaction and thereby maximize carboxyl groups content. The characterization of the resulting products confirmed that carboxyl groups were successfully grafted onto surface of bamboo fibers. Moreover, the carboxylated bamboo fibers could be applied as bio-adsorbent for the removal of lead(II) ions from aqueous solution. Results showed that the adsorption capacity of Pd2+ could reach 127.1 mg/g for carboxylated bamboo fibers with 4.13 mmol/g carboxyl group content prepared under the ultrasonic pretreatment for 20 min at the CA/bamboo fibers weight ratio of 4.0 in the catalyst amount of 30 wt\% at 120 A degrees C for 90 min and the carboxylated bamboo fibers exhibited highly efficient regeneration with no significant loss of adsorption capacity of lead ion after five repeated adsorption/desorption cycles.
A considerable amount of food waste generated globally could be upcycled to synthesise platform chemicals to enhance environmental sustainability and realise a circular economy. This study investigates the catalytic production of the vital platform molecule levulinic acid (LA) from bread waste, a typical stream of starch-rich food waste generated worldwide. Gamma-valerolactone (GVL), isopropanol (IPA), and propylene carbonate (PC) were evaluated as bio-derived and CO2-derived green co-solvents for LA synthesis. In-vessel pressure generated in PC/H2O (1 : 1) solvent was conducive to rapid LA production from bread waste compared to GVL/H2O and IPA/H2O. In PC/H2O, 72 mol\% total soluble product yield was observed quickly within 1 min in moderate reaction conditions (130 degrees C, 0.5 M H2SO4), whereas similar to 15-20 mol\% of LA could be obtained when the reaction was prolonged for 10-20 min at 130 degrees C. The yield of LA could be significantly enhanced in GVL/H2O through phase separation using NaCl (30 wt\%((aq))). LA yield increased up to a maximum of similar to 2.5 times in the biphasic system (28 mol\%, 150 degrees C, 15 min) (representing a theoretical yield of 66\%) in GVL/H2O (1 : 1) compared to the monophasic system (similar to 11 mol\%) under the same reaction conditions. The partition coefficient for LA achieved was 4.2 in the GVL/H2O (1 : 1) biphasic medium, indicating that the system was efficient for simultaneous production and extraction of LA. Biphasic GVL/H2O facilitated selective LA production, which could be optimised by tuning the reaction conditions. These new insights can foster the development of high-performance LA production and sustainable biorefinery.
Biochar, a carbon-rich and por ous material derived from waste biomass resources, has demonstrated tremendous potential in wastewater treatment. Torrefaction technology offers a favorable low-temperature biochar production method, and torrefied biochar can be used not only as a solid biofuel but also as a pollutant adsorbent. This review compares torrefaction technology with other thermochemical processes and discusses recent advancements in torrefaction techniques. Additionally, the applications of torrefied biochar in wastewater treatment (dyes, oil spills, heavy metals, and emerging pollutants) are comprehensively explored. Many studies have shown that high productivity, high survival of oxygen-containing functional groups, low temperature, and low energy consumption of dried biochar production make it attractive as an adsorbent for wastewater treatment. Moreover, used biochar's treatment, reuse, and safe disposal are introduced, providing valuable insights and contributions to developing sustainable environmental remediation strategies by biochar.
The present study addresses valorisation of abundantly available, low-cost pine needle (PN) waste into cellulolytic enzymes and high calorific value (CV) fuel pellets (FP). Initial studies in flasks involving hot water steam pre-treatment (HWSP) using Aspergillus niger MTCC 9652 for 5 days resulted in an increase in Cellulase, Endoglucanase and Xylanase activities compared to the untreated pine needles (UPN). Fermentation experiments were scaled-up in a 6-L Solid State fermentation (SSF) packed bed reactor (PBR) at different bed heights (BH) using UPN. The maximum cellulase and xylanase yields were achieved as 9.97 +/- 0.27 FPU g-ds(-1) and 8276 +/- 254 IU g-ds(-1), respectively, at 72 h using UPN in the PBR. The fermented residue showed 53.5\% consumption of holocellulose, a decrease in crystallinity index to 29.5\% from 46\%, with an increase in total lignin content of 45.9\%. The fermented residue was processed for pellet production, resulting in a higher CV (19.13 +/- 0.69 MJ kg(-1)) than the pellet made from unfermented PN (17.63 +/- 0.66 MJ kg(-1)), along with enhanced compressive strength. Sulphur content (0.14\%) was below the permissible limit of SOx emission for fuels with ash content less than 5\%. Therefore, the present study represents a novel and sustainable biorefinery approach for PN valorisation. (C) 2022 Elsevier Ltd. All rights reserved.
Complete aqueous dissolution of starch requires the use of temperatures exceeding 100 degrees C. During and after cooling of the resultant aqueous solutions, starch polymers precipitate by aggregation and crystallization. Low-temperature gelatinization and dissolution of maize starch (MS) is induced, and the stability of the resultant solutions is enhanced when they contain the hydrotrope sodium salicylate (NaSal). Differential scanning calorimetry and optical microscopy evidence showed that MS gelatinization shifts to lower temperatures and that the associated enthalpy decreases with increasing NaSal concentrations. The enhanced gelatinization and dissolution are probably brought about by the association of NaSal with the more hydrophobic MS structural moieties. The minimum NaSal content of aqueous mixtures allowing full gelatinization of MS at room temperature, that is, about 11 wt \%, was found to be independent of MS content (in the range 10-66.7 wt \% MS).
This study optimized the co-valorization of corn cob wastes (CCW) and dairy wastewater for simultaneous saccharification and lactic acid (LA) production (sDWW-SSF). Subsequently, the kinetics of Lactobacillus plantarum growth and LA production was assessed using the optimized conditions under microaerophilic (sDWWSSFmicroaerophilic) and anaerobic (sDWW-SSFanaerobic) conditions, and thereafter compared to De Man, Rogosa and Sharpe (MRS) medium modified with pretreated CCW (mMRS-SSFmicroaerophilic). Optimized sDWW-SSF conditions produced maximum LA concentration and conversion of 11.15 +/- 0.42 g/L and 18.90 +/- 0.75\%, respectively. Kinetic studies revealed that although the mMRS-SSFmicroaerophilic system obtained a higher maximum specific growth rate (mu max) and maximum potential LA concentration (Pm) compared to the wastewater-based bioprocesses, the data obtained for the latter were comparable when taking the resources and costs into consideration. These findings represent the potential to eliminate the use of valuable resources in lignocellulosic bioprocesses and provide insights on innovation towards driving a sustainable economy in line with the foodenergy-water nexus.
Lignocellulosic biomass processing employing ionic liquids is of recent research interest for the biorefinery industry. The data on biomass dissolution kinetics in ionic liquids is important for designing scale-up pre-treatment reactor design. In this study, the reaction mechanism and kinetics of oak wood dissolution in aqueous choline chloride was investigated. In an extended effort, a correlation of dimensionless numbers was developed for the estimation the mass transfer coefficient. The analyses suggested that oak wood dissolution in choline chloride occurred in two stages. The diffusion of ionic liquid through the product layer was the dominating rate-controlling step in the first stage of dissolution followed by the surface chemical reaction in the second stage. The diffusivity of choline chloride into the oak wood matrix was ranging between 2.96E-14 and 2.84E-13 m(2)/s. The activation energy of the diffusion controlled stage and surface chemical reaction controlled stage was approximately 24.2 and 40.3 kJ mol(-1), respectively. The proposed mathematical correlation for mass transfer coefficient fitted well with the experimental mass transfer coefficient values.
Production of renewable fuel like bioethanol from plant biomass and agro wastes will be the future energy source to combat the depletion of fossil fuels. The first detailed profile of the non-cellulosic cell wall polysaccharides of native, ultrasonication assisted alkaline (NaOH) pre-treated and enzyme hydrolysed Pennesitum grass varieties viz. hybrid Napier grass and denanath grass, were identified using glycome profiling. The best pre-treatment conditions resulted in 89.3\% and 86.7\% delignification of denanath grass (DG) and hybrid Napier grass (HNG) respectively. In the same conditions, 227.2 mg/g and 242.8 mg/g of total reducing sugar was achieved for DG and HNG respectively. Comparative assessment of a new enzyme i. e. Palkonal MBW with the conventional combination of Celluclast 1.5 L+ xylanase was undertaken. The amounts of glucose and xylose released with Palkonal MBW saccharified DG and HNG were 662.0 mg/g and 431.2 mg/g, which were significantly higher as compared to the conventional enzyme cocktail. The glycome profiling results showed that pectic arabinoxylan and arabinogalactan backbones were significantly less in DG samples and they do play a major role in enhancing enzymatic hydrolysis. These reports can provide a good insight in designing potential perennial feedstocks for bioethanol production in bio refinery concepts. Furthermore, the underutilised DG variety may also be exploited owing to its promising cell wall characteristics that can produce higher bioethanol yields.
The depletion of fossil fuel reserves has led to increasing interest in liquid bio-fuel from renewable biomass. Biomass is a complex organic material consisting of different degrees of cellulose, hemicellulose, lignin, extractives and minerals. Some of the mineral elements tend to retard conversions, yield and selectivity during pyrolysis processing. This study is focused on the extraction of mineral retardants from Napier grass using deionized water, dilute sodium hydroxide and sulfuric acid and subsequent pyrolysis in a fixed bed reactor. The raw biomass was characterized before and after each pretreatment following standard procedure. Pyrolysis study was conducted in a fixed bed reactor at 600 A degrees C, 30 A degrees C/min and 30 mL/min N-2 flow. Pyrolysis oil (bio-oil) collected was analyzed using standard analytic techniques. The bio-oil yield and characteristics from each pretreated sample were compared with oil from the non-pretreated sample. Bio-oil yield from the raw sample was 32.06 wt\% compared to 38.71, 33.28 and 29.27 wt\% oil yield recorded from the sample pretreated with sulfuric acid, deionized water and sodium hydroxide respectively. GC-MS analysis of the oil samples revealed that the oil from all the pretreated biomass had more value added chemicals and less ketones and aldehydes. Pretreatment with neutral solvent generated valuable leachate, showed significant impact on the ash extraction, pyrolysis oil yield, and its composition and therefore can be regarded as more appropriate for thermochemical conversion of Napier grass.
Two types of lignins occurred in different lignin-carbohydrate fractions, a lignin enriched in syringyl units, less condensed, preferentially associated with xylans, and a lignin with more guaiacyl units, more condensed, associated with glucans. Lignin-carbohydrate complexes (LCC) were isolated from the fibers of sisal (Agave sisalana) and abaca (Musa textilis) according to a plant biomass fractionation procedure recently developed and which was termed as ``universally{''