In this study, mixed softwoods were pretreated with an ionic liquid, 1-butyl-3-methylimidazolium chloride ({[
Over the years, extensive urbanization and industrialization have led to xenobiotics contamination of the environment and also posed a severe threat to human health. Although there are multiple physical and chemical techniques for xenobiotic pollutants management, bioremediation seems to be a promising technology from the environmental perspective. It is an eco-friendly and low-cost method involving the application of microbes, plants, or their enzymes to degrade xenobiotics into less toxic or non-toxic forms. Moreover, bioremediation involving enzymes has gained an advantage over microorganisms or phytoremediation due to better activity for pollutant degradation with less waste generation. However, the significant disadvantages associated with the application of enzymes are low stability (storage, pH, and temperature) as well as the low possibility of reuse as it is hard to separate from reaction media. The immobilization of enzymes without affecting their activity provides a possible solution to the problems and allows reusability by easing the process of separation with improved stability to various environmental factors. The present communication provides an overview of the importance of enzyme immobilization in bioremediation, carrier selection, and immobilization methods, as well as the pros and cons of immobilization and its prospects.
As an abundant biopolymer, lignin gains interest owing to its renewable nature and polyphenolic structure. It possesses many biological activities such as antioxidant activity, antimicrobial activity, and biocompatibility. Studies are being carried out to relate the biological activities to the polyphenolic structures. These traits present lignin as a natural compound being used in biomedical field. Lignin nanoparticles (LNPs) are being investigated for safe use in drug and gene delivery, and lignin-based hydrogels are being explored as wound dressing materials, in tissue engineering and 3D printing. In addition, lignin and its derivatives have shown the potential to treat diabetic disease. This review summarizes latest research results on the biological activities of lignin and highlights potential applications exampled by selective studies. It helps to transform lignin from a waste material into valuable materials and products.
An effective utilization technique is required to recycle fine aggregate in concrete waste because the presence of residual waste cement reduces the quality of the recycled concrete. In this study, recycled aggregate powder (RAP) was prepared by milling Okinawan concrete waste and developing a ceramic compact with high flexural strength using the spark plasma sintering (SPS) method. The RAP raw material consisted mainly of calcite and quartz. The densification gradient of the sintered compact was uniform during sintering at 1123-1273 K At 1273 K sintering temperature, Vickers hardness (HV) obtained a maximum of 393 along with 78.9 MPa maximum flexural strength, which exceeded the porcelain stoneware tile ISO 13006 standards. Scanning electron microscopy with energy dispersive X-ray (SEM-EDX) element analysis suggested that the inner structure constituted unlimited silica-rich sand particles and melted calcium-rich particles containing waste cement and fine aggregate with limestone. Therefore, it can be concluded that SPS progressed by the liquid-phase sintering phenomenon between sand particles and calcium-rich particles, which contributed to flexural strength and modulus improvement.
Pyrolysis is a sustainable pathway to transform renewable biomasses into both biofuels and advanced carbonaceous materials (i.e. pyrochar) which can be used as adsorbent of furan compounds. In particular, the aim of this study was to: i) evaluate the effect of vibro-ball milling on physical characteristics of pyrochar and its consequent performance on solely detoxification of a synthetic medium, containing furans and soluble sugars; ii) study the simultaneous detoxification and bioethanol fermentation, by adding activated pyrochar into fermentation medium. Results demonstrated that, compared to untreated pyrochar, the use of milled pyrochar increased by 52\% furfural removal from the synthetic medium. Furfural removal rate was also increased (adsorption kinetic constant increased from 0.015 min(-1) up to 0.215 min(-1)), at a pyrochar loading of 40 g L-1. Although, the simultaneous addition of pyrochar into the fermentation medium did not improve the bioethanol yield of the synthetic medium, it has significantly increased the bioethanol production rate. (C) 2016 Elsevier Ltd. All rights reserved.
Cationization of agricultural by-products using metal salts is widely used to activate their phosphorous capture ability. This study developed three kinds of new metal loaded soybean milk by-product `okara' for phosphorus biosorption. A comparative study among these biosorbents was carried out with respect to their performances in terms of affinity, stability and reusability. Zirconium loaded okara (ZLO) was found to have the highest affinity towards PO43 anions (47.88 mg/g), followed by iron/zirconium loaded okara - IZLO (40.96 mg/g) and iron loaded okara - ILO (16.39 mg/g). ZLO was successfully desorbed with 0.2 M NaOH and activated with 0.1 HCl prior to the next cycle. After five consecutive cycles, the efficiency of both adsorption and desorption of ZLO remained about 85\% whilst no Zr(IV) leakage was observed. Conversely, IZLO and ILO suffered from vital short comings such as high metal release and/or sharp reduction in PO43 sequestering capability after multi operation cycles. (C) 2014 Elsevier Ltd. All rights reserved.
Modeling of lignocellulosic biomass pyrolysis processes can be used to determine their key operating and design parameters. This requires significant amount of information about pyrolysis kinetic parameters, in particular the activation energy. Thermogravimetric analysis (TGA) is the most commonly used tool to obtain experimental kinetic data, and isoconversional kinetic analysis is the most effective way for processing TGA data to calculate effective activation energies for lignocellulosic biomass pyrolysis. This paper reviews the overall procedure of processing TGA data for isoconversional kinetic analysis of lignocellulosic biomass pyrolysis by using the Friedman isoconversional method. This includes the removal of ``error{''
Microalgae are photosynthetic microbes that can synthesize compounds of therapeutic potential with wide ap-plications in the food, bioprocessing and pharmaceutical sector. Recent research advances have therefore, focused on finding suitable economic substrates for the sustainable cultivation of microalgae. Among such substrates, food derived waste specifically from the starch, meat, dairy, brewery, oil and fruit and vegetable processing industries has gained popularity but poses numerous challenges. Pretreatment, dilution of waste water supernatants, mixing of different food waste streams, utilizing two-stage cultivation and other biorefinery approaches have been intensively explored for multifold improvement in microalgal biomass recovery from food waste. This review discusses the advances and challenges associated with cultivation of microalgae on food waste. The review suggests that there is a need to standardize different waste substrates in terms of general composition, genetically engineered microalgal strains, tackling process scalability issues, controlling waste-water toxicity and establishing a waste transportation chain.
This work aims to evaluate the thermal decomposition kinetics of coconut fiber in a thermogravimetric analyzer using four heating rates (5 - 20 degrees C/min) in nitrogen atmosphere. Three decomposition stages were identified (dehydration, pyrolysis, and carbonization) and the pyrolysis kinetic was performed considering two reaction models (single- and multi-step). In the first model, the apparent activation energy (94.5-210.8 kJ/mol) was determined using five isoconversional methods, and the reaction model representative was the three-dimensional diffusion model, f(alpha) = (3/2) (1-alpha)(2/3) {[
The world's growing population and industrial activities have led to increased energy demand and the depletion of fossil fuels, causing environmental pollution and global warming. A paradigm shift from fossil fuel resources to sustainable energy sources is therefore inevitable. The production of biofuel, such as biochar, from biomass has been receiving increased research attention due to its benefits, which address several environmental issues while advancing the circular economy and sustainable development. This manuscript presents a comprehensive overview of the conversion of coconut biomass residue into biochar, focusing on production methods, physicochemical properties, and versatile applications. Various techniques that have been used for coconut biochar production, including pyrolysis, gasification, torrefaction, and hydrothermal carbonization, are examined in detail, considering their potential for sustainable resource utilization. The interplay between production parameters and resultant biochar characteristics is underscored, elucidating the influence of feedstock composition, pyrolysis conditions, and activation procedures. The findings revealed that the produced biochar has been employed in wastewater treatment, soil amendment, and carbon sequestration, among others. This vast application is a result of the biochar's distinct physicochemical properties, including high porosity, substantial surface area, the presence of several surface functional groups, and thermal stability. Notwithstanding, biochar production from coconut residues faces several challenges. These challenges were addressed in this review, and relevant recommendations were proposed.
This study describes the synthesis of a new bioadsorbent with zwitterionic characteristics and its successful application for removal of a cationic dye (crystal violet, CV) and an anionic dye (orange II, OII) from single component aqueous systems. The new bi-functionalized cellulose derivative (MC3) was produced by chemical modification of cellulose with succinic anhydride and choline chloride to introduce carboxylic and quaternary ammonium functional groups on the cellulose surface. MC3 was characterized by several wet chemical and spectroscopic methods. The effects of solution pH, contact time, and initial solute concentration on removal of CV and OII by MC3 were investigated. Studies of the desorption and re-adsorption of the dyes were also carried out. The isotherms for adsorption of CV and OII on MC3 were satisfactorily fitted using the Konda and Langmuir models. MC3 showed experimental maximum adsorption capacities of 2403 mg g-1 for CV and 201 mg g-1 for OII. The desorption and re-adsorption results showed that MC3 could be reused in successive adsorption cycles, which is essential for minimizing process costs and waste generation. The findings showed that MC3 is a versatile biosorbent capable of efficiently removing both cationic and anionic dyes.
Rapid depletion of petroleum fuels with high fluctuating market prices have enforced mankind to switch for an alternate fuel. The present investigation reports a comparison on the effect of Induction heating and LPG heating for acid hydrolysis of cocoa pod biomass (CPB) to carryout ABE fermentation for the production of biobutanol. The effect of Sulphuric acid (H2SO4), CPB load and residence time on release of total sugar was studied and optimized using Central Composite Design (CCD). The optimum condition for the pretreatment by induction heating was found to be 3.05 (\%v/v) of H2SO4, 11.51 (\%w/v) of CPB and 41.43 min of residence time with 36.26 g/L of total sugar. Similarly for LPG heating an optimum of 25.66 g/L of total sugar released with pretreatment condition 4.03 (\%v/v) of H2SO4, 6.53 (\%w/v) of CPB and 64 min of residence time was observed. The treatment of high biomass load with low concentration of acid in lesser time makes induction heating energy efficient and cost effective. The CPB hydrolysate produced through Induction and LPG heating was allowed to undergo anaerobic fermentation, using Clostridium acetobutilicum MTCC11274. The ABE yield produced using induction assisted CPB hydrolysate was 5.04 +/- 0.32 g/L of acetone, 11.73 +/- 0.84 g/L butanol and 1.43 +/- 0.04 ethanol in 312 h with total ABE of 18.25 +/- 1.17 g/L. The resulted ABE fermentation yield was higher than the LPG assisted CPB hydrolysate with 1.69 +/- 0.17 g/L acetone, 3.36 +/- 0.27 g/L butanol and 0.22 +/- 0.08 g/L ethanol with total ABE of 5.27 +/- 0.51 g/L. The less energy consumption, higher conversion of carbohydrate and great fermentability of hydrolysate makes induction assisted acid pretreatment method significant in biofuel industry.
This work tailored a promising two-step pretreatment, i.e., liquid hot water extraction followed by mild acidic deep eutectic solvents pretreatment for clean lignocellulose fractionation while enhancing cellulose reactivity for its subsequent utilization. The abilities of three acidic deep eutectic solvents (formic acid-, acetic acid- and lactic acid-choline chloride) to selectively extract poplar wood lignin and enhance cellulose reactivity were comparatively assessed. Results showed that rather high lignin selectivity of 6.3-7.9 was obtained while the available area and porosity of the resulting cellulose were significantly increased. The resulting cellulose pulps exhibited comparable chemical reactivity to commercial bleached Kraft pulp when cellulose acetate was selected as testing cellulose derivative for demonstrating purpose, showing their great promise for high-value use. It was proposed that the unique ionic properties of these acidic deep eutectic solvents were responsible for their selective lignin removal and cellulose swelling/deconstruction to enhance cellulose chemical reactivity. (C) 2019 Elsevier B.V. All rights reserved.
Nanocellulose (NCC) from pretreated wood and bamboo wastes was isolated by high pressure homogenization (HPH) in homogeneous media. The pretreatments included cooking with active oxygen and solid alkali (CAOSA) and bleaching with hydrogen peroxide (H2O2). Cellulose of high recovery was successfully obtained from wood and bamboo wastes with CAOSA pretreatment. The results showed that the crystallinity indices of BR-NCC and WPNCC increased to 74\% and 83\%, with a CAOSA and bleaching treatment process, respectively. NCC was homogenized at 100 MPa for 30 min, mainly in the diameter of 10 to 40 nm. The zeta potential of NCC suspensions from the two raw materials was lower than 30 mV after being placed for 7 days, which demonstrates that the suspension has good stability. Thermogravimetric analysis (TGA) indicates that the thermal stability of NCC is lower than that of raw fiber. These results prove that CAOSA assisted HPH pretreatment is an efficient and environmentally friendly means for the separation of NCC, clearly demonstrating the potential of reducing environmental pollution by the use of small amounts of nontoxic chemicals during pretreatment, especially during the bleaching process. This study first proposed the CAOSA pretreatment assisted HPH process to prepare NCC from raw biomass material. The assembled NCC was spherical and of high crystallinity.
Valuable biomass conversion processes are highly dependent on the use of effective pretreatments for lignocellulose degradation and enzymes for saccharification. Among the nowadays available treatments, chemical delignification represents a promising alternative to physical-mechanical treatments. Banana is one of the most important fruit crops around the world. After harvesting, it generates large amounts of rachis, a lignocellulosic residue, that could be used for second generation ethanol production, via saccharification and fermentation. In the present study, eight chemical pretreatments for lignin degradation (organosolv based on organic solvents, sodium hypochlorite, hypochlorous acid, hydrogen peroxide, alkaline hydrogen peroxide, and some combinations thereof) have been tested on banana rachis and the effects evaluated in terms of lignin removal, material losses, and chemical composition of pretreated material. Pretreatment based on lignin oxidation have demonstrated to reach the highest delignification yield, also in terms of monosaccharides recovery. In fact, all the delignified samples were then saccharified with enzymes (cellulase and beta-glucosidase) and hydrolysis efficiency was evaluated in terms of final sugars recovery before fermentation. Analysis of Fourier transform infrared spectra (FTIR) has been carried out on treated samples, in order to better understand the structural effects of delignification on lignocellulose. Active chlorine oxidations, hypochlorous acid in particular, were the best effective for lignin removal obtaining in the meanwhile the most promising cellulose-to-glucose conversion.
Enzyme-mediated isolation of cellulose nanocrystals (CNCs) is a promising environment friendly method with expected lower capital and operating expenditures compared to traditional processes. However, it is still poorly understood. In this study, an endoxylanase was applied as accessory enzyme to assess its potential to increase the selectivity of an endoglucanase during cellulose hydrolysis to isolate CNCs with improved properties. Only combinations of the enzymes with xylanase activity equal to or higher than the endoglucanase activity resulted in CNCs with improved properties (i.e., crystallinity, thermostability, uniformity, suspension stability and aspect ratio). The beneficial effects of the accessory enzyme are related to its hydrolytic (xylan and cellulose hydrolysis) and non-hydrolytic action (swelling of cellulose fibers and fiber porosity) and on the ratio of the enzymes, which in turn allows to tailor the properties of the CNCs. In conclusion, compared to the traditional sulfuric acid hy-drolysis method, accessory enzymes help to isolate cellulose nanomaterials with improved and customized (sizes, aspect ratio and morphology) properties that may allow for new applications.
Alfa fibers (Stipa Tenacissima) were effectively utilized in this study as a promising cellulose source for isolation of carboxy-functionalized cellulose nanofibrils (CNFs) using multiple treatments. Pure cellulose microfibers (CMFs) were firstly extracted by alkali and bleaching treatments. CNFs with an average nanofibrils diameter ranging from 1.4 to 4.6 nm and a crystallinity of 89\% were isolated from CMFs by a combination of TEMPO-oxidation and mechanical disintegration processes. The morphology and physico-chemical properties of cellulosic materials were evaluated at different stages of treatments using several characterization techniques. Various CNF loadings (5-15 wt\%) were incorporated into PVA polymer to evaluate the nanoreinforcement ability of CNFs and to produce CNF-filled PVA nanocomposite materials. The tensile and optical transmittance properties, as well as the morphological and thermal properties of the as-produced CNF-filled PVA nanocomposite films were investigated. It was found that the tensile modulus and strength of nanocomposites were gradually increased with increasing of CNF loadings, with a maximum increase of 90\% and 74\% was observed for a PVA nanocomposite containing 15 wt\% CNFs, respectively. The optical transmittance was reduced from 91\% (at 650 nm) for neat PVA polymer to 88\%, 82\% and 76\% for PVA nanocomposites containing 5, 10 and 15 wt\% CNFs, respectively. It was also found that the glass transition temperature was gradually increased from 76 degrees C for neat PVA to 89 degrees C for PVA nanocomposite containing 15 wt\%. This study demonstrates the importance of Alfa fibers as annual renewable lignocellulosic material to produce CNFs with good morphology and excellent properties. These newly developed carboxy-functionalized CNFs could be considered as a potential nanofiller candidate for the preparation of nanocomposite materials of high transparency and good mechanical properties.Graphic abstract
Cooking additive pulping technique is used in kraft mill to increase delignification degree and pulp yield. In this work, cooking additives were firstly applied in the sodium hydroxide pretreatment for improving the bioconversion of bamboo residues to monosaccharides. Meanwhile, steam explosion and sulfuric acid pretreatments were also carried out on the sample to compare their impacts on monosaccharides production. Results indicated that associating anthraquinone with sodium hydroxide pretreatment showed the best performance in improving the original carbohydrates recovery, delignification, enzymatic saccharification, and monosaccharides production. After consecutive pretreatment and enzymatic saccharification process, 347.49 g, 307.48 g, 142.93 g, and 87.15 g of monosaccharides were released from 1000 g dry bamboo residues pretreated by sodium hydroxide associating with anthraquinone, sodium hydroxide, steam explosion and sulfuric acid, respectively. The results suggested that associating cooking additive with sodium hydroxide is an effective pretreatment for bamboo residues to enhance enzymatic saccharification for monosaccharides production. (C) 2015 Elsevier Ltd. All rights reserved.
The slow pyrolysis of four biomass samples was studied by thermogravimetry (TGA) at different heating rates. The samples belonged to different botanical classes/genera, and their mineral matter content showed a high variation. A distributed activation energy model (DAEM) was used due to the complexity of the biomass samples of agricultural origin. The common features of their decomposition kinetics were sought by evaluating 12 experiments of four biomasses simultaneously by the method of least-squares. Two parallel DAEM reactions with a Gaussian distribution of the activation energies were sufficient for an acceptable fit between the experimental and simulated data. Common means and deviations of the activation energies were required for all four samples. The reactivity differences between the samples were expressed by the differences between the preexponential factors, while the weights of the parallel reactions described further differences between the samples. Altogether, 20 unknown model parameters were estimated from 12 experiments. When the method of least-squares was used on the mass loss rate (DTG) curves, one of the obtained partial curves showed a sharp peak with a small variation of E. This was associated with the cellulose decomposition. The other partial curve had a much wider E distribution and was assumed to include the decomposition of hemicellulose, lignin, and extractives. The evaluation of the sample mass (TGA) data resulted in wider partial peaks than the ones obtained from the DTG data. To exclude the possibility of any mathematical artifact, the evaluation was also carried out on the analytical integrals of the DTG curves.
The comparison of glutaric anhydride (GA) and succinic anhydride (SA) and reaction time on the surface modification of microfibrillated cellulose under a green and solvent-free technique were investigated. The degree of substitution (DS) and FTIR results showed that both anhydrides could successfully introduce carboxylate functional groups on the cellulose surface. The DS for GA and SA was 1.5 \& PLUSMN; 0.2 and 3.5 \& PLUSMN; 0.2 mmol of carboxylic acid/g of cellulose, respectively. The zeta potential results confirmed increasing surface charge from - 10.9 \& PLUSMN; 0.6 to - 23.03 \& PLUSMN; 1.7 mV for modified celluloses with GA and SA, respectively. Analysis of morphology by SEM showed all samples had fibrous structures; however, a decrease in fiber length was observed after modification. DSC results showed that carboxylation of cellulose using GA and SA caused different heat of evaporations and the onset temperature of exothermic peaks and their apex moved to lower temperatures while no significant changes in the phase transition profiles were observed. The current findings demonstrated that GA could be used as a safer and greener alternative to SA for the carboxylation of cellulose through a solvent-free and catalyst-free process.
Biofuels from lignocellulosic biomass converted via thermochemical technologies can be renewable and sustainable, which makes them promising as alternatives to conventional fossil fuels. Prior to building industrialscale thermochemical conversion plants, computational models are used to simulate process flows and conditions, conduct feasibility studies, and analyse process and business risk. This paper aims to provide an overview of the current state of the art in modelling thermochemical conversion of lignocellulosic biomass. Emphasis is given to the recent advances in artificial intelligence (AI)-based modelling that plays an increasingly important role in enhancing the performance of the models. This review shows that AI-based models offer prominent accuracy compared to thermodynamic equilibrium modelling implemented in some models. It is also evident that gasification and pyrolysis models are more matured than thermal liquefaction for lignocelluloses. Additionally, the knowledge gained and future directions in the applications of simulation and AI in process modelling are explored.
An anaerobic pneu-mechanical digester (PD) was designed to ferment lignocellulosic compounds. So, wheat and rice straws were pretreated using an ultrasound-acid, and then thermal-acid hydrolysis was conducted. Hydro-lysis optimization was performed using the response surface method and the optimal points for time, temper-ature, and acid concentration were 45 min, 148.4 ?, and 2.04 \% v/v, respectively. Cold plasma was then used as detoxification to reduce the amount of inhibitory compounds and acids. This method was capable of reducing the amounts of acetic acid, formic acid and furfural by 73, 83 and 68 \% in hydrolyzed biomass, respectively. The biomass was fermented in a PD for 20 days and compared with a conventional digester (CD). The obtained results showed that the PD could increase the efficiency of bioethanol by 37 \% in the detoxified state and 22 \% in the non-detoxified state after 20 days of fermentation compared to the CD. Moreover, H2S, CO and O-2 were measured during fermentation process. In PD, the amount of H2S and O-2 was lower than CD, but CO was significantly higher in the PD.
It is beneficial to establish a rapid prediction approach of sorption by considering various operating variables that can greatly reduce workload and minimize operational costs. In the present study, Pb(II) sorption onto synthetic biochar (BC), magnetic biochar (M-BC) and EDTA functionalized magnetic biochar (EDTA-M-BC) were comparative investigated in view of adsorption factors, adsorption kinetics and adsorption isotherm. Support vector machine (SVM) model was proposed to predict the adsorption performance by considering various operating variables. It was found that the BET surface areas of BC, M-BC and EDTA-M-BC was 499.2, 255.7 and 57.5 m(2)/g, respectively, and the majority of pores in the BC samples were mesoporous. The Pb(II) sorption processes by three kinds of BCs were well fitted to pseudo-second-order kinetic model and Langmuir model. According to zeta potential and X-ray photoelectron spectroscopy (XPS) analysis, the adsorption mechanism for Pb(II) adsorbed onto BCs were mainly attributed to electrostatic interaction and chemical complexation. The 10-fold cross-validation was performed to estimate SVM validity. The predication results showed approximately 99.4\% accuracy for test datasets and 100\% accuracy for experiment data. Thus, SVM could be a reliable accurate estimation method to predict adsorption performance.
In conventional stirred and aerated tank bioreactors, the choice of impeller type and configuration is critical to ensure suitable hydrodynamic conditions that maximize oxygen transfer while minimizing power consumption and shear rate. In this work, a systematic comparative evaluation of the performance of seven different dual-impeller configurations in a stirred tank bioreactor was carried out using Rushton turbines (RT) and Elephant Ear impellers in down-pumping (EEDP) and up-pumping (EEUP) modes. A 22 factorial design methodology was used to assess the effects of impeller speed (600-1000 rpm) and specific air flow rate (0.4-1.2 vvm) on the response variables. The EEDP-EEUP, RT-EEDP, and EEDP-RT combinations gave the best results in terms of oxygen transfer (k(L)a) and power consumption (P), with mass transfer efficiency (E-MT = k(L)a/P) up to 5.09J(-1), which was 87\% higher than for the RT-RT combination. For the selected impeller combinations (EEDP-EEUP, RT-EEDP, and RT-RT), the shear effects were quantified in terms of average shear rate (gamma(av)) and using the Kolmogorov microscale (lambda). The EEDP-EEUP dual-impeller combination proved to be the best system, with shear conditions (2174<gamma(av)(s(-1))<4287) up to 60\% lower than for the conventional RT-RT configuration. The results indicated that the EEDP-EEUP system was most suitable for the growth of shear-sensitive aerobic microorganisms, ensuring adequate mass transfer and minimizing cell damage. (C) 2016 Elsevier B.V. All rights reserved.
Choosing special materials to achieve good adsorption and capture of CO2 is an essential technique for solving the problem of global warming. Biochar is an ideal precursor CO2 adsorbent due to its renewability, stability, and useful physicochemical properties. Furthermore, heteroatom doping can significantly improve the characteristics of biochar, such as enrich heteroatom functional groups and regulate carbon skeleton. This study reviews existing heteroatom doping methods and summarizes the current understanding of the influence of heteroatoms on CO2 adsorption of biochar. Specifically, compared with different doping methods, pre-decoration doping has higher doping efficiency and creates more abundant surface functional groups than post-decoration doping. Considering multi-element co-doping can combine the special functions of each element, application advantages and potential problems of co-doping are analyzed. In addition, the study further revealed that difficulty level with heteroatom doping mainly depend on the atomic structure of the doping element. The further improvement of chemical adsorption while ensuring optimal physical adsorption will become the research focus of atom-doping-modified, biochar-based, CO2 adsorbents in the future. We believe that these summaries are valuable for systematically understanding heteroatom-doped biochar to CO2 adsorption and will serve as a theoretical support for heteroatom doping research.
This article discusses the scientific production carried out by the largest bioenergy research program in Brazil, the Sao Paulo Research Foundation Bioenergy Research Program (BIOEN-FAPESP), in the period from 2008 to 2019. The study draws on a list of BIOEN publications on the Web of Science (WoS) platform, containing over 1000 articles, grouped under ResearcherID H-6149-2012. The methods applied in the study were based on the information specific to each article and involved the construction of networks including authors, countries, research subjects, and direct citations. Communities were built based on network properties and their content was extracted from articles abstracts, titles and keywords, using text mining techniques. We also obtained quantitative measures for BIOEN scientific output. The analysis found that BIOEN produced relevant knowledge, and contributed to the emergence of new research areas in the bioenergy sector. Overall, BIOEN was decisive for the advancement of bioenergy research in Brazil, and resulted in the expansion of the knowledge base for ethanol production. (c) 2022 Society of Chemical Industry and John Wiley \& Sons, Ltd.
Microbial oil is a potential substitute for vegetable oils in the biodiesel industry. Efforts to obtain cheap carbon sources for the cultivation of lipid-producing microorganisms comprise an active research area. This work aimed to extract the hemicellulose fraction from Eucalyptus uograndis and to use its hydrolysate as a carbon source for Rhodotorula toruloides (an oleaginous yeast) cultivation for microbial oil production. Hemicellulose hydrothermal extractions were performed at different temperatures, times, and ratios of solid to liquid (S/L). Temperature and time showed a stronger effect on the solubilization of hemicellulose. Hemicellulose extraction at 155 degrees C, 195 min, and an S/L ratio of 1/2 resulted in a hydrolysate with a xylose content of 37.0 g/l. R. toruloides cultivation in this hydrolysate showed that initial pH had a strong influence on cell growth. At an initial pH of 6.2, cells grew to 6.0 g/l of biomass with a lipid content of 50\%. Therefore, we believe that E. urograndis hemicellulose hydrolysate could be a potential substrate for R. toruloides for lipid production based on the biorefinery concept.
This study focuses on development of calcium peroxide (CaO2) pretreatment that removes major part of lignin but retaining most of sugar components of kenaf core powder (KCP) biomass. In chemical pretreatment, usually higher loss of biomass occurs which was less during this pretreatment strategy. Supplementation of inorganic salts; manganese sulfate (MnSO4) and cobalt chloride (COCl2) in CaO2 pretreatment resulted in maximum delignification of KCP relative to individual CaO2 pretreatment. Maximum glucose yield (98\%) and hydrolysis yield (80.5\%) was achieved after enzymatic hydrolysis (30 FPU/g of KCP) under optimized conditions. Analytical results proved effective lignin removal and significant destruction of KCP with this pretreatment strategy. Finally, utilization of KCP enzymatic hydrolysates by developed strain Klebsiella pneumoniae KMK05 resulted in maximum 2,3-butanediol (BDO) production (10.42 g/L) and BDO titer (0.385 g/g of sugar). BDO titer achieved with KCP derived sugars were found comparable with the mixture of standard sugars which is notable.
Solid-state fermentation (SSF) is part of the pathway to consolidate waste as a relevant alternative for the valorization of organic waste. The objective of SSF is to produce one or several bioproducts of added value from solid substrates. Solid-state fermentation can use a wide variety of organic waste as substrates thus, it is an excellent candidate in the framework of the circular bioeconomy to change the status of waste from feedstock. The development of SSF was boosted in the previous decade by scientific efforts devoted to the production of hydrolytic enzymes. Nowadays, SSF has expanded to other valuable products: biosurfactants, biopesticides, aromas, pigments, and bio-flocculants, among others. This review explores the conditions to obtain the main emerging SSF products and highlight and discuss the challenges related to the scale-up of these processes and the bioproducts downstream, which hamper their further commercialization.
The food industry currently uses non-biodegradable and fossil-derived synthetic plastics materials for primary food packaging, which contribute significantly to environmental pollution. Biodegradable and biobased green nanocomposite materials with novel functionalities have been developed and are emerging on the market to minimize these environmental impacts and establish a sustainable approach towards primary food packaging. The utilization of biopolymeric materials in the packaging sector has been limited due to their poor barrier, mechanical and thermal characteristics. For improving these properties, a variety of nanomaterials such as nanocellulose can be used as a reinforcing material in biopolymeric matrices. Thus, this article provides the current state of research regarding the synthesis and characteristics of nanocellulose-based green nanocomposites along with their application in primary food packaging. Regardless of the type, the incorporation of nanocellulose has led to an improvement in mechanical, and thermal properties, a reduction in light transmittance, and improved barrier properties such as reduced oxygen permeability. In addition, nanocellulose-based nanocomposites have shown promising results in the packaging and preservation of various fruits, vegetables, and meat products. However, there is still some concern regarding the commercial utilization of nanocellulose-based material in food packaging due to a lack of regulatory standards and legislation.
Lignocellulose biomass is a unique renewable and sustainable source that can be used in energy generation, production of transport fuels and in chemical industries to replace petroleum-based resources. However, due to its recalcitrance to chemical and enzyme breakdown, it needs to be pre-treated prior to processing. In this study, ultrasound assisted ozone was used to pre-treat the agricultural processing residues corn cob and spelt husk. Following organosolv fractionation, about 90 \% and 94 \% of lignin with high purity (95 \%) were recovered for corn cob and spelt husk with guaiacyl-syringyl lignin the major fraction from corn cob and guaiacyl lignin from spelt husk respectively. In addition, cellulose pulp of 83.6 \% and 85.2 \% with 78 \% purity were recovered for corn cob and spelt husk respectively with a 19 \% decrease in cellulose crystallinity and 17 \% decrease in degree of polymerization (DP). Thus, the improved quality separation of biomass components will enhance downstream conversion to value added products thereby improving the sustainability and cost effectiveness of the process.
Olive tree pruning is a widely available and low cost lignocellulosic residue generated every year, being a potential source for bioproducts and renewable fuels production. In this context, this work has as main objective to propose an efficient scheme for the production of second generation ethanol from olive tree pruning biomass, focusing on the evaluation of different detoxification strategies (activated carbon, ammonium hydroxide and overliming) of the liquid fraction obtained after pretreatment, as well as different configurations of enzymatic hydrolysis and fermentation (including hydrolysis and sequential or simultaneous fermentation, pre-saccharification or co-fermentation) of the pretreated olive tree pruning solid. The best results of each fraction were tested in slurry, at varying initial solid loadings and aeration levels. The use of NH4OH 5N as a detoxification method and the pre-saccharification and co-fermentation configuration without aeration are proposed, resulting in 13.86 g ethanol/100 g raw material after 46 h of process.
The production of chemicals and fuels from lignocellulosic biomass has great potential industrial applications due to its economic feasibility and environmental attractiveness. However, the utilized microorganisms must be able to use all the sugars present in lignocellulosic hydrolysates, especially xylose, the second most plentiful monosaccharide on earth. Yarrowia lipolytica is a good candidate for producing various valuable products from biomass, but this yeast is unable to catabolize xylose efficiently. The development of metabolic engineering facilitated the application of Y. lipolytica as a platform for the bioconversion of xylose into various value-added products. Here, we reviewed the research progress on natural xylose-utilization pathways and their reconstruction in Y. lipolytica. The progress and emerging trends in metabolic engineering of Y. lipolytica for producing chemicals and fuels are further introduced. Finally, challenges and future perspectives of using lignocellulosic hydrolysate as substrate for Y. lipolytica are discussed.
A major challenge in converting lignocellulose to biofuel is overcoming the resistance of the biomass structure. Herein, sequential dilute acid-alkali/aqueous ammonia treatment was evaluated to enhance enzymatic hydrolysis of poplar biomass by removing hemicellulose first and then removing lignin with acid and base, respectively. The results show that glucose release in sequential dilute acid-alkali treatments (61.4-71.4 mg/g) was 7.3-24.8\% higher than sequential dilute acid-aqueous ammonia treatments (57.2-61.8 mg/g) and 283.8-346.3\% higher than control (16.0 mg/g), respectively. Dilute acid treatment removed most hemicellulose (84.9\%) of the biomass, followed by alkaline treatment with 27.5\% removal of lignin. Roughness, surface area, and micropore volume of the biomass were crucial for the enzymatic hydrolysis. Furthermore, the ultrastructure changes observed using crystallinity, Fourier transform infrared spectroscopy, thermogravimetric analysis, and pyrolysis gas chromatography/mass spectrometry support the effects of sequential dilute acid-alkali treatment. The results provide an efficient approach to facilitate a better enzymatic hydrolysis of the poplar samples.
The aim of this research is to intensify levoglucosan yield from elephant grass by fast pyrolysis and show the potential of elephant grass as a biomass to obtain other value-added byproducts. The biomass was subjected to acetic acid pretreatment at 90 degrees C prior to pyrolysis. The experiments were carried out in a GC/MS coupled with a pyroprobe reactor at 350-600 degrees C, resulting in more than 30 formed compounds including pyrolytic sugars, organic acids, ketones, aldehydes, furans, and phenolic compounds. The acid treatment contributed to hemicellulose and lignin reduction, of approximately 2 and 2.4 times, respectively. Consequently, the cellulose relative content in the biomass increased from 25.7\% to 66.6\%, contributing to an 11-fold increase in the levoglucosan content, compared to untreated biomass. Acid treatment prior to fast pyrolysis resulted essentially in the: a) removal of alkali and alkaline earth metals, confirmed by ICP, and b) biomass morphological changes confirmed by SEM, as well as probable chemical and structural changes suggested by FTIR qualitative analysis. In both cases, these results can explain levoglucosan yield increase and other changes in value-added byproduct formation observed after pyrolysis. In addition, the liquid fraction showed a reduction in the formation of oxygenated compounds, which are responsible for several undesirable properties of bio-oil as biofuel. Thus, the attained results can contribute to the development of the elephant grass agribusiness chain for energy purposes.
High-capacity crosslinked polyethylenimine (PEI)/Ca2+-Alginate fibers were fabricated as fast-kinetics adsorbents for application in gold recovery from urban mines. The benign protocols include strategic blending of PEI and alginate and extrusion into a mixture of CaCl2 and glutaraldehyde (GA) for simultaneous ionotropic gelation between the alginate and calcium ions, followed by chemical fixation of PEI into the Ca2+-Alginate matrix. Adsorption evaluation of the fabricated fibers showed remarkable gold uptakes surpassing 2300 and 1400 mg/g. The gold binding mechanisms were studied and elucidated with the aids of XRD and XPS as involving sequential electrostatic interaction and reduction by the amine, hydroxyl and aldehyde groups. The adsorption process was controlled by intra-particle diffusion mid-way towards equilibrium. The fibers were regenerated through adsorption-desorption cycles using 0.5 M thiourea/1 M HCl. The fibers demonstrated strong competiveness to existing adsorbents and have shown potentials for application as efficient adsorbents for recovery of gold from acidic solutions. (C) 2019 Elsevier Ltd. All rights reserved.
Less attention has been paid for the effects of surfactant on the hydrolysis of chitosan. This paper presents the influence of the surfactant Tween 80 addition on the chitosan hydrolysis catalyzed by cellulase enzyme. The hydrolyzed chitosan was characterized by measuring its reducing sugar content, its chemistry by Fourier transforms infrared spectroscopy (FTIR), its formation of aldehyde groups by ultraviolet - visible spectra (UV-Vis), and its crystallinity degree by X-ray diffraction (XRD). The results showed that Tween-80 could increase the hydrolysis rate and decrease the crystallinity of chitosan. The formation of reducing sugar increased by increasing reaction time up to 24 hours and then leveled off. A more significant effect of surfactant was observed when the hydrolysis was performed at a low surfactant concentration and a low substrate concentration. IR spectra showed that both raw and hydrolyzed chitosan have similar chemical structure.
This paper presents a kinetic analysis of thermal decomposition of olive tree pruning from its basic compounds in pyrolysis and combustion reactions. Experiments were performed by TGA under inert and oxidant conditions and results indicated that the decomposition of the olive tree pruning was related to the material composition. Pseudo-mechanistic models were proposed estimating the yield of pyrolysis on its basic compounds (hemicelluloses, cellulose and lignin). Validity and reliability of the proposed kinetic models were verified by the good fitting between the simulated and experimental curves (with values of R-2 higher than 0.99 in most cases). Moreover, during the fractionation process, an acid fraction was obtained with great fuel properties, a high calorific value and a low residue after its combustion.
Catalytic valorization of biomass has gained a significant global attention in recent years. Cellulose is an interesting bio-renewable feedstock, which can be utilized to replace the fossil fuel derived chemicals to attain a sustainable bio-based economy. Our research shows a one-pot conversion of cellulose through hydrolytic hydrogenation using heteropolyacid (HPA)/zirconia and Ru/C catalyst. The developed catalytic system was found to be highly active towards selective production of hexitols and ethylene glycol. A significant improvement in the catalytic performance towards cellulose conversion was observed when the cellulose was pre-treated using ballmilling (900 rpm, 8 h), as the ball-milling significantly reduced the crystallinity index of cellulose, which decreased the recalcitrance of the cellulose structure. Almost complete conversion (100\%) of cellulose was observed when the reaction was performed at 220 degrees C for 5 h giving hexitols and ethylene glycol yields of 26.2 and 40\%, respectively. Based on a series of experiments, a possible reaction pathway was proposed which suggested heteropolyacid/zirconia catalyzed hydrolysis and retro-aldol condensation reactions, accompanying by hydrogenation with Ru/C. Interestingly, HPA immobilized on the composite catalyst shows enhanced stability and recyclability, demonstrating the utilization of a heterogeneous system for tandem conversions of biomass to renewable fuels and feedstocks.
A novel composite foam was prepared from native cassava starch and water hyacinth (WH) by baking in a hot mold. The effects of WH powder content (0, 3, 5, 7 or 10 wt\%, dry starch basis) on the properties of the starch foam were investigated. A starch foam formulation with 5 wt\% WH powder exhibited the highest flexural stress at maximum load (3.42 MPa), the highest flexural strain (extension) at maximum load (3.52\%), the highest modulus (232.00 MPa), the lowest moisture content (6.77\%) and the most uniform cell size distribution (0.44 +/- 0.09 mm). Moreover, mechanical properties of starch foam with 5 wt\% WH powder were better than the same properties of some commercial foams. After being coated with beeswax, the starch foams retained their shape after immersion in distilled water and their water solubility was significantly reduced. Results indicated that a starch foam/5 wt\% WH composite with beeswax coating was a biodegradable foam that could possibly replace commercial non-degradable foam. (C) 2020 Elsevier B.V. All rights reserved.
Acidophilic beta-xylanases have attracted considerable attention due to their excellent activity under extreme acidic environments and potential industrial utilizations. In this study, a novel beta-xylanase gene (Xyl11) of glycoside hydrolase family 11, was cloned from Trichoderma asperellum ND-1 and efficiently expressed in Pichia pastoris (a 2.0-fold increase). Xyl11 displayed a maximum activity of 121.99 U/ml at pH 3.0 and 50 degrees C, and exhibited strict substrate specificity toward beechwood xylan (K-m = 9.06 mg/ml, V-max = 608.65 mu mol/min/mg). The Xyl11 retained over 80\% activity at pH 2.0-5.0 after pretreatment at 4 degrees C for 1 h. Analysis of the hydrolytic pattern revealed that Xyl11 could rapidly convert xylan to xylobiose via hydrolysis activity as well as transglycosylation. Moreover, the results of sitedirected mutagenesis suggested that the Xyl11 residues, Glu(127), Glu(164),and Glu(216) , are essential catalytic sites, with Asp(138) having an auxiliary function. Additionally, a high degree of synergy (15.02) was observed when Xyl11 was used in association with commercial beta-xylosidase. This study provided a novel acidophilic beta-xylanase that exhibits excellent characteristics and can, therefore, be considered a suitable candidate for extensive applications, especially in food and animal feed industries.
Approximately, 0.3 million tons of waste glass sludge (WGS), a by-product of plate glass manufacturing is being landfilled or discarded every year around the globe. Previously, mechanical and durability properties of burnt clay bricks incorporating WGS were reported by authors. The focus of this study is to explore the thermal properties of industrially manufactured burnt clay bricks incorporating WGS. For this purpose, WGS was obtained from a local glass cutting and polishing industry. Burnt clay bricks incorporating different dosages of WGS (i.e, 5\%, 10\%, 15\%, 20\% and 25\% by weight of clay) were prepared in an industrial kiln and were studied for different physico-mechanical and thermal properties. It was observed that dense brick specimens can be manufactured by using WGS in replacement of clay. Increase in compressive strength of clay bricks was observed after addition of WGS. Burnt clay bricks incorporating 25\% WGS showed 37\% increase in compressive strength. Reduction in apparent porosity and water absorption was also observed with increasing content of WGS in brick specimens. Microscopic images also showed dense and homogenous structure with reduced porosity after adding WGS in brick specimens, which increased the thermal conductivity of burnt clay bricks incorporating WGS. Control brick specimens showed thermal conductivity of 0.53 W/mK, which increased to 0.59 W/mK after incorporating 25\% WGS in brick specimens. However, results were observed within the thermal conductivity range (i.e., 0.4-0.7 W/mK) of traditional burnt clay bricks for masonry construction. Based on this study, utilization of WGS (up to 25\%) in the production of burnt clay bricks can be helpful in reducing the landfill and associated environmental problems of WGS. Moreover, burnt clay bricks with improved properties can be manufactured on industrial scale leading towards sustainable and cleaner production. (C) 2017 Elsevier Ltd. All rights reserved.
Starch was converted into glucose by hydrolysis with water under hydrothermal conditions at 453 - 513 K in a small batch reactor. The major product was glucose; oligomers having various degrees of polymerization, maltose, fructose, 5-hydroxymethylfurfural and furfural were also produced. The maximum yield of glucose obtained was 630 g kg(-1) on the carbon basis at 473 K and 30 min, where the quantity of carbon unrecovered was about 50 g kg(-1), and the production of char and gaseous products was negligible. (C) 2004 Society of Chemical Industry.
This work examined liquefaction of polypropylene into liquid products in the presence of ethanol with particular attention to the effect of temperature (325-400 \& nbsp;C), residence time (1-6 h) and solvent/feedstock mass ratio (1/ 1-4/1) on the overall product distribution, and composition of the oil products. The oil products obtained under the optimal reaction condition contained mainly alkanes, alkenes, alcohols and aromatics, which accounted for 42.41\%, 22.81\%, 3.51\%, 1.05\%, respectively. Increasing temperature and retention time enhanced aromatization reaction leading to increased yields of aromatic hydrocarbons. The higher heating value of the oil product was 45.72 MJ/Kg, which is comparable to the higher heating value (HHV) of gasoline. Volatility analysis shows that 50-85 wt\% of the oil composition had similar boiling point range as gasoline (35-185 C). These characterization results suggest that the oil could be used as a raw material for gasoline blendstock or chemicals. The interaction of three reaction parameters on the oil formation was further evaluated by the response surface method. Through the Box-Behnken design, the R-2, F-value and p-value of analysis of variance were 0.9917, 93.20, and < 0.0001, respectively, showed that the model fitted well with actual experimental value. It is suggested that the reaction temperature affect the oil yield more significantly, compared to other two parameters. The response surface analysis showed that under the temperature of 376.7 C, residence time 3.8 h and solvent/feedstock mass ratio of 1/1, oil yield of 98.32 wt\% can be achieved without adding catalyst or hydrogen. This predication was also verified by experiment.
A linear bacterial beta-1,3-glucan, curdlan, was functionalized by ethylenediamine tetraacetic dianhydride (EDTAD) to form a porous insoluble material (Curd-E) in this study. Various technics, including FTIR, solid state C-13 NMR, XRD, TGA, and SEM, were combined to determine the chemical and microscopic structure of the resultant. It's suggested that EDTAD esterified and cross-linked C6-hydroxyl groups of curdlan molecules to form the porous Curd-E. Moreover, Curd-E showed high adsorption capacity on Cu2+ (224.97 mg/g, pH 6.0) and Zn2+ (255.64 mg/g, pH 4.5) in comparison with the biomaterial and mineral based adsorbents. Data also indicated that the site affinity of Curd-E for cations was in the order of chelation > coordination/complexation > ion exchange. Besides, 2-site Langmuir and 2-step Freundlich isotherms gave the best interpretation for Cu2+ adsorption and Zn2+ adsorption, respectively. Since the adsorption capacity maintained 91.8\% +/- 0.8\% after five cycles of adsorption/desorption, it is believed that Curd-E is suitable for removal of divalent cations in wastewater as a novel candidate.
The objective of this study was to screen the factors that affect H-2, organic acids and alcohols production from coffee waste pretreated in a hydrothermal reactor applying consortium of bacteria and fungi (indigenous from coffee waste) with hydrolytic and fermentative activity. The effects of pH (4.0-7.0), temperature (30-50 degrees C), agitation (0-180 rpm), headspace (50-70\%), percentage of bioaugmentation (without microbial consortium to 20\%), concentration of coffee pulp and husk (2-6 g/L), coffee processing wastewater (7-30 gCOD/L) and yeast extract (0-2 g/L) were evaluated using a Plackett-Burman design. The highest H-2 production potential (82 ml H-2) was obtained under the following conditions: 30 degrees C, 180 rpm, 50\% headspace, without bioaugmentation, 2 g/L pulp and husk coffee, 30 gCOD/L coffee processing wastewater and 2 g/L yeast extract. The main soluble products were acetic acid (1956 mg/L), lactic acid (786 mg/L) and ethanol (816 mg/L). Lactobacillus sp., Clostridium sp., Saccharomyces sp. and Kazachstania sp. were the main autochthonous microorganisms identified. Through metagenome functional analysis, enzymes related to lignin, phenol, cellulose, lignocellulose, and pectin degradation were identified, as well as acidogenesis, and H-2 production. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
The isolation of biomass components with their intact structure is crucial for understanding the characteristics of biomass. Compared to other major biomass components such as cellulose and lignin, hemicellulose remains a challenging component to be isolated from the plant cell wall without significant depolymerization and modification. In this study, a novel cellulolytic enzyme-aided hemicellulose (CEH) isolation method was developed to isolate hemicellulose with a near-native branched structure from switchgrass. The structural characteristics of CEH were investigated and compared with hemicelluloses isolated by conventional alkaline extracted hemicellulose (AEH) and DMSO extracted hemicellulose (DMSOH) methods. Gel permeation chromatography (GPC) analysis indicated that CEH had a weight-average molecular weight of 44 kDa, which was comparable to that of AEH (43 kDa) but higher than that of DMSOH (37 kDa). The chemical composition analysis revealed that CEH retained a higher proportion of glucuronic acid compared to AEH and DMSOH. The 2D C-13-H-1 heteronuclear single quantum coherence (HSQC) NMR spectra containing the beta-(1,4)-linked-d-xylan backbone, non-reducing-end peaks and both alpha- and beta-reducing-end peaks in CEH were comparable to the spectra of the commercial beechwood xylan. CEH showed a highly branched hemicellulose structure, which retained methoxyl groups, O-acetyl groups, and 4-O-methyl-glucuronic acid attached to the xylan backbone.
Oil palm empty fruit bunch (EFB) is a readily available, lignocellulosic biomass that has potential to be utilized as a carbon substrate for microbial oil production. In order to evaluate the production of microbial oil from EFB, a technical study was performed through the cultivation of oleaginous micro-organisms (Rhodotorula mucilaginosa, Aspergillus oryzae, and Mucor plumbeus) on EFB hydrolyzates. EFB hydrolyzates were prepared through dilute acid pre-treatment of the biomass, where the liquid fraction of pre-treatment was detoxified and used as an EFB liquid hydrolyzate (EFBLH). The solid residue was enzymatically hydrolyzed prior to be used as an EFB enzymatic hydrolyzate (EFBEH). The highest oil concentrations were obtained from M. plumbeus (1.9 g/L of oil on EFBLH and 4.7 g/L of oil on EFBEH). In order to evaluate the feasibility of large-scale microbial oil production, a techno-economic study was performed based on the oil yields of M. plumbeus per hectare of plantation, followed by the estimation of the feedstock cost for oil production. Other oil palm biomasses (frond and trunk) were also included in this study, as it could potentially improve the economics of large-scale microbial oil production. Microbial oil from oil palm biomasses was estimated to potentially increase oil production in the palm oil industry up to 25\%, at a cheaper feedstock cost. The outcome of this study demonstrates the potential integration of microbial oil production from oil palm biomasses with existing palm oil industry (biodiesel, food and oleochemicals production), that could potentially enhance sustainability and profitability of microbial oil production. (c) 2016 Society of Chemical Industry and John Wiley \& Sons, Ltd
A magnetic biochar based adsorbent with colloidal or nanosized gamma-Fe2O3 particles embedded in porous biochar matrix was fabricated via thermal pyrolysis of FeCl3 treated biomass. The synthesized samples were studied systematically by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, selected-area electron diffraction pattern, scanning electron microscopy, energy-dispersive X-ray analysis, superconducting quantum interference device, and batch sorption measurements. The characterization analyses showed that large quantity of gamma-Fe2O3 particles with size between hundreds of nanometers and several micrometers tightly grow within the porous biochar matrix. Biochar/gamma-Fe2O3 composite exhibited excellent ferromagnetic property with a saturation magnetization of 69.2 emu/g. Batch sorption experimental results showed that the composite has strong sorption ability to aqueous arsenic. Because of its excellent ferromagnetic properties, the arsenic-laden biochar/gamma-Fe2O3 composite could be easily separated from the solution by a magnet at the end of the sorption experiment. (C) 2012 Elsevier Ltd. All rights reserved.
Co-fermentation of cheese whey (CW) and thermal-alkaline pre-treated Yerba Mate (Ilex paraguariensis) waste (YMW) was performed aiming to produce biohydrogen and/or short- and medium-chain organic acids. Central Composite Designs (CCD) was chosen as the experimental design for evaluating the combinations of three independent variables namely YMW concentration, pH and inoculum concentration in hydrogen yield (H2Y; response variable). The increase of inoculum and YMW concentrations had positive effect in biohydrogen production and yield (H2Ymax of 1.35 mmolH(2). g(-1) VSadded) whereas the initial pH had no significant effect on it. Hydrogen was produced as a coproduct to butyrate mainly. Acetate from homoacetogenesis was accounted in all conditions evaluated. The CCD also indicated operating conditions to produce moderate-to-high concentrations of short and medium-chain organic acids such as butyrate (similar to 135 mM), caproate (similar to 45 mM) and lactate (similar to 140 mM). 16S rRNA gene sequences analysis revealed five groups of microorganisms related to hydrogen, lactate and caproate production, ethanol-hydrogen co-production and hydrogen consumption.
Innovation and technology are seen today as key points in the transition to a greener and more sustainable economy. In this sense, the development of new processes able to result in reduced emissions and levels of CO2 in the atmosphere has been considered essential to support this transition and, at the same time, promote economic growth. Several techno-economic and life cycle assessment studies have shown promising data when sugars derived from lignocellulosic biomass are used as carbon source for fermentation processes. The use of CO2 as carbon source for fermentation is another smart concept for reusing this molecule while minimizing its emissions to the atmosphere. However, the large-scale implementation of biomass-based and CO2-based processes still require significant research efforts to result in robust and cost-competitive technologies. This paper discusses some promising approaches able to advance this research area including potential strategies for process intensification (enzymatic hydrolysis using high solid loading, simultaneous saccharification and fermentation, fermentation with downstream process integration), robust microbial strains for application in biomass-based and CO2-based bioprocesses, microbial co-cultivation systems, greener technologies for lignocellulosic biomass fractionation, among others. A critical evaluation of sustainability aspects including techno-economic and life cycle assessment is also provided. Overall, this study contributes with information on innovative trends able to advance the development of greener bioprocesses.
The use of agricultural residues for bioethanol production greatly depends on availability of raw materials and the proper design of a flexible multi-feedstock facility. Therefore, this article assesses the economic, environmental, and social feasibility of a bioethanol production plant, using multiple coffee crops residues (stems, pulp, and mucilage). A case study was designed for the Colombian context, considering three scenarios for different capacity plant. Results suggest that the production costs of 0.504, 0.508, and 0.515 \$USD/l for large, medium and small capacity, respectively, are comparable to the bioethanol market price and are similar to other studies reported in the literature. The CO2 emissions obtained were 1.296 Kg CO2/l, 1.297 Kg CO2/l and 1.3 Kg CO2/l for the large, medium, and small plants respectively. The large plant requires 1,170 million tons per year of fresh water, and generates a gray water footprint of 119 thousand tons per year. However, without recirculation, 2.87 times more water is required. Favorable results were identified in terms of reduction of collateral environmental effects, as well as positive impacts on social aspects. Finally, a sensitivity analysis shows the impacts of key parameters on economic, social, and environmental merits of producing bioethanol from coffee residues. (C) 2020 Elsevier Ltd. All rights reserved.
Furfural, a versatile platform compound, is produced from the hydrolysis of pentose (hemicellulose) in lignocellulosic biomass. The manufacturing of furfural results in the production and accumulation of cellulose- and lignin-rich furfural residue, simultaneously. Reasonable and effective utilization of furfural residue would provide both environmental and economic benefits. In this work, alkali cooking technology was applied to extract lignin from industrial furfural residue. The effects of different alkali treatment conditions on the composition and chemical structure of extracted lignin and solid residue were studied. The results showed that extracted lignin contained abundant guaiacyl (G), syringyl (S), andp-hydroxyphenyl (H) structural units, among which the G-type lignin structural unit accounted for the main proportion. The extracted lignin samples were rich in hydroxyl, and the highest content of hydroxyl was 4.02 mM/g under the condition of T3 (135 degrees C-0.35 M). An oxidize resistance test showed that extracted lignin showed a high inhibition effect on DPPH. The increase of lignin content in solid residue was due to the carbonization of cellulose into a lignin-like substance under the condition of a high temperature alkali treatment. This alkali cooking technology is suitable for extracting lignin from furfural residue, which has a promising application as a potential antioxidant in the food and cosmetic industry.
Cellulose nanoparticles (CNs) were prepared by acid hydrolysis of the cellulose pulp extracted from the Brazilian satintail (Imperata Brasiliensis) plant using a conventional and a total chlorine free method. Initially, a statistical design of experiment was carried out using Taguchi orthogonal array to study the hydrolysis parameters, and the main properties (crystallinity, thermal stability, morphology, and sizes) of the nanocellulose. X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), zeta potential and thermogravimetric analysis (TGA) were carried out to characterize the physical-chemical properties of the CNs obtained. Cellulose nanoparticles with diameter ranging from 10 to 60 nm and length between 150 and 250 nm were successfully obtained at sulfuric acid concentration of 64\% (m/m), temperature 35 degrees C, reaction time 75 min, and a 1:20 (g/mL) pulp-to-solution ratio. Under this condition, the Imperata Brasiliensis CNs showed good stability in suspension, crystallinity index of 65\%, and a cellulose degradation temperature of about 117 degrees C. Considering that these properties are similar to those of nanocelluloses from other lignocellulosics feedstocks, Imperata grass seems also to be a suitable source for nanocellulose production.
Fique fibers are extracted from Furcraea spp. leaves, with 5\% average mass yield, using mechanical decortication. Juice, pulp and tow, the by-products of this process, amount 95\% of the leaf weight and are considered waste. We extracted cellulose nanofibrils (CNF) from Fique tow, via ultrasound-assisted TEMPO followed by mechanical disintegration with sonication. Fique CNF exhibit diameters around 100 nm, degree of oxidation (DO) of 0.27 and surface charge density (sigma) of 1.6 mmol/g. Fique CNF aqueous suspensions show optical bi-refringence and high colloidal stability due to a high zeta potential (-53 mV). The morphology, chemical structure, crystallinity and phase transitions of Fique CNF were studied using FESEM, IR-ATR, XRD and TGA. We observed that the delignification pretreatment and the TEMPO reaction assisted by ultrasound significantly increase Fique CNF s and. potential, in contrast with the oxidation carried out without ultrasound or with raw (lignified) tow.
The removal of crude oil in saline water from microemulsion by cotton linter fiber was investigated by batch sorption. The experimental sorption data were collected without changing the water pH, biosorbent dosage (0.5 g/L), or medium rotation (140 rpm). The contact time varied from 10 min to 4.0 h and the initial crude oil concentration from 23 to 107 mg/L. The kinetics study was performed at 310 K and the sorption isotherms at 300, 310, and 320 K. Before oil sorption, the cotton linter fiber was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. A pseudo-second-order kinetic model best described the sorption process. The Freundlich isothermal model fit the batch equilibrium data well. For initial crude oil concentration at around 100 mg/L, removal efficiency of 82, 76, and 56\% was observed for sorption at temperatures of 300, 310, and 320 K, respectively. The thermodynamic parameter values demonstrate that the sorption of crude oil in saline water is spontaneous and exothermic. The results suggest that the sorption of crude oil in saline water emulsion by cotton linter fiber occurs through the surface of the rough fraction of the fiber and capillary suction due to the hollow lumens present in the fiber. The use of cotton linter fiber as a cleaning medium before discarding the produced water may cause a further decrease in the crude oil concentration flowing into the seawater bodies, below the values defined by the present legislation.
Purification is an important approach to improve the added value utilization of xylo-oligosaccharides with 2-4 degree of polymerization (XOSDP 2-4) in pre-hydrolysis liquor (PHL). In order to improve the purification efficiency of PHL, rotary evaporation was explored to promote the inhibitor removal in poplar PHL. Influence of rotary evaporation on the composition and properties of PHL were investigated. After evaporation-Ca(OH)(2)-AC purification, the xylo-oligosaccharide in the purified PHL could be used to prepare XOSDP2-4 by enzymolysis of xylanase. The results showed that there was no loss of the total xylose/xylo-oligosaccharides during the rotary evaporation process, and evaporation also promoted the removal of lignin from PHL during the subsequent Ca(OH)(2) and activated carbon (AC) treatment process, and the lignin removal increased from 57.80 \% to 71.91 \%. Furthermore, the furfural and acetic acids in PHL were separated and removed by condensation with the yields of 90.84 \% and 23.63 \%, respectively. 63.75 \% of the XOSDP (2-4) yield was obtained after rotary evaporation-Ca (OH)(2)-AC purification and enzymolysis of xylanase based on the total xylose/xylo-oligosaccharides of the purified PHL with an increase of 25.12 \% compared to the Ca(OH)(2)-AC purified PHL.
In this work, three renewable highly effective adsorbents (M-CS, M-CCL, M-CCSD) were prepared from agroforestry residues (corn stalks (CS), Cinnamomum camphora leave (CCL) and Cinnamomum camphora saw dust (CCSD)) by eco-friendly solvent-free esterification with maleic anhydride (MA) for adsorptive removal of methylene blue (MB). The three carboxyl-rich adsorbents adsorbed MB rapidly and presented remarkable adsorption performance towards MB. The maximum adsorption capacity reached 870, 741, 787 mg/g respectively according to Langmuir isotherm model. The pseudo-second-order kinetics and Langmuir isotherm models were more suitable to descript the adsorption processes of MB on M-CS, M-CCL, M-CCSD. Moreover, electrostatic attraction and ion exchange could be involved in adsorption of MB on M-CS, M-CCL, M-CCSD. The adsorption capacity of M-CS, M-CCL, M-CCSD decreased about 4\%, 4\%, 3\% respectively after 4 desorption-resorption cycles. Therefore, M-CS, M-CCL, M-CCSD can be used as sustainable and promising adsorbents with good reusability for highly effective removal of MB in effluent.
Mango seeds have been used to obtain components for nanocomposite films, namely, starch and starch nanocrystals (SNC) from seed kernels, and cellulose nanocrystals (CNC) from seed shells. Lignin was also recovered from shells. Starch-based films were prepared with different contents and combinations of SNC and CNC. SNC exhibited round-like rather than platelet-like morphology, and their effect on water vapor barrier was not as high as that of the needle-like CNC. Also, CNC were more effective than SNC to increase elastic modulus. On the other hand, CNC impaired more the elongation. The optimized conditions (1.5 wt\% CNC and 8.5 wt\% SNC on a starch basis) resulted in a film with enhanced strength, modulus, and barrier to water vapor when compared to the unfilled film, although the elongation has been impaired.
Xylitol is one of the value-added polyalcohols with diverse applications in the food, nutraceuticals, cosmetic, and pharmaceutical industries. Commercial xylitol production is extensively carried out via chemical technology through catalytic xylose dehydrogenation under high temperatures and pressure. The biotechnological synthesis of xylitol from lignocellulosic biomass is a promising and sustainable substitute for chemical xylitol synthesis, which requires strong reaction conditions and removal of the undesirable coproducts produced during the process. Numerous reviews target culture conditions and metabolic pathways in recombinant and wild xylitol-producing organisms for enhanced xylitol accretion. However, fewer studies focus on the engineering and bioprocess aspects essential for large-scale xylitol production. This review emphasizes recent advancements in xylitol bioproduction using immobilization methods. Cell immobilization improves biocatalyst reusability, stability, and tolerance against inhibitors, decreases process costs, and denotes a fundamental prerequisite for industrial application. The main immobilization techniques, mode of operations, and bioreactors employed for xylitol bioproduction using immobilization have been comprehensively summarized in this review.
The greater environmental awareness, new environmental regulations and the optimization of resources make possible the development of sustainable materials as substitutes for the traditional materials used in construction. In this work, geopolymers were developed as substitutes to traditional ceramics for brick manufacture, using as raw materials: chamotte, as a source of aluminosilicate, and biomass bottom ashes from the combustion of almond shell and alpeorujo (by-product produced in the extraction of olive oil composed of solid parts of the olive and vegetable fats), as the alkaline activator. For the feasibility study, samples were made of all possible combinations of both residues from 100\% chamotte to 100\% biomass bottom ash. The tests carried out on these sample families were the usual physical tests for ceramic materials, notably the compression strength test, as well as colorimetric tests. The freezing test was also carried out to study the in-service behavior of the different sample groups. The families with acceptable results were subjected to Fourier transform infrared (FTIR) analysis. The results of the previous tests showed that the geopolymer was indeed created for the final families and that acceptable mechanical and aging properties were obtained according to European standards. Therefore, the possibility of creating geopolymers with chamotte and biomass bottom ashes as substitutes for conventional ceramics was confirmed, developing an economical, sustainable material, without major changes in equipment and of similar quality to those traditionally used for bricks.
Solid-state fermentation (SSF) is, by definition, a technology carried out in absence or near absence of free water. Therefore, it allows the use of solid materials as substrates for further biotransformation. SSF has gained attention in the last years being reported as a promising eco-technology that allows obtaining bioproducts of industrial interest using solid biomass (wastes and by-products). Main advantages over conventional submerged fermentation rely on the lower water and energy requirements, which generate minimum residual streams. However, drawbacks related to poor homogeneity and energy and mass transfer often appear, hindering the process yield and the downstream of the produced bioproducts. Despite the difficulties, many successful processes have been reported on the production of a variety of bioproducts such as hydrolytic enzymes, mostly carbohydrases for bioethanol production, and to a lesser extent, aromas, biosurfactants, biopesticides, bioplastics, organic acids or phenolic compounds. Most of the reported research focuses on process development at small scale; however, the main challenges to overcome in SSF are related to the upscaling and the development of a consistent and continuous operation. In this work, the main advances for the production of valuable/innovative bioproducts are presented and discussed.
In this study combined NaOH/H2SO4 pretreatment of lignocellulosic biomasses (palm fronds, eucalyptus chips, almond shells and Aleppo pine cones) were used to separate hemicellulose and lignin and improve enzymatic digestibility of cellulose. The recovered celluloses were hydrolyzed using Cellic C-Tec2 or Cellic H-Tech2. The optimal saccharification yields 95.8, 94, 73.3 and 80.5\% were obtained from the recovered celluloses of palm fronds, eucalyptus chips, almond shells and Aleppo pine cones respectively using Cellic H-Tec2. The highest ethanol yield {[
Background: The enzymatic conversion of lignocellulosic biomass into fermentable sugars is a promising approach for producing renewable fuels and chemicals. However, the cost and efficiency of the fungal enzyme cocktails that are normally employed in these processes remain a significant bottleneck. A potential route to increase hydrolysis yields and thereby reduce the hydrolysis costs would be to supplement the fungal enzymes with their lacking enzymatic activities, such as beta-glucosidase. In this context, it is not clear from the literature whether recombinant E. coli could be a cost-effective platform for the production of some of these low-value enzymes, especially in the case of on-site production. Here, we present a conceptual design and techno-economic evaluation of the production of a low-cost industrial enzyme using recombinant E. coli. Results: In a simulated baseline scenario for beta-glucosidase demand in a hypothetical second-generation ethanol (2G) plant in Brazil, we found that the production cost (316 US\$/kg) was higher than what is commonly assumed in the literature for fungal enzymes, owing especially to the facility-dependent costs (45\%) and to consumables (23\%) and raw materials (25\%). Sensitivity analyses of process scale, inoculation volume, and volumetric productivity indicated that optimized conditions may promote a dramatic reduction in enzyme cost and also revealed the most relevant factors affecting production costs. Conclusions: Despite the considerable technical and economic uncertainties that surround 2G ethanol and the large-scale production of low-cost recombinant enzymes, this work sheds light on some relevant questions and supports future studies in this field. In particular, we conclude that process optimization, on many fronts, may strongly reduce the costs of E. coli recombinant enzymes, in the context of tailor-made enzymatic cocktails for 2G ethanol production.
Fruits-and-vegetables wastes (FVW) and corn stover (CS) are two of the most recurred lignocellulosic biomasses used for biofuel production. In this work, the co-processing of FVW and CS for biohydrogen production was proposed and evaluated through a set of experimental designs. First, a 5. 2 general factorial was applied on the dilute acid pretreatment at five levels of FVW:CS ratios (0:1, 1:3, 1:1, 3:1 and 1:0 dry mass basis) and two levels of the type of catalyst (HCl or H2SO4 at 0.5\% in volumetric basis). Then, biohydrogen production using the dilute acid hydrolyzates was carried out in batch mode at 35 degrees C in a 32 factorial design, the factors being the inoculum to substrate ratio (0.8, 1.0, and 1.2 g g(-1)) and the initial concentration of reducing sugars (10, 13 and 16 g L-1). The effects of the type of acid catalyst and the FVW:CS ratio were significant in terms of sugars production and yield. The best catalyst was HCl for the 3:1 FVW:CS ratio, which produced monomeric sugars concentrations of 10.0, 3.7 and 2.9 g L-1 for glucose, xylose and arabinose, respectively. The hydrolyzates were suitable for biohydrogen production, reaching yields of 2.31 mol H-2 mol(-1)glucose and hydrogen production rates of 8.83 mL H-2 h(-1). An economic prospection at lab scale demonstrated that hydrogen production presented net revenues of 0.009 USD per kg of co-substrates, resulting in 24\% profitability of hydrogen production over its production costs. Therefore, this co-processing is an interesting proposal with further applications on biorefinery models.
The limited reactivity of starch towards maleic anhydride (MA) affords maleate with a low degree of MA substitutions (-C=C- and -COOH groups). In this study, we investigated the relationship between the starch structure, controlled by its amylose (AM)/amylopectin (AP) ratio, and the DS of starch maleates using C-4{[
Phalaris aquatica L., a rich in holocellulose (69.80 \%) and deficient in lignin (6.70 \%) herbaceous, perennial grass species, was utilized in a two-step (biomass pretreatment-enzymatic hydrolysis) saccharification process for sugars recovery. The Taguchi methodology was employed to determine the dilute acid pretreatment and enzymatic hydrolysis conditions that optimized hemicellulose conversion (75.04 \%), minimized the production of inhibitory compounds (1.41 g/L), and maximized the cellulose to glucose yield (69.69 \%) of mixed particulate biomass (particles < 1000 mu m) under batch conditions. The effect of biomass particle size on saccharification process efficiency was also investigated. It was found that small-size biomass particles (53-106 mu m) resulted in maximum hemicellulose conversion (81.12 \%) and cellulose to glucose yield (93.24 \%). The determined optimal conditions were then applied to a combined batch pretreatment process followed by a fed-batch enzymatic hydrolysis process that maximized glucose concentration (62.24 g/L) and yield (92.48 \%). The overall efficiency of the saccharification process was 88.13 \%.
Thousands of oil spill incidents regrettably have occurred on a daily basis around the globe. Oil spills are a form of pollution that poses major catastrophic threats to marine ecosystems. Oil spill incidents commonly occur in the middle of the ocean, and the process to remove the oil becomes a great challenge. Absorbents, due to their good oil-absorbing characteristics, are becoming more popular nowadays as one of the effective oil spill clean-up methods. Among the many types of oil absorbents, plant fibers were also being studied to remove the oil spills from the sea surface. This paper reviews factors leading to oil spills, the detrimental effect of the oil spill on the environment, the oil spill removal methods, and the application of plant fibers as oil absorbent material. The paper also will highlight the latest development on the utilization of kenaf core fibers as oil-absorbent material and the use of oil absorbed kenaf core fibers as fuel briquette by taking advantage the high calorific value of the oil spill.
In the wake of developing a sustainable future, the valorization of abundant, eco-friendly, and renewable lignocellulose resources is of immense importance. The pretreatment of lignocellulose is inevitably an important step for getting value-added products as the complicated structure of biomass defies its effectual utilization. Compared to conventional pretreatment technologies that have negative impacts on the environment, ionic liquids have emerged as promising green solvents with a cutting-edge influence in lignocellulose processing. Ionic liquids have the capability of replacing conventional chemicals and solvents owing to their distinctive physical, biological, chemical, and thermal attributes. The tunable properties of ionic liquids have an impeccable impact on numerous applications, especially on the lignocellulose pretreatment and direct conversion into biochemicals and biofuels. The major motivation of this review is to provide a detailed discussion on the cleaner deconstruction and dissolution mechanism, the effect of different anions and cations, and the direct conversion of lignocellulose in valued chemicals (total reducing sugars, 5-Hydroxymethylfurfural, and levulinic acid). Based on this review, some identified research gaps, including the synthesis of low-cost ionic liquids, ionic liquids/co-solvent combinations, and ionic liquid pretreatment process integration, are needed to be further discussed in the future.
This paper presents the results of experimental study on the production of particle boards from wastes of wood and expanded polystyrene foam (EPS). Two different particle sizes of wood wastes and two different dosages of EPS resin were used as binders in the boards (WPP). Modulus of rupture (MOR), modulus of elasticity (MOE) and physical properties were analysed. Effects of long-term immersion in water for 7-28 days on the properties of the particleboards were similarly evaluated. SEM and FTIR were used to analyse the specimens. The results showed that water absorption decreased as EPS content was increased from 1.5 to 2.0 and thickness swelling indicated that WPP with 0.85 mm particle sizes and 1.5 resin dosages had the least value between 2.38 and 3.51\% after 7-28 days of prolonged immersion in water. MOR and MOE indicated that the optimum performances of the WPP boards were recorded before the prolonged immersion in water at 4.3 MPa and 187.8 MPa. WPP with 0.85 and 1.75 mm particle sizes with 2.0 resin dosage had good post immersion performance. This study demonstrated that wood and EPS wastes are sustainable materials for producing composite wood based panels that are still durable in moist environment.
Rice husk as an abundant biomass was used in this study, and it contained 30.1\% glucan and 13.5\% xylan, 22.4\% lignin. The pretreated rice husk with glycerol carbonate and acidified aqueous glycerol (10\% water) at 90 degrees C and 130 degrees C for 60 min had the maximum yield of glucan digestibility which was 78.2\% and 69.7\% respectively, using cellulase for 72 h. The simultaneous saccharification and fermentation was conducted anaerobically at 37 degrees C with Saccharomyces cerevisiae, 5\% w/v glucan and 10 FPU/g glucan of cellulase. 11.58 and 8.84 g/L was the highest ethanol concentration after 3 days of incubation form pretreated rice husk with glycerol carbonate and acidified aqueous glycerol respectively. (C) 2017 Elsevier Ltd. All rights reserved.
Biochar has attracted much research attention recently because of its potential applications in many environmental areas. In this work, the biochar technology was combined with the emerging graphene technology to create a new engineered graphene-coated biochar from cotton wood. The biomass feedstock was first treated with graphene/pyrene-derivative and was then annealed at 600 degrees C in a quartz tube furnace under N-2 environment. Laboratory characterization with different microscopy and spectrometry tools showed that the graphene sheets were ``soldered{''
We investigated the performance of fluidized and packed-bed bioreactors using cells of Spathaspora passalidarum UFMG-CM-469 immobilized on LentiKats (R) in the fermentation of lignocellulosic biomass hydrolysates. Acid (AH-CYE) and enzymatic (EH-CYE) hydrolyses of a 1:1 mixture of oat and soybean hulls, minimally supplemented with crude yeast extract, were used as substrates. Continuous cultures at dilution rate (D) of 0.05 h(-1) were run in the fluidized and packed-bed bioreactors, using both AH-CYE and EH-CYE, showing ethanol yields varying from 0.30 to 0.45 g.g(-1) and productivities from 0.39 and 0.99 g.(L.h)(-1). Continuous cultures in the fluidized bioreactor, which proved to be better than the packed bed, operating at higher dilution rates of 0.1 h(-1) and 0.2 h(-1) increased ethanol productivity, reaching 1.67 g.(L.h)(-1) when using AH-CYE and 2.65 g.(L.h)(-1) with EH-CYE. These results show the possibility of exploring the fermentation of lignocellulosic biomass hydrolysates in continuous cultures of immobilized S. passalidarum UFMG-CM-469 to produce second-generation ethanol under a concept of biorefinery.
Phytasae enzymes have a major role in animal feed applications as they help in the bioavailability of phosphorus present in phytic acid, an anti-nutritional compound associated with higher plant proteins. However, achieving higher levels of phytase production and phytic acid degradation is still difficult in solid state fermentation (SSF). This study involved a comparison of ultrasonication treated and untreated rice bran (RB) to improve the phytase production using Rhizopus sp. Ultrasound treatment of rice bran has been optimized with different parameters such as ultrasound time, ultrasound cycle (UC), ultrasound amplitude and liquid to solid ratio (LSR). With optimal conditions of treated RB (40 min ultrasound time, 100\% ultrasound cycle (no intervals during ultra-sound), 40:10 (mL/g) LSR and 80\% ultrasound amplitude), a 9.3-fold increase in phytase production was observed. Different analytical methods were used to study the characteristics of treated and untreated RB such as scanning electron microscope (SEM) for morphological changes, functional group modifications using Fourier transform infrared spectroscopy (FTIR), elemental composition using energy dispersive analysis of X-rays and the crystalline nature using X-ray diffraction (XRD). With optimized conditions, phytase production was carried out and its potential activity with simulated gastric fluids were studied at pH 2.0-5.0. The thermostability of the phytase enzyme was further improved by the addition of polyvinylpyrrolidone (PVP). Thus, the ultrasound treated RB can be a potential substrate for the efficient production of phytase and as a source for a nutritive supplement that might be used in the food and feed industries.
The intrinsic recalcitrance of lignocellulosic biomass makes it resistant to enzymatic hydrolysis. The electron-rich surface of the lignin and cellulose-alike structure of hemicellulose competitively absorb the cellulase. Thus, modifying the surface charge on biomass components to alter cellulase affinity is an urgent requisite. Developing charge tunable cellulase will alter substrate affinity. Also, charge-based immobilization generates controllable substrate affinity. Within immobilized cellulase involved in situ biomass saccharification, charge effects made a crucial contribution. In addition to affecting the interaction between immobilized cellulase and biomass, charge exerts an impact on cellulase to immobilize the materials, further investigation is essential. This study aims to review the charge effects on the cellulase affinity in biomass saccharification, strategies of charge tunable cellulase, and immobilized cellulase, thereby explaining the role of electrostatic interaction. In terms of electrostatic behavior, the pathways and plans to improve in situ biomass saccharification seem to be promising.
Plantain and chayotextle starch were mixed with plantain and chayotextle fiber to make biodegradable materials through a baking process. Tensile strength (Ts) and Young module (Ym) in baked foam materials (BFM) improved as the concentration of fiber increased, while elongation at break (Eb) decreased. BFM made only with plantain or chayotextle starch showed poor mechanical properties. Density values increased from similar to 0.16 to similar to 0.26 g/cm(3)when the concentration of fiber in the matrix of the BFM increased while solubility decreased with higher fiber content. In burial tests, biodegradation of BFM was observed over time as indicated by the loss of weight and a reduction in the transition peaks obtained in the thermogravimetric analysis. The mineralization study showed that the addition of fiber decreased the biodegradation rate of the BFM compared to samples made only of starch. Based on the results, plantain and chayotextle fiber which is a waste byproduct could be used to produce biodegradable materials for food packaging and help reducing the need for plastic materials.
Recycled pulp can be used as a potential and sustainable resource for production of fermentable monosaccharides. In this work, the effects of residual lignin and thermal drying on ultrastructure, physical properties and further enzymatic digestibility of chemical pulps were investigated. The results showed that drying process (at 105 degrees C for 24h) did not significantly change the functional groups but it resulted in increased cellulose crystallinity and fibril aggregation, pore shrinkage and decreased swelling ability of fibers. On the other hand, residual lignin (3\%) in unbleached pulp restrained partially the deterioration of those properties during drying, compared to bleached pulp (lignin content 0.3\%). Compared with once-dried bleached pulp, the unbleached pulp after drying had a slightly higher proportion of amorphous region, higher average pore size and specific surface area, and lower hornification degree, which are favorable for enzymatic hydrolysis. Moreover, the fibrils may have wrapped the lignin when they aggregated, reducing the unfavorable adsorption of lignin to cellulase. Enzymolysis also showed that the once-dried unbleached pulp was much easier to digest, and yielded 66\% glucose after 12-h hydrolysis, which was much higher than the yield (54\%) of the once-dried bleached pulp and should have good prospects. {[
Selective biomass fractionation into carbohydrates and lignin is a key challenge in the conversion of lignocellulosic biomass to fuels and chemicals. In the present study, alkaline hydrogen peroxide (AHP) pretreatment was investigated to fractionate lignin from polysaccharides in corn stover (CS), with a particular emphasis on the fate of the lignin for subsequent valorization. The influence of peroxide loading on delignification during AHP pretreatment was examined over the range of 30-500 mg H2O2/g dry CS at 50 degrees C for 3 h. Mass balances were conducted on the solid and liquid fractions generated after pretreatment for each of the three primary components, lignin, hemicellulose, and cellulose. Al-1P pretreatment at 250 mg H2O2/g dry CS resulted in the pretreated solids with more than 80\% delignification consequently enriching the carbohydrate fraction to >90\%. Twodimensional nuclear magnetic resonance (2D-NMR) spectroscopy of the AI-IP pretreated residue shows that, under high peroxide loadings (>250 mg H2O2/g dry CS), most of the side chain structures were oxidized and the aryl-ether bonds in lignin were partially cleaved, resulting in significant delignification of the pretreated residues. Gel permeation chromatography (GPC) analysis shows that AHP pretreatment effectively depolymerizes CS lignin into low molecular weight (LMW) lignin fragments in the aqueous fraction. Imaging of AHP pretreated residues shows a more granular texture and a clear lamellar pattern in secondary walls, indicative of layers of varying lignin removal or relocalization. Enzymatic hydrolysis of this pretreated residue at 20 mg/g of glucan resulted in 90\% and 80\% yields of glucose and xylose, respectively, after 120 h. Overall, Al-1P pretreatment is able to selectively remove more than 80\% of the lignin from biomass in a form that has potential for downstream valorization processes and enriches the solid pulp into a highly digestible material.
The continuous production of furfural using vaporization reactor as a continuous stirred tank reactor is reported in this study. 50 g L-1 xylose solution was continuous fed into the reactor and catalyzed by 2 wt\% H2SO4 at 433 K gave 82.3\% average yield of furfural in 10 h of reaction time. Pulp prehydrolysate derives from prehydrolysis of wood biomass was further used as the raw material for the reaction, and the 78.6\% average yield of furfural was achieved for 10 h. According to Aspen Plus simulation, 11.7 tons of saturated steam was required for the production of one ton of furfural under the present reaction system, which is almost half of the traditional one-step method.
Fast microwave-assisted co-pyrolysis of pretreated bamboo sawdust and soapstock was conducted. The pretreatment process was carried out under microwave irradiation. The effects of microwave irradiation temperature, irradiation time, and concentration of hydrochloric acid on product distribution from co-pyrolysis and the relative contents of the major components in bio-oil were investigated. A maximum bio-oil yield of 40.00 wt. \% was obtained at 200 degrees C for 60 min with 0.5 M hydrochloric acid. As pretreatment temperature, reaction time and acid concentration increased, respectively, the relative contents of phenols, diesel fraction (C12 + aliphatics), and other oxygenates decreased. The gasoline fraction (including C5-C12 aliphatics and aromatics) ranged from 55.77\% to 73.30\% under various pretreatment conditions. Therefore, excessive reaction time and concentration of acid are not beneficial to upgrading bio-oil.
Pretreatment of biomass with dilute acid requires high temperatures of >160 degrees C to remove xylan and does not remove lignin. Here we report that the addition of peracetic acid, a strong oxidant, to mild dilute acid pretreatment reduces the temperature requirement to only 120 degrees C. Pretreatment of yellow poplar with peracetic acid (300 mM, 2.3 wt\%) and dilute sulfuric acid (100 mM, 1.0 wt\%) at 120 degrees C for 5 min removed 85.7\% of the xylan and 90.4\% of the lignin leaving a solid consisting of 75.6\% glucan, 6.0\% xylan and 4.7\% lignin. Low enzyme loadings of 5 FPU/g glucan and 10 pNPGU/g glucan converted this solid to glucose with an 84.0\% yield. This amount of glucose was 2.5 times higher than with dilute acid-pretreated solid and 13.8 times higher than with untreated yellow poplar. Thus, the addition of peracetic acid, easily generated from acetic acid and hydrogen peroxide, dramatically increases the effectiveness of dilute acid pretreatment of biomass.
Improvement of concrete strength owing to confinement by lateral reinforcement is disregarded in the current concrete design practice. The focus of this study is to use the pre-existing lateral reinforcement to enhance the behaviour of recycled aggregate concrete (RAC). The stress strain performance of steel spiral confined concrete specimens with different confinement pressure, recycled aggregates (RA) replacement ratio and target strength is studied. The results show a decrease in compressive strength of concrete with the rise in RA replacement ratio. Around 43, 37 and 33\% drop in the strength is observed for 100\% RA replacement ratio having different target strengths of NAC (i.e., 25, 40 and 60 MPa). However, steel confinement has a positive role to offset the negative effect of RA on strength. The rise in the confinement pressure results in improved ductility and stress strain behaviour of RAC. Due to scant research work related to steel spiral confined RAC, existing models cannot estimate the stress strain performance of steel spiral confined RAC effectively. Therefore, a new model is developed in this study, considering a large experimental program. The newly developed model can be effectively used to predict the stress strain performance of both steel spiral confined normal aggregate concrete and RAC, which provides guidelines for the design of RAC members. Furthermore, a relationship is also developed to determine the allowable content of RA for given confinement without affecting the concrete strength, which may be used to decide the allowable content of RA in designing the RAC compression members.
In the present study, Kluyveromyces marxianus was utilized to study the batch fermentation kinetics of biomass production, substrate utilization and bioethanol production from woody stem Prosopis juliflora. The pre-treated substrate was subjected to Simultaneous Saccharification and Fermentation (SSF) under optimised conditions of pH (4.9), temperature (41 degrees C), substrate concentration 5\% (w/v), inoculum concentration 3\% (v/v) and the maximum concentration of bioethanol was found to be 21.45 g/l. The experimental data thus obtained from cell growth, substrate utilization and product formation are employed in the determination of kinetic parameters. Biological models such as Logistic model, Hinshelwood model were used for microbial growth and substrate utilization kinetics respectively. In case of product kinetics, Leudking-Piret plot, Gompertz model and Modified Gompertz model were utilised. Based on these models, kinetic parameters like maximum specific growth rate (mu m), saturation constant (Ks), growth associated (alpha), non-growth associated (beta) and yield coefficients (Y-X/S, Y-P/S) were estimated.
Due to its renewability, availability and high cellulose content (approximate to 45\%), Alfa fibers (Stipa tenacissima) have been identified as a sustainable source for cellulose microfibers (CMF) and cellulose nanocrystals (CNC) production. Subjecting raw Alfa fibers to alkali, bleaching and sulfuric acid hydrolysis treatments allowed producing CMF and CNC with high yields. The fluorescence microscopy confirmed that CMF, with average diameter of 10 mu m, were successfully obtained after bleaching treatments. TEM and AFM showed that the CNC exhibit needle-like shape with an average diameter and length of 5 +/- 3 nm and 330 +/- 30 nm, respectively, giving rise to an aspect ratio of about 66. XPS measurement confirmed the presence of sulfate groups on the surface of CNC with 2.04 sulfate groups per 100 anhydroglucose units, confirming the negatively charged surface of CNC, with zeta potential value of - 47.39 mV. XRD studies showed that CMF and CNC exhibit cellulose I structure with crystallinity index of 71\% and 90\%, respectively. FT1R and TGA analyses were used to identify the chemical composition and thermal stability changes during different chemical treatments, suggesting that all non-cellulosic compounds were removed after alkali and bleaching treatments. The obtained CNC were dispersed into three different biopolymer matrices, e.g. chitosan, alginate, and k-carrageenan, at various CNC loadings (1, 3, 5 and 8 wt\%), to evaluate their ability to enhance the tensile properties of biopolymers and, at the same time, to produce new biopolymer-based nanocomposite films. It was found that the tensile properties of the as-produced nanocomposite films were largely improved with addition of CNC, resulting in mechanically strong and flexible ecofriendly nanocomposite films.
The European Green Deal emerged as a package of policy initiatives for a green transition, aiming to reach climate neutrality by 2050. Accordingly, the pulp and paper industry has been focused on upgrading residues into value-added products within the forest-based circular economy business model. In this context, this study considered the possibility of using bark, a residue available in high volume on factory floors, for cellulosic ethanol production instead of typical burning for energy generation. Bioconversion of lignocellulosic polysaccharides of bark is a challenge and simultaneous saccharification and fermentation (SSF) setup was chosen to boost cellulosic ethanol production. The introduction of a short pre-saccharification (PS) stage (0, 1 and 4 h) in bioethanol production from Eucalyptus globulus bark, previously submitted to a kraft pretreatment, following an integrated configuration, PS-SSF, at the bioreactor scale improved bioethanol concentration. It was observed that the longer pre-saccharification, the higher productivity. Shifting from this batch PS-SSF (4 h) to a fed-batch PSSSF (4 h) configuration allowed to increase the solids loading from 8\% to 20\% (w/v), raising the final bioethanol concentration from 27.4 to 75.9 g L-1, and improving by itself the overall productivity more than 25\%. These results show that in the pulp and paper mills, an integrated biorefinery should be considered to foster the total resources use within the circular economy model.
Abies bornmulleriana cone was used to investigate its biosorption efficiency and capacity of Pb2+, Cu2+, Cd2+, Co2+, and Ni2+ heavy metal ions in a quinary system. The mechanism of multi-metal removal was illustrated in terms of FTIR results. Electrophoretic mobilities of the biosorbents were determined to access the information about the competitive biosorption. BET surface area and pore volume of the biosorbents before and after the biosorption were defined to be (5.05 m(2) g(-1) and 0.0018 cm(3) g(-1)) and (0.97 m(2) g(-1) and 0.00032 cm(3) g(-1)), respectively. The average pore width of the biosorbent before and after the biosorption was calculated as 9.34 and 13.04 A, respectively. The pseudo-first-order model and the pseudo-second-order model were applied to analyze the experimental data. Experimental data have been evaluated according to the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms. The maximum biosorption efficiency and capacity for Pb2+, Cu2+, Cd2+, Ni2+, and Co2+ ions were defined as (85.4, 56.4, 35.4, 21.7 and 18.9\%) and (8.5, 5.6, 3.5, 2.2 and 1.9 mg g(-1)), respectively. The selectivity of heavy metal ions resulted in the magnitude order of Pb2+ > Cu2+ > Cd2+ > Ni2+ > Co2+.
A considerable amount of volatile solids (VS) contained in the biomass of microalgae makes it promising for use as feedstock in fermentation processes. In this study, a biomass of microalga Chlorella sp. was used as a sole substrate for hydrogen production in an anaerobic solid-state fermentation (ASSF). Optimization of the process was investigated on the selected critical variables, i.e., total solid (TS) content, initial pH, and feed to inoculum (F/I) ratio (on a VS basis) using response surface methodology (RSM) with central composite design (CCD). TS content and F/I ratio were found to have statistically significant effects on hydrogen production. Maximal hydrogen production of 165 +/- 12 mL H-2, equivalent to 18.58 mL H-2/g VS and 0.28 L H-2/L reactor d, was achieved under the optimal conditions of 38.83\% TS, pH 6.03, and an F/I ratio of 4.33. Acetic and butyric acids were found to be main soluble microbial products (SMPs) in the fermented biomass. Based on the compositions of the biomass, an equation for theoretical bioconversion of Chlorella sp. biomass to hydrogen was proposed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
One substantial plant waste, lotus leave was fabricated into lotus leave powder with different diameters by ball milling. The surface morphology, chemical composition, particle size, porosity parameters, crystal structure, and wettability of lotus leaf powders (LLPs) were analyzed by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), laser particle size analysis, N2 adsorption/desorption, X-ray diffraction (XRD) analysis, and water contact angle (WCA) analysis, respectively. The results showed that the micro- and nanoscale waxy papilla structures on the surface of the lotus leaf were gradually destroyed by mechanical forces along with extended balling time. Accompanied re-exposing of -OH affluent cellulose nanocrystals (CNCs) was proved by HR-TEM, XRD, and FTIR. FTIR also revealed a hydroxyl to carboxyl transition on the surface of CNCs. Both the re-exposure of CNCs and thereof chemical structure transition after ball milling made the LLP a good candidate for pollutant adsorbent for dye, formaldehyde, and heavy metal ions.
Homogeneous esterification of cellulose, which can control the molecular structure of the resultant cellulose esters and facilitate the versatility of cellulose-based materials, has drawn much attention. Recently, the advent of room temperature ionic liquids (ILs) capable of dissolving cellulose has provided a new and versatile platform for the efficient and homogeneous esterification of cellulose. A variety of conventional, novel and functional cellulose esters have been successfully synthesized in ILs. Meanwhile, development of esterification techniques, utilization of agricultural residues and up-scaling of pilot schemes of esterification in ILs have been in progress. This review summarizes the advances and developments in homogeneous synthesis of cellulose esters in ILs in recent decades. (c) 2015 Society of Chemical Industry
In this study, three different pretreatment technologies (hydrothermal, NaOH, and ethylenediamine (EDA) pretreatment) were investigated to improve the efficiency of the enzymatic conversion of Caragana korshinskii Kom. (CKK). The effects of the pretreatment conditions on the composition, structure, and enzymatic hydrolysis of CKK were evaluated. The results indicated that EDA pretreatment was more effective in promoting CKK digestibility than the other pretreatments. EDA exhibited a good delignification ability (up to 72.8\%) and a strong de-crystallization effect (up to 29.9\%) compared to hydrothermal and NaOH pretreatment. The best result for the cellulose enzymatic conversion (88.0\%) was obtained at 210 ?C for 40 min with 30 mL EDA. Using of the EDApretreated CKK as a substrate for bacterial cellulose (BC) production indicated that a lower nutrient level in the enzymatic hydrolysate medium could be a key factor that impedes the fermentation performance of Gluconacetobacter xylinus. The addition of extra nutrients promoted BC production efficiency, and under optimized conditions, the BC yield was 4.6 g/L.
For improving the economic efficiency of the biorefining concept, selective decomposition and separation of biomass components is indispensable. In this respect, a sequential pretreatment process consisting of liquid hot water treatment and diluted peracetic acid (PAA) treatment was proposed for total utilization of lignocellulosic woody biomass. During the liquid hot water treatment, hemicellulose can be decomposed efficiently without significant loss of cellulose and lignin, implying the possibility for xylooligomer production by thermochemical treatment. In the PAA treatment, lignin was successfully degraded and liquefied using a 50\% diluted PAA solvent, suggesting the possibility of dicarboxylic acid production. After the sequential process proposed in this study, the cellulose accessibility to the enzyme could be maximized by inducing selective deconstruction of hemicellulose and lignin.
Sugars derived from biomass hemicelluloses, especially pentoses, have low value because they are generally not suitable for industrial fermentation processes. In contrast, dehydration of xylose, one of the main constituents of hemicelluloses, yields furfural. The dehydration process is relatively simple, and furfural has several applications mainly in the polymer and lubricant industries. Moreover, chemical upgrade of furfural can yield 2-methyltetrahydrofuran (MTHF) and ethyl levulinate (EL), two chemicals that can be used as fuel additives in gasoline and diesel, respectively. In this work, three chemical upgrading routes for furfural were proposed and simulated based on process data available in the literature. The economic analysis showed the feasibility of producing MTHF in a two-step hydrogenation process, in four geographic regions (Brazil, China, European Union, and the United States). The maximum furfural price to allow profits at a minimum acceptable rate of return of 10\% is \$457 Mg--(1). On the other hand, the conversion of furfural to ethyl levulinate is not economically attractive mainly because of its lower energy density, which resulted in a low selling price. This study also discussed the need for new catalysts to avoid high hydrogen to furfural ratios while enabling hydrogenation at high pressures. These operating conditions were found to be major technoeconomic hurdles for the chemical upgrade of biomass-derived furfural to MTHF and EL.
An empty oil-palm fruit bunch (EFB) has been proposed as an alternative lignocellulose with potential to produce bio-succinate. However, studies of succinate production from EFB were sparse. Succinate concentrations and yield reported in published literatures were still low. To be more attractive, the utilization of EFB for bio-succinate at high concentrations and yields was demonstrated in this study. EFB was thermochemically pretreated employing diluted H2SO4, 121 degrees C for 30 min. After pretreatment, detoxification of EFB black-liquor hemicellulosic hydrolysate exploiting 0.5\%(w/v) activated carbon could remove 92.04\% furfural and 100\% HMF derived from degraded sugars and fatty acids in EFB. Removals of 76.4\% acetate and 95.80\% phenols from the activated carbon-treated hydrolysate were further achieved by vacuum distillation. The 70\%(v/v) detoxified hydrolysate showed the least inhibitory effect on succinate production at the level of 54.8 +/- 1.5 g/L by Escherichia coli KJ12201-14 T. Alternatively, 70 g/L acid-pretreated EFB cellulosic solid was hydrolyzed with minimized cellulase and beta-glucosidase at a ratio of 15FPU:10CBU/g to release fermentable sugars at 94.02\% recovery to produce 32.3 +/- 1.6 g/L succinate. A combined fraction of 50\%(v/v) detoxified EFB hydrolysate and 70 g/L cellulosic EFB solid was additionally utilized to produce succinate at 72.5 +/- 0.8 g/L with a yield of 0.83 +/- 0.02 g/g. These concentration and yield attained were highest than those of previous literatures. Our fermentation differs from published reports in the application of low inorganic-salts medium (0.9 g/L) without supplementation of any rich nutrients. These may reduce costs of medium, purification, energy consumption, and waste disposal. Our developed process may be an economically feasible option for future industrial succinate production.
The interest in bioprinting of sustainable biomaterials is rapidly growing, and lignocellulosic biomaterials have a unique role in this development. Lignocellulosic materials are biocompatible and possess tunable mechanical properties, and therefore promising for use in the field of 3D-printed biomaterials. This review aims to spotlight the recent progress on the application of different lignocellulosic materials (cellulose, hemicellulose, and lignin) from various sources (wood, bacteria, and fungi) in different forms (including nanocrystals and nanofibers in 3D bioprinting). Their crystallinity, leading to water insolubility and the presence of suspended nanostructures, makes these polymers stand out among hydrogel-forming biomaterials. These unique structures give rise to favorable properties such as high ink viscosity and strength and toughness of the final hydrogel, even when used at low concentrations. In this review, the application of lignocellulosic polymers with other components in inks is reported for 3D bioprinting and identified supercritical CO2 as a potential sterilization method for 3D-printed cellulosic materials. This review also focuses on the areas of potential development by highlighting the opportunities and unmet challenges such as the need for standardization of the production, biocompatibility, and biodegradability of the cellulosic materials that underscore the direction of future research into the 3D biofabrication of cellulose-based biomaterials.
Accumulation of residual plastics and the biomass wastes from agricultural sectors are causing serious global environmental problems if not addressed effectively. Cellulose with polypropylene as biocomposite material is an elegant strategy for value-added utilization of wastes. In this study, green isolation of cellulose from oil palm empty fruit bunches by autoclave-based and ultrasonication pre-treatments were developed to replace the non-green chlorite method. Ultrasonic treatment with hydrogen peroxide yielded 49\% cellulose with 9.13\% alpha-cellulose content and 68.7\% crystallinity, as compared to 64\% cellulose with autoclave treatment. Based on field emission scanning electron microscope, the ultrasonic and the autoclave-treated fibers showed complete separation of cellulose fibrils, with punctures and pores on the surface. High resolution transmission electron microscope and X-ray diffraction studies suggested monoclinic unitary crystal structure. The cellulose polypropylene composite fabrications were achieved by using injection-molding technique where the composites with 25\% cellulose loading gave high tensile strength of 27 MPa, without any addition of coupling agents. Thermogravimetric analysis study showed that the thermal stability of composites was enhanced by 150 degrees C as compared to singular cellulose and polypropylene. The low water and diesel uptake suggested the compact structure of the composites. This study has developed green techniques combining heat and eco-friendly chemical treatment for cellulose extraction from agro-lignocellulosic wastes. The cellulose/polypropylene composites developed with high tensile strength, high thermal stability, and low water and diesel sorption have great potentials for conversion into eco-composite products such as polymeric material insulated cables for high voltage engineering, automotive parts, sports tools and other household or office items. (C) 2016 Elsevier Ltd. All rights reserved.
This work explored two modification methods to improve biochar's ability to sorb arsenic (As) and lead (Pb). In one, pine wood feedstock was pyrolyzed in the presence of MnCl2 center dot 4H(2)O (MPB) and in the other it was impregnated with birnessite via precipitation following pyrolysis (BPB). The resulting biochars were characterized using thermogravimetry, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy-dispersive X-ray analyses. The dominant crystalline forms of Mn oxides in the MPB and BPB were manganosite and birnessite, respectively. Batch sorption studies were carried out to determine the kinetics and magnitude of As(V) and Pb(II) onto the biochars. As(V) and Pb(II) sorption capacities of MPB (0.59 and 4.91 g/kg) and BPB (0.91 and 47.05 g/kg) were significantly higher than that of the unmodified biochar (0.20 and 2.35 g/kg). BPB showed the highest sorption enhancement because of the strong As(V) and Pb(II) affinity of its birnessite particles. (C) 2015 Elsevier Ltd. All rights reserved.
In the world, the evolution of biodiesel demand influences the global market of edible feedstocks, affecting their commercial prices and availability and consequently food security. Colombia as a tropical country has the potential of producing multiple oleochemical feedstocks including both edible and non-edible vegetable oils and animal fats. However, the oleochemical industry in the country is based on a small range of feedstocks. In this paper, five oleochemical feedstocks were selected according to comparative criteria of national availability, potential oleochemical derivatives, projected expansion, impact on food security and land requirements. This analysis allowed obtaining oil palm, maize, jatropha, castorbean, and microalgae as promissory feedstocks. Then, multiproduct biorefineries were developed and economically and environmentally assessed, according to their production features. Thus, it was stated that the proposed configurations were able to support the development of the oleochemical industry in Colombia providing sustainable alternatives, which supply a growing demand of biodiesel and other oleochemical derivatives. (C) 2013 Elsevier Ltd. All rights reserved.
The dual bamboo and coconut waste-derived catalyst was utilized to enhance the esterification reaction between two incompressible reactants, (oleic acid and methanol), to increase the mass transfer, which further decreased the reaction time and energy. The comparison study of the sulfonated dual waste biochar (DWBS) with single biomass-derived catalysts, sulfonated bamboo biochar (BBS), and sulfonated coconut husk biochar (CHBS) shows that the DWBS catalyst efficiently produces biodiesel by esterification reaction under optimum conditions. The catalyst significantly reduces activation energy to a greater extent, with a value of 32.32 kJ/mol as compared to BBS and CHBS catalysts. The reusability study reveals that the DWBS catalyst is effective for up to six cycles, demonstrating the catalyst's remarkable stability. The results indicate that the DWBS catalyst could be used for biodiesel production with low catalyst loading and a high reaction rate.
Xylo-oligosaccharides (XOS) is a kind of high-value substance with bioactivity, extracted from plants with liquid hot water (LHW) treatment that is usually applied for biorefinery. Herein, we reported a system of LHW with tiny choline chloride (ChCl) to treat a shrub Caragana korshinskii to improve XOS extraction. It is found that the ChCl acted as a buffer in LHW pretreatment promotes the XOS extraction with a yield of 36.59\% at 160 degrees C for 120 min. Compared with LHW/NaOH pretreatment, it also showed that the content of xylan in the residue was decreased by about 14\% after LHW/ChCl pretreatment. The concentrations of furfural and 5-HMF in the hydrolysate were decreased after LHW/ChCl pretreatment. Moreover, the cellulose conversion rate of the residue treated with ChCl was 41.30\% when using 25 FPU/g-substrate cellulase and 25 CBU/g-substrate beta-glucosidase, an increase of 38\% compared with the untreated one. The LHW/ChCl pretreatment provided a strategy to utilize the sandy growth biomass for high value products.
Emergence of ``severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2){''
The ability to produce second-generation itaconic acid by Aspergillus terreus, and the inhibitory effects of hydrolysis by-products on the fermentation were evaluated by cultivation in a synthetic medium containing components usually present in a real hydrolysate broth from lignocellulosic biomasses. The results showed that A. terreus NRRL 1960 can produce itaconic acid and consume xylose completely, but the conversion is less than the fermentation using only glucose. In addition, compared to fermentation of glucose, or even xylose, the mix of both sugars resulted in a lower itaconic acid yield. In the inhibitory test, the final itaconic acid titer was reduced by acetic acid, furfural, and 5-hydroxymethylfurfural concentrations of, respectively, 188, 175, and 700 mg L-1 . However, the presence of any amount of acetic acid proved to be detrimental to itaconic acid production. This research sheds some light on doubts about the biorefinery implementation of itaconic acid production.
Nanocellulose (NC) has attracted attention in recent years for the advantages offered by its unique characteristics. In this study, the effects of the preparation method on the properties of starch films were investigated by preparing NC from cationic-modified microcrystalline cellulose (MD-MCC) using three methods: Acid hydrolysis (AH), high-pressure homogenization (HH), and high-intensity ultrasonication (US). When MD-MCC was used as the starting material, the yield of NC dramatically increased compared to the NC yield obtained from unmodified MCC and the increased zeta potential improved its suspension stability in water. The NC prepared by the different methods had a range of particle sizes and exhibited needle-like structures with high aspect ratios. Fourier transform infrared (FTIR) spectra indicated that trimethyl quaternary ammonium salt groups were introduced to the cellulose backbone during etherification. AH-NC had a much lower maximum decomposition temperature (T-max) than HH-NC or US-NC. The starch/HH-NC film exhibited the best water vapor barrier properties because the HH-NC particles were well-dispersed in the starch matrix, as demonstrated by the surface morphology of the film. Our results suggest that cationic NC is a promising reinforcing agent for the development of starch-based biodegradable food-packaging materials.
The objective of this work is to study the adsorption of lead and cadmium on raw date pits. In a second phase we cross linked carboxylic functions from Diethylenetriaminepentaacetic dianhydride (DTPAD) on raw date pits in order to evaluate any improvement of the adsorption capacity of the adsorbent. We used mathematical models of Langmuir, Freundlich, Temkin and Dubin-Radushkevich to represent the adsorption isotherms and evaluate which model fits correctly the adsorption mechanism. It was observed that the adsorption capacity of raw date pits (RDP) was increased after the functionalization of RDP with DTPAD. According to Langmuir isotherm, the maximum uptake capacities (q(max)) were 15.625 mg and 59.17 mg of lead(II) per gram of RDP and modified-RDP respectively, while they were 8.55 mg and 89.3 mg of cadmium(II) per gram of RDP and modified-RDP respectively. The adsorption energy for RDP powder was 22 kJ/mol and 10 kJ/mol for Pb2+ and Cd2+ respectively, suggesting that the process of the adsorption of Pb2+ is a chemisorption while an ion exchange process is dominant in the adsorption of Cd2+. The adsorption energy was around 8.45 kJ/mol and 7.07 kJ/mol on modified-RDP powder for Pb2+ and Cd2+ respectively; inducing that an ion exchange reaction occurs for Pb2+ and a physisorption takes place for Cd2+. We performed FT-IR spectroscopy to characterize the raw and the modified powder. The analysis of the powder via scanning electronic microscopy indicates the formation of linking bridges.
In this study, ultrasound-assisted alkaline pretreatment is developed to evaluate the morphological and structural changes that occur during pretreatment of cellulose, and its effect on glucose production via enzymatic hydrolysis. The pretreated samples were characterized using scanning electron microscopy, infrared spectroscopy, and X-ray diffraction to understand the change in surface morphology, crystallinity and the fraction of cellulose I beta and cellulose II. The combined pretreatment led to a great disruption of cellulose particles along with the formation of large pores and partial fibrillation. The effects of ultrasound irradiation time (2, 4 h), NaOH concentration (1-10 wt\%), initial particle size (20-180 mu m) and initial degree of polymerization (DP) of cellulose on structural changes and glucose yields were evaluated. The alkaline ultrasonic pretreatment resulted in a significant decrease in particle size of cellulose, besides significantly reducing the treatment time and NaOH concentration required to achieve a low crystallinity of cellulose. More than 2.5 times improvement in glucose yield was observed with 10 wt\% NaOH and 4 h of sonication, compared to untreated samples. The glucose yields increased with increase in initial particle size of cellulose, while DP had no effect on glucose yields. The glucose yields exhibited an increasing tendency with increase in cellulose II fraction as a result of combined pretreatment.
Biochars prepared from anaerobic digestion residue (BC-R), palm bark (BC-PB) and eucalyptus (BC-E) were used as sorbents for removal of cationic methylene blue dye (MB). The FE-SEM images indicated that the biochars have a well-developed pore structure, and the Brunauer-Emmett-Teller surface areas of BC-R, BC-PB, and BC-E were 7.60, 2.46, and 10.35 m(2) g(-1), respectively. The efficiencies of MB removal in the samples with initial concentrations of 5 mg L-1 at pH 7.0 and 40 degrees C by BC-R, BC-PB, and BC-E after 2 h were 99.5\%, 99.3\%, and 86.1\%, respectively. Pseudo-second-order kinetics was the most suitable model for describing the adsorption of MB onto the biochars. The experimental data were best described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 9.50 mg g(-1) at 40 degrees C for BC-R. The biochars produced from the three types of solid waste showed considerable potential for adsorption. (C) 2013 Elsevier Ltd. All rights reserved.
When optimizing the process parameters of the acidic ethanolic organosolv process, the aim is usually to maximize the delignification and/or lignin purity. However, process parameters such as temperature, time, ethanol and catalyst concentration, respectively, can also be used to vary the structural properties of the obtained organosolv lignin, including the molecular weight and the ratio of aliphatic versus phenolic hydroxyl groups, among others. This review particularly focuses on these influencing factors and establishes a trend analysis between the variation of the process parameters and the effect on lignin structure. Especially when larger data sets are available, as for process temperature and time, correlations between the distribution of depolymerization and condensation reactions are found, which allow direct conclusions on the proportion of lignin's structural features, independent of the diversity of the biomass used. The newfound insights gained from this review can be used to tailor organosolv lignins isolated for a specific application.
To reveal the synergistic effect of hydrogen peroxide and ammonia on lignin, four kinds of ball-milled wood lignins, named as UN-L, HP-L, AFEX-L and H-AFEX-L respectively, were isolated from corn stover of untreated, hydrogen peroxide pretreatment alone, ammonia fiber expansion pretreatment alone and combined hydrogen peroxide and ammonia fiber expansion pretreatment. Modern analytical techniques including elemental analysis, gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectroscopy and two-dimensional heteronuclear single-quantum coherence nuclear magnetic resonance (2D-HSQC NMR) spectroscopy were applied to analyze the characteristics of the obtained lignins. The results showed that oxidation, ammonolysis were main chemical reaction during H-AFEX pretreatment. The action site of oxidation was S unit, while that of ammonolysis were ferulate and p-coumarate ester bonds. The synergistic effect of hydrogen peroxide and ammonia strengthened ammonolysis effect whereas weakened oxidation effect. Ammonia selectively degraded the ester bond, while hydrogen peroxide selectively degraded the resinol structure. The synergistic effect of hydrogen peroxide and ammonia could not only effectively degrade lignin, but also greatly reduce its PI to obtain homogeneous lignin fragments.
This work deals with the use of a supersorbent, i.e., sodium hydroxyethylcellulose succinate (HEC-Suc-Na), for the removal of Cd(II) ions from aqueous solution. HEC-Suc was fabricated via esterification of HEC with succinic anhydride in the presence of dimethylaminopyridine (DMAP) as a catalyst. The treatment of HEC-Suc conjugate with saturated NaHCO3 solution provided HEC-Suc-Na (sodic form). These acidic and sodic forms of the sorbent were characterized by Fourier transform infrared and energy-dispersive spectroscopy. The surface morphology and charge on the surface of sorbent were monitoredby SEM and pH corresponding to point of zero charge. Sorption data conceded well to the pseudo-second-order kinetic and Langmuir isotherm model. Maximum sorption capacity of HEC-Suc-Na for Cd(II) removal as calculated by Langmuir model was 714.2 mg g(-1). Moreover, no significant decrease in the sorption capacity of the sorbent was found after five regeneration cycles suggesting its repeated use. Thermodynamic parameters(Lambda G degrees, Lambda H degrees and Lambda S degrees) showed negative values that indicate spontaneity and exothermic nature of the sorption process. Removal of Cd(II) in presence of Ni(II) was also studied.
Microalgae research has attracted interest worldwide and in order to advance algal biotechnology in Brazil, government has been funding several projects. In the last 10 years, two main funds were provided by the National Council of Scientific and Technological Development (CNPq) agency to researchers in Brazil, who study the potential uses of microalgae for biomass, bioproducts and biofuels production. These funded projects addressed aspects of algal strain identification, development of algal cultivation techniques, designing photobioreactors and raceway ponds, modeling harvesting and dewatering process, maximizing biomass and oil productivities, characterizing chemical composition with different extractions systems and determining physiochemical properties of biodiesel. This review presents the state of art of algal research conducted by Brazilian institutions. Special attention is given to the recent progress on microalgal cultivation, high-value products extracted from microalgae and potential biofuels production. This review may serve as a policy instrument for planning next steps for algal research in Brazil as well as for attracting attention from international researchers who work with microalgae and would like to pursue a future partnership on algal research with Brazilian research institutions.
Heterogeneously catalyzed depolymerization of lignin to value-added chemicals is increasingly attractive but highly challengeable. Particularly, the diffusion limitation of lignin macromolecule to the solid catalyst surface is a big barrier, which significantly decreases the yield of monomer while increasing char formation. Therefore, for the potential industrial utilization of lignin, new knowledge focused on the size of lignin particles is of great importance to offer guidance for promoting lignin depolymerization and suppressing condensation in the heterogeneously catalytic systems. In this Review, the size of lignin particles and macromolecules are summarized. Previous approaches for improving the mass diffusion including enhancing the solubility of lignin and exploitation of hierarchical and ``solubilized{''
Cellulases are the enzymes of enormous industrial interests. In this study, solid-state fermentation (SSF) of alkali-pretreated orange peel waste has been evaluated to produce fungal cellulase. Different concentrations of alkali solution for the pretreatment of substrate and its impact to maximize the cellulase production have been investigated. Furthermore, process parameters of SSF including different substrate amount, different particle size of substrate, and impact of different moisture contents have been analyzed to achieve maximum cellulase production under the optimized conditions which include pretreatment using 1.0\% alkali solution, 7.0 g substrate, 2.2 mm particle size of substrate, and 65\% moisture content, wherein fungal strain Emericella variecolor NS3 exhibited the highest cellulase production of 39 IU/gds FP (filter paper cellulase), 236 IU/gds EG (endoglucanase), and 197 IU/gds BGL (beta-glucosidase). The produced raw enzyme holds improved thermal and pH stability up to 3.5 h at 65 degrees C and over pH 4.0-6.0 in the presence of 1.0\% nickel cobaltite nanoparticles (NiCo2O4 NPs). Consequently, NiCo2O4 NP-stabilized enzyme exhibited improved hydrolytic efficiency for alkali-pretreated rice husk as compared to control enzyme system. This work may be potentially applied for the mass-scale production of enzyme using orange wastes at industrial scale.
The current study investigated an integrated fermentation process for efficient conversion of pulp and paper sludge (PPS) material to bio-ethanol. To achieve maximum yield of reducing sugar from the pretreated PPS, most influencing parameters such as enzyme dosages, surfactant dosages on PPS loadings were optimized in a batch saccharification process using response surface methodology. The experimental validation studies under optimal conditions of 6\% (w/w) solid loading condition, 0.16\% (w/w) of surfactant concentration and 158 FPU/gm of enzyme loading resulted in a maximum reducing sugar yield of 45 ? 3.75\% (w/w). Separate batch saccharification studies were conducted with 4\% to 7\% (w/w) solid loading to formulate best operating conditions for fedbatch saccharification with 13\% (w/w), 18\% (w/w) and 22\% (w/w) high solid loading. The PPS solid loading of 18\% (w/w) in fed-batch saccharification resulted in maximal release of glucose and xylose of 79.56 g/L and 8.65 g/L respectively at 60 h. Further improvement in the conversion of PPS to bioethanol was established through adoption of fed-batch semi-simultaneous saccharification and co-fermentation (S-SSCF) process. Fermentation using co-cultivation of two yeast species namely P. stipitis NCIM 3499 and Baker?s yeast resulted in maximum ethanol concentration of 42.34 g/L with 0.53 g/g yield from 18\% (w/w) solid loading. Thus, the current study demonstrated the potential application of PPS waste as a feedstock material for ethanol production, which can be adopted by industries as an environment-friendly alternative to common solid waste management.
Biocomposite materials manufactured from natural fibres and polymer matrix represent a group of engineered composite products with diverse applications. These materials continue to find increasing applications due to their design flexibility, superior properties and aesthetic appeal. The applicability of these biocomposites, however, depends on the interaction in the fibre-matrix interface. This paper reviews the state of the art research in fibre-matrix interfacial interaction based on published literature. A brief background on biocomposite materials is presented. The focus of this review is the modification of natural fibres and its effect on fibre-matrix interfacial adhesion and properties. In addition, the effect of chemical treatment on fibre composition and fibre-matrix interfacial bonding mechanism are discussed.
A novel adsorbent derived from banyan aerial roots was prepared via modification and employed to aqueous gentian violet (GV) and rhodamine B (RhB) removal. The surface morphology and physicochemical properties of modified banyan aerial roots (MBARs) were investigated by SEM, EDS, N-2 adsorption/desorption, zeta potential, XRD, and FT-IR characterization experiments. Adsorption factors were tested, and the optimal conditions for GV and RhB removal were pH of 6 and 3, doses of 0.02 g and 0.03 g, and reaction time of 540 min. Adsorption isotherm simulation illustrated that theoretical monolayer adsorption capacities of GV and RhB were 456.64 mg/g and 115.23 mg/g, respectively. Kinetics data was assessed with pseudo-first-order and pseudo-second-order models, and the latter described GV and RhB adsorption better at 288 K, 298 K, 308 K, and 318 K. Thermodynamic analysis indicated that GV and RhB adsorption processes were endothermic and spontaneous. From the research results, it could be inferred that GV adsorption was mainly dominated by electrostatic interaction, while RhB adsorption might be primarily attributed to electrostatic interaction and hydrogen bonding. The study based on full utilization of waste plant fibers facilitates recycling of biomass resources, and due to simplicity, safety, and eco-friendliness of the preparation, as well as low cost and high efficiency of the application, MBARs may be potential absorbents for the treatment of dyestuff wastewater.
Lignocellulosic biomass is a rich source of cellulose and one of the most promising raw materials for the production of biofuels and other value added chemicals. However, its high lignin content and complex cellular structure represent a significant processing challenge. In this work, the effect of pretreatment using {[
Hydrodynamic cavitation (HC) is a process technology with potential for application in different areas including environmental, food processing, and biofuels production. Although HC is an undesirable phenomenon for hydraulic equipment, the net energy released during this process is enough to accelerate certain chemical reactions. The application of cavitation energy to enhance the efficiency of lignocellulosic biomass pretreatment is an interesting strategy proposed for integration in biorefineries for the production of bio-based products. Moreover, the use of an HC-assisted process was demonstrated as an attractive alternative when compared to other conventional pretreatment technologies. This is not only due to high pretreatment efficiency resulting in high enzymatic digestibility of carbohydrate fraction, but also, by its high energy efficiency, simple configuration, and construction of systems, besides the possibility of using on the large scale. This paper gives an overview regarding HC technology and its potential for application on the pretreatment of lignocellulosic biomass. The parameters affecting this process and the perspectives for future developments in this area are also presented and discussed.
The conventional application of thermal pretreatment of sewage sludge has been to apply it prior to the anaerobic digestion. In this study, the thermal treatment of the digestate was assessed at lab-scale under several temperature and time conditions. Biochemical methane potential (BMP) tests were set up to evaluate the methane production kinetic by using the Gompertz modified and the first order equation. A fullscale digester evaluation was done by using the ADM1 model under different scenarios and by using the parameters drawn from the BMP tests. The best results were obtained at 180 degrees C and 200 degrees C both at 30 min where an improvement of 50\% in the methane yield in regards to raw digestate. Full-scale simulations show that a scenario with two anaerobic reactors with thermal inter-treatment would improve the methane production by 45\% and 20\% compared to conventional anaerobic digestion and pretreatments followed by anaerobic digestion, respectively. (C) 2016 Elsevier Ltd. All rights reserved.
In the last decade, there has been increasing scrutiny of using biochar to remove pollutants from the waste water. However, due to particle size of biochar and the difficulty of its separation after the adsorption process, the use of these adsorbents has always been a challenge, until magnetic biochar (MB) was proposed by researchers. The production of MB is divided into pre-pyrolysis and post- pyrolysis methods. The MB activation/modification methods included physical and chemical activation/ammonization, sulfurization, oxidation, polymerization and MB production without modification/activation was investigated. In this research, studies that produced MB as a one-step heating and post-pyrolysis method reviewed. The results showed that the capacity of different MB to remove lead, cadmium, chromium, copper, and arsenic was calculated to be 96.9, 91.2, 90.5, 97.6 and 55.42\%, respectively. In these studies, the weight ratio of the magnetic fraction to biochar, temperature, and carbonization time were 1.2 (g/g), 575 degrees C, and 130 min, respectively. During the absorption process, the adsorption capacity of magnetic biochar increased and then reached a constant value. Therefore, the magnetic biochar has good ability to hold the adsorbed pollutants to the end of process. Also, as the initial pollutant concentration increased, the adsorption capacity unexpectedly increased and eventually reached its maximum, indicating a high affinity of the magnetic biochar with the pollutants.
Two alternative routes of softwood catalytic oxidative fractionation to cellulose products and fine chemicals are assessed. We suggested to use the process of larch wood peroxide oxidation in the medium acetic acid - water at temperatures 70-100 degrees C in the presence of soluble catalyst (NH4)(6)Mo7O24 to produce microcrystalline cellulose (35.0 wt\% on wood), microfibrillated cellulose (7.5 wt\% on wood) or nanocrystalline cellulose (3.7 wt\% on wood) and low molecular weight organic compounds (20 wt\% on wood). The developed process reduces the number of technological stages and increase an environmentally safety of nanocelluloses production from wood, compared to traditional technologies. Another suggested process of softwood (pine and larch) fractionation to vanillin (up to 4.7 wt\% on wood) and cellulose (up to 34.6 wt\% on wood) is based on wood oxidation by oxygen in water-alkaline medium at temperatures 160-180 degrees C in the presence of suspended catalyst Cu(OH)(2). The further acid conversion of cellulose by 2 \% H(2)SO(4)at 180 degrees C produces levulinic acid with the yield up to 9.7 wt \% on wood. The integration of the processes of dihydroquercetin and arabinogalactan extraction isolation from larch wood, oxidation of extracted wood by oxygen to vanillin and cellulose in the presence of catalyst Cu(OH)(2), acid catalyzed conversion of cellulose to levulinic acid and arabinogalactan hydrolysis over solid acid catalyst to arabinose and galactose leads to an increase in the number of target products. FTIR, XRD, SEM, AFM, solid state C-13 CP/MAS and chemical methods were used for characterization of cellulose products. Organic compounds were identified by GC, HPLC and GC-MS methods. The two alternative schemes of larch wood catalytic oxidative biorefinery to produce nanocelluloses and fine chemicals have been developed.
The objective of this study was to characterize the performance of composite wood blocks (CWB) by testing internal bonding, nail extraction resistance, and water absorption. The CWB were glued with two wood adhesives, polyvinyl acetate (PVAc), and urea formaldehyde (UF), modified with 1\% nanocrystalline cellulose (NCC). Three tropical species were employed: Vochysia ferruginea, Cordia alliodora, and Gmelina arborea. In addition, the original European pallet in the static flexure test was evaluated. The results showed that the internal bonding relative to solid wood blocks (SWB) increased with both adhesives. Meanwhile, the CWB of V. ferruginea with UF and C. alliodora with PVAc showed the greatest resistance to nail extraction, while in G. arborea, the NCC increased the resistance to nail extraction. The CWB with modified adhesives absorbed more moisture, particularly with PVAc, compared with the SWB. In static flexure tests of the pallets fabricated with CWB, the load at the limit of proportionality and the maximum load increased, while deflections were lower, compared with SWB. The results showed the potential of utilizing NCC in CWB fabricated with tropical species.
Recent studies on microwave processing of biomass for bioenergy production are reviewed. Statistical review of published research papers related to microwave and biomass was used to classify microwave processing used in bioenergy production. Microwaves have potential for use in various processing methods such as pretreatment, gasification, pyrolysis, transesterification, extraction, liquefaction and drying, to achieve low energy consumption, rapid reaction time, and high production yield. Microwave-assisted processing technologies for the second generation biomass (lignocellulosic biomass) and third generation biomass (algae and seaweeds) are described, as first generation biomass (food crops such as sugar canes, corns and grains) is often discussed as a ``fuel versus food{''
The aim of this Concept article is to highlight different aspects of using biomass residues or extracted molecules in the synthesis of zeolites (mainly), aluminas and layered doubled hydroxides (LDHs). The strategies presented should serve as a basis for rationally preparing those aforementioned materials for catalytic purposes. Indeed, the presence of sugars, lignin, lignocellulosic biomass usually induces morphological/textural changes as well as (in some cases) modified chemical composition and surface properties.
To elucidate the physicochemical properties and degradation mechanism of hemicellulose treated with irradiation doses (from 0 to 1200 kGy), a set of experiments on hemicellulose morphology, structure, molecular weight, free radicals, thermal stability, and irradiation mediated fractions was performed. Fourier transforms infrared spectroscopy and nuclear magnetic resonance analyses show that irradiation destroys the inter- and intra-molecular hydrogen bonds of hemicellulose leading to the generation of reductive carbonyl group. Scanning electron microscope, electron paramagnetic resonance and gel permeation chromatography measurements further confirm that the damage degree of hemicellulose structure and morphology surface in dependence on irradiation doses. Thermogravimetry/differential thermogravimetry analyses indicate that the activated energy and thermal stability of irradiated hemicellulose decrease with the increasing of absorbed dose. Irradiation mediated degradation compounds analyses by ion chromatography reveal that xylose (7.64 +/- 0.92 mg g(-1)), and arabionose (3.58 +/- 0.08 mg g(-1)) and cellubiose (0.27 +/- 0.00 mg g(-1)) are observed at 1200 kGy. Amount of glucuronic acid (3.61 +/- 0.02 mg g(-1)) and galacturonic acid (7.44 +/- 0.38 mg g(-1)), which are respectively derived from glucose and galactose, are also obtained in the water soluble irradiation mediated degradation fraction. These data provide a basis support on a full utilization of hemicellulose after gamma-irradiation pretreatment.
This work focuses on the immobilization of a crude inulinase extract obtained by solid-state fermentation using spray-drying technology. Maltodextrin and arabic gum were used as immobilizing agents. The effects of inlet air temperature, maltodextrin/arabic gum ratio and mass fraction of crude enzyme extract on the activity of immobilized inulinase were assessed using a central composite rotatable design (CCRD) (2(3)). The optimum operational conditions for the immobilization of inulinase by spray-drying was obtained at an inlet air temperature of 200 degrees C, mass fraction of crude enzyme extract of 0.5 wt\% and using only arabic gum as immobilizing agent. The immobilized enzyme had good thermostability, comparable with other inulinases obtained from different microorganisms. The method used gave good enzyme activity after immobilization and could be applied to other enzymes which have good thermal stability.
The recently discovered wild yeast Wickerhamomyces sp. UFFS-CE-3.1.2 was analyzed through a high-throughput experimental design to improve ethanol yields in synthetic media with glucose, xylose, and cellobiose as carbon sources and acetic acid, furfural, formic acid, and NaCl as fermentation inhibitors. After Plackett-Burman (PB) and central composite design (CCD), the optimized condition was used in a fermentation kinetic analysis to compare this yeast's performance with an industrial Saccharomyces cerevisiae strain (JDY-01) genetically engineered to achieve a higher xylose fermentation capacity and fermentation inhibitors tolerance by overexpressing the genes XYL1, XYL2, XKS1, and TAL1. Our results show that furfural and NaCl had no significant effect on sugar consumption by UFFS-CE-3.1.2. Surprisingly, acetic acid negatively affected glucose but not xylose and cellobiose consumption. In contrast, the pH positively affected all the analyzed responses, indicating a cell's preference for alkaline environments. In the CCD, sugar concentration negatively affected the yields of ethanol, xylitol, and cellular biomass. Therefore, fermentation kinetics were carried out with the average concentrations of sugars and fermentation inhibitors and the highest tested pH value (8.0). Although UFFS-CE-3.1.2 fermented glucose efficiently, xylose and cellobiose were mainly used for cellular growth. Interestingly, the genetically engineered strain JDY-01 consumed similar to 30\% more xylose and produced similar to 20\% more ethanol. Also, while UFFS-CE-3.1.2 only consumed 32\% of the acetic acid of the medium, JDY-01 consumed > 60\% of it, reducing its toxic effects. Thus, the overexpressed genes played an essential role in the inhibitors' tolerance, and the applied engineering strategy may help improve 2G ethanol production.
The demand for exploring eco-friendly and advanced materials for sustainable development with exceptional physicochemical properties is increasing day by day. Recently, nanocellulose in its all form such as cellulose nanocrystal, cellulose nanofibers, and bacterial cellulose gain great attention in both research and industrial areas due to their appealing inherent properties such as excellent mechanical properties, high concentration of hydroxyl groups for modification, high surface area, lightweight, and biodegradability. However, the hydrophilic nature of nanocellulose restricted its utilization in various applications, but the presence of a functional group on its surface provides a platform for surface modification through various techniques. In this review, the source of nanocellulose, a brief description of the chemical structure of nanocellulose, its type, typical production methods, surface modification, and general application such as textile, biomedical fields, wastewater purification, food packaging are summarized. It is expected to provide broad knowledge about the usefulness of present and future perspectives of nanocellulose for the benefit of the environment and society.
The study explores the potential of the Croton macrostachyus seed, a non-edible feedstock found in abundance in the southeastern parts of Ethiopia, for the production of biodiesel. Soxhlet extractor was used to extract, 53.34\% of the oil from the Croton macrostachyus seed. This oil was further purified and the resulting product was known as the purified Croton macrostachyus seed (P-CMS) oil. After obtaining the P-CMS oil, biodiesel was produced by the transesterification process. Focus was made on the optimization of biodiesel production by varying the identified process parameters, through the Box- Behnken Design using response surface methodology (RSM) (Design-Expert (R) Version 11 software). The crude biodiesel was purified, characterized and complied with the ASTM D6751, United States and the EN 14214, European Union standards. The optimum conversion efficiency of the P-CMS oil to fatty acid methyl ether (FAME) was 96\% at the optimal conditions (6:1, methanol to oil ratio; 1\%, catalyst loading; 50 degrees C, reaction temperature). A plan for the environmental impact assessment and life cycle assessment were provided to evaluate the sustainability of this new feedstock and the biodiesel produced from it. Results of these studies indicated the prospective of Croton macrostachyus seed as a new biodiesel feedstock. (C) 2020 Elsevier Ltd. All rights reserved.
Low-cost and high-efficiency catalysts are vital to the conversion of solid wastes into biofuels or chemicals. In this study, a bifunctional activated carbon catalyst modified with Fe (Fe/AC) was obtained and applied to the catalytic co-pyrolysis of Douglas fir (DF) and low-density polyethylene (LDPE) using a facile fixed bed reactor. The effects of Fe loading amount, catalyst to feedstock ratio, and pyrolysis temperature on the product yields and distributions were studied. Results showed that the highest yield of bio-oil (53.67\%) was achieved using 10Fe/AC at a pyrolysis temperature of 500 degrees C with a catalyst to feedstock ratio of 1. The main chemical compositions of the obtained catalytic bio-oil were aromatics, alkanes, and phenols. Increasing the temperature (450-600 degrees C) and catalyst to feedstock ratio (0.5-2) enhanced the selectivity of aromatics at the expense of phenols and alkanes. Compared to the AC catalyst, Fe/AC exhibited excellent performance on aromatics production (especially mono-aromatics) due to the newly created acid sites. The catalytic synergistic effect over 10Fe/AC significantly promoted the formation of aromatics through hydrogen transfer reactions which facilitated the dehydroxylation and demethoxylation of phenols. The present work provides a promising approach of converting biomass and plastic wastes directly into jet fuel range hydrocarbons by using green inexpensive carbon-based catalysts.
Digestate from biowaste was assessed as a potential source of bioproducts of commercial and industrial interest through solid-state fermentation. The targeted bioproducts were hydrolytic enzymes (cellulases and proteases from autochthonous microbiome), biosurfactants (sophorolipids produced from Starmella bombicola) and bio-pesticides (produced from Bacillus thuringiensis). Low cellulase production was observed within the range of 0.5-1.5 FPU g(-1) DM while protease production showed two discrete peaks of 66 +/- 8 and 65 +/- 3 U g(-1) DM at 3.5 and 48 h, respectively. Low sophorolipids production was also obtained, with a maximum yield of 0.02 g g(-1) DM using hygienised digestate supplemented with external sugar and fat sources. Biopesticides produced by B. thuringiensis were successfully at 72 h of operation, reaching a maximum spore production of 8.15 +/- 0.04 (107) CFU g(-1) DM and 2.85 +/- 0.22 (107) CFU g(-1) DM using sterile and hygienised digestate, respectively. These biopesticides could contribute to the substitution of chemically produced pesticides, moving towards a sustainable digestate management in a circular economy scheme.
Thermal pretreatment of biomass is crucial for its efficient utilization. Two types of common biomass were selected for integrated water washing and carbonization pretreatment, specifically water washing-torrefaction (WT) and hydrothermal carbonization (HTC), respectively. The fuel properties, combustion characteristics, and representative ash-related pollutant PlVfi o (particulate matter with aerodynamic diameter of 10 mu m or less) emission performance were evaluated. The results indicated that both the WT and HTC had beneficial effects in improving the fuel properties and combustion characteristics, and also alleviated severe ash-related problems of biomass. Then the modeling of mass and energy balance under auto-thermal conditions was established based on the experimental data. Subsequently, economic evaluations were performed at three plant capacities. The net present value (NPV) increased with upscaling, with the production of pine biochar (WTP) at 1000 kg/h capacity having the highest NPV value of 7.76 M(sic) and lowest cost of production (COP) value of 9.1 (sic)/GJ. The NPV was most dependent on the biochar/hydrochar price, whereas the variations in electricity price, working hours of the plant, and number of workers together dominated the COP. Furthermore, the effect of carbon tax illustrated that WT was more affected than HTC; the COP was approximately zero under the carbon-neutral scenario.
Bacterial cellulose nanocrystals (BCNCs) have hydrophilic surfaces due to hydroxyl groups but are water-insoluble. The carboxymethylation improves the solubility of cellulose in polar media through the insertion of carboxymethyl groups. This study aims to evaluate the use of two different alcoholic solvents in the carboxymethylation reaction of BCNCs: ethanol and isopropanol. BCNCs were obtained under two hydrolysis conditions: sulfuric acid (BCNC-S) and combination of sulfuric and hydrochloric acids (BCNC-S/Cl). Two techniques (NMR and titration) were used to determine the degree of substitution (DS) values. Carboxymethylation of BCNC-S/Cl led to high DS compared to BCNC-S and the use of isopropanol promoted an even greater DS. The thermal properties were not affected after the chemical modification. However, functionalization provided an increase in the negative charge density at the surface of nanostructures and a change in the crystal structure (cellulose type I for amorphous), making this material a potential polyanion for the synthesis of polyelectrolyte complexes (PECs). The micrographs showed that the nanocrystals became soluble after carboxymethylation. Carboxymethylated bacterial cellulose nanocrystals hydrolyzed through the mixture of inorganic acids and modified using isopropanol (CBCNC-S/Cl-IPA) was a suitable polyanion to produce PECs with chitosan. The PECs produced had particle size ranging from 276 to 588nm and zeta potential ranging from -24.3 to +39.0mV. {[
Mixing constitutes a critical design parameter in solid-state fermentation (SSF) bioreactor and its effect on heat and water transport, and microbial growth in substrate bed can significantly influence overall productivity. Effect of mixing events on the production of a thermo-tolerant and acid stable phytase, by Rhizopus oryzae, was studied in a novel SSF bioreactor, using optimized growth medium containing wheat bran and linseed oil cake (1:1) as main substrate. A critical mixing phase was identified, in the absence of which fungal growth led to the onset of heat accumulation and subsequent bed drying. The tensile strength of hyphal bonds between two substrate particles, at this critical phase, was estimated and related to the mixing intensity in the bioreactor that resulted in an optimum working value of 15 rpm. Effect of mixing time on bioreactor performance was also investigated where a 3 min mixing duration, at every 6 h, increased biomass and phytase productivity to 2.2- and 4.5-fold, respectively, in comparison to packed bed bioreactor (PBR). The proposed bioreactor system with intermittent mixing gave superior performance than PBR and tray bioreactor, in terms of maximum bed temperature, axial bed temperature and biomass gradient, average bed moisture content, biomass and phytase productivity.
Among main ways to provide an environmentally friendly energy and platform chemicals are the lignocellulosic conversion processes. The proper execution of this way will depend on the correct selection of lignocellulosic materials. A compelling plant is Leucaena leucocephala because its great variety of uses, its high biomass production and its leguminous nature. In this study, acid hydrolysis (130-170 degrees C and 0.5-2\% H2SO4, to extract valuable hemicelluloses) as pretreatment and pyrolysis of the solid residue (to get a gaseous fuel) as treatment have been used in its valorization. A laboratory-scale reactor was used for the pyrolysis experiments (550 degrees C, N-2) for both Leucaena leucocephala, as raw material, and the solid residues after hydrolysis process and raw material. The amounts of CO, CO2 and H-2 found in the raw material are similar to those found in the solids obtained after the different studied hydrolysis conditions. Moreover, the thermal behavior of studied solids has been studied by thermogravimetric analysis under nitrogen atmosphere at different heating rates (5, 10, 15 and 20 degrees C min(-1)). Activation energy for all samples has been obtained by the Flynn-Wall-Ozawa method. The optimum value, in which a high relationship between recoverable hemicelluloses fraction and H-2 concentration is found, under medium hydrolysis temperature (150 degrees C) has been obtained and was independent of the amount of acid added to the hydrolysis process. (C) 2017 Elsevier Ltd. All rights reserved.
Biofuel potential of a widely grown perennial grass, Pennisetum polystachion, was analyzed using triethy-lammonium hydrogen sulfate ({[
This study investigate the thermal decomposition behavior of pine needles (PN), styrofoam (SF) as well as their mixture at ratio of 1:1 (w/w), determine the kinetic and thermodynamic parameters for co-pyrolysis of PN and SF using thermogravimetric analysis (TGA) data. The co-pyrolysis experiments were performed in an inert environment (N-2) at three variable heating rates of 5,10 and 20 degrees C/min in TG analyzer from 35 to 850 degrees C. TGA outcomes represent that the thermal degradation of PN occurred in three stages, while SF degradation took place in a single stage and degradation of their mixture occurred in three stages. Model-free methods such as Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) were employed to findout the activation energy (E-a) for co-pyrolysis of PN and SF. Moreover, the thermodynamic parameters (changes in enthalpy, Gibbs free energy and entropy) were also determined by OFW method. The pre-exponential factors were also evaluated by model-fitting (Coats-Redfern) method. The average of E-a for co-pyrolysis of PN and SF determined by KAS and OFW methods was 96.44 and 109.73 kJ/mol, respectively. The results of this study suggest that PN and SF mixture has potential to be used as a pyrolysis feedstocks. (C) 2020 Elsevier Ltd. All rights reserved.
The ethanol yields from lignocellulo-starch biomass (peels of sweet potato, elephant foot yam, tannia, greater yam and beet root) by fed-batch separate hydrolysis and fermentation (F-SHF) and simultaneous saccharification and fermentation (F-SSF) using Saccharomyces cerevisiae were compared. Fed-batch saccharification of steam or dilute sulphuric acid pretreated biomass enhanced the reducing sugar yield which resulted in high RS consumption, volumetric ethanol productivity and ethanol yield during the first 24 h fermentation under F-SHF mode, while continuous production and utilization of reducing sugars occurred up to 72 h in F-S SF. Dilute sulphuric acid pretreated residues under F-SHF gave higher ethanol yield (34-43 g/L) and productivity (274-346 ml/kg dry biomass) than steam pretreatment (27-36 g/L and 223-295 ml/kg respectively), while F-SSF was superior for steam pretreated peels of sweet potato, elephant foot yam and tannia giving ethanol yields from 281 to 302 ml/kg. Glucose and xylose were present in all the hydrolysates with a preponderance of glucose and fermentation resulted in significant reduction in glucose levels in both F-SHF and F-SSF. Higher levels of total soluble phenolics and hydroxymethyl furfural were observed in the hydrolysates from dilute sulphuric acid pretreatment and yeast assimilated/detoxified part of the inhibitors, while only trivial amounts of furfural were present due to the low xylose content in the hydrolysates. Continuous formation led to higher accumulation of inhibitors in F-SSF despite supplementation with the detoxification mix comprising Tween 20, polyethylene glycol and sodium borohydride. F-SHF of dilute sulphuric acid pretreated biomass could be considered as a comparatively advantageous process where only one time feeding of enzyme cocktail and yeast was adopted compared to multiple feeds of enzymes and yeast along with other additives such as detoxification mix or nutrient solution in F-SSF.
In this work, chitosan-modified biochars were synthesized in efforts to produce a low-cost adsorbent for heavy metal environmental remediation. Characterization results showed that the coating of chitosan on biochar surfaces could improve its performance as a soil amendment or an adsorbent. Batch sorption experiments showed that, compared to the unmodified biochars, almost all the chitosan-modified biochars showed enhanced removal of three metals (i.e., Pb2+, Cu2+, and Cd2+) from solution. Further investigations of lead sorption on chitosan-modified bamboo biochar (i.e., BB-C) indicated that, although sorption kinetics were slow, BB-C had a relatively high Langmuir lead sorption capacity of 14.3 mg/g biochar (71.5 mg/g chitosan). Sorption of lead on the chitosan-modified biochar greatly reduced its metal toxicity. Both seed germination rate and seedling growth of the Pb-laden BB-C were similar to that of control groups without lead. In addition, uptake of lead by plants was reduced about 60\% when lead was sorbed onto the chitosan-modified biochar. This work suggests that chitosan-modified biochars may be used as an effective, low-cost, and environmental-friendly adsorbent to remediate heavy metal contamination in the environment. (C) 2013 Elsevier B.V. All rights reserved.
Global environmental awareness has encouraged further research towards biofuel production and consumption. Despite the favorable properties of biofuels, the sustainability of their conventional production pathways from agricultural feedstocks has been questioned. Therefore, the use of non-food feedstocks as a promising approach to ensure sustainable biofuel production is encouraged. However, the use of synthetic solvents/chemicals and energy carriers during biofuel production and the consequent adverse environmental effects are still challenging. On the other hand, biofuel production is also associated with generating large volumes of waste and wastewater. Accordingly, the circular bioeconomy as an innovative approach to ensure complete valorization of feedstocks and generated waste streams under the biorefinery scheme is proposed. In line with that, the current study aims to assess the environmental sustainability of bioethanol production in a safflower-based biorefinery using the life cycle assessment framework. Based on the obtained results, safflower production and its processing into 1 MJ bioethanol under the safflower-based biorefinery led to damage of 2.23E-07 disability-adjusted life years (DALY), 2.35E-02 potentially disappeared fraction (PDF){*
Spillage of fossil-based oils during their conveyance through water conduits are sporadic, but significant environmental disasters. As the viscous hydrocarbons of the crude oils spread on water surface and choke aquatic life to death, their effective degradation is crucial for ecological balance. Though chemical and mechanical means are conventional ways to tackle the issues, they are riddled with limitations. In this scenario, coercing the biosurfactant-producing bacteria and fungi are promising avenues. Biosurfactants, the amphiphilic compounds, are capable of reducing interfacial tension, dispersing the oil particles, and degrading theminto non-toxic debris. Among the vast array of biosurfactants, the trio of rhamnolipid, sophorolipid, and surfactin have been characterized well. Among the microbes, only Pseudomonas, Bacillus, and Candida have been evaluated, while there can be other exploitable candidates. In this regard, this review discusses the scopes and hurdles in utilization of the microbial surface-active compounds for oil spill management.
Contents of hydroxycinnamic and hydroxybenzoic acids were determined in trimming vine shoots after sequential treatments of prehydrolysis and alkaline hydrolysis. These treatments allow the complete use of the main fractions involved: cellulose, hemicelluloses and lignin. The alkaline hydrolysis was studied using a factorial design where reaction time (in the range 30-120 min), temperature (50-130 degrees C), and NaOH concentration (4-12 wt \% of solution) were the independent variables. The interrelationship between dependent and operational variables was well fitted (R-2 > 0.90) to models including linear, interaction and quadratic terms. Ferulic acid was the most abundant hydroxycinnamate with concentrations ranging from 25.7 to 141.0 mg/L followed by p-coumaric acid (15.5-31.5 mg/L). Gallic acid was the hydroxybenzoic acid released in higher concentration (in the range 2.5-164.6 mg/L). Because of their properties and low toxicity, these compounds are widely used in the food, pharmaceutical and cosmetic industries. Additionally, ferulic acid is used as feedstock for the biotechnological production of flavorings and aroma compounds, including vanillin and vinylguaiacol, or as a constituent in the preparation of foods and skin protection agents, or as a cross-linking agent for the elaboration of food gels. Consequently, ferulic acid solutions can be obtained from renewable plant cell wall materials as a prospective pathway.
Y Recently, the bio-transformation of organic wastes to value-added products has gained huge interest due to problems related to waste disposal and fossil fuel depletion. Gaseous fuels such as biohydrogen and biomethane generation from biomass has been researched extensively and is well developed. Currently, biohythane, a gaseous mixure of biohydrogen and biomethane, with hydrogen composition of approximately 10-30\% is gaining more attention due to its superior characteristics over other biofuels. The co-production of hydrogen and methane in two-stage process improves the total energy recovery up to 100\% and 30\% respectively compared to single-stage process. The optimal conditions for biohythane production are pH 5.5-6.5, 37 degrees C for 1-3 d during first stage, and pH 7-7.5, 37 degrees C for 10(-15) d during second stage. Hythane with 10\% and 20\% (v v(-1)) hydrogen has achieved reduced NOx emission of 45\% and 50\% respectively in comparison with the methane fueled vehicles, whereas hythane with 30\% (v v(-1)) hydrogen has achieved reduced CO2 emission of 69 g km(-1). Although biohythane technology has high value as a vehicular fuel, its potential applications are yet to be explored. Enhanced biohythane quality and production rate can be obtained by selecting the most feasible substrates, controlling the microbial growth, using metabolically engineered strains and optimizing the bioreactor design. This review comprehensively discusses the mechanism of biohythane production; and its enhancement strategies such as pretreatment, co-digestion, optimization of physicochemical parameters and process integration to improvise the biohythane productivity. Finally, the techno-economic aspect for large scale biohythane production has also been addressed. In specific, this article discusses the latest achievements, their constraints and future prospects for lucrative biohythane generation.
The combination of hydrothermal pretreatment followed by delignification with imidazole was evaluated for the first time as a potential selective two-stage fractionation for elephant grass, aiming at obtaining pure fractions susceptible to conversion to high value-added products. In addition, the recovery of cellulose and hemicelluloses and enzymatic hydrolysis yield of pretreated elephant grass were evaluated. Hydrothermal pretreatment at 180 degrees C under non-isothermal conditions allowed obtaining a liquor rich mainly in xylo- and glucooligo-saccharides, as well as pentoses. Subsequent treatment of the recovered solid fraction with imidazole at 140 degrees C for 182.5 min resulted in 83.8 wt\% delignification and cellulose enrichment of 97.7 wt\%. The solids obtained from the two-stage pretreatment process also permitted high glucan to glucose conversion through enzymatic hydrolysis using Cellic CTec2 (99.0 mol\%) or an enzymatic complex of Penicillium echinulatum (96.3 mol\%).
Palm oil production generates oil palm mesocarp fiber (OPMF) as the main lignocellulosic waste from the oil/fruit separation process. The plentiful OPMF can be used for diverse applications, such as reinforcement in polymeric matrix composites or to produce glucose for second-generation ethanol. In both applications, surface properties are essential, and the presence of silica bodies is usually harmful. In the present study, three treatments to remove silica bodies were evaluated as follows: hydrothermal (HT), alkali (AT), and sodium citrate solution (ST). Morphological and structural characteristics of untreated and treated fibers were determined using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Many silica bodies attached to the untreated OPMF surface were observed. The treatments partially removed the silica bodies from the surface. AT was superior, with a removal rate of approximately 91\% as quantified by microwave-induced plasma optical emission spectrometry. The crystallinity index increased from 27\% in the raw fiber to 40\% after all treatments because of the removal of non-crystalline regions of cellulose and extracted material. Thermogravimetric analysis revealed no significant differences in the thermal stability of untreated and treated fibers. Elongation at break was the lowest for AT and HT, and the highest for ST. Removing silica bodies from the OPMF surface can benefit applications where surface properties are critical, adding value to the waste. As far as it is known, the approach used in this study is unprecedented.
Two novel absorbents were synthesized for the first time by banana and pomegranate peels using diethylenetriaminepentaacetic acid (DTPA) modification to eliminate Cd(II) and Ni(II) of sewage. The DTPA-modified peels performed significantly higher adsorption capacity than unmodified materials. The maximum adsorption capacities of DTPA-modified banana/pomegranate peel were 46.729/46.296 mg/g for Cd(II), and 29.240/16.611 mg/g for Ni(II). Adsorption isotherm and kinetics models were simulated to determine their removal efficiency and potential for recovery of these two heavy metals. As the results, the adsorption reached equilibrium within 5 min and was well described by the pseudo-second order model and Langmuir isotherm. The surface morphology analysis of the synthetic materials by Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy, Fourier Transform Infrared spectroscopy, and X-ray Photoelectron Spectroscopy, implied that ion exchange, complexation, and physical adsorption may together contribute to Cd(II) and Ni(II) loading on DTPA-modified peels. This study demonstrates the feasibility of waste peels as cost-efficient bio-absorbents to remove Cd(II) and Ni(II) in sewage systems, and discovers potential adsorption mechanism of efficiency improvements after DTPA modification.
Sulfonated carbon-based solid acid catalyst (AC-SO3H) was prepared by the sulfhydrylation and sulfonation of activated carbon (AC) with 3-thiol-propyl trimethoxy silane and sulfuric acid successively. The prepared solid acid catalyst was characterized by infrared spectroscopy (IR), thermogravimetric analysis (TGA), elemental analysis (EA), X-ray powder diffraction (XRD), and Brunauer-Emmet-Teller (BET) specific surface area analysis, and the acid density of AC-SO3H was determined by neutralization titration. AC-SO3H was then employed to catalyze the synthesis of 5-hydroxymethylfurfural (5-HMF) via the dehydration of fructose. The influence of the type of support, sulfonating agent and their concentration, catalyst amount, reaction temperature, and time was investigated. It was found that fructose was converted into 5-HMF with excellent selectivity and stability. The yield of 5-HMF reached up to 100\% under the optimized conditions. The solid acid catalyst was reused without noticeable deactivation. The yield of 5-HMF was still up to 94.3\% after 4 cycles.
This study aims to investigate the influence and interaction of experimental parameters on the production of optimum H-2 and other gases (CO, CO2, and CH4) from gasification of municipal solid waste (MSW). Response surface method in assistance with the central composite design was employed to design the fifteen experiments to find the effect of three independent variables (i.e., temperature, equivalence ratio and residence time) on the yields of gases, char and tar. The optimum H-2 production of 41.36 mol \% (15.963 mol kg-MSW-1) was achieved at the conditions of 757.65 degrees C, 0.241, and 22.26 min for temperature, ER, and residence time respectively. In terms of syngas properties, the lower heating value and molar ratio (H-2/CO) ranged between 9.33 and 12.48 MJ/Nm(3) and 0.45-0.93. The predicted model of statistical analysis indicated a good fit with experimental data. The gasification of MSW utilizing air as a gasifying agent was found to be an effective approach to recover the qualitative and quantitate products (H-2 and total gas yield) from the MSW. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Ethylenediaminetetraacetic acid modified attapulgite (EDTA-ATP) was developed as a novel and promising adsorbent for removal of aqueous Cr(III). The structure and surface properties of EDTA-ATP were characterized and the results indicated that EDTA moieties have been successfully anchored on the surface of ATP. Adsorption of Cr(III) on EDTA-ATP and aminopropyl-modified attapulgite (APTES-ATP) monotonously reduced with decreasing pH, and Cr(III) adsorption on EDTA-ATP is substantially higher than APTES-ATP in tested pH range, especially at lower pH. Presence of citric acid and gelatin had no obvious influence on Cr(III) adsorption to EDTA-ATP, but significantly reduced Cr(III) adsorption on APTES-ATP. Coexisting cations resulted in decreased Cr(III) adsorption on EDTA-ATP by competitionwith Cr(III) for surface-bound EDTA groups of the adsorbent. Adsorption isotherm of Cr(III) on EDTA-ATP followed the Langmuir model and the maximum adsorption capacity of the adsorbent for Cr(III) was 131.37 mg/g at 25 degrees C and pH 3.0. Cr(III) loaded adsorbent could be regenerated easily in HCl solution and the regenerated adsorbent still exhibited high adsorption capacity for Cr(III). XPS analysis confirmed that the enhanced Cr(III) adsorption on EDTA-ATP was ascribed to form the stable complexes between Cr (III) and surface-bound carboxyl and amino groups of the adsorbents. (C) 2020 Elsevier B.V. All rights reserved.
Pomegranate peels (PGP) were tested as a green adsorbent for the removal of Ni(II) from contaminated water samples. Both raw (RPG), and char/burnt peels (BPG) were tested. A multivariate analysis approach, Box-Behnken (BB) design was executed to augment the efficiency of BPG as adsorbent. Three factors were considered thereof; contact time (CT), adsorbent dose (AD), and heavy metal concentration (HMC). The percentage of heavy metal removal was the designated response (Y). Main effects plot together with analysis of variance (ANOVA) were used to decide on the substantial factors. Obtained results showed that AD was the most significant linear factor, while the interaction between AD{*
In this work, olive tree biomass (OTB) was pretreated with sulfuric acid at previously optimized conditions according two different criteria optimization. Then, two schemes of saccharification and fermentation were tested to evaluate the potential of bioethanol production from olive tree biomass pretreated under both optimal conditions. The best results of ethanol production were achieved from OTB pretreated at 15\% solids, 164 degrees C and 0.89\% H2SO4. However, when OTB was pretreated at 35\% solids, 160 degrees C, and 1.72\% H2SO4, more concentrated sugar solutions were obtained but the ethanologenic microorganism was not capable of assimilating all sugars in the medium. Therefore, the highest ethanol yield, 0.45 g ethanol/g sugar (88\% of the theoretical ethanol yield), corresponding to 14.4 g ethanol/100 g raw OTB was achieved when OTB was pretreated at 15\% solids using a new bioconversion scheme for this feedstock. It consisted of the enzymatic hydrolysis of the whole slurry from the pretreatment followed by the co-fermentation of cellulosic and hemicellulosic sugars by a recombinant ethanologenic Escherichia coli MM160. (C) 2018 Elsevier B.V. All rights reserved.
Biomass is abundant, renewable and useful for biofuel production as well as chemical priming for plastics and composites. Deconstruction of biomass by enzymes is perceived as recalcitrant while an inclusive breakdown mechanism remains to be discovered. Fungi such as Myceliophthora thermophila M77 appear to decompose natural biomass sources quite well. This work reports on this fungus fermentation property while producing cellulolytic enzymes using natural biomass substrates. Little hydrolytic activity was detected, insufficient to explain the large amount of biomass depleted in the process. Furthermore, this work makes a comprehensive account of extracellular proteins and describes how secretomes redirect their qualitative protein content based on the nature and chemistry of the nutritional source. Fungus grown on purified cellulose or on natural biomass produced secretomes constituted by: cellobiohydrolases, cellobiose dehydrogenase, beta-1,3 glucanase, beta-glucosidases, aldose epimerase, glyoxal oxidase, GH74 xyloglucanase, galactosidase, aldolactonase and polysaccharide monooxygenases. Fungus grown on a mixture of purified hemicellulose fractions ( xylans, arabinans and arabinoxylans) produced many enzymes, some of which are listed here: xylosidase, mixed beta-1,3( 4) glucanase, beta-1,3 glucanases, beta-glucosidases, beta-mannosidase, beta-glucosidases, galactosidase, chitinases, polysaccharide lyase, endo beta-1,6 galactanase and aldose epimerase. Secretomes produced on natural biomass displayed a comprehensive set of enzymes involved in hydrolysis and oxidation of cellulose, hemicellulose-pectin and lignin. The participation of oxidation reactions coupled to lignin decomposition in the breakdown of natural biomass may explain the discrepancy observed for cellulose decomposition in relation to natural biomass fermentation experiments.
The increasing use of synthetic polymers and their disposal has raised concern due to their adverse effects on the environment. Thus, other sustainable alternatives to synthetic plastics have been sought, such as polyhydroxyalkanoates (PHAs), which are promising microbial polyesters, mainly due to their compostable nature, biocompatibility, thermostability, and resilience, making this biopolymer acceptable in several applications in the global market. The large-scale production of PHAs by microorganisms is still limited by the high cost of production compared to conventional plastics. This review reports some strategies mentioned in the literature aimed at production and recovery, paving the way for the bio-based economy. For this, some aspects of PHAs are addressed, such as synthesis, production systems, process control using by-products from industries, and advances and challenges in the downstream. The bioplastics properties made them a prime candidate for food, pharmaceutical, and chemical industrial applications. With this paper, it is possible to see that biodegradable polymers are promising materials, mainly for reducing the pollution produced by polymers derived from petroleum.
In this work, machine learning (ML) applications in lignocellulosic bioethanol production were reviewed. First, the pretreatment-hydrolysis-fermentation route, the most commonly studied alternative, was summarized. Next, a bibliometric analysis was performed to identify the current trends in the field; it was found that ML applications in the field are not only increasing but also expanding their relative share in publications, with bioethanol seeming to be the most frequently researched topic while biochar and biogas are also receiving increased attention in recent years. Then, the implementation of ML for lignocellulosic bioethanol production via this route was reviewed in depth. It was observed that artificial neural network (ANN) is the most commonly used algorithm (appeared in almost 90\% of articles), followed by response surface methodology (RSM) (in about 25\% of articles) and random forest (RF) (in about 10\% of articles). Bioethanol concentration is the most common output variable in the fermentation step, while fermentable sugar and glucose concentration are studied most in hydrolysis. The datasets are usually small, while the fitnesses of the models (R-2) are usually high in the papers reviewed. Finally, a perspective for future studies, mostly considering improving data availability, was provided. (c) 2023 BRTeam. All rights reserved.
In this study, residues of passion fruit skin were examined as biosorbent materials, evaluating their capacity to adsorb lead(II) ions in in natura skin (SK-N) and two modified skins, with NaOH (SK-S) and with NaOH and citric acid (SK-SCA). The biomass characterization was done through Fourier transform infrared spectroscopy which confirmed the chemical modification by a peak at 1,730 cm(-1). Also, scanning electron microscopy analyses were done, where the increase of residue roughness was observed after the modification. And finally, the values of point of zero charge were determined and were lower than 5.5 for all residues. In the experiments of adsorption in function of pH, it was verified that after pH4, the adsorbed amount was practically constant. Regarding the necessary time to reach equilibrium, the value that was found was approximately 170 min, and kinetics followed the behavior described by the pseudo-second-order equation. The maximum adsorption capacity was 204 mgg(-1) for the SK-SCA biomass. The residues followed Langmuir adsorption model. Through thermodynamic parameters, it was verified that adsorption occurs spontaneously due to the negative values of Gibbs' energy. Moreover, desorption studies showed that adsorbed ions may be recovered in two cycles. Thus, due to the high adsorption capacity of lead ions, passion fruit skin can be utilized in filters to retain this metal in the future.
The interest in microbial lipids has recently increased because of their wide use to produce several value-added compounds in the biofuel, pharmaceutical and food industries. Oleaginous yeast such as Rhodosporidium tor-uloides could be an efficient option because of its ability to consume five-carbon sugars, high lipid accumulation, and tolerance to toxic compounds such as furans, phenolic compounds, and organic acids. The present study aims to investigate the effect of different initial sugar ratios, in combination with different carbon/nitrogen ratios, and the use of dibasic sodium phosphate (Na2HPO4) as an inducer on cell biomass production, sugar consumption, and lipid accumulation by Rhodosporidium toruloides-1588. The investigation showed a maximum lipid accu-mulation of 5.35 gL-1 (0.28 g of lipids/g of sugar) under the culture conditions of initial glucose: xylose ratio of 1:1, C/N ratio of 70, and Na2HPO4 concentration of 1.05 gL-1. The predominant lipids composition was palmitic, stearic, oleic, and linoleic acids which could be used as a suitable feedstock for biofuel production. Additionally, under the optimal conditions (initial glucose: xylose ratio of 1:1, 1.19 gL-1 of Na2HPO4 and C/N ratio of 70.50) an increase of 10.5\% and 7.5\% in lipid accumulation was observed, compared with control treatments (glucose and xylose, respectively). In addition, the study shows the ability of R. toruloides-1588 to tolerate inhibitors, a feature that could be a promising alternative to increase the feasibility of the microbial lipid production process using undetoxified wood hydrolysate as a sustainable culture media.
Commercial birch xylan (CX) and alkali-soluble birch xylan (ASX) were subjected to controlled acetylation and used for film formation in the presence (20\% and 40\%) or absence of plasticizers (i.e. glycerol, sorbitol and xylitol). Although the content of Klason lignin was similar (1.2-1.4\%), the acetylation process was favored by the high-purity CX (97\% xylan) over the ASX (89\% xylan). On the other hand, the presence of residual pectin heteropolysaccharides rather than xylan in the ASX sample was beneficial for film formation. These heteropolysaccharides seemed to act as natural plasticizers during film formation, allowing the formation of coherent films from ASX, even in the absence of an external plasticizer. The use of plasticizers favored the mechanical properties of films, especially in a dosage of 40\%, when plastic behavior was created. Acetylation favored the film formation and slightly improved the mechanical properties of the films, and this improvement was in the same range as that achieved when using 20\% plasticizer in non-acetylated ASX.
Reuse of concrete waste in novel construction is becoming very important topic nowadays. This study focuses to examine the post-cracking and mechanical performance, fracture behavior, and micro-structure of fiber strengthened recycled aggregate concrete (RAC). For this purpose, crack mouth opening diameter (CMOD) tests were conducted on twenty-seven notched beam specimens (550 x 150 x 150 mm) having three replacement levels (i.e., 0, 50 and 100\%) of recycled concrete aggregates (RCA) and three synthetic fiber dosages (i.e., 0, 0.5 and 1\%). Different mechanical properties of all mixes were also examined following ASTM standards. Drop in the mechanical performance of RAC was noticed at higher RCA replacement levels. However, synthetic fiber reinforced RAC showed better performance as compared to plain RAC. Results also depict positive influence of synthetic fiber addition on the residual flexural tensile strength of concrete. Approximately, 129\% and 380\% rise in toughness index and fracture energy was also observed for 1\% fiber incorporation in RAC. Moreover, scanning electron microscopic analysis also confirmed the synthetic fiber-mortar bond. Therefore, synthetic fibers enhance the post-cracking and mechanical performance of fiber reinforced RAC resulting into more ductile and energy absorbing sustainable concrete.
Over the past few decades, the fired clay brick industry has searched for industrial wastes to substitute raw clay deposits and lessen their impact on the environment. Despite several investigations showing positive results, industrial applicability is still scarce, mainly due to differences between industrial and laboratory procedures and the usage of certain wastes that already have added value in other circular economy chains. In addition, the assessment of such proposals commonly misses the environmental impact issue which is merely assumed to be positive. For these reasons this study, for the first time, has assessed together technological properties and the environmental impact of bricks made by strictly following industrial procedures. Hence, biomass bottom ash (BBA) was added at 9 replacement ratios, ranging from 2.5 to wt. 20.0\% for making extruded bricks subjected to industrial drying and firing curves. Physical, thermal and mechanical properties of fired products were properly assessed and compared with the requirements set forth by Chilean standards. In addition, a life cycle impact assessment was developed to compare the ecological footprint among series. Although mechanical and waterproof requirements may limit the replacement ratio for exposed bricks, the feasibility of using BBA at industrial scale has been successfully demonstrated. Regarding the environmental impact, the raw clay may be replaced without adversely causing toxicity levels to exceed mandatory limits. However, this study demonstrated that the incorporation of BBA increases CO2 emissions due to the decomposition of contained carbonates during the firing process which compromise the results in terms of global warming potential and water consumption which highly impact on human health and ecosystems quality.
Most agricultural wastes are rich in cellulose. Through chemical and/or mechanical processes, nanocellulose can be extracted to produce superabsorbent hydrogels. As soil amendments, superabsorbent hydrogels act as water and nutrient reservoirs when applied in agricultural fields. This article reviews the recent advances in agricultural waste-derived nanocellulose-based superabsorbent hydrogels and discusses the possible impacts of their applications in agriculture. The strengths and weaknesses of different current processes and techniques for nanocellulose extraction and hydrogel synthesis are compared. It is found that chemical methods are generally more cost-effective but may pose a threat to ecosystems, whereas physical methods are environmentally friendly but more complicated and expensive. The economic viability of using these novel superabsorbent hydrogels as soil amendments is also discussed, considering their potentials to reduce irrigation, enhance nutrient retention, and improve crop production. The results in this article indicates that the development of agricultural waste-derived superabsorbent hydrogels promotes environmental sustainability and circular economy in agriculture. The life cycles of new hydrogel products need to be explored in detail before optimal cellulose sources, reagents, and methods can be proposed for improvements. (C) Published by Elsevier Ltd.
Lignocellulose biorefinery encompasses process engineering and biotechnology tools for the processing of lignocellulosic biomass for the manufacturing of bio-based products (such as biofuels, bio-chemicals, biomaterials). While, lignocellulose biorefinery offers clear value proposition, success at industrial level has not been vibrant for the commercial production of renewable chemicals and fuels. This is because of high capital and operating expenditures, irregularities in biomass supply chain, technical process immaturity, and scale up challenges. As a result, commercial production of biochemicals and biofuels with right economics is still lagging behind. To hit the market place, efforts are underway by bulk and specialty chemicals producing companies like DSM (Succinic acid, Cellulosic ethanol), Dow-DuPont (1,3-Propanediol, 1,4-Butanediol), Clariant-Global bioenergies-INEOS (bio-isobutene), Braskem (Ethylene, polypropylene), Raizen, Gran-bio and POET-DSM (Cellulosic ethanol), Amyris (Farnesene), and several other potential players. This paper entails the concept of lignocellulose biorefinery, technical challenges for industrialization of renewable fuels and bulk chemicals and future directions.
Nanocellulose has potential applications across the several industrial sectors and addresses a lot of issues related to environmental concern. As biodegradable filler in composite manufacturing, coating, and self-standing thin films, it offers novel and promising properties. Very few available reviews report on nanocellulose-impregnated composite materials for food packaging. Nanocellulose reinforcement is found to be promising for mechanical and barrier properties of composite for biopolymer and synthetic polymer. In this paper, we provide a thorough review of recent advances of nanocellulose synthesis and its application as a filler material for production of nanocomposites to be used for food packaging. {[
Forty-eight growing Awassi lambs were used in a 70-day trial to investigate the effects of different levels of dietary sunflower hulls (SFH) on growth, rumen morphology, fiber digestibility and meat characteristics of lambs. Animals were randomly allocated to 4 groups with 3 replicates of 4 lambs each. The diet was composed of total mixed ration (TMR) without SFH (control group), and the TMR diet supplemented with SFH at a level of 5\% (SFH5), 10\% (SFH10) and 15\% (SFH15). Lambs in the treatment groups had greater BW changes (p = 0.04) and ADG (p = 0.04) than the lambs in the control group. Intake of dry matter, acid detergent fiber (ADF) and neutral detergent fiber (NDF) were also significantly (p < 0.05) higher in SFH15 compared to SFH10. Digestibility of ADL and empty stomach weight were also significantly (p < 0.05) higher in SFH10 and SFH15, respectively. Cooking loss, blood total cholesterol and total protein decreased significantly (p < 0.05) in SFH15. Ruminal lightness (L) and yellowness (b) also increased significantly (p < 0.05) in SFH15. We concluded that the TMR diet supplemented with up to 15\% SFH improved weight gain, digestibility, meat cooking loss and rumen color in Awassi lambs.
A novel adsorbent (FCDSBP) from de-pectinated sugar beet pulp (DSBP) was successfully prepared by loading the surface of citric acid modified DSBP (CDSBP) with amorphous Fe-oxide species and FCDSBP was used to investigated the removal of metal ions (Cu2+ and Pb2+) from aqueous solutions. The obtained composites were characterized by FTIR, XRD and SEM. According to all characterization results, amorphous iron oxides of FeOx type and hydroxylated oxide were located on the FCDSBP surface. Due to the presence of amorphous Fe-oxide species and hydroxylated oxide, the adsorption capacity of FCDSBP for Cu2+ and Pb2+ was approximately three times that of CDSBP. In addition, the obtained experimental data of adsorption of metal ions by the FCDSBP and CDSBP fitted the Langmuir isotherm model well, and the pseudo-second-order kinetic model could be used to describe adsorption process. According to the calculated thermodynamic parameters, the metal ions adsorption process was endothermic and spontaneous in nature.
The influence of operating conditions on the yield and quality of bio-oil obtained from black spruce wood mixture was studied using an auger reactor. Fast pyrolysis optimization through response surface analysis was carried out with four variables: pyrolysis temperature, solids residence time, nitrogen flow, and temperature of first stage of condensation. The optimal conditions obtained for bio-oil production were 555 degrees C, 129 s, 6.9 L/min, and 120 degrees C, respectively. The product yields were 38.61 wt.\% of biochar, 25.39 wt.\% of liquid, and 36.52 wt.\% of non-condensable gases Two liquid products were produced at the exit of the two condensers, following the concept of fractional condensation. The oily phase yield recovered in the first condenser was 10.59 wt.\%, with a 16.86 wt.\%, of moisture content. Physical properties of the oily phase were analyzed and compared with the ASTM standard D7544-12. Qualitative identification of chemical compounds was carried out for the oily phase which helped in pyrolysis optimization for the bio-oil production targeted towards its use as fuel in commercial burners. In addition, the oil produced here is one of the lowest in water and solids content, attributable to the unique feature of auger reactors without the need for additional treatments. (C) 2019 BRTeam. All rights reserved.
The present study investigated for the first time the efficacy of surfactant-assisted ionic liquid 1-ethyl3-methylimidazolium acetate ({[
This study explored the hydrolysis and fermentation of paper with hydrogen (H-2) and volatile fatty acid (VFA) recovery using a natural microbial consortium added to lysimeters. Serial dilutions of rumen fluid in natura were performed to obtain a fermentative nonmethanogen consortium, which was used as inoculum in lysimeters under two different incubation temperatures, Ll at 35 degrees C and L2 at 55 degrees C. H-2 was detected in both lysimeters: 791.5 mL (L1) and 70.4 mL (L2). In L1, the production of 16,856 mg L-1 acetic acid was likely due to the occurrence of homoacetogenesis. Under thermophilic conditions, L2, a low volume of H2 was detected, and the highlight was the production of ethanol and methanol at 2289 and 5614 mg L-1, respectively. According to the Shannon index, there was great diversity of microorganism populations in the rumen fluid in natura (6.34) compared with the purified rumen fluid (2.73), L1 (2.67) and L2 (3.21). The most abundant genus in the rumen fluid in natura was Prevotella (37.5 \%); in the purified consortium (68.7 \%) and L1 (63.8), Dysgonomonas; and in L2 (88.7 \%), Thermicanus. In conclusion, the temperature influenced the microbial community structure, the metabolic route and, consequently, the main byproducts produced by the fermentative activity at 35 degrees C and 55 degrees C. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
The present work reports the effects of adding an agro-industrial residue (peanut skin) to cassava starch-based foams developed by thermopressing process. For this purpose, foams composed of cassava starch (CS foams) and cassava starch added of 24\% (w/w) of peanut skin (CS/PS foams) were compared regarding their chemical structures, thermal, morphological and mechanical properties, moisture sorption isotherms, contact angle, and biodegradation. Results of dynamic mechanical analysis (DMA) showed the addition of peanut skin reduced the stiffness due to the increase of mobility of the starch chains. CS/PS foams exhibited a decrease in the storage modulus and glass transition temperatures as observed DMA. The addition of peanut skin did not influence on tensile stress and Young's modulus but reduced the tensile strain of the foams. The water contact angle of CS/PS foam was higher than CS foam, and as a result, CS/PS foams were found less hydrophilic than CS foams, which broaden the application of these materials. The reduction of hydrophilicity was related to the composition of the additive, mainly regarding lipids and proteins fractions, as well as to the interactions between cassava starch and peanut skin, reducing the availability of OH groups to bond with water. (C) 2019 Elsevier B.V. All rights reserved.
This work investigated the influence of chemical (Triton X-100) and biological surfactant preparation (rhamnolipids) in coconut husk hydrolysis that was subjected to pretreatment with acid-alkali or alkaline hydrogen peroxide. The natural and pretreated biomass was characterized using the National Renewable Energy Laboratory protocol analysis as well as X-ray diffraction and scanning electron microscopy. The results demonstrated that in terms of the total reducing sugars, there was no significant difference between the hydrolysis using Triton X-100 and rhamnolipids, regardless of the pretreatment. A cellulosic conversion value as high as 33.0\% was obtained in experiments with rhamnolipids. The coconut husk was observed to be a potential biomass that could produce second generation ethanol, and the rhamnolipid preparation can be used to support for the enzymatic hydrolysis, enhancing the advantage of cellulose conversion into glucose over chemical surfactants because it is an environmentally friendly approach. (C) 2017 Elsevier Ltd. All rights reserved.
The pyrolysis of waste plastic and lignocellulosic material feedstocks increases the hydrogen/carbon ratio of the plastic-biomass mixture and may be advantageous for refining the properties of pyrolysis oil, which can be directly used as a fuel without any need for upgrading by catalytic hydrodeoxygenation. In this paper, high-density polyethylene (HDPE) and brown salwood were tested in a custom-built laboratory-scale fixed-bed reactor to investigate the co-pyrolysis reaction at temperatures ranging from 500 to 650 degrees C, nitrogen flow rates ranging from 40 to 160 mL min-1, and HDPE-to-biomass ratios ranging from 0.1 to 0.9. The results revealed that the temperature mostly influenced the pyrolysis products, whereas increasing the temperature to 600 degrees C promoted pyrolysis oil production, reaching a yield of 35.10 +/- 1.20 wt\%. Further increasing the reaction temperature to 650 degrees C decreased the yield to 34.57 +/- 0.49 wt\% because secondary cracking reactions produce a noncondensable gas rich in hydrocarbons. Physicochemical analysis of the pyrolyzed organic phase revealed a gross calorific heating value of up to approximately 38.19 MJ kg-1. Additionally, co-pyrolysis of HDPE improved the production of furans, and acid derivatives were obtained in the aqueous fraction via the thermal conversion of hemicellulose and lignin; conversely, the obtained char exhibited a notably low surface area and few superficial micropores and was used to further develop activated carbon for use as a catalyst in the catalytic pyrolysis of waste materials.
Lignocellulosic biowastes are rich in sugars and may be used as low-cost feed to produce environmentally friendly fuels such as hydrogen (H-2). Poplar biomass is available in large quantities as a sugar rich biowaste. Few studies have evaluated bacterial H-2 production using well-defined mixed cultures (DMC) under non-sterile continuous culture conditions. DMC composed of high H-2-producing bacteria may circumvent the potential risk of a single bacterial culture being out-competed under non-sterile conditions. The novelty of this study lies in the continuous production of H-2 from poplar biomass using DMC in immobilized state under non-sterile conditions. Under optimized continuous culture conditions with DMC immobilized on coconut coir, a H-2 yield of 2.83 mol/mol of hexose was steadily obtained over a period of 40 days, which was four-fold higher compared to that obtained with Bacillus thuringiensis. This approach may enable to meet the increasing demand for cleaner energy-rich fuels on a large-scale in a steady manner. (C) 2020 Elsevier Ltd. All rights reserved.
This review paper encompasses the inclusive approach of lime sludge valorization in construction materials. Research studies based on cement and aggregate replacement by lime sludge concludes that 10-30\% lime sludge is gainfully utilized in sustainable concrete and mortar. Additional prospect for lime sludge application in construction material is the production of cement and ceramics. Significant use of lime sludge in combination with supplementary cementitious materials such as silica fume, nanosilica and fly ash is recommended for the production of cement components and ceramics. The recommendations are also suggested in accordance with the outcome of the study. (C) 2019 Elsevier Ltd. All rights reserved.
In this study, we evaluated for the first time the capacity of six biochars to remove gaseous ozone, adsorbed nitrate and aqueous bisphenol A (BPA). An experimental setup was developed to study the heterogeneous chemistry of ozone and nitrate on the surface of biochars. Biochars showed excellent performance in removing ozone (55 ppbv) for periods up to 24 h, and no volatile byproducts were observed during the reaction process. Challenging biochars with adsorbed nitrate led to the formation of reduced nitrogen oxides (NO and NO2) under UV irradiation. The photoreduction of nitrate was induced by the reduced carbon present in the biochars which led to the formation of nitrite followed by photoreduction to NO in the gas phase and on the surface. Adsorption capacities of biochars for removing BPA from water were also estimated. After long-term aging by ozone, BPA adsorption capacities of all biochars did not change while they were found to decrease slightly after nitrate aging. This could be attributed to partial oxidation of biochar surface as evidenced by infrared analysis and the formation of surface-hydroxyl and -carbonyl groups. This study will allow a better evaluation of biochars as promising materials for removal of air and aqueous pollutants.
Firstly, foam trays were produced from glyoxal cross-linked wheat, potato and corn starches and their mixtures. The most suitable starch type for starch-based foam tray production was selected according to the level of water absorption, density, surface and cross-section micrographs of the foam trays. It was decided that a wheat and potato starch blend was the most suitable starch source for producing the foam trays because they have the lowest water absorption percentage (25.5 +/- 0.7\%), low density (0.17 +/- 0.01 g/cm(3)) and a smooth surface. Potato-wheat starch foam trays with fibres were produced by adding wheat and wood fibres. Unlike wood fibres addition, wheat fibres significantly decreased the percentage of water absorption (16.63 +/- 1.2\%) and density (0.115 +/- 0.013 g/cm(3)) of the tray. Also, the trays including wheat fibre had a lighter colour than the wheat-potato starch tray. To further reduce water absorption of the tray, the trays were made by adding two different types of lipids (beeswax or shortening and three different types of filler materials-kaolin, montmorillonite or zinc oxide nanoparticles). According to the level of water absorption of the trays, it was decided that shortening and zinc oxide nanoparticles, in addition to kaolin, were respectively the most suitable lipid and filler materials. The foam trays were produced by adding these supplementary materials. The addition of shortening slightly, zinc oxide nanoparticles moderately and kaolin greatly increased the density of the wheat potato starch tray including fibre. However, the percent of water absorption of the trays containing wheat fibre + shortening or wheat fibre + shortening + zinc oxide nanoparticles decreased 6.4 +/- 0.01 and 5.9 +/- 0.3\%, respectively.
This study reported on the feasibility and practicability of Cr(NO3)(3) hydrolysis to isolate cellulose nanocrystals (CNCCr(NO3)(3)) from native cellulosic feedstock. The physicochemical properties of CNCCr(NO3)3 were compared with nanocellulose isolated using sulfuric acid hydrolysis (CNCH2SO4). In optimum hydrolysis conditions, 80 degrees C, 1.5 h, 0.8 M Cr(NO3)(3) metal salt and solid-liquid ratio of 1: 30, the CNCCr(NO3)3 exhibited a network-like long fibrous structure with the aspect ratio of 15.7, while the CNCH2SO4 showed rice-shape structure with an aspect ratio of 3.5. Additionally, Cr(NO3)(3)-treated CNC rendered a higher crystallinity (86.5\% +/- 0.3\%) with high yield (83.6\% +/- 0.6\%) as compared to the H2SO4-treated CNC (81.4\% +/- 0.1\% and 54.7\% +/- 0.3\%, respectively). Furthermore, better thermal stability of CNCCr(NO3)3 (344 degrees C) compared to CNCH2SO4 (273 degrees C) rendered a high potential for nanocomposite application. This comparable effectiveness of Cr(NO3)(3) metal salt provides milder hydrolysis conditions for highly selective depolymerization of cellulosic fiber into value-added cellulose nanomaterial, or useful chemicals and fuels in the future.
Thermal assisted alkaline pretreatment (TAAP) of rice husk (RH) was investigated to facilitate enzymatic saccharification by enhancing the enzyme accessibility to cellulosic components. Statistically guided experiments based on the Box-Behnken design involving four factors viz. biomass loading, particle size, NaOH loading and reaction time was considered for optimization. The maximum sugar yield of 371 mg g(-1) biomass was obtained at optimized pretreatment condition {[
Pineapple shell, considered a waste in the juice industry, was used as a reinforcement material to produce biodegradable foam trays (FTs) based on cassava starch by a compression molding process. These foams were prepared with different starch/fiber ratios and then were characterized according to their microstructure and physical and mechanical properties. The starch/fiber ratio of 95/5 showed the lowest values of thickness and density (2.58 mm and 367 kg m(-3), respectively). There was a good distribution of the pineapple shell fiber throughout the polymeric matrix. All FTs showed a semicrystalline structure and 95/5 ratio showed the highest crystallinity index (CI) value (39\%). In addition, this ratio improved the tensile strength of the FTs, obtaining similar values to expanded polystyrene (EPS) samples, used as the reference material. Nevertheless, all FTs reinforced with pineapple shell fiber showed high water absorption capacity (WAC); therefore, future studies should focus on to improve the physicochemical and structural properties of the cassava starch-based foams, considering the promising potential of this novel biodegradable material for dry food packaging, such as a viable alternative to reduce the use of petroleum-based materials such as commercial EPS trays.
Conventional phototrophic cultivation for micro-algae production suffers from low and unstable biomass productivity due to limited and unreliable light transmission outdoors. Alternatively, the use of a renewable lignocellulose-derived carbon source, cellulosic hydrolysate, offers a cost-effective and sustainable pathway to cultivate microalgae heterotrophically with high algal growth rate and terminal density. In this study, we evaluate the feasibility of cellulosic hydrolysate-mediated hetero-trophic cultivation (Cel-HC) for microalgae production by performing economic and environmental comparisons with photo-trophic cultivation through techno-economic analysis and life cycle assessment. We estimate a minimum selling price (MSP) of 4722 USD/t for producing high-purity microalgae through Cel-HC considering annual biomass productivity of 300 t (dry weight), which is competitive with the conventional phototrophic raceway pond system. Revenues from the lignocellulose-derived co-products, xylose and fulvic acid fertilizer, could further reduce the MSP 2976 USD/t, highlighting the advantages of simultaneously producing high-value products and biofuels in an integrated biorefinery scheme. Further, Cel-HC exhibits lower environmental impacts, such as cumulative energy demand and greenhouse gas emissions, than phototrophic systems, revealing its potential to reduce the carbon intensity of algae-derived commodities. Our results demonstrate the economic and environmental competitiveness of heterotrophic microalgae production based on renewable bio-feedstock of lignocellulose.
Composting is a biodegradation and transformation process that converts lignocellulosic biomass into valueadded products, such as humic substances (HSs). However, the recalcitrant nature of lignocellulose hinders the utilization of cellulose and hemicellulose, decreasing the bioconversion efficiency of lignocellulose. Pretreatment is an essential step to disrupt the structure of lignocellulosic biomass. Many pretreatment methods for composting may cause microbial inactivation and death. Thus, the pretreatment methods suitable for composting can promote the degradation and transformation of lignocellulosic biomass. Therefore, this review summarizes the pretreatment methods suitable for composting. Microbial consortium pretreatment, Fenton pretreatment and surfactant-assisted pretreatment for composting may improve the bioconversion process. Microbial consortium pretreatment is a cost-effective pretreatment method to enhance HSs yields during composting. On the other hand, the efficiency of enzyme production during composting is very important for the degradation of lignocellulose, whose action mechanism is unknown. Therefore, this review describes the mechanism of action of lignocellulase, the predominant microbes producing lignocellulase and their related genes. Finally, optimizing pretreatment conditions and increasing enzymatic hydrolysis to improve the quality of composts by controlling suitable microenvironmental factors and core target microbial activities as a research focus in the bioconversion of lignocellulose during composting in the future.
Lignin is a complex phenolic biopolymer present in plant cell walls and a by-product of the cellulose pulping industry. Lignin has functional properties, such as antioxidant activity, that make it a potential natural active ingredient for health-care products. However, not all safety aspects of lignin fractions have been adequately investigated. Herein, we evaluated the antioxidant and genotoxic potential of two hardwood kraft lignins (F3 and F5). The chemical characterization of F3 and F5 demonstrated their thermal stability and the presence of different phenolic units, while the DPPH assay confirmed the antioxidant activity of these lignin fractions. Despite being antioxidants in the DPPH assay, F3 and F5 were capable of generating intracellular reactive oxygen species (ROS) and subsequently causing oxidative DNA damage (Comet assay) in HepG2 cells. The biological relevance of the DPPH assay might be uncertain in some cases; therefore, we suggest combining in chemico tests with biological system-based tests to determine efficacy and safety levels of lignins and define appropriate applications of lignins for consumer products. Moreover, kraft lignins obtained by acid precipitation may pose risks to human health; however, as genotoxicity is not the sole endpoint of toxicity required in hazard assessments, additional toxicological evaluations are needed. (c) 2021 Elsevier B.V. All rights reserved.
This study reports on the delignification of Prosopis juliflora biomass using microwave-assisted alkaline pretreatment. Response surface methodology was employed to analyze the effect of process variables on delignification. Four independent process variables such as microwave irradiation power (270-450 W), microwave irradiation time (3-5 min), alkali concentration (0.75-1.25\% wt/vol) and liquid to solid ratio (LSR; 10-20 mL/g) were analyzed. A second-order nonlinear equation was developed to validate the model. The experimental results suggested that all the variables exhibited a similar response. The developed model was statistically valuated using analysis of variance. The optimum conditions determined from the study were as follows: microwave power of 360 W, irradiation time of 4.40 min, alkali concentration of 1.24\% wt/vol and LSR of 13.16 mL/g. Maximum delignification of 75.12\% was obtained using microwave-assisted alkali pretreatment method. The delignified Prosopis juliflora biomass was characterized using scanning electron microscopy and Fourier transform infrared spectroscopy studies. It was confirmed that microwave-assisted alkali pretreatment for a short duration facilitated maximum removal of lignin from biomass. The present study, therefore, helps in developing a suitable strategy both for satisfying the energy need and management of the exotic weed.
In this study, effects of different pretreatment methods on the enzymatic digestibility of Pennisetum alopecuroides, a ubiquitous wild grass in China, were investigated to evaluate its potential as a feedstock for biofuel production. The stalk samples were separately pretreated with H2SO4, NaOH and FeCl3 solutions of different concentrations at 120 degrees C for 30 min, after which enzymatic hydrolysis was conducted to measure the digestibility of pretreated samples. Results demonstrated that different pretreatments were effective at removing hemicellulose, among which ferric chloride pretreatment (FCP) gave the highest soluble sugar recovery (200.2 mg/g raw stalk) from the pretreatment stage. In comparison with FCP and dilute acid pretreatment (DAP), dilute alkaline pretreatment (DALP) induced much higher delignification and stronger morphological changes of the biomass, making it more accessible to hydrolysis enzymes. As a result, DALP using 1.2\% NaOH showed the highest total soluble sugar yield through the whole process from pretreatment to enzymatic hydrolysis (508.5 mg/g raw stalk). The present work indicates that DALP and FCP have the potential to enhance the effective bioconversion of lignocellulosic biomass like P. alopecuroides, hence making this material a valuable and promising energy plant.
We aimed to develop a simple and low-cost method for the production of high-performance cellulose nanomaterials from renewable and sustainable resources. Here, cellulose microcrystals (CMCs) were prepared by controlled acidic and basic hydrolysis of cotton from textile industry wastes. The resulted CMCs were further converted into cellulose nanocrystals (CNCs) with high crystallinity by acidic hydrolysis. The physicochemical characteristics and morphological feature of CMCs and CNCs were studied by various analytical techniques such as UV-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), Fluorescence spectroscopy, Atomic force microscopy (AFM), High-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The isolated CNCs possess a needle-like morphological structure with the longitudinal and lateral dimensions of 180 +/- 60 nm, 10 +/- 1 nm, respectively. The AFM result reveals that the CNCs have a high aspect ratio of 40 +/- 14nm and the average thickness of 6.5 nm. The XRD and TEM analysis indicate that the synthesized CNCs possess face-centered cubic crystal structure. Preliminary experiments were carried out to fabricate CNCs incorporated poly (vinyl alcohol) (PVA) film. The results suggest that the concept of waste to wealth could be well executed from the prepared CNCs, which have great potential for various applications including bio-sensors, food packaging and drug delivery applications. (C) 2017 Elsevier B.V. All rights reserved.
Xylan-containing fruit wastes can be valorized efficiently by xylanolytic microbes for the production of biofuels. The current study aimed to isolate and screen ethanol-producing bacteria from rotten fruit wastes that ferment xylose. Sixteen bacteria were isolated by spread-plate method from apple, banana, guava, and grape wastes on a solid medium supplemented with 5\% xylan. The potential of ten bacterial isolates to degrade xylose was checked by biochemical tests. Bacterial strains XA2, XG1, and XG3 showed maximum CO2 production in Durham tubes. XA2, XG2, and XG3 showed maximum zones (1-2.6 cm) by Congo-red staining. XG2, XG3, and XA2 showed maroon and pink color with triphenyltetrazolium demonstrating degradation of xylan. The selected bacterial isolates were subjected to ferment 5\% xylan-supplemented minimal medium for ten days to investigate etha-nologenesis. Bacterial isolate XG2 produced maximum ethanol of 3.069 +/- 0.738 g/L on day 8. The sugar con-tents in the fermentation medium continued to be decreased as the experiments proceeded up to 10 days. Maximum enzyme activity was observed by both XA2 and XG2 as 0.817 +/- 0.036 and 0.917 +/- 0.059 mu mol/min/ L. Strains XA2 and XG2 were characterized as Enterococcus faeceum XA2 and Bacillus cereus XG2 (Accession Nos. OM971654 and OM970803) by comparing their 16 S rRNA gene sequences with the available sequences in GenBank each having resemblance of 98 \%. The present study highlights the dual capacity of bacteria to degrade xylan as well as promote ethanol production by employing xylan as a carbon source.
Dilute sulfuric acid pretreatment is effective at producing a xylose-rich hydrolysate from lignocellulosic biomasses, however inhibitory compounds, released during the processes, can affect the metabolism of fermenting microorganisms, thus reducing the biomass formation, yields and productivity. In this scenario, two approaches for hemicellulosic hydrolysate detoxification were evaluated: liquid-liquid extraction (process 1) and evaporation followed by liquid-liquid extraction (process 2), using 1-butanol, isobutyl acetate and MIBK as extractants. The hydrolysates (detoxified and non-detoxified) fermentations were evaluated by S. stipitis and S. passalidarum. Although process 1 has provided good removal efficiencies, acetic acid concentration in detoxified hydrolysate was still relatively high, while process 2 resulted in 90\% of global acetic acid removal. S. passalidarum detoxified hydrolysates fermentation showed higher ethanol yields and productivities than S. stipitis. An inhibitory effect of 1-butanol has been achieved for both yeasts, resulting in low sugar consumption and consequently low ethanoltiters. Process 2 with MIBK led to 69.0\% of phenolics; 85.4\% of acetic acid and 100.0\% of HMF and furfural extractions, with ethanol yield and productivity of 75.6\% and 0.41 g/g, respectively. This process comes up as a promising method once it provides toxic-compounds removal without carbohydrates losses and allows an extractant-recycling integrated process.
The results of a 30 year U.S.-Hungarian research cooperation are surveyed. The head of the cooperating U.S. laboratory, Michael J. Antal, Jr., died on Oct 21, 2015. He was a leading person in biomass research. The collaboration started with pyrolysis studies. In this phase of the work, the aim was to clarify the factors that enhance the formation of the valuable volatile products ({''
In this paper, response surface methodology (RSM) approach using Central Composite Design (CCD) is applied to develop mathematical model and optimize process parameters for Cr (VI) removal from aqueous streams using weakly anionic resin Amberlite IRA 96. The individual and combined effect of four process parameters, i.e. contact time, initial solution pH, initial Cr (VI) concentration and resin dose on Cr adsorption were studied. Analysis of variance (ANOVA) showed the relative significance of process parameters in removal process. Initial solution pH and resin dose were found to be more significant than contact time and initial Cr (VI) concentration. The second-order regression model was developed to predict the removal efficiency using Design Expert software. The optimal conditions to remove Cr from aqueous solution at constant temperature of 30 degrees C and stirring speed of 250 rpm were found to be contact time 62.5 min, pH 1.96, initial Cr (VI) concentration 145.4 mg/L, and resin dose 8.51 g/L. At these conditions, high removal efficiency (93.26\%) was achieved. FTIR and EDX analysis were conducted to interpret the functional groups involved during the Cr-resin interaction. (C) 2012 Elsevier B.V. All rights reserved.
Two different corncob samples from different continents and climates were studied by thermogravimetry at linear and nonlinear heating programs in inert gas flow. A distributed activation energy model (DAEM) with three and four pools of reactants (pseudocomponents) was used due to the complexity of the biomass samples of agricultural origin. The resulting models described well the experimental data. When the evaluation was based on a smaller number of experiments, similar model parameters were obtained which were suitable for predicting experiments at higher heating rates. This test indicates that the available experimental information was sufficient for the determination of the model parameters. The checks on the prediction capabilities were considered to be an essential part of the model verification. In another test, the experiments of the two samples were evaluated together, assuming more or less common kinetic parameters for both cobs. This test revealed that the reactivity differences between the two samples are due to the differences in their hemicelluloses and extractives. The kinetic parameter values from a similar earlier work on other biomasses (Varhegyi, G.; Bobaly, B.; Jakab, E.; Chen, H. Energy Fuels, 2011, 25, 24-32) could also been used, indicating the possibilities of a common kinetic model for the pyrolysis of a wide range of agricultural byproduct.
The Cfl xyn11A gene, encoding the endo-1,4-beta-xylanase Cfl Xyn11A from Cellulomonas flavigena, was isolated from a genomic DNA library. The open reading frame of the Cfl xyn11A gene was 999 base pairs long and encoded a polypeptide (Cfl Xyn11A) of 332 amino acids with a calculated molecular mass of 35,110 Da. The Cfl xyn11A gene was expressed in Escherichia coli and the recombinant enzyme, with an estimated molecular weight of 31 kDa was purified and xylanase activity was measured. Cfl Xyn11A showed optimal activity at pH 6.5 and 55 degrees C. The enzyme demonstrated moderate thermal stability as Cfl Xyn11A maintained 50\% of its activity when incubated at 55 degrees C for 1 h or at 45 degrees C for 6 h. This is the first report describing the cloning, expression and functional characterization of an endo-1,4-beta-xylanase-encoding gene from C. flavigena. Cfl Xyn11A may be suitable for industrial applications in the food and feed industries, or in the pre-treatment of lignocellulosic biomass required to improve the yields of fermentable sugars for bioethanol production. (C) 2010 Elsevier Ltd. All rights reserved.
The recalcitrance of lignocellulosic biomass to enzymatic release of sugars (saccharification) currently limits its use as feedstock for biofuels. Enzymatic hydrolysis of untreated aspen wood releases only 21.8\% of the available sugars due primarily to the lignin barrier. Nature uses oxidative enzymes to selectively degrade lignin in lignocellulosic biomass, but thus far, natural enzymes have been too slow for industrial use. In this study, oxidative pretreatment with commercial peracetic acid (470 mM) removed 40\% of the lignin (from 19.9 to 12.0 wt.\% lignin) from aspen and enhanced the sugar yields in subsequent enzymatic hydrolysis to about 90\%. Increasing the amount of lignin removed correlated with increasing yields of sugar release. Unfortunately, peracetic acid is expensive, and concentrated forms can be hazardous. To reduce costs and hazards associated with using commercial peracetic acid, we used a hydrolase to catalyze the perhydrolysis of ethyl acetate generating 60-70 mM peracetic acid in situ as a pretreatment to remove lignin from aspen wood. A single pretreatment was insufficient, but multiple cycles (up to eight) removed up to 61.7\% of the lignin enabling release of > 90\% of the sugars during saccharification. This value corresponds to a predicted 581 g of fermentable sugars from 1 kg of aspen wood. Improvements in the enzyme stability are needed before the enzymatically generated peracetic acid is a commercially viable alternative.
BACKGROUND: Xylitol is a sugar alcohol (polyalcohol) with many interesting properties for pharmaceutical and food products. It is currently produced by a chemical process, which has some disadvantages such as high energy requirement. Therefore microbiological production of xylitol has been studied as an alternative, but its viability is dependent on optimisation of the fermentation variables. Among these, aeration is fundamental, because xylitol is produced only under adequate oxygen availability. In most experiments with xylitol-producing yeasts, low oxygen transfer volumetric coefficient (K(L)a) values are used to maintain microaerobic conditions. However, in the present study the use of relatively high K(L)a values resulted in high xylitol production. The effect of aeration was also evaluated via the profiles of xylose reductase (XR) and xylitol clehydrogenase (XD) activities during the experiments. RESULTS: The highest XR specific activity (1.45 +/- 0.21 U mg(protein)(-1)) was achieved during the experiment with the lowest K(L)a value (12 h(-1)), while the highest XD specific activity (0.19 +/- 0.03 U mg(protein)(-1)) was observed with a K(L)a value of 25 h(-1). Xylitol production was enhanced when K(L)a was increased from 12 to 50 h(-1), which resulted in the best condition observed, corresponding to a xylitol volumetric productivity of 1.50 +/- 0.08 g(xylitol) L-1 h(-1) and an efficiency of 71 +/- 6.0\%. CONCLUSION: The results showed that the enzyme activities during xylitol bioproduction depend greatly on the initial KLa value (oxygen availability). This finding supplies important information for further studies in molecular biology and genetic engineering aimed at improving xylitol bioproduction. (C) 2008 Society of Chemical Industry
The rapid urbanization of developed countries and the difficulty in disposing of agricultural wastes have created opportunities for the construction industry to use agricultural wastes. A wide variety of agricultural waste materials are already in use with concrete as substitutes for cement and aggregates, as well as reinforcing materials. This study reviews the available literature published from 1935 to 2022 on agricultural wastes being used as building materials. The research utilizes a bibliographic approach based on the Scopus database. This article retrieves data employing the Scopus database and incorporates 671 articles based on the keywords, agricultural wastes used as building materials. The scientometric analysis is the second step, wherein the patterns of the obtained articles are investigated with various factors such as countries with the most publications, sources that have the most publications, most frequently appearing keywords, and articles with more relevant research works. A summary of the results obtained at various stages of the research is depicted in each phase. Detailed quantitative and qualitative discussions are also conducted to achieve the three main objectives: the summarization of quantitative data, discussion of the existing application, and identification of future research directions. These findings serve the future endeavor of agricultural waste-to-building materials' incineration academic research. The scientometric review paves the way for academics from various nations to impart novel ideas and information and foster research collaboration.
Overpopulation and rapid development have put an increasing burden on the environment, leading to various water crisis. Importing water from abandoned mines as an alternative raw water source could be the next answer to alleviate water scarcity problems globally. However, due to its high heavy metals content, there is a need to find an economical and effective method to remove heavy metals before reusing it as potable water source. Biochar, a low-cost and carbon-rich biosorbent, has received increasing attention on its application as a remediating agent to remove heavy metals from water. Previous studies have revealed the potential properties of biochar as a heavy metal removal agent including high cation exchange capacity, high surface area, active surface functional groups, as well as efficient adsorption. Apparently, the most important factor influencing the sorption mechanism is the type of feedstock materials. Spent mushroom compost (SMC), a waste product from mushroom cultivation, has been found as an excellent biosorbent. SMC has received global attention as it is low cost and eco-friendly. It also has been proved as an efficient heavy metals remover from water. Nevertheless, its application as biochar is still scarce. Therefore, this review focuses on the potential of transforming SMC into modified biochar to remove heavy metals, especially from abandoned mining water. The present review emphasizes the current trends in adsorption methods for heavy metal removal from water, assembles data from previous studies on the feedstock of biosorbents to biochars, and discusses the potentials of SMC as a biochar for water treatment.
The discharge of large amounts of effluents contaminated with gentian violet (GV) and phenol red (PR) threatens aquatic flora and fauna as well as human health, which is why these effluents must be treated before being discarded. This study seeks the removal of dyes, using water lily (Eichhornia crassipes) as an adsorbent with different pretreatments. PR and GV were analyzed by a UV-visible spectrophotometer. Equilibrium experimental data showed that Freundlich is the best model to fit PR and SIPS for GV, showing that the adsorption process for both dyes was heterogeneous, favorable, chemical (for GV), and physical (for PR). The thermodynamic analysis for the adsorption process of both dyes depends directly on the increase in temperature and is carried out spontaneously. The Pseudo first Order (PFO) kinetic model for GV and PR is the best fit for the dyes having an adsorption capacity of 91 and 198 mg/g, respectively. The characterization of the materials demonstrated significant changes in the bands of lignin, cellulose, and hemicellulose, which indicates that the functional groups could participate in the capture of the dyes together with the electrostatic forces of the medium, from which it be concluded that the adsorption process is carried out by several mechanisms.
Lignocellulosic biomass generated from different sectors (agriculture, forestry, industrial) act as biorefinery precursor for production of second-generation (2G) bioethanol and other biochemicals. The integration of various conversion techniques on a single platform under biorefinery approach for production of biofuel and industrially important chemicals from LCB is gaining interest worldwide. The waste generated on utilization of bio-resources is almost negligible or zero in a biorefinery along with reduced greenhouse gas emissions, which supports the circular bioeconomy concept. The economic viability of a lignocellulosic biorefinery depends upon the efficient utilization of three major components of LCB-cellulose, hemicellulose and lignin. The heterogeneous structure and recalcitrant nature of LCB is main obstacle in its valorization into bioethanol and other value-added products. The success of bioconversion process depends upon methods used during pre-treatment, hydrolysis and fermentation processes. The cost involved in each step of the bioconversion process affects the viability of cellulosic ethanol. The lignocellulose biorefinery has ample scope, but much-focused research is required to fully utilize major parts of lignocellulosic biomass with zero wastage. The present review entails lignocellulosic biomass valorization for ethanol production, along with different steps involved in its production. Various value-added products produced from LCB components were also discussed. Recent technological advances and significant challenges in bioethanol production are also highlighted in addition to future perspectives.
Biochar can be fabricated from waste biomass via thermochemical conversion. Here we investigated the production of activated biochar from cow manure via three different approaches, i.e., hydrochar-impregnation (HAC), impregnated biomass pyrolysis (PAC) and one-pot hydrothermal carbonization (HOC). The surface area of HAC, HOC and PAC increased from 81.00, 307.06 and 333.03 m(2)/g to 637.75, 791.20 and 841.91 m(2)/g, respectively, with the increased addition ratio of ZnCl2 to biomass/ biochar (0.5:1 similar to 4:1). HOC had significantly superior performance in the surface area, porosity and aromatization degree to HAC, whereas it had similar porosity and surface functional groups, but slightly different surface morphology to PAC. Specifically, HOC and PAC were characterized with higher amounts of surface functional groups including carboxyl -COOH and phenolic -OH, whereas HAC was detected with more C-O bond. HOC gained a highest degree of aromatization with a maximum sorption capacity of 102.72 mg phenol/g, which was in between HAC (42.12 mg/g) and PAC (125.70 mg/g). The study on phenol sorption revealed that not only surface functional groups but also porosity played critical roles in pollutant sorption. The well-fitted PSO kinetic model further verified that the sorption using HOC and PAC was involved with chemical and physical processes, whereas the sorption using HAC was accompanied with higher chemisorption and lower physical sorption due to its ample surface groups but poor porosity. In addition, energy analysis revealed that HOC is a simple-operation and energy-effective process to prepare activated biochar in comparison to HAC and PAC.
To overcoming the natural recalcitrance of cellulose for glucose production via enzymatic hydrolysis, a new strategy of destroying hydrogen bond donor to reconstruct cellulose's hydrogen bonding network was developed via a mild reversible reaction of cellulose with CO2 catalyzed by organic bases. The reaction dynamics of cellulose with CO2 in the presence of organic bases was studied by using in situ IR. Investigation also included how the organic bases in pretreatment media and pretreatment parameters including CO2 pressure, pretreatment temperature and time affected the physical-chemical structure of cellulose by Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Atomic force microscopy (AFM) and subsequent enzymatic scarification of cellulose. The findings showed that dissolution activation efficiency significantly correlated to various parameters, that can be optimized to be the tetramethyl guanidine (TMG)/CO2/DMSO solvent system at 50 degrees C, 2 MPa of CO2 for 2 h, by which a complete transformation the cellulose crystalline structure from I to II, and 100\% glucose yield were achieved. The recyclability and usability are also investigated.
Textile waste torrefaction was investigated as a novel means to assist in waste valorization and energy management practices. This study analyzed the thermal behavior and fuel properties of textile waste subjected to torrefaction at 225, 250, 275 and 300 degrees C for 1 and 3 h at a constant heating rate of 15 degrees C/min. The energy and carbon contents of torrefied textiles were greatly enhanced whilst unusually high energy yields above 100\% were recorded due to the energy densification process. Reduced atomic H/C and 0/C ratios revealed that the fuel characteristics and reactivity of torrefied textiles converged towards those of coal. FTIR analysis indicated that torrefaction altered the chemical structure of textile waste with respect to its hemicellulose and cellulose contents. A strong linear correlation was observed between mass loss and the energy properties of torrefied textile biochar. This demonstrated the effectiveness of mass loss as a synthetic indicator of the degree of torrefaction. The analytical expressions derived experimentally represent essential tools that can be used in the optimization of the torrefaction process. Torrefied textiles can eventually assist in the displacement of important fractions of coal in thermal conversion systems in the long run.
Ionic liquids (ILs) were used in the dissolution of oil palm biomass, primarily empty fruit bunches (EFB), oil palm fronds (OPF), and oil palm trunks (OPT). These ILs acted as alternative solvents that could dissolve biopolymer molecules up to 5 wt.\%. The IL, {[
Wound dressings are devices used to stop bleeding and provide appropriate environmental conditions to accelerate wound healing. The effectiveness of wound dressing materials can be crucial to prevent deaths from excessive bleeding in surgeries and promote complete restoration of the injury. Some requirements for an ideal wound dressing are rapid hemostatic effect, high swelling capacity, antibacterial properties, biocompatibility, biodegradability, and mechanical strength. However, finding all these properties in a single material remains a challenge. In this context, nanocomposites have demonstrated an excellent capacity for this application because of their multifunctionality. One of the emerging materials used in nanocomposite manufacture is cellulose nanocrystals (CNCs), which are rod-like crystalline nanometric structures present on cellulose chains. These nanoparticles are attractive for wound healing applications because of their high aspect ratio, high mechanical properties, functionality and low density. Hence, this work aimed to present an overview of nanocomposites constituted by CNCs for wound healing applications. The review focuses on the most common materials used as matrices, the types of dressing, and their fabrication techniques. Novel wound dressings composites have improved hemostatic, swelling, and mechanical properties compared to other pure biopolymers while preserving their other biological properties. Films, nanofibers mats, sponges, and hydrogels have been prepared with CNCs nanocomposites, and in vitro and in vivo tests have proved their suitability for wound healing.
Pretreatment is very important for improvement of the biogas production from biomass in anaerobic digestion (AD) process, especially for lignocellulosic substrates. Hydrogen peroxide pretreatment (HPP) was used to enhance the AD of Miscanthus floridulus. Results showed that the maximum methane yield was produced at 0.8\% H2O2 concentration at neutral pH, which was 278.7 mL/g VS (volatile solid) and increased by 49\% compared to untreated sample. The results of XRD (X-ray diffraction) revealed that HPP process could marginally decrease crystallinity of cellulose which could be beneficial for better substrate utilization. In addition, SEM (scanning electron microscope) analysis suggested that pretreated miscanthus had a more porous structure compared to untreated substrate. Thus HPP is an environmental friendly and economical pretreatment method for AD of miscanthus. (C) 2017 Elsevier Ltd. All rights reserved.
Controlled depolymerization of cellulose is essential for the production of valuable cellooligosaccharides and cellobiose from lignocellulosic biomass. However, enzymatic cellulose hydrolysis involves multiple synergistically acting enzymes, making difficult to control the depolymerization process and generate desired product. This work exploits the varying adsorption properties of the cellulase components to the cellulosic substrate and aims to control the enzyme activity. Cellulase adsorption was favored on pretreated cellulosic biomass as compared to synthetic cellulose. Preferential adsorption of exocellulases was observed over endocellulase, while -glucosidases remained unadsorbed. Adsorbed enzyme fraction with bound exocellulases when used for hydrolysis generated cellobiose predominantly, while the unadsorbed enzymes in the liquid fraction produced cellooligosaccharides majorly, owing to its high endocellulases activity. Thus, the differential adsorption phenomenon of the cellulase components can be used for the controlling cellulose hydrolysis for the production of an array of sugars.
Lignin, which is considered one of the most recalcitrant components, limits the enzymatic hydrolysis of cellulose. When ball-milled lignin from switchgrass ranging from 21.4 to 64.3 mg/mL was added to a cellulose substrate (Avicel), the glucose release decreased from 17.4 to 22.4\% compared to the hydrolysis rate of zero lignin addition. However, the cellulose decreasing conversion was reduced to 8.5\% with 21.4 mg/mL ammonia fiber expansion (APEX)-treated lignin addition, as a result of the structural modification by AFEX pretreatment. The inhibitory effect of lignin was stronger on cellulose hydrolysis than on hemicellulose hydrolysis. The results showed that the free lignin released from biomass reduced the impact of the added lignin and that the AFEX pretreatment intensity was the key factor in increasing the enzymatic efficiency. The lignin structural modifications by AFEX pretreatment, such as slight increases in the molecular weight, degree of polymerization, and syringyl/guaiacyl ratio, reduced the lignin inhibition with a concomitant increase in the hydrolysis of cellulose.
In the present study three biosorbents are prepared from orange peel bio-wastes. These are the raw orange peel (RR), the sodium hydroxide modified orange peel (RN) and the sulfuric acid modified orange peel (RS). The prepared biosorbents are characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), point of zero charge. Batch adsorption method is applied to determine the optimum operational parameters for lead ion removal from aqueous solutions such as pH, initial concentration of metal ion, contact time and adsorbent dosage. Kinetic models have been applied to test the experimental data to determine the mechanism of adsorption and its potential rate-controlling step. The obtained kinetics data revealed that the adsorption process of lead ion is more fitted to pseudo-second order than pseudo-first order. Equilibrium data showed that adsorption of lead ions fitted well with Langmuir equilibrium isotherm model. Thermodynamic parameters Delta G degrees, Delta H degrees and Delta S degrees parameters have been investigated. The negative values of Delta G degrees of all biosorbents explain the spontaneous behavior of adsorption process. The negative values of Delta H degrees can explain the exothermic behavior of (RR, RN), while positive value of Delta H degrees can explain the endothermic behavior of (RS). The prepared orange peel derived biosorbents were successfully applied for removal of lead ion from different water samples.
In the present work, the air-steam biomass gasification model with tar has been developed based on the equilibrium constants. The simulation results based on two different models (with and without tar) have been validated by the experimental data. The model with tar can well predict the tar content in gasification; meanwhile, the predicted gas yield (GY), based on the model with tar, is much closer to the experimental data. The energy exchange between the gasifier and the surrounding has been studied based on the dimensionless heat transfer ratio (DHTR), and the relationship between DHTR and the process parameters is given by a formula. The influence of process parameters on the syngas composition, tar content, GY, lower heating value (LHV), and exergy efficiency have been researched.
The aim of this work was to study the effect of four different types of thermal pretreatment techniques i.e., hot air oven, microwave, autoclave and hot water bath on the hydrolysis, compositional analysis and characterization of water hyacinth. To determine the most efficient thermal pretreatment technique exhibiting enhanced solubilisation. Highest solubilisation was achieved by hot air oven (55.5\%), followed by microwave, hot water bath and autoclave. Bio-chemical methane potential (BMP) test of hot air oven pretreated and untreated water hyacinth was conducted. Cumulative methane production of 3039 +/- 32 mL CH4/g VS was achieved by hot air oven pretreated water hyacinth at 90 degrees C for 1 h which was way higher than the cumulative methane production of untreated water hyacinth 2396 +/- 19 mL CH4/g VS on the 35th day. Compositional analysis and characterization of water hyacinth were also investigated to study the changes in the pretreated samples. (C) 2016 Elsevier Ltd. All rights reserved.
In this work, were studied the thermal and kinetic characteristics of the palm kernel shell (PKS) and empty fruit bunch (EFB) from the African oil palm. Experiments in the inert atmosphere were carried out in a thermogravimetric analyzer. In the kinetic analysis were applied the one-step reaction through iso-conversion methods, mechanism of independent parallel reactions (MIPR), and mechanism of consecutive reactions (MCR). The onestep reaction mechanism overestimated the thermal decomposition of all samples; however, the best was the EFB. The MIPR showed to be representative of the thermal decomposition of all samples, and the proposed correlations between the pre-exponential factor and the heating rate improved the accuracy of the model. The MCR analysis showed that using the same kinetic parameters applied in the MIPR does not affect reliability. Finally, as a conclusion, blending PKS with EFB increase 5\% heating value and decrease 50\% ash content.
Global interest in lignocellulosic biorefineries has increased in the recent past due to technological advancements in sustainable and cost-effective production of numerous commodity and speciality chemicals and fuels from renewable lignocellulosic biomass (LCB). As a result, the market value of biorefinery products has also increased over the time, with an estimated worth of USD 867.7 billion by 2025. However, biorefinery operations, especially enzymatic hydrolysis, suffer from many challenges that limits the cost-effectiveness of conversion of LCB. Therefore, it is essential to understand and address these challenges in future biorefineries. The paper focuses on recent trends and challenges in enzymatic hydrolysis of LCB during lignocellulosic biorefinery operation for greener synthesis of energy, fuels, chemicals and other high-value products. Insights into the gaps in knowledge and technological challenges have also been addressed together with focus on future research needs and per-spectives of enzymatic hydrolysis of LCB for biorefinery applications.
The elution of metallic content from cotton stalk (CS) and its co-pyrolysis with waste tires (WT) was investigated in fixed bed reactor. Hydrochloric acid (HC1) was used for leaching and successful removal of metals from cotton stalk was observed. Removal efficiencies of 86\%, 58\%, 48\%, 58\% and 35\% for potassium, calcium, magnesium, sodium, and iron metals were achieved, respectively. Pyrolysis and copyrolysis using various mixing ratios of raw (R-CS) and acid washed cotton stalk (W-CS) with waste tire were carried out at 550 degrees C. Co-pyrolyzing W-CS with WT not only resulted in increased liquid yield with reduced char and gas yields, but also improved the quality of pyrolytic oil evincing the occurrence of strong positive synergistic effect. The addition of WT reduced oxygenates, density and water content of oil whilst pH and calorific value are increased compared to both, R-CS and W-CS pyrolytic oils. Relative percentage area of hydrocarbons increased to 65\% in co-pyrolysis of WT with W-CS as compared to 47\% for that of R-CS at optimum blend ratio (CS:WT 1:3). Likewise, 19\% higher reduction in oxygenated compounds was observed in W-CS and WT co-pyrolytic oil. Co-pyrolyzing WT with R-CS and W-CS resulted in improved quality of oil. However, the synergistic effect was less significant for R-CS suggesting that the presence of intrinsic metals in R-CS hampered the occurrence of synergistic effects. (C) 2020 Elsevier Ltd. All rights reserved.
Diosgenin is an important raw material for the synthesis of steroid hormone drug and largely required in the pharmaceutical industry. In this study, a novel process for biorefinery of Dioscorea composite Hemsl (DCH) with ferric chloride was developed to investigate the conversion of saponins to diosgenin. Furthermore, the waste, including sugary wastewater and starch residue, as recyclable biomass resources after diosgenin extraction was devoted to biomethane. Consequently, the highest yield of diosgenin (3.02\%) was obtained using ethanol/ water/petroleum ether (15/16/20, v/v/v) with a total volume of 255 mL containing 80 mL 5.0 g/L ferric chloride aqueous solution at 150 degrees C for 2 h. The yield extracted with FeCl3 was 16.6\% higher than the traditional sulfuric acid hydrolysis method and was even 2.3 times more than the biphasic sulfuric acid hydrolysis method. Similarly, without consuming sulfuric acid, the yield was 79.76\% higher than the control method. After fermentation, a maximum biomethane yield of 310.5 mL/g COD (chemical oxygen demand) was achieved from wastewater and the decomposition efficiency reached 91.1\% with an initial COD concentration of 10,800 mg/L decreasing to 960 mg/L. The final biomethane productivity of waste residues was 278.8 mL/g VS and the VS degradation efficiency was 95.8\% after a week. Therefore, the novel method with FeCl3 -catalyzed acidolysis to produce diosgenin and biomethane may be an alternative much cleaner approach to better utilize dioscorea resources.
Renewable energy from lignocellulosic biomass has been deemed an alternative to depleting fossil fuels. In order to improve this technology, we aim to develop robust mathematical models for the enzymatic lignocellulose degradation process. By analyzing 96 groups of previously published and newly obtained lignocellulose saccharification results and fitting them to Weibull distribution, we discovered Weibull statistics can accurately predict lignocellulose saccharification data, regardless of the type of substrates, enzymes and saccharification conditions. A mathematical model for enzymatic lignocellulose degradation was subsequently constructed based on Weibull statistics. Further analysis of the mathematical structure of the model and experimental saccharification data showed the significance of the two parameters in this model. In particular, the. value, defined the characteristic time, represents the overall performance of the saccharification system. This suggestion was further supported by statistical analysis of experimental saccharification data and analysis of the glucose production levels when lambda and n values change. In conclusion, the constructed Weibull statistics-based model can accurately predict lignocellulose hydrolysis behavior and we can use the lambda parameter to assess the overall performance of enzymatic lignocellulose degradation. Advantages and potential applications of the model and the lambda value in saccharification performance assessment were discussed.
Sorption studies of hyper toxic Pb(II) ions from aqueous solution were investigated on simple and urea modified Saccharum bengalense (UMSB) biosorbent. Various experimental parameters including pH, temperature, and contact time were studied to evaluate the adsorption behavior. The equilibrium modeling showed that the biosorption data were better represented by the Langmuir and Freundlich models rather than other studied models. Thermodynamic parameters such as changes in standard free energy (Delta G degrees), standard enthalpy (Delta H degrees), and standard entropy (Delta S degrees) revealed the spontaneous, endothermic, and feasible nature of adsorption process. The biosorption process followed the pseudo-second-order (PSO) model. The intraparticle diffusion model was applied to investigate the rate determining step. The biosorption efficiency of urea modified biosorbent has also been compared with unmodified material. It was found that the sorption capacity (q(m)) increased from 4.73 to 12.65 mg/g on modification. The results of the present investigation suggested that UMSB can be used as an environmentally and economically feasible alternative biosorbent for the removal of Pb(II) from aqueous solutions.
This work deals with the use of vine shoots, a renewable, largely available, lacking of alternatives lignocellulosic material as a feedstock for hydrogen production. Physical pre-treatments by steam explosion (SE), chemical by organosolv (OS) and biological by laccase (LAC) were carried out in vine shoots to disrupt the cell fiber and increase the biomass hydrolysis and fermentation into hydrogen (H-2). After SE, there was a slight decrease in cellulose and hemicellulose contents in biomass fibers, while a decrease in lignin content occurred after OS pretreatment. There were no quantifiable changes after laccase pre-treatment, however the enzyme-substrate oxidative reactions were favorable for hydrolysis and fermentation since an increase in soluble sugars and H-2 production was observed with LAC vine shoots as substrate. 300.1 mL H-2/L were obtained from raw material vine shoots, while 649.4, 399.8 and 749.7 mL H-2/L were obtained from biomass pre-treated by SE, OS and LAC, respectively. Furthermore, the hydrolysis of pre-treated biomass by addition of cellulase was evaluated to improve H-2 production. Higher amounts of H2 were obtained from hydrolyzed biomass in relation to non hydrolyzed ones (154.2\%, 602.0\% and 167.1\% more with SE, OS and LAC hydrolyzed, respectively). In all cases, the mixed acid pathway was carried out by Clostridium butyricum, since acetic and butyric acids were produced.
High-temperature ethanol fermentation by thermotolerant yeast is considered a promising technology for ethanol production, especially in tropical and subtropical regions. In this study, optimization conditions for high-temperature ethanol fermentation of pineapple waste hydrolysate (PWH) using a newly isolated thermotolerant yeast, Saccharomyces cerevisiae HG1.1, and the expression of genes during ethanol fermentation at 40 degrees C were carried out. Three independent variables, including cell concentration, pH, and yeast extract, positively affected ethanol production from PWH at 40 degrees C. The optimum levels of these significant factors evaluated using response surface methodology (RSM) based on central composite design (CCD) were a cell concentration of 8.0 x 10(7) cells/mL, a pH of 5.5, and a yeast extract concentration of 4.95 g/L, yielding a maximum ethanol concentration of 36.85 g/L and productivity of 3.07 g/L. Gene expression analysis during high-temperature ethanol fermentation using RT-qPCR revealed that the acquisition of thermotolerance ability and ethanol fermentation efficiency of S. cerevisiae HG1.1 are associated with genes responsible for growth and ethanol stress, oxidative stress, acetic acid stress, DNA repair, the pyruvate-to-tricarboxylic acid (TCA) pathway, and the pyruvate-to-ethanol pathway.
The recalcitrance in grasses varies according to cell type and tissue. In this study, dilute acid pretreatment was performed on Miscanthus x giganteus internodes that include rind and pith regions which showing heterogeneous structural and chemical changes. Pretreatment on pith effectively hydrolyzed 73.33\% hemicelluloses and separated cohesive cell walls from the compound middle lamella due to lignin migration. Lignin droplets with an average diameter of 49.5 +/- 29.3 nm were concurrently coalesced on wall surface, that in turn exposed more microfibrils deep in walls to be enzymatically hydrolyzed reaching 82.55\%. By contrast, the rind with a relatively intergrated cell structure was covered by larger lignin droplets (101.2 +/- 44.1 nm) and filled with inaccessible microfibrils limiting enzymatic sacchrification (31.50\%). Taken together, the cellulose digestibility of biomass was not majorly influenced by cellulose crystallinity, while it was strongly correlated with the positive effects of hemicelluloses degradation, lignin redistribution, cellulose exposure and loosening cell wall structure. (C) 2016 Elsevier Ltd. All rights reserved.
Cellulose nanocrystals (CNC) were extracted from Miscanthus (MST) fibers using a sulfuric acid hydrolysis process. The results showed that the obtained CNC exhibit a needle-like shape with an average aspect ratio of 37. The surface charge density was measured at 1.99 sulfate groups per 100 anhydroglucose units while the zeta potential value was found to be -38mV. The crystallinity of the extracted CNC was 76\%, and the cellulose I type crystal structure was predominant. Due to its high importance for potential application of CNC in aqueous systems, the rheological behavior of CNC aqueous suspensions at various CNC concentrations was determined. The CNC suspensions showed gel-like behavior at very low CNC concentrations ranging from 0.1 wt\% up to 0.6 wt\%, as confirmed by the steady shear viscosity measurements and the oscillatory dynamic tests. The dynamic rheological parameters of CNC suspensions were slightly affected by the temperature profile. At high temperature up to 80 degrees C a stronger CNC network is formed by increasing the relative motion resistance of CNC macromolecules and the entanglement. In order to identify the reinforcing ability of the newly extracted CNC, starch-based nanocomposite films were produced with various CNC contents (1, 3, 5 and 8wt\%) and their tensile properties were investigated. It was found that the addition 8 wt\% CNC within starch matrix increased the Young's modulus by 150\% and the tensile strength by 118\%, resulting in mechanically strong and eco-friendly nanocomposite materials. {[
Efficient hydrolysis of holocellulose depends on a proper balance between cellulase (endoglucanase, exoglucanase, beta-glucosidase) and xylanase activities. The present study aimed to induce the production of cellulases and xylanases using liquid cultures (one, two, three, and four fungal strains on the same bioreactor) of wild strains of Trichoderma harzianum, Aspergillus niger, and Fusarium oxysporum. The strains were identified by amplification and analysis of the ITS rDNA region and the obtained sequences were deposited in Genbank. Enzymes (endoglucanase, exoglucansae, beta-glucosidase, and xylanase activities) and the profile of extracellular protein isoforms (SDS-PAGE) produced by different fungal combinations (N = 14) were analyzed by Pearson's correlation matrix and principal component analysis (PCA). According to our results, induction of endoglucanase (19.02\%) and beta-glucosidase (6.35\%) were obtained after 4 days when A. niger and F. oxysporum were cocultured. The combination of A. niger-T. harzianum produced higher endoglucanase in a shorter time than monocultures. On the contrary, when more than two strains were cultured in the same reactor, the relationships of competition were established, trending to diminish the amount of enzymes and the extracellular protein isoforms produced. The xylanase production was sensible to stress produced by mixed cultures, decreasing their activity. This is important when the aim is to produce cellulase-free xylanase. In addition, exoglucanase activity did not change in the combinations tested.
Background: Population expansion, global warming, and food scarcity have all increased the demand for alternative lipid sources to ensure food and energy security. Furthermore, over the last few decades, industrialization has posed a significant environmental risk to the world through its waste. Utilization of agri-food waste and byproducts as a substrate by oleaginous microorganisms for production of microbial lipids could be a phenomenal approach. Scope and approach: Oleaginous microorganisms have numerous advantages, including a shorter life span, rapid growth rate, ease of cultivation, ability to use a variety of substrates, and adaptability to metabolic/genetic changes. Exploiting oleaginous microorganisms for the production of microbial lipids can be viewed as an alternative sustainable food source as well as a versatile raw material for the production of food additives, surfactants, and tailored triacylglycerol's. Key Findings and Conclusion: Microbial oil production processes that mimic plant, animal, and marine lipids are non-toxic, sustainable, and adaptable, as well as energy efficient. Recent research on oleaginous microorganisms, as well as recent interventions in waste management, have resulted in microbial oils being the next and most viable product for a variety of end-user applications and an efficient way of waste management.
As green and effective depolymerization processes, CrCl3 and CrCl3-catalyzed ethanol pretreatment were comprehensively investigated to improve cellulose conversion from pretreated residues in poplar in the present study. The influence of pretreatment temperature on delignification, structural characteristics of lignin, and the yield of glucose and ethanol was comparatively analyzed to emphasize the synergy effect of CrCl3 and ethanol solvent. Particularly, CrCl3-catalyzed ethanol pretreatment at 200 degrees C resulted in the pretreated substrates with >94\% removal of hemicellulose and lignin, consequently reaching 88.88\% and 56.11\% yields of glucose and ethanol, respectively. Lignin's structural change was observed by Gel permeation chromatography and 2D nuclear magnetic resonance spectroscopy and its relationship with the efficiency of enzymatic hydrolysis and fermentation was determined. Results indicated that the increased pretreatment temperature enhanced the lignin depolymerization with smaller molecular weight, fewer beta-O-4 linkages, and higher S/G ratio, especially in CrCl3-catalyzed ethanol pretreatment, which was positively associated with poplar cellulose conversion. In addition to offering a comprehensive illustration of the sugar/ethanol generation during CrCl3-catalyzed organosolv pretreatment, this work also provided theoretical support for biofuel and biochemical production from poplar.
Mesta crop biomass is one of the unexplored lignocellulosic feedstocks for second-generation bioethanol production. The compositional analysis of two mesta species, namely Hibiscus sabdariffa and H. cannabinus were carried out which revealed that the mesta contains 41.89-46.50\% cellulose that can be saccharified to release fermentative sugar. Among different physical and physico-chemical pretreatment methods employed, cold alkali (2\%) treatment showed maximum cellulose enrichment (38.71\%) and significant lignin removal (27.27\% of total). Optimization of saccharification process for pretreated mesta biomass was carried out using Box-Behnken design. Based on the observations, use of 4.02\% substrate loading, 15.02 FPU/mL of cellulase from psychrotolerant Aspergillus niger SH3, and 5.01 IU/gds of beta-glucosidase from Pseudomonas lutea BG8, led to 533.25 mg/gds sugar release from the pretreated biomass. Simultaneous saccharification and fermentation was carried out using efficient thermotolerant yeast strain Saccharomyces cerevisiae LN that resulted in 4.1 g/L ethanol production. It can be concluded that mesta crop can be a good source for the production of second-generation biofuel and the ethanol yield can be further improved by use of accessory enzymes and co-fermenting yeast.
Sunn hemp fibre - a cellulose-rich crystalline non-food energy crop, containing 75.6\% cellulose, 10.05\% hemicellulose, 10.32\% lignin, with high crystallinity (80.17\%) and degree of polymerization (650) - is identified as a new non-food substrate for lignocellulosic biofuel production. Microwave irradiation is employed to rapidly rupture the cellulose's glycosidic bonds and enhance glucose yield to 78.7\% at 160 degrees C in only 46 min. The reactants - long-chain cellulose, ionic liquid, transition metal catalyst, and water - form a polar supramolecular complex that rotates under the microwave's alternating polarity and rapidly dissipates the electromagnetic energy through molecular collisions, thus accelerating glycosidic bond breakage. In 46 min, 1 kg of Sunn hemp fibres containing 756 g of cellulose produces 595 g of glucose at 160 degrees C, and 203 g of hydroxymethyl furfural (furanic biofuel precursor) at 180 degrees C. Yeast mediated glucose fermentation produces 75.6\% bioethanol yield at 30 degrees C, and the ionic liquid is recycled for cost-effectiveness.
MSW compost valorization under combustion, at two different composting process conditions, have been studied by thermogravimetric analysis (TGA). The composting operating parameters such as aeration and moisture affect the biodegradability of compost and results of the combustion (different gross heating values for each reactors). The obtained TGA showed that maximum weight loss for 10-12\% (245-247 degrees C), 32-34\% (407-411 degrees C) and 44-46\% (760-769 degrees C) in correspondence to hemicellulose, cellulose and lignin-humic-fulvic acids decomposition for each reactor are observed. Obtained valued in kinetic study (Flynn-Wall-Ozawa method) results in suitable coefficients of determination. In that form, to establish the assumption that combustion of compost under a first-order reaction may be appropriate. Moreover, in both reactors, the conversion rate increased and the activation energy decreased with composting time is found. The maximum gross heating value versus minimum activation energy (for alpha = 0.25 and alpha -= 0.5) corresponds to final composts and under aeration of 0.050 and 0.175 L-air kg(-1) d(-1) and moisture of 40\% and 55\% for R1 and R2 reactors respectively. For MSW, under proper conditions, composting could be used as a suitable biodrying process, stabilizing and concentrating the heating value.
Ozonolysis is potentially an effective method for pretreating lignocellulosic biomass to improve the production of fermentable sugars via enzymatic hydrolysis. The eliminated branches from eucalyptus trees can represent a production of around 30 million m(3) of lignocellulosic material annually only in Brazil. Attempts of developing strategies for a rational use of this biomass are, thus, welcome. In this study, Eucalyptus grandis branches were pretreated with ozone in an attempt to increase enzymatic saccharification. Ozonolysis resulted in the degradation of lignin with negligible losses of cellulose and small losses of hemicellulose. Reduction in the lignin content from 26.63 to 9.53\% already resulted in the maximal improvement of the saccharification yield (from 20 to 68\%). The results indicate that ozone pretreatment can be a promising way of increasing the enzymatic digestibility of eucalyptus sawdust from eliminated branches of trees for its conversion into fermentable sugars.
Cellulose nanocrystal (CNC) composite coatings may impart many benefits in packaging, electronic, optical, etc. applications, however, large-scale cellulose coating production is a major engineering challenge. A versatile roll-to-roll reverse gravure process for the manufacture of cellulose nanocrystal-poly(vinyl alcohol) (CNC-PVA) coatings on a flexible polymer substrate was investigated in the present work. CNC content was varied from 0 to 100\% to determine the effect of CNC concentration on coating anisotropy. Coatings were characterized by polarized light microscopy, UV-Vis spectrophotometry, cross-hatch adhesion testing and optical profilometry. This method produced uniform, highly transparent coatings with surface roughness less than 100nm for all CNC-PVA weight ratios examined. The isotropic-anisotropic coating transformation was observed above 50\% CNC, with a maximum anisotropy at 70\% CNC along the shear direction. Anisotropic CNC-PVA coatings exhibited increased water vapor barrier performance due to the increased CNC packing and density.
The pretreatment of Miscanthus x giganteus with the ionic liquid 1-ethyl-3-methylimidazolium acetate ({[
Burnt clay brick is one of the oldest and most widely used construction materials. The production of burnt clay bricks with various waste materials can help reduce the environmental hazards and improve brick performance at low manufacturing costs, thereby leading towards more sustainable construction. This research aimed to evaluate the effect of using waste marble powder (WMP) in varying percentages, i.e., 0, 3, 6, 9, 12, and 15\%, by weight of clay in an industrial brick kiln plant. A range of mechanical and durability tests was performed on the raw material, i.e., clay, WMP, and bricks, to quantify their performance. It was observed that incorporation of WMP resulted in a reduced unit weight of the bricks, making the structure lighter in weight. Moreover, compressive strength and freeze thaw test results for all the brick specimens and sulfate tests for the brick specimens with 12\% WMP addition were within the Building Code of Pakistan, and ASTM C67 prescribed limits. Finally, it can be concluded that WMP up to 12\% by weight of clay can be incorporated to prepare burnt clay bricks, which can reduce the environmental waste to achieve sustainability and economy for the brick industry.
Microbial proteases are commonly produced by submerged (SmF) or solid-state fermentation (SSF), whose combination results in an unconventional method, called sequential fermentation (SF), which has already been used only to produce cellulolytic enzymes. In this context, the aim of the present study was the development of a novel SF method for protease production using wheat bran as a substrate. Moreover, the kinetic and thermodynamic parameters of azocasein hydrolysis were estimated, thus providing a greater understanding of the catalytic reaction. In SF, an approximately 9-fold increase in protease activity was observed compared to the conventional SmF method. Optimization of glucose concentration and medium volume by statistical means allowed us to achieve a maximum protease activity of 180.17 U mL(-1). The obtained enzyme had an optimum pH and temperature of 7.0 and 50 degrees C, respectively. Kinetic and thermodynamic parameters highlighted that such a neutral protease is satisfactorily thermostable at 50 degrees C, a temperature commonly used in many applications in the food industry. The results obtained suggested not only that SF could be a promising alternative to produce proteases, but also that it could be adapted to produce several other enzymes.
The valorization of a South African paper mill waste sludge into an activated biocarbon electrode material for energy storage application is reported. The valorization method is a two-step synthesis that comprises hydrothermal carbonization and NaOH activation of paper mill waste at 700 degrees C to produce activated biocarbon. The development of high porosity carbon material with a surface area of 1139 m2/g was observed. The synthesized biocarbon electrode exhibited good specific capaci-tance (Csp) values of 206 and 157 Fg-1, from a three-electrode cell in neutral (1 M Na2SO4) and alkali (3 M KOH) electrolytes, respectively. The electrolyte concentration purportedly has a considerable effect on specific capacitance. In both electrolytes, symmetric triangular curves in galvanostatic charge-discharge point to a quick charge-discharge process. Synthesized material testing with a two-electrode cell in 3 M KOH and 1 M Na2SO4 electrolytes, respectively, delivered specific capacitances of 125 and 152 Fg-1, with the corresponding energy densities of 17.4 and 21.1 Wh kg-1. The material had capacity retention efficiencies of 83 and 92\% after 5000 cycles in 3 M KOH and 1 M Na2SO4 electrolytes, respectively. The electrode material performance of the activated biocarbon from paper sludge clearly shows its potential for electrochemical energy storage. The reported results present an exciting potential contribution of the pulp and paper industry toward the transition to green energy.
This study reports the utilization of raw agricultural biowaste groundnut shell (GS) as a potential immobilization matrix for an isolated bacterial consortium as a sustainable means to remove 4-nitrophenol (4-NP). Optimization of five parameters such as immobilization matrix size, matrix dosage, pH, temperature, and agitation and their three levels was done through Taguchi Orthogonal Array approach by Qualitek-4 software. Taguchi methodology indicated the optimum reaction conditions to be (in order of their significance) agitation speed (100 rpm), immobilization matrix dosage (4 g), matrix size (800 mu m), pH (9), and temperature (32 degrees C), resulting in an overall enhancement of 57.30\% 4-NP removal efficiency under the optimized conditions. GS-immobilized cells exhibited an improved substrate removal efficiency and high substrate tolerance over free cells, indicating the synergistic effects of adsorption and biodegradation on the removal process. The GS immobilized cells could remove 1000 mg l(-1) of 4-NP as opposed to only 700 mg l(-1) by the free cells. Biodegradation kinetics were analyzed using various substrate inhibition models, and Haldane model fitted the experimental data reasonably well. GS immobilized cells retained a stable activity of 85.5 +/- 3.48\% for 45 days when stored at 4 degrees C and could be efficiently reused for 4 consecutive cycles. Thus, utilizing untreated agricultural wastes like GS will be a cost-effective alternative to conventional immobilization matrices in small-scale industries and can be a step towards sustainable agro-waste management and contaminated wastewater treatment.
Composites with high content of rice husk (80\% based on the solids weight) without and with PLA (5\%) and PBAT (2.5\%) coating were produced and characterized. Thickness, morphology, thermal and mechanical properties, water absorption capacity and hydrophilicity were evaluated. The optical microscopy indicated a more uniform surface after double coating with PLA that was confirmed by the iodine test. The modulus of elasticity and deflection were not influenced by the thin layer of PLA. On the other hand, water absorption capacity decreased with both polymers used as coating, but lower values were reached with PLA. All materials presented hydrophobic character (contact angle higher than 90 degrees) when measured instantly, with a small decreased after 5 min. The samples coated only once with PLA or PBAT showed analogous thermograms to the uncoated composite.
Polyvinyl alcohol (PVA) films containing seaweed extracted cellulose nanocrystal (CNC) (5\% w/v) and 5, 10, and 20\% (w/v) basil leaves extract (BE) were prepared using the solvent casting method, and their physical properties, and antimicrobial and antioxidant activity were analyzed. The addition of 5\% (w/v) CNC to PVA improved the tensile strength and water vapor permeability. Addition of BE to film the antioxidant activity and antimicrobial properties of the films were enhanced. Further, increasing the amount of BE slightly affected the color of the bio-nanocomposites. The thermal stability of films was improved with addition of CNC. Due to functional groups and linkage properties of the CNC surface and macromolecular chains of the PVA were responsible for improvement of the interfacial interactions between the CNC and PVA. The dispersion of CNC in PVA were affected with increase in the amount of BE in PVA. This study showed the benefits of the incorporation of CNC and BE into PVA films and the potential for their use as active packaging material for food. (C) 2017 Elsevier B.V. All rights reserved.
A combinatorial pretreatment process with liquid hot water (LHW) and sodium hydroxide were explored to compare the potential impact of each pretreatment on ethanol production from poplar. The physicochemical properties and ultrastructure of substrates before and after pretreatment were characterized to highlight their impacts on subsequent simultaneous saccharification and fermentation (SSF). The results revealed that 200 degrees C LHW combinatorial 1\% NaOH pretreatment achieved the highest ethanol yield of 50.90\% with 22.71 g/L of ethanol concentration, which was strongly correlated with the removal of hemicellulose and delignification. Then, the key factors related to biomass recalcitrance, such as cellulose crystallinity index (CrI), accessibility and degree of polymerization (DP) were analyzed by X-ray diffraction (XRD), Simons' staining and Gel Permeation Chromatography (GPC) method, respectively. After pretreatment, an increased cellulose CrI/accessibility and decreased cellulose DP were obtained in pretreated poplar, which could effectively improve the subsequent fermentation yield, and in this study, hemicellulose/lignin removal and cellulose accessibility exhibited positive correlation with the adsorption capability of cellulase, whereas, cellulose DP were negatively potential associated with SSF. This work will provide important guidance for better understanding the influences of biomass recal-citrance on ethanol production during the pretreatment process.
Lupin is among the most promising plant-based food protein sources due to its high protein and fibre content. The fibre fraction, especially from seed coats, is often seen as low in value (discarded as waste or as animal feed) and greater knowledge on its composition and structure are crucial to increase its usefulness. However, only one model of lupin fibre structure exists in the literature. Our sample of Finnish-grown narrow-leafed lupin seed consisted of fibre (43.3\%), protein (31.3\%), fat (8.1\%) and starch (0.2\%). According to the sugar analysis, rhamnogalacturonan-I, with branches of arabinan and galactan, constituted the main pectin population in the fibre fraction. A revised model of the overall fibre structure is proposed. At concentrations of 0.75\% and 1.0\%, both unrefined and defatted flour of whole lupin seeds produced stable suspensions and oil-in-water emulsions, demonstrating their application as potential emulsifiers. This study presents the knowledge and opportunity to support sustainability through the utilization of whole lupin seed for future industrial applications.
The large amount of residues generated by the peach palm agroindustry and its cellulose content (34 g 100g(-1)) motivated the present investigation, where outer sheaths were used for nanocellulose production through ultrafine grinding. Protocols combining different chemical delignification with defibrillation intensity (10 and 20 cycles) were applied and their influence over some properties and characteristics of nanofibers evaluated. At all protocols applied it was possible produce cellulose at nanometric level (widths (similar to)100 nm), with high crystallinity index (49.8-54.5\%) and great thermal stability. The delignification influenced the defibrillation, where lignin removal resulted in well dispersed bundles of fibrils with lower widths. Lower lignin contents combined with higher shear forces released more nanofibrils, with more adsorbed water with defibrillation extension. These behavior influenced the suspension stability, that was higher at larger number of cycles (20). The results evidenced that was possible produced FNC with appropriate technical characteristics from pupunha discards.
Foams from thermoplastic starch (TPS) are interesting options to replace single-use packaging made with nonbiodegradable polymers derived from fossil fuels. These foams are made with materials from renewable and biodegradable sources, which do not harm the environment. However, this material has poor mechanical properties and breaks easily when handled. Adding natural fibers, such as cotton, is an easy option that can generate foams that are more resistant to impact and handling. In this work, the incorporation of cotton fibers into starch foams was studied. Two types of fiber were used: cotton fiber and cotton microfiber. In addition, three fiber contents were evaluated: 0.67\%, 2.00\% and 3.33\%. The results showed that both cotton types showed great compatibility and homogeneity with starch and both significantly improved the mechanical properties of the foams. Foams with a greater amount of cotton fibers (2.00\% and 3.33\%) showed the best results for impact and tensile tests.
Thermal behavior and chemical properties of selected raw and NaOH-pretreated rice husk varieties were investigated. NaOH-pretreatment process involved soaking 5 g rice husk samples in 40 mL of 2\%w/v NaOH, shaking (400 rpm) and heating (50 degrees C) for 3 h. NaOH-pretreated samples were water-washed, oven-dried, and milled for use in the determination of their thermal behavior and surface functional groups. Alkaline wash-water was also analyzed for sugar components. Thermal decomposition temperatures, degradation rates, and the subsequent mass losses varied from one rice husk variety to another. These thermal properties increased after NaOH-pretreatment of the rice husk varieties, reducing their char yields (17.1-20.4\% db). These changes mainly had to do with the lignin, hemicellulose, and ash removal from the rice husk varieties, as confirmed by their FTIR analysis, as well as by the sugar composition analysis of their alkaline wash-water. Consequently, the FTIR spectra differed between the raw and NaOH-pretreated rice husk varieties.
Eucalyptus sawdust is a residue from the pulp and timber industries which can be used as a raw material in a biorefinery. In this work, two consecutive treatment steps were applied to eucalyptus sawdust from a pulp mill, as a fractionation strategy, to recover and preserve lignocellulosic components while enhancing enzyme accessibility to cellulose. The first treatment step assayed was autohydrolysis (170 degrees C, 40min). It was followed by (a) mechanical refining (3000rpm, 0.5mm), (b) kraft pulping (155 degrees C, 90-140min, alkali charge 2.1-3.4\%), or (c) soda pulping (155 degrees C, 90min, alkali charge 2.4-4.0\% NaOH). The remaining solid fractions were enzymatically hydrolyzed using 25FPU/g of Cellic CTec 2 from Novozymes and a solid content of 13\%. The efficiency of the enzymatic hydrolysis was higher than 70\% in the case of an additional kraft or soda pulping while only autohydrolysis led to efficiencies lower than 60\%. The best hydrolysis parameters and lignin and xylose recovery yields were obtained for autohydrolysis followed for a kraft pulping (cellulose conversion up to 71\%, cellulose hydrolysis 95\% at 48h, lignin and xylose recovery 99 and 85\%, respectively). The treated solid that reached the highest enzymatic yields was fermented using Saccharomyces cerevisiae in a 3.5-L reactor. The highest bioethanol yield was found for the autohydrolysis-treated solids followed by soda pulping, reaching a value of 250L of ethanol per tonne of sawdust. Under this condition of combined treatments, 300kg lignin/t (sawdust) and 120kg xylose/t (sawdust) can be obtained.
Hydrogen production from enzymatic hydrolysates of Agave lechuguilla pretreated by autohydrolysis was assessed in this work. The pretreatment was carried out in a high-pressure reactor using a solid/liquid ratio of 1:6 (w/v) at 190 degrees C for 30 min at 200 rpm. The pretreated solids were enzymatically hydrolyzed and then were digested with a treated mixed consortium under specified conditions with a Taguchi (L-9(3(4))) experimental array. The results showed that the xylan was 65.2\% solubilized during pretreatment, and the glucan preserved was 77.5\% hydrolyzed, obtaining a hydrolysate with 55 g/L of glucose. The production of hydrogen after anaerobic digestion of hydrolysates was significantly influenced mainly by the temperature (80.6\%) and glucose concentration (15.1\%). The best conditions were 40 degrees C, glucose 20 g/L, inoculum 5\% (v/v), and initial pH 7. Under optimal conditions, the hydrogen yield achieved was 3.48 mol H-2/mol glucose consumed at 120 h.
Biodiesel wastewater generally contains high levels of oils, soaps and glycerol residues. This needs wastewater treatment. In this study, the biodiesel wastewater treatment was tested (industrial wastewater (EFID) and laboratory wastewater (EFLB) from biodiesel) by performing flocculation and dual-flocculation with renewable polymers. Tannin and cationic hemicellulose (CH) were used as cationic flocculant, and cellulose acetate sulfate (CAS) was used as an anionic flocculant. Polyacrylamide (PAM) was used as a reference anionic flocculant for result efficiencies analysis obtained with CAS (renewable source flocculant). The treatment efficacy in wastewater was evaluated by: turbidity removal, sludge volume formed, chemical oxygen demand (COD) and total suspended solids (TSS). The obtained sludge was studied using thermogravimetric analysis (TG). The dual-flocculation application condition of the 25\% proportion of tannin (T) and 75\% proportion of cationic hemicelluloses (i.e., T25/ CH75) showed EFLB turbidity removal of 89.1\% and 89.5\% for CAS and PAM additions respectively, and for EFID of 67\% and 41\% for CAS and PAM additions respectively. The dual- flocculation performance suggested that the polyelectrolytes obtained from renewable sources can be used for treating biodiesel wastewater.
Technical alkaline lignin was first pretreated with alkaline hydrogen peroxide and then liquefied using methanol-water mixture or methanol solvents. When the technical lignin was pretreated by 0.5\% H2O2 at 80 C, the liquid yield of the liquefaction in methanol-water mixture and methanol increased from 84.2\% to 93.5\% and from 79.2\% to 90.5\%, respectively. The alkaline lignin (AL), pretreated lignin (PL) and resulting liquid (RL) were characterized by using GPC, FT-IR, and H-1 NMR methods. The GPC results illustrated that the pretreatment by 0.5\% H2O2 could decrease the weight average (Mw) and number average (Mn) molecular weight from 1692 to 1354 g/mol and from 1376 to 1207 g/mol, respectively. The FT-IR and 1H NMR results confirmed that some phenols were oxidized to quinone or aliphatic chain structures, and parts of side chains were separated from lignin. (C) 2016 Elsevier B.V. All rights reserved.
The impacts of ionic liquid and alkaline pretreatments on the enzymatic hydrolysis and thermal degradation of corn stover were investigated to better understand the mechanism of biomass pretreatment. Corn stover samples were pretreated at a 5 wt\% biomass loading in 1-butyl-3-methylimidazolium acetate ({[
This work describes the application of two forms of heating for autohydrolysis pretreatment on isothermal regimen: conduction-convection heating and microwave heating processing using corn stover as raw material for bioethanol production. Pretreatments were performed using different operational conditions: residence time (10-50 min) and temperature (160-200 degrees C) for both pretreatments. Subsequently, the susceptibility of pretreated solids was studied using low enzyme loads, and high substrate loads. The highest conversion was 95.1\% for microwave pretreated solids. Also solids pretreated by microwave heating processing showed better ethanol conversion in simultaneous saccharification and fermentation process (92\% corresponding to 33.8 g/L). Therefore, microwave heating processing is a promising technology in the pretreatment of lignocellulosic materials. (C) 2017 Elsevier Ltd. All rights reserved.
The production of cellulosic ethanol from biomass is considered as a promising alternative to fossil fuels, providing a sustainable option for fuels production in an environmentally compatible manner. The presence of lignin poses a significant challenge for obtaining biofuels and bioproducts from biomass. Part of that problem involves understanding fundamental aspects of lignin structure which can provide a pathway for the development of improved technologies for biomass conversion. Hydrotropic pretreatment has several attractive features that make it an attractive alternative for biofuel production. This review highlights the recent developments on hydrotropic pretreatment processes for lignocellulosic biomass on a molecular structure basis for recalcitrance, with emphasis on lignin concerning chemical structure, transformation and recalcitrance. The review also evaluates the hydrotropic delignification in comparison to alkaline delignification on lignin reduction and surface coverage by lignin. The effect of hydrotrope pretreatment on enzymatic saccharification has also been discussed. (C) 2016 Elsevier Ltd. All rights reserved.
The alarming rate of population growth has increased the demand for food production in third-world countries leading to a yawning gap in demand and supply. This has led to an increase in the number of hungry and chronically malnourished people. This situation has created a demand for the formulation of innovative and alternative proteinaceous food sources. Single cell protein (SCP) production is a major step in this direction. SCP is the protein extracted from cultivated microbial biomass. It can be used for protein supplementation of a staple diet by replacing costly conventional sources like soymeal and fishmeal to alleviate the problem of protein scarcity. Moreover, bioconversion of agricultural and industrial wastes to protein-rich food and fodder stocks has an additional benefit of making the final product cheaper. This would also offset the negative cost value of wastes used as substrate to yield SCP. Further, it would make food production less dependent upon land and relieve the pressure on agriculture. This article reviews diversified aspects of SCP as an alternative protein-supplementing source, Various potential strains and substrates that could be utilized for SCP production are described. Nutritive value and removal of nucleic acids and toxins from SCP as a protein-supplementing source are discussed. New processes need to be exploited to improve yield. In that direction the solid state fermentation (SSF) method and its advantages for SCP production are highlighted. (C) 2000 Elsevier Science Inc. All rights reserved.
A novel type of emulsifiers (STOC-SAC0, SAC8 \& SAC12) were synthesized from nature-abundant cellulose by a two-step process: preparartion of soluble cellulose by TEMPO-mediated oxidation of cellulosic nanocrystal and fractionation (STOC), and introduction of hydrophobic moiety by alkyl (C0, C8 \& C12)succinylation of resulting soluble polysaccharides. The synthetic products were structurally verified by Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) and Gel Permeation Chromatography (GPC). The surface-active property and functionality of the new ingredients were characterized by determinations of contact angle, ABTS radical scavenging and Ferrous chelating ability, and their performance as new ingredient; which demonstrated that alkylsuccinylated soluble TEMPO-oxidized celluloses (STOC-SACx) have unique multi-purpose functionalities: emulsifying, stabilizing and antioxidant property. STOC-SAC12 displayed the best surface activity with the lowest contact angle (18 degrees on a hydrophobic surface basis) and the highest antioxidant properties (compared to succinylated cellulose (C-SAC0) the ABTS radical scavenging and Fe2+ chelating property of STOC-SAC12 are significantly higher by 10-fold and 4.5-fold, respectively); accordingly STOC-SAC12 also resulted in the most stable homogeneous fish oil-in-water nanoemulsion with a mean droplet size of 200 nm, polydispersity index of 0.18 and zeta-potential up to-90 mV; evidenced by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLFM) and dynamic light scattering analyses. In short this work reported a industry -feasible and fully scalable approach to transform abundant renewable plant cellulose into novel ingredients with unique fucntionalities which could find potential application in delivery of oxidation-prone bioactives through complicated emulsion systems.
Rapid population and economic growth, excessive use of fossil fuels, and climate change have contributed to a serious turn towards environmental management and sustainability. The agricultural sector is a big contributor to (lignocellulosic) waste, which accumulates in landfills and ultimately gets burned, polluting the environment. In response to the current climate-change crisis, policymakers and researchers are, respectively, encouraging and seeking ways of creating value-added products from generated waste. Recently, agricultural waste has been regularly appearing in articles communicating the production of a range of carbon and polymeric materials worldwide. The extraction of cellulose nanocrystals (CNCs) and carbon quantum dots (CQDs) from biomass waste partially occupies some of the waste-recycling and management space. Further, the new materials generated from this waste promise to be effective and competitive in emerging markets. This short review summarizes recent work in the area of CNCs and CQDs synthesised from biomass waste. Synthesis methods, properties, and prospective application of these materials are summarized. Current challenges and the benefits of using biomass waste are also discussed.
Food processing industries produce a huge amount of heterogeneous by-products in different processing operations while converting raw materials into final products. The extraction-based value addition of these byproducts is an important step for waste minimization. In this context, it is desirable to approach greener extraction alternatives using smart solvents like ionic liquids and deep eutectic solvents. These solvents may potentially replace conventional solvents due to their biocompatibility, low toxicity and recyclability. Also, these solvents have tunable properties needed for specific selectivity of a particular bioactive compound. This paper delivers information regarding different types of neoteric solvents (fluomus solvents, ionic liquids and deep eutectic solvents) and their application in the extraction of high-value compounds from food processing byproducts.
In this study, crude and partially purified xylanase from Aureobasidium pullulans CCT 1261 were characterized and applied in beechwood xylan hydrolysis to obtain xylooligosaccharides (XOS). Fractional precipitation (0?30 \%/30?60 \%) with ammonium sulfate allowed partial purification of xylanases in 6.8-fold and recovery of 69.4 \%. Both extracts exhibited optimum activity at 50 ?C and pH 4.5, and greater stability at 40 ?C within the studied range. The thermostability parameters (kd, t1/2, ?H{*
This research demonstrates the feasibility and efficacy of removing heavy metals from aqueous solutions using waste banana and orange peels. The fruit peels are carbonised, without the addition of chemical substances, to enhance their adsorption capacities. The adsorption capacities are studied in aquatic solutions containing individual and combined metal ions of hexavalent chromium (Cr6+), copper (Cu) and zinc (Zn). The selectivity of the adsorbents towards these metal ions is also exhibited. The results show that both fruit peels exhibit a better selectivity towards zinc ions, followed by copper and then hexavalent chromium. The effects of operational conditions, including pH, adsorbent dosage, contact time and concentration of metal ions, on the removal efficiency and uptake capacity of the carbonised fruit peels are investigated. The optimal adsorption for both adsorbents occurs within 30 min of exposure and at an adsorbent dose of 0.5 g. Additionally, the adsorption kinetics and isotherms, including pseudo-second-order, Langmuir and Freundlich, are modelled for the obtained data.
The influence of lignin content on reclaimed rubber (RR)/natural rubber (NR) blend composite properties has successfully been studied. Scanning electron microscopy (SEM) were used to understand morphology. Fourier-transform infrared spectroscopy (FTIR) for the possible chemical interaction, whereas thermogravimetric analysis (TGA) and tensile tester were used to predict strength and elongation for possible practical applications. The results indicated that the presence of lignin forms cavities which seemed to arise from complex interactions of the blend with the lignin. Those cavities dominated tensile fractured surface and the increase in lignin indicated inconsistencies of interfacial interactions. Lignin RR/NR blend composites revealed a drop in tensile strength and shift in glass transition temperature, except for the highest lignin containing blend composite. More active interactive constituent of the blend appeared to be NR. The interaction has not favored the thermal stability and crosslinking density.
The effect of polylactic acid (PLA), cellulose microfibers (CEL), and calcium carbonate (CaCO3) on the equilibrium moisture content (EMC), density and flexural mechanical properties of starch-based bio-foams was studied using a full factorial design 2(3). Also, a moisture aging study was carried out. The results show the three factors studied changed the bio-foams morphology, contribute to density increment, enhance dimensional stability and improve both the moisture resistance and the mechanical flexural properties. The moisture aging studies show that, although the flexural mechanical properties decrease with increasing humidity, the bio-foams exceed the mechanical properties of commercial expanded polystyrene (EPS) trays. These findings suggest the bio-composites could be used in regions where the humidity conditions are moderate to very humid, guaranteeing their dimensional stability and functional properties. Thus, these new bio-foams are an attractive and sustainable option to replace the non-biodegradable EPS commercial trays.
The objective of this study was to evaluate the effect of hydrotropic delignification of cotton stalk on sugar release performance for bioethanol production. In this study, different alkyl benzene sulfonates were screened to select the best pretreatment agent, and the effectiveness of pretreatment was evaluated by enzymatic saccharification. Sodium cumene sulfonate was found to be the best hydrotropic agent in terms of reducing sugar yield. Parameters such as hydrotrope concentration, biomass loading and incubation time were optimized by adopting a central composite design. Under optimized pretreatment conditions, 0.211 g reducing sugar/g of dry biomass was obtained. Reusability of aqueous hydrotrope solution was also demonstrated.
Biofuels production is a fast growing and emerging industry. Occupational injuries are a serious problem due to their human, financial and social costs, yet little research has been published on injuries in the biofuels industry. Learning from past injuries are essential for preventing future occurrences, but the lack of injury information hinders this effort in the biofuels industry. The present study addresses this knowledge gap by utilizing data from over 900 workers' compensation claims reported from 2008 to 2016 by ethanol and biodiesel facilities in the U.S. to characterize injury costs and severity. The total amount paid for each claim was used as a measure of injury severity, and the effects of age, tenure, type of claim, body part injured, nature and, cause of injury on the cost of work-related injuries were investigated. Contingency tables were used to classify the variable pairs, chi-square test and chi-square residuals were employed to evaluate the relation between the variable pairs and identify the at-risk groups. Results showed age, tenure of employee, type of claim, body part injured, nature of injury and, cause of injury have a significant influence in determining the claim amount. Age group 46-50, tenure group 1-2 years, strain and fractures injuries, slips, falls, or trips and, injuries to lower extremities were some of the at risk groups identified. The findings from the study will assist biofuel producers to develop precisely targeted safety interventions that are effective in preventing worker injuries and also mitigating the financial and social losses from occupational injuries.
Elephant grass is gaining attention among lignocellulosic materials due to its high growth potential, biomass yield, limited requirement for cultivation land and high rates of carbon dioxide absorption. Here was investigate the effect of pretreatment with different concentrations (5, 10 and 20\%, mass acid/mass material) of diluted sulfuric acid on the whole elephant grass plant compared with its leaf and stem fractions. The stem was the most recalcitrant fraction, judging from the high recovery of water insoluble solids (WIS) and lower enzymatic hydrolysis yield, upon acid pretreatment. In enzymatic hydrolysis assays, the glucose yield increased with increasing concentrations of acid, reaching maximum values of 89.20 (leaf), 43.54 (stem) and 76.01\% (whole plant). The crystallinity index (CrI) increased in both elephant grass fractions, which correlated with the solubilization of amorphous materials such as hemicellulose. Also, the stem fraction had a slightly higher heating value than the leaf fraction (3958.45 and 3939.49 cal/g, respectively). Scanning electron microscopy (SEM) analysis showed drastic morphological changes in the samples with increasing pretreatment severity, although the stem fraction suffered less structural damage than other materials. Taken together, the results suggest that the separation of elephant grass in different fractions decreases biomass heterogeneity and generates a fraction (leaf) with lower inherent recalcitrance and, thus, higher susceptibility to pretreatment and enzymatic hydrolysis, increasing the efficiency of fermentable sugar release. The results indicate that the leaf fraction of elephant grass has higher potential for use in second-generation ethanol production, while the stem fraction may be more useful for energy co-generation by combustion.
High-molecular weight lignins (HML) and low-molecular weight lignins (LML) were extracted from flax shives using pressurized 30\% aqueous ethanol, and isolated by precipitation and ultrafiltration. The isolated lignin samples and two commercial lignins were assayed for monolignol content and functional groups, solubility assays, thermal analysis using differential scanning calorimetry (DSC), size exclusion chromatography (SEC), and Fourier transform infrared spectroscopy (FT-IR). The highest yield of HML was 13.5 g/100 g of flax shives, and this was about six times higher than the LML yield. SEC of lignin samples revealed that the molecular weights of HML and LML are about 30,000 and 8749 Da, respectively. The DSC results of HML show that this lignin has a glass transition temperature near 160 degrees C. HML contains fewer carboxyl groups and more phenolic hydroxyl groups than LML. The higher molecular weight and higher thermal stability of HML makes it an excellent candidate for industrial applications. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.
The feasibility and performance of hydrogen production from paper sludge without inoculation was investigated under thermophilic conditions. The maximum hydrogen production reached 64.32 mM with 7.4\% PS. The dynamic changes in bacterial community structures during hydrogen production were investigated by analyzing 16S rDNA gene sequences using high throughput sequencing technology. The results showed that microbial community was dominated by order Clostridiales and Thermoanaerobacterales. Genus Thermoanaerobacterium and Ruminiclostridium played a leading role in the fermentation process, which was responsible for the hydrolysis of PS and hydrogen production. Effect of inoculation with Clostridium thermocellum on hydrogen production from PS was also studied. The results showed that C. thermocellum supplement significantly increased hydrogen yield and holocellulose degradation rate by 96.80\% and 32.95\%, respectively. In addition, inoculation of C. thermocellum enhanced VFA generation and shortened the lag phase of hydrogen production. The present study lays the foundation on the valorization of waste lignocellulose.
With the development of society, the demand for cement-based composites is increasing day by day. Cement production significantly increases CO2 emissions. These emissions are reduced when high volumes of cement are replaced. The consideration of sustainable development has prompted people to search for new cement substitutes. The lignocellulosic biomass ash obtained from burning lignocellulosic biomass contains a large number of active oxides. If lignocellulosic biomass ash is used as a partial cement substitute, it can effectively solve the high emissions problem of cement-based composites. This review summarizes the physicochemical properties of lignocellulosic biomass ashes and discusses their effects on the workability, mechanical properties, and durability (water absorption, acid resistance, etc.) of cement-based composites. It is found that appropriate treatments on lignocellulosic biomass ashes are beneficial to their application in cement-based composites. Meanwhile, the issues with their application are also pointed out.
Optimum conditions for xylitol production from xylose based on the reliable kinetic models of the fermentative performance are important to design lignocellulosic xylitol production. The model was validated by comparing the simulation results with experimental data in batch culture of Kluyveromyces marxianus ATCC 36,907 under various concentrations of initial substrate (36 to 122 g/L) and agitation speed of the impeller (200 to 500 rpm) in a 3.6-L bioreactor. The model suggested that the kinetics of K. marxianus ATCC 36,907 using a modified Monod equation was regulated by the effects of xylose concentrations and oxygen levels during the fermentation. Xylitol production appeared favorable with maximum yield of 0.43 g/g corresponded to k(L)a value of 29.9 h(-1) with low microbial growth. Sensitivity analysis on the obtained model parameters showed that the maximum specific growth rates (mu(max)) and substrate consumption constant (K-S) are the most influential model parameters for xylitol production.
In the present work, for the first time, a new carboxylate-functionalized walnut shell (CFWS) was prepared via esterification of walnut shell (WS) with isopropylidene malonate. The characterization of the CFWS by different techniques approved that carboxylic groups were introduced onto the surface of WS. The performance of the modified adsorbent was studied for the removal of Pb2+ ions from aqueous solutions in a batch adsorption system. The analysis data showed that the Langmuir isotherm could satisfactorily explain the equilibrium data, and the maximum adsorption capacity for Pb2+ ions was found to be 192.3 mg g(-1) at 0.8 g L-1 of the adsorbent, pH 5.5, and a temprature of 298 K. Two models, namely artificial neural network (ANN) and multiple linear regression (MLR), were used to construct an empirical model for prediction of the removal percentage of Pb2+ ions under different experimental conditions. These models were validated using a test set of 20 data. A comparison between the developed models shows that the ANN model is able to predict the removal percentage of Pb2+ ions more accurately. Consequently, the ANN model could be applied for the design of an automated wastewater remediation plan. Also it has to be noted that the used CFWS was recovered using EDTA-2Na, and employed for the removal of Pb2+ ions from aqueous solutions.
The use of polymers as supports for enzyme immobilization is a strategy that enables to remove the enzymes from a chemical reaction and improve their efficiency in catalytic processes. In this work, cellulose triacetate (CTA) was used for physical adsorption of phospholipase Lecitase ultra (LU). CTA is more hydrophobic than cellulose, shows good performance in the lipases immobilization being a good candidate for immobilization of phospholipases. We investigated the immobilization of LU in CTA, the stability of the immobilized enzyme (CTA-LU) and the performance of CTA-LU using soybean oil as a substrate. LU was efficiently immobilized in CTA reaching 97.1\% in 60 min of contact with an enzymatic activity of 975.8 U.g(-1). The CTA-LU system presents good thermal stability, being superior of the free enzyme and increase of the catalytic activity in the whole range of pH values. The difference observed for immobilized enzyme compared to free one occurs because of the interaction between the enzyme and the polymer, which stabilizes the enzyme. The CTA-LU system was used in the transesterification of soybean oil with methanol, with the production of fatty acid methyl esters. The results showed that CTA-LU is a promising system for enzymatic reactions.
With the aim to utilize deoiled rice bran, an agro-industrial waste, as a feedstock for the co-production of multiple carbohydrases, a fungal strain was isolated which could utilize DORB to co-produce a consortium of cellulases, hemicellulases, pectinase and amylases and was named as Aspergillus niger P-19 after molecular identification. Further, optimization for the co-production of all the enzymes was carried out by one factor at a time approach. Time profile studies of the production of enzymes revealed that 5th day of incubation was best suited for the extraction of enzymes. An initial solid to moisture ratio of 1:1.5 and an inoculum size of 5 x 10(7) spores gds(-1) were found to be optimum for maximum productivities. Enzyme yields were significantly improved with the exogenous supplementation of carbon source, nitrogen source, surfactants and lignocellulosic inducers. This is the first report of its kind where DORB has been utilized for the co-production and co-optimization of eight different enzymes which can have a potential application in biofuel industry as the enzyme preparation could effectively hydrolyze steam pre-treated DORB releasing a total reducing sugars of 356.17 +/- 9.58 mg gds(-1).
Foams are a type of material of great importance, having an extensive range of applications due to a combination of several characteristics, such as ultra-low density, tunable porous architecture, and outstanding mechanical properties. The production of polymer foams worldwide is dominated by those based on synthetic polymers, which might be biodegradable or non-biodegradable. The latter is a great environmental concern and has become a major waste management problem. Foams derived from renewable resources have aroused the interest of researchers, solid foams made from plant polymers in particular. This review focuses on the development of plant polymer-based solid foams and their applications in the food industry over the last fifteen years, highlighting the relationship between their material and structural properties. The applications of these foams fall mainly into two categories: edible foams and packaging materials. Most plant polymers utilized for edible applications are protein-based, while starch and cellulose are commonly used to produce food packaging materials because of their ready availability and low cost. However, plant polymer-based solid foams exhibit some drawbacks related to their high water absorbency and poor mechanical properties. Most research has concentrated on improving these two physical properties, though few studies give a solid understanding and comprehension of the micro- to macrostructural modifications that would allow for the proper handling and design of foaming processes. There are, therefore, several challenges to be faced, the control of solid foam structural properties being the main one.
Lignocellulosic energy crops are promising feedstocks for producing renewable fuels, such as methane, that can replace diminishing fossil fuels. However, there is a major handicap in using lignocellulosic sources to produce biofuels, which is their low biodegradability. In this study, the application and the optimization of a lignocellulose pretreatment process, named alkaline hydrogen peroxide, was investigated for the enhancement of methane production from the energy crop switchgrass. Four independent process variables, solid content (3-7\%), reaction temperature (50-100 degrees C), H2O2 concentration (1-3\%), and reaction time (6-24 h), and three response variables, soluble reducing sugar, soluble chemical oxygen demand, and biochemical methane potential were used in process optimization and modeling. The optimization was performed by two different approaches as maximum methane production and cost minimization. The optimum conditions for the highest methane production were found as 6.65 wt\% solid content, 50.6 degrees C reaction temperature, 2.94 wt\% H2O2 concentration, and 16.05 h reaction time. The conditions providing the lowest cost were 6.43 wt\% solid content, 50 degrees C reaction temperature, 1.83 wt\% H2O2 concentration, and 6.78 h reaction time. For maximum methane production and cost minimization, specific methane yields of 338.52 mL CH4/g VS and 291.34 mL CH4/g VS were predicted with 62.4 \% and 39.8 \% enhancements compared to untreated switchgrass, respectively. Finally, it was found that the predicted methane production for the maximum methane production represents 77 \% of the theoretical methane yield and 82.22 \% energy recovery.
Switchgrass (Panicum virgatum, L., Poaceae) with the advantages of high cellulose yield, and high growth even under low input and poor soil quality, has been identified as a promising candidate for production of low-cost biofuels, papermaking, and nanocellulose. In this study, 12 chemical pretreatments on a laboratory scale were compared for different utilization purposes of switchgrass. It was found that the pretreated switchgrass with sodium hydroxide showed considerable potential for providing mixed sugars for fermentation with 11.10\% of residual lignin, 53.85\% of residual cellulose, and 22.06\% of residual hemicellulose. The pretreatment with 2.00\% (v/v) nitric acid was the best method to remove 78.37\% of hemicellulose and 39.82\% of lignin under a low temperature (125 degrees C, 30 min), which can be used in the production of nanocellulose. Besides, a completely randomized design analysis of switchgrass pretreatments provided the alternative ethanol organosolv delignification of switchgrass for the papermaking industry with a high residual cellulose of 58.56\%. Finally, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR) were carried out to confirm the changes in functional groups, crystallinity, and thermal behavior of the three materials, respectively, from the optimal pretreatments.
In this study, the co-fermentability of four different pretreated corn cob streams at different mixing ratios was assessed. The four streams, denoted DP, DS, HP, and HS, were: two dilute acid pretreatment comprising one purge and one squeeze and two high pressure autohydrolysis comprising one purge and one squeeze. The ``Purge{''
The synthesis of biodiesel from renewable resources has immense potential as a sustainable and cost-ffective energy alternative. In this work, a reusable SO3H functionalized heterogeneous catalyst that has a total acid density of 2.06 mmol/ g was prepared from walnut (Juglans regia) shell powder by low-temperature hydrothermal carbonization (WNS-SO3H). Walnut shell (WNS) contains more lignin (50.3\%), which shows great resistance toward moisture. The prepared catalyst was employed for the effective conversion of oleic acid to methyl oleate by a microwave-assisted esterification reaction. The EDS analysis revealed the significant presence of sulfur (4.76 wt\%), oxygen (51.24 wt\%), and carbon (44 wt\%) content. The results of the XPS analysis confirm the bonding of C-S, C-C, C=C, C-O, and C=O. Meanwhile, the presence of SO3H (the responsible factor for the esterification of oleic acid) was confirmed by FTIR analysis. Under the optimized conditions (9 wt\% catalyst loading, 1:16 oleic acid to methanol molar ratio, 60 min reaction time, and 85 degrees C temperature), the conversion of oleic acid to biodiesel was found to be 99.01 +/- 0.3\%. The obtained methyl oleate was characterized by employing C-13 and H-1 nuclear magnetic spectroscopy. The conversion yield and chemical composition of methyl oleate were confirmed by gas chromatography analysis. In conclusion, it can be a sustainable catalyst because the catalyst preparation controls the agro-waste, a great conversion is achieved due to the high lignin content, and the catalyst was reusable for five effective reaction cycles.
The growing interest in the development of biodegradable polymers as a substitute for non-biodegradable ones has led researchers to look for alternatives for the development of sustainable materials. In this sense, the lignin - widely produced by biorefineries and paper industries - has been shown to be relevant, playing an important role during the preparation of polymers and composites by ring-opening polymerization (ROP). This is partly due to lignin's aliphatic and phenolic reactive hydroxyls that can be used as initiator of cyclic ester monomers, combined with its antioxidant and anti-UV properties, as well as biodegradability. Understanding the role of lignin during the preparation of such environmentally friendly materials can overcome the bottleneck that still remains in this approach. In this review, we address a critical review on the polymer grafting onto reactive hydroxyls from lignin surface by ROP, and the use of such grafted lignin with biodegradable polymer composites. Moreover, we offer a deeper understanding of the role of different types of lignin during such process. We also presented why the surface modification of lignin, as well as the ratio between monomer and initiator have a huge impact on the mechanical, thermal, antioxidant and UV absorbance properties of prepared materials. Applications mainly in biomedical fields were highlighted, but packaging and coatings applications were also covered.
Background and Objective: Nowadays, production of ethanol involves many kinds of plant based materials, from conventionally used starchy materials such as rye, wheat, corn and barley to lignocellulose materials serving in second-generation bioethanol production. While raw materials containing simple sugars do not require such complex mashing processes, starchy and lignocellulose materials need significant processing. This review provides an in-depth description of the structures of starchy raw materials commonly used in production of first-generation ethanol. Furthermore, the review describes the structure of lignocellulose biomasses used for second-generation bioethanol production. Results and Conclusion: Methods commonly used in distilleries to release starch from plant raw materials belong to pressure-thermal pretreatments known as steaming or pressureless liberation of starch methods. Literature shows that amylolysis is strongly determined by the morphology of starch granules. The larger the specific surface area of granules, the greater their susceptibility to amylolysis. The key stage in preparation of starch raw materials for fermentation is starch hydrolysis, which consists of two steps of liquefaction and saccharification. Several species of bacteria (e.g. Bacillus licheniformis) and fungi (e.g. Aspergillus niger) are available that are capable of producing enzymes necessary for starch hydrolysis. Enzymes needed for starch hydrolysis are divided into 1) liquefying enzymes such as alpha-amylase produced by Aspergillus niger and Bacillus licheniformis or can be found in malt and 2) saccharifying enzymes such as glucoamylase, beta-amylase and maltogenic alpha-amylase of fungal, bacterial and malt origins. Proteases and phytases are used to support mashing process hydrolases of non-starch polysaccharides (xylanase and pullulanase).
This work aims to evaluate from an energy and economic perspective the production of essential oil, pectin, and biogas as alternatives to valorize orange peel waste. For this, the chemical characterization, extraction of essential oil, and pectin of industrial of this residue samples were done. Moreover, the remaining solid was used to produce biogas. The experimental results were used as input data to simulate the biorefinery. The mass and energy balances from the simulation were used to perform energy and economic analysis of the biorefinery system analyzing the net present value and processing scale as determining factors. Also, mass and energy efficiency indicators were applied to evaluate the performance of the biorefinery. The experimental essential oil, pectin extraction, and biogas yields 0.61\% w/w (wet basis), 10.35\% w/w (wet basis), and 89.39 Nm(3)/ton OPW mL biogas/g VS with a CH4 content of 66.73\% (59.6 Nm(3)/ton OPW), respectively. The mass and energy indicators show a good performance of the process in terms of mass and energy efficiency indicators. Moreover, the economic analysis leads to observe that the proposed biorefinery is only feasible at low processing scales. In a conclusion, orange peel waste is a potential feedstock to obtain value-added products such as essential oil and pectin and energy vectors such as biogas in an energy and economic feasible way at low scales allowing the implementation of small-scale integrated biorefinery systems.
This work deals with the production of ethanol from phosphoric acid-impregnated, steam-exploded Eucalyptus benthamii. The whole conversion process, addressing pretreatment, enzymatic hydrolysis of the whole slurry, and fermentation of both C5 and C6-sugars including a presaccharification step, is covered in this study. Two separate models were developed to maximize sugar content and minimize inhibitor concentrations, resulting in xylose yields of 50\% and 60\% after pretreatment. In addition, a Liquefaction plus Simultaneous Saccharification and co-Fermentation (L+SScF) was performed to compare the fermentability of the resulting pretreated biomass. After the 6-h liquefaction step using the Celtic CTec2 enzyme from Novozyme and 10\% DW pretreated biomass, the total sugar concentration in the slurry was 47 g/L and 51 g/L for the two conditions respectively. Enzymatic hydrolysis continued during fermentation using an ethanologenic derivative of Escherichia coli K011. The sugars were completely consumed in 96 h with product yields of 0.217 and 0.243 g ethanol/g DW biomass for each condition, respectively. These yields are equivalent to 275 and 304 L/tonne DW, confirming the effectiveness of the L+SScF process using phosphoric-acid-pretreated Eucalyptus. (C) 2014 Elsevier Ltd. All rights reserved.
Recent analyses of cell wall components of various grass mutant and transgenic lines have provided information on characteristic transcriptional regulation of cell wall formation in grasses, although its knowledge yet remains limited compared with that for eudicot cell wall formation. MYB transcription factors, which are regarded as downstream regulators operating under NAM, ATAF1/2, and CUC2 (NAC) domain transcription factors, have been suggested to be involved in direct regulation of cell wall biosynthesis. In this review, we discuss MYB-mediated transcriptional regulation of the biosynthesis of grass lignins, including grass-specific lignin components such as gamma-acyl groups and flavone tricin units. Grass mutant and transgenic lines harboring modified cell-wall-associated MYB genes display altered composition of the gamma-acylated and tricin-incorporated lignin units and/or modified expression of enzyme genes involved in the formation of these grass-specific lignin components along with conserved monolignol biosynthetic genes. These findings implicate important roles for MYB transcription factors in coordinated regulation of grass lignin biosynthesis including gamma-acylated and tricin-incorporated lignin biosynthesis.
This work contrasted gaseous emissions of carbon, sulfur and nitrogen oxides from combustion of several types of biomass including woody, herbaceous and crop-derived wastes, pulverized in the size range of 75-150 mu m. Both raw and torrefied biomass were exposed to high heating rates (10(4)-10(5) K/s) in a laboratory-scale electrically-heated drop-tube furnace, operated at 1400 K. Combustion occurred under fuel-lean conditions. Torrefied biomass has lower volatile matter content, higher fixed carbon content and higher heating value than raw biomass. Results revealed that (a) CO2 emission factors from torrefied biomass were higher than those from raw biomass, reflecting the higher carbon content of the former, however there was no uniform trend in emission factors (kg/GJ); (b) SO2 emission factors of torrefied biomass were lower than those from raw biomass, even if some torrefied biomass types contained higher sulfur mass fractions than their raw biomass precursors. All raw and torrefied biomass, with one exemption, generated lower SO2 emission factors than a typical sub-bituminous coal; (c) torrefied biomass has higher fuel-nitrogen mass fractions than their raw biomass precursors; however, there was no clear trend in NOx emission factors between raw and torrefied biomass, as torrefied herbaceous and woody biomass types generated higher while torrefied crop biomass types generated lower emission factors than their raw biomass precursors. Comparing with the sub-bituminous coal, some raw and torrefied biomass types generated lower and some higher NOx emission factors. Overall, combustion of most types of biomass, either in raw or torrefied state, can result in lower SO2 and NOx emissions factors than those of typical western US sub-bituminous coals while, in principle, generating minimal net emissions of carbon. (C) 2016 Elsevier Ltd. All rights reserved.
A novel strategy for pre-treated biomass detoxification combining emerging green solvents and low environmental impact extraction technologies was evaluated. Steam-exploded biomass was subjected to microwaveassisted or orbital shaking extraction using bio-based or eutectic solvents. The extracted biomass was enzymatically hydrolysed. The potential of this detoxification methodology was studied in terms of phenolic inhibitors extraction and sugar production improvement. The effect of adding a post-extraction water washing step before hydrolysis was also evaluated. Excellent results were achieved when steam-exploded biomass was subjected to the microwave-assisted extraction combined with the washing step. The highest sugar production was achieved when ethyl lactate was used as extraction agent (49.80 \& PLUSMN; 3.10 g total sugar/L) over the control (30.43 \& PLUSMN; 0.34 g total sugar/L). Results suggested that a detoxification step based on green solvents would be a promising option to extract phenolic inhibitors, which can be revalorized as antioxidants, and improve the sugar production from the extracted pre-treated biomass.
The ever-increasing demand for fossil fuels has led to environmental issues and depletion of energy resources, as a consequence, a growing interest in biomass as a promising renewable and sustainable feedstock for biofuels production is developing. In this work, lentil husks (agricultural wastes) and Chlorella vulgaris (microalgae) were selected to investigate their interaction during co-pyrolysis process. Using a response surface methodology (RSM), a series of experiments were designed and carried out in a fixed bed reactor varying the temperature of 400-600 degrees C, heating rate of 5-25 degrees C/min and algae to husk blend ratios of 0, 25, 50, 75, 100 wt\% at constant flow rate of argon carrier gas, 0.4 L min-1. The yield of Bio-oil and biochar as co-pyrolysis products were studied both quantitatively and qualitatively. The results unraveled a significant improvement on bio-oil yield by addition of C. vulgaris to lentil husk. Bio-oil yield increased from 13.8\% to 20.8\% by increasing algae content from 0\% to 100\% (T = 500 degrees C, HR = 15 degrees C min-1). While at T = 600 degrees C, the gas yield increased to 40.15\%. and lower temperature (400 degrees C), favored biochar formation (39.5\%), finally optimization results could lead to bio-oil yield of 18\% (T = 479 degrees C, HR = of 16 degrees C min-1, R = 54\%). The quality of the product at optimized level was featured by a rise in the carbon and a decrease in the oxygen content of bio-oil, and a bio-oil with improved higher heating value was obtained. The results of volatile products analyzed by Gas chromatography-mass spectrometry (GC-MS) showing that, the co-pyrolytic oil was rich in alkanes and aromatics compounds. Synergistical interactions between C. vulgaris and lentil husk, showed that alcohols, ketones and esters went through a remarkable reduction and phenols formation as valuable chemical compounds was improved.
In this research study, the biosorption of Synolon red 3HF and Synolon black HWF-FS dyes onto novel biomasses mustard oil cake and linseed oil cake, respectively, was investigated in the batch mode using different process parameters like pH, particle size, biosorbent dose, initial dye concentration, contact time, and temperature. Maximum biosorption capacity was observed at pH 1 for Synolon red 3HF onto mustard oil cake and pH 2 for Synolon black HWF-FS onto linseed oil cake. The biosorption capacity was efficient at the smallest particle size of biosorbent. The amount of dye sorbed (mg/g) decreased with the decrease in biosorbent dose and increased with increase in initial dye concentration and temperature. The Freundlich isotherm model was best fitted to experimental data. The biosorption followed the pseudo-second-order kinetic model suggesting a chemisorption mechanism. An increase of biosorption capacity with temperature shows an endothermic nature of the process. In this research, the influence of electrolytes, heavy metals, and surfactants on the removal of dyes was also examined.
I have determined whether the presence of an endophytic bacterium alters the chemical properties of inoculated plants and compared decomposition of colonized residues with control residues in soil. Greenhouse-grown corn (Zea mays L.) plants (18 days old) were inoculated with either the endophytic bacteria Clavibacter xyli subsp. cynodontis (MDE1) or a genetically engineered construction of C. xyli subsp. cynodontis which was transformed by inserting a gene encoding for production of a delta-endotoxin from Bacillus thuringiensis subsp. kurstaki (MDR1.3). Leaves and stalks were harvested at maturity and various chemical and physical properties analyzed. In addition, leaf and stalk residues were incorporated into soil to determine the extent of their decomposition in a 63 day laboratory incubation study. Leaf residues from plants inoculated with MDR1.3 retained significantly more water than did those inoculated with buffer or MDE1. Leaves of inoculated plants contained significantly more C than did stalks of inoculated plants. Soluble proteins were the major contributors to the C content of leaves, whereas, soluble carbohydrates were predominant in the stalks. Inoculation with either MDR1.3 or MDE1 appeared to increase the quantity of N present in all plant parts. During early stages, leaf residues contained more readily decomposable substrates than did stalk residues. Leaves from plants inoculated with buffer decomposed significantly more after 63 days than those from plants inoculated with MDE1 or MDR1.3. In contrast, corn stalks inoculated with MDR1.3 decomposed significantly more than those inoculated with buffer or MDE1. Over the 63 day incubation ca 33\% of the corn residues were decomposed. Although the presence of the endophytes, MDE1 and MDR1.3, during plant growth had some influence on chemical and physical properties of the residues, the extent of residue decomposition in soil (CO2 evolved in 63 days) was not substantially different.
A novel granular adsorbent material containing zero-valent iron (ZVI-GAM) was prepared with fly ash as skeletal material, bentonite as binder and Enteromorpha prolifera as pore former. ZVI was synthesized by direct reduction of iron ore tailings powder with the coke as reductant in high temperature reducing atmosphere and embedded in the fly ash-based porous adsorbent, which could reduce the agglomeration and oxidation of ZVI. The structure of ZVI-GAM was characterized by SEM, EDX, XRD, FT1R and BET. The removal amount of crystal violet (CV) and methylene blue (MB) was evaluated at different contact time, initial dye concentration, pH values and temperature. The adsorption isotherms of CV and MB fitted well to the Langmuir model. The maximum removal capacity of ZVI-GAM for CV and MB was found to be 172.41 mg/g and 151.52 mg/g, respectively. The adsorption processes of CV and MB could be described by a pseudo-second-order kinetic model. The reduction kinetics of CV by ZVI-GAM fitted to pseudo-first-order kinetics model. The results indicated that chemisorption and reduction controlled the removal process of CV while chemisorption only controlled the removal process of MB. The thermodynamic study indicated that the adsorption processes of CV and MB were found to be endothermic and spontaneous. Therefore, ZVI-GAM was an effective, low-cost and recyclable material for dye removal. (C) 2017 Elsevier B.V. All rights reserved.
Efficient, low-cost enzymatic hydrolysis of lignocellulosic biomass is essential for cost-effective production of bioethanol. The aim of this study was to establish a fungal fermentation-based strategy for the economic enzymatic conversion of pineapple peel into fermentable sugars. Trichoderma viride was grown on passion fruit peel in order to improve its beta-glucosidase production, and a crude extract was then used to hydrolyze pineapple peel. The effects of medium pH, cultivation time, and passion fruit peel concentration on beta-glucosidase production were evaluated using a central composite rotational design (CCRD) combined with response surface methodology (RSM). Optimal beta-glucosidase activity of 2.40 U mL(-1) was found after 6.5 days of cultivation in medium at pH 6.0, containing 2.0 \% passion fruit peel. Saccharification of pineapple peel was also optimized by RSM and CCRD with respect to pH, temperature, beta-glucosidase concentration, and reaction time and proceeded optimally at pH 4.0, 55 A degrees C, with a beta-glucosidase loading of 31.25 U g(-1) dry feedstock and 75 h of reaction. Under these conditions, T. viride crude extract hydrolyzed pineapple peel with a glucose yield of 65.3 \%. This study therefore presents passion fruit peel as an attractive raw material for the production of beta-glucosidases. In addition, it describes an improved, effective, and low-cost enzymatic method for the production of fermentable sugars from pineapple peel, an abundant and inexpensive agro-industrial waste.
Xyloglucan-specific endo-beta-1,4-glucanases (Xegs, EC 3.2.1.151) exhibit high catalytic specificity for beta-1,4 linkages of xyloglucan, a branched hemicellulosic polysaccharide abundant in dicot primary cell walls and present in many monocot species. In nature, GH12 Xegs are not associated with carbohydrate-binding modules (CBMs), and here, we have investigated the effect of the fusion of the xyloglucan-specific CBM44 on the structure and function of a GH12 Xeg from Aspergillus niveus (XegA). This fusion presented enhanced catalytic properties and conferred superior thermal stability on the XegA. An increased k (cat) (chimera, 177.03 s(-1); XegA, 144.31 s(-1)) and reduced K-M (chimera, 1.30 mg mL(-1); XegA, 1.50 mg mL(-1)) resulted in a 1.3-fold increase in catalytic efficiency of the chimera over the parental XegA. Although both parental and chimeric enzymes presented catalytic optima at pH 5.5 and 60 A degrees C, the thermostabilitiy of the chimera at 60 A degrees C was greater than the parental XegA. Moreover, the crystallographic structure of XegA together with small-angle X-ray scattering (SAXS) and molecular dynamics simulations revealed that the spatial arrangement of the domains in the chimeric enzyme resulted in the formation of an extended binding cleft that may explain the improved kinetic properties of the CBM44-XegA chimera.
Quorum-sensing (QS) systems exist universally in bacteria to regulate multiple biological functions. Klebsiella pneumoniae, an industrially important bacterium that produces bio-based chemicals such as 2,3-butanediol and acetoin, can secrete a furanosyl borate diester (AI-2) as the signalling molecule mediating a QS system, which plays a key regulatory role in the biosynthesis of secondary metabolites. In this study, the molecular regulation and metabolic functions of a QS system in K. pneumoniae were investigated. The results showed that after the disruption of AI-2-mediated QS by the knockout of luxS, the production of acetoin, ethanol and acetic acid were relatively lower in the K. pneumoniae mutant than in the wild type bacteria. However, 2,3-butanediol production was increased by 23.8\% and reached 54.93 g/L. The observed enhancement may be attributed to the improvement of the catalytic activity of 2,3-butanediol dehydrogenase (BDH) in transforming acetoin to 2,3-butanediol. This possibility is consistent with the RT-PCR-verified increase in the transcriptional level of budC, which encodes BDH. These results also demonstrated that the physiological metabolism of K. pneumoniae was adversely affected by a QS system. This effect was reversed through the addition of synthetic AI-2. This study provides the basis for a QS-modulated metabolic engineering study of K. pneumoniae.
This work investigated the effect of ethylenediamine pretreatment on reducing enzyme loading in high gravity fermentation. At optimal conditions of ethylenediamine pretreatment, 85.5\% lignin was removed. Enzyme adsorption analysis using a fluorescent cellulose-binding protein showed 35.2\% increase of productive adsorption of enzymes to ethylenediamine pretreated biomass, which was caused by high delignification and dramatically increased surface roughness and porosity. In SScF at 15\% glucan loading, up to 82.2 g/L ethanol was achieved with a relatively low enzyme loading of 3.6 FPU/g dry matter. It suggested that the remarkably high digestibility of EDA pretreated corn stover could effectively reduce the enzyme loading in the high gravity fermentation of cellulosic ethanol.
With the increasing consumption of fossil fuels and the growing concerns about climate change, biomass is drawing increasing attention as a renewable energy source due to its advantages of renewal and abundance. Biomass can be converted into energy using bio-chemical and thermo-chemical processes, but the thermo-chemical conversion technology finds its dominance because of high efficient conversion to gas, liquid and solid products under thermal conditions. Biomass pretreatment can alter the physical features and chemical composition/structure of lignocellulosic materials. The pretreatment step has a significant influence on the quality and yield of products obtained from thermo-chemical conversion biomass. In this review, we discuss the applications of various pretreatment methods in the biomass thermo-chemical conversion, including torrefaction and gasification, pretreatment and biomass pyrolysis, pretreatment and biomass liquefaction. Torrefaction improves the hydrophobicity and grindability characteristics of biomass materials. Water or acid washing pretreatment can remove metal ions from biomass and the change in products distribution during the biomass pyrolysis is more obvious. Biomass pretreatment and liquefaction can increase the bio-oil yield and decrease the optimum reaction temperature compared to the untreated biomass liquefaction experiments.
Research on chemical modification of pineapple peel fibre with succinic anhydride was carried out to create a novel adsorbent for Cu2+, Cd2+ and Pb2+ removal from aqueous solution. After pretreatment with iso-propyl alcohol and NaOH, pineapple peel fibre was modified via reaction with succinic anhydride for introduction of carboxylic functional groups. The modified pineapple peel fibre was characterized with Fourier transform infrared (FTIR) spectroscopy and evaluated for its adsorptive ability for Cu2+, Cd2+ and Pb2+ from synthetic metal solutions. The FTIR analysis proved the introduction of carboxylic functional groups in the backbone of the modified pineapple peel fibre. The modified pineapple peel fibre showed higher adsorptive capacity for Cu2+, Cd2+ and Pb2+ compared with raw pineapple peel and pineapple peel fibre pretreated with iso-propyl alcohol. The adsorption of Cu2+, Cd2+ and Pb2+ on the modified pineapple peel fibre depended on solution pH value, adsorption time and initial metal concentration. The maximum adsorption capacities of the modified fibre were observed at pH 5.4 for Cu2+ (27.68 +/- 0.83 mg g-1 or 0.44 mmol g-1), at pH 7.5 for Cd2+ (34.18 +/- 1.02 mg g-1 or 0.30 mmol g-1) and at pH 5.6 for Pb2+ (70.29 +/- 2.11 mg g-1 or 0.34 mmol g-1) respectively. The adsorption followed the pseudo-second-order kinetics model and the experimental data coincided well with the Langmuir model.
Herein, walnut shell (WS) was utilized as the raw material for the production of purified cellulose. The production technique involves multiple treatments, including alkaline treatment and bleaching. Furthermore, two nanocellulose materials were derived from WS by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation and sulfuric acid hydrolysis, demonstrating the broad applicability and value of walnuts. The micromorphologies, crystalline structures, chemical functional groups, and thermal stabilities of the nanocellulose obtained via TEMPO oxidation and sulfuric acid hydrolysis (TNC and SNC, respectively) were comprehensively characterized. The TNC exhibited an irregular block structure, whereas the SNC was rectangular in shape, with a length of 55-82 nm and a width of 49-81 nm. These observations are expected to provide insight into the potential of utilizing WSs as the raw material for preparing nanocellulose, which could address the problems of the low-valued utilization of walnuts and pollution because of unused WSs.
The anatomical characteristics, chemical composition, enzymatic hydrolysis efficiency and lignin characteristics of four energy crops (switchgrass, Miscanthus x giganteus, Hybrid Pennisetum, and Triarrhena lutarioriparia) before and after hydrothermal treatment (180 degrees C, 1 h) were investigated comprehensively to evaluate their potential for the bioenergy production. The hydrothermal treatment resulted in the deconstruction of the biomass cell walls and redistribution of the main components, accompanying with the removal of most hemicelluloses and partial lignin as well as favorable exposure of cellulose. These alterations significantly increased the efficiency of enzymatic hydrolysis, and the different recalcitrance of the four feedstocks was evenly erased by hydrothermal treatment. Among the four crops, Hybrid Pennisetum. with high cellulose and low lignin contents had a better performance in the enzymatic hydrolysis process both before and after treatment. Meanwhile, the maximum concentration of low degree of polymerization xylo-oligosaccharides (2-6) and the lowest amount of degraded products were obtained from Hybrid Pennisetum during the treatment process. Moreover, the structural features of the residual lignin in the treated substrates were elaborately analyzed for deeply understanding the fundamental chemistry of lignin during the treatment. The present study is beneficial to the fully effective utilization of biomass components and extension of the energy sources.
The aim of this study was to evaluate the influence of recycling the liquid fraction of pretreatment with alkaline hydrogen peroxide (AHP) on the hydrolysis of corn stover. Corn stover was pretreated in the traditional condition with 7.5\% v/v H2O2. After pretreatment, the solids were separated from the liquid fraction and five successive reuse cycles of the liquid fraction were tested. The solid fraction from pretreatment in each recycle was submitted to enzymatic hydrolysis. The number of recycles had a linear negative effect (R-2 = 0.98) on biomass delignification efficiency and also affected negatively the enzymatic conversion efficiency. Despite the decrease in efficiency after each recycling step, reuse of the liquid fraction leads to reduction in water, H2O2 and NaOH consumption of up to 57.6\%, 59.6\% and 57.6\%, respectively. These findings point to an efficient recycling technology, which may reduce costs and save water. (C) 2017 Elsevier Ltd. All rights reserved.
A fungus capable of producing ethanol from various carbon substrates was screened for direct ethanol production from lignocellulose. Fusarium moniliforme BIOTECH 3170 produced ethanol from glucose, xylose, and cellobiose after three days with theoretical yields of 86.4\%, 68.6\%, and 45.4\%, respectively. The coculture of glucose and xylose progressed sequentially at 79.2\% of the theoretical yield, with both sugars completely consumed in five days. The solid-state consolidated bioprocessing of cellulose produced 25.2 g/L of ethanol after 20 days. After 28 days of the integrated biodelignification and consolidated bioprocessing of Napier grass at solid-state conditions, up to 10.5 g/L of ethanol was produced, corresponding to an ethanol yield of 0.032 g/g biomass. Given a sufficient carbon source, the screened fungus could produce up to 42.06 g/L ethanol. F. moniliforme BIOTECH 3170 demonstrated the characteristics of a fungus for potential ethanol production from cellulose, mixed sugars, and lignocellulosic materials.
The natural resistance to enzymatic deconstruction exhibited by lignocellulosic materials has designated pretreatment as a key step in the biological conversion of biomass to ethanol. Hydrothermal pretreatment in pure water represents a challenging approach because it is a method with low operational costs and does not involve the use of organic solvents, difficult to handle chemicals, and external liquid or solid catalysts. In the present work, a systematic study has been performed to optimize the hydrothermal treatment of lignocellulosic biomass (beech wood) with the aim of maximizing the enzymatic digestibility of cellulose in the treated solids and obtaining a liquid side product that could also be utilized for the production of ethanol or valuable chemicals. Hydrothermal treatment experiments were conducted in a batch-mode, high-pressure reactor under autogeneous pressure at varying temperature (130220?degrees C) and time (15180 min) regimes, and at a liquid-to-solid ratio (LSR) of 15. The intensification of the process was expressed by the severity factor, log?Ro. The major changes induced in the solid biomass were the dissolution/removal of hemicellulose to the process liquid and the partial removal and relocation of lignin on the external surface of biomass particles in the form of recondensed droplets. The above structural changes led to a 2.5-fold increase in surface area and total pore volume of the pretreated biomass solids. The enzymatic hydrolysis of cellulose to glucose increased from less than 7 wt?\% for the parent biomass to as high as 70 wt?\% for the treated solids. Maximum xylan recovery (60 wt?\%) in the hydrothermal process liquid was observed at about 80 wt?\% hemicellulose removal; this was accomplished by moderate treatment severities (log?Ro=3.84.1). At higher severities (log?Ro=4.7), xylose degradation products, mainly furfural and formic acid, were the predominant chemicals formed.
Hollow glass microspheres (HGM), as a promising hollow spherical ultra-light material, have the advantages of uniform particle size, regular shape, high mechanical strength and stable physical and chemical properties. It has been widely utilized in many fields but its application in water treatment is yet to be developed. Herein, a novel self-floating composite adsorbent was obtained by forming a poly(dopamine) (PDA) biomass coating on the surface of HGM and introducing sulfonic acid groups. The hollow composite material (HGM@PDA-SO3H) was utilized in the adsorptive elimination of tetracycline (TC) from aqueous solutions. In addition to great adsorption performance, HGM@PDA-SO3H also exhibited satisfactory self-floating solid-liquid separation capability. Langmuir, pseudo second-order and Elovich models correlate isotherms and kinetic data relatively well, respectively. The theoretical saturated TC adsorption amount of HGM@PDA-SO3H evaluated by Langmuir model reached 333.70 mg g(-1). Thermodynamic analysis confirmed the spontaneous exothermic property of the adsorption process. There was no serious decline in the adsorption of TC by the material after 5 adsorption cycles, and the adsorbent saturated with contaminants could be easily regenerated via solution desorption, reflecting its satisfactory renewability and stability. Based on the results of batch experiments and character-ization analysis, it could be concluded that the corresponding adsorption mechanisms mainly involve electro-static attraction, hydrogen bonding and pi-pi stacking interactions. This research aimed to decorate HGM with biomaterials and apply it in the adsorptive purification of TC-contaminated water, which brought some insights and inspiration for the environmental application of HGM, and proved its potential applicability.
Response surface methodology (RSM) and artificial neural network (ANN) were used to generate a model for the optimization of fluoride removal using chemically activated Dalbergia sissoo sawdust (CADS). The single and collective effects of process parameters, i.e., solution pH, CADS dose, initial fluoride concentration, and contact time, were studied. The point of zero charge was found to be 4.2 with zeta potential analysis. In the first phase, a single-parameter study was performed to reveal dependency of fluoride removal on a particular process parameter. Positive effects of increment in CADS dose and contact time and negative effects of solution pH and initial fluoride concentration were observed. The second phase included RSM in which analysis of variance (ANOVA) was applied to test the feasibility of the mathematical model. The F value 1.91, R-2 value 0.87, and P value 0.11 show significance of the proposed model. Results obtained from the experiment set for central composite design (CCD) were used to predict the ANN response. Reasonable acceptable values of regression for training, test, and validation (0.76, 0.93, and 0.37) represent the suitability of the model. The ANN predicted 22.1\% fluoride removal, which was close to the actual value (20.1\%) and was comparable with CCD prediction (25.0\%). BET surface area of CADS was found to be 76.33 m(2)/g. FTIR was performed to recognize the functional groups available for fluoride binding while SEM and EDX were conducted to ensure the changes in adsorbent surface morphology. Regeneration of CADS was feasible using an alkali medium. This study shows that CADS can be used for fluoride removal from aqueous stream in an efficient way.
The production of fungal biocontrol agents by solid-state fermentation (SSF) processes in inert supports demands deeper studies in SSF-modelling and SSF-optimisation to cope with scale-up issues. Here, we report the systematic application of fractional factorial and central composite designs to optimise the conidia productivity and maximum specific growth rate of the biological control candidate Trichoderma asperellum strain Th204 using two inert supports: polyurethane foam (PUF) and rice husk (RH), in a pilot 16 L fixed bed fermenter. By using response surface methodology, 2D contour graphs and Spearman's correlation coefficients, axial temperature, conidia concentration, bed moisture and pressure drop gradients were modelled. C:N ratio and airflow rate were identified as significant factors. Optimal conditions using PUF a C:N ratio of 18.1 and airflow of 0.8 m(3) h(-1) were found, with the highest productivity of 3.09 x 10(7)conidia g(-1) initial dry matter h(1). Polynomial models and response surfaces found in this study are advantageous to design strategies to scale-up the SSF process in fixed bed fermenters for fungal biological control candidates.
This work aims at developing a continuous intensified green process to extract high-value added molecules from industrial hemp by-products. Hemp hurds and hemp dust were studied as potential sources for the production of two hydroxycinnamic acids (HCA): ferulic (FA) and p-coumaric acids (p-CA). Prior to pilot scale extraction, FA and p-CA analytical contents were evaluated to 0.3 and 3.5 g/kg dry matter (DM) for hemp hurds and 0.1 and 0.8 g/kg DM for hemp dust as potentials of reference. The continuous pilot scale extraction was then carried out using twin-screw extrusion. Mild conditions were developed: 50 degrees C, alkaline aqueous or hydroalcoholic solvent (less than 0.5 M NaOH) and low liquid to solid ratios. The mechanical effect helps the diffusion of the solvent, promotes the hydrolysis of the ester and ether bonds and favors the extraction of HCA in a short time. Yields in p-CA and FA reached 50\% and 33\% of the free and bound contents for hemp hurds. For hemp dust, all of p-CA was extracted whereas 60\% of FA was recovered. The solid residue may be submitted to a second extraction stage with a polar solvent in order to increase HCA recovery. Extraction by extrusion could be seen as an alternative green processing technique as it is responsible for a reduction of extraction time and energy and a decrease in solvent and reagent consumptions.
Hemicellulose, the second, most common polysaccharide in nature constitutes approximately 20-35\% of lignocellulosic biomass. Effective utilization of biomass, hitherto underutilized, is gaining tremendous importance for the production of energy, fuels, and chemicals. Amongst the vast array of chemicals derived from lignocellulosics, furfural is the key chemical that finds wide applications in oil refining, plastics, pharmaceutical and agrochemical industries. There is no synthetic route for the production of furfural. A few conventional technologies currently in practice for its separation and subsequent isolation are appropriately reviewed. Major disadvantages associated with processes currently used for the production of furfural based on acid-catalyzed hydrolysis have been discussed. A need to develop a process which is devoid of all the shortcomings associated with conventional process is emphasized. Several important aspects of chemistry underlying the acid hydrolysis of xylose are discussed. The importance of myriad pre-treatment steps involved to surmount the physical and chemical barriers and to liberate xylose from the confines of acid-resistant layer of lignin has been emphasized. New developments in the production of furfural from cyclodehydration of xylose using solid acid catalysts in the recent past have been reviewed appropriately in present communication. Finally, the production of furfural and furfuryl alcohol, their domestic market and export in China deserve some coverage and therefore have appropriately been discussed as well. (c) 2008 Society of Chemical Industry and John Wiley \& Sons, Ltd
Corn stover was subjected to dilute sulfuric acid pretreatment to assess the impact of pretreatment conditions on lignin extractability, properties, and utility as a phenol replacement in wood phenol-formaldehyde (PF) adhesives. It was identified that both formic acid and NaOH could extract and recover 60-70\% of the lignin remaining after pretreatment and enzymatic hydrolysis under the mildest pretreatment conditions while simultaneously achieving reasonable enzymatic hydrolysis yields (> 60\%). The availability of reaction sites for the incorporation of lignins into the PF polymer matrix (i.e., unsubstituted phenolic hydroxyl groups) was shown to be strongly impacted by the pretreatment time and the recovery. Finally, a lignin-based wood adhesive was formulated by replacing 100\% of the phenol with formic-acid-extracted lignin, which exhibited a dry shear strength exceeding a conventional PF adhesive. These findings suggest that both pretreatment and lignin extraction conditions can be tailored to yield lignins with properties targeted for this co-product application.
This study aimed to evaluate the efficacy of using the byproduct of Moringa oleifera Lam. seeds as an adsorbent for removal of cadmium (Cd) from contaminated water. The material characterization was performed by scanning electron microscopy, infrared spectroscopy, and point of zero charge. The effects of the adsorbent mass, solution pH, contact time, and temperature were evaluated. In the preliminary studies, the mass of adsorbent (200-1200 mg) and pH conditions (5.0, 6.0, and 7.0) were varied. The time studies were performed at 20-180 min and the temperature studies at the range of 25-65 degrees C. The optimal conditions of adsorption obtained were 400 mg of adsorbent mass, 7.0 pH, and 160 min contact time with the adsorbent. The isotherms of adsorption were linearized according to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models. The results showed better fit by the Freundlich and D-R models for Cd adsorption, describing a multilayer adsorption and, according to the value of the sorption energy (E), it has chemical nature. The maximum capacity of adsorption (Q(m)) obtained was 7.864 mg g(-1). For a comparative study, the activated carbon (P. A.) was used applying the same optimal conditions used in the adsorption isotherms and desorption process for the biosorbent, obtaining a Q(m) as 32.884 mg g(-1). The average desorption percentage showed that adsorbents have strong interaction with the metal. Based on these results, it was concluded that the biosorbent was effective in remediation of solutions containing Cd and thus the use of this alternative material is a viable option, since it has low cost and it is a byproduct which has not undergone previous treatment.
As the global demand for plastics continues to grow, plastic waste is accumulating at an alarming rate with negative effects on the natural environment. The industrially compostable biopolymer poly(lactic acid) (PLA) is therefore being adopted for use in many applications, but the degradation of this material is slow under many end-of-life conditions. This Perspective explores the feasibility of accelerating the degradation of PLA through the formation of PLA-plant fiber composites. Topics include: (a) key properties of PLA, plant-based fibers, and biocomposites; (b) mechanisms of both hydrolytic degradation and biodegradation of PLA-fiber composites; (c) end-of-life degradation of PLA and PLA-plant fiber composites in aerobic and anaerobic conditions, relevant to compost, soil and seawater (aerobic), and landfills (anaerobic); and (d) sustainability and environmental impact of PLA and PLA-plant fiber composites, as evaluated using life cycle assessment. Additional degradation modes, including thermal and photodegradation, which are relevant during processing and use, have been omitted for clarity, as have other types of PLA biocomposites. Multiple studies have shown that the addition of some types of plant fibers to PLA (to form PLA biocomposites) accelerates both water transport in the material and hydrolysis, presenting a possible avenue for improving the end-of-life degradation of these materials. To facilitate the continued development of materials with enhanced biodegradability, we identify a need to implement testing protocols that can distinguish between different degradation mechanisms.
Recently, the world is experiencing a shift from petroleum refineries to biorefineries due to fossil fuel depletion and environmental concerns. To achieve sustainable development of biorefineries and other components of the biofuel production process, eco-friendly and cost-effective approaches are necessary. Therefore, lignocellulosic biomass (LCB) must be exploited in biorefineries for the generation of a broad spectrum of products. The complex structure of LCB prevents its direct saccharification by enzymatic means, so pretreatment is necessary. There are several pretreatment technologies for disrupting the lignocellulosic structure, but hydrothermal pretreatment is the leading pretreatment technology for recovering hemicellulose fraction with a low number of inhibitors and an increased amount of cellulose. The severity of hydrothermal pretreatment plays a principal role in affecting cellulose, hemicellulose, and lignin structure. A detailed account of microwave-assisted hydrothermal pre-treatment technologies and the cost-effectiveness, eco-friendliness, and upcoming challenges of this technology for commercialization with the probable solution is presented.
Biochemical conversion of lignocellulosic feedstocks to advanced biofuels and other bio-based commodities typically includes physical diminution, hydrothermal pretreatment, enzymatic saccharification, and valorization of sugars and hydrolysis lignin. This approach is also known as a sugar-platform process. The goal of the pretreatment is to facilitate the ensuing enzymatic saccharification of cellulose, which is otherwise impractical due to the recalcitrance of lignocellulosic feedstocks. This review focuses on hydrothermal pretreatment in comparison to alternative pretreatment methods, biomass properties and recalcitrance, reaction conditions and chemistry of hydrothermal pretreatment, methodology for characterization of pretreatment processes and pretreated materials, and how pretreatment affects subsequent process steps, such as enzymatic saccharification and microbial fermentation. Biochemical conversion based on hydrothermal pretreatment of lignocellulosic feedstocks has emerged as a technology of high industrial relevance and as an area where advances in modern industrial biotechnology become useful for reducing environmental problems and the dependence on fossil resources.
During ethanol production, the ratio of various sources of starch-hydrolyzing enzymes significantly influences hydrolysis efficiency in a very high gravity (VHG) system. In this study, the enzyme matching approach was proposed to optimize liquefaction and saccharification yield of cassava root and cassava starch. For fresh cassava root, the synergistic effect of using Techzyme Q-Add enzyme (93 degrees C pH 5.6) for liquefaction and GC 147 enzyme (61.5 degrees C pH 4.2) for saccharification achieved the highest yield among all enzyme-matching designs. At 25\% solid, highest total reducing sugar (TRS) yields from sequential liquefaction and saccharification of cassava starch, fresh cassava, and dry cassava were 87.9\%, 85.1\%, and 70.0\% corresponding to 286.8, 249.4, and 241.1 g/L, respectively. For VHG ethanol fermentation by Saccharomyces cerevisiae TISTR 5606, separate liquefaction and simultaneous saccharification and fermentation (SLSSF) gave a significantly higher ethanol concentration compared with separate liquefaction and saccharification and fermentation (SLSF). From a 35\% solid SLSSF system, the highest ethanol produced at 30 degrees C was 27.3 g/L from 72 h, respectively. The results suggested that SLSSF could effectively shorten the time course of the whole process for liquefaction, saccharification, and fermentation from 74 h to only 26 h for similar ethanol production yields.
The macadamia productive process generates a large amount of waste, such as walnut carpel, that is improperly disposed of in most instances. This residue is a promising feedstock for biofuel production and it can be converted through thermochemical routes. Liquid pyrolysis products obtained contain a bio-oil with great potential for the production of fuels and fine chemicals. The goal of this study was to characterize the macadamia carpel for the first time by ultimate, proximate, FTIR, and TG analysis, as well as HHV determination, which showed this is a potential candidate for thermochemical conversion processes. Thermodynamic and kinetic pyrolysis behaviours were evaluated using Ozawa, Kissinger, Starink, and KAS isoconversional models (140.12, 137.69, 137.41, and 146.63 kJ mol(-1), respectively), which attested to the product favourability and the operational viability. Additionally, the master plot method was applied to complete the kinetic description, which identified diffusion and nucleation mechanisms during the carpel degradation. After 50\% conversion, the third-order reaction mechanism occurred due to a predominant lignin decomposition. The results showed that the macadamia carpel properties are similar to traditional feedstock, that it may be decomposed into bio-oil, and that it can be used as an alternative energy source or bio-chemicals precursor.
The threat of oil pollution increases with the expansion of oil exploration and production activities, as well as the industrial growth around the world. The study on the treatment of oily wastewater is a critical issue to the environmental protection as oil caused problems to the wastewater treatment facilities. Although oil particles can efficiently be removed by advanced technologies, the treatments are usually expensive and difficult to maintain. Adsorption and coalescence filtration are promising choice of treatment for its simplicity, effectiveness, and feasibility when appropriate sorbent is used. This review discusses the recent papers on the use of natural fibrous sorbent for removal of oil from wastewater, and its current development. With their excellent oil removal properties, environmental friendliness, easy availability, and feasibility, natural fibrous sorbents are an attractive alternative for oily wastewater treatment. (C) 2013 Elsevier B.V. All rights reserved.
Costs and conversion efficiency associated with cellulase preparations have been identified as factors impeding the development of cellulose hydrolysis-based technologies. Supplementing enzymes to fungal cocktails has been practiced; however, the costs associated offset the benefits of an increase in hydrolysis. This work explores the benefits of using maize bran as a substrate in a sequential fermentation mode to produce beta-glucosidase (BGL), intended for augmenting commercial fungal cellulases. Aspergillus tubingensis was grown for BGL production on maize bran in sequential solid-state and submerged fermentation (SsF-SmF). In these experiments, a solid substrate was soaked with a nutrient medium and later with media containing 1\% solid substrate. The sequential process was observed to yield a two-fold improvement in BGL production in comparison to traditional methods. The predominance of dispersed mycelia in the sequential process was noted and concluded to be the influencer for improved enzyme secretion. Different substrates were evaluated among which delignified maize bran was found to be the most suitable. The batch fermentation yielded BGL productivity of 400 +/- 8.64 CBU/l/day, while the repeated fed-batch mode improved the BGL productivity to 647 +/- 13.33 CBU/l/day and 987 +/- 12.5 CBU/l/day for 50 and 25\% medium replacement, respectively. Supplementing commercial cellulases with the produced BGL was observed to increase cellulose hydrolysis by 20\%. This work, therefore, helps explore the potential of maize bran as a substrate for sequential SsF-SmF for BGL production in a cost-effective manner.
Brewery spent grain (BSG) is an industrial waste stream with large potential for biorefining purposes. This work evaluated the production of volatile fatty acids (VFAs) by a two-step process using BSG as renewable feedstock by combining a single direct hydrolysis step (without removing the acid or potential inhibiting compounds) with an acidogenic fermentation step of the carbohydrate rich leachate. For the first step, a thermal diluted acid hydrolysis was carried (20 min at 121 degrees C), using eighteen different combinations in terms of total solid (TS) of BSG (4, 7 and 10 \% w/w) and H2SO4 (0.0, 0.5, 1.0, 1.5, 2.0 and 3.0 \% v/v). The 7.0 \% TS of BSG and 1.5 \% of H2SO4 combination was the most efficient in terms of total carbohydrate recovery (0.44 g of total carbohydrates per gram of TS). For the second step, an acidogenic batch fermentation of the hydrolysate was performed using anaerobic granular sludge at five different pH conditions (uncontrolled pH from an initial pH 7.0, and constant pH controlled at 4.5, 5.0, 6.0 and 8.0). The highest VFAs concentration was obtained at pH 6.0 and reached 16.89 (+/- 1.33) g COD/L, composed of mainly (99.5-99.8 \%) acetate and butyrate.
The walnut shell, as local agriculture biomass of Yasouj city (Iran), was used as raw material to synthesize activated carbon. The optimum condition of the synthesis process was determined using Taguchi experimental design and the adsorption abilities of the produced activated carbon toward Zn (II) was used as response. The analysis of data showed that the impregnation ratio and activation time are more effective parameters. The activated carbon synthesized at optimum condition was a mesopore material with the specific surface area of 1388 m(2)g(-1). The optimum activated carbon was applied as the adsorbent for Zn (II) removal from aqueous solution under the different operating condition including initial pH, contact time and initial concentration. The kinetics analysis of data indicates the chemical nature of Zn ions adsorption. The produced carbon was able to adsorb 89 mg Zn (II) per each gram. The adsorption ability of produced carbon was evaluated in three adsorption/desorption cycles in a continuous adsorption system.
Bacterial species can adapt to significant changes in their environment by mutation followed by selection, a phenomenon known as ``adaptive evolution.{''
Agar substrates for in vitro culture are well adapted to plant micropropagation, but not to plant rooting and acclimatization. Conversely, paper-pulp-based substrates appear as potentially well adapted for in vitro culture and functional root production. To reinforce this hypothesis, this study compares in vitro development of nemesia on several substrates. Strong differences between nemesia roots growing in agar or in paper-pulp substrates were evidenced through scanning electron microscopy. Roots developed in agar have shorter hairs, larger rhizodermal cells, and less organized root caps than those growing on paper pulp. In conclusion, it should be noted that in this study, in vitro microporous substrates such as paper pulp lead to the production of similar root hairs to those found in greenhouse peat substrates. Consequently, if agar could be used for micropropagation, rooting, and plant acclimatization, enhancement could be achieved if rooting stage was performed on micro-porous substrates such as paper pulp.
Microbial enzymes have gained interest for their widespread use in various industries and medicine due to their stability, ease of production, and optimization. Endophytic fungi in plant tissues produce a wide range of secondary metabolites and enzymes, which exhibit a variety of biological activities. The present review illustrates promising applications of enzymes produced by endophytic fungi and discusses the characteristic features of the enzymes, application of the endophytic fungal enzymes in therapeutics, agriculture, food, and biofuel industries. Endophytic fungi producing ligninolytic enzymes have possible biotechnological applications in lignocellulosic biorefineries. The global market of industrially important enzymes, challenges, and future prospects are illustrated. However, the commercialization of endophytic fungal enzymes for industrial purposes is yet to be explored. The present review suggests that endophytic fungi can produce various enzymes and may become a novel source for upscaling the production of enzymes of industrial use.
Biosorption on lignocellulosic wastes and by-products has been identified as a proper alternative to the existing technologies applied for toxic metal ion and dye removal from wastewater streams. This paper deals with utilization of typical low cost wastes and by-products produced in different food agricultural and agro-industries as biosorbent and reviews the current state of studies on a wide variety of cheap biosorbents in natural and modified forms. The efficiency of each biosorbent has been also discussed with respect to the operating conditions (e.g. temperature, hydraulic residence time, initial metal concentration, biosorbent particle size and its dosage), chemical modification on sorption capacity and preparation methods, as well as thermodynamics and kinetics. (C) 2013 Elsevier Ltd. All rights reserved.
Lignocellulosic biorefinery processes used to produce bioenergy and value-added products are technologically complex, expensive, energy-demanding, and often not environmentally friendly. Expansion of new value-added products produced in the existing biorefinery is hampered by a lack of efficient and, at the same time, sustainable technologies. Therefore, there is a strong need to develop novel technologies and/or create synergies between existing technologies to convert lignocellulosic biomass into value-added products in a sustainable manner. In this paper, solutions for cascade processes to convert lignocellulosic biomass into value-added products using ionic liquids and lipases are investigated. First, the chemical composition of lignocellulosic biomass and basic principles of solid-state fermentation are summarized. Then, an overview of lipase production by solid-state cultivation of microorganisms on lignocellulosic biomass is given. Additionally, the use of ionic liquids for lignocellulosic biomass valorization is discussed, followed by an overview of lipase-catalyzed biotransformation in ionic liquids in batch reactors and microreactors. At the end, a sustainability assessment of the synthesis of three selected ionic liquids and six lipase-catalyzed biotransformation in ionic liquids was performed using green chemistry metrics.
In the present study, the potential of synthesized mixed cellulose, alginate and hydroxyapatite beads for the efficient removal of Ni (II) and Cu (II) ions from aqueous solutions was investigated. Cellulose, alginate and hydroxyapatite are known for their individual adsorption capacity. Beads were prepared in different ratios of these materials. The prepared beads were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). FTIR and XRD analysis showed characteristic peaks assigned to cellulose, alginate and hydroxyapatite. Thermal stability was observed to increase with increase of hydroxyapatite percentage in beads. SEM images showed increased surface porosity and roughness with the increase of cellulose percentage. The prepared beads were used for the removal of Ni (II) and Cu (II) ions from aqueous solutions and the process was optimized with respect to pH, contact time, adsorbent dose and initial concentration of metal ions. The values of the coefficient of determination (R-2) of the Langmuir and Freundlich adsorption model indicated that the adsorbed Cu (II) and Ni (II) ions form monolayer coverage on the adsorbent surface. In kinetic analysis, Pseudo-second-order model fitted the kinetic experimental data well, as it showed high R-2 value; above 0.9990.
Cellulose nanofibers (CNFs) from banana peels was evaluated as promising stabilizer for oil-in-water emulsions. CNFs were treated using ultrasound and high-pressure homogenizer. Changes on the size, crystallinity index and zeta potential of CNFs were associated with the intense effects of cavitation phenomenon and shear forces promoted by mechanical treatments. CNFs-stabilized emulsions were produced under the same process conditions as the particles. Coalescence phenomenon was observed in the emulsions produced using high-pressure homogenizer, whereas droplets flocculation occurred in emulsions processed by ultrasound. In the latter, coalescence stability was associated with effects of cavitation forces acting on the CNFs breakup. Thus, smaller droplets created during the ultrasonication process could be recovered by particles that acted as an effective barrier against droplets coalescence. Our results improved understanding about the relationship between the choice of emulsification process and their effects on the CNFs properties influencing the potential application of CNFs as a food emulsifier.
Lignocellulosic biomass is a promising feedstock for ethanol production, but lignin, a polyphenol, hampers the use of enzymes for its saccharification; pretreatment is thus key to preparing such feedstock. Ozonation was previously demonstrated as an effective pretreatment, but claimed to be uneconomical due to the assumed need for lignin mineralization. We analyzed, for the first time, ozonation of highly concentrated tannic acid (TA) solution (60 g/L) as a lignin model. Most of the TA disappeared within 3.5 h, following triple-phase kinetics with two transition points: at 7 min and 60 min of ozonation for 0.4 L ozone reactor. Maximal enzymatic activity was found at the first transition point, demonstrating that very short ozonation that results in partial decomposition of TA, is enough to remediate TA's negative effect on cellulase activity. Short ozonation could decrease energy input by up to 97\%, making ethanol production more economically competitive. (C) 2017 Elsevier Ltd. All rights reserved.
Xylans are the major hemicelluloses in grasses, but their effects on biomass saccharification remain unclear. In this study, we examined the 79 representative Miscanthus accessions that displayed a diverse cell wall composition and varied biomass digestibility. Correlation analysis showed that hemicelluloses level has a strong positive effect on lignocellulose enzymatic digestion after NaOH or H2SO4 pretreatment. Characterization of the monosaccharide compositions in the KOH-extractable and non-KOH-extractable hemicelluloses indicated that arabinose substitution degree of xylan is the key factor that positively affects biomass saccharification. The xylose/arabinose ratio after individual enzyme digestion revealed that the arabinose in xylan is partially associated with cellulose in the amorphous regions, which negatively affects cellulose crystallinity for high biomass digestibility. The results provide insights into the mechanism of lignocellulose enzymatic digestion upon pretreatment, and also suggest a goal for the genetic modification of hemicelluloses towards the bioenergy crop breeding of Miscanthus and grasses. (C) 2012 Elsevier Ltd. All rights reserved.
Sustainable growth can be achieved by recycling waste material into useful resources without affecting the natural ecosystem. Among all nanomaterials, carbon nanomaterials from biowaste are used for various applications. The pyrolysis process is one of the eco-friendly ways for synthesizing such carbon nanomaterials. Recently, polymer nanocomposites (PNCs) filled with biowaste-based carbon nanomaterials attracted a lot of attention due to their enhanced mechanical properties. A variety of polymers, such as thermoplastics, thermosetting polymers, elastomers, and their blends, can be used in the formation of composite materials. This review summarizes the synthesis of carbon nanomaterials, polymer nanocomposites, and mechanical properties of PNCs. The review also focuses on various biowaste-based precursors, their nanoproperties, and turning them into proper composites. PNCs show improved mechanical properties by varying the loading percentages of carbon nanomaterials, which are vital for many defence- and aerospace-related industries. Different synthesis processes are used to achieve enhanced ultimate tensile strength and modulus. The present review summarizes the last 5 years' work in detail on these PNCs and their applications.
Maize, also called corn, is one of the most available feedstocks worldwide for lignocellulosic biorefineries. However, a permanent biomass supply over the year is essential for industrial biorefinery application. In that context, ensiling is a well-known agricultural application to produce durable animal feed for the whole year. In this study, ensiled maize was used for steam refining experiments with subsequent enzymatic hydrolysis using the Cellic(R) CTec2 to test the application possibilities of an ensiled material for the biorefinery purpose of fermentable carbohydrate production. Steam refining was conducted from mild (log R-0 = 1.59) to severe conditions (log R-0 = 4.12). The yields were determined, and the resulting fractions were characterized. Hereafter, enzymatic hydrolysis of the solid fiber fraction was conducted, and the carbohydrate recovery was calculated. A conversion to monomers of around 50\% was found for the mildest pretreatment (log R-0 = 1.59). After pretreatment at the highest severity of 4.12, it was possible to achieve a conversion of 100\% of the theoretical available carbohydrates. From these results, it is clear that a sufficient pretreatment is necessary to achieve sufficient recovery rates. Thus, it can be concluded that ensiled maize pretreated by steam refining is a suitable and highly available feedstock for lignocellulosic biorefineries. Ultimately, it can be assumed that ensiling is a promising storage method to pave the way for a full-year biomass supply for lignocellulosic biorefinery concepts.
The increase in the population rate has increased the demand for safe and quality food products. However, the current agricultural system faces many challenges in producing vegetables and fruits. Indiscriminate use of pesticides and fertilizers, deficiency of water resources, short shelf life of products postharvest, and nontargeted delivery of agrochemicals are the main challenges. In this regard, carboxymethyl cellulose (CMC) is one of the most promising materials in the agriculture sector for minimizing these challenges due to its mechanical strength, viscosity, wide availability, and edibility properties. CMC also has high water absorbency; therefore, it can be used for water deficiency (as superabsorbent hydrogels). Due to the many hydroxyl groups on its surface, this substance has high efficacy in removing pollutants, such as pesticides and heavy metals. Enriching CMC coatings with additional substances, such as antimicrobial, antibrowning, antioxidant, and antisoftening materials, can provide further novel formulations with unique advantages. In addition, the encapsulation of bioactive materials or pesticides provides a targeted delivery system. This review presents a comprehensive overview of the use of CMC in agriculture and its applications for preserving fruit and vegetable quality, remediating agricultural pollution, preserving water sources, and encapsulating bioactive molecules for targeted delivery.
The main objective of this research was to evaluate the effects of chemical treatment and sonication (ultrasound) processing on the fiber composition and rumen degradability of date palm seeds (DPS). In the first trial, the effects of incubation or sonication in 4\% sodium hydroxide (NaOH) on DPS fiber content and ruminal degradability were evaluated. Relative to untreated seeds, the ruminal degradability of DPS neutral detergent fiber (NDF) and organic matter (OM) increased (P < 0.05) for the treated seeds and were highest (P < 0.05) for the sonicated seeds. Relative to untreated seeds, the hemicellulose and lignin content were lower (P < 0.05) for the sonicated seeds, while the cellulose content was higher (P < 0.05) for the incubated seeds. In the second trial, the effects of subjecting DPS to different sonication times (5, 10, 20, and 30 min) were evaluated. The degradability of seeds' NDF and OM were greater (P < 0.05) for the sonicated than unsonicated seeds. The highest NDF degradability was seen after 30 min sonication, whereas the OM degradability was not affected by sonication time (P > 0.05). In the third trial, the effects of subjecting DPS to sonication in different NaOH solutions (1\%, 2\%, 4\% NaOH) were evaluated. Relative to untreated seeds, the rumen degradability of seeds' NDF and OM increased with all NaOH concentrations but was highest (P < 0.05) with the 4\% NaOH. In conclusion, our results showed that treating DPS with 4\% NaOH increased the seeds' ruminal degradability, and subjecting DPS to sonication further improved their degradability in the rumen.
This work evaluated the novel application of biochars derived from potassium (K)-rich feedstock (banana peels (BB) and cauliflower leaves (CB)). The sorptive property of the produced biochars was evaluated with multi-element {[
This paper describes the adsorption of cadmium ions from aqueous solution using acrylonitrile (AN)-modified corn stalk (AMCS). AMCS was characterized by elemental analysis, scanning electron microscopy, surface area and porosity analyzer, Fourier transform infrared and solid-state CP/MAS C-13 NMR spectra, and then used to evaluate the adsorption capacity in different pH values, adsorption isotherm, kinetics and thermodynamics in batch experiments. The results showed that AMCS is found to be an effective adsorbent because of its pore size and functional groups (-CN). The pH of 7.0 was an optimal pH for removal of Cd(II) ion and the Langmuir model provides a better fit to the equilibrium data than the Freundlich model, showing a maximum uptake of 12.73 mg g(-1), compared to raw corn stalk (RCS) (3.39 mg g(-1)). Analysis indicated that pseudo-second-order kinetics controlled the adsorption rate. The activation energy (E,) was 9.43 kJ mol(-1). Thermodynamic parameters such as Delta G, Delta H and Delta S were also evaluated to predict the nature of adsorption process. (C) 2009 Elsevier B.V. All rights reserved.
A single-step protocol was developed for the hydrolytic hydrogenation of microcrystalline cellulose into sorbitol over commercial carbon-supported Ru, in the presence of gaseous CO2 as an acid source and molecular hydrogen as a reductant. Under these conditions, cellulose was first hydrolysed to glucose by reversibly formed carbonic acid in water and then instantaneously hydrogenated on Ru/C. By tuning the reaction parameters, such as temperature, time and the relative pressure of CO2 and hydrogen gas, cellulose was fully converted at 220 \& DEG;C in 18 h under 30 and 40 bar of H-2 and CO2, respectively, with a sorbitol yield of 81\%. Blank experiments revealed that without a catalyst and hydrogen, the reaction exhibited <5\% conversion and glucose was the only detected product when the reaction was performed under CO2 pressure. XRD measurements on CO2-treated cellulose surprisingly revealed no noticeable changes in the crystallinity index (<10\% with respect to microcrystalline cellulose), suggesting that hydrolytic hydrogenation took place on crystalline, not amorphous, cellulose. Furthermore, not only several cellulosic feedstocks, including filter paper, cotton wool, and cotton fiber, but also typical cellulose-based wastes such as a cardboard pizza box were also tested and under the optimized conditions sorbitol was obtained with yields ranging from 56\% up to 72\% in all cases. No less significant was the Ru/C catalyst stability, which could be recycled at least six times without any noticeable activity loss.
Packed-bed bioreactors are often used for aerobic solid-state fermentation, since the forced aeration supplies O-2 and removes metabolic heat from the bed. Motivated by the potential for applications in biorefineries, we review studies conducted on packed-bed bioreactors over the last decade, evaluating the insights these studies provide into how large-scale packed beds should be designed and operated. Many studies have used low superficial air velocities and suffer from preferential airflow, such that parts of the bed are not properly aerated. Moreover, some studies have proposed ineffective strategies, such as reversing the direction of the airflow or introducing air through perforated pipes within the bed. Additionally, many studies have used narrow water-jacketed packed-bed bioreactors, but these bioreactors do not reflect heat removal in wide large-scale packed beds, in which heat removal through the side walls makes a minor contribution. Finally, we conclude that, although some attention has been given to characterizing the porosities, water sorption isotherms and volumetric heat and mass transfer coefficients of substrate beds, this work needs to be extended to cover a wider range of solid substrates, and work needs to be done to characterize how these bed properties change due to microbial growth.
The production of fired or stabilized bricks from lignocellulosic biomass ash is thoroughly examined in this article. Bricks are typically made through the high-temperature firing process or by stabilizing the mixture with binders such as lime and cement. These bricks have a large carbon footprint and high levels of grey energy. In many parts of the world, the excessive use of clay as a natural raw material for the production of conventional bricks will lead to its scarcity. The mixing of clay with lignocellulosic ash during brick manufacturing leads to a better and more reliable solution that conserves scarce natural resources and reduces the impact of environmental pollution. This study aims to review the state of the art in the production of bricks based on lignocellulosic ashes and their physical, thermal, and mechanical properties. The most recent data in the literature related to the manufacture of lignocellulosic ash-based bricks either by firing, cementing or geopolymerization, the design of mixtures, as well as the identification of the main factors influencing the performance and durability of these bricks are presented and discussed. Despite extensive research, there is still very little commercial use of waste bricks in general and lignocellulosic biomass ash in particular. Various toxicity issues of lignocellulosic ash used in brick production limit their use on an industrial scale due to a lack of appropriate standards. In order to achieve practical production of bricks from lignocellulosic ash, research is still needed on standardizing and sustaining biomass ash recycling.
Scarcity of raw materials, reduction of greenhouse gas emissions and reduction of waste disposal in landfills are leading to the development of more sustainable building materials. Based on these lines, this work studies the incorporation of biomass bottom ashes into ceramic materials for brick manufacture, in order to reuse this currently unused waste and reduce clay extraction operations. To this end, different groups of samples were made with different combinations of clay and biomass bottom ashes, from 100\% clay to 100\% biomass bottom ashes. These samples were shaped, sintered and subjected to the usual physical tests in ceramics. In turn, the mechanical resistance, color and leaching of the contaminating elements present were studied. The physical and mechanical tests showed that the results of all the families were adequate, achieving compressive strengths of over 20 MPa and leaching of the contaminating elements acceptable by the regulations. Therefore, a sustainable range of ceramics was developed, with specific properties (porosity, density, resistance and color), with a waste that is currently unused and sustainable with the environment.
In efforts to lower the cost of total conversion of lignocellulosic materials, utilization of hemicellulose must be considered. White-rot fungusPhlebiasp. MG-60 can produce ethanol directly from cellulose and has fermentation ability for glucose, cellulose, and xylose. Therefore, white-rot fungi can be considered a good candidate for consolidated bioprocessing to give bioethanol from lignocellulosic biomass, although little information is available on the direct fermentation of xylan. In the present study, somePhlebiaspecies were selected as candidates because of their ability to ferment xylose to ethanol more efficiently thanPhlebiasp. MG-60. This process indicated that the basidiomycetes that can produce ethanol from xylose are closely related genetically within thePhlebiagenus. The selectedPhlebiaspecies showed higher ethanol productivity from corn core and beechwood xylans thanPhlebiasp. MG-60. The ethanol yields from corn core xylan in culture withPhlebia acerinaHHB11146,Phlebia ludovicianaHHB9640, andPhlebia subochraceaHHB8494 were 46.2\%, 46.7\%, and 39.7\% of theoretical maximum, and those from beechwood xylan were 19.09\%, 17.7\%, and 21.4\% of the theoretical maximum, respectively.
Abrupt urbanization and industrialization around the world resulted in elevated environmental pollution and depletion of natural energy resources. An eco-friendly and economical alternative for energy production is the need of an hour. This can be achieved by converting the waste material into energy. One such waste is lignocellulosic agricultural residues, produced in billions of tons every year all around the world, which can be converted into bioethanol. The main challenge in this bioconversion is the recalcitrant nature of lignocellulosic material. The removal of cementing material is lignin and to overcome the potential inhibitors produced during the disintegration of lignin is the challenging task for biotechnologist. This task can be achieved by a number of different methods but laccase is the most effective and eco-friendly method that can be used for effective removal of lignin along with the increase the accessibility of cellulose and bioethanol yield.
Nanocellulose producing from wood pulp and its derivatives is a well-known and characterized industrial process. However, agro-industrial residues can also be used for this process as they have a high content of lignocellulosic portions, particularly cellulose. Usually discarded or used as animal feed their composition pose a great potential for the generation of value added products. As an alternative to wood pulp, cellulose from residues represent a great source for obtaining nanocellulose due to its wide availability and low cost. Given that many other studies have focused on generating nanocellulose out of wood pulp due to its intrinsic characteristics, such as high aspect ratio, biodegradability, and good overall mechanical properties, it was decided to characterize the processing of agro-industrial residues on last decade in this review as their composition greatly varies among plant sources, presenting influence on produced nanocrystals quality. The intrinsic properties of nanocellulose justify its utilization in many applications, including use in food, cosmetic, and material industry. This review attempts to follow through the state-of-art for crystalline nanocellulose preparation, presenting its current concerns in process and commercial viability, and finally, indicating some future perspectives on using agro-industrial residues as an environmentally-friendly alternative to wood sources. {[
This work evaluates the potential use of 2-hydroxy ethylammonium-based protic ionic liquids (PILs) for dissolving the major lignocellulosic biopolymers such as cellulose, xylose and lignin. Three PILs, 2-hydroxy ethylammonium formate (2-HEAF), 2-hydroxy ethylammonium acetate (2-HEAA) and 2-hydroxy ethylammonium propionate 2-HEAPr, were synthesized and characterized (viscosity, density and conductivity). A small amount of biopolymer was added to the PILs; the biopolymers' dissolution curves were determined from 30 degrees C up to 100 degrees C on these solvents using a hot stage coupled to an optical microscope. The results show that while xylose and lignin could be dissolved by the PILs, cellulose could not, and also that 2-HEAF-which presented the higher ionicity-was the most appropriate PIL among those tested to dissolve these biopolymers (xylose and lignin). They also show that lignin dissolution is faster when an anion with a short alkyl carbon chain is used and that higher heating rates require a somewhat higher temperature to achieve full dissolution. Graphic abstract
The growth of Debaryomyces nepalensis on mixed substrates in batch culture follows diauxic pattern of completely utilizing glucose during the first exponential growth phase, followed by an intermediate lag phase and a second exponential growth phase consuming xylose. The present study deals with the development of a cybernetic mathematical model for prediction of xylitol production in the presence of co-substrate. To experimentally validate the model, defined media supplemented with different concentration of co-substrate were tested and compared with production on single carbon source. High xylitol yield of 0.73 g g(-1) was achieved when supplemented with 10 g L(-1)of glucose in the xylose-rich media. The proposed model could adequately describe the diauxic growth, sequential utilization of substrates and production of xylitol under various ratio of co-substrate. The model could be used as a tool to assess the influence of co-substrate (glucose) concentration added to the media on xylitol production.
A novel process of enzyme pretreatment and semi-simultaneous saccharification and fermentation (SSSF) was developed in this work to improve succinic acid (SA) productivity from duckweed (Landoltia punctata) and achieve low viscosity. Viscosity (83.86\%) was reduced by the pretreatment with combined enzymes at 50 degrees C for 2 h to a greater extent than that by single enzyme (26.19-71.75\%). SSSF was an optimal combination with 65.31 g/L of SA content, which was remarkably higher than those obtained through conventional separate hydrolysis and fermentation (62.12 g/L) and simultaneous saccharification and fermentation (52.41 g/L). The combined approach was effective for SA production. Approximately 75.46 g/L of SA content with a yield of 82.87\% and a productivity of 1.35 g/L/h was obtained after 56 h in a 2 L bioreactor. Further studies will focus on increasing the working scale of the proposed method.
The economic impact of different potentially scalable process improvements was here assessed for the first time in the specific context of a Eucalyptus wood biorefinery producing biofuels, high-value chemicals and energy. The base case scenario referring to bioethanol as the only product was clearly unviable, which mostly resulted from the high cost of cellulases and heat transfer utilities and the moderate final ethanol titers. By supplementing cheese whey to eucalyptus wood hydrolysis, ethanol production increased 51\% leading to a notable improvement on the NPV, from -14.4 to -3.4 M\$. Similarly, when an additional section was included for the recovery of XOS present in the autohydrolysis liquor, the operating costs raised 36\% but annual revenues increased around 5 M\$, resulting in a very solid NPV of 18.9 M\$. Internally burning the final stillage led to savings of 98\% on lowpressure steam consumption and an additional electricity revenue, both contributing to a more economic scenario. One final scenario consisted on the simultaneous integration of all process variations, referring to a complex facility producing not only ethanol but also XOS and energy. This integrated process provided the best economic output, which was translated on a noticeable reduction of the minimum ethanol selling price from 4.88 \$/gal (Base case) to 0.76 \$/gal, and thus confirming the critical role of adopting biorefinery schemes for an economic utilization of lignocellulosic materials.
Porous cellulose spheres (PCS) were fabricated by precipitating the spheres from a cellulose ionic liquid solution, followed by freezing, solvent exchange, and drying. PCS had low crystallinity and a large surface area that facilitated modification with trisodium trimetaphosphate (STMP) to introduce phosphate ester groups into the porous structure of the heterogeneous system. The STMP-modified PCS (SPCS) were used to remove heavy metal ions from aqueous solution. With increasing STMP dosage, the adsorption capacity of SPCS obviously improved due to chelation between Pb2+ and phosphate ester groups. The Idnetic adsorption and isotherm data matched the pseudo-second order model and the Langmuir model well. The maximum adsorption capacity reached 150.6 mg g(-1) for SPCS. SPCS were competitive with other absorbents because the phosphate ester groups and porous structure contributed to Pb2+ adsorption. Moreover, SPCS can be regenerated with ethylenediamine tetraacetic acid disodium salt (EDTA) solution for repetitious adsorption of Pb2+. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.
The present study evaluates the effect of moisture in low-temperature and ultrasound pretreatment on lignocellulosic substrates anaerobic biodegradability, where brewer's spent grain was used as model substrate. Besides moisture content, low-temperature pretreatment was also evaluated in terms of temperature (60-80 degrees C) and exposure time (12-72 h). Likewise, ultrasonication was also evaluated in terms of specific energy (1000-50,000 kJ kgTS(-1)). In addition, the effect of substrate particle size reduction by milling pretreatment was also considered. The results clearly demonstrated that substrate moisture (total solid concentration) is a significant parameter for pretreatment performance, although it has been rarely considered in pretreatment optimisation. Specifically, moisture optimisation increased the methane yield of brewer's spent grain by 6\% for low-temperature pretreatment (60 degrees C), and by 14\% for ultrasound pretreatment (1000 kJ kgTS(-1)) towards the control (without pretreatment). In both pretreatments, the experimental optimum total solid concentration was 100 gTS kg(-1). Thus, lowering substrate moisture, a strategy suggested attaining energetic pretreatment feasibility, needs to be analysed as another pretreatment variable since it might have limited correlation. Finally, a preliminary energetic balance of the pretreatments under study showed that the extra methane production could not cover the energetic pretreatment expenses. (C) 2015 Elsevier Ltd. All rights reserved.
Understanding the mechanisms involved in tolerance to inhibitors is the first step in developing robust yeasts for industrial second-generation ethanol (E2G) production. Here, we used ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and MetaboAnalyst 4.0 for analysis of MS data to examine the changes in the metabolic profile of the yeast Spathaspora passalidarum during early fermentation of hemicellulosic hydrolysates containing high or low levels of inhibitors (referred to as control hydrolysate or CH and strategy hydrolysate or SH, respectively). During fermentation of SH, the maximum ethanol production was 16 g L-1 with a yield of 0.28 g g(-1) and productivity of 0.22 g L-1 h(-1), whereas maximum ethanol production in CH fermentation was 1.74 g L-1 with a yield of 0.11 g g(-1) and productivity of 0.01 g L-1 h(-1). The high level of inhibitors in CH induced complex physiological and biochemical responses related to stress tolerance in S. passalidarum. This yeast converted compounds with aldehyde groups (hydroxymethylfurfural, furfural, 4-hydroxybenzaldehyde, syringaldehyde, and vanillin) into less toxic compounds, and inhibitors were found to reduce cell viability and ethanol production. Intracellularly, high levels of inhibitors altered the energy homeostasis and redox balance, resulting in lower levels of ATP and NADPH, while that of glycolytic, pentose phosphate, and tricarboxylic acid (TCA) cycle pathways were the most affected, being the catabolism of glucogenic amino acids, the main cellular response to inhibitor-induced stress. This metabolomic investigation reveals interesting targets for metabolic engineering of ethanologenic yeast strains tolerant against multiple inhibitors for E2G production.
This paper presents a state-of-the-art review of research on the utilization of fibers (predominantly derived from waste materials) as reinforcement in adobe brick production. Recycling of these wastes provides sustainable construction materials and helps to protect the environment. Specimen preparation and test procedures are outlined. The effects of addition of these wastes on the physical and mechanical properties of adobe bricks as presented in the literature, are investigated. The main results for each additive are presented and discussed. It is concluded that improved adobe brick properties can be expected with the addition of combination of waste additives. The use of waste materials in the construction industry is generally of interest and useful for engineers and designers seeking sustainable solutions in construction. It is also of interest to researchers actively seeking to develop methodical approaches to quantifying, optimising and testing the performance in use of such waste material additives.
We may currently observe an important trend in the search for environmentally friendly renewable resources. Biomass is undoubtedly a source of such material. An especially valuable by-product of the paper industry is lignin - a biopolymer with a unique chemical structure. The controlled activation or modification of lignin can be used to generate components with designed properties. Additionally, lignin can be activated using green solvents - represented by ionic liquids - to generate materials for the design of polymer composites and pro-ecological abrasive materials. Another interesting area of application is active platforms for biosensors. Use has also been made of lignin and its derivatives in the removal of environmentally toxic metals and certain organic compounds (herbicides, phenol and its derivatives, pharmacologically active substances) from wastewater. This review emphasizes recent advances in the use of ionic liquids to dissolve or activate lignin. A significant contribution is represented by the material concerning the design of hybrid systems with the use of lignin treated with ionic liquids. New directions of development in the field are also indicated. (C) 2020 Elsevier B.V. All rights reserved.
Starch was isolated from three Andean-native crops - arracacha (Arracacia xanthorrhiza), oca (Oxalis tuberosa), and sweet potato (Ipomoea batatas) - for use as a raw material for the production of foam trays. The starches were characterized in their proximal composition, crystallinity, microstructure and thermal properties. The sweet potato starch showed the highest amylose content (42.65\%) and the lowest protein content (0.30\%). The oca starch granules were larger (10-30 mu m) than sweet potato and arracacha starch. The highest crystallinity of sweet potato starch caused larger values of onset temperature (To), peak temperature (Tp), conclusion temperature (Tc) (67.64 degrees C, 72.83 degrees C, and 81.20 degrees C, respectively) than arracacha and oca starch. The novel foam trays showed good appearance, adequate expansion, and low density; however, all foam trays showed a water absorption capacity >50\%, which was related to their porosity and low density. Also, sweet potato and oca starch trays showed high tensile strength (0.67 and 0.65 MPa, respectively) compared with arracacha starch trays (0.52 MPa). (C) 2018 Elsevier B.V. All rights reserved.
Converting xylan from the hemicellulosic fraction of lignocellulose into xylooligosaccharides (XOS) has attracted intense research focus in the recent years for obtaining high added-value products. These XOS are emerging prebiotic compounds that present significant functional properties. This paper reviewed the current status of lignocellulosic pretreatments and the CAZymes hydrolysis of xylan, investigating the previously reported alternatives and enzymes. The evaluation criteria and parameters for XOS production processes, which can differ significantly between studies, are also reported. For example, one study may focus on the cost of production, while another may focus on the environmental impact. Most generally, however, XOS are produced in two stages through acid pretreatment and enzymatic hydrolysis. This process is known to be highly effective, and it yields a product that is rich in nutrients and beneficial for many purposes. This two-stage production process is also easy to regulate and control, which makes it an ideal method of production when looking to create a high-quality XOS product. Throughout this work, we discuss relevant topics that should be considered when exploring the enzymatic production of XOS, including strategies for producing XOS by CAZymes and the evaluation of the prebiotic effects of XOS on the gut microbiota.
This review aims to present an analysis and discussion on the processing of lignocellulosic biomass in terms of biorefinery concept and circular bioeconomy operating at high solids lignocellulosic (above 15\% {[
Due to the growing demand for natural carotenoids, researchers have been searching for strains that are capable of efficient synthesis of these compounds. This study tested 114 red yeast strains collected from various natural environments and food specimens in Poland. The strains were isolated by their ability to produce red or yellow pigments in rich nutrient media. According to potential industrial significance of the carotenoids, both their total production and share of individual carotenoids (ss-carotene,gamma-carotene, torulene, and torularhodin) were analyzed. The total content of carotenoid pigments in the yeast dry matter ranged from 13.88 to 406.50 mu g/g, and the percentages of individual carotenoids highly varied among the strains. Most of the yeast isolates synthesized torulene at the highest amount. Among the studied strains, isolates with a total carotenoid content in biomass greater than 200 mu g/g and those containing more than 60\% torularhodin were selected for identification (48 strains). The identified strains belonged to six genera: Rhodotorula, Sporidiobolus, Sporobolomyces, Buckleyzyma, Cystofilobasidium, and Erythrobasidium. The largest number of isolates belonged to Rhodotorula babjevae (18), Rhodotorula mucilaginosa (7), Sporidiobolus pararoseus (4), and Rhodotorula glutinis (4).
Due to the continuous rise in population, modernization, and industrialization, the demand for energy is increasing day by day, resulting in serious issues such as fossil fuel depletion, pollution, and power shortages. As a result, there is an urgent need to investigate alternate energy sources. Lignocellulosic biomass pyrolysis has been shown as the most promising feedstock for the production of sustainable and renewable biofuels. Unfor-tunately, the fuel characteristics of bio-oil generated from biomass pyrolysis are still insufficient to meet pe-troleum products ASTM standards. To address these challenges, co-pyrolysis of lignocellulosic biomass with other carbonaceous materials (e.g., plastic waste, Tyre garbage etc.) is emerging as one of the most promising approaches. Various experimental studied have been conducted on lignocellulosic biomasses co-pyrolysis with other carbonaceous materials such as plastic waste, tire waste, coal, algae and sewage sludge. The present manuscript aims to review and establish the scope of co-pyrolysis of lignocellulosic biomass with various carbon rich feedstocks for renewable production of high-quality renewable fuels. The synergistic effect between ligno-cellulosic biomass and other carbonaceous materials has been explored in detail. Furthermore, recent advances in co-pyrolysis process along with the reaction affecting parameters are also summarized in brief. Consequently, this review demonstrates both highlights of the remarkable achievement of co-pyrolysis and the milestones that are necessary to be garnered in the future.
The present research aimed to develop natural rubber hybrid composites reinforced with treated ultrafine calcium carbonate/carbon black (CC/CB). The influence of CC/CB with various filler ratios (50/0, 40/10, 30/20, 20/30, 10/40 and 0/50) on mechanical properties and cure characteristics of the composites was investigated. Also filler reinforcing efficiency was compared aiming to achieve the best ratio for CB partial substitution as compared to composites with CC and CB incorporated separately. The CC30/CB20 composites reached around 17.56 +/- 0.3 MPa similar strength at break response compared to CC0/CB50 (16.83 +/- 0.6 MPa). Elongation at break increased 48\% in relation to CC0/CB50. Hardness maintained similar values compared to high concentration of CB composites. The increase of crosslink density is attributed to a strong interaction between CC and CB and showed a synergism between filler and polymeric matrix in hybrid composites. Scanning electron microscopy studies also reveal a good filler dispersion between filler particles and matrix. The results shown that the new material can be an alternative filler for partial substitution of CB conserving mechanical properties.
Sago frond is a lignocellulose waste that it has not been utilized optimally. The purpose of this study was to produce cellulose from sago frond with alkaline delignification and bleaching on various types of bleach agents. The study was conducted in three stages, namely a characterization of sago frond, alkaline delignification, and bleaching. Proximate analysis showed that sago fronds are potentially used as a cellulose source. The treatments of alkaline delignification and bleaching on various types of bleach agents significantly affected the characteristics of cellulose. The delignification using 10\% NaOH for 2 h, after which the bleaching was carried out using the alkaline hydrogen peroxide for the same duration, thereby, producing cellulose of the highest degree of crystallinity and whiteness, while the hemicellulose and lignin contents were relatively low. Thus, sago frond has the potential to be used as a cellulose source and is widely applied.
Homogeneous modification of cellulose with succinic anhydride was performed using tetrabutylammonium acetate (TBAA)/dimethyl sulfoxide (DMSO) mixed solvent. The molar ratio of succinic anhydride (SA) to free hydroxyl groups in the anhydroglucose units (AGU), TBAA dosage, reaction temperature, and reaction time were investigated. The highest degree of substitution (DS) value of 1.191 was obtained in a 10 wt\% TBAA/DMSO mixed solvent at 60 degrees C for 60 min, and the molar ratio of SA/AGU was 6/1. The molar ratio of SA/AGU and the TBAA dosage showed a significant influence on the reaction. The succinoylated cellulose was characterized by ATR-FTIR, TGA, XRD, solid state CP/MAS C-13 NMR spectroscopy (CP/MAS C-13 NMR), and SEM. Moreover, the modified cellulose was applied for the adsorption of Cu2+ and Cd2+, and both the DS values of modified cellulose and pH of the heavy metal ion solutions affected the adsorption capacity of succinylated cellulose. The highest capacity for Cu2+ and Cd2+ adsorption was 42.05 mg/g and 49.0 mg/g, respectively.
The rapid growth in urbanization and construction is increasing the demand for cement and aggregate, especially for concrete production. However, the production of cement and concrete increases the emission of carbon dioxide, and the source of natural aggregates to deplete. Hence, alternative materials are needed for concrete applications. Wood waste ash (WWA), a substitute material, is obtained from woodfired plants, pulp and paper, and other wood-burning industrial facilities. However, the WWA production industry requires large areas of land in localities. Some wood waste is spread over the land, while some industries burn wood waste in incinerators, thus promoting air pollution, a major environmental issue. This paper provides a comprehensive review on the effective use of WWA as a replacement material for cement or aggregates in concrete. An overview of the utilization of WWA in the construction sector is presented, and development trends are studied in accordance with setting time, strength, and durability properties. Meanwhile, the effects of WWA as a pozzolanic additive are summarized for ecoconcreting applications. Findings show that incorporating WWA in cement and concrete is beneficial to sustainable development and zero-waste technology. Environmental issues on using WWA and ways of reducing the hazardous impact on the surroundings are presented as well. (C) 2019 Elsevier Ltd. All rights reserved.
Background: Pretreatments are one of the main bottlenecks for the lignocellulose conversion process and the search for cheaper and effective pretreatment methodologies for each biomass is a complex but fundamental task. Here, we used a 2.5-1 fractional factorial design (FFD) to optimize five pretreatment variables: milling time, temperature, double treatment, chemical concentration, and pretreatment time in acid-alkali (EA) and acid-organosolv (EO) pretreatments, applied to elephant grass leaves. Results: FFD allowed optimization of the pretreatment conditions using a reduced number of experiments and allowed the identification of secondary interactions between the factors. FFD showed that the temperature can be kept at its lower level and that the first acid step can be eliminated in both pretreatments, without significant losses to enzymatic hydrolysis. EA resulted in the highest release of reducing sugars (maximum of 205 mg/g substrate in comparison to 152 mg/g in EO and 40 mg/g in the untreated sample), using the following conditions in the alkali step: {[
Glycolipids, consisting of a carbohydrate moiety linked to fatty acids, are microbial surface active compounds produced by various microorganisms. They are characterized by high structural diversity and have the ability to decrease the surface and interfacial tension at the surface and interface, respectively. Rhamnolipids, trehalolipids, mannosylerythritol lipids and cellobiose lipids are among the most popular glycolipids. They have received much practical attention as biopesticides for controlling plant diseases and protecting stored products. As a result of their antifungal activity towards phytopathogenic fungi and larvicidal and mosquitocidal potencies, glycolipid biosurfactants permit the preservation of plants and plant crops from pest invasion. Also, as a result of their emulsifying and antibacterial activities, glycolipids have great potential as food additives and food preservatives. Furthermore, the valorization of food byproducts via the production of glycolipid biosurfactant has received much attention because it permits the bioconversion of byproducts on valuable compounds and decreases the cost of production. Generally, the use of glycolipids in many fields requires their retention from fermentation media. Accordingly, different strategies have been developed to extract and purify glycolipids. (C) 2016 Society of Chemical Industry
This review discussed the last 10 years progress in the use of lignocellulosic materials chemically modified as low-cost biosorbents. Thus, the chemical modifications, such as chemical pretreatment, oxidation, as well as the grafting of carboxyl groups, amines, amides, etc., on lignocellulosic fibers, that aim to increase the number of adsorption sites and maximize toxic metal ion adsorption capacity have been addressed. The literature presents results that indicated performances of biosorbents equal to or even higher than conventional methods and adsorbents. Many efforts have been concentrated on the improvements of these biosorbents through chemical modifications. However, some difficulties still exist, including the discharge of colored organic compounds resulting from the pretreatments and the development of fast, clean, and low-cost synthesis of selective and multifunctional adsorbents. Thus, the challenge for future research is to find solutions to these difficulties in order to finally make lignocellulosics biosorbents that can replace conventional adsorbent materials. (c) 2015 Wiley Periodicals, Inc.
Microalgae-derived lipids are good sources of biofuel, but extracting them involves high cost, energy expenditure, and environmental risk. Surfactant treatment to disrupt Scenedesmus biomass was evaluated as a means to make solvent extraction more efficient. Surfactant treatment increased the recovery of fatty acid methyl ester (FAME) by as much as 16-fold vs. untreated biomass using isopropanol extraction, and nearly 100\% FAME recovery was possible without any Folch solvent, which is toxic and expensive. Surfactant treatment caused cell disruption and morphological changes to the cell membrane, as documented by transmission electron microscopy and flow cytometry. Surfactant treatment made it possible to extract wet biomass at room temperature, which avoids the expense and energy cost associated with heating and drying of biomass during the extraction process. The best FAME recovery was obtained from high-lipid biomass treated with Myristyltrimethylammonium bromide (MTAB)- and 3-(decyldimethylammonio)-propanesulfonate inner salt (3\_DAPS)-surfactants using a mixed solvent (hexane : isopropanol = 1 : 1, v/v) vortexed for just 1 min; this was as much as 160-fold higher than untreated biomass. The critical micelle concentration of the surfactants played a major role in dictating extraction performance, but the growth stage of the biomass had an even larger impact on how well the surfactants disrupted the cells and improved lipid extraction. Surfactant treatment had minimal impact on extracted-FAME profiles and, consequently, fuel-feedstock quality. This work shows that surfactant treatment is a promising strategy for more efficient, sustainable, and economical extraction of fuel feedstock from microalgae.
Zymomonas mobilis is a well-recognized ethanologenic bacterium with outstanding characteristics which make it a promising platform for the biotechnological production of relevant building blocks and fine chemicals compounds. In the last years, research has been focused on the physiological, genetic, and metabolic engineering strategies aiming at expanding Z. mobilis ability to metabolize lignocellulosic substrates toward biofuel production. With the expansion of the Z. mobilis molecular and computational modeling toolbox, the potential of this bacterium as a cell factory has been thoroughly explored. The number of genomic, transcriptomic, proteomic, and fluxomic data that is becoming available for this bacterium has increased. For this reason, in the forthcoming years, systems biology is expected to continue driving the improvement of Z. mobilis for current and emergent biotechnological applications. While the existing molecular toolbox allowed the creation of stable Z. mobilis strains with improved traits for pinpointed biotechnological applications, the development of new and more flexible tools is crucial to boost the engineering capabilities of this bacterium. Novel genetic toolkits based on the CRISPR-Cas9 system and recombineering have been recently used for the metabolic engineering of Z. mobilis. However, they are mostly at the proof-of-concept stage and need to be further improved.
Solar biomass hybridization is a promising energy technique for efficient utilization while mitigating the disadvantages associated with both biomass and solar energy source. In conventional concentrating solar power (CSP) systems, the contribution of solar energy is relatively low, merely supplementing the system with low/ medium temperature air/steam. This paper aimed to emphasize the improvement of solar heat share, particularly in the topping cycle of the hybrid system. The solar aided processes, either directly generating superheated air/ steam or direct gasification are thermodynamically favorable at very high temperatures, in excess of 800 degrees C. Unfortunately, this temperature is unattainable in conventional CSP systems using molten salt. Accordingly, the integration of solar power tower (SPT) with solid particle fluidized system in a beam down configuration has been proposed for the hybrid solar-biomass systems. Studies of such integration system presented challenges in terms of operating temperature, continuous supply/syngas production and scaling of reactor, particularly for circulating fluidized bed (CFB). The selection of solid particle and gas flow rate are among the governing parameters for high operating temperature and effective utilization of solar heat. The development of high temperature hybrid solar-biomass system is anticipated for higher solar-to-fuel conversion efficiencies, minimizing the direct combustion of biomass and reduce the emission of greenhouse gas (GHG) emissions.
In this work, we investigated in vitro the antioxidant, cytotoxic and anti-leishmanial activities of a lignin extracted from the leaves of Morinda citrifolia. Initially, an analysis of the composition of the sheets was performed, then the lignin was obtained by alkaline delignification and characterized by different techniques: elemental analysis, FT-R, UV-vis, HSQC-NMR, thermal analysis, Py-GC/MS and by GPC. The results showed that the leaves had in their composition cellulose (31.29\%), hemicellulose (25.01\%), lignin (18.34\%), extractives (14.39\%) and ash (10.03\%). The lignin extraction yield was 89.8\%. The lignin obtained is of the GSH type with the following contents 79.39\%, 13.58\% and 7.03\% respectively. Furthermore, it is low molecular weight and thermally stable. It had a phenolic content of 93.3 mg GAE/g and low antioxidant activity. In macrophage cytotoxicity assays, it presented a CC50 of 31.0 mu g/mL, showing less toxicity than amphotericin B. In assays against the promastigote forms of Leishmania amazonensis, lignin presented an IC50 of 29.56 mu g/mL, a less effective concentration than amphotericin B (IC50 = 0.14 mu g/mL). However, it was able to promote inhibition of the parasites, a fact confirmed by structural changes. These findings reinforce that M. citrifolia lignin is a promising macromolecule for use as an antiparasitic and antioxidant agent.
The capacity of different Bacillus species to produce large amounts of extracellular enzymes and ability to ferment various substrates at a wide range of pH and temperature has placed them among the most promising hosts for the industrial production of many improved and novel products. The global interest in prebiotics, for example, xylooligosaccharides (XOs) is ever increasing, rousing the quest for various forms with expanded productivity. This article provides an overview of xylanase producing bacilli, with more emphasis on their capacity to be used in the production of the XOs, followed by the purification strategies, characteristics and application of XOs from bacilli. The large-scale production of XOs is carried out from a number of xylan-rich lignocellulosic materials by chemical or enzymatic hydrolysis followed by purification through chromatography, vacuum evaporation, solvent extraction or membrane separation methods. Utilization of XOs in the production of functional products as food ingredients brings well-being to individuals by improving defense system and eliminating pathogens. In addition to the effects related to health, a variety of other biological impacts have also been discussed.
Biochar as soil amendment can increase soil carbon (C) sequestration and mineral nutrients; however, some of its soluble elements may also be unintentionally released during the application. In this work, eight types of biochars were derived from herbaceous, woody, and waste (tailing, manure, sludge) biomass feedstocks through slow pyrolysis at 600 A degrees C in N-2. The elemental composition, specific surface area, morphology, crystalline phases, thermal stability, surface functional groups, and pH of the point of zero charge of the biochars were determined using various methods. These properties varied significantly among the tested biochars, suggesting that feedstock type played an important role in controlling their properties. Laboratory release and toxicity characteristic leaching procedure extraction experiments were conducted to evaluate the potential release of nutritious and toxic element from biochars. Results showed that all the biochars released nutritious elements and thus, may be beneficial to plants when amended in soils. In general, biochars produced from herbaceous and woody biomass feedstocks showed low risks of releasing toxic elements. Biochar derived from sludge, however, might present ecotoxicological challenges for its environmental applications due to the release of toxic elements, such as heavy metals.
At present time, every nation is absolutely concern about increasing agricultural production and bioremediation of petroleum-contaminated soil. Hence, with this intention in the current study potent natural surfactants characterized as lipopeptides were evaluated for low-cost production by Bacillus subtilis SNW3, previously isolated from the Fimkessar oil field, Chakwal Pakistan. The significant results were obtained by using substrates in combination (white beans powder (6\% w/v) + waste frying oil (1.5\% w/v) and (0.1\% w/v) urea) with lipopeptides yield of about 1.17 g/L contributing 99\% reduction in cost required for medium preparation. To the best of our knowledge, no single report is presently describing lipopeptide production by Bacillus subtilis using white beans powder as a culture medium. Additionally, produced lipopeptides display great physicochemical properties of surface tension reduction value (SFT= 28.8 mN/m), significant oil displacement activity (ODA =4.9 cm), excessive emulsification ability (E24=69.8\%), and attains critical micelle concentration (CMC) value at 0.58 mg/mL. Furthermore, biosurfactants produced exhibit excellent stability over an extensive range of pH (1-11), salinity (1-8\%), temperature (20-121 degrees C), and even after autoclaving. Subsequently, produced lipopeptides are proved suitable for bioremediation of crude oil (86\%) and as potent plant growth-promoting agent that significantly (P < 0.05) increase seed germination and plant growth promotion of chili pepper, lettuce, tomato, and pea maximum at a concentration of (0.7 g/100 mL), showed as a potential agent for agriculture and bioremediation processes by lowering economic and environmental stress.
Fractionation of lignocellulose is a fundamental step in the valorization of cellulose, hemicelluloses, and lignin to produce various sustainable fuels, materials and chemicals. Strong alkaline fractionation is one of the most applied processes since the paper industry has been using it for more than a century, and the mineral acid fractionation process is currently the most applied for the production of cellulosic ethanol. However, in the last decade, mild alkaline fractionation has been becoming increasingly widespread in the frame of cellulosic ethanol biorefineries. It leads to the solubilization of hemicelluloses and lignin at various extent depending on the conditions of the extraction, whereas the cellulose remains insoluble. Some studies showed that the cellulose saccharification and fermentation into ethanol gave higher yields than the mineral acid fractionation process. Besides, contrary to the acid fractionation process, the mild alkaline fractionation process does not hydrolyze the sugar polymers, which can be of interest for different applications. Lignocellulosic mild alkaline extracts contain hemicelluloses, lignin oligomers, phenolic monomers, acetic acid, and inorganic salts. In order to optimize the economic efficiency of the biorefineries using a mild alkaline fractionation process, the purification of the alkaline extract to valorize its different components is of major importance. This review details the conditions used for the mild alkaline fractionation process and the purification techniques that have been carried out on the obtained hydrolysates, with a focus on the yields and purities of the different compounds.
In the recent past, an increasing interest is mostly observed in using microwave and ultrasonic irradiation to aid the biological conversion of waste materials into value-added products. This study is focused on various individual impacts of microwaves and ultrasonic waves for the treatment of biomass before the synthesis of value-added products. Following, a comprehensive review of the mechanisms governing microwaves and ultrasonication as the treatment methods, their effects on biomass disruption, solubilization of organic matter, modification of the crystalline structure, enzymatic hydrolysis and production of reducing sugars was performed. However, based on the lab-scale experiments evaluated, microwaves and ultrasonication were studied to be economically and energetically ineffective despite their beneficial effects on the waste biomass. This article reviews some of the difficulties associated with using microwaves and ultrasonic irradiation for the efficient processing of waste biomasses and identified some potential directions for future study.
Cupuacu husk (CH) is the waste of a common fruit from a native species of the Brazilian Legal Amazon. The current study investigated the influence of ultrasound (US) combined with aqueous, acid, alkaline, and ionic liquid (IL) pretreatments on the chemical and physical aspects of CH and the yield of chemical platforms production, 5-hydroxymethylfurfural (HMF) and furfural (FF), using IL. Scanning electron microscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy were used to feature the raw and pretreated biomass. The highest levels of glucose (9.90 g L-1) were observed in the liquid fraction resulting from the acid + US pretreatment followed by acid hydrolysis. The IL + US pretreatment recorded the best performance in removing lignin. Based on XRD analyses, ultrasound increased crystallinity of all pretreated samples as a result of the removal of cellulose's amorphous fraction. However, it promoted accessibility to adopted reagents by increasing biomass exposure due to cavitation. The best yields of HMF and FF were recorded from hydrolysis of the solid fraction resulting from the acid + US (12.94\%) and alkaline + US (48.84\%) pretreatment, respectively. These results indicate satisfactory performance of ultrasound assisted pretreatments to the simplified and economic conversion of biomass into value-added products.
Activated carbon of babassu coconut mesocarp (ACB), which is an environment-friendly material (low-cost), was evaluated as alternative adsorbent for the adsorption and desorption of acetylsalicylic acid (ASA) from aqueous solution. ASA is a non-steroidal anti-inflammatory pharmaceutical easily acquired and prescribed worldwide, and not completely removed by wastewater treatment plants (WWTPs). For this reason, properties of ACB (untreated) were characterized by N-2 adsorption/desorption, FTIR spectroscopy, SEM, Boehm titration method and pH(PZC). The microporous nature of ACB strongly influenced both the adsorption of ASA and the occurrence of physical adsorption bonds, which allows the reversibility of the reaction. ACB surface was rich in carboxylic and phenolic groups. The adsorption was best described by the pseudo-second order kinetic model (89.87 mg g(-1)) at pH 2.0, which represented 80\% of ACB adsorption capacity. Conversely, desorption was best represented by pseudo-first-order kinetic model (15.07 mg g(-1)) at pH 6.4, which corresponded to approximately 25\% of ASA desorption capacity. Sips isotherm model was best fitted to the equilibrium data of adsorption (50.400 mg g(-1)) at pH 2.0 and desorption (85.213 mg g(-1)) at pH(PZC) 6.4. The negative Delta H degrees showed that adsorption ( - 23.45 kJ mol(-1)) and desorption ( - 5 x 10(5)kJ mol(-1)) were exothermic processes. In addition, the regeneration capability, evaluated through the cycles of reuse, indicated increase of the adsorption and desorption capacities of 53.36\% and 32.71\%, respectively.
The 2nd generation plants producing ethanol from lignocelluloses demand risky and high investment costs. This paper presents the energy- and economical evaluations for integrating lignocellulose in current 1st generation dry mill ethanol processes, using filamentous fungi. Dry mills use grains and have mills, liquefactions, saccharifications, fermentation, and distillation to produce ethanol, while their stillage passes centrifugation, and evaporation to recycle the water and dry the cake and evaporated syrup into animal feed. In this work, a bioreactor was considered to cultivate fungi on the stillage either before or after the centrifugation step together with pretreated lignocellulosic wheat bran. The results showed that the integrated 1st and 2nd generation ethanol process requires a capital investment of 77 million USD, which could yield NPV of 162 million USD after 20 years. Compared to the fungal cultivation on thin stillage modified 1st generation process, the integrated process resulted in 53 million USD higher NPV. The energy analysis showed that the thin stillage modified 1st generation process could reduce the overall energy consumption by 2.5\% and increase the ethanol production by 4\%. Such modifications in the 1st generation processes and integration concepts could be interesting for the ethanol industries, as integrating lignocelluloses to their existing setup requires less capital investment.
Pollutants in water or wastewater raise grave public health problems. This review provides a concise summary of the potential applications of activated carbon derived from various sources. Here is an overview of the activated carbon properties and materials used to produce activated carbon. It also explores different techniques for creating active carbon for improved performance in specific applications, particularly low-cost adsorbents for heavy metal and synthetic dye removal.
Miscanthus x giganteus samples were characterized for composition and treated with hot compressed water (hydrothermal or autohydrolysis treatments) at temperatures in the range of 190-240 degrees C. The liquid phases from treatments were analyzed to assess the breakdown of susceptible polysaccharides into a scope of soluble intermediates and reaction products. The experimental concentration profiles determined for the target compounds (monosaccharides, higher saccharides, acetic acid and sugar-decomposition products) were interpreted using a pseudohomogeneous kinetic mechanism involving 27 reactions, which were governed by kinetic coefficients showing an Arrhenius-type temperature dependence. The corresponding activation energies were calculated and compared with data from the literature. The kinetic equations allowed a quantitative assessment of the experimental results, providing key information for process simulation and evaluation.
In recent years, global warming has become an important topic of public concern. As one of the most promising carbon capture technologies, solid amine adsorbents have received a lot of attention because of their high adsorption capacity, excellent selectivity, and low energy cost, which is committed to sustainable development. The preparation methods and support materials can influence the thermal stability and adsorption capacity of solid amine adsorbents. As a supporting material, it needs to meet the requirements of high pore volume and abundant hydroxyl groups. Industrial and biomass waste are expected to be a novel and cheap raw material source, contributing both carbon dioxide capture and waste recycling. The applied range of solid amine adsor-bents has been widened from flue gas to biogas and ambient air, which require different research focuses, including strengthening the selectivity of CO2 to CH4 or separating CO2 under the condition of the dilute con-centration. Several kinetic or isotherm models have been adopted to describe the adsorption process of solid amine adsorbents, which select the pseudo-first order model, pseudo-second order model, and Langmuir isotherm model most commonly. Besides searching for novel materials from solid waste and widening the applicable gases, developing the dynamic adsorption and three-dimensional models can also be a promising direction to accelerate the development of this technology. The review has combed through the recent devel-opment and covered the shortages of previous review papers, expected to promote the industrial application of solid amine adsorbents.
Utilization of microbial enzymes has been widely reported for centuries, but the commercial use of enzymes has been recently adopted. Particularly, cellulases have been utilized in various commercial sectors including agriculture, brewing, laundry, pulp and paper and textile industry. Cellulases of microbial origin have shown their potential application in various commercial sectors including textile, pulp and paper, laundry, brewing, agriculture and biofuel. Cellulases have diversified applications in the food industry, food service, food supply and its preservation. Indeed, cellulases can tenderize fruits, clarify the fruit juices, reduce roughage in dough, hydrolyze the roasted coffee, extract tea polyphenols and essential oils from olives and can increase aroma and taste in food items. However, their role in food industries has by and large remained neglected. The use of immobilized cellulases has further expanded their application in fruit and vegetable processing as it potentiates the catalytic power and reduces the cost of process. Technological and scientific developments will further expand their potential usage in the food industry.
Facing the double challenges of energy shortage and environmental pollution, development and utilization of biomass energy is of great urgency. In this review paper, the current situation and types of biomass energy are reviewed and discussed based on the world energy crisis and its environmental problems. As a typical renewable green liquid energy, bio-ethanol, made from plants with rich reserves, could be applied to the field of traffic transportation. Due to the complex structure, variety, and stable nature of plant biomass, cost-effective pretreatment technology has become an urgent demand in the bio-energy field of current world. At present, various pretreatment methods for enzymatic saccharification of plant biomass have different defects. Therefore, the research on pretreatment technology needs to comprehensively consider the heterogeneity of chemical composition and structural characteristics of raw material and the pertinence of pretreatment methods.
In recent years, we have witnessed an increasing interest in the application of mechanochemical methods for processing materials in biomass refining techniques. Grinding and mechanical pretreatment are very popular methods utilized to enhance the reactivity of polymers and plant raw materials; however, the choice of devices and their modes of action is often performed through trial and error. An inadequate choice of equipment often results in inefficient grinding, low reactivity of the product, excess energy expenditure, and significant wear of the equipment. In the present review, modern equipment employing various types of mechanical impacts, which show the highest promise for mechanochemical pretreatment of plant raw materials, is examined and compared-disc mills, attritors and bead mills, ball mills, planetary mills, vibration and vibrocentrifugal mills, roller and centrifugal roller mills, extruders, hammer mills, knife mills, pin mills, disintegrators, and jet mills. The properly chosen type of mechanochemical activation (and equipment) allows an energetically and economically sound enhancement of the reactivity of solid-phase polymers by increasing the effective surface area accessible to reagents, reducing the amount of crystalline regions and the diffusion coefficient, disordering the supramolecular structure of the material, and mechanochemically reacting with the target substances.
Bio-refinery approach using agricultural and industrial waste material as feedstock is becoming a preferred area of interest in biotechnology in the current decades. The reasons for this trend are mainly because of the declining petroleum resources, greenhouse gas emission risks and fluctuating market price of crude oil. Most chemicals synthesized petro chemically, can be produced using microbial biocatalysts. 2,3-Butanediol (BDO) is such an important platform bulk chemical with numerous industrial applications including as a fuel additive. Although microbial production of BDO is well studied, strategies that could successfully upgrade the current lab-scale researches to an industrial level have to be developed. This review presents an overview of the recent trends and developments in the microbial production of BDO from different lignocellulose biomass.
Lignocellulosic biomass is the most abundant and sustainable feedstock available globally. As a source of the polysaccharides, cellulose and hemicellulose, it can be converted into biofuels and other platform chemicals. This article highlights some important aspects that needs to be focused upon for the commercial development of lignocellulosic biorefineries. Although, lignocellulosic biomass offers clear value in terms of its green advantages and sustainability, there has been very low commercial success at industrial production levels. This can be attributed to a few key factors such as an irregular biomass supply chain, inefficient or complex pre-treatment and saccharification technologies, and scale up challenges leading to high capital and operating expenditures. Moreover, techno-economic studies performed on lignocellulosic biorefineries have revealed that process complexity is the most detrimental factor prohibiting scale-up. Although there have been several research efforts funded both by the public and private sectors, biomass valorization into biofuels and chemicals remains a technical and economical challenge. This review examines the global drivers towards the advancements of lignocellulosic biorefineries, technical and operational challenges for industrialization and future directions towards overcoming them.
Novel composite hydrogels based on pineapple peel cellulose and sepia ink were synthesized by homogeneous acetylation of cellulose in ionic liquid 1-butyl-3-methylimidazolium chloride. The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, thermogravimetry and differential scanning calorimetry. The effects of acetylation time, acetylation temperature, molar ratio of acetic anhydride/anhydroglucose unit and the additive amount of sepia ink on methylene blue adsorption capacity of the hydrogels embedded with sepia ink were also investigated. Methylene blue adsorption of the hydrogels followed pseudo-second-order kinetic model and sepia ink improved adsorption capacity significantly. The adsorption capacity at equilibrium was increased from 53.72 to 138.25 mg/g when the additive amount of sepia ink of the hydrogels was 10\%. (C) 2016 Elsevier Ltd. All rights reserved.
Escalating global population and expanding industrialisation have significantly contributed to an increased demand for plastics. Methods for plastic waste disposal predominantly involve landfilling, which consumes space and pollutes soil and water bodies, posing a substantial threat to the environment and public health. The critical challenge herein lies in efficiently managing the abundant biomass and plastics waste. Here we review gasification and pyrolysis, two prominent waste treatment processes. Co-pyrolysis of plastics and biomass exhibits a synergistic effect, significantly enhancing the yield and quality of bio-oil, biochar, and syngas. Integration of gasification and pyrolysis reduces activation energy, increases hydrogen production during co-gasification, and improves bio-oil calorific value. The gasification of polyethylene terephthalate with air in the presence of activated carbon limits tar formation with enhanced syngas production. Steam gasification enhances hydrogen generation by up to 40.0\% compared to air gasification. Selective catalysts in the integrated pyrolysis-gasification process of biomass and plastics mixtures demonstrate optimisation of the production of high-purity carbon nanotubes and bio-oil. Application of innovative approaches such as microwaves, steam purging, and catalysts like zeolite or composite catalysts enhance heat transfer mechanism, tar cracking, and devolatilisation.
The increasing global population will require sustainable means to sustain life and growth. The continuous depletion and increasing wastage of the energy resources will pose a challenge for the survival of the increasing population in the coming years. The bioconversion of waste generated at different stages of the food value chain to ethanol can provide a sustainable solution to the depleting energy resources and a sustainable way to address the growing food waste issue globally. The high carbohydrate and nitrogen content in the food waste can make it an ideal alternative substrate for developing a decentralized bioprocess. Optimizing the process can address the bottleneck issues viz. substrate collection and transport, pretreatment, fermentative organism, and product separation, which is required to make the process economic. The current review focuses on the opportunities and challenges for using the food loss and waste at different stages of the food value chain, its pretreatment, the fermentation process to produce bioethanol, and potential ways to improve the process economics. The impact of substrate, fermentative organisms' process development, downstream processing, and by-product stream to make the bioethanol production from the waste in the food value chain a commercial success are also discussed.
Ferulic acid and its hydroxycinnamate derivatives represent one of the most abundant forms of low molecular weight phenolic compounds in plant biomass. Feruloyl esterases are part of a microorganism's plant cell wall-degrading enzymatic arsenal responsible for cleaving insoluble wall-bound hydroxycinnamates and soluble cytosolic conjugates. Stimulated by industrial requirements, accelerating scientific discoveries and knowledge transfer, continuous improvement efforts have been made to identify, create and repurposed biocatalysts dedicated to plant biomass conversion and biosynthesis of high-added value molecules. Here we review the basic knowledge and recent advances in biotechnological characteristics and the gene content encoding for feruloyl esterases. Information about several enzymes is systematically organized according to their function, biochemical properties, substrate specificity, and biotechnological applications. This review contributes to further structural, functional, and biotechnological R\&D both for obtaining hydroxycinnamates from agricultural by-products as well as for lignocellulose biomass treatments aiming for production of bioethanol and other derivatives of industrial interest.
Cellulose is the most abundant natural biopolymer that can be extracted directly from plants using various treatments (alkalis, acids, ultrasonic or enzymatic treatments) or produced by microbial fermentation. It is biodegradable, biocompatible, noncytotoxic, nongenotoxic, and easily amendable, making it the most desirable material for use in the biomedical and pharmaceutical industries. The thermal, surface, and mechanical properties can be improved by using surface modification or blending with other natural polymers like alginate, polylactic acid, gelatin, etc., or using metal-based nanoparticles. Such nanocomposites, cellulose graft copolymers, and nanocrystals have been widely explored for applications in food, textile, wastewater, biomedical and pharmaceutical industries. Cellulose-derived materials have shown tremendous potential to be used as the backbone for developing wound dressings, face masks, fabrication of hydrogels, scaffolds for tissue engineering, biosensors, blood vessels, biomedicines, and drug delivery systems. The current review provides insights into cellulose production from different resources and its modification to produce high-value-added materials for biomedical applications.
Hydroxyapatite (HA), an inorganic compound, plays an essential role in the proliferation and differentiation of bone cells. Using cellulose nanocrystals (CNCs) as green dispersants to improve homogenization of HA is promising in the fabrication of nanocomposite scaffolds with biocompatibility for bone tissue engineering. The HA/CNC (HC) nanoparticle suspension was incorporated in polyvinyl alcohol (PVA)based scaffold to investigate the physical and chemical properties. The PVA/HC composites demonstrated high porous structure and swelling ability for cell attachment and a 3-fold improvement in compressive modulus compared with free HC scaffold. Moreover, the presence of HC nanoparticles has promoted the proliferation and mineralization of pre-osteoblast. Our findings could provide an effective strategy by using bio-dispersants to incorporate mineral elements into synthetic polymers for the fabrication of functional tissue engineering scaffolds. (c) 2021 Elsevier Inc. All rights reserved.
Cr(VI) is considered to be the most hazardous and toxic oxidation state of chromium and hence the development of effective removal technologies, able to provide water with Cr(VI) below the drinking water limits (US EPA 100 mu g/L, European Commission 50 mu g/L, which will be reduced to 25 by 2036) is a very important issue in water treatment. This study aimed at examining the performance of activated carbon produced from coconut shells, modified by lanthanum chloride, for Cr(VI) removal from waters. The structure of the formed material (COC-AC-La) was characterized by the application of BET, FTIR and SEM techniques. The effect of the adsorbent's dosage, pH value, contact time, initial Cr(VI) concentration and water matrix was examined with respect to Cr(VI) removal. The results indicated that the maximum Cr(VI) removal was observed at pH 5; 4 h contact time and 0.2 g/L of adsorbent's dosage was adequate to reduce Cr(VI) from 100 mu g/L to below 25 mu g/L. Freundlich isotherm and pseudo-second order kinetic models fitted the experimental data sufficiently. The maximum adsorption capacity achieved was 6.3 mu g/g at pH 5. At this pH value, the removal percentage of Cr(VI) reached 95\% for an initial Cr(VI) concertation of 30 mu g/L. At pH 7 the corresponding efficiency was roughly 60\%, resulting in residual Cr(VI) concentrations below the anticipated drinking water limit of 25 mu g/L of total chromium, when the initial Cr(VI) concentration was 50 mu g/L. Consecutive adsorption and regeneration studies were conducted using 0.01 M of NaOH as an eluent to evaluate the reusability of the adsorbents, Results showed 20\% decrease of adsorption capacity after 5 regeneration cycles of operation.
Napier grass, Pennisetum purpureum cv. Pakchong 1, was pretreated in an ionic liquid mixture through microwave irradiation. To improve the fermentable sugar yield, an acid catalyzed aqueous ionic liquid pretreatment was applied to maximize the total sugar conversion of pretreated Napier grass. Additionally, to optimize the fermentable sugar yield, experiments were carried out employing response surface methodology (RSM). The study showed that a maximum fermentable sugar concentration of 15.72g/L could be predicted from the model when Napier grass was pretreated by 1-ethyl-3-methylimidazolium acetate ({[
Hemicellulose was extracted by alkali treatment of de-pectinated cell wall material of Santalum album L. (sandalwood) suspension culture cells. The physicochemical properties and prebiotic activities of a purified major fraction of Hemicellulose-B, termed as HB-I, were investigated. GC analysis of hydrolyzed and derivatized HB-I showed the presence of arabinose (-64 \%), galactose (-16 \%) and glucose (-16 \%) as major monosaccharide units along with minor amount of rhamnose. Methylation and NMR studies on the purified polysaccharide revealed the presence of 6-\& beta;-D-Glcp, \& beta;-D-Galp, 3,5-\& alpha;-L-Araf, \& alpha;-L-Araf, 5-\& alpha;-L-Araf, 2,3-\& alpha;-L-Araf and, \& alpha;-L-Rhap residues, from which a proposed structure of repeating units was established. The growth of probiotic Lactobacillus spp. strains L. acidophilus, L. casei, L. plantarum and L. rhamnosus was promoted while that of Escherichia coli was suppressed significantly in presence of HB-I. Our results highlight valorization of sandalwood biomass and explore the role of mixed \& alpha;, \& beta;-linked heteroglycan as a potential prebiotic molecule thus indicating the possibility of development of low-cost bioprocesses for production of functional food ingredients.
Global transition towards a bio-based economy to reduce the carbon footprints as an alternative to petroleum based has led to the production of new cellulosic fibre-based eco-sustainable products in the construction and building industry. The present review gives an insight into how bio-based (fibre) is used as a reinforcement in polymer matrix composites. Specifics of the fibres in varied forms and their effect on the tensile characteristics of the resulting epoxy composites are reviewed. Studies reported to date have mostly focussed on improving the strength in the context of mechanical behaviour of the composites for varied structural applications. However, the scientific knowledge relating to modulus, its reinforcing capabilities are very limited in the literature. Detailed studies on the effect of dense regions with high moduli, less dense with insignificant moduli, point-topoint variation in the matrix are needed. This review proffers detailed explanations of the chemical treatments, hybridization, processing methods used from the last 22 years (2000-2022) in processing natural fibre composites (NFC) for value-added products. Future perspectives and functionalization of intelligence in biocomposites are also discussed.
The use of nanocrystalline cellulose (NCC) as a renewable and green biomaterial in diverse value-added applications has roused substantial interest. Sourcing NCCs from the abundantly available non-woody biomass becomes attractive due to its high cellulose content and low cost. Acid hydrolysis using mineral acids has been widely explored as a facile, low-cost, and efficient way of isolating NCCs. Still, the technical aspect of the extraction procedure is lacking. This review gathers the available knowledge on the NCC extraction using hydrolysis with mineral acids from non-woody biomass and provides a critical overview of the extraction parameters to be considered from the feedstocks and related pretreatment to the final hydrolysis procedure. To fulfill an operationally feasible production of NCCs, this review shares considerations and challenges on the biomass characteristics and pretreatment as well as hydrolysis parameters for optimizing NCC production and tailoring its application.
With the urgent need for the development of sustainable materials and a circular economy, a surge of research regarding biobased materials and associated processing methods has resulted in many experimental biobased foams. Although several biobased foams are already shown to have thermal and mechanical properties competitive with expanded polystyrene, there remains a fundamental knowledge gap leading to limited understanding of the principles that determine performance. This review outlines the progress in this burgeoning field, introducing materials selection and processing, comparing performance, examining efforts in modelling physical properties, and discusses challenges in applying models to real biobased systems. The focus is on low thermal conductivity, which is a critical property for temperature-controlled applications such as packaging for refrigerated/frozen foods, medications, and vaccines as well as building materials. Currently, the trend in the field is moving towards fully biobased and compostable foams, though partially biobased polyurethane foams remain the most consistent performers. To illustrate the foam structure-property relationship, thermal conductivity, cell size, and density data were compiled. Given the complexity of biobased foams, heat transfer models aid in identifying crucial variables. However, data relevant to the insulation capability of biobased foams is not fully reported in many references. To address this issue, we employed a dimensional analysis to fill the gaps, revealing a power law correlation between thermal conductivity and relative density. Our approach is not intended as a robust prediction technique, but rather a simple demonstration of how biobased foams data could be utilized to predict the most promising materials and methods.
Hydrodeoxygenation (HDO) of biomass waste streams constitutes a broad class of catalytic processes crucial to the sustainable manufacture of advanced biofuels. In this context, metal phosphides have received increasing attention as catalysts for HDO of vegetable oil, animal fats, bioderived phenolic streams (e.g., lignins, their depolymerization products, and pyrolysis oil). Metal phosphides present highly tunable surface chemistry accessible via uncomplicated synthetic protocols based on low-cost precursors. Herein, a critical analysis of the sustainable manufacture of advanced biofuels is provided. Emphasis is placed on nickel phosphides as catalysts with unique properties for the HDO of bioderived phenolic. The task-specific design of nickel phosphides is centered on optimizing catalyst activity, product distribution, product selectivity (aromatic vs. aliphatic hydrocarbons). In the manufacture of advanced biofuels, catalyst deactivation constitutes a primary challenge. We briefly discuss mechanisms underlining catalyst deactivation and protective effects of surface modification on the nickel phosphide stability.
Background: Pickering emulsions stabilized by solid particles have captured a growing interest recently due to their outstanding stability. Among various solid stabilizers, cellulose nanocrystals (CNCs) mainly from agricultural and forestry wastes have emerged as promising materials in Pickering emulsions application due to their favorable properties such as nanostructure, high aspect ratio, biocompatibility, amphiphilicity, low toxicity, and renewability. Scope and approach: In this review, the source and extraction methods of CNCs are summarized briefly. Then, the recent advances in CNCs stabilized Pickering emulsions are highlighted, including the factors affecting the emulsification performance of CNCs itself and the synergistic effect induced by other substances. Furthermore, the food-related research, safety issue and the promising research trends of CNCs stabilized Pickering emulsions are also outlined. Key findings and conclusions: The properties of CNCs mainly depend on the cellulose sources and extraction processes. The morphology, surface charge, wettability and crystalline allomorph of CNCs can influence emulsifying ability as Pickering stabilizers. The synergistic effect induced by other substances (i.e. polysaccharide, protein, polyphenol, lignin, surfactant, and inorganic particle) increases potential of CNCs in Pickering emulsions application. The food-related research of CNCs stabilized Pickering emulsions currently focuses on delivering bioactive compounds, improving stability and controlling lipid digestion. Future studies could devote more efforts to effective and green extraction of CNCs, revealing stabilization mechanism in a multicomponent system and developing functional applications of CNCs-based Pickering emulsions. In addition, the safety assessment involving CNCs and their stabilized emulsions deserves more attention for food-related applications.
Buriti (Mauritia flexuosa) is a robust palm tree, abundant in the northeast of Brazil. Buriti fibers are rich in cellulose and have potential applications in polymer reinforcement. In this work, buriti fibers were used: as received, mercerized and in a silanized form They were combined with cardanol-formaldehyde thermoset resin and hot-pressed to form composites Scanning electron micrograph showed that the mercerization process induced a roughness onto the fiber surface. Dynamic mechanical analyses showed that increasing the fiber content provides an improvement in the rigidity of the composites The mercerization treatment showed the best results for fiber/matrix adhesion (C) 2010 Elsevier Ltd All rights reserved.
As one main component of lignocellulosic biomass, hemicellulose is a promising alternative for the replacement of limited fossil resources to produce furfural, thus preserving a high atom efficiency. However, the complex structure of hemicellulose and the interaction between the other two components in lignocellulosic biomass (cellulose and lignin) make the effective utilization of naturally formed structure of hemicellulose challenging. This review presents an overview of the production of furfural directly from hemicellulose in lignocellulosic biomass with special emphasis on achieving the effective utilization of hemicellulose, which includes the selective dissolution of hemicellulose from lignocellulosic biomass and the selective formation of furfural from hemicellulose derivatives. Whereas the cellulose and lignin structures are retained, which can be utilized separately. Solvents and catalysts are considered as two main factors in this valorization process of hemicellulose.
Cellulose nanofibrils (CNF) are manufactured nanofibres that hold impressive expectations in forest, food, pharmaceutical, and biomedical industries. CNF production and applications are leading to an increased human exposure and thereby it is of utmost importance to assess its safety to health. In this study, we screened the cytotoxic, immunotoxic and genotoxic effects of a CNF produced by TEMPO-mediated oxidation of an industrial bleached Eucalyptus globulus kraft pulp on a co-culture of lung epithelial alveolar (A549) cells and monocyte-derived macrophages (THP-1 cells). The results indicated that low CNF concentrations can stimulate A549 cells proliferation, whereas higher concentrations are moderately toxic. Moreover, no proinflammatory cytokine IL-1 beta was detected in the co-culture medium suggesting no immunotoxicity. Although CNF treatment did not induce sizable levels of DNA damage in A549 cells, it leaded to micronuclei formation at 1.5 and 3 mu g/cm(2). These findings suggest that this type of CNF is genotoxic through aneugenic or clastogenic mechanisms. Noteworthy, cell overgrowth and genotoxicity, which are events relevant for cell malignant transformation, were observed at low CNF concentration levels, which are more realistic and relevant for human exposure, e.g., in occupational settings.
Recently, nanocellulose and its applications gain high attraction in both research and industrial areas due to its attractive properties such as excellent mechanical properties, high surface area, rich hydroxyl groups for modification, and natural properties with 100\% environmental friendliness. In this review, the background of nanocellulose originated from lignocellulosic biomass and the typical extraction meth-ods and general applications are summarized, in which the nanocellulose extraction methods related to ball milling are mainly introduced. Also, an outlook on its future is given. It is expected to provide guid-ance on the effective extraction of nanocellulose from biomass and its most possible applications in the future. (c) 2018 The Authors. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Recycling of wastes in building materials is gaining a lot of attention worldwide. This not only conserves natural resources but also enhances the properties of existing building materials leading to economical and environment friendly construction. The main aim of this study was to explore the efficiency of waste marble powder (WMP) in controlling alkali silica reactivity (ASR) of concrete. For this purpose, WMP was obtained from a marble industry. To initiate the ASR phenomena, reactive aggregate was used in the study. Mortar bar specimens prepared with WMP as cement replacement material at 10\%, 20\%, 30\% and 40\% replacement levels (by cement weight) were evaluated in the standard ASTM C1260 test method. Compressive strength and thermal analysis tests were performed to investigate the effect of WMP on strength development of concrete. Results of compressive strength and thermal analysis showed improved strength after 10\% of cement replacement with WMP. Moreover, 28\% and 50\% reduction in mortar bar expansion was observed after replacing 10\% and 40\% of cement with WMP, respectively. Scanning electron microscopic images also showed no signs of ASR cracking for mortar bars incorporating WMP. However, presence of cracks due to ASR was observed in control specimens. Furthermore, energy disperse X-ray spectroscopy (EDS) showed that amount of alkalies reduced after replacing cement with WMP, leading to overcome ASR expansion. Therefore, based on the results WMP can be effectively used to control ASR expansion leading to durable, sustainable and economical construction. (C) 2017 Elsevier Ltd. All rights reserved.
Hemicelluloses are abundant natural polysaccharides with huge availability and potential for biomaterials due to their biocompatibility and biodegradability. But their utilization in packaging is greatly limited by their intractability (hygroscopic and poor mechanical properties). In this work, the quaternized hemicelluloses (QH) were successfully prepared to increase the value of hemicelluloses. The objective of this work was the intercalation of different ratios of cationic biopolymer chitosan (CS) and QH in montmorillonite (MMT), providing compact and robust nanocomposite films with nacre like structure and multifunctional characteristics. This study revealed some details in the relationships between structure (multilayered structure) and properties (tensile strength and thermal property). It was also found that the tensile strengths of films QH-MMT-CS (F-0.05 and F-0.08) were 52.7 and 57.8 MPa, respectively, which suggested that the addition of CS was supposed to contribute to mechanical properties due to the strong electrostatic interactions and the enhanced hydrogen bonding. The thermal stability of nanocomposite films, the oxygen permeability, and water vapor permeability had been improved due to the small amount of CS. These observations create an important foundation in the experimental design of the high-performance nanocomposite materials.
Brazilian soil scientists have increased the use of the term ``soil quality{''
Enzymatic hydrolysis of biomass to produce sugars that can be converted to fuels and other valuable chemicals, is viewed as the prime technology for utilization of this renewable resource. To accelerate technology development, models are needed that are able to accurately predict the hydrolysis rate so that reactors can be tailored to the multitude of processing conditions and substrates that can be used. Of particular interest is the ability to predict the long time conversion in the hydrolysis reaction which dictates the maximum possible sugar concentration. It is our aim in this article to develop a simple model which is able to predict the long-term conversion of cellulose to soluble sugars. Drawing on the analogy from the theory of reactions in continuous mixtures, it is shown that analysis of the long time kinetics of hydrolysis by examining the behavior of the ``lump{''
The valorization of food waste is the sustainable way how to handle resources wisely. Spent coffee grounds (SCGs) are waste products of the instant coffee production and coffee brewing. The potential of Halomonas halophila to produce polyhydroxyalkanoates (PHA) from fermentable sugars derived from SCGs has been studied. This organism was able to process SCG hydrolysates as a carbon source for its growth. Diluted acid hydrolysis (4.0 vol.\% sulfuric acid, 120 min, 100 degrees C) has been employed, and three different SCG hydrolysates from non-modified SCGs, defatted SCGs and defatted SCGs with the eliminated phenolics have been prepared. However, in shake flask fermentation cultures, the growth of H. halophila was entirely inhibited on all the hydrolysates. Therefore, the hydrolysates have been detoxified using sorbent based on styrene-divinylbenzene based resins. When H. halophila was grown on detoxified hydrolysates, poly(3-hydroxybutyrate) (P3HB) was accumulated during 72 h. The biopolymer was characterized by gas chromatography, and size exclusion chromatography coupled with multiangle light scattering and differential refractometry. PHB titers reached 0.95 g/L with PHB content in bacteria cell dry mass 27\% (wt/wt), the molecular weight of the produced polymer was about 440-825 kDa. This study demonstrates that at least the detoxification of SCG hydrolysates with sorbent was necessary to promote the fermentation of H. halophila. Moreover, the extraction of coffee oil and phenolics from SCG as a detoxification pretreatment step contributes to the increase of economic and environmental values of spent coffee grounds in the case of the cascading utilization and resource recovery.
The greener chemical and enzymatic pretreatments for lignocellulosic biomasses are portraying a crucial role owing to their recalcitrant nature. Traditional pretreatments lead to partial degradation of lignin and hemicellulose moieties from the pretreated biomass. But it still restricts the enzyme accessibility for the digestibility towards the celluloses and the interaction of lignin-enzymes, nonproductively. Moreover, incursion of certain special chemical treatments and other lignin sulfonation techniques to the enzymatic pretreatment (hybrid enzymatic pretreatment) enhances the lignin structural modification, solubilization of the hemicelluloses and both saccharification and fermentation processes (SAF). This article concentrates on recent developments in various chemical and hybrid enzymatic pretreatments on biomass materials with their mode of activities. Furthermore, the issues on strategies of the existing pretreatments towards their industrial applications are highlighted, which could lead to innovative ideas to overcome the challenges and give guideline for the researchers towards the lignocellulosic biorefineries.
Valorizing constructed wetlands vegetation into biofuels can be a way to contribute to mitigating the increasing energy demand, avoiding the use of arable land, freshwater, and fertilizers consumption, while simultaneously treating wastewater with eco-friendly technology. This work shortly overviews the main genera of wetland plants and the main routes of vegetal biomass conversion into biofuels including biochemical and thermochemical processes, and through a cross-search, in the Scopus database, the research intensity in bioenergy application for each genus was assessed. A total of 283 genera of wetland plants were identified and classified into five groups, from very common to very rare genera. The very common group includes 10 genera and contributes to 62\% of the literature hits, while the 147 genera classified as very rare contribute to only 3\% of the hits. Concerning the bioenergy applications, four genera stand out from the remaining. The plants of the genus Sorghum are the most referred to in bioenergy applications, followed by the genera Brassica, Miscanthus, and Saccharum. Miscanthus is a less common wetland plant, while the other genera are rarely applied in constructed wetlands. The relevance of bioenergy routes depends on the plants' group. For common wetland plants, the most relevant applications are biogas production, followed by bio-ethanol production, and pyrolysis processing. As a recommendation for future research works the genera with high energy potential should be evaluated as wetland vegetation, and it is recommended that the goal to recover wetland vegetation for bioenergy applications be viewed as an integral step of the design and implementation of constructed wetlands facilities.
The sustainable use of plant biomass (PB) to produce new valuable compounds helps alleviate the world's excessive reliance on fossil fuels. Among the different processes available, pyrolysis has drawn significant attention for its efficiency in converting PB (including lignin, hemicellulose, and cellulose) into solid, liquid, and gas products by thermal degradation. Moreover, the participation of ionic liquids (ILs) in the pyrolysis process can further facilitate this process, improve the quality of pyrolysis products, and enhance the operational parameters. This review article presents an in-depth examination of how ILs enhance the pyrolysis of lignin, cellulose, and lignocellulose toward sustainability and circular economy (CE). The structural chemistry of the components of PB, namely cellulose, lignin, and hemicellulose, is first discussed. Furthermore, the role of ILs in the pyrolysis of cellulose, lignin, and lignocellulose is thoroughly investigated. These roles include pre-treating agent before pyrolysis, catalyst after or during pyrolysis, template during pyrolysis, and extractant after pyrolysis. In the following, the sustainability of PB pyrolysis with the participation of ILs is examined from three aspects: environmental, social, and economical. Finally, the PB pyrolysis was investigated from the CE aspect. There is no doubt that the participation of ILs in the pyrolysis process positively affects the operating conditions and product quality, so the whole process is only one step away from complete sustainability.This article is categorized under:Sustainable Development > Sustainable Development GoalsSustainable Energy > BioenergyClimate and Environment > Circular Economy
Burgeoning global energy demand and rapid diminution of fossil fuel reserves urged to seek for a sustainable energy source like bioethanol. Single pot bioprocessing (SPB) strategy employing in-house laccase, cellulase plus xylanase and amylase along with hexose and pentose sugar fermenting yeasts (Saccharomyces cerevisiae and Pichia stipitis) is designed in this study for ethanol production from biogenic municipal solid waste (BMSW). BMSW when subjected to simultaneous pretreatment and saccharification (SPS) resulted in 79.69\% enzymatic digestibility and fared better compared to alkali pretreated counterparts (14.03\%-51.10\%). The maximum total sugar release in case of SPS was 146.9 g/L in 24 h. The maximum ethanol concentration of 5.24\% (v/v) in 30 h was obtained from SPB of BMSW at 25\% (w/v) solid loading. SPB for ethanol production from BMSW is an interesting and effective alternative to MSW going to landfill or incineration with an added perk of waste to wealth conversion.
Purpose This paper aims to focus on studying the batch desorption of adsorbed crystal violet (CV) from date stones (Phoenix dactylifera), untreated (UDS) and treated using NaOH (TDS). Design/methodology/approach The process variables such as different desorbing agents, volume and concentration of the desorbing agent, contact time, dye concentration before adsorption and temperature affecting CV desorption from CV-loaded untreated date stones (CV@UDS) and treated adsorbent (CV@TDS) were optimized. The UDS and TDS were regenerated using 0.6 m HCl as eluent. Findings The HCl solution was an excellent eluent for the CV desorption from CV@UDS (96.45\%) and CV@TDS (98.11\%). The second-order model and the Langmuir model well exemplified experimental data with maximum desorption capacities were 63.29 mg g(-1) for the CV@UDS and 243.90 mg g(-1) for the CV@TDS. The calculated thermodynamic showed that the CV desorption was spontaneous, endothermic and physical. Good regeneration and reusability of UDS and TDS for the CV removal for four consecutive adsorption-desorption cycles. Practical implications This study provided a good example of reusing UDS and TDS with NaOH for fast removal of a toxic organic pollutant, CV from the wastewaters. Originality/value The use of UDS and TDS with NaOH for the first time for desorption study and their reusability to removing CV from their aqueous solutions.
Inhibitors generated during pretreatment of lignocellulosic biomass may affect the subsequent biochemical conversion to biofuels. In the present study, we tested 6 different reducing agents for their ability to detoxify steam-exploded birch used for ethanol production in a simultaneous saccharification and fermentation process. Cysteine, which was the most efficient detoxifying agent, increased both ethanol productivity and ethanol yield from 0.10 (non-detoxified) to 0.91 g/L/h and from 0.17 (non-detoxified) to 0.46 g/g, respectively. Gradual fed-batch feeding mode with a final total solid loading of 35\% (w/w) resulted in an ethanol titer of 53.2 within 72 h and a final ethanol concentration of 83.2 g/L after prolonged incubation. Moreover, residual waste (stillage) remaining after bioethanol production was subsequently used for biogas production to make the process more economically feasible. The methane yield from the stillage was 188.1 mL/g volatile solids (VS). The microbial community at the end of the biomethane process was characterized by 16S rRNA analysis. The phyla Firmicutes and Bacteroidetes were dominant members of the bacterial community, whereas the archaeal communities were dominated by methanogenic Euryarchaeota belonging to the families Methanobacteriaceae and Methanosaetaceae. (C) 2017 Elsevier Ltd. All rights reserved.
Hydrolysis kinetics and structure changes of wood meal were investigated at a temperature range of 170-330 degrees C. The weight of wood-meal residue began to decrease at 180 degrees C, reachng its lowest value at 319 degrees C. Chars were generated in the subcritical water treatment, resulting in an increase in the lignin weight in the wood-meal residue. Three zones were observed in the entire hydrolysis process, which can be described by Coats-Redfern models, yielding the activation energies and pre-exponential factors for the hydrolysis zones with a high correlation coefficient. The first-order kinetic model was the most effective one to express the hydrolysis kinetics of wood meal, yielding an activation energy of 98.8 kJ mol(-1) in Zone 1, 42.8 kJ mol(-1) in Zone 2, and 126.7 kJ mol(-1) in Zone 3. The crystalline structures of the wood-meal residue showed no great changes below 283 degrees C, but were completely destroyed at 319 degrees C. The hydrolysis behaviors of the cellulose and hemicellulose in the wood meal in the subcritical water treatment involves two steps, i.e., the surface hydrolysis and destruction of the hydrogen and glycosidic bonds. The optimal temperature for hydrolysis of wood meal to produce solid fuel and valuable chemicals is 283 degrees C.
The biorefinery concept, in which biomass is utilized for the production of fuels and chemicals, emerges as an eco-friendly, cost-effective, and renewable alternative to petrochemical-based production. The hydroxycinnamic acid fraction of lignocellulosic biomass represents an untapped source of aromatic molecules that can be converted to numerous high-value products with industrial applications, including in the flavor and fragrance sector and pharmaceuticals. This review describes several biochemical pathways useful in the development of a biorefinery concept based on the biocatalytic conversion of the hydroxycinnamic acids ferulic, caffeic, and p-coumaric acid into high-value molecules.
The expansion of the edible fungi industry has resulted in the production of large amounts of edible fungus residues, causing great pressure on environmental protection. Therefore, research on edible fungus residue utilization has become a controversial issue. Thus far, numerous efforts have been devoted to separate active substances from edible fungus substrates and residues for high application value utilization. Building upon this, the main methods for extracting active substances from edible mushroom residues are reviewed, and the mechanisms, influencing factors, and trade-offs of the various methods are analysed. Furthermore, the existing and possible directions of utilization of the extracted active substances are reviewed and discussed. Finally, challenges and prospects for the extraction and utilization of different substances in edible fungus residues are proposed. This review provides an effective strategy for protecting the ecological environment and promoting the sustainable development of human society.
In today's world, due to population increase, there are many alarming and potential catastrophic problems like climate change, environmental pollution and an enormous mass of wastes constantly produced by humankind to find innovative solutions for the management, recycling, and valorization of biowaste from agricultural production, food processing, and organic household residues. The search for sustainable and efficient wastewater treatment technologies has gained scientific interest recently; particular focus is on using biowaste to produce hydrochars (HCs) via the hydrothermal carbonization (HTC) process used as adsorbent materials for dye, heavy metal, and emerging pollutant removal. HTC materials derived from renewable resources are an environmentally friendly and adequate way to adsorb pollutants such as organic and inorganic molecules from wastewaters. This review focuses on the advantages of the HTC process which lead to improved properties of the materials obtained, making them highly efficient in wastewater treatment. The information presented in this paper was derived from the most recent publications in the field. Future perspectives of HC materials should consider the possibilities of scale-up, pretreatment of biowastes, and the optimal parameters of the HTC process to produce HCs applied for pollutant removal from wastewaters.
Cellulose nanomaterials (CNM) have the potential to become predominant nanoparticles utilized in materials engineering fields ranging from flexible electronic supports and tissue scaffolds to nanocomposite reinforcement materials and aerogels for oil capture. The potential of this emerging technological material is currently hindered by the inability efficiently to produce consistent cellulose nanomaterial-based products on an industrial scale. To quantify key properties of CNM (most notably surface properties, particle size and degree of crystallinity), several measurement methods and techniques have been employed by researchers. However, the currently available measurement techniques are too expensive (in terms of both time and money) to be applicable for high-throughput, full-scale industrial process monitoring. In an effort to highlight and identify the most critical measurement requirements, a workshop was conducted by National Institute of Standards and Technology in conjunction with the Technical Association of the Pulp and Paper Industry's Nanotechnology Conference in 2014. This workshop brought together key researchers and manufacturers at the forefront of CNM research and production. The goal of the workshop was to discuss the existing deficiencies in CNM metrology, as well as to inform and inspire measurement science development in the field.
With the coming of the ``green{''
Ethanol produced from renewable biomass, such as lignocellulosic feedstock, is one of the alternative energy resources that can be environmentally friendly. However, physical and chemical barriers caused by the close association of the main components of lignocellulosic biomass, as well as starch, hinder the hydrolysis of cellulose and hemicellulose in lignocellulose as well as amylase and amylopectin in starch to fermentable sugars. One of the main goals of pretreatment for enzymatic hydrolysis is to increase the enzyme accessibility for improving digestibility of cellulose and starch. Ultrasound irradiation applied to cellulosic materials and starch-based feedstock was found to enhance the efficiency of hydrolysis and subsequently increase the sugar yield. Prior research conducted on applying ultrasonic technology for cellulose and starch pretreatment has considered a variety of effects on physical and chemical characteristics, hydrolysis efficiency and ethanol yield. This paper reviews the application of ultrasound irradiation to cellulose and starch prior to and during hydrolysis in terms of sugar and ethanol yields. It also addresses characteristics such as accessibility, crystallinity, degree of polymerization, morphological structure, swelling power, particle size and viscosity as influenced by ultrasonic treatment. (C) 2014 Elsevier Ltd. All rights reserved.
Low cost biosorbents have gained considerable importance in the past decade for their removal efficiency of contaminants from wastewaters. Both removal and recycle of the phosphate anion through benign methods are relevant to sustain a steady balance. An attempt has been made to give a comprehensive insight into several physico-chemical factors leading to the adsorption process by various natural biosorbents. Few important facts regarding phosphate biosorption have emerged out as key points viz., pH < pHpzc, high uptake capacity; correlation with Langmuir isotherm model and pseudo second order kinetics; decrease of uptake capacity with longer contact time; enhancement of adsorption process in presence of counter ions, etc. Also, it was noted that the adsorbate: adsorbent ratio is crucial for the removal efficiency of the phosphate ions. A few biosorbents exhibit removal efficiency to a large extent (>95\%) although even higher adsorption capacity can be obtained by the modification of the adsorbents. Commercial biomatrices like biochars have shown wide applications for removal of phosphates. Magnetic biochars have shown special performance owing to the presence of iron and a porous nature of their structure. Desorption studies revealed that almost complete recovery of the phosphate ion is possible through simple ion exchange mechanism.
Current international interest in finding alternative sources of energy to the diminishing supplies of fossil fuels has encouraged research efforts in improving biofuel production technologies. In countries which lack sufficient food, the use of sustainable lignocellulosic feedstocks, for the production of bioethanol, is an attractive option. In the pre-treatment of lignocellulosic feedstocks for ethanol production, various chemicals and/or enzymatic processes are employed. These methods generally result in a range of fermentable sugars, which are subjected to microbial fermentation and distillation to produce bioethanol. However, these methods also produce compounds that are inhibitory to the microbial fermentation process. These compounds include products of sugar dehydration and lignin depolymerisation, such as organic acids, derivatised furaldehydes and phenolic acids. These compounds are known to have a severe negative impact on the ethanologenic microorganisms involved in the fermentation process by compromising the integrity of their cell membranes, inhibiting essential enzymes and negatively interact with their DNA/RNA. It is therefore important to understand the molecular mechanisms of these inhibitions, and the mechanisms by which these microorganisms show increased adaptation to such inhibitors. Presented here is a concise overview of the molecular adaptation mechanisms of ethanologenic bacteria in response to lignocellulose-derived inhibitory compounds. These include general stress response and tolerance mechanisms, which are typically those that maintain intracellular pH homeostasis and cell membrane integrity, activation/regulation of global stress responses and inhibitor substrate-specific degradation pathways. We anticipate that understanding these adaptation responses will be essential in the design of `intelligent' metabolic engineering strategies for the generation of hyper-tolerant fermentation bacteria strains.
The effects of surfactants addition on enzymatic hydrolysis and subsequent fermentation of steam exploded lodgepole pine (SELP) and ethanol pretreated lodgepole pine (EPLP) were investigated in this study. Supplementing Tween 80 during cellulase hydrolysis of SELP resulted in a 32\% increase in the cellulose-to-glucose yield. However, little improvement was obtained from hydrolyzing EPLP in the presence of the same amount of surfactant. The positive effect of surfactants on SELP hydrolysis led to an increase in final ethanol yield after the fermentation. It was found that the addition of surfactant led to a substantial increase in the amount of free enzymes in the 48 h hydrolysates derived from both substrates. The effect of surfactant addition on final ethanol yield of simultaneous saccharification and fermentation (SSF) was also investigated by using SELP in the presence of additional furfural and hydroxymethylfurfural (HMF). The results showed that the surfactants slightly increased the conversion rates of furfural and HMF during SSF process by Saccharomyces cerevisiae. The presence of furfural and HMF at the experimental concentrations did not affect the final ethanol concentration either. The strategy of applying surfactants in cellulase recycling to reduce enzyme cost is presented. (C) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 25: 1122-1129, 2009
Wood fractionation is key for the integral valorization of its three main components. In this sense, recovering the hemicellulosic fraction after the ionosolv treatment of lignocellulosic materials is one of the main drawbacks of this process. Thus, the incorporation of a previous autohydrolyisis step to recover the hemicellulosic sugars before the ionosolv treatment is an interesting approach. The influence of both treatments, autohydrolysis and ionosolv, on the biomass fractions recovery yields was studied by a central composite design of experiments, varying the autohydrolysis temperature in a 175-195 degrees C range and ionosolv time between 1-5 h. Lignin recovery and cellulose purity were maximized at 184 degrees C and 3.5 h of autohydrolysis temperature and ionosolv time, respectively. In addition, lignin properties were incorporated to the statistical model, revealing lignin recondensation at severe conditions and a higher influence of the ionosolv treatment on lignin characteristics. These results remarked the importance of studying the effect of both treatments in the whole fractionation process and not each process separately and enhanced the understanding of the treatments combination in a complete fractionation biorefinery approach.
Industrial paper wastes are an underestimated source of lignocellulosic materials. In this work cellulose nanostructures (CNS) were produced from this residue by acid hydrolysis and two chemical pretreatments consisting of an alkaline (CNS-I) or an acid (CNS-II) treatment. These pretreatments and the obtained CNSs were characterized using compositional analysis, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta potential, atomic force microscopy (AFM), and X-ray diffraction (XRD), Results reveal a reduction in the non-cellulosic compounds in pre-treated samples, with different levels of components removal and lower lignin values for alkali treatment. TGA reveals that CNSs present lower thermal stability than the residue. The SEM images revealed that pretreatment led to fiber breakage. The XDR diffractions show the co-existence of cellulose I and cellulose II, with different crystallinity index for CNSs. The DLS and AFM revealed that the production of spherical nanoparticles was following the dimensions of (similar to)195 for CNS-I and (similar to)350 nm for CNS-II. All the analysis allowed a more comprehensive understanding of the CNS properties and their possible applications. Finally, it is possible to conclude that the conversion of paper wastes into CNS is an excellent opportunity to recovery this residue and aggregate value to them.
Microalgal biomass is the third-generation promising feedstock for production of biofuel and other valuable goods. The raw microalgal biomass and residues have low calorific value, high moisture, and high H/C and O/C atomic ratio which not suitable to use as solid fuel and many engineering applications. Torrefaction is a promising technique to upgrade microalgal biomass closed to solid coal properties by increasing the calorific value of microalgal biochar. However, the overview of torrefaction process for microalgal biochar is lacking in the literature study. Thus, an overview of recent dry and wet torrefaction of microalgal biomass is presented in this review. Wet torrefaction is a new technology for microalgal biochar production because it has some advantages compare with other pre-treatment methods. Besides, this review aims to provide a comprehensive overview of recent research for fuel property of microalgal biochar after torrefaction process. Different torrefaction temperature, gases and holding time lead to various solid yield, energy yield and calorific value of biochar are comprehensively discussed. In addition, the used of microalgal biochar as bio-adsorbent to remove pollutants in wastewater are included as well. In short, this is a comprehensive summary of recent torrefaction technology for microalgal biochar as fuel.
In this study, a bamboo charcoal-based solid acid catalyst (BC) was generated by one-step carbonization and sulfonation at 150 degrees C for 4 h in the presence of sulfuric acid. The BC was characterized by Fourier transform infrared spectrometry, elemental analysis, X-ray powder diffraction, and Brunauer-Emmet-Teller specific surface area analysis. The BC had a specific surface area of 4.54 m2/g, pore volume of 0.0142 cm3/g, and acid density of 1.476 mmol/g. Subsequently, the catalytic activity and deactivation mechanism of the BC in the esterification of soybean saponin acid oil (SAO) and methanol were investigated. The results showed that the conversion yield of esterification reached 98.28\% under optimal reaction conditions (i.e., catalyst addition of 10 wt\%, methanol/oil molar ratio of 10:1, temperature of 65 degrees C, and time of 8 h). The conversion yield decreased as reuse batches increased, and was below 80\% after three batches. The loss of sulfonic acid groups from the BC occurred mainly in the first esterification batch, caused by residual sulfuric acid leaching and chemical derivatization of sulfonic acid groups. In the second to fourth esterification batches, chemical derivatization was the main reason for deactivation, where the generation of sulfonate esters and exchange of metal cations with hydrogen ions accounted for more than 75\% of the chemical derivatization loss. Therefore, without impurity purification of SAO, reducing the amount of sulfonate ester generated on the catalyst was found to be essential for increasing the reuse performance of the BC and reducing the cost of biodiesel production.
This study explores adsorptive removal measures to shed light on current water treatment innovations for kinetic/isotherm models and their applications to antibiotic pollutants using a broad range of biomass-based adsorbents. The structure, classifications, sources, distribution, and different techniques for the remediation of antibiotics are discussed. Unlike previous studies, a wide range of adsorbents are covered and adsorption of comprehensive classes of antibiotics onto biomass/biochar-based adsorbents are categorized as beta-lactam, fluoroquinolone, sulfonamide, tetracycline, macrolides, chloramphenicol, antiseptic additives, glycosamides, reductase inhibitors, and multiple antibiotic systems. This allows for an assessment of their performance and an understanding of current research breakthroughs in applying various adsorbent materials for antibiotic removal. Distinct from other studies in the field, the theoretical basis of different isotherm and kinetics models and the corresponding experimental insights into their applications to antibiotics are discussed extensively, thereby identifying the associated strengths, limitations, and efficacy of kinetics and isotherms for describing the performances of the adsorbents. In addition, we explore the regeneration of adsorbents and the potential applications of the adsorbents in engineering. Lastly, scholars will be able to grasp the present resources employed and the future necessities for antibiotic wastewater remediation.
Gasification is a thermochemical process to convert the biomass chemical energy into a gaseous fuel, which is a suitable renewable energy source as a substitute for fossil fuel. Research on this technology has been developed to improve its efficiency and syngas quality. Computational modeling of the gasification process is an advantageous tool for predicting a complex process reducing actual experiments. This paper aims to present an updated review of application of stoichiometric thermodynamic equilibrium model that was widely investigated on the scientific literature. Due to its limitations in being based on ideal theoretical conditions, some authors modified the model based on experimental data to obtain more accurate results. The review presented in this work comprehends explaining the method of model implementation highlighting main modifications proposed by authors. The importance of this study is that the extensive literature review of model modifications provides a better understanding of gasification modeling that may serve as a basis for future research. In this way, further works will be able to develop new approaches for this model, contributing to the scientific knowledge of the area. As result of this research it was possible to point out as main modifications the following topics: to include tar and/or char; and to force the change in the equilibrium of reactions through the application of multiplication factors to equilibrium constants. It was proved that modified models predict the gas composition much closer to the experimental value than the basic model.
A novel xylanase gene, xyn-lxy, was cloned from a metagenomic fosmid library, which was previously constructed from the rumen contents of Hu sheep and was functionally characterized in Escherichia coli. The open reading frame was composed of 1923 bp and encoded for 640 amino acids, including a catalytic domain of glycosyl hydrolase family 10 and carbohydrate-binding module 9. The gene showed 97 \% identity with uncultured bacterium Contig1552 but low similarity with xylanases from known cellulolytic-degrading microorganisms in the rumen. The recombinant XYN-LXY showed a specific activity of 664.7 U mg(-1). The optimal temperature and pH of the enzyme were 50 A degrees C and 6.0, respectively. Specifically, XYN-LXY was exclusively activated by Mn2+ among all of the cations and reducing agents tested in this study. An enzymatic hydrolysis assay revealed that XYN-LXY degraded birchwood xylan into xylooligosaccharide with a low degree of polymerization. After incubation for 4 h, the concentration of the dominant product, xylobiose, was 2.297 A +/- 0.175 mg ml(-1) (74.07 \% of total product) followed by xylose with a concentration of 0.656 A +/- 0.010 mg ml(-1) (21.14 \% of total product). The XYN-LXY exhibited deep degradation effects on the xylan substrate, which were rarely observed with endo-xylanase, making it a promising candidate for industrial application, especially in biofuel production.
Sorghum bicolor (L.) (Moench), which stands out for dry matter yield per hectare, has been considered as potential raw material for biofuels and electricity generation. It has a production cycle of six months, possibility of mechanization of cultivation and harvest and good adaptation to most regions of Brazil. Sorghum genotypes were evaluated for agronomic potential and chemical composition favorable to the production of second-generation ethanol. Three brown midrib (bmr) sorghum mutant hybrids were compared to three conventional hybrids. The bmr sorghum mutant hybrids are associated with reduced lignin content, making these genotypes more promising to the enzymatic conversion processes of the biomass. Sorghum biomass showed a high potential in terms of biomass production, with an average dry matter yield of 26.57 Mg ha(-1). Brown midrib sorghum hybrids showed significantly lower lignin contents than conventional hybrids and demonstrated the potential for cellulosic ethanol production.
Globally agricultural production system generates a huge amount of solid waste. Improper agri-waste management causes environmental pollution which resulted in economic losses and human health-related problems. Hence, there is an urgent need to design and develop eco-friendly, cost-effective, and socially acceptable agriwaste management technologies. Agri-waste has high energy conversion efficiency as compared to fossil fuelbased energy generation materials. Agri-waste can potentially be exploited for the production of secondgeneration biofuels. However, composted agri-waste can be an alternative to energy-intensive chemical fertilizers in organic production systems. Furthermore, value-added agri-waste can be a potential feedstock for livestock and industrial products. But comprehensive information concerning agri-waste management is lacking in the literature. Therefore, the present study reviewed the latest advancements in efficient agri-waste management technologies. This latest review will help the researchers and policy planners to formulate environmentally robust residue management practices for achieving a green economy in the agricultural production sector.
AGREEN polymer containing specific functional groups with the ability to absorb high dosages of contaminated dyes \& heavy metals from the waste water was achieved. The surface properties of the waste cotton tissues were improved through its surface modification by graft polymerization using gamma-radiation60Co to acquire new properties such as hydrophilic or hydrophobic character based on the chemical structure of the used monomer. The nucleophiles surface cotton fiber modification was done by introducing an anionic monomer (2-acrylamide-2methyl propane sulfonic acid, AMPS) and nano magnetite particles to easily facilitate separation of toxic substances. Factors influencing the grafting such as monomer concentration, radiation dose were studied. The structure surface properties of the grafted fabric were characterized by XRD, SEM, TGA and IR. The results obtained show high and green removal efficiency of Cd(II), Co(II) and cationic dyes (methylene blue) from waste water.
Poly(lactic acid) (PLA) is one of the most well-known biopolymers. PLA is bio-based, biocompatible, biodegradable, and easy to produce. This polymer has been used to create natural fiber reinforced composites. However, to produce high-performance and presumably biodegradable composites, the interphase between PLA and natural fibers still requires further study. As such, we aimed to produce PLA-based composites reinforced with a commercial bleached kraft eucalyptus pulp. To become a real alternative, fully biodegradable composites must have similar properties to commercial materials. The results found in this research support the competence of wood fiber reinforced PLA composites to replace other glass fiber reinforced polypropylene composites from a tensile property point of view. Furthermore, the micromechanics analysis showed that obtaining strong interphases between the PLA and the reinforcement is possible without using any coupling agent. This work shows the ability of totally bio-based composites that fulfill the principles of green chemistry to replace composites based on polyolefin and high contents of glass fiber. To the best knowledge of the authors, previous studies obtaining such properties or lower ones involved the use of reagents or the modification of the fiber surfaces.
The macromolecule sodium lignosulfonate (SL) has been investigated as dispersing agent for aqueous alumina colloids as a renewable alternative to usual petrochemical stabilizing agents. Optimization of the SL concentration necessary to stabilize the alumina suspension at different pH values was determined by viscometer. The results showed that addition of 250 ppm of the total suspension mass led to about 70\% viscosity reduction of the suspension, whereas zeta potential analysis revealed negative values for the SL suspensions throughout the pH range investigated, suggesting that the alumina particles were covered by negatively charged SL molecules. Particle size investigation informed that the average particle diameter of the SL suspensions was smaller compared to that of the pristine particles. Sedimentation time for the SL suspensions was dramatically longer than that for the pristine one. The reported data strongly corroborated that SL is a suitable renewable dispersing agent for aqueous alumina colloids. (C) 2015 Elsevier B.V. All rights reserved.
Cell immobilization has shown to be especially adequate for xylitol production. This work studies the suitability of the air lift bioreactor for xylitol production by Debaryomyces hansenii immobilized in Ca-alginate operating in fed-batch cultures to avoid substrate inhibition. The results showed that the air lift bioreactor is an adequate system since the minimum air flow required for fluidization was even lower than that leading to the microaerobic conditions that trigger xylitol accumulation by this yeast, also maintaining the integrity of the alginate beads and the viability of the immobilized cells until 3 months of reuses. Maximum productivities and yields of 0.43 g/l/h and 0.71 g/g were achieved with a xylose concentration of 60 g/l after each feeding. The xylose feeding rate, the air flow, and the biomass concentration at the beginning of the fed-batch operation have shown to be critical parameters for achieving high productivities and yields. Although a maximum xylitol production of 139 g/l was obtained, product inhibition was evidenced in batch experiments, which allowed estimating at 200 and 275 g/l the IC50 for xylitol productivity and yield, respectively. The remarkable production of glycerol in the absence of glucose was noticeable, which could not only be attributed to the osmoregulatory function of this polyol in conditions of high osmotic pressure caused by high xylitol concentrations but also to the role of the glycerol synthesis pathway in the regeneration of NAD(+) in conditions of suboptimal microaeration caused by insufficient aeration or high oxygen demand when high biomass concentrations were achieved.
Among the bioremediation processes, biostimulation is an effective methodology for the decontamination of organic waste by the addition of agents that stimulate the indigenous microbiota development. Rice hull is a biostimulating agent that promotes the aeration of edaphic systems and stimulates the aerobiotic activity of soil microorganisms. The present study aimed to evaluate the efficacy of the bioremediation and biostimulation processes in reducing the toxicity of sewage sludge (SS) and to evaluate its possible application in agriculture using cytotoxic and genotoxic assays in human hepatoma cells (HepG2). SS of domestic origin was tested as both the pure product (PSS) and mixed with soil (5) and with a stimulating agent, such as rice hull (RH), in different proportions (SS + S and SS + S + RH); we also examined different remediation periods (3 months - T1 and 6 months - T2). For the PSS sample, a significant induction of micronucleus (MN) in T2 was observed with nuclear buds in all of the periods assessed, and we observed the presence of more than one alteration per cell (MN and nuclear bud) in T1 and T2. The PSS sample caused genotoxic effects in the HepG2 cells even after being bioremediated. For the samples containing soil and/or rice hull, no toxic effects were observed in the test system used. Therefore, the addition of SS to agricultural soils should be conducted with caution, and it is important that the SS undergoes a remediation process, such as bioremediation and biostimulation treatments. (C) 2018 Elsevier Ltd. All rights reserved.
The effect of the H2SO4 concentration in the hydrolysis of sunflower-stalk waste, at 95oC and using a liquid/solid relation of 20, was studied. In a later stage, the hydrolysates were fermented at different temperatures with the aim of ethanol and xylitol production. A total conversion of the hemicellulose at the acid concentration of 0.5 mol/L was achieved; whereas an acid concentration of 2.5 mol/L was needed to reach the maximum value in the conversion of the cellulose fraction. The analysis of the hydrolysis kinetics has enabled to determine the apparent reaction order, which was 1.3. The hydrolysates from hydrolysis process with H2SO4 0.5 mol/L, once detoxified, were fermented at pH 5.5, temperatures 30, 40, and 50oC with the yeast Hansenula polymorpha (ATCC 34438), resulting in a sequential uptake of sugars. In relation to ethanol and xylitol yields, the best results were observed at 50 degrees C (YE/sO = 0.11 g/g; YXy/sO = 0.12 g/g). Instantaneous xylitol yields were higher than in ethanol, at the three temperatures essayed. Different phenolic compounds were analyzed in the hydrolysates; hydroxytyrosol was the most abundant (3.79 mg/L). The recovery of these compounds entails the elimination of inhibitors in the fermentation process and the production of high value-added antioxidant products.
In the present study, activated carbon (AC) was prepared from jackfruit leaves (JFL) using phosphoric acid as activating agent. The prepared AC was characterized by Fourier-transform infrared spectroscopy, nitrogen adsorption???desorption analyses and scanning electron microscopy. The adsorptive performance of the prepared activated was investigated by the adsorption of anionic dye methyl orange (MO) from aqueous solutions. The batch adsorption experiments were carried by varying operation parameters such as pH, adsorbent dosage, initial concentration of dye and contact time. The adsorption capacity was increased with increasing concentration of dye. The equilibrium adsorption data were well fitted to Langmuir isotherm model and maximum adsorption capacity was obtained to be 833 mg/g. The adsorption followed the pseudo-second-order kinetic model. Thermodynamic study suggested the endothermic nature of MO adsorption onto prepared activated carbon. Considering high dye adsorption capacity, AC prepared from jackfruit leaves can be used as a promising low-cost adsorbent for the removal of organic dyes from aqueous solution.
According to the 12 principles of green chemistry, surface functionalization was performed using glutaric an-hydride under solvent-free and catalyst-free conditions. FTIR spectra and DS analyses demonstrated the func-tionalization of HCl-hydrolyzed cellulose. The influence of two parameters, i.e., the glutaric anhydride concentration and the reaction time, on the functionalization of HCl-hydrolyzed cellulose was investigated. Protocol efficiency was studied by a degree of substitution (DS). It was found that higher concentrations of glutaric anhydride cause an enhancement of DS to 0.75 and 0.87 for GA3-12 and GA9-12, respectively. In addition, the longer reaction time increased zeta potential from-12.2 +/- 1.7 for G9-6 to-34.57 +/- 2.2 for GA9-12. Morphology analysis by SEM showed a decrease in fiber length for the functionalized cellulose. DSC profiles confirmed dehydration at a range of 17 to 134 degrees C. A glass transition was revealed at-30 to-20 degrees C for all studied samples. The fusion, the depolymerization of cellulose chains, the cleavage of glycosidic linkages, and the decomposition of the crystalline parts of cellulose occur at 195 to 374 degrees C. Therefore, an efficient and greener process was developed to functionalize the HCl-hydrolyzed cellulose by glutaric anhydride, a safe and non-toxic anhydride, in the absence of the solvent and catalyst.
Rapeseed and sunflower are two of the world's major oilseeds. Rapeseed and sunflower meal (RSM and SFM), the by-products of oil extraction, are produced in large quantities. They are mainly composed of proteins, lignocellulosic fibres and minerals. They were initially used as a protein complement in animal feed rations and sometimes as fertilizer or as combustible source. More recently, new alternatives to these traditional uses have been developed that draw on the structure and physicochemical properties of RSM and SFM, which are plentiful sources of nitrogen and carbon nutrients. This feature, together with their cheapness and ready availability, supports the cultivation of various microorganisms in both submerged cultures and solid-state fermentation. Recent studies have thus emphasized the potential utilisation of RSM and SFM in fermentative processes, including saccharification and production of enzymes, antibiotics, antioxidants and other bio-products, opening new challenging perspectives in white biotechnology applications.
In this research, sweet potato starch and oregano (OEO) or thyme (TEO) essential oil at two concentrations (7.5 and 10 \%) were used to produce bioactive foams by thermopressing. The foams were characterized according to microstructure, mechanical properties, antimicrobial properties, and structural properties by X-ray diffraction, scanning electron microscopy, and Fourier-transform-infrared spectroscopy (FT-IR). In all cases, essential oil addition affected the foam color, yielding reddish/yellowish foams, but not the foam thickness. FT-IR spectrum and X-ray diffraction revealed starch-lipid interactions. According to the micrographs, the lipids were localized in the first layer. Thus, formation of amylose-essential oil complexes in the foam may have prevented the essential oil from degrading under the thermoforming temperature. Essential oil addition yielded starch foams with low water solubility and mechanical resistance, especially for 10 \% OEO. Meanwhile, these foams were more effective against Salmonella (Gram-negative bacteria) and L. monocytogenes (Gram-positive bacteria). The antimicrobial activity of the foams containing essential oil makes them beneficial for application as bioactive materials. Therefore, bioactive sweet potato starch-based foams can be prepared by thermopressing and be applied as food container.
Biochar is considered to be a potential soil amendment. However, its implications for soil physical and hydraulic properties have not been widely discussed. Changes in the soil physical environment influence the numerous services that soils provide. This paper (i) reviewed the impacts of biochar on soil compaction, mechanical, structural, hydraulic, and thermal properties; (ii) discussed factors affecting biochar performance; and (iii) identified research areas. Biochar generally reduces soil bulk density by 3 to 31\%, increases porosity by 14 to 64\%, and has limited or no effects on penetration resistance. Biochar increases wet aggregate stability by 3 to 226\%, improves soil consistency, and has mixed effects on dry soil aggregate stability. It increases available water by 4 to 130\%. Saturated hydraulic conductivity decreases in coarse-textured soils, and increases in fine-textured soils following biochar application. Studies on other properties are few but suggest that biochar reduces tensile strength and particle density, alters water infiltration, moderates soil thermal properties, and has minimal effect on soil water repellency. Sandy soils appear to respond more to biochar than clayey soils. Biochar effectiveness increases as the amount of biochar applied increases. A decrease in biochar particle size can increase water retention but may reduce saturated flow. Field-scale and long-term studies assessing all soil physical properties under different scenarios of biochar management are needed. Overall, biochar generally improves the soil physical environment, but long-term field studies are lacking to conclusively ascertain the extent of biochar effects.
Lignin extraction from black liquor (BL) was investigated employing four deep eutectic solvents (DESs) and a control solvent ({[
Requirement of clean energy sources urges us to find substitutes for fossil fuels. Microorganisms provide an option to produce feedstock for biofuel production by utilizing inexpensive, renewable biomass. Rhodotorula toruloides (Rhodosporidium toruloides), a non-conventional oleaginous yeast, can accumulate intracellular lipids (single cell oil, SCO) more than 70\% of its cell dry weight. At present, the SCO-based biodiesel is not a price-competitive fuel to the petroleum diesel. Many efforts are made to cut the cost of SCO by strengthening the performance of genetically modified R. toruloides strains and by valorization of low-cost biomass, including crude glycerol, lignocellulosic hydrolysates, food and agro waste, wastewater, and volatile fatty acids. Besides, optimization of fermentation and SCO recovery processes are carefully studied as well. Recently, new R. toruloides strains are developed via metabolic engineering and synthetic biology methods to produce value-added chemicals, such as sesquiterpenes, fatty acid esters, fatty alcohols, carotenoids, and building block chemicals. This review summarizes recent advances in the main aspects of R. toruloides studies, namely, construction of strains with new traits, valorization of low-cost biomass, process detection and optimization, and product recovery. In general, R. toruloides is a promising microbial cell factory for production of biochemicals.
Hazelnut shells, a high lignin containing biomass, were subjected to individual and sequential liquid hot water (LHW), alkaline (AP) and dilute acid pretreatments (DAP). Among the single pretreatments, LHW demonstrated the highest cellulose recovery of 98.1\%, DAP resulted in the highest hemicellulose solubilization of 56.0\%, and AP of the highest lignin removal of 49.6\%. Employing two-step pretreatment on hazelnut shells, in general, demonstrated an enhanced action of the second pretreatment; therefore, the sequence of the pretreatment methods had a significant impact on both substrate characteristics and enzymatic hydrolysis efficiency of biomass. In terms of delignification, AP-LHW achieved 60.7\% lignin removal, while LHW-DAP showed the highest hemicellulose removal of 93.8\% and DAP-LHW resulted in the highest cellulose recovery of 94.0\%. Structural properties of raw and pretreated hazelnut shells were observed by FTIR. The maximum glucose recovery of 54.9\% was observed in DAP-LHW pretreated samples. For this pretreatment combination, almost 1.8 MJ total energy was required to recover 10.2 g glucose. The findings indicated that complete removal of the physical barrier of lignin and hemicellulose might not be essential; partial relocation of lignin and alteration of cellulose structure may also be efficient in increasing the sugar recovery from the lignocellulosic biomass.
Industrial company such as textile, leather, cosmetics, paper and plastic generated wastewater containing large amount of dye colour. The removal of dye materials are importance as the presence of this kind of pollutant influence the quality of water and makes it aesthetically unpleasant. As their chemical structures are complicated, it is difficult to treat dyes with municipal waste treatment operations. Even a small quantity of dye does cause high visibility and undesirability. There have been various treatment technique reviewed for the removal of dye in wastewater. However, these treatment process has made it to another expensive treatment method. This review focus on the application of adsorbent in dye removal from textile wastewater as the most economical and effective method, adsorption has become the most preferred method to remove dye. The review provides literature information about different basis materials used to produce activated carbon like agricultural waste and industrial waste as well as the operational parameters factors in term of contact time, adsorbent dosage, pH solution and initial dye concentration that will affect the process in removing textile dye. This review approach the low cost and environmental friendly adsorbent for replacing conventional activated carbon.
Corn stover, an underutilized agricultural residue, is a promising lignocellulosic feedstock for producing biofuels. To fully utilize it, pretreatment is needed. Typically, pretreatments are rapidly assessed using extracellular enzymes that release sugars from cellulose and hemicellulose. In contrast, this study uses methane-arrested anaerobic digestion (MAAD) to assess pretreatments. Although time consuming, MAAD is a more accurate assessment technique when lignocellulose is employed in the carboxylate platform, a promising approach that utilizes nearly all biomass components. Using recommended pretreatment conditions identified from a previous study, three corn stover pretreatments were compared using MAAD: (1) shock-only, (2) NaOH-only, and (3) shock + NaOH. Air-dried sewage sludge was used as nutrient source. At 100 g/L initial substrate concentration, compared to untreated corn stover, shock-only decreased conversion (amount of biomass digested) by 14\%, NaOH-only increased conversion by 82\%, and shock + NaOH increased conversion by 104\%. Using batch MAAD data, the continuum particle distribution model simulated four-stage countercurrent fermentation. At an industrial non-acid volatile solids (NAVS) concentration of 300 g/L-liq, for both NaOH-only and shock + NaOH, the model predicts total carboxylic acid concentration of about 58 g/L and conversion of about 0.85 g NAVS(digested)/g NAVS(fed) at liquid retention time of 35 days and volatile solid loading rate of 4 g/(L-liq.day). At this long solid residence time, shock is not necessary; however, with short solid residence times, shock acts synergistically to aid NaOH pretreatment. Shock treatment offers a way to reduce pretreatment costs without sacrificing pretreatment efficacy.
The adsorption of crystal violet (CV) and malachite green (MG) dyes using carbon-coated Zn-Al-layered double hydroxide (C-Zn-Al LDH) was investigated in this work. The characterisation of both Zn-Al LDH and C-Zn-Al LDH was performed using XRD, SEM, TEM, EDX, XPS, FTIR, BET and TGA. The results indicated that carbon particles were effectively coated on Zn-Al LDH surface. The average total pore volume and pore diameter of C-Zn-Al LDH were observed as 0.007cc/g and 3.115nm. The impact of parameters like initial dye concentration, pH and adsorbent dosage on the dye removal efficiency was confirmed by carrying out Box-Behnken design experiments. Langmuir isotherm was well suited for both CV and MG adsorption among other isotherm models. The adsorption capacity was maximally obtained as 129.87 and 126.58mg/g for CV and MG respectively. Pseudo-second order fits the adsorption kinetics than any other kinetic models for both the dyes. The thermodynamic study indicates that the adsorption process of CV was exothermic, whereas for MG was endothermic. Electrostatic attraction, H-bonding, n- and - interactions were mainly influenced in the adsorption process. This study concludes that C-Zn-Al LDH is an efficient adsorbent for the CV and MG dye removal from aqueous solutions.
When subjected to microwave ageing, the microwave-induced improvement in properties is more significant for sample containing higher loading fraction of cellulose nanofiller. This is due to cellulose nanofiller has greater reactivity to microwave energy through activation of dipole-dipole interaction at the polar interface. The strengthening effects on interface were observed to magnify as a function of microwave power and irradiation time. Nevertheless, the higher montmorillonite fraction tended to inhibit such improvement effect due to the occurrence of intramolecular repulsion between montmorillonite and polysaccharides with insufficient irradiation time, facilitating the water absorption and uneven stress transfer.
Using bioconversion and simultaneous value-added product generation requires purification of the gaseous and the liquid streams before, during, and after the bioconversion process. The effect of diversified process parameters on the efficiency of biohydrogen generation via biological processes is a broad object of research. Biomass-based raw materials are often applied in investigations regarding biohydrogen generation using dark fermentation and photo fermentation microorganisms. The literature lacks information regarding model mixtures of lignocellulose and starch-based biomass, while the research is carried out based on a single type of raw material. The utilization of lignocellulosic and starch biomasses as the substrates for bioconversion processes requires the decomposition of lignocellulosic polymers into hexoses and pentoses. Among the components of lignocelluloses, mainly lignin is responsible for biomass recalcitrance. The natural carbohydrate-lignin shields must be disrupted to enable lignin removal before biomass hydrolysis and fermentation. The matrix of chemical compounds resulting from this kind of pretreatment may significantly affect the efficiency of biotransformation processes. Therefore, the actual state of knowledge on the factors affecting the culture of dark fermentation and photo fermentation microorganisms and their adaptation to fermentation of hydrolysates obtained from biomass requires to be monitored and a state of the art regarding this topic shall become a contribution to the field of bioconversion processes and the management of liquid streams after fermentation. The future research direction should be recognized as striving to simplification of the procedure, applying the assumptions of the circular economy and the responsible generation of liquid and gas streams that can be used and purified without large energy expenditure. The optimization of pre-treatment steps is crucial for the latter stages of the procedure.
The finite nature of fossil fuels and the environmental impact of its use have raised interest in alternate renewable energy sources. Specifically, nonfood carbohydrates, such as lignocellulosic biomass, can be used to produce next generation biofuels, including cellulosic ethanol and other nonethanol fuels like butanol. However, currently there is no native microorganism that can ferment all lignocellulosic sugars to fuel molecules. Thus, research is focused on engineering improved microbial biocatalysts for production of liquid fuels at high productivity, titer, and yield. A clear understanding and application of the basic principles of microbial physiology and biochemistry are crucial to achieve this goal. In this review, we present and discuss the construction of microbial biocatalysts that integrate these principles with ethanol-producing Escherichia coli as an example of metabolic engineering. These principles also apply to fermentation of lignocellulosic sugars to other chemicals that are currently produced from petroleum.
Biofuels and their production is the need of the hour considering the current fuel crisis. In this regard, ways of mitigating biodiesel production costs is being actively researched upon. With the same intention, in the present work, an investigation was carried out to test the capability of utilizing the hydrolysates of de-oiled Pongamia seed cake, a byproduct of biodiesel, for microbial lipid production using Aspergillus ochraceus. This is the first time A. ochraceus is being reported to be used to evaluate its oleaginous property. Also, Pongamia seed cake is the novel source being used for microbial lipid production. The different variants of the seed cake based medium proved acid hydrolysate of de-oiled seed cake to be the effective medium for lipid production. The values recorded for maximum biomass titer, lipid titer and lipid content were 3.065 +/- 0.248 g/L, 0.849 +/- 0.056 g/L and 28.93\%, respectively, upon using acid hydrolysate of the seed cake. The fatty acid composition obtained by GC-MS analysis revealed the presence of linoleic, oleic, stearic and palmitic acids as the major fatty acid components in the lipids produced proving their similarity to the vegetable oils. The fuel properties of the lipids produced were found be in accordance with the standard specifications making them a very good source for biodiesel production. The findings from the current study reveal the effectiveness of Pongamia seed cake for microbial lipid production and simultaneous value addition to the biodiesel industry.
Biochar properties are significantly influenced and controlled by biomass feedstock type and pyrolysis operating conditions, and the development of multiple biochar properties for various applications has necessitated the need for blending different feedstocks together. Co-pyrolysis as a potential technology has been proposed to improve the overall performance of biomass pyrolysis and has proved effective in improving biochar properties. Consequently, the combination of lignocellulosic and macroalgae biomasses has been targeted for biochar production and improvement of biochar properties through co-pyrolysis. This paper therefore presents a critical review of biochar production from co-pyrolysis of lignocellulosic and macroalgae biomass (CLMB). It discusses the biomass feedstock selection, characterization, pre-processing and suitability for thermal processing; and analyzes biochar production, characterization and reactor technologies for CLMB. Furthermore, the potential and economic viability of biochar production system from CLMB are highlighted; and finally, the current state and future directions of biochar production from CLMB are extensively discussed.
Biomass is an abundant renewable energy source and a potential feedstock for producing industrial chemicals. Consequently, biomass has received growing attention as a feedstock for production of advanced materials, because of the added value of the end products and the environmental acceptance of the processes. In this respect, various routes have been used to synthesize diverse structures of biomass-based carbon materials, in particular hierarchical porous carbon materials. The structure and surface chemical composition of the porous carbon dictates its applications. In this reported work, the recent progress achieved in the synthesis of biomass-based porous carbons is reviewed to provide a systematic understanding of this research frontier and to provide a glimpse into the future prospects of biomass-based porous carbons.
In this paper, the authors propose a model for DDT biodegradation by bacteria grown in microniches created in the porous structure of green bean coffee. Five bacteria isolated from coffee beans, identified as Pseudomonas aeruginosa, P. putida, Stenotrophomonas maltophilia, Flavimonas oryzihabitans, and Morganella morganii. P. aeruginosa and F oryzihabitans, were selected for pesticide degradation. Bacteria were selected according to their ability to grow on mineral media amended with: (a) glucose (10 g 1), (b) peptone (2gl(-1)), and (c) ground coffee beans (2gl(-1)). These three media were supplemented with 50mgl(-1) of 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) and endosulfan. GC/MS analysis demonstrated that the greatest DDT removal was obtained in the medium supplemented with coffee beans, where 1,1-dichloro-2,2'-bis (4-chlorophenyl)ethylene (DDE), 1-chloro-2,2-bis (4-chlorophenyl) ethane (DDMU) and 2,2-bis (p-chlorophenyl)ethanol (DDOH) were detected. DDMU is a product of the reductive dechlorination of DDE, which in this system could be carried out under the anaerobic conditions in microniches present in the porous structure of the coffee bean. This was supported by scanning electron microscopy. Green bean coffee could be used as a nutrient source and as a support for bacterial growth in pesticide degradation. (c) 2006 Published by Elsevier Ltd.
Lignocellulosic biomass is an attractive raw material for the sustainable production of chemicals and materials using microbial cell factories. Most of the existing bioprocesses focus on second-generation ethanol production using genetically modified Saccharomyces cerevisiae, however, this microorganism is naturally unable to consume xylose. Moreover, extensive metabolic engineering has to be carried out to achieve high production levels of industrially relevant building blocks. Hence, the use of non-Saccharomyces species, or non-conventional yeasts, bearing native metabolic routes, allows conversion of a wide range of substrates into different products, and higher tolerance to inhibitors improves the efficiency of biorefineries. In this study, nine non-conventional yeast strains were selected and screened on a diluted hemicellulosic hydrolysate from Birch. Kluyveromyces marxianus CBS 6556, Scheffersomyces stipitis CBS 5773, Lipomyces starkeyi DSM 70295, and Rhodotorula toruloides CCT 7815 were selected for further characterization, where their growth and substrate consumption patterns were analyzed under industrially relevant substrate concentrations and controlled environmental conditions in bioreactors. K. marxianus CBS 6556 performed poorly under higher hydrolysate concentrations, although this yeast was determined among the fastest-growing yeasts on diluted hydrolysate. S. stipitis CBS 5773 demonstrated a low growth and biomass production while consuming glucose, while during the xylose-phase, the specific growth and sugar co-consumption rates were among the highest of this study (0.17 h(-1) and 0.37 g/gdw{*
Biomass pretreatment can improve the conversion efficiency of bioenergy production. Liquid hot water (LHW) pretreatment is a truly green pretreatment due to its zero chemical use, but has the disadvantages of low lignin removal and pseudo-lignin formation. A modified liquid hot water (MLHW) process based on in situ synthesis of deep eutectic solvent (DES) could efficiently improve delignification of Roystonea regia leaves (LR) and leaf sheaths (LSR). LSR was less recalcitrant than LR, and its characteristics of higher porosity (34.8\%) and thinner cell walls (5.2 mu m) for LSR contributed it higher lignin removal (53.6\%) and lower choline chloride (ChCl) consumption (H2O-ChCl mass ratio of 2:1) than those (44.6\% and 1:2) from LR. Moreover, a great improvement of 309.0\% in bio-methane yield was achieved for the MLHW-treated LSR. In addition, in situ DES in MLHW had good biocompatibility with cellulase, microalgae, and yeast.
In the wake of rising demand for water as well as widespread unavailability of resources for employment of conventional water treatment techniques, the use of adsorption involving agricultural waste derived biosorbents has become a desired alternative. However, in their natural state, these agro-biosorbents exhibit low sorption capacity thereby raising the need for physical and/or chemical modification for improvement. Mangifera indica (mango) seed shell powder was modified by treatment with sodium hydroxide solution followed by surface functionalization with ethylenediaminetetraacetic (EDTA) dianhydride. The natural and modified mango materials were characterized by Fourier transform infra-red spectroscopy (FTIR), elemental, thermogravimetric and X-ray diffraction analysis. The performance of the carboxyl functionalized mango biosorbent (CFMS) was tested against that of the alkali treated mango biosorbent (ATMS) for removal of lead(II) ions from aqueous solutions through batch adsorption experiments. Binding mechanism elucidation through FTIR and thermogravimetric analysis demonstrated chelation by the grafted EDTA ligands. The effects of contact time and initial lead(II) ion concentration were evaluated. The Langmuir, Freundlich and Dubinin-Radushkevich models were used to study the adsorption isotherms while the pseudo-first order, pseudo-second order, Elovich, Bangham's and intra-particle diffusion models were used for the simulation of sorption kinetics. The isotherms were best simulated by the Langmuir model and the adsorption capacity of ATMS was 59.25 mg g(-1) whereas that of CFMS was 306.33 mg g(-1). Sorption kinetics were well simulated by the pseudo-second order model. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Recent years witnessed the dawn of the cellulosic ethanol industry based on enzymatic hydrolysis of carbohy-drates in lignocellulosic biomass. Meanwhile, new concepts have emerged to depolymerize lignin and upgrade the obtained lignin fragments into value-added fuels and chemicals. This review analyzes the convergence of these two fields, presenting the opportunities for applying such depolymerization technologies to the residual enzymatic hydrolysis lignin (EHL) now available at an industrial scale. Key characteristics of EHL are presented together with the most investigated technologies for EHL depolymerization (pyrolysis, hydrothermal, and sol-volysis) to obtain lignin bio-oils. The review also discusses the prospects for upgrading lignin bio-oils for use as aviation and marine biofuels. Furthermore, it presents a more long-term vision that progressively valorizes the biochar by-product and adds the co-production of chemicals harnessing the aromaticity and oxygenation of the lignin moieties. In conclusion, EHL has a unique set of characteristics (cost, availability, transportability, degrees of oxygenation and purity, reactivity, among others) to produce lignin bio-oils, instigating research questions dedicated to this type of industrially relevant feedstock.
The hemicellulosic fraction recovery is of interest for integrated processes in biorefineries, considering the possibility of high economic value products produced from their structural compounds of this polysaccharide. However, to perform an efficient recovery, it is necessary to use biomass fractionation techniques, and hydrothermal pretreatment is highlighted as a valuable technique in the hemicellulose recovery by applying high temperatures and pressure, causing dissolution of the structure. Considering the possibility of this pretreatment technique for current approaches to hemicellulose recovery, this article aimed to explore the relevance of hydrothermal pretreatment techniques (sub and supercritical water) as a strategy for recovering the hemicellulosic fraction from lignocellulosic biomass. Discussions about potential products to be generated, current market profile, and perspectives and challenges of applying the technique are also addressed.
Influences of two types of substrates, natural (macrophyte, Pistia stratiotes) and artificial (plastic screen) were evaluated at 3 differrent densities (10, 20, 30\%) on periphyton development, water quality and growth performance of jaraqui (Semaprochilodus insignis). Fish of average initial weight 1.46-1.69 g and length 4.15-4.26 cm stocked at 1/m(2) in 46 m(2) masonry tanks were grown for 120 days. The tanks were fertilized with urea, triple superphosphate and wheat bran. The types and densities of substrates tested did not drastically influence water quality. Natural substrate harboured higher periphyton biomass (1.48 +/- 0.09 mg/cm(2)) as well as species diversity (28 genera) than the artificial substrate (0.84 +/- 0.12 mg/cm(2), 20 genera). Fish in 10\% and 20\% artificial substrate and 20\% natural substrate treatments showed better mean values of body weight (24.64, 23.86, 29.26 g respectively) on termination of the experiment. Fish survival was the lowest in 30\% natural substrate (84.1\%) and highest in 10\% artificial substrate (94.2\%). Higher fish biomass was recorded in 20\% natural and 10\% artificial substrate treatments (25.05 and 21.71 g/m(2)), which amounts to a four-month yield of 250 and 217 kg/ha in the two treatments.
The cellulose from agroindustrial waste can be treated and converted into nanocrystals or nanofibers. It could be used to produce biodegradable and edible films, contributing to the circular economy and being environmentally friendly. This research aimed to develop an edible film elaborated with activated cellulose nanocrystals, native potato starch, and glycerin. The activated cellulose nanocrystals were obtained by basic/acid digestion and esterification with citric acid from corn husks. The starch was extracted from the native potato cultivated at 3500 m of altitude. Four film formulations were elaborated with potato starch (2.6 to 4.4\%), cellulose nanocrystals (0.0 to 0.12\%), and glycerin (3.0 to 4.2\%), by thermoforming at 60 degrees C. It was observed that the cellulose nanocrystals reported an average size of 676.0 nm. The films mainly present hydroxyl, carbonyl, and carboxyl groups that stabilize the polymeric matrix. It was observed that the addition of cellulose nanocrystals in the films significantly increased (p-value < 0.05) water activity (0.409 to 0.447), whiteness index (96.92 to 97.27), and organic carbon content. In opposition to gelatinization temperature (156.7 to 150.1 degrees C), transparency (6.69 to 6.17), resistance to traction (22.29 to 14.33 N/mm), and solubility in acidic, basic, ethanol, and water media decreased. However, no significant differences were observed in the thermal decomposition of the films evaluated through TGA analysis. The addition of cellulose nanocrystals in the films gives it good mechanical and thermal resistance qualities, with low solubility, making it a potential food-coating material.
The level of nitrate in water has been increasing considerably all around the world due to vast application of inorganic nitrogen fertiliser and animal manure. Because of nitrate's high solubility in water, human beings are getting exposed to it mainly through various routes including water, food etc. Various regulations have been set for nitrate (45-50 mgNO(3)(-)/L) in drinking water to protect health of the infants from the methemoglobinemia, birth defects, thyroid disease, risk of specific cancers, i.e. colorectal, breast and bladder cancer caused due to nitrate poisoning. Different methods like ion exchange, adsorption, biological denitrification etc. have the ability to eliminate the nitrate from the aqueous medium. However, adsorption process got preference over the other approaches because of its simple design and satisfactory results especially with surface modified adsorbents or with mineral-based adsorbents. Different types of adsorbents have been used for this purpose; however, adsorbents derived from the biomass wastes have great adsorption capacities for nitrate such as tea waste-based adsorbents (136.43 mg/g), carbon nanotube (142.86 mg/g), chitosan beads (104 mg/g) and cetyltrimethylammonium bromide modified rice husk (278 mg/g). Therefore, a thorough literature survey has been carried out to formulate this review paper to understand various sources of nitrate pollution, route of exposure to the human beings, ill effects along with discussing the key developments as well as the new advancements reported in procuring low-cost efficient adsorbents for water purification.
Sonication (or ultrasound irradiation) has emerged as a potential technique for the intensification of diverse physical/chemical/biological processes. In recent years, sonication has been applied in the synthesis of liquid biofuels, such as biodiesel, and bioalcohols, such as ethanol. The process of bioalcohol synthesis comprises four steps, viz. acid pretreatment, alkaline delignification, enzymatic hydrolysis and fermentation. Significant literature has been published in the last decade on the application of ultrasound for the intensification of all the steps of bioalcohol synthesis. In this paper, a critical review and analysis of the literature on ultrasound-assisted bioalcohol synthesis has been presented. This review has addressed all four steps of bioalcohol synthesis. Essentially, the literature in the areas of ultrasound-assisted biomass pretreatment, delignification and hydrolysis has been reviewed, followed by an analysis of the literature on ultrasound-assisted fermentation. Finally, the mechanistic investigations of the various steps of bioalcohol synthesis have been reviewed, highlighting the synergistic links between the physical/chemical effects of ultrasound and cavitation and the basic physical/chemical mechanisms of the steps of bioalcohol synthesis. The critical analysis of the literature in this review has not only demonstrated the efficacy of ultrasound in the intensification of all the steps of bioalcohol synthesis, but has also brought to light the underlying mechanistic issues; this could provide guidelines for the design and optimization of commercial scale bioalcohol processes.
In the present work, four types of newly chosen municipal solid wastes (Panax ginseng, spent tea residue, waste cotton cloth, and old corrugated cardboard) were studied as the promising sources for nanocellulose, which has efficiently re-engineered the structure of waste products into highly valuable nanocellulose materials. The nanocellulose was produced directly via a facile one-pot oxidative hydrolysis process by using H2O2/Cr(NO3)(3) solution as the bleaching agent and hydrolysis medium under acidic condition. The isolated nanocellulose products were well-characterized in terms of chemical composition, product yield, morphological structure and thermal properties. The study has found that the crystallinity index of the obtained nanocellulose products were significantly higher (62.2-83.6\%) than that of its starting material due to the successive elimination of lignin, hemicellulose and amorphous regions of cellulose, which were in good agreement with the FTIR analysis. The evidence of the successful production of nanocellulose was given by TEM observation which has revealed the fibril widths were ranging from 15.6 to 46.2 nm, with high cellulose content (>90\%), depending on the cellulosic origin. The physicochemical properties of processed samples have confirmed that the isolation of high purity nanocellulose materials from different daily spent products is possible. The comparative study can help to provide a deep insight on the possibility of revalorizing the municipal solid wastes into nanocellulose via the simple and versatile one-pot isolation system, which has high potential to be used in commercial applications for sustainable development. (C) 2017 Elsevier B.V. All rights reserved.
Biorefineries are considered as an integrative thinking that focuses on the possibility of obtaining as many added-value products as technically and economically feasible. However, in practice most biorefineries comprise only enzymatic or chemical pretreatment followed by biofuel generation. The drop in oil prices may menace the development of this young industry, as has happened before in history. This has become a fundamental reason for which the biofuel industry should not consider only biofuels production, but enzyme and non-fuel based chemicals as well. Hence, this work aims at overviewing the most important enzymes involved in biotechnological processes and to describe their role in biorefineries. Bioethanol, biogas and biodiesel biorefineries are overviewed, along with the integrated and industrial types. Finally separation and purification processes in biorefineries are discussed. (C) 2016 Society of Chemical Industry
In this study, date palm fibres and orange peel in both individual and hybrid forms were studied for the removal of copper, lead, and arsenic. Equilibrium was achieved after 150 minutes, and the highest and the lowest removal efficiencies were for Cu+2 and As(V), respectively. A slightly higher removal efficiency of metal ions using orange peel was observed, which could be due to the greater number of functional groups on the chemically pre-treated adsorbent. The highest removal was observed at pH 6, and the adsorption data exhibited a linear increase in metal removal capacity with increasing adsorbent concentrations from 0.1 to 2 g/L. A significantly higher removal efficiency was observed for a 45 gm particle size compared to larger particle sizes. Additionally, a 30-40\% decrease in removal efficiencies was observed for all three heavy metal ions when using the date palm fibres or the hybrid adsorbent when the initial metal concentrations were increased from 20 to 80 mg/L. The Freundlich model agreed with the experimental data slightly better than the Langmuir model for both date palm fibres and the hybrid adsorbent. A pseudo second-order kinetic model better described the kinetic behaviour of As(V) adsorption on the investigated adsorbents. Date palm fibres exhibited exothermic adsorption, while both orange peel and the hybrid adsorbent displayed exothermic and endothermic reactions. Increased randomness at the solid-liquid interface was observed for all adsorbents, and the Gibbs free energy change values were negative, confirming the spontaneous nature of adsorption, which proceeded in the forward direction.
In this work the electrooxidations of glucose, galactose, mannose, rhamnose, xylose and arabinose are studied at a nickel hydroxide nanoparticle modified boron-doped diamond electrode and compared to an unmodified electrode. These carbohydrates are very important in the second-generation ethanol production process. Nickel hydroxide modified boron-doped diamond was characterized by scanning electron microscopy and energy dispersive X-ray. Electrochemical impedance spectroscopy was employed to study the interface properties of surface-modified electrodes in the absence and presence of the carbohydrates. Limits of detection were 5.3 x 10(-5), 6.8 x 10(-5), 2.7 x 10(-4), 6.9 x 10(-5), 8.8 x 10(-5) and 2.6 x 10(-5) mol L-1 for glucose, galactose, mannose, rhamnose, arabinose, xylose, respectively.
It is imperative to search for appropriate processes to convert wastes into energy, chemicals, and materials to establish a circular bio-economy toward sustainable development. Concerning waste biomass valorization, hydrothermal carbonization (HTC) is a promising route given its advantages over other thermochemical processes. From that perspective, this article reviewed the HTC of potential biomass wastes, the characterization and environmental utilization of hydrochar, and the biorefinery potential of this process. Crop and forestry residues and sewage sludge are two categories of biomass wastes (lignocellulosic and non-lignocellulosic, respectively) readily available for HTC or even co-hydrothermal carbonization (Co-HTC). The temperature, reaction time, and solid-to-liquid ratio utilized in HTC/Co-HTC of those biomass wastes were reported to range from 140 to 370 degrees C, 0.05 to 48 h, and 1/47 to 1/1, respectively, providing hydrochar yields of up to 94 \% according to the process conditions. Hydrochar characterization by different techniques to determine its physicochemical properties is crucial to defining the best applications for this material. In the environmental field, hydrochar might be suitable for removing pollutants from aqueous systems, ameliorating soils, adsorbing atmospheric pollutants, working as an energy carrier, and performing carbon sequestration.
The interest in pneumatic bioreactors is related to their good mass transfer capacity, as well as lower operating costs, due to the simple mechanical structure. Knowledge of the transport phenomena and hydrodynamics of bioreactors is important to enable definition of the best bioreactor model and operating conditions for a specific bioprocess, with the imposed shear being one of the most difficult to quantify. For stirred tanks, the fragmentation of microorganisms has been well correlated with a hydrodynamic parameter called the ``energy dissipation/circulation function{''
More than 170 million individuals have been influenced by arsenic (As) because of the ingestion of As-polluted groundwater. The presence of As in water bodies, particularly groundwater, has been found to become a widespread issue in the past few decades. Because arsenic causes extreme wellbeing impacts, even at a low concentration in drinking water, the innovations of As removal from contaminated water are of significant importance. Traditional strategies, for example, reverse osmosis, ion exchange, and electro-dialysis are generally utilized for the remediation of As-polluted water; however, the high cost and/or sludge production restricts their application in less-developed areas. The utilization of adsorbents acquired from natural materials has been explored as an alternative for the costly techniques for As removal. This paper aims to review the past and current developments in using naturals adsorbents or modified natural materials for arsenic removal and show the different parameters, which may influence the As removal effectiveness of the natural adsorbent, such as contact time, adsorbent dosage, flow rate, pH, reusability, temperature, and influence of others ions.
Cellulose accessibility has been proposed as a key factor in the efficient bio-conversion of lignocellulosic biomass to fermentable sugars. Factors affecting cellulose accessibility can be divided into direct factors that refer to accessible surface area of cellulose, and indirect factors referring to chemical composition such as lignin/hemicellulose content; and biomass structure-relevant factors (i.e. particle size, porosity). An overview of the current pretreatment technologies special focus on the major mode of action to increase cellulose accessibility as well as multiple techniques that could be used to assess the cellulose accessibility are presented in this review. The appropriate determination of cellulose accessibility before and after pretreatment can assist to understand the effectiveness of a particular pretreatment in overcoming lignocellulosic recalcitrance to improve substrate enzymatic digestibility.
Hemicelluloses, a major component of plant cell walls, are a non-cellulosic heteropolysaccharide composed of several distinct sugars that is second in abundance to cellulose, which are one of the most abundant and cheapest renewable resources on earth. Hemicelluloses structure is complex and its chemical structure varies greatly among the different plant species. In addition to its wide use in production of feed and other chemical materials, hemicelluloses are known for its remarkable biological activities that remain largely underutilised to date. Therefore, comprehensive investigations of hemicelluloses structural and biological properties would be helpful for achieving rational utilisation and high-value conversion of this underutilised substance into agents with enhanced health benefits for incorporation in drugs and health foods. In this review, details of diverse research initiatives that have enhanced our understanding of hemicelluloses properties are summarised, including hemicelluloses sources, extraction and purification methods, structural characteristics and biological activities. Furthermore, hemicelluloses structure-activity relationships and new directions for future hemicelluloses research studies are discussed.
This study reported the desorption of adsorbed crystal violet (CV) dye on the argan nutshell (ANS) and almond shell (AS) using nitric acid (HNO3) as a desorbing agent and their reusability to remove the CV in multiple consecutive adsorption-desorption cycles. The prepared adsorbents were characterized using FTIR and SEM analysis. Different desorbing agents (HCl, HNO3, H3PO4, CH3COOH, NaOH, H2O, H2O (pH = 2), and H2O (pH = 11)) were tested to determine the best eluent. The effect of experimental parameters, such as CV-adsorbent dose (4-40 g L-1), contact time (0-180 min), and HNO3 concentration (0.01-2 M) on the desorption of the CV from CV-ANS and CV-AS was studied. The HNO3 (0.1 M) solution was an excellent eluent for the CV desorption from CV-ANS (98.21\%) and CV-AS (98.60\%) using 16 g L-1 of CV-adsorbent dose at 23 +/- 1 degrees C for 60 min. The pseudo-second-order kinetic model well-exemplified experimental data. Excellent regeneration reusability of ANS and AS for the CV removal for six consecutive adsorption-desorption cycles. This study showed that argan nutshell and almond shell as low-cost adsorbents have tremendous potential for removing the CV in multiple consecutive adsorption-desorption cycles as an alternative eco-friendly process.
The conversion of lignocellulosic biomass (LB) to sugar is an intricate process which is the costliest part of the biomass conversion process. Even though acid/enzyme catalysts are usually being used for LB hydrolysis, enzyme immobilization has been recognized as a potential strategy nowadays. The use of nanobiocatalysts increases hydrolytic efficiency and enzyme stability. Furthermore, biocatalyst/enzyme immobilization on magnetic nanoparticles enables easy recovery and reuse of enzymes. Hence, the exploitation of nanobiocatalysts for LB to biofuel conversion will aid in developing a lucrative and sustainable approach. With this perspective, the effects of nanobiocatalysts on LB to biofuel production were reviewed here. Several traits, such as switching the chemical processes using nanomaterials, enzyme immobilization on nanoparticles for higher reaction rates, recycling ability and toxicity effects on microbial cells, were highlighted in this review. Current developments and viability of nanobiocatalysts as a promising option for enhanced LB conversion into the biofuel process were also emphasized. Mostly, this would help in emerging eco-friendly, proficient, and cost-effective biofuel technology.
Rapid population growth and the resultant pollution of freshwater sources are expected to create water stress conditions on the world in the near future. Adsorption technique is a popular method in reducing the amount of pollutants that enter water bodies, and researchers are focusing on development of activated carbons from cheap sources to replace costly commercial activated carbons. Remediation of wastewater using activated carbon from biowaste (defined in this paper as waste material derived from living organisms or of organic origin, and capable of decomposing under anaerobic or aerobic conditions) is gaining attention among researchers, as such technology reduces the cost of activated carbon production while reducing the cost on biowaste disposal. This paper summarizes recent development and findings on application of activated carbon synthesized from biowaste in wastewater treatment. Adsorption efficiencies of newly developed activated carbons in treatment of different pollutants (including dyes, metal ions, pharmaceutical and personal care products, organic pollutants) in simulated and real wastewater are also tabulated for easy reference. The potential of activated carbons modified with magnetic materials is also discussed, followed by recent advances and challenges in applications of activated carbons derived from biowaste in wastewater treatment. (C) 2017 Elsevier Ltd. All rights reserved.
In this work, the biosorption of Cr3+ and Ni2+ by Sargassum filipendula pre-treated with CaCl2 was studied. Kinetic and equilibrium experiments were carried out for mono- and multi-component solutions in a batch reactor at pH 3.0 and 30 degrees C. The results from the kinetic experiments showed that Cr3+ adsorbs slower than Ni2+. This behavior was explained by means of a mechanistic analysis, which showed that Cr3+ uptake presented three adsorption stages, whereas Ni2+ adsorption presents only two. The mono- component equilibrium data, along with binary kinetic data obtained from mono- component experiments, showed that, although the kinetics for Cr3+ removal are slower, the biomass had a stronger affinity for this ion. Almost all Ni2+ is desorbed from the biomass as Cr3+ adsorbs. The binary equilibrium data also presented this behavior. The binary data was also modeled by using modified forms of the Langmuir, Jain and Snoeyink, and Langmuir-Freundlich isotherms. However, the prediction obtained presented low accuracy. An alternative modeling with artificial neural networks was presented and the results showed that this technique could be a promising tool to represent binary equilibrium data. The main contribution of this work was to obtain experimental data for Cr3+/Ni2+ adsorption, which is a system rarely found in the literature and that provides information that could be used in process modeling and simulation.
Lignocellulose, the main component of plant cell walls, comprises polyaromatic lignin and fermentable materials, cellulose and hemicellulose. It is a plentiful and renewable feedstock for chemicals and energy. It can serve as a raw material for the production of various value-added products, including cellulase and xylanase. Cellulase is essentially required in lignocellulose-based biorefineries and is applied in many commercial processes. Likewise, xylanases are industrially important enzymes applied in papermaking and in the manufacture of prebiotics and pharmaceuticals. Owing to the widespread application of these enzymes, many prokaryotes and eukaryotes have been exploited to produce cellulase and xylanases in good yields, yet yeasts have rarely been explored for their plant-cell-wall-degrading activities. This review is focused on summarizing reports about cellulolytic and xylanolytic yeasts, their properties, and their biotechnological applications.
Biocomposites developed from lignocellulosic biomass have numerous potential applications in various sectors, including food packaging and medical technologies, wastewater treatment and purification. However, since the physicochemical properties of biocomposites are inferior to synthetic composites in various applications, it has been imperative to enhance their properties, by employing chemical and physical methods to modify their surface chemistry. In most cases, chemical methods have frequently been used due to the ability to form the intramolecular and intermolecular bonds between the polymers and the modifiers. The aim of this review is to evaluate different methods used in the preparation of bio-composites, mainly those that are comprised of lignocellulosic derivatives and chitosan biopolymer. In addition, the review will critically looks at biocomposites as biosorbent materials in the removal of organic and inorganic contaminants in aqueous solutions by investigating the different classes, different methods of preparation, their advantages, limitations and efficiency. The review will also survey the different applications particularly the success in their deployment in the water purification and treatment.
Composting is considered an economically-friendly procedure for producing commercial solid organic amendments and fertilisers from the two-phase olive mill waste (called ``alperujo{''
The development of biodegradable food packaging with superior properties and functionalities compared to conventional food packaging is one of the emerging research interests. Immediate disposal of conventional single use nonbiodegradable food packaging results in adverse environmental impact. Utilization of either biomass-based, microorganism-derived, or biotechnologically synthesized biopolymers as biodegradable matrices is the common approach toward achieving sustainability. Consequently, starch and cellulose are being commonly used as biodegradable matrices. However, rather than being fully biodegradable, most of them can be considered as semibiodegradable. Majority of the review studies are based on matrices that have an origin in edible sources, which might result in food insecurity. Although development of bio-based polymers with sound packaging properties have been extensively studied, the potential agro-industrial waste as alternative, eco-friendly, and economically viable matrices have attracted little attention. Therefore, the approaches of developing biodegradable food packaging and the framework of converting agro-industrial waste into biodegradable packaging matrices are discussed comparatively in this paper. It also critiques the approaches and valorization of agro-industrial waste in biodegradable food packaging. Thereby, an overview of physicochemical, functional, and biodegradable properties of commonly used biodegradable food packaging materials are provided as an insight for agro-industrial waste-based food packaging. The potential use of agro-industrial waste-based biodegradable food packaging materials against commonly used biodegradable food packaging materials has been highlighted in this study. Thereby, the vital necessity of growing awareness about agro-industrial waste as biodegradable food packaging materials is emphasized through this comprehensive review.
Microbial secondary metabolites (SMs) are the intermediate or the product of metabolism produced during fermentation process. SMs are produced during stationary phase and play a major role in competition, antagonism and self defence mechanisms. These metabolites finds application in the pharmaceuticals, food, cosmetics etc. These are produced besides primary key metabolites (e.g., amino acids, lipids, carbohydrates etc.). Growth condition in solid-state fermentation (SSF) resembles microorganism's own native environment allowing the microorganisms to adapt best. Recent developments in bioprocessing has identified specific SSF practices that have a significant impact on SMs production. The practice of SSF, representing new opportunities to design better bioprocessing with potential genetic development goals for expanding the list of exciting SMs. Current updates cover advanced techniques on SSF to improve microbial SMs production and their ease of operation and costeffective production strategies. Various factors affecting the SSF have been discussed with respect to sustainable development of novel SSF strategies for SMs production.
The increasing demand for sustainable bioproducts as alternatives to fossil-based resources requires unremitting endeavor for the advancement of lignocellulose valorization. In this respect, the robust pretreatment of lignocelluloses has been deemed as an essential process for high component fractionation performance to facilitate downstream upgrading. This review thereby presents the current state-of-the-art amine-based pretreatments of lignocellulosic biomass. The pretreatment role as well as the concept and features of amine-based pretreatment is first described to ensure the effectiveness of component fractionation and biorefinery of lignocelluloses. A deep mechanistic understanding of pretreatment and its performance is fully described to aid in achieving a high yield of fermentable sugars while leaving preferred lignin for further upgradation. Furthemore, numerous amine solvent systems of pretreatment are reviewed to present their potential benefits in the fractionation process with effective separation of interlinked lignocellulose components, yield and the quality of fractionates. Moreover, some existing challenges and perspectives are indicated to highlight opportunities within this captivating technology. Amine-based pretreatment could be a promising approach with distinct beneficial attributes on lignocellulose conversion and lignin valorization.
Hybrid reinforced particulate aluminum matrix composite materials (HAMCs) are a breakthrough kind of material made by combining two or more distinct reinforcing components in the aluminum (Al) matrix. Composites with many reinforcing phases offer a superior overall mix of characteristics than composites with only one. This article's wide literature review of metal matrix composite (MMC) especially for aluminum matrix composites (AMC) was carried out. Discussions of various widely adopted synthesis methods such as stir casting and powder metallurgy have been presented. The effect of various reinforcement ceramic particles such as silicon carbide (SiC), aluminum oxide (Al2O3), graphite (Gr) on the mechanical and metallurgical properties of MMC has been reviewed. The summary of various characterizations such as X-ray diffraction (X-RD), and optical microscopy (OM) including testing such as hardness, tensile, compressive, and tribological behavior has been discussed in detail to demonstrate a full grasp of the many features of HAMCs, such as manufacturing, physicomechanical properties, wear, and corrosion characteristics. Future developments and potentially useful materials as alternative reinforcements are discussed at the end of the review.
Recently, the demand for biodegradable, eco-friendly and sustainable alternatives has been on the increase. Although numerous biopolymers such as cellulose, starch, plants proteins and polylactic acid, etc., have been used to produce bioplastics, the outcomes need more improvement to suit different applications. This paper comprehensively maps the expanding academic territory using lignin as a reinforcement material to improve biopolymers-based materials' properties. A brief discussion on the chronological development of lignin, types, isolation, physical and chemical modifications was presented. Also, the role of lignin in biopolymeric blends such as starch, polylactic acids, plants proteins, polyhydroxy butyrate and polyamides was reviewed. Finally, the review extensively and critically discusses the current findings on lignin/biopolymers blends in various industrial applications, including wood adhesives, adsorbent for toxic heavy metal removal, production of carbon materials, dispersant medium, flame retardant and storage materials, etc., and highlighted the possible applications of lignin in biofuel, hydrocarbon, lubricant, renewable chemical, and smart materials. (c) 2021 The Author(s). Published 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/).
This article discusses the environmental sustainability of bio-based or green chemicals and highlights various factors determining their ``level of greenness{''
Water hyacinth hydrolysate is problematic for lipid overproduction due to the undesirable low carbon-to-nitrogen ratio (C/N) and the presence of inhibitory compounds. Crude glycerol is routinely provided with extremely deficient of some essential nutrients, which disfavors cell growth and lipid overproduction. Here a simple combination utilization of these two low-cost substrates was developed to realize mutual achievement for the oleaginicity of Cutaneotrichosporon oleaginosum. The lipid titer of 15.6 g/L, lipid content of 58.1\%, and lipid yield (Y-L/S) of 0.24 g/g were achieved, when 10\% (v/v) of water hyacinth enzymatic hydrolysate (WHEH) and crude glycerol were simply mixed without any other treatments. These data were dramatically superior to those of separate utilization of these two substrates. The C/N was optimized through appropriate mixing of these two substrates and the toxic effect was alleviated through dilution detoxification. Lignocellulosic sugars and amino acids could cooperate with crude glycerol to promote lipogenesis. The fatty acid composition and the prediction of biodiesel parameters of lipids produced by the combination strategy indicated the suitability for the production of high-quality biodiesel. The combined utilization method offers an extremely simple and cost-effective scheme for lipogenesis from crude glycerol and nitrogen-rich biomass hydrolysates, which should foster better techno-economic routes of lipid production from low-cost substrates.
Carbon materials are versatile in nature due to their unique and modifiable surface and ease of production. Nanostructured carbon materials are gaining importance due to their high surface area for application in the energy, biotechnology, biomedical, and environmental fields. According to their structures, carbon allotropes are classified as carbon nanodots, carbon nanoparticles, graphene, oxide, carbon nanotubes, and fullerenes. They are synthesized via several methods, including pyrolysis, microwave method, hydrothermal synthesis, and chemical vapor deposition, and the use of renewable and cheaper agricultural feedstocks and reactants is increasing for reducing cost and simplifying production. This review explores the nanostructured carbon detailed investigation of sources and their relevant reports. Many of the renewable sources are covered as focused here, such as sugar cane waste, pineapple, its solid biomass, rise husk, date palm, nicotine tabacum stems, lapsi seed stone, rubber-seed shell, coconut shell, and orange peels. The main focus of this work is on the various methods used to synthesize these carbon materials from agricultural waste materials, and their important applications for energy storage devices, optoelectronics, biosensors, and polymer coatings.
Biohydrogen produced from cellulosic feedstock is a promising candidate for future energy needs as a renewable energy carrier. The thermochemical route and biological processes have great potential for biohydrogen production. In particular, pyrolysis/gasification and dark fermentation are the methods to enhance the biohydrogen production from cellulose. The review compiles the essential information on both processes, including pretreatment of cellulose since it has a complex structure. The operating conditions for both processes, for example, the influence of cellulose pyrolysis/gasification such as temperature, heating rate, and vapor residence time, while for dark fermentation, including the temperature, inoculum source, hydraulic retention time, and pH, are discussed. The bioreactor configurations and economic aspects of both processes are also discussed. The review aims are to present the current state of knowledge about the two processes using cellulose as substrates. Surprisingly, dark fermentation is a promising method for application of cellulose for biohydrogen production since many works were done on dark fermentation compared to pyrolysis/gasification. The future perspectives on enhancing hydrogen production from cellulose have also been discussed.
The present work deals with the application of response surface methodology (RSM) to study the effects of various operational parameters on the decolorization of Congo red (CR) from dye wastewater. The live fungal biomass of Neurospora crassa along with wheat bran was used as a dual adsorbent for the removal of CR color from aqueous solution. Decolorization experiments were conducted in batch mode by varying experimental factors such as initial pH, initial dye concentration, wheat bran dosage, live biomass dosage, wheat bran particle size, and agitation speed. The process parameters were optimized using central composite design (CCD) to attain the maximum percentage decolorization. Predicted values of percentage color removal were found to be in good agreement with experimental values, which indicates that the suitability of the model and the success of CCD in optimization of CR color removal process. Graphical response surface and contour plots were used to locate the optimum points. The regression model equation for percentage CR color removal was established. The optimum pH, dye concentration, wheat bran dosage, live biomass dosage, wheat bran particle size and agitation speed were found to be 6, 200 mg L-1, 12.5 g L-1,2\% (w/v), 150 mu m, 150 rpm, respectively for CR color removal. Further, the batch experiments were conducted to study the effect of electrolytes, surfactants, mixture of dyes, and temperature on dye decolorization. We concluded that the live fungal biomass of Neurospora crassa with wheat bran was shown to be suitable dual adsorbent for adsorption of CR and it can be used effectively in wastewater treatment.
The mechanical and thermal properties of clay bricks are important parameters that influence the durability and energy consumption of building bricks in service. This study investigates the influence of waste glass when combined with coconut shells on the properties of burnt bricks. Particulate coconut shell (PCS) of -75 mu m was added to Orita-Obele clay at a varied proportion of clay (0\%-2\%), while waste glass (-75 mu m) was utilized at a constant proportion (25\% by weight of clay). The physical, mechanical, and thermal properties of the samples were evaluated as well as efflorescence. The surface morphology of each weight fraction was examined under a scanning electron microscope. From the results obtained, the samples evaluated exhibited reduced porosity, water absorption, initial rate of suction, efflorescence, and wear characteristics. Moreover, the linear shrinkage, bulk density, compressive strength, modulus of rupture, hardness, and thermal conductivity were observed to increase with the addition of waste glass and particulate coconut shell. All samples produced satisfied the minimum strength requirement for masonry application. Hence, PCS and waste glass can be combined in the production of fired masonry bricks.
In the present study, we pretreated the plant Guinea grass (Panicum maximum) with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate {[
We report, the catalytic application of sulphonated cellulose based solid carbon catalyst for conversion of oleic acid to methyl oleate-biodiesel production under microwave irradiation. Oleic acid, being one of the most widely found fatty acids in plant oils and animal fats; it was utilized as a model substrate to produce biodiesel in this study. The effect and interaction of four independent factors such as methanol to oleic acid molar ratio (MOMR), time, catalyst loading, and temperature were investigated using response surface methodology (RSM). After doing the thirty experiments given by the central composite design (CCD), the optimized reaction condition using RSM was found to be MOMR of 21:1, 60 min, 8 wt \% catalyst loading, and temperature of 80 degrees C that predicted 96.77\% biodiesel yield under microwave irradiation, whereas, 97.6 +/- 0.2\% yield was observed experimentally. The kinetic study of the esterification reaction showed that it followed a pseudo first order reaction. The acti-vation energy of the esterification was found to be relatively low at 49.19 kJ mol-1. The catalyst showed good recyclability when explored up to the 5th reaction cycle. The SEM analysis of the recycled catalyst showed its stability for at least 5 reaction cycles. Therefore, it can be promoted for sustainable production of biodiesel due to its moderate preparation method, good catalytic efficiency, and excellent recyclability.
Commercially available supercapacitors offer very limited advantages over other energy storage devices. Balancing their electrochemical performance such as capacitance, energy density, and cyclability is challenging. Studies have shown that this challenge can be overcome by using light and cheap substrates that are highly stable with solvents, and have high loading capacities and compatibility with nanomaterials. Nanocellulose, derived from wastes or biomass, is a good candidate for integrating with other nanosize conductive materials, such as carbon, conducting polymers, and metal oxides, as active materials or nanocomposites for supercapacitors. This review focuses on the properties and preparation of nanocellulose sourced from wastes (biomass) and bacteria, and extends to emerging materials, such as metal-organic frameworks and MXene, for nanocellulose-based supercapacitors. Even though supercapacitors are mainly composed of electrodes, electrolytes, and separators, this paper focuses on the overall electrochemical performance of nanocellulose-based supercapacitors to evaluate the influence of nanocellulose. In addition, the potentials and possible limitations of nanocellulose in supercapacitors are discussed. Overall, the incorporation of waste-derived nanocellulose into energy storage applications is an initiative that improves the circular economy and supports environmental sustainability.
The hydroxyl groups adjacent to the beta-1,4 glycosidic linkages in cellulose offer a crystalline structure, which makes depolymerization a difficult task. In the present study, a green synthesized nanomaterial, functionalized few-layer graphene (FFG) possessing exclusive cellulase enzyme mimicking properties, was exploited for the depolymerization of corn cob (CC)-derived cellulose moieties. Here, we studied the combined effect of cellulase and a very low concentration of FFG (0.02 wt\% of biomass) on CC-derived cellulose hydrolysis, demonstrating 38\% increase in hydrolysis compared to the control (i.e. without FFG). Most importantly, hydrolysis experiments were performed under mild conditions, i.e. at 50 degrees C, generating fermentable sugars without the formation of any inhibitor compounds. Furthermore, hydrolyzed CC cellulose was employed for bioethanol fermentation by Saccharomyces cerevisiae which produced 1.53 times higher ethanol in the presence of FFG. The residual solid part was further utilized for the formation of cellulose based nano-composite films. Here, we tried to develop a zero waste process by utilizing each component which can be an attractive sustainable option. To the best of our knowledge, this is the first report on the cellulase mimicking activity of FFG nanosheets and their application in the hydrolysis of CC cellulose for improved bioethanol production, which can negate the need for costly cellulase enzymes required for biomass hydrolysis. Hence, the FFG-associated biomass to bioethanol process may pave the way toward the development of green sustainable biofuel technology for its foremost use as transport fuel.
The hazard of oil pollution has increased with the growth of industrial development and exploration, production, and refining of oil. Due to the recent increase in the volume of oily wastewater worldwide, the outcome and effect of discharging contaminated water into the environment have become significant issues of environmental concern. Thus, the treatment of oily water is critical for environmental protection. Oily water is conventionally treated through different physical, chemical, and biological methods. However, most of the conventional treatment technologies fail to remove small suspended oil content and dissolved elements; moreover, many chemical treatments involve high initial and/or running costs and lead to the production of hazardous sludge, which is released into offshore platforms because of space constraints. This highlights the need for compact physical and chemical systems. Among the various methods proposed for the treatment of oily water, adsorption is an attractive option because of its excellent oil-removing ability, eco-friendliness, cost-effectiveness, easy availability, feasibility, universal applicability, and relieves operation. The present article describes the effectiveness of hydrophobic adsorbents, their application to oil-spill cleanup, and the toxic effects of oily water on human health and the environment. In addition, we have also attempted to elucidate the available cost-effective adsorbent techniques and future perspectives of economical adsorbents for oily water treatment.
The study proposes a novel and sustainable method to appropriately utilize wastes from granite as well as glass industries in brick manufacturing. An ecofriendly and low-cost manufacturing process of ash-based bricks pertaining to the Indian standard codal provisions that can be adopted on the commercial scale is deliberated. The research also recommends the method for predicting the strength of the ash-based bricks using machine learning algorithms like random forests and decision trees. For positive synergy in the performance, both the granite tailings and glass waste must be used together. Using the granite tailings and glass waste together led to a significant reduction of 75\% in the fly ash requirement without compromising the brick's performance. The addition of the granite tailings and glass waste in the mix could increase the strength of the brick by 90.5\% and 37.7\%, respectively. Beyond 30\% dosage of granite, tailings are not recommended as they may lead to the poor gradation of particles and weak bonding in the microstructure. The glass waste in the mixture should not be more than 15\% as it causes the dilution of pozzolanic reactions thereby forming fewer hydrated compounds. Brick's durability is known after exposing the specimens for 1 year to sewers and biogenic corrosion environment, marine environment, and saline soil environment, respectively. The inclusion of the industrial wastes significantly reduced the specimen damage in the extreme environmental conditions along with the least absorption rates. The dosage of ash, granite tailings, and glass waste has to be maintained around 15\%, 30\%, and 15\%, respectively for attaining the optimum performance. Out of the generated machine learning algorithms, only random forests could be able to predict the values accurately with R-2 values at 0.90 and with comparatively lesser errors.
Cellulose nanocrystals (CNCs) have attracted great interest from researchers from academic and industrial areas because of their interesting structural features and unique physicochemical properties, such as magnificent mechanical strength, high surface area, and many hydroxyl groups for chemical modification, low density, and biodegradability. CNCs are an outstanding contender for applications in assorted fields comprehensive of, e.g., biomedical, electronic gadgets, water purifications, nanocomposites, membranes. Additionally, a persistent progression is going on in the extraction and surface modification of cellulose nanocrystals to fulfill the expanding need of producers to fabricate cellulose nanocrystals-based materials. In this review, the foundation of nanocellulose that emerged from lignocellulosic biomass and recent development in extraction/preparation of cellulose nanocrystals and different types of cellulose nanocrystal surface modification techniques are summed up. The different sorts of cellulose modification reactions that have been discussed are acetylation, oxidations, esterifications, etherifications, ion-pair formation, hydrogen bonding, silanization, nucleophilic substitution reactions, and so forth. The mechanisms of surface functionalization reactions are also introduced and considered concerning the impact on the reactions. Moreover, the primary association of cellulose and different forms of nanocellulose has likewise been examined for beginners in this field. (c) 2021 Published by Elsevier B.V.
The development of modern industry provides prosperity but leads to the wasting of biomass resources. In recent years, the transformation and utilization of these green, inexpensive, and readily available waste biomass resources have become urgent and important issues in the fields of environmental protection and chemical industry. Coupled with the dual pressures of energy shortage and environmental deterioration, countries around the world have begun to compete to develop safe, environmentally friendly, and renewable biomass energy. The development and application of biomass liquid fuels have ABSTRACT Contact information: a: Key Laborator)/ of Energy Saving Technology of Food and Pharmaceutical Storage and Processing and Transportation Equipment in Good Quality (China National Light Industry), The Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences, Beijing 100190, China; b: College of Forestry, Jiangxi Agricultural University, National Forestry and Grassland Bureau Woody Spice (East China) Engineering Technology Research Center, Nanchang 330045, China; Tianjin 300222, China; {*
Biovalorization of pulp and paper activated sludge to value-added products could be an effective alternative to traditional sludge management methods, which tend to pose serious environmental issues. Since pulp and paper activated sludge consists of microbial biomass, cellulose, hemicellulose and lignin and thus, could be subjected to different hydrolysis methods to solubilize sludge solids and release simple sugars to form value-added products by the microbial fermentation process. Hence, different sludge hydrolysis methods have been summarized in this review paper. However, hydrolysis of lignocellulosic materials generates variety of toxic compounds during hydrolysis and causes detrimental effects. Therefore, different toxic compounds and their impact on microorganisms, cellulolytic enzymes and fermentation process have been discussed in detail and recent strategies to counteract the problems of inhibitors have also been briefly explained.
Enterobacter aerogenes was metabolically engineered for acetoin production. To remove the pathway enzymes that catalyzed the formation of by-products, the three genes encoding a lactate dehydrogenase (IdhA) and two 2,3-butanediol dehydrogenases (budC, and dhaD), respectively, were deleted from the genome. The acetoin production was higher under highly aerobic conditions. However, an extracellular glucose oxidative pathway in E. aerogenes was activated under the aerobic conditions, resulting in the accumulation of 2-ketogluconate. To decrease the accumulation of this by-product, the gene encoding a glucose dehydrogenase (gcd) was also deleted. The resulting strain did not produce 2-ketogluconate but produced significant amounts of acetoin, with concentration reaching 71.7 g/L with 2.87 g/L/h productivity in fed-batch fermentation. This result demonstrated the importance of blocking the glucose oxidative pathway under highly aerobic conditions for acetoin production using E. aerogenes.
High oil prices, increasing focus on renewable carbohydrate-based feedstocks for fuels and chemicals, and the recent publication of its genome sequence, have provided continuing stimulus for studies on Zymomonas mobilis. However, despite its apparent advantages of higher yields and faster specific rates when compared to yeasts, no commercial scale fermentations currently exist which use Z. mobilis for the manufacture of fuel ethanol. This may change with the recent announcement of a Dupont/Broin partnership to develop a process for conversion of lignocellulosic residues, such as corn stover, to fuel ethanol using recombinant strains of Z. mobilis. The research leading to the construction of these strains, and their fermentation characteristics, are described in the present review. The review also addresses opportunities offered by Z. mobilis for higher value products through its metabolic engineering and use of specific high activity enzymes.
The abundance of cellulose in nature, as well as its biocompatibility and functional groups, has paved the way for the development of advanced cellulose-based technologies for water and wastewater treatment. This compre-hensive review provides a detailed overview of recent advances in cellulose-based adsorbents, focusing on surface functionalization and potential applications in water and wastewater treatment technologies. The investigation of numerous cellulose-based adsorbents has demonstrated that the introduction of surface func-tional groups such as carboxyl, succinate, amine, imidazole, amidoxime, thiol, thioether, sulfonate, dithiocar-bamate, xanthate, phosphate, and so on through chemical modification techniques significantly improves their adsorption properties and selectivity towards metallic species. The review delves into the use of cellulose-based adsorbents for the removal of potentially toxic elements, radionuclides, and the recovery of precious metals from water and wastewater. Furthermore, the potential of blended adsorbents that incorporate various types of cel-lulose in the form of composites, nanocomposites, and hybrids is highlighted. Furthermore, this review assesses cellulosic biomaterials with varying cellulose contents to determine their potential as metal sorbents. Finally, current research trends, gaps, challenges, and future perspectives in this field are brought to the forefront.
Fast pyrolysis, which is comparable with the enzyme or acid hydrolysis, should be considered for further development for fermentable levoglucosan (LG) production. This manuscript offers a broad review of the current status and future research perspectives of LG and its hydrolysates production from lignocellulosic biomass by fast pyrolysis for fermentation. The utilization, distribution and formation paths of LG from cellulose are presented. In consideration of the complexity of cellulose structure and lignocellulosic components, the influence of the major individual components (cellulose, hemicellulose, lignin and ash) and the structural properties (particle size, degree of polymerization and crystallinity) on the LG formation are reviewed. Aiming to further improve the yield of LG and the fermentability of pyrolysate, a number of pretreatment methods (e.g. hot-water pretreatment, acid pretreatment, acid impregnation) prior to fast pyrolysis, hydrolysis of LG and detoxification before fermentation, and microbial production of valuable products are also discussed in detail. At last, a brief conclusion for the challenge in this topic is provided. The low content of LG and the presentence of inhibitors to biocatalysts in the pyrolysate of lignocelluloses hamper the fermentable utilization of pyrolytic sugars, which need further investigation and improvement to make this process feasible.
Long chain alcohol have the potential to become an alternative of fuel ethanol, due to their outstanding combustion properties. Succinic acid is an important platform compound of wide applications. Biofuel and chemicals produced with lignocellusic materials is a promising option for biorefinery development. During the production of long chain alcohol by microorganisms, large amount of CO2 will be generated, while CO2 can be used as raw material for succinic acid fermentation. To introduce the knowledge about the implications of co-production process, a review on the utilization of lignocellulosic biomass for long chain alcohol and succinic acid production and CO2 mitigation are presented.
It is hypothesized that rapeseed lecithins may have different emulsifying and antioxidant properties in delivering fish oil compared to soy lecithin based on previous studies. The results showed that in vitro antioxidant activities of rapeseed lecithins were stronger than those of soy lecithin. Emulsions stabilized by rapeseed based lecithins and DATEM were stable over 3 months at 4 degrees C, whereas the creaming of emulsions containing soy lecithin started immediately after its preparation. Zeta-potential of rapeseed lecithins was higher than soy lecithin and DATEM, which partially contributed to the emulsion stability. Although the particle sizes of emulsions prepared by rapeseed lecithins increased after 14 days storage, no creaming was observed. Lipid oxidation as indicated by TBARS values suggested that DATEM was the most unfavorable, followed by soy lecithin. It is concluded that rapeseed lecithins are better than soy lecithin and DATEM in terms of emulsion stability and antioxidant capability, respectively.
Radionuclide-contaminated water is carcinogenic and poses numerous severe health risks and environmental dangers. The activated carbon (AC)-based adsorption technique has great potential for treating radionuclide-contaminated water due to its simple design, high efficiency, wide pH range, quickness, low cost and environmental friendliness. This critical review first provides a brief overview of the concerned radionuclides with their associated health hazards as well as different removal techniques and their efficacy of removing them. Following this overview, this study summarizes the surface characteristics and adsorption capabilities of AC derived from different biomass precursors. It compares the adsorption performance of AC to other adsorbents, such as zeolite, graphene, carbon nano-tubes and metal-organic frameworks. Furthermore, this study highlights the different factors that influence the physical characteristics of AC and adsorption capacity, including contact time, solution pH, initial concentration of radionuclides, the initial dosage of the adsorbent, and adsorption temperature. The theoretical models of adsorption isotherm and kinetics, along with their fitting parameter values for AC/radionuclide pairs, are also reviewed. Finally, the modification procedures of pristine AC, factors determining AC characteristics and the impact of modifying agents on the adsorption ability of AC are elucidated in this study; therefore, further research and development can be promoted for designing a highly efficient and practical adsorption-based radionuclide removal system.
The non-conventional yeast Kluyveromyces marxianus is widely used for several biotechnological applications, mainly due to its thermotolerance, high growth rate, and ability to metabolise a wide range of sugars. These cell traits are strategic for lignocellulosic biomass valorisation and strain diversity prompts the development of robust chassis, either with improved tolerance to lignocellulosic inhibitors or ethanol. This review summarises bioethanol and value-added chemicals production by K. marxianus from different lignocellulosic biomasses. Moreover, metabolic engineering and process optimization strategies developed to expand K. marxianus potential are also compiled, as well as studies reporting cell mechanisms to cope with lignocellulosic-derived inhibitors. The main lignocellulosic-based products are bioethanol, representing 71\% of the reports, and xylitol, representing 17\% of the reports. K. marxianus also proved to be a good chassis for lactic acid and volatile compounds production from lignocellulosic biomass, although the literature on this matter is still scarce. The increasing advances in genome editing tools and process optimization strategies will widen the K. marxianus-based portfolio products.
Plastic wastes have posed serious threats to the environment, including decrease of soil nutrient effectiveness and agricultural production as well as emerge of ecological instability. Fuel conversion from plastic waste is regarded as a promising strategy for its disposal and energy utilization. Plastic wastes can be converted into target fuels by adjusting cracking of chemical bonds. Currently, numerous technologies regarding fuel conversion from plastic wastes have been reported, including conventional pyrolysis, novel heat treatment and advanced oxidation. However, systematic summary and comparative analysis of different technologies are still scarcely reported. In this review, fuel conversion from plastic wastes was summarized comprehensively, highlighting novel heat treatment and advanced oxidation technologies reported in recent years. Furthermore, the superiority and drawbacks of each technology were analyzed, and future prospects of technology application were proposed. With lower reaction temperature and higher-value fuel, novel heat treatment of plastics is more popular than traditional one. Advanced oxidation can be controlled to convert plastics into fuels under room temperature and pressure, guiding the new normal in energy utilization of plastic wastes. This review aims to provide inspiration for energy utilization of solid waste, addressing the issues of white pollution and energy shortage.
Biohydrogen production via dark fermentation using fermentable sugars from biomass materials is a sustainable way of procuring biohydrogen. Lignocellulosic biomass is a potential renewable feedstock for dark fermentation, but its use is challenged by the recalcitrant nature and generation of certain fermentation inhibitors resulting in compromised fermentation performance. Consolidated bioprocessing (CBP), the successful integration of hydrolysis and fermentation of lignocellulosic biomass to desirable products, has received tremendous research attentions in recent years to boost renewable fuel production in an economically feasible way. A microbial strain capable of both biomass hydrolysis and hydrogen fermentation is critical for successful CBP-based hydrogen fermentation. This review provides comprehensive information on dark fermentation for hydrogen production using lignocellulosic biomass as a potential feedstock with a CBP approach. Consolidated bioprocessing of lignocellulosic biomass for biohydrogen production via native and recombinant microbial strains is discussed in detail. Potential bottlenecks in the above mentioned processes are critically analyzed and future research perspectives are presented. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Biofuels and biomaterials are gaining increased attention because of their ecofriendly nature and renewable precursors. Biochar is a recalcitrant carbonaceous product obtained from pyrolysis of biomass and other biogenic wastes. Biochar has found many notable applications in diverse areas because of its versatile physicochemical properties. Some of the promising biochar applications discussed in this paper include char gasification and combustion for energy production, soil remediation, carbon sequestration, catalysis, as well as development of activated carbon and specialty materials with biomedical and industrial uses. The pyrolysis temperature and heating rates are the limiting factors that determine the biochar properties such as fixed carbon, volatile matter, mineral phases, surface area, porosity and pore size distribution, alkalinity, electrical conductivity, cation-exchange capacity, etc. A broad investigation of these properties determining biochar application is rare in literature. With this objective, this paper comprehensively reviews the evolution of biochar from several lignocellulosic biomasses influenced by pyrolysis temperature and heating rate. Lower pyrolysis temperatures produce biochar with higher yields, and greater levels of volatiles, electrical conductivity and cation-exchange capacity. Conversely, higher temperatures generate biochar with a greater extent of aromatic carbon, alkalinity and surface area with microporosity. Nevertheless, this coherent review summarizes the valorization potentials of biochar for various environmental, industrial and biomedical applications. {[
Bio-oil was produced at 450 degrees C by fast pyrolysis in a continuous auger reactor. Four feed stocks were used: pine wood, pine bark, oak wood, and oak bark. After extensive characterization of the whole bio-oils and their pyrolytic lignin-rich ethyl acetate fractions by gas chromatography/mass spectrometry (GC/MS), gel permeation chromatography (GPC), calorific values, viscosity dependences on shear rates and temperatures, elemental analyses, H-1 and C-13 NMR spectroscopy, water analyses, and ash content, these bio-oils were shown to be comparable to bio-oils produced by fast pyrolysis in fluidized bed and vacuum pyrolysis processes. This finding suggests that portable auger reactors might be used to produce bio-oil at locations in forests to generate bio-oil on-site for transport of the less bulky bio-oil (versus raw biomass) to biorefineries or power generation units. The pyrolysis reported herein had lower heat transfer rates than those achieved in fluidized bed reactors, suggesting significant further improvements are possible.
Nanocellulose has received immense consideration owing to its valuable inherent traits and impressive physicochemical properties such as biocompatibility, thermal stability, non-toxicity, and tunable surface chemistry. These features have inspired researchers to deploy nanocellulose as nanoscale reinforcement materials for biobased polymers. A simple yet efficient characterization method is often required to gain insights into the effectiveness of various types of nanocellulose. Despite a decade of continuous research and booming growth in scientific publications, nanocellulose research lacks a measuring tool that can characterize its features with acceptable speed and reliability. Implementing reliable characterization techniques is critical to monitor the specifications of nanocellulose alone or in the final product. Many techniques have been developed aiming to measure the nano-reinforcement mechanisms of nanocellulose in polymer composites. This review gives a full account of the scientific underpinnings of techniques that can characterize the shape and arrangement of nanocellulose. This review aims to deliver consolidated details on the properties and characteristics of nanocellulose in biopolymer composite materials to improve various structural, mechanical, barrier and thermal properties. We also present a comprehensive description of the safety features of nanocellulose before and after being loaded within biopolymeric matrices.
Product inhibition of beta-glucosidases is one of the principal factors limiting the efficiency of enzymatic lignocellulosic biomass hydrolysis, particularly at high-solids concentrations. The availability of beta-glucosidases with high catalytic efficiency for cellobiose hydrolysis at relatively low temperatures is of major importance for the development of efficient and cost-effective simultaneous saccharification and fermentation (SSF) processes. The gene encoding the beta-glucosidase from Neurospora crassa (gh1-1) was cloned and expressed in soluble form in Escherichia coli. The recombinant enzyme (GH1-1) was monomeric (54.2 kDa) and showed optimal temperature and pH of 40-45 degrees C and 5.5-6.5, respectively. Moreover, activities around 70\% of the maximal were maintained at pH 5.0 and 35 degrees C. The enzyme was highly stable at pH 5.5-8.0 and 35 degrees C, and showed a half-life of 70min at 40 degrees C in water. GH1-1 showed similar apparent affinities for cellobiose (0.21 +/- 0.01 mmol L-1) and p-nitrophenyl-beta-D-glucopyranoside (pNP-Glc) (0.28 +/- 0.01 mmol L-1) but hydrolyzed cellobiose with 3.2-fold higher maximal velocity (52.0 +/- 3.1 U mg(-1)) and 4.3-fold higher catalytic efficiency (223.8 L mmol(-1) s(-1)). Hydrolysis of pNP-Glc by GH1-1 was maximally stimulated 1.8 and 2.0-fold by glucose and xylose at 100 and 150 mmol L-1 concentration, respectively. Moreover, the enzyme was tolerant to glucose up to 950 mmol L-1 and xylose up to 910 mmol L-1. Xylose (60-80 mmol L-1) also stimulated the cellobiase activity of GH1-1 about 3.6-fold. Altogether, the characteristics of GH1-1 reveal its excellent potential for application as a component of enzymatic cocktails for the hydrolysis of lignocellulosic biomass, both in separate hydrolysis and fermentation and SSF processes. (C) 2015 Elsevier B.V. All rights reserved.
The insights of nanotechnology for cellulosic biohydrogen production through dark fermentation are reviewed. Lignocellulosic biomass to sugar generation is a complex process and covers the most expensive part of cellulose to sugar production technology. In this context, the impacts of nanomaterial on lignocellulosic biomass to biohydrogen production process have been reviewed. In addition, the feasibility of nanomaterials for implementation in each step of the cellulosic biohydrogen production is discussed for economic viability of the process. Numerous aspects such as possible replacement of chemical pretreatment method using nanostructured materials, use of immobilized enzyme for a fast rate of reaction and its reusability along with long viability of microbial cells and hydrogenase enzyme for improving the productivity are the highlights of this review. It is found that various types of nanostructured materials e.g. metallic nanoparticles (Fe degrees, Ni, Cu, Au, Pd, Au), metal oxide nanoparticles (Fe2O3, F3O4, NiCo2O4, CuO, NiO, CoO, ZnO), nanocomposites (Si@CoFe2O4, Fe3O4/alginate) and graphene-based nanomaterials can influence different parameters of the process and therefore may perhaps be utilized for cellulosic biohydrogen production. The emphasis has been given on the cost issue and synthesis sustainability of nanomaterials for making the biohydrogen technology cost effective. Finally, recent advancements and feasibility of nanomaterials as the potential solution for improved cellulose conversion to the biohydrogen production process have been discussed, and this is likely to assist in developing an efficient, economical and sustainable biohydrogen production technology.
The impact of ionic liquids (ILs) namely 1-butyl-3-methylimidazolium chloride ({[
The large quantities of the petroleum-based foam materials used have raised concern due to their negative effects on the environment, predominantly single-use articles in packaging applications. Thus, considerable efforts have been put forth to develop environmentally friendly alternatives and, in particular, starch foams. Many techniques including extrusion, hot-mold baking/compression, microwave heating, freeze-drying/solvent exchange, and supercritical fluid extrusion can be used to produce starch foams with different cellular structures and properties. Starch by itself is, however, rather weak and water sensitive. To improve microstructure, mechanical and thermal properties, moldability, water resistance, lightness and other properties of starch-based foams, many approaches, e.g., chemical modification of starches, blending with various biodegradable polymers, incorporation of natural fibers, and addition of nanofillers, have been attempted and are intensively reviewed in this article. (C) 2015 Elsevier Ltd. All rights reserved.
Strong interfacial interaction between bamboo cellulose fiber (BCF) and a polymeric matrix is very important to improve the mechanical properties of cellulose fiber-reinforced polymeric composites. In this study, we developed an effective approach to enhance the interfacial adhesion through modifying both polypropylene (PP) and cellulose fiber. Maleic anhydride was mechanochemically grafted onto PP to achieve the interaction with the reactive hydroxyl groups on the surface of 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-oxidized bamboo cellulose fiber (TBCF). Fourier transform infrared spectra and X-ray diffraction analysis indicated the existence of strong interfacial interaction between TBCF and the modified PP matrix. It was further found by thermogravimetric analysis that about 5 wt\% of PP formed a strong combining force with TBCF after melt compounding. The combination of mechanochemical modification of PP and TEMPO-mediated oxidation of BCF showed a synergistic effect on the tensile strength of the prepared composites. The tensile strength of modified PP/TBCF (50/50 wt\%) composites prepared through dual modification was remarkably improved compared to those of neat PP/TBCF composites and modified PP/BCF composites, enhanced by about 112.4\% and 53.8\%, respectively.
In new biorefinery processes, NMMO/water is used for the pre-treatment of biomass to increase the efficiency of subsequent digestion processes, while GVL/water is used for ``organosolv{''
Lignocellulosic biomass is the most abundant renewable source of bioenergy. However, its intertwined structures prevent the embedded cellulose and hemicellulose from undergoing further chemical transformations. Organosolv pretreatment has been known to be effective in reducing the recalcitrance of lignocellulosic biomass. It possesses advantages in the recovery of components and the recovered components such as cellulose can be converted into bioproducts through consolidated bioprocessing (CBP). The main objective of this paper is to review recent developments in organosolv pretreatment, including a comparison of different organic solvents and their optimum operation conditions in terms of pretreatment performance and efficiency. Conventional solvents were also compared with several emerging solvents to discover more potential utilization of organosolv pretreatment. This paper also reviewed fundamental knowledge regarding organosolv pretreatment such as its mechanism, and the chemical and physical properties of the solvents, which are still rarely discussed in the literature due to a lack of conclusive information. The challenges and way forward for organosolv pretreatment were also analyzed in depth to consider the synergistic advantages after the integration of organosolv pretreatment into CBP. It is believed that, through more fundamental exploration and optimization work, organosolv pretreatment can play a vital role in determining the sustainability of CBP, to pave the way for more efficient bioprocessing in the future. (c) 2020 Society of Chemical Industry and John Wiley \& Sons, Ltd
Succinic acid (SA) is used as a commodity chemical and as a precursor in chemical industry to produce other derivatives such as 1,4-butaneidol, tetrahydrofuran, fumaric acid, and bio-polyesters. The production of bio-based SA from renewable feedstocks has always been in the limelight owing to the advantages of renewability, abundance and reducing climate change by CO2 capture. Considering this, the current review focuses on various 2G feedstocks such as lignocellulosic biomass, crude glycerol, and food waste for cost-effective SA production. It also highlights the importance of producing SA via separate enzymatic hydrolysis and fermentation, simultaneous saccharification and fermentation, and consolidated bioprocessing. Furthermore, recent advances in genetic engineering, and downstream SA processing are thoroughly discussed. It also elaborates on the techno-economic analysis and life cycle assessment (LCA) studies carried out to understand the economics and environmental effects of bio-based SA synthesis.
The interest of researchers has been more and more focused on identifying adsorption materials for pollutant removal with a specific interest in agriculture waste. It is noteworthy that many agricultural wastes are modified in different ways to improve the porosity and surface area of the material. Activation, carbonisation and grafting are only some of the most utilised technologies to produce adsorbents from agricultural waste. Some agriculture waste filters use less adsorbent and achieve the same metal ion adsorption efficiency of commercial filters at a potentially cheaper price. As they are made from renewable material found in abundance, they provide a solution to environmental problems and offer an additional value to the agricultural economy. This paper presents an overview of the recent improvements in the field and represents an evaluation of the different possibilities of using agricultural by-products to produce activated carbon for water purification.
Torrefaction is a developing thermal process that has mainly been used to convert lignocellulosic feedstocks, both cultured and wasted, into a ``charred{''
Background: Butyric acid is an important chemical currently produced from petrochemical feedstocks. Its production from renewable, low-cost biomass in fermentation has attracted large attention in recent years. In this study, the feasibility of corn husk, an abundant agricultural residue, for butyric acid production by using Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor (FBB) was evaluated. Results: Hydrolysis of corn husk (10\% solid loading) with 0.4 MH2SO4 at 110 degrees C for 6 h resulted in a hydrolysate containing similar to 50 g/L total reducing sugars (glucose:xylose = 1.3:1.0). The hydrolysate was used for butyric acid fermentation by C. tyrobutyricum in a FBB, which gave 42.6 and 53.0\% higher butyric acid production from glucose and xylose, respectively, compared to free-cell fermentations. Fermentation with glucose and xylose mixture (1:1) produced 50.37 +/- 0.04 g L-1 butyric acid with a yield of 0.38 +/- 0.02 g g(-1) and productivity of 0.34 +/- 0.03 g L-1 h(-1). Batch fermentation with corn husk hydrolysate produced 21.80 g L-1 butyric acid with a yield of 0.39 g g(-1), comparable to those from glucose. Repeated-batch fermentations consistently produced 20.75 +/- 0.65 g L-1 butyric acid with an average yield of 0.39 +/- 0.02 g g(-1) in three consecutive batches. An extractive fermentation process can be used to produce, separate, and concentrate butyric acid to > 30\% (w/v) sodium butyrate at an economically attractive cost for application as an animal feed supplement. Conclusion: A high concentration of total reducing sugars at similar to 50\% (w/w) yield was obtained from corn husk after acid hydrolysis. Stable butyric acid production from corn husk hydrolysate was achieved in repeated-batch fermentation with C. tyrobutyricum immobilized in a FBB, demonstrating that corn husk can be used as an economical substrate for butyric acid production.
Biofuel has emerged as an alternative source of energy to reduce the emissions of greenhouse gases in the atmosphere and combat global warming. Biofuels are classified into first, second, third and fourth generations. Each of the biofuel generations aims to meet the global energy demand while minimizing environmental impacts. Sustainability is defined as meeting the needs of the current generations without jeopardizing the needs of future generations. The aim of sustainability is to ensure continuous growth of the economy while protecting the environment and societal needs. Thus, this paper aims to evaluate the sustainability of these four generations of biofuels. The objectives are to compare the production of biofuel, the net greenhouse gases emissions, and energy efficiency. This study is important in providing information for the policymakers and researchers in the decision-making for the future development of green energy. Each of the biofuel generations shows different benefits and drawbacks. From this study, we conclude that the first generation biofuel has the highest biofuel production and energy efficiency, but is less effective in meeting the goal of reducing the greenhouse gases emission. The third generation biofuel shows the lowest net greenhouse gases emissions, allowing the reduction of greenhouse gases in the atmosphere. However, the energy required for the processing of the third generation biofuel is higher and, this makes it less environmentally friendly as fossil fuels are used to generate electricity. The third and fourth generation feedstocks are the potential sustainable source for the future production of biofuel. However, more studies need to be done to find an alternative low cost for biofuel production while increasing energy efficiency.
The present work aims at employment of cucumber peel for adsorption of cadmium in packed-bed column reactor in an attempt to testify the efficiency of this sorbent for treating huge volume of wastewater needed for practical purpose. The study was performed with dried and powdered cucumber peel packed in a glass column reactor with influent metal solution being pumped in upflow mode using peristaltic pump at pH 5.0. Different design parameters of adsorption in continuous mode were evaluated, and experiments were performed at varied flow rates (15, 18 and 20mLmin(-1)), bed heights (5.0, 6.5 and 8.0cm) and influent concentrations (50 and 100mg L-1). Results illustrated delayed breakthrough, and higher percentage removal of cadmium wereassociated with lowest flow rate, highest bed height and lower influent concentration. Experimental outcome further revealed percentage removal of 78.03\% at saturation with adsorption capacity of 107.76mgg(-1) at 50mgL(-1) influent concentration, 20mLmin(-1) flow rate and 8.0cm bed height. Evaluation of experimental data with different kinetic models established pertinence of Thomas model and Yoon-Nelson model in defining adsorption pattern in continuous mode. Elution of adsorbed cadmium from packed bed was executed using 0.1M HCl which efficiently recovered more than 94\% of the loaded metal in three consecutive cycles. The work has conveniently established the prospect of cucumber peel as a cheap biological sorbent for treating large volume of cadmium contaminated water.
Cellulosic ethanol production relies on the biochemical (enzymatic) conversion of lignocellulose to fermentable sugars and ultimately to bioethanol. However, the cost of lignocellulolytic enzymes is a limiting factor in the commercialisation of this technology. This therefore necessitates the optimisation of lignocellulolytic enzyme cocktails through the elucidation of synergistic interactions between enzymes so as to improve lignocellulose hydrolysis and also lower protein loadings in these reactions. However, many factors affect the synergism that occurs between these lignocellulolytic enzymes, such as enzyme ratios, substrate characteristics, substrate loadings, enzyme loadings and time. This review examines the effect of time on the synergistic dynamics between lignocellulolytic enzymes during the hydrolysis of both complex (true) lignocellulosic substrates and model substrates. The effect of sequential and simultaneous application of the lignocellulolytic enzymes on the synergistic dynamics during the hydrolysis of these substrates is also explored in this review. Finally, approaches are further proposed for efficient and synergistic hydrolysis of both complex lignocellulosic substrates and model substrates. With respect to the synergistic enzymatic hydrolysis of lignocellulosic biomass, this review exposed knowledge gaps that should be covered in future work in order to fully understand how enzyme synergism works: e.g. elucidating protein to protein interactions that exist between these enzymes in establishing synergy; and the effect of lignocellulose degradation products of one enzyme on the behaviour of the other enzyme and ultimately their synergistic relationship.
Availability of biomass makes biofuel from bioresources more feasible. Recently, algal biomass (AB) and lignocellulosic biomass (LB) have been widely used in bioelectrochemical systems (BESs) for bioelectricity and biohydrogen production. However, no review provides the current scenario of bioelectricity and biohydrogen generation from various biomass and biowaste in BESs. Therefore, the current review provides a recent and indepth understanding of biomass-specific BESs including biomass selection, pretreatment approaches, dominating microbes, economic feasibility, and pilot-scale up. Biomass of E. prolifera and bamboo (hydrolysate) were reported to have a high ability for bioelectricity generation with maximum power densities of 3810 and 578 mW m(-2), respectively. Biohydrogen productions were 1608 and 1017 mL H-2 g(-1) with fruit waste and S. Japonica, respectively. Previous studies used single biomass in BESs and almost there is no research work on mixed biomass. Co-digestion and/or mixing of biomass (such as AB and LB) or biowaste (lipid-rich and carbohydrate-rich feedstock) would enhance the accessibility of substrates to microbes which could increase the bioelectricity and biohydrogen. The integration of MFCs with primary and secondary units of wastewater treatment plants (WWTPs) is restricted to the utilization of wastewater and sludge (i.e., substrate). Thus, biomass augmentation as an external substrate in WWTP might facilitate the growth of electroactive microbes and can efficiently support the pilot-scale BESs.
Extraction of bioactive molecules has become a major trend in the valorization of food and agroindustrial byproducts, allowing a sustainable production of novel ingredients with different industrial applications. Enzymatic and enzyme-assisted extraction eco-friendly methods could be used to extract value-added compounds from lignocellulosic plant byproducts with interesting biological properties, namely, polysaccharides and polyphenols. Nevertheless, a deep understanding of their enzymatic hydrolytic properties as well as the interactions with the plant cell material is necessary to obtain better extracts with high yields. Therefore, this review focuses on enzymatic treatment of food lignocellulosic byproducts in order to recover bioactive compounds such as polysaccharides and polyphenols.
A review of the pharmacological applications of lignins provides evidence of their protective role against the development of different diseases. In many cases, the effects of lignins could be explained by their antioxidant capacity. Here, we present a systematic review of the literature from the period 2010-2016 which provides information concerning new applications of lignins derived from recent research. The most promising findings are reported, including the methodologies employed and results obtained with lignins or their derivatives which may improve human health. We highlight potential applications in the treatment of obesity, diabetes, thrombosis, viral infections and cancer. Moreover, we report both that lignins can be used in the preparation of nanoparticles to deliver different drugs and also their use in photoprotection.
Functionalization of microcrystalline cellulose (MCC) with EDTA dianhydride (EDTAD) was first achieved using an esterification reaction. N-Hydroxysuccinimide-activated MCC-EDTAD ester (MEN), a novel macromolecule crosslinker based on MCC, was synthesized for the modification of gelatin films. The reaction between gelatin and MEN was verified by the residual free amino test, FTIR and XRD spectra. The introduction of MEN into gelatin decreased the film degradation ratio and increased its thermal stability, flexibility, hydrophobicity, light barrier performance and water uptake ability. Additionally, SEM images proved the successful surface grafting reaction and degradation phenomenon. This unique gelatin film material with advanced properties broke the limitation of the blending method for modification of gelatin with macromolecules and broadened its application as a novel sustained-release material.
Brewery wastewater (BWW) is an appealing low-cost substrate for the production of single cell oils by oleaginous microorganisms. However, it may contain inhibitor compounds that may affect the microbial metabolism. This work investigated, for the first time, the presence of potential inhibitor compounds in primary brewery wastewater (PBWW) and secondary brewery wastewater (SBWW) for the pure and mixed cultivation of the yeast Rhodosporidium toruloides NCYC 921 and the microalga Tetradesmus obliquus ACOI 204/07. Three organic acids (OrgAc) were identified in the brewery effluents (acetic, propionic and butyric acids). Yeast and microalga pure and mixed cultivations were performed in PBWW and SBWW in order to understand the behaviour of the microorganisms, individually and together. Flow cytometry (FC) was used to monitor each microbial population during the mixed cultivations, and to study the yeast and microalga cell viability throughout all cultivations. The yeast cells in pure cultures grown in both effluents were severely affected by the OrgAc presence confirmed by the cell stress results obtained by FC. However, in the mixed cultures, the yeast cells were able to develop, and the levels of stress conditions were considerably lower. Only in microalga pure and mixed cultures efficient OrgAc removal was observed.
Lignocellulosic biomasses (LCB) are sustainable and abundantly available feedstocks for the production of biofuel and biochemicals via suitable bioconversion processing. The main aim of this review is to focus on strategies needed for the progression of viable lignocellulosic biomass-based biorefineries (integrated approaches) to generate biofuels and biochemicals. Processing biomass in a sustainable manner is a major challenge that demands the accomplishment of basic requirements relating to cost effectiveness and environmental sustainability. The challenges associated with biomass availability and the bioconversion process have been explained in detail in this review. Limitations associated with biomass structural composition can obstruct the feasibility of biofuel production, especially in mono-process approaches. In such cases, biorefinery approaches and integrated systems certainly lead to improved biofuel conversion. This review paper provides a summary of mono and integrated approaches, their limitations and advantages in LCB bioconversion to biofuel and biochemicals.
The need to pre-treat lignocellulosic biomass prior to dark fermentation results primarily from the composition of lignocellulose because lignin hinders the processing of hard wood towards useful products. Hence, in this work a two-step approach for the pre-treatment of energy poplar, including alkaline pre-treatment and enzymatic saccharification followed by fermentation has been studied. Monoethanolamine (MEA) was used as the alkaline catalyst and diatomite immobilized bed enzymes were used during saccharification. The response surface methodology (RSM) method was used to determine the optimal alkaline pre-treatment conditions resulting in the highest values of both total released sugars (TRS) yield and degree of lignin removal. Three variable parameters (temperature, MEA concentration, time) were selected to optimize the alkaline pre-treatment conditions. The research was carried out using the Box-Behnken design. Additionally, the possibility of the re-use of both alkaline as well as enzymatic reagents was investigated. Obtained hydrolysates were subjected to dark fermentation in batch reactors performed by Enterobacter aerogenes ATCC 13048 with a final result of 22.99 mL H-2/g energy poplar (0.6 mol H-2/mol TRS).
In this study, the physicochemical properties, the thermal degradation behavior and the products generated from pyrolysis of brewer's spent grain (BSG) were investigated to evaluate the potential of this agro-industrial residue for bio-oil production via pyrolysis. Thermogravimetric analyses were performed in a nitrogen atmosphere. The kinetic parameters were estimated by isoconversional methods and by independent parallel reactions model (IPR). The results showed that the BSG has a good potential for bio-oil production owing to its high volatile matter content and the high heating value. The kinetic behavior was successfully modeled by the IPR model. High added-value compounds were identified from analytical pyrolysis, which indicates that BSG can be a source of important raw materials for the chemical industry.
Catalytic hydrogenation of biomass feedstocks into clean fuels and chemicals by heterogeneous catalysis is one of the most important means to realize the utilization of biomass, which has a promising appli-cation prospect. This review summarizes the recent advances in the preparation of metal/biochar cata-lysts and the commonness and individuality of catalytic performance for hydrogenation of biomass via noble metal-based catalyst, non-noble metal-based catalyst and bimetallic catalyst, followed by a dis-cussion of the catalytic mechanism and performance of biomass hydro-upgrading process. Specially, this work details the advantages of biochar as support (such as rich oxygen-containing functional groups, rich pore structure, long catalytic life, etc.), the specific catalytic mode of each active site on the metal/biochar catalyst during the hydro-upgrading process, and the interaction mode between the biochar and the metal. Furthermore, more attention is proposed to the fine control of the structure of the metal/biochar catalysts. (c) 2021 Elsevier Ltd. All rights reserved.
Two types of granular adsorbents-supported zero-valent iron (ZVI) were prepared and applied to remove crystal violet (CV). One type of ZVI was synthesized by the chemical reduction method and deposited on the surface of granular porous adsorbent (Fe@GAC). The other type of ZVI was synthesized by direct reduction of iron ore tailing powder with the coke in high temperature reducing atmosphere and was embedded in granular porous adsorbent (Fe@GAR). Fe@GAC and Fe@GAR were characterized by SEM, EDX, XRD, FTIR, and BET. The effect of parameters like contact time, initial CV concentration, pH values, and temperature on the removal of CV was investigated. According to the results, the Langmuir model was in good agreement with the experimental data, where the maximum removal capacity of Fe@GAC and Fe@GAR was found to be 95.24 mg/g and 123.45 mg/g at 293 K, respectively. The kinetic studies indicated that the pseudo-second-order kinetic model agreed well with the experimental data. Thermodynamic parameters were calculated and analyzed, which suggested that the removal processes were spontaneous and endothermic. The mechanism of CV removal by Fe@GAC and Fe@GAR included adsorption and simultaneous chemical reduction. Compared with Fe@GAC, Fe@GAR owned more amount of ZVI, larger specific surface area and higher removal capacity, which made it a more promising adsorbent in wastewater treatment.
This paper investigated the utilization of calcined-red mud (CRM) pretreatment to enhance fermentative hydrogen yields from brewers' spent grain (BSG). The BSG samples were treated with different concentrations (0.0-20 g/L) of CRM at 55 degrees C for 48 h, before the biohydrogen process with heat-treated anaerobic sludge inoculum. The highest specific hydrogen production of 198.62 ml/g-VS was obtained from the BSG treated with 10 g/L CRM, with the corresponding lag time of 10.60 h. Hydrogen yield increments increased by 67.74\%, compared to the control tests without CRM. The results demonstrated that the CRM could hydrolyze more cellulose and further provided adequate broth and suitable pH value for efficient fermentative hydrogen. The model-based analysis showed that the modified Gompertz model presented a better fit for the experimental data than the first-order model. (C) 2016 Elsevier Ltd. All rights reserved.
For decades, lignocellulosic biomass has been introduced to the public as the most important raw material for the environmentally and economically sustainable production of high-valued bioproducts by microorganisms. However, due to the strong recalcitrant structure, the lignocellulosic materials have major limitations to obtain fermentable sugars for transformation into value-added products, e.g., bioethanol, biobutanol, biohydrogen, etc. In this review, we analyzed the recent trends in bioenergy production from pretreated lignocellulose, with special attention to the new strategies for overcoming pretreatment barriers. In addition, persistent challenges in developing for low-cost advanced processing technologies are also pointed out, illustrating new approaches to addressing the global energy crisis and climate change caused by the use of fossil fuels. The insights given in this study will enable a better understanding of current processes and facilitate further development on lignocellulosic bioenergy production.
Energy plants have several advantages, such as, low lignin, fast growth, large production and perenniality, and present great potential for biofuel production. To enhance its biodegradability, in this study, carbide slag as a novel pretreatment agent was employed to pretreat four typical energy plants, namely Medicago saliva, Panicum virgatwn, Triarrhena lutarioriparia, and Arundo donax. These energy plants were all pretreated in 1.75\% (w/v) carbide slag solution at 120 degrees C for 1 h, and then were hydrolyzed to produce reducing sugar within 72 h by an enzymes loading of 30 FPU/g substrate. The results showed that thermo-carbide slag remarkably disrupted the surface microstructure from a high compact and tight structure to a poly-ravine and distorted structure of four energy plants. Thermo-carbide slag pretreatment significantly facilitated the removal of hemicellulose and lignin, and increased the crystallinity indexes. After thermo-carbide slag pretreatment, four energy plants yielded more than 220 mg/g of reducing sugar. The maximum reducing sugar yield of 297.87 mg/g was produced from pretreated Panic-tan virgatwn, which is 7.9 times higher compared with that of raw Panicum virgatwn. The significant improvement of enzymatic hydrolysis may be attributed to the low lignin content, higher retention of cellulose, and low crystallinity after the thermo-carbide slag pretreatment. Thermo-carbide slag pretreatment is a promising pretreatment method, especially for Panicum virgatum. Carbide slag, as the abundant and cheap alkaline waste, can reduce the processing cost of energy plant bioconversion for further biofuel production. The study provides a novel research direction for further biofuel production through waste treating waste.
Xylitol is a pentahydroxy sugar alcohol coming from xylose with many applications in the food and pharmaceutical industries as a low caloric sweetener suitable for diabetics and as an active ingredient in several biomedical applications. The microbial bioproduction of xylitol from natural xylose coming from lignocellulosic materials appears a sustainable and a promising alternative to chemical synthesis, which works at stronger reaction conditions and generates undesirable co-products which must be removed. There are several reviews that study the metabolic pathways in wild and transformed xylitol producing yeasts and the culture conditions that enhance xylitol accumulation, which are mainly related to the need of microaerobiose for the best producing wild yeasts. Nevertheless, there are relatively few studies focusing on the engineering aspects related to scalable systems and bioreactors that could result in a final industrial stage. This review explores recent advances on xylitol production using immobilized systems, which have been proposed to facilitate the reuse of the biocatalyst for extended periods and the main types of bioreactors available assayed for this purpose.
The constant environmental and social pressure on the search for alternative and clean technologies has strongly influenced the construction industry, which is considered as one of the main contributors to global warming due to the emission of carbon dioxide (CO2). The objective of this study was to evaluate the effect of partial replacement of cement by activated coal waste on cement-based composites reinforced by unbleached pine pulps. The results showed that the hornification treatment reduces the water absorption capacity and increases the dimensional stability of the cellulosic pulp. In addition, the thermal treatment preserves the original chemical composition of the vegetable pulp. Moreover, the partial replacement of cement by activated coal waste (ACW) increased the mechanical performance. The results of thermogravimetric analysis showed that composites with ACW present a decrease of the calcium hydroxide content compared to composites containing limestone. After accelerated aging tests, a decrease in the reinforcement capacity of the fiber and densification of the material is observed. However, composites with treated pulps and activated coal waste showed higher mechanical prop-erties and a greater durability. According to the results, the combination of the hornification treatment and the partial replacement of cement by ACW can be used to improve the eco-efficiency of the fiber cement industry. The combination of both approaches allows to a reduction the carbon dioxide emissions (reduction of cement consumption) and an increase of the durability of the material.
The hydrodynamic cavitation comes out as a promising route to lignocellulosic biomass pretreatment releasing huge amounts of energy and inducing physical and chemical transformations, which favor lignin-carbohydrate matrix disruption. The hydrodynamic cavitation process combined with other pretreatment processes has shown an attractive alternative with high pretreatment efficiency, low energy consumption, and easy setup for large-scale applications compared to conventional pretreatment methods. This present review includes an overview of this promising technology and a detailed discussion on the process of parameters that affect the phenomena and future perspectives of development of this area.
The present study is concerned with the batch adsorption of Congo red (CR) from aqueous solutions using calcium alginate beads (CAB) immobilized with dead biomass of Neurospora crassa along with wheat bran (DB-WB) as a dual adsorbent. The optimum conditions for CR adsorption were determined by studying various operational parameters such as initial pH, dye concentration, dual adsorbent loading in CAB, adsorbent dosage, agitation speed, and temperature. The process parameters were optimized using factorial experimental design to attain the maximum percentage adsorption. The CAB immobilized with DB-WB was characterized by attenuated transmission reflector and field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FESEM/EDS) analysis. The experimental equilibrium data were analyzed with various isotherm models. The results show that the best fit was achieved with the Langmuir isotherm model. Kinetic rate constants were found using different kinetic models. The adsorption kinetics for CR dye removal by CAB immobilized with DB-WB dual adsorbent follows pseudo-second-order kinetic model. Thermodynamic studies were performed to determine the change in Gibbs free energy (Delta G), change in enthalpy (Delta H), and change in entropy (Delta S) of the adsorption process. Thermodynamic parameters were evaluated by maximum adsorption capacities (q(max)) at different temperatures. From the results, the adsorption was found to be spontaneous, endothermic in nature of the adsorption process and favored at high temperature. Desorption experiments were carried out using various desorbing agents to explore the possibility of regenerating the CAB immobilized with dual adsorbent. The maximum percentage of CR dye was desorbed using the solvent methanol. The reusability studies of CAB immobilized with dual adsorbent for the adsorption of CR was carried out in three runs.
Biomass pretreatment is an essential step prior to several thermochemical conversion processes. Wet torrefaction, a biomass pretreatment method in hydrothermal media or hot compressed water at temperatures within 180-260 degrees C, has been receiving a lot of attention because it possesses some advantages over other pretreatment methods. Apart from the undoubted benefits of upgrading biomass fuels to closer to coal properties, wet torrefaction has the capacity to work with wet or even extremely wet biomasses and enhance the ash removal from the biomass. The technology has recently attracted great interest from both academic groups and industrial companies. This review aims at providing a comprehensive overview of recent research and development activities in the field with focus on improvements in the chemical, physical and fuel properties of the solid product after wet torrefaction. Moreover, a brief introduction to dry torrefaction, a more conventional thermal pretreatment of biomass in the absence of oxygen under atmospheric pressure and in a temperature range of 200-300 degrees C, is also given and compared with wet torrefaction. Main differences in the properties of the solid products from the two torrefaction methods are also discussed. (C) 2015 Elsevier Ltd. All rights reserved.
Owing to the high demand for construction materials, the construction sector plays an important role in assessing different types of agricultural and mirror industry residues. Consequently, for the first time, a study has been conducted in which residues from the agricultural and mirror industry are used together to contribute to the production of a more environmentally friendly brick. Agricultural irrigation canal (AIC) sludge could not be used alone in brick making because of its low plasticity. Improvement of the plasticity of AIC sludge for the extrusion was achieved with another highly plastic mirror or glass factory residue (MFR) from sand washing process. The two residues as raw materials were mixed at various mass ratios of 90/10, 85/15, 80/20 and 75/25 wt\%, extruded with proper moisture content, dried at 110 degrees C and fired at 950 degrees C and 1050 degrees C, respectively. An increasing amount of MFR in formulations improved both plasticity and compressive strength of bricks. For raw materials, the mineralogical analysis by X-ray diffraction (XRD); chemical analysis by X-ray fluorescence (XRF) and energy-dispersive X-ray analysis (EDX); morphology by scanning electron microscopy (SEM); and thermogravimetric analysis were performed. Plasticities, Bigot's curves and dilatometry analysis of all mixtures were evaluated. Firing shrinkage, apparent density, apparent porosity, water absorption, freeze-thaw resistance, bending strength and compressive strength were determined for fired bricks. These final brick products were also characterised using SEM and XRD. In this study, bricks from AIC sludge and MFR mixtures were showed with a compressive strength in the range of 10-45 MPa. It was found that the bricks made with AIC sludge-MFR 75/25 mixture fired at 1050 degrees C had superior freeze-thaw and mechanical features. The outcomes demonstrated that these two raw materials have adequate characteristics for ceramic brick production.
Background: Butanol as an important chemical and potential fuel could be produced via ABE fermentation from lignocellulosic biomass. The use of food-related feedstocks such as maize and sugar cane may not be a sustainable solution to world's energy needs. Recently, Jerusalem artichoke tubers containing inulin have been used as feedstock for butanol production, but this bioprocess is not commercially feasible due to the great value of inulin as functional food. Till now, there is a gap on the utilization of Jerusalem artichoke stalk (JAS) as feedstock for microbial butanol production. Results: Biobutanol production from JAS was investigated in order to improve cellulose digestibility and efficient biobutanol fermentation. Compared with 9.0 g/L butanol (14.7 g/L ABE) production by 2\% NaOH pretreatment of JAS, 11.8 g/L butanol (17.6 g/L ABE) was produced in the best scenario conditions of NaOH-H2O2 pretreatment, washing times and citrate buffer strengths etc. Furthermore, more than >64\% water in washing pretreated JAS process could be saved, with improving butanol production by >25.0\%. To mimic in situ product recovery for ABE fermentation, the vapor stripping-vapor permeation (VSVP) process steadily produced 323.4-348.7 g/L butanol (542.7-594.0 g/L ABE) in condensate, which showed more potentials than pervaporation for butanol recovery. Conclusions: Therefore, the present study demonstrated an effective strategy on efficient biobutanol production using lignocellulosic biomass. The process optimization could contribute to significant reduction of wastewater emission and the improvement of lignocellulosic biomass digestibility and biobutanol production, which makes biobutanol production more efficient using JAS.
The main intention in the modern era is to make life and activities on earth more comfortable by adding necessary products through biological machinery. Millions of tons of biological raw materials and lignocellulosic biomass are wasted by burning each year without providing benefits to living organisms. Instead of being the cause of disturbing the natural environment by increasing global warming and pollutants worldwide, now, it is the need of the hour to develop an advanced strategy to utilize these biological raw materials to produce renewable energy resources to meet the energy crisis. The review presents the idea of multiple enzymes in one step to hydrolyze complex biomaterials into useful products. The paper discusses how multiple enzymes are arranged in a cascade for complete hydrolysis of raw material in one-pot to prevent multistep, time consuming, and expensive methods. Furthermore, there was the immobilization of multiple enzymes in a cascade system with in vitro and in vivo conditions for reusability of enzymes. The role of genetic engineering, metabolic engineering, and random mutation techniques is described for the development of multiple enzyme cascades. Techniques that are involved in the improvement of native strain to recombinant strain for the enhancement of hydrolytic capacity were used. The preparative steps, before enzymatic hydrolysis like acid, and base treatment methods are more effective for improving the hydrolysis of biomass by multiple enzymes in a one-pot system. Finally, the applications of one-pot multienzyme complexes in biofuel production from lignocellulosic biomass, biosensor production, medicine, food industry, and the conversion of biopolymers into useful products are described.
The disadvantages of conventional methods in water and wastewater management including the demand for high energy consumption, the creation of secondary toxic sludge, and operation cost are much too high for developing countries. However, adsorption using low-cost biosorbents is the most efficient non-conventional technique for heavy metals removal. The high adsorption capacities, cost-effectiveness, and the abundance of agricultural waste materials in nature are the important parameters that explain why these biosorbents are economical for heavy metals removal. The present investigation sought to review the biosorption of lead {[
Filamentous fungal secretomes comprise highly dynamic sets of proteins, including multiple carbohydrate active enzymes (CAZymes) which are able to hydrolyze plant biomass polysaccharides into products of biotechnological interest such as fermentable sugars. In recent years, proteomics has been used to identify and quantify enzymatic and non-enzymatic polypeptides present in secretomes of several fungi species. The resulting data have widened the scientific understanding of the way filamentous fungi perform biomass degradation and offered novel perspectives for biotechnological applications. The present review discusses proteomics approaches that have been applied to the study of fungal secretomes, focusing on two of the most studied filamentous fungi genera: Trichoderma and Aspergillus.
Cows that were subjected to hot environmental temperatures yielded less milk (3.1 kg/d) on a diet high in CP (18.4\%) and of medium degradability (65\%) than on diets high in CP of low degradability (59\%) or medium in CP (16.1\%). The high CP diets were associated with decreased DMI and higher water intake, ruminal NH4, and blood urea. Negative effects on yield from the high CP, medium degradability diet were not observed at moderate temperatures. Evaporative cooling of cows in hot weather resulted in a greater milk yield response to low versus medium rumen-undegradabale protein diets than for uncooled cows. Evaporative cooling of cows also affected response to protein quality. For cooled cows, high Lys diet (soybean, fish, and blood meals) increased milk yield 14\% over that with low Lys diet (com gluten meal), but, for uncooled cows, a high Lys diet only increased yield by 9\%. Percentage of CP, degradability, and protein quality had no effect on body temperatures or respiration rates of lactating cows. Some, but not other, reports showed that supplementation of 2 to 2.5\% fat to diets fed under hot summer conditions resulted in less yield response than when fat was added at moderate temperatures. In several studies, fungal cultures (3 to 5 g/d) in the diet decreased body temperatures and respiration rates in hot, but not cool, weather. Increased milk yields and cellulose digestibility also resulted from dietary fungal cultures in some, but not all, trials. The mechanism of action exerted by fungal cultures on body temperature and respiration rate is unclear.
Pyrolysis is an efficient method for converting this potential environmental contaminant into bio-oil or other products that have specific applications. Recent pyrolysis processes developed to valorize different types of waste, associated with catalytic deoxygenation, was the focus of this review article. The different protocols studied and adopted by different research groups, mainly in the last ten years, revealed that pyrolysis and catalytic deoxygenation are essential for improving the quality of bio-oil. Deoxygenation is considered a simple process for the removal of oxygenated species in bio-oil, allowing its application as biofuel or as a chemical product for other industrial applications, a trend that deserves more attention and studies in its catalytic aspects.
The global dependence on fossil reserves as well as the environmental aspects related to them are some of the factors that propel research on renewable energy forms. Gasification, a thermochemical process that converts carbonaceous resources into syngas, is an advantageous alternative due to its relatively low costs, high efficiencies, and syngas' wide variety of applications. Although gasification is a very promising heat, power, and fuel production technique, there is still a field of improvement in gasification in fluidized beds when it comes to operation under high pressure and with feedstocks containing moderate or high moisture contents. Thus, to provide enough information to address such questions, the present work aims at bringing an overview of gasification concepts, as well as an in-depth discussion based on simulation, laboratory- and demonstration-scale works of the effects of biomass water content and pressure on different parameters of several fluidized bed gasifiers. Moreover, diverse strategies for handling high-moisture content biomass materials are presented, as well as the achievements and technical difficulties encountered by worldwide development and demonstration plant projects that designed and used pressurized fluidized-bed gasifiers.
The review describes different catalysts and reactor-types used in microwave-assisted thermochemical biomass conversion. We present comparative review of various catalytic experiments and experimental conditions using catalysts in both in situ and ex situ processes. In situ catalytic processes are more frequently used due to simpler experimental set up. However, the process leads to higher catalytic deactivation rate and catalyst recovery is difficult. Catalysts used in ex situ processes require a more complex experimental set-up, the advantage being the fact that optimum temperature can be obtained to achieve best results catalyst recovery is facile, and its deactivation occurs at a lower rate. The catalysts described herein represent just a small part of the catalyst types/family that can be theoretically used. Commonly used catalysts are zeolites, metal oxides, various salts or carbon type materials but other materials or improvements of those mentioned need to be tested in the future.
Natural and synthetic polymeric materials are in high demand that continues to increase year after year, making them essential part of human life. By employing cellulose and cellulose derivatives as fillers for either synthetic or natural polymers, the environmental impact of non-biodegradable materials can be reduced. Nanocellulose (NC) materials have recently gained a lot of interest as potential fillers for reinforcing polymeric materials. The article highlights the different sources of NC, including plant sources, marine algae, bacteria and sea animals. The use of dewaxing solvents, alkali, bleaching agents, enzymes, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO), ammonium persulfate (APS), ionic liquids, deep eutectic solvents and steam explosion for pretreatment of lignocellulosic materials was explained. In addition, this review considers the extraction methods, including mechanical fibrillation for the production of cellulose nanofibers (CNF) and acid hydrolysis for the production of cellulose nanocrystals (CNC). Furthermore, the article discusses recent advances in the fabrication of NC polymer composites, such as the melt mixing process, solution casting, 3D printing, electrospinning and pickering emulsions methods. The different characterization techniques of NC polymer composites were discussed in this article. Many promising applications of NC polymer composites, such as sensors, electronics, fuel cells, construction, paper and board, biomedical, food packaging, water purification, aerogels, and hydrogels are considered.
In the past few years, nanocellulose (NC) has gained wide attention due to its renewability, biocompatibility, bioavailability, and different remarkable properties. Cellulose nanomaterials have been broadly studied as materials having a range of applications including in the food industry. Properties such as high surface area and aspect ratio, rheological behavior, water absorption ability, crystallinity, tunable surface chemistry, and no cytotoxicity and genotoxicity of NC enable it to be used in food applications. Nanocellulosic materials like cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial nanocellulose (BNC), have distinctive characteristics which can considerably boost various commercial markets such as packaging. NC has various applications in food such as food stabilizers, dietary fibers, thickeners, flavor carriers, suspension stabilizers and can be used to diminish the caloric value of food. It can also be useful for producing fillings, crushes, biscuits cream, ice cream, chips, wafers, soups, puddings, etc. NC gel has good rheological properties which makes it an interesting candidate in food applications. High viscosity even at lower concentrations of NC makes it remarkable as a non-caloric stabilizing agent and as a gelling agent in food applications. The NC materials have great potential to sustainably improve the tensile and barrier properties while being used as nanofillers in packaging film. This review summarizes the results and prospective applications of cellulose nanomaterials in food applications.
Humic acids (HA) play an important role in the distribution, toxicity, and bioavailability of metals in the environment. Humic-like acids (HLA) that simulate geochemical processes can be prepared by NaOH aqueous extraction from hydrochars produced by hydrothermal carbonization (HTC). HLA can exhibit properties such as those found in HA from soils, which are known for their ability to interact with inorganic and organic compounds. The molecular characteristics of HLA and HA help to explain the relationship between their molecular features and their interaction with metallic species. The aim of this study is to assess the molecular features of HA extracted from Terra Mulata (TM) and HLA from hydrochars as well as their interaction with metals by using Cu(II) ions as a model. The results from C-13 NMR, elemental analysis, FTIR, and UV-Vis showed that HA are composed mostly of aromatic structures and oxygenated functional groups, whereas HLA showed a mutual contribution of aromatic and aliphatic structures as main constituents. The interactions of HA and HLA with Cu(II) ions were evaluated through fluorescence quenching, in which the density of complexing sites per gram of carbon for interaction was higher for HLA than for HA. Furthermore, the HLA showed similar values for stability constants, and higher than those found for other types of HA in the literature. In addition, the average lifetime in both humic extracts appeared to be independent of the copper addition, indicating that the main mechanism of interaction was static quenching with a non-fluorescent ground-state complex formation. Therefore, the HLA showed the ability to interact with Cu(II) ions, which suggests that their application can provide a new approach for remediation of contaminated areas. (C) 2020 Elsevier B.V. All rights reserved.
Acetone and ethanol extraction of lignin deposits from the surface of hydrothermally (liquid hot water) pretreated beech wood biomass alleviates the lignin inhibitory effects during enzymatic hydrolysis of cellulose to glucose and boosts the enzymatic digestibility to high values (approximate to 70 \%). Characterization of the extracted lignins (FTIR, pyrolysis/GC-MS, differential thermogravimetry, gel permeation chromatography) indicated high purity, low molecular weight, and features that suggest that it consists mainly of fragments of the native wood lignin partially depolymerized and recondensed on the biomass surface during the hydrothermal pretreatment. The pyrolysis products of the extracted surface lignins suggest their high potential as a feedstock for the production of high added value phenolic compounds. When the enzymatic hydrolysis of the pretreated and extracted biomass solids was assisted by mild wet milling, near complete cellulose digestibility (>= 95 \%) could be achieved. In the context of the biorefinery and whole-biomass valorization concept, it was also shown that the hydrothermally (hemicellulose-deficient) pretreated and delignified biomass solids could be also successfully used for the production of crude cellulase from Trichoderma reesei cultures, providing a simple and low-cost method for the complementary production of cellulases by utilizing fractions of the integrated hydrolysis process.
Data from 56 bulls of the genetic groups Selection Nellore (NeS), Control Nellore (NeC) and Caracu (Ca) herds born in 1999 were used to evaluate the effects of selection for weight at 378 days of age ( P 378) on the chemical composition of empty body weight. The animals were randomly distributed to three experimental classes: initial slaughter ( AI), restricted feeding (AR) and ad libitum feeding (AL). The AI class included 4 animals of each genetic group and the AR and AL classes included 8 animals from the NeS and Ca groups and 6 animals from the NeC group. After the adaptation period was finished, animals of the AI class were slaughtered and those from the other classes ( AR and AL) started the feeding period which was defined by the time required by the animals of the AL class to reach 4 mm of fat thickness. Animals of the AR class of all genetic groups were also slaughtered. The selection for post-weaning weight did not promote any change on body composition of the animals. The interaction between genetic group and feeding class was not significant for most of the traits evaluated. The genetic group effect was significant. Lower fat and higher protein percentages of empty body were observed in animals of the genetic group Ca, probably due to their larger mature body size.
Solid waste (SW) has become a problem hindering the economic and social development. Achieving the full green cycle from raw material to production of recycled building bricks (RBB) using SW is the focus of future research. In this paper, the research results of RBB manufacturing using SW in recent years are reviewed. According to the consolidation principle of RBB, the effects of different types of SW on the physicochemical properties and microstructure of RBB are summarized based on the recycled unsintered brick (RUSB) and recycled sintered brick (RSB). By comparing and evaluating the two consolidation methods, it is proposed that RSB has good practicality due to its higher SW utilization rate, higher strength, and faster consolidation speed. Furthermore, the difference between MWS and conventional sintering (CS) is analyzed, and the research on the application of MWS in SW-RBB manufacturing in recent years is reviewed in detail. It is pointed out that microwave sintering (MWS) technology can solve many drawbacks in traditional sintering technology and has great prospects in manufacturing SW-RBB due to the low energy consumption, low pollution, and high efficiency. Finally, the shortcomings and possible challenges in the current research on manufacturing SW-RBB using MWS technology are discussed, which provides guidance for the future development of SW-RBB manufacturing.
The presence of dangerous pollutants in different water sources has restricted the availability of this natural resource. Thus, the development of new low-cost and environmentally-friendly technologies is currently required to ensure access to clean water. Various approaches to the recovery of contaminated water have been considered, including the generation of biomaterials with adsorption capacity for dangerous compounds. Research on bioadsorbents has boomed in recent years, as they constitute one of the most sustainable options for water treatment thanks to their abundance and high cellulose content. Thanks to the vast amount of information published to date, the present review addresses the current status of different biosorbents and the principal processes and characterization methods involved, focusing on base biomaterials such as fruits and vegetables, grains and seeds, and herbage and forage. In comparison to other reviews, this work reports more than 60 adsorbents obtained from agricultural wastes. The removal efficiencies and/or maximum adsorption capacities for heavy metals, industrial contaminants, nutrients and pharmaceuticals are presented as well. In addition to the valuable information provided in the literature investigation, challenges and perspectives concerning the implementation of bioadsorbents are discussed in order to comprehensively guide selection of the most suitable biomaterials according to the target contaminant and the available biowastes.
A microwave (MW)-assisted-H2O2 technique used to revise 4-amino-5-hydroxynaphthalene-2,7-disulfonic acid (H-acid)-saturated biochars (BCs) was investigated in detail. This method could simultaneously degrade the H-acid adsorbed in the BCs-based BiFeO3 (BFO) nanocomposites (BFO/BCs), in which BFO was used as dopant intercalated into BC, and activate the used BCs. Because H-acid could be decomposed by OH, which was generated in a coexistent system, including MW irradiation, H2O2, and BCs. It's worth noticing the adsorption capacity was (236.8 mg g(-1)) 1.1-fold higher than that of unused BFO/BC (211.7 mg g(-1)). It indicated that the surplus \% OH exhibited a cooperative effect with MW irradiation to restore H-acid-saturated BCs via the cleavage of C=C bond, thereby forming carboxylic groups and the pyrolysis effect. Findings indicated that the one-step degradation-regeneration method could effectively promote the adsorption capacity of H-acid-saturated BCs in a few minutes and could thus be considered a potential technology in water treatment.
The adsorption behavior of cadmium on husk of lentil an agro-waste was investigated to understand the mechanism of adsorption as well as to explore its potential in removing cadmium from its aqueous solution. The adsorption process of lentil husk (LH) was found to be a function of pH of the solution, optimum being 5.0. The rate of adsorption of cadmium by LH was very fast initially and attained equilibrium within 60 min following pseudo second order rate kinetics. The study established that 1.0 g LH can adsorb 107.31 mg of cadmium and was successful to reduce the concentration of this metal from the effluent of battery industries. Adsorption process followed Langmuir isotherm model with uniform distribution of metal ions on the surface of the biomass as revealed from X-ray elemental mapping. In binary system the biomass displayed a preference in adsorption of lead over cadmium. The results of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), chemical modification of functional groups and zeta potential measurement established the binding of cadmium to the biomass through electrostatic and complexation reactions. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Grain stillage from the liquor industry was pretreated by using microwave-assisted hydrothermal pretreatment, fungal pretreatments, and their combination to enable efficient enzymatic hydrolysis for sugar production. The microwave-assisted hydrothermal (MH) pretreatment was optimized by using a response surface methodology, and the respective maximum reducing sugar yield and saccharification efficiency of 17.59 g/100 g and 33.85\%, respectively, were achieved under the pretreatment conditions of microwave power = 120 W, solid-to-liquid ratio = 1:15 (g.mL(-1)), and time = 3.5 min. The fungal pretreatment with Phanerochaete chrysosporium digestion (PC) achieved the maximum ligninolytic enzyme activities in 6 days with 10\% inoculum size at which the reducing sugar yield and saccharification efficiency reached 19.74 g/100 g and 36.29\%, respectively. To further improve the pretreatment efficiency, MH and PC pretreatments were combined, but the sequence of MH and PC mattered on the saccharification efficiency. The MH + PC pretreatment (the MH prior to the PC) was better than PC + MH (the PC prior to the MH) in terms of saccharification efficiency. Overall, the MH + PC pretreatment achieved superior reducing sugar yield and saccharification efficiency (25.51 g/100 g and 66.28\%, respectively) over all other studied pretreatment methods. The variations of chemical compositions and structure features of the raw and pretreated grain stillage were characterized by using scanning electron microscopy and Fourier transform infrared spectroscopy. The results reveal that both MH and PC pretreatments mainly functioned on delignification and decreasing cellulose crystallinity, thus enhancing the enzymatic saccharification of the pretreated grain stillage. The combined MH and PC pretreatment could be a promising method to enable cost-efficient grain stillage utilization for downstream applications such as biofuels.
This review paper briefly introduces the radiation chemistry of cellulose, the different grafting techniques used, and the methods of characterization of the grafted material. It shows the application of the grafted polymer for the removal of water pollutants and also the regeneration of the adsorbent. (C) 2010 Elsevier Ltd. All rights reserved.
Economic growth and industrial energy demand necessitate sustainable energy resources. The food vs. fuel issue means that first generation biofuels appear unsustainable. Therefore, biofuel production using lignocellulosic biomass clearly needs to be explored and promoted. However, due to technological barriers, the production of biofuel from lignocellulose (second generation biofuel) is currently not cost effective. Although microbial fermentation is an ecofriendly way to convert lignocellulose into biofuel, it will take time to become a commercial reality. Biofuels of different generations can contribute synergistically to fulfill energy demand. More research and government participation is needed to make the biofuel production process more feasible. This review focuses on the pretreatment of biomass, the production of biofuel (biodiesel, bioalcohol, and biogas) using microbial systems, and the various efforts that have been implemented to improve biofuel production. (C) 2017 Elsevier Ltd. All rights reserved.
Research in the field of packaging materials demands the need for greener methods to reduce carbon footprint as well as to encourage green chemistry protocols. Several polymerized materials are being used in the field of packaging primal matter, which may cause environmental pollution and a rise in energy and resource demands. On considering this, researchers begin to focus on plant-based nano-cellulose, which have the capability for the preparation of materials for packaging. Cellulose is a biopolymer that is accessible in enormous amounts, with a fascinating combination of different properties. As established by several research groups, plant-based nano-cellulose is a biocompatible and nontoxic candidate whose rheological, mechanical and gas barrier properties are modest related to conventional oil-based plastics. Since polymer nanocomposites own unique material properties by combining the qualities of both nanofiller and polymer matrix, we can prepare cellulose-based nanocomposites by using cellulose as nanofillers. Such materials show an improved barrier property, increased heat distortion temperature, higher modulus and strength. This review discusses the synthesis, characterizations, properties and various uses of cellulose-based polymer nanocomposites in the packaging industry.
Anaerobic digestion is one of the main waste-to-energy technologies in reducing the volume of biodegradable waste into energy-rich biogas. Recent studies have revealed that kitchen wastes as a feedstock possess great potential in energy production and anaerobic digestion proved to be a promising technology among different kitchen waste management techniques such as incineration, pyrolysis, gasification, landfills, composting, etc. To anaerobically treat feedstock, an airtight enclosed container commonly known as biodigester will be employed. To suffice the energy requirement for cooking in the rural areas and recently even in the urban areas, a small-scale biogas unit commonly referred to as portable type biodigester is blooming as an attractive alternative for the production of biogas domestically. Hence, this review emphasizes on anaerobic digestion of kitchen wastes and the design of portable type biodigester. The present review provides an overview of different kitchen waste management techniques. The paper also discusses the different types of biomass feedstock and provides a generalized procedure for the design of a portable biogas unit. This study confirms that the systematic design of biogas units and proper feeding of kitchen waste offers an advantage of effective utilization of wastes in the production of decentralized energy.
Zymomonas mobilis is an ethanologenic microbe that has a demonstrated potential for use in lignocellulosic biorefineries for bioethanol production. Z. mobilis exhibits a number of desirable characteristics for use as an ethanologenic microbe, with capabilities for metabolic engineering and bioprocess modification. Many advanced genetic tools, including mutation techniques, screening methods and genome editing have been successively performed to improve various Z. mobilis strains as potential consolidated ethanologenic microbes. Many bioprocess strategies have also been applied to this organism for bioethanol production. Z. mobilis biofilm reactors have been modified with various benefits, including high bacterial populations, less fermentation times, high productivity, high cell stability, resistance to the high concentration of substrates and toxicity, and higher product recovery. We suggest that Z. mobilis biofilm reactors could be used in bioethanol production using lignocellulosic substrates under batch, continuous and repeated batch processes.
Major sugar constituents in young coconut husk were found to be glucans (0.30 g/g husk), while xylans were 0.10 g/g husk. Pre-treatments were carried out using phosphoric acid with dried coconut husk powder under steam heating. The effect of phosphoric acid on coconut husk hydrolysis was observed using acid concentrations of 0\%, 1\%, 5\% and 10\% (v/v). Soluble sugar concentration in hydrolysate was increasing proportional to acid concentration, as the total recovered solid decreases. FTIR and XRD analysis showed that acid hydrolysis led to the disruption of internal chemical bonds, causing coconut husk structural sugars to be released into the hydrolysate. Highest soluble sugar concentration, 29.9 g/L with a total suspended solid of 75.1 g/L, was obtained when the coconut husk was pre-treated with 10\% phosphoric acid, and can be utilised for biohydrogen fermentation. Biotoxicity testing of the hydrolysates shows that half-maximal inhibition concentration of phosphoric acid was around 4.41\% for a 24-h incubation and 3,80\% for a 96-h incubation. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
This article summarizes current utilizations of wood cell wall components in relation to biorefinery of woody biomass as a separation method of its constituents. Especially, utilization of isolated lignins, involving transformation and molding, are demonstrated with respect to productions of carbon fibers and their further functionalization, such as developments of activated carbon fibers and electrodes for second battery and electric double-layer capacitor.
Production of high value biochemicals from lignocellulose biomass via pyrolysis, particularly levoglucosan (LG) has received immense attention in recent years. LG production via fast pyrolysis has recorded a continuous development over the past years, which demands a state-of-the-art review, covering the LG recovery methods and commercial feasibility analysis of the process. This paper provides an in-depth review of the progress and current status of bio-LG production with a focus on formation mechanisms, influential variables, recovery methods and techno-economic prospects. Based on the experimental findings of the previous studies, this review concluded that the LG yield from biomass via pyrolysis could be proposed as a function of biomass structural properties, cellulose content, inorganic minerals content as well as pyrolysis process conditions. An essential aspect of maximising the overall efficiency of LG production process is the adoption of efficient in-situ or postpyrolysis LG extraction techniques, which has been critically reviewed for the first time. The paper also summarises the techno-commercial assessment studies of LG facility, highlighting the limiting factors towards the economic attractiveness of the process. Finally, the review highlights the knowledge gaps and provides future recommendations, which will be helpful for the improvement of productivity and economic feasibility of bio-LG production process.
Fulvic acids (FA) are one of the components of humic substances and play an important role in the interaction with metallic species and, consequently, the bioavailability, distribution and toxicity of metals. However, only a few studies have investigated these FA properties in specific environment, such as anthropogenic soils. Therefore, knowledge about FA molecular composition as well as the FA-metal interaction is essential to predict their behavior in the soil. For this reason, the aim of this study was to investigate the molecular composition of FA extracted from two sites in an anthropogenic soil (Terra Mulata), from the Amazon region, as well as their interactions with Cu(II) ions as a model. Results from C-13 NMR, infrared and elemental analysis showed that these FA are composed mostly by alkyl structures and oxygen-functional groups, e.g., hydroxyl, carbonyl and carboxyl. The interaction with Cu(II) ions was evaluated by fluorescence quenching, in which the FA showed both high quantity of complexing sites per gram of carbon and good affinity to interact with the metal when compared with other soil FA. The results showed that the complexation capacity was highly correlated by the content of functional groups, while the binding affinity was largely influenced by structural factors. In addition, through the lifetime decay given by time-resolved fluorescence, it was concluded that static quenching took place in FA and Cu(II) interaction with the formation of a non-fluorescent ground-state complex. Therefore, this fraction of soil organic matter will fully participate in complexation reactions, thereby influencing the mobility and bioavailability of metal in soils. Hence, the importance of the study, and the role of FA in the environment, can be seen especially in the Amazon, which is one of the most important biomes in the world.
Lignocellulosic biomasses are primarily composed of cellulose, hemicelluloses and lignin and these biopolymers are bonded together in a heterogeneous matrix that is highly recalcitrant to chemical or biological conversion processes. Thus, an efficient pretreatment technique must be selected and applied to this type of biomass in order to facilitate its utilization in biorefineries. Classical pretreatment methods tend to operate under severe conditions, leading to sugar losses by dehydration and to the release of inhibitory compounds such as furfural (2-furaldehyde), 5-hydroxy-2-methylfurfural (5-HMF), and organic acids. By contrast, supercritical fluids can pretreat lignocellulosic materials under relatively mild pretreatment conditions, resulting in high sugar yields, low production of fermentation inhibitors and high susceptibilities to enzymatic hydrolysis while reducing the consumption of chemicals, including solvents, reagents, and catalysts. This work presents a review of biomass pretreatment technologies, aiming to deliver a state-of-art compilation of methods and results with emphasis on supercritical processes.
Technoeconomic analysis of multiple-stream lignin and ethanol production from 100 Mt/h of industrial hemp biomass is conducted based on three scenarios: I, H2SO4 pretreatment and NaOH neutralization; II, parallel HOAc and NaOH pretreatments, solid separation, and liquid integration; and III, parallel H2SO4 and NaOH pretreatments, solid separation, and liquid integration. The technical and economic advantages and disadvantages of the three processing scenarios with different production technologies are discussed. A discounted cash flow rate of return assessment is executed to ascertain the ethanol minimum selling price (MSP). The chemical reagent used for pretreatment is found to have a significant impact on economic aspects with an annual operating cost of \$628.34 million for scenario II, which is strikingly higher than \$367.97 million for scenario I and \$347.86 million for scenario III. The advantage of the largest lignin and ethanol output with a total revenue of \$190.53 million annually for scenario II is offset by its high total capital investment and operating cost. Scenario III reaches the lowest ethanol MSP of \$6.16/gal compared to \$9.04/gal from scenario I and \$10.26/gal from scenario II, indicating that parallel H2SO4 and NaOH pretreatments with subsequent integration are more efficient than a single H2SO4 pretreatment. Sensitivity analyses identify biomass and reagent costs and glucose-to-ethanol yield as the dominant contributors to the ethanol MSP. Although the present biorefineries are not profitable yet, this study might provide new perspectives for biomass valorization in terms of chemical selection and engineering design.
Developing an effective cleaner process technology for maize-cob biomass wastes is of utmost importance. This work involved the comparison of products yield (bio-oil, biogas, and biochar) from the fast, slow, and flash pyrolysis of maize-cob biomass wastes using a fixed-bed reactor; evaluation of the individual and combined influences of pyrolysis temperature, biomass particle size, and residence time on the yield of product, and the determination of the optimum pyrolysis conditions/products yield of fast pyrolyzed maize-cob. The fast pyrolysis was performed according to the Box-Behnken Design of Experiment with three variables and three levels of the response surface methodology. The bio-oil fuel properties were determined utilizing ASTM methods and chemically characterized using CHNS elemental analyzer, GC/MS, and FTIR. The performance of the three pyrolysis techniques in terms of their product yield is in the following order: Flash pyrolysis > Fast pyrolysis > Slow pyrolysis (for bio-oil); Slow pyrolysis > Fast pyrolysis > Flash pyrolysis (for biochar and biogas). An optimum bio-oil yield of 43.13\% with a high heating value (HHV) of 30.59 MJ/kg, biochar yield of 37.18\% with HHV of 20.41 MJ/kg, and biogas yield of 26.05\% (HHV = 13.19 MJ/kg) was respectively obtained at an optimum temperature of 567.72, 463.71, and 593.17 degrees C; biomass particle size of 0.51, 3.83, and 2.58 mm; and residence time of 10.01, 15.28, and 18.92 min. The determined physicochemical characterized properties of the maize-cob-derived-bio-oil revealed that the bio-oil can potentially be valued as a biofuel and as a more promising feedstock for value-added chemical production.
Lignocellulose revalorization has emerged as a major solution to mitigate the increasing energy demand of the growing population. Lignocellulosic biomass is considered the building block of plant cell walls and is mainly composed of cellulose, hemicellulose, and lignin. The biomass needs to be processed efficiently to produce value-added products and bioenergy. Therefore, this study aims to systematically review various conversion technologies, like thermal conversion, and biological pretreatments available to achieve this. The use of the biological pretreatment method is cost-effective and eco-friendly. Many microorganisms, different strains of bacteria, fungus, etc., are used here to exploit their cellulolytic and ligninolytic properties. It covers the life cycle assessment of lignocellulose pretreatment, downstream processing for conversion of lignocellulose to biofuel, and techno-economic analysis. The attention has also been given to the development of biorefineries to enhance the production efficiency of bioenergy from the lignocellulosic biomass.
Papiliotrema laurentii, previously classified as Cryptococcus laurentii, is an oleaginous yeast that has been isolated from soil, plants, and agricultural and industrial residues. This variety of habitats reflects the diversity of carbon sources that it can metabolize, including monosaccharides, oligosaccharides, glycerol, organic acids, and oils. Compared to other oleaginous yeasts, such as Yarrowia lipolytica and Rhodotorula toruloides, there is little information regarding its genetic and physiological characteristics. From a biotechnological point of view, P. laurentii can produce surfactants, enzymes, and high concentrations of lipids, which can be used as feedstock for fatty acid-derived products. Moreover, it can be applied for the biocontrol of phytopathogenic fungi, contributing to quality maintenance in post- and pre-harvest fruits. It can also improve mycorrhizal colonization, nitrogen nutrition, and plant growth. P. laurentii is also capable of degrading polyester and diesel derivatives and acting in the bioremediation of heavy metals. In this review, we present the current knowledge about the basic and applied aspects of P. laurentii, underscoring its biotechnological potential and future perspectives.
The industrial waste products have been annually generated crossing a limit of 1000 million tons leading to numerous hazards to the environment. The generated based products are getting dumped causing soil pollution, and it is harmful. The best solution is to wisely introduce these waste materials for producing sustainable concrete. This review focuses on incorporating the industrial waste products as a sustainable effective substitute to cement in the development of self-compacting concrete in accordance with the prevailing literature works. Generally, self-compacting concrete is produced with higher cement content combined with the water, aggregates, and chemical admixtures. The consumption of higher cement leads to the emission of larger amount of carbon dioxide triggering the hazardous environmental effects. These impacts could be lowered by utilizing the industrial waste products as partial cementitious replacement in concrete. The comprehensive review on the chemical properties, physical properties, and material characterizations was investigated for the industrial waste products to assess the suitability of the cement properties. A detailed review was conducted on the implementation of industrial waste products such as fly ash, ground granulated blast furnace slag, metakaolin, microsilica and nanosilica on the aspects of fresh concrete properties, strength properties, and durability characteristics when used as partial cement replacement materials. This paper abridges the credits and critical challenges of effectively utilizing industrial waste products toward the sustainable development of the eco-friendly self-compacting concrete.
While lignin has been gaining wide research interest for a variety of applications across many industries, relatively little work has been published on its applications in nonwovens. Consequently, this article offers an overview of the underlying principles and both the present and future applications of lignin within the nonwoven industry. Due to the distinct structure of lignin, processing, fiber production, composites with polymers, dye dispersant, and fire-retardant applications are all unique opportunities for lignin application in nonwovens discussed in this review. Conventional nonwoven processing techniques, such as electrospinning, have been reported to successfully produce lignin-based nonwovens, specifically lignin/polymer composite nonwovens. This account points to pivotal polymer matrix/lignin composite compatibility issues that define various processing technologies. However, lignin use is not limited to incorporation within nonwoven fibers mats and is currently used in dye dispersion with the potential of phase out petroleum-based dye dispersants. Finally, the high phenolic content of lignin endows it with fire-retardant and antimicrobial properties, among others, that present additional opportunities for lignin in the nonwoven industry. Throughout this review, an effort is made to outline the advantages and challenges of using lignin as a green and sustainable ingredient for the production of nonwoven materials.
Recently, the development of efficient and environmentally benign solvents has received great attention to replace current harsh organic solvents. In this context, low-transition-temperature mixtures (LTTMs) have emerged as favorable green solvents for biomass delignification. Palm oil biomass, empty fruit bunch (EFB) was pretreated with commercial l-malic acid and microwave hydrothermally extracted cactus malic acid-derived LTTMs at 60, 80, and 100 degrees C. The LTTMs applied in this study were derived from malic acid-choline chloride-water and malic acid-monosodium glutamate-water with a molar ratio of 2:4:2 and 3:1:5, respectively. Three first-order reactions were used to express the delignification kinetic model of EFB. The first term was based on the initial stage and assigned as infinite due to the fast rate of delignification which could not be detected. The second and third terms were proportional to bulk and residual delignification stages. A good agreement was obtained between the kinetic model and the experimental data obtained in this study with R(2)0.91. The activation energies for the delignification reactions using l-malic acid and cactus malic acid-based LTTMs in the bulk and residual stages were approximated as 36-56 and 19-26kJ/mol and 34-90 and 47-87kJ/mol, respectively.
To expand the use of renewable materials, paper products with superior mechanical and optical properties are needed. Although beating, bleaching, and additives are known to improve industrially produced Kraft pulp papers, properties are limited by the quality of the fibers. While the use of nanocellulose has been shown to significantly increase paper properties, the current cost associated with their production has limited their industrial relevance. Here, using a simple mild peracetic acid (PAA) delignification process on spruce, we produce hemicellulose-rich holocellulose fibers (28.8 wt \%) with high intrinsic strength (1200 MPa for fibers with microfibrillar angle smaller than 10 degrees). We show that PAA treatment causes less cellulose/hemicellulose degradation and better preserves cellulose nanostructure in comparison to conventional Kraft pulping. High-density holocellulose papers with superior mechanical properties (Young's modulus of 18 GPa and ultimate strength of 195 MPa) are manufactured using a water-based hot-pressing process, without the use of beating or additives. We propose that the preserved hemicelluloses act as ``glue{''
The biosorption of the anionic dye Congo red from aqueous solution onto the novel biosorbents Aspergillus carbonarius and Penicillium glabrum was studied. Optimum sorption conditions were identified by varying solution pH, initial dye concentration, contact time and temperature. The obtained results showed that BET surface area of Penicillium glabrum biosorbent (6.31 m(2)/g) was larger than that of Aspergillus carbonarius biomass (5.07 m(2)/g). The microstructures of the fungi were observed with scanning electron micrographs. Chemical characterization of both micro-fungi was carried out by Fourier Transform Infrared Spectroscopy (FT-IR). The biosorption data have been analyzed using Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Sips isotherms. Based on R-2, the equilibrium sorption data was better fitted to Langmuir isotherm model than any other model. The biosorption processes conformed to the pseudo second-order rate kinetics. Maximum biosorption capacity was found to be 99.01 mg/g for Aspergillus carbonarius and 101.01 mg/g for Penicillium glabrum at pH 4.5, 0.33 g/L sorbent dosage, 180 min contact time and 303 K for dye initial concentration of 50 ma. Thermodynamic parameters of the biosorption (Delta G degrees, Delta H degrees and Delta S degrees) were also determined and it was found that the biosorption of dye by Aspergillus carbonarius and Penicillium glabrum was a spontaneous process and endothermic in nature. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Plant cellulose fibers are a biodegradable and acceptable alternative for fabricating balanced-strength polymer laminate components due to their higher specific strength, eco-friendliness, and renewable nature. The target of the present investigation is to manufacture banana-boron nitride-carbon fabric and coir-multi walled carbon nanotubes-Innegra fabric hybrid polyester laminates by varying different chemical treatments and determine the physical (density, water absorption, and contact angle), mechanical (tensile, flexural, interlaminar shear, impact strength, and shore D hardness) and thermal (onset, endset, glass transition temperature, and carbon residue) characteristics of fabricated laminates. The addition of chemically treated/ untreated banana/ coir fillers in the polyester matrix was affirmed morphologically and structurally from Fourier Transform Infra-Red (FTIR) spectra and scanning electron microscope (SEM). Differential scanning calorimeter (DSC) and Thermogravimetric analysis (TGA) results examined the higher thermal stability of the chemically treated banana/ coir fiber reinforced polyester hybrid laminates around 400 degrees C. The artificial neural network modeling was performed to select the best composite material among the fabricated laminates. The determination coefficient values were lower than 0.98 for testing, validation, and training for both laminates. The model outcomes exhibited lower root mean squared error, explaining that using the model of an exact threshold was predicted for the artificial neural network forecasting. The one way-Analysis of variance (ANOVA) technique was applied to study the significance of the difference between the chemically treated/ untreated banana and coir fillers on physical, mechanical, and thermal characteristics.
The development of agricultural waste-doped fired bricks is an important step toward achieving lightweight eco-efficient bricks with improved thermal insulation property. Recent research in masonry has been tailored towards the production of energy-efficient building by incorporating waste materials as additives. This effectuates a safe waste disposal, cost effectiveness, and also serve as a giant stride towards environmental sustainability. This study examines the viability of using walnut shell as additive in fired clay at various firing temperatures. Pulverized walnut shell was added to clay at a proportion of 0-10 wt.\% by weight of clay. The samples were fired at temperatures of 950 degrees C and 1100 degrees C. The samples were probed for mechanical properties and durability. Morphology of the brick samples were examined under scanning electron microscope. The result of the research showed increased water absorption and specific heat capacity while mechanical and bulk density were observed to reduce. Linear shrinkage and thermal conductivity reduced with increase in walnut content of which linear shrinkage and thermal conductivity values experienced at 1100 degrees C was higher than at 950 degrees C. Resistance of bricks to salt crystallization increased with firing temperature. All samples met various standard requirement for masonry except sample prepared with 10 wt.\% walnut shell whose compressive and flexural strengths fell below the required standard. The study established the use of walnut shell for development of sustainable energy-efficient bricks.
Biomass is considered as the most sustainable and renewable resource for the synthesis of value added potential platform chemicals. Various techniques are utilized to extract or to pre-treat or to isolate various value added chemicals from biomass. Pre-treatment of the biomass is a very essential aspect to enhance the biomass processing yield which is attributed to reduced lignin content/delignification, cellulose crystallinity and hemi-cellulose hydration. In search of efficient extraction and processing for biomass treatment, supercritical fluid (SCF) has been considered as the green technique to obtain the value added chemicals with higher efficiency than conventional technique. The use of the supercritical carbon dioxide (SC-CO2) pre-treatment on biomass not only enhances glucose yield effectively but also delignify, hydrolyse hemi-cellulose component and allows extraction of various compounds from the biomass. However, very limited research articles are available for the use of SC-CO2 for biomass processing to obtain value-added chemicals. In view of this, the present review article focus on the recent advances of applications of SC-CO2 in (i) extraction of value added chemicals from biomass processing, (ii) biomass pre-treatment, (iii) factors affecting SC-CO2 processing efficiency, (iv) scale-up scenario (v) challenges and opportunities in this field.
A large quantity of Rice husk ash (RHA) is disposed of as waste material and leads to severe pollution. The pozzolanic behaviour of RHA enables its application in the construction sector, which is an alternative solution to its disposal. This paper critically reviews the use of RHA in the cleaner production of construction products such as blended cement, alkali activated binder, and bricks. The use of RHA in other construction applications such as soil stabilisation and subgrade treatment are also reviewed. Moreover, scientific insights on the physical, chemical, and mineralogical properties of RHA, which plays an important role in the engineering properties of RHA blended construction products, are presented. On assessing the effect of RHA on different construction sectors, the addition of 10-20\% of RHA is reported to enhance the short term and long term engineering properties of construction products. Hence, RHA is energy and cost-effective solution for the construction industry. In addition, based on the extensive review, the paper also provides pathways and recommendations for utilisation of RHA in the cleaner production of construction. (C) 2020 Elsevier Ltd. All rights reserved.
In this work, the catalytic deoxygenation of waste cooking oil (WCO) over acid-base bifunctional catalysts (NiLa, NiCe, NiFe, NiMn, NiZn, and NiW) supported on activated carbon (AC) was investigated. A high hydrocarbon yield above 60\% with lower oxygenated species was found in the liquid product, with the product being selective towardn-(C-15+ C-17)-diesel fractions. The predominance ofn-(C-15+ C-17) hydrocarbons with the concurrent production of CO and CO2, indicated that the deoxygenation pathway proceededviadecarbonylation and decarboxylation mechanisms. High deoxygenation activity with bettern-(C-15+ C-17) selectivity over NiLa/AC exposed the great synergistic interaction between La and Ni, and the compatibility of the acid-base sites increased the removal of oxygenated species. The effect of La on the deoxygenation reaction performance was investigated and it was found that a high percentage of La species would be beneficial for the removal of C-O bonded species. The optimum deoxygenation activity of 88\% hydrocarbon yield with 75\%n-(C-15+ C-17) selectivity was obtained over 20\% of La, which strongly evinced that La leads to a greater enhancement of the deoxygenation activity. The NiLa/AC reusability study showed consistent deoxygenation reactions with 80\% hydrocarbon yield and 60\%n-(C-15+ C-17) hydrocarbon selectivity within 6 runs.
Six agro-industrial wastes were evaluated as a support for ligninolytic enzyme production by the white-rot fungus Lentinus polychrous Lev. under solid-state fermentation. Enzyme production was markedly different according to the substrate used. Rice bran (RB) yielded the highest laccase activity of 1,449 U/L (after 21 days of culture) with specific activity of 4.4 U/g substrate. Rice bran supplemented with rice husk (RH) (21 by wt) showed high laccase activity of 1,425 U/L with specific activity of 10.0 U/g substrate (after 17 days of culture). The crude enzyme of the RH-RB culture also contained manganese peroxidase (MnP) and manganese-independent peroxidase (MIP) activities in relative proportions of 1.9:1.4:1 of laccase:MnP:MIP, respectively. Zymogram studies showed the same isoenzyme pattern with these ligninolytic enzymes. The high enzyme production level and low substrate cost of SSF-L. polychrous Lev. suggest that it has potential for industrial applications. Our studies showed that the crude enzyme from this culture exhibited in vitro decolorization of Indigo Carmine. The highest efficiency of dye decolorization was observed under alkaline conditions (pH 9.0) at an initial dye concentration of 10 mg/L. The rather high pH conditions and high efficiency in Indigo Carmine decolorization make the enzyme further interest for the applications in treatment of waste water from the textile industry, which contains synthetic dyes. (C) KSBB
Background: Functional foods are receiving high interest and attracting global attention due to their therapeutic health benefits. Xylooligosaccharides (XOS) are potential prebiotics that has attained commercial interest due to their prospective application in the food industry and its beneficial effects on human wellness. The demand to create alternate natural sources is steadily increasing to meet the consumer and industry needs for safe foods. Scope and approach: The review summarizes the various strategies employed in xylan extraction, XOS production (chemical and enzymatic) and characterization. The study also critically views the physiological importance and biological effects described through various in vitro and in vivo intervention studies. The technological properties, food-based applications and the future perspectives of XOS are presented. Key findings and conclusions: A better utilization of XOS to exert a positive impact on health would help to the functional foods and nutraceuticals future markets.
The radiation-induced degradation of cellulose is analyzed taking into account the effect of temperature on the formation and interconversion of macroradicals. Non-chain depolymerization, consisting in the random cleavage of glycosidic bonds, occurs at low and moderate temperatures. As a result, oligomeric polysaccharides are formed in which the C:O:H atomic ratio is only slightly different from the original one. When the hydrogen bonds disappear and the fragmentary radicals are thermally generated, the depolymerization can proceed via the chain mechanism. Another mechanism, which we term self-disassembly, consists in consecutive shortening the polymer chain from its end at pre-pyrolysis temperatures. It is realized via the dehydration of macroradicals and leads to the elimination of monocyclic furans.
In search to increase the offer of liquid, clean, renewable and sustainable energy in the world energy matrix, the use of lignocellulosic materials (LCMs) for bioethanol production arises as a valuable alternative. The objective of this work was to analyze and compare the performance of Saccharomyces cerevisiae, Pichia stipitis and Zymomonas mobilis in the production of bioethanol from coconut fibre mature (CFM) using different strategies: simultaneous saccharification and fermentation (SSF) and semi simultaneous saccharification and fermentation (SSSF). The CFM was pretreated by hydrothermal pretreatment catalyzed with sodium hydroxide (HPCSH). The pretreated CFM was characterized by X-ray diffractometry and SEM, and the lignin recovered in the liquid phase by FTIR and TGA. After the HPCSH pretreatment (2.5\% (viv) sodium hydroxide at 180 degrees C for 30 min), the cellulose content was 56.44\%, while the hemicellulose and lignin were reduced 69.04\% and 89.13\%, respectively. Following pretreatment, the obtained cellulosic fraction was submitted to SSF and SSSF. Pichia stipitis allowed for the highest ethanol yield 90.18\% in SSSF, 91.17\% and 91.03\% were obtained with Saccharomyces cerevisiae and Zymomonas mobilis, respectively. It may be concluded that the selection of the most efficient microorganism for the obtention of high bioethanol production yields from cellulose pretreated by HPCSH depends on the operational strategy used and this pretreatment is an interesting alternative for add value of coconut fibre mature compounds (lignin, phenolics) being in accordance with the biorefinery concept. (C) 2016 Elsevier Ltd. All rights reserved.
Lignocellulosic biomass (LB) is a promising sugar feedstock for biofuels and other high-value chemical commodities. The recalcitrance of LB, however, impedes carbohydrate accessibility and its conversion into commercially significant products. Two important factors for the overall economization of biofuel production is LB pretreatment to liberate fermentable sugars followed by conversion into ethanol. Sustainable biofuel production must overcome issues such as minimizing water and energy usage, reducing chemical usage and process intensification. Amongst available pretreatment methods, microorganism-mediated pretreatments are the safest, green, and sustainable. Native biodelignifying agents such as Phanerochaete chrysosporium, Pycnoporous cinnabarinus, Ceriporiopsis subvermispora and Cyathus stercoreus can remove lignin, making the remaining substrates amenable for saccharification. The development of a robust, integrated bioprocessing (IBP) approach for economic ethanol production would incorporate all essential steps including pretreatment, cellulase production, enzyme hydrolysis and fermentation of the released sugars into ethanol. IBP represents an inexpensive, environmentally friendly, low energy and low capital approach for second-generation ethanol production. This paper reviews the advancements in microbial-assisted pretreatment for the delignification of lignocellulosic substrates, system metabolic engineering for biorefineries and highlights the possibilities of process integration for sustainable and economic ethanol production.
Lignocellulosic biomass is recalcitrant to biodegradation due to the rigid and compact structure of plant cell wall. The recalcitrance of biomass is mainly constructed by its chemical compositions that build a spatial network as a protective bulwark. Generally, the factors affecting the accessibility of biomass cellulose can be divided into direct and indirect factors. The direct factors refer to the accessible surface area, and the indirect factors include biomass structure-relevant factors (pore size and volume, particle size, and specific surface area), chemical compositions (lignin, hemicelluloses, and acetyl group), and cellulose structure-relevant factors (cellulose crystallinity and degree of polymerization). Pre-treatment is actually the process to alter indirect factors and improve direct factors thus enhancing the accessibility of cellulose. In this review, we summarize the effects of chemical compositions and physical structures on the enzymatic digestibility of lignocellulosic biomass. We suggest that future work should be focused on but not limited to the molecular mechanisms of biomass recalcitrance by investigating the microscale and nanoscale features as well as hydrogen bonds network of lignocellulosic biomass. (C) 2012 Society of Chemical Industry and John Wiley \& Sons, Ltd
Enzymatic hydrolysis is a critical process for the cellulase-mediated lignocellulosic biorefinery to produce sugar syrups that can be converted into a whole range of biofuels and biochemicals. Such a process operating at high -solid loadings (i.e., scarcely any free water or roughly >= 15\% solids, w/w) is considered more economically feasible, as it can generate a high sugar concentration at low operation and capital costs. However, this approach remains restricted and incurs ``high-solid effects{''
As one of the largest carbon emitters, China promises to achieve carbon emissions neutrality by 2060. Various industries are developing businesses to reduce carbon emissions. As an important greenhouse gas emissions scenario, the reduction of carbon emissions in the food chain can be achieved by preparing the wastes into biochar. The food chain, as one of the sources of biochar, consists of production, processing and consumption, in which many wastes can be transferred into biochar. However, few studies use the food chain as the system to sort out the raw materials of biochar. A systematic review of the food chain application in serving as raw materials for biochar is helpful for further application of such technique, providing supportive information for the development of biochar preparation and wastes treating. In addition, there are many pollution sources in the food production process, such as agricultural contaminated soil and wastewater from livestock and aquatic, that can be treated on-site to achieve the goal of treating wastes with wastes within the food chain. This study focuses on waste resource utilization and pollution remediation in the food chain, summarizing the sources of biochar in the food chain and analyzing the feasibility of using waste in food chain to treat contaminated sites in the food chain and discussing the impacts of the greenhouse gas emissions. This review provides a reference for the resource utilization of waste and pollution reduction in the food chain.
The increasing agro-demands with the burgeoning population lead to the accumulation of lignocellulosic resi-dues. The practice of burning agri-residues has consequences viz. Release of soot and smoke, nutrient depletion, loss of soil microbial diversity, air pollution and hazardous effects on human health. The utilization of agri-cultural waste as biomass to synthesize biochar and biofuels, is the pertinent approach for attaining sustainable development goals. Biochar contributes in the improvement of soil properties, carbon sequestration, reducing greenhouse gases (GHG) emission, removal of organic and heavy metal pollutants, production of biofuels, syn-thesis of useful chemicals and building cementitious materials. The biochar characteristics including surface area, porosity and functional groups vary with the type of biomass consumed in pyrolysis and the control of parameters during the process. The major adsorption mechanisms of biochar involve physical-adsorption, ion-exchange interactions, electrostatic attraction, surface complexation and precipitation. The recent trend of engineered biochar can enhance its surface properties, pH buffering capacity and presence of desired functional groups. This review focuses on the contribution of biochar in attaining sustainable development goals. Hence, it provides a thorough understanding of biochar's importance in enhancing soil productivity, bioremediation of environmental pollutants, carbon negative concretes, mitigation of climate change and generation of bioenergy that amplifies circular bioeconomy, and concomitantly facilitates the fulfilment of the United Nation Sustainable Development Goals. The application of biochar as seen is primarily targeting four important SDGs including clean water and sanitation (SGD6), affordable and clean energy (SDG7), responsible consumption and production (SDG12) and climate action (SDG13).
Lignocellulosic agricultural waste has the potential to be converted into several value-added products such as biofuels, oligosaccharides, organic acids, and other chemicals. Among oligosaccharides, xylooligosaccharides (XOS) are the major prebiotic compounds that can be produced from lignocellulosic waste through biocatalysis using microbial enzymes. XOS are highly regarded in the food and pharmaceutical sectors for their extensive health-boosting properties. Owing to the high demand for XOS, a lot of research is underway to develop technologies and bioprocesses for their sustainable and clean production. Conventional methods used for the production of XOS, such as autohydrolysis and chemical hydrolysis, are less sustainable and non-eco-friendly processes. Moreover, the quality of final product obtained using conventional methods is compromised. Bioconversion of lignocellulosic biomass using enzymatic hydrolysis and microbial fermentation to produce XOS is a favorable alternative to overcome this problem. This review highlights various factors that influence the sustainability and eco-friendly nature of the XOS production bioprocess. Optimizing the process parameters using different statistical tools may pave the way towards economical production of XOS with minimal use of resources. Moreover, the present review discusses about the lignocellulosic biorefinery that is involved in the conversion of agricultural wastes to several value-added products, which makes the bioprocess more economically sustainable. Collectively, modern technologies, including protein engineering, cell surface engineering, and metagenomics, are useful for the efficient bioconversion of lignocellulosic biomass to value-added products.
Hydrothermal pretreatment (HTP) (Hot water extraction (HWE) and steam pretreatment) and pyrolysis have the potential to liquefy lignocellulosic biomass. HTP produces hydrolysate, consisting mainly of solubilized hemicellulose, while pyrolysis produces aqueous pyrolysis liquid (APL). The liquid products, either as main products or by-product, can be used as anaerobic digestion (AD) feeds, overcoming shortcomings of solid-state AD (SS AD). This paper reviews HWE, steam pretreatment, and pyrolysis pretreatment methods used to liquefy lignocellulosic biomass, AD of liquefied products, effects of inhibition from intermediate by-products such as furan and phenolic compounds, and pretreatment tuning to increase methane yield. HTP, focusing on methane production, produces less inhibitory compounds when carried out at moderate temperatures. APL is a challenging feed for AD due to its complexity, including various inhibitory substances. Pre-treatment of biomass before pyrolysis, adaptation of microorganism to inhibitors, and additives, such as biochar, may help the AD cultures cope with inhibitors in APL.
Liquid hot water pretreatment modifies the physiochemical features of plant cell walls, including cell wall chemistry and composition, as well as cellulose and lignin ultrastuctures. This study was designed to assess how the presence of insoluble lignin, lignin monomer composition, and the macromolecular traits of deconstructed cellulose influence the content of glucose, xylose and total saccharides within solids during liquid hot water pretreatment of hybrid poplar wood. Hydrothermal pretreatments at 180 degrees C for both 5 and 10 min were found to be the most effective conditions to achieve maximum glucose content. Under these pretreatment conditions, it was possible to achieve a more than 50\% decrease in xylose content due to the solubilization of hemicelluloses, a low lignin content, and severe drops in the macromolecular traits of cellulose such as number-average molecular weight, weight-average molecular weight, degree of polymerization and polydispersity index. A continuous increase in the severity of the hydrothermal pretreatment resulted in a decrease in glucose content, an increase in insoluble lignin content, and an ongoing scission of cellulose chains. The amounts of glucose, xylose and total saccharides within solids were negatively influenced by the insoluble lignin content and the syringyl-to-guaiacyl ratio in lignin, but at the same time positively correlated with the cellulose degree of polymerization, weight average molecular weight and hydrogen bond intensity. Four groups of compact clusters of hydrothermal pretreatment conditions were identified in a multivariate wood trait analysis. (C) 2016 Elsevier B.V. All rights reserved.
The sustainable conversion of biomass into biofuels, chemicals and biomaterials has gained increasing attention to ensure the well-being of present and future generations. Among the different technologies available to date for the valorisation of biomass, microwave-assisted hydrothermal conversion has recently appeared as a state-of-the-art technology, capable of furnishing a wide range of reaction products for the energy, pharmaceutical and chemistry sectors. This emerging technology combines the inherent benefits of microwave heating and the sustainable features of biomass hydrothermal valorisation. Herein, for the first time, this critical review summarises and analyses all the work conducted to date on the use of microwave-assisted hydrothermal processes (including microwave-assisted carbonisation, liquefaction and treatment/hydrolysis) for the conversion of biomass into hydrochar, bio-crude (bio-oil) and valuable chemicals. In particular, this work has put together vital information addressing the influences of the reaction conditions (temperature, time, amount and type of catalyst, biomass loading and type, and microwave power) on the yields and key properties of the reaction products. The relationships between these processing parameters and the chemical transformations involved in the processes (hydrolysis, dehydration, decarboxylation, condensation and re-polymerisation) have been described in detail, and reliable comparisons have also been established between microwave-assisted and conventional hydrothermal technologies when data were available. As a result, this critical review collects essential information on the use of this cutting-edge, recently appeared microwave-assisted hydrothermal technology, and paves the way for its expansion and future development and commercialisation.
Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate's application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulose crystallinity, which inhibit the digestibility of the biomass for cellulose extraction. This situation offers both challenges and promises for the biomass biorefinery development to utilize the cellulose from lignocellulosic biomass. Thus, multistep biorefinery processes are necessary to ensure the deconstruction of noncellulosic content in lignocellulosic biomass, while maintaining cellulose product for further hydrolysis into nanocellulose material. In this review, we discuss the molecular structure basis for biomass recalcitrance, reengineering process of lignocellulosic biomass into nanocellulose via chemical, and novel catalytic approaches. Furthermore, review on catalyst design to overcome key barriers regarding the natural resistance of biomass will be presented herein.
The establishment of an efficient and feasible biorefinery model depends on, among other factors, particularly the selection of the most appropriate microorganism. Mucor circinelloides is a dimorphic fungus species able to produce a wide variety of hydrolytic enzymes, lipids prone to biodiesel production, carotenoids, ethanol, and biomass with significant nutritional value. M. circinelloides also has been selected as a model species for genetic modification by being the first filamentous oleaginous species to have its genome fully characterized, as well as being a species characterized as a potential bioremediation agent. Considering the potential of replacing several nonrenewable feedstocks is widely dependent on fossil fuels, the exploitation of microbial processes and products is a desirable solution for promoting a green and sustainable future. Here, we introduce and thoroughly describe the recent and critical applications of this remarkable fungus within the context of developing a fungal-based biorefinery.
CoFe2O4/activated carbon composite (CoFe2O4/AC) was prepared by a facile one-step low-temperature refluxing route. The obtained material was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area method and vibrating sample magnetometer techniques, respectively. The composite was tested as an adsorbent for the removal of gentian violet (GV). The adsorption process was investigated as the functions of ionic strength, temperature, solution pH, adsorbent dosage, contact time and initial GV concentration. The equilibrium adsorption data fitted well to the Langmuir model and the maximum adsorption capacity was found to be 184.2 mg g(-1) at 303 K. The remarkable adsorption capacity of GV onto CoFe2O4/AC was attributed to strong pi-pi interaction and weak electrostatic attraction between GV and CoFe2O4/AC. The thermodynamic analysis suggested that the adsorption of GV on CoFe2O4/AC was a spontaneous, physical and endothermic process. The adsorption processes could be described by the pseudo-second-order kinetic model. The whole adsorption process was jointly controlled by external mass transfer and intraparticle diffusion. Magnetic CoFe2O4/AC with adsorbed GV could be regenerated using acidic ethanol solution and was separable from liquid media using a magnetic field.
As a clean and efficient method of lignocellulosic biomass separation, organic acid pretreatment has attracted extensive research. Hemicellulose or lignin is selectively isolated and the cellulose structure is preserved. Effective fractionation of lignocellulosic biomass is achieved. The separation characteristics of hemicellulose or lignin by different organic acids were summarized. The organic acids of hemicellulose were separated into hydrogen ionized, autocatalytic and alpha-hydroxy acids according to the separation mechanism. The separation of lignin depends on the dissolution mechanism and spatial effect of organic acids. In addition, the challenges and prospects of organic acid pretreatment were analyzed. The separation of hemicellulose and enzymatic hydrolysis of cellulose were significantly affected by the polycondensation of lignin, which is effectively inhibited by the addition of green additives such as ketones or alcohols. Lignin separation was improved by developing a deep eutectic solvent treatment based on organic acid pretreatment. This work provides support for efficient cleaning of carbohydrate polymers and lignin to promote global carbon neutrality.
From year to year, mankind is struggling with an increasing climate crisis. Constant climate change is related to human activities. The global dependence on non-renewable fossil fuels to meet our current energy needs cannot be sustained longer in the face of depleting fuel reserves. Particular attention should be paid to biofuels produced from lignocellulosic biomass, which is a waste product from the forestry, paper and agricultural industries, or a product derived from energy crops, intended for biofuel purposes. A problem that arises when using lignocellulosic biomass is the limited availability of fermentable sugars due to its complicated structure. For this reason, various methods of pretreatment of the raw material are used. The aim of the pretreatment is to increase the availability of cellulose for hydrolytic enzymes and to separate the main fractions of the lignocellulosic material, mainly the lignin molecule. After pretreatment and hydrolysis, the monomeric sugars are further processed into ethanol through the fermentation process. The last stages in biotechnological lignocellulose conversion are the distillation and dehydration process to obtain pure biofuel. This work is a review of the literature on second-generation biofuels produced from lignocellulosic biomass. Issues ranging from various types of raw materials, methods of its pretreatment, enzymatic hydrolysis, fermentation with the participation of various microorganisms, to various methods of dehydration of the obtained bioethanol were discussed.
The shell surrounding fruits of the jatoba-do-cerrado tree, in its natural state, was modified by the addition of HNO3 and NaOH and used as an adsorbent in the removal of Cu(II) and Ni(II) from aqueous solutions. The untreated (JIN) and chemically modified (JCT) fruit shell samples were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray diffraction. Their efficiency as adsorbents in the removal of Cu(II) and Ni(II) ions from aqueous solutions was studied under different conditions of pH (2-9) and it was observed that the optimal pH for Cu (II) adsorption was 5.5 and for Ni (II) it was 6.0. The adsorption isotherms were obtained at different temperatures (298, 308, 318 K) and the q(max) values ranged from 33.96 to 41.00 mg g(-1). The adsorbents presented higher selectivity toward Cu ions (II). The thermodynamic analysis results suggest that the adsorption process studied is of a physical nature. Supported by quantum mechanical calculations, the interaction sites of the ion-cellulose and ion-lignin complexes were identified, evidencing the central role of water molecules in stabilization of the complexes. The experimental and theorical results indicate that JIN and JCT have good potential for the adsorption of Cu(II) and Ni(II) ions and are thus promising materials for the removal of other metal ions in aqueous systems.
Resource recycling of millions of solid waste is a worldwide problem. Because the element is the basic unit of all wastes, the essence of wastes recycling is to realize cycle of elements in waste. In this paper, a new concept of element cycle in waste is proposed. Under the guidance of the element cycle, various wastes have a common connection point. The concept is clarified by a case of C, H, Cl, and In element cycle from waste poly(vinyl chloride) (PVC) plastic and liquid crystal display (LCD) panels. In this paper, a vacuum pyrolysis of waste PVC was proposed to recycle indium in LCD and simultaneously prepare a carbon coating. Cl in PVC, combined with In in LCD, was mainly regenerated in the form of InCl3. Meantime, C and H in PVC were reused to prepare a carbon coating and energy products such as pyrolysis oil and gas. The recycling system means to change two types of waste into resources by their own element characteristics. Under optimized conditions, the recovery rate of indium exceeded 98\%. Meantime, with increasing temperature, the microstructure of carbon coating is gradually clear. The formation mechanism of the carbon coating was presented in detail. This study is meaningful for the sustainable development of resources recycling in waste.
Solid-state fermentation (SSF) is a three-phase heterogeneous process, comprising solid, liquid and gaseous phases, which offers potential benefits for the microbial cultivation for bioprocesses and products development. Over the last two decades, SSF has gained significant attention for the development of industrial bioprocesses, particularly due to lower energy requirement associated with higher product yields and less wastewater production with lesser risk of bacterial contamination. In addition, it is eco-friendly, as mostly utilizes solid agro-industrial wastes (resides) as the substrate (source of carbon). This article aims to present and analyze the current development on SSF taken place mainly during the last five years, linking the developments with earlier two papers published in this journal in 2003 (Pandey, 2003 {[
Recent developments in the use of activated carbons (ACs) of various geneses for wastewater treatment to remove copper, nickel, cadmium, and lead ions, which most frequently occur in industrial and municipal wastewaters, are summarized.
The rising activities of global agriculture and forestry industries are producing huge amounts of lignocellulosic waste, which needs to be well recycled. The management of this waste involves environmental, social, economic and political challenges. Lignocellulosics have been commonly used for construction materials and energy production, thus achieving positive social and environmental impacts. Lignocellulosics represent also a promising feedstock for the production of carriers for enzyme and cell immobilization. Immobilization is a technique in which the biocatalyst is fixed on the surface of an insoluble matrix, allowing to recover the biocatalyst after reaction. The support must have specific characteristics such as inertness, physical strength, stability, renewability and low cost. These characteristics are fulfilled by lignocellulosic materials. Here, we review the applications of lignocellulosic biomass for fermentation, remediation of contaminated water and soil, synthesis of solvents and fine chemicals, juices clarification, and production of fructooligosaccharides. Recycling lignocellulosic waste for the immobilization of enzymes and cells allow to reduce environmental issues. Processes using immobilized cells and enzymes give high rates of solvent productivity, of 1.44-1.67 g/Lh, activity retention, around 90\%, and stability, above five cycles of reaction.
Microbial biosurfactants are sustainable alternatives for synthetic counterparts, and display high biodegradability, environmental compatibility, and high selectivity. While previous reports have focussed on production yield, little attention has been paid on downstream processing of biosurfactants, a critical step that controls quality. Here we review methods for biosurfactant downstream processing with focus on glycolipids and lipopeptidesglycolipids and lipopeptides. Solvent extraction, foam fractionation, and sweep floc coagulation allow to reach a purity of 55-70\%. While distillation can be implemented prematurely, methods like ultrafiltration and chromatography are used as final processing to recover 90-95\% of biosurfactant with 78-95\% of purity. We present the cheapest and most efficient downstream techniques for industries to achieve acceptable product quality. This paper puts forth the environmental applications of biosurfactants. We review applications in treating hydrophobic organic pollutants and heavy metals in soils and water. The removal efficiency of biosurfactants reaches 96\%. Biosurfactants in the detergent industry, microbial enhanced oil recovery, and soil washing are also discussed.
Dark fermentative bio-hydrogen production is not commercially exploited due to several factors hindering its production, making the process unfeasible on large scale. This study provided an in-depth and critical review of different factors of the dark fermentation process namely H-2-consumers and lactic acid bacteria in mixed microflora, light and heavy metal ions, furan derivatives and phenolic compounds, ammonia and H-2 concentrations and soluble metabolites viz. acetic acid, ethanol, propionic acid and butyric acid that may negatively affect H-2 production. For each of the inhibitors, the mechanism behind process inhibition was explained while strategies for reducing inhibition were outlined. Among the different inhibitors studied, furan derivatives and phenolic compounds suppressed biohydrogen production to a larger extent while the most common strategies reviewed for reducing inhibition included inoculum pre-treatment for suppressing H-2-consumers and dilution of reactor contents for decreasing inhibitor concentrations. Although these options are encouraging on small scale, the economic and technical feasibilities of implementing these strategies on larger scale require further investigation. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Lignocellulosic biomass (LB) is an abundant and renewable resource from plants mainly composed of polysaccharides (cellulose and hemicelluloses) and an aromatic polymer (lignin). LB has a high potential as an alternative to fossil resources to produce second-generation biofuels and biosourced chemicals and materials without compromising global food security. One of the major limitations to LB valorisation is its recalcitrance to enzymatic hydrolysis caused by the heterogeneous multi-scale structure of plant cell walls. Factors affecting LB recalcitrance are strongly interconnected and difficult to dissociate. They can be divided into structural factors (cellulose specific surface area, cellulose crystallinity, degree of polymerization, pore size and volume) and chemical factors (composition and content in lignin, hemicelluloses, acetyl groups). Goal of this review is to propose an up-to-date survey of the relative impact of chemical and structural factors on biomass recalcitrance and of the most advanced techniques to evaluate these factors. Also, recent spectral and water-related measurements accurately predicting hydrolysis are presented. Overall, combination of relevant factors and specific measurements gathering simultaneously structural and chemical information should help to develop robust and efficient LB conversion processes into bioproducts.
The present study systematically investigated the combustion characteristics of spent mushroom substrate (SMS) using TG-MS (thermogravimetric/mass spectrometry) and TG-FTIR (thermogravimetric/Fourier transform infrared spectrometry) under five heating rates. The physicochemical characteristics and combustion index pointed to SMS as a promising biofuel for power generation. The high correlation coefficient of the fitting plots and similar activation energy calculated by various methods indicated that four suitable iso-conversional methods were used. The activation energy varied from 130.06 to 192.95 kJ/mol with a mean value of 171.49 kJ/ mol using Flynn-Wall-Ozawa and decreased with the increased conversion degree. The most common emissions peaked at the range of 200-400 degrees C corresponding to volatile combustion stage, except for CO2, NO2 and NO. The peak CO2 emission occurred at 439.11 degrees C mainly due to the combustion of fixed carbon.
The impact of water pollution has led to the search for cost-effective and environmentally friendly treatment processes to alleviate the associated environmental hazards. Adsorption is identified as an advanced treatment technology that offers simplicity and cheap alternatives to water treatment technologies when low-cost adsorbents such as industrial by-products, waste, and agricultural waste are utilized. The utilization of these materials as low-cost adsorbents for the treatment of drinking water will bring them some value. Several practices have been done to improve the removal efficiencies of the low-cost adsorbents in order to achieve WHO standards of drinking water quality. The paper highlights some of the synthesis routes employed for the modification of low-cost adsorbents. This updated review provides information on the different applications of low-cost adsorbents in removing pollutants and their adsorption capacities in an attempt to deploy the recent sustainable low-cost adsorbents with high removal efficiencies for water treatment. Future research should focus on the fabrication of hybrid low-cost adsorbents with multifunctional and antimicrobial properties. In addition, life cycle assessment (LCA) should be conducted to reveal the environmental burdens associated with the modification of the low-cost adsorbent to improve their removal efficiencies.
In recent years, with the global increase in industrialization, there has been a significant increase in the amount of toxic pollutants such as heavy metals being released into water bodies. Adsorption is considered as one of the most attractive methods due to its high efficiency and ability to remove heavy metals even at low concentration. Agricultural wastes-based biosorbents have attracted great interest due to their capability to effectively remove heavy metals from wastewater. Chemical modifications on biosorbents can significantly improve the biosorption capacities and the longevity of the biosorbents. Most of the adsorption studies followed the Langmuir and Freundlich adsorption isotherm models. The pseudo-second-order kinetic model best fitted most of the adsorption kinetic studies. Moreover, ion exchange, electrostatic attraction and chelation were the governing adsorption mechanisms in most of the studies. The adsorption process was usually spontaneous and endothermic in nature. The regeneration of biosorbents was most effective when acids were used as eluents and this had allowed some biosorbents to be reused efficiently up to 10 times. To elucidate a practical perspective, analysis on column studies, adsorption performance using industrial wastewater, and cost analysis had been conducted. Cost analysis proved that agricultural wastes-based biosorbents are cheaper than traditional adsorbents such as activated carbon.
Lignin is the second most abundant biorenewable polymers only next to cellulose and is ubiquitous in various plant foods. In food industry, lignin often presented as a major component of by-products from plant foods. In the last decade, the food and nutritional interests of lignin attracted more and more attentions and great progresses have been accomplished. In the present review, the structure, physicochemical properties, dietary occurrence and preparation methods of lignin from food resources were summarized. Then, the versatile activities of food lignin were introduced under the subtitles of antioxidant, antimicrobial, antiviral, antidiabetic and other activities. Finally, the potential applications of food lignin were proposed as a food bioactive ingredient, an improver of food package films and a novel material in fabricating drug delivery vehicles and contaminant passivators. Hopefully, this review could bring new insights in exploiting lignin from nutrition- and food-directed views.
Microbial production of organic acids has become a fast-moving field due to the increasing role of these compounds as platform chemicals. In recent years, the portfolio of specialty fermentation-derived carboxylic acids has increased considerably, including the production of glyceric, glucaric, succinic, butyric, xylonic, fumaric, malic, itaconic, lactobionic, propionic and adipic acid through innovative fermentation strategies. This review summarizes recent trends in the use of novel microbial platforms as well as renewable and waste materials for efficient and cost-effective bio-based production of emerging high-value organic acids. Advances in the development of robust and efficient microbial bioprocesses for producing carboxylic acids from low-cost feedstocks are also discussed. The industrial market scenario is also reviewed, including the latest information on the stage of development for producing these emerging bio-products via large-scale fermentation.
Present study emphasis environmental concern of agro-waste materials and approaches for their sustainable utilization in wastewater treatment for environmental safety and waste management. This paper also addresses the environmental issues by identifying various categories of food waste, its consumption, amount of waste generated, and methods to reuse them properly. Discharge of Agro waste from agricultural and food processing industries leads to a problem of solid waste disposal and related environmental issues for this a lot of research has been conducted to use adsorbents as a treatment method for organic and inorganic pollutants. Utilizing agro-waste and bio-based material as adsorbents for removing contaminants from wastewater may be a sustainable option for environmental management and safety. Therefore, this paper highlights the performance of adsorbents based on agro-based materials (such as banana, citrus, apple, grape, and mango), vegetable waste (such as potato, tomato, etc.) for effective wastewater treatment, anddeveloping sustainable technology for environmental and health safety. Copyright@2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the Sustainable Materials and Practices for Built Environment.
The global impetus to produce alternatives for the petroleum-based fuels and value-added chemicals in order to reduce greenhouse gases is currently emphasizing stringent need on the industries to diversify and valorize byproducts. This further aims at the valorization of agroindustrial by-product into furfural. A thorough investigation of research advances particularly, the pretreatment of biomass, a pertinent reaction mechanism in furfural production, separation of furfural and the various used catalysts were explored in the current review. The biomass, which contains fiber, lignin, pentosans, and pith, can be converted into furfural by the application of suitable chemical, biochemical and microbial methods. Dilute acid, alkali and hydrothermal pretreatment methods for hemicellulose separation from the biomass matrix were discussed in detail. Studies on the development of an effective and stable catalyst to overcome the limitation of the existing commercial processes were also reviewed. The strategies including the steam stripping, nitrogen stripping, supercritical carbon dioxide extraction, mono- and biphasic solvent extractions were investigated in this study, as a way forward towards the removal of furfural from the reaction medium, thereby assisting in the avoidance of the product degradation. {[
Butanol can be produced from renewable sources via the acetone-butanol-ethanol (ABE) fermentation route to create biobutanol or from fossil fuel to create petrobutanol. Despite the similar chemical properties of these two forms of butanol, the market penetration of biobutanol is still hindered due to its higher production costs compared to those for petrobutanol. This review article traces the history of the butanol industry and discusses recent advances in butanol production by ABE fermentation, with several novel approaches being highlighted. These approaches include searching for abundant and inexpensive substrates and optimising upstream and downstream processes. As butanol production by ABE fermentation consists of several critical stages, this review article divides the whole process into five significant steps: (1) feedstock selection, (2) upstream, (3) midstream, (4) downstream and (5) final products. Recent progress involving all stages along with their challenges and potential research routes are summarised. Recent progresses in the direct use of ABE as a biofuel are also reviewed in brief. Low butanol yield and end-product toxicity remain the major drawbacks of a typical butanol production by ABE fermentation. For successful biobutanol production, a number of critical issues should be considered. These include the development of clostridial and non-clostridial strains as well as innovative in-situ recovery methods integrated with the ABE fermentation process. Finally, future research direction of butanol production by ABE fermentation is presented in the last section of this article.
This paper provides an updated and comprehensive review on the catalytic upgrading of biomass-derived pyrolysis vapours over metal-modified HZSM-5 catalyst into bio-aromatic hydrocarbons. The catalytic upgrading of biomass pyrolysis vapours seems to be a promising technology in generating gasoline-type bio-aromatic hydrocarbons, i.e. benzene, toluene and xylene (BTX). Biomass-derived raw pyrolysis oil has high oxygenated compounds that deteriorate pyrolysis oil properties and limits its applications. Metal modification of hydrogen exchanged Zeolite Socony Mobil Five (HZSM-5) catalyst has gained attention in a biomass pyrolysis research area due to the beneficial effects on upgrading the oxygenated pyrolysis vapours into BTX-enriched pyrolysis oils. The influence of metals (alkali and alkaline earth metals, transition metals and rare earth metals) as bi-functional or multifunctional activity on HZSM-5 catalyst during pyrolysis has been addressed. The effect of reaction temperature, the type of metals, metal contents, the silica-to-alumina ratio of catalyst and the catalyst-to-biomass ratio are critically discussed for maximum production of monocyclic aromatic hydrocarbons during the upgrading of pyrolysis vapours. Finally, concluding remarks on metal-modified zeolite catalyst and future recommendation in upgrading biomass pyrolysis vapours are presented.
In recent years, utilization of renewable sources for biofuel production is gaining popularity due to growing greenhouse gas (GHG) emissions which causes global warming. There has been a great effort in exploring alternative feedstock for bioethanol production. In this context, the production of third-generation bioethanol from macroalgae has emerged as an alternative feedstock to food crop-based starch and lignocellulosic biomass. This is mainly due to the fast growth rate of macroalgae, no competition with agricultural land, high carbohydrate content and relatively simple processing steps compared to lignocellulosic biomass. This review paper provides an insight of recent innovative approaches for macroalgae bioethanol production, including conventional and advanced hydrolysis process to produce fermentable sugar, various fermentation technologies, economic analysis and life cycle assessment. With the current technology maturity, efficient utilization of macroalgae as sustainable source for bioethanol and other value-added chemicals production could be achieved in the near future. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.
Catalytic and non-catalytic co-pyrolysis of Corn Stalk (CS) and Polystyrene (PS) was conducted in a fixed bed reactor at 500 degrees C to evaluate the effect of feedstock blend ratio, catalyst to feedstock ratio (CFR) and mode of catalyst addition. In first phase, CS and PS were co-pyrolyzed in multiple blend ratios (1:0, 1:3, 1:1, 3:1, 0:1) without catalyst application. Increasing PS in blend increased oil yield, with a maximum synergistic value of 5.75 observed at CS:PS ratio of 1:3. In the second phase, comparison between in-situ and ex-situ use of HZSM-5 catalyst at five different CFR (1:10, 1:4, 1:2, 3:4 and 1:1) was explored. The insitu mode yielded more liquid oil (maximum 66.5\% at CFR 1:4) with higher (80.1\% at CFR 1:2) mono aromatic hydrocarbons (MAH) and less (6.5\% at CFR 1:10) poly aromatic hydrocarbons (PAH) and acids (4.6\% at CFR 1:1). However, increasing CFR in twain modes decreased MAH and oxygenates and increased PAH and acids. Maximum aromatics selectivity to BTEX (similar to 100\%) and negligible selectivity to styrene was noticed at ex-situ CFR of 1:1. Non-catalytic co-pyrolysis yielded maximum MAH (83\%). Further physical analysis of non-catalytic co-pyrolysis oil showed properties of liquid oil close to conventional fossil fuels. (C) 2019 Elsevier Ltd. All rights reserved.
Coconut palm(Cocos nucifera) is an important commercial crop in many tropical countries, but its industry generates large amounts of residue. One way to address this problem is to use this residue, coconut husk, to produce second-generation (2G) ethanol. The aim of this review is to describe the methods that have been used to produce bioethanol from coconut husk and to suggest ways to improve different steps of the process. The analysis performed in this review determined that alkaline pretreatment is the best choice for its delignification potential. It was also observed that although most reported studies use enzymes to perform hydrolysis, acid hydrolysis is a good alternative. Finally, ethanol production using different microorganisms and fermentation strategies is discussed and the possibility of obtaining other added-value products from coconut husk components by using a biorefinery scheme is addressed.
Lignocellulosic biomass is a plant dry matter that could be considered as a renewable carbon resource for the production of reducing sugar, which is an alternative building block for biofuels and chemicals. However, due to the recalcitrant nature of lignocellulosic biomass, researchers have focused their efforts on establishing cost-efficient pretreatments to reutilize the lignocellulose components within the biomass effectively. In this study, divalent (CuCl2) and trivalent (FeC1(3)) inorganic salts were used in the recovery of xylose from the stalks of oil palm fronds (OPF). Additionally, oxidizing agents such as hydrogen peroxide and sodium persulfate were tested for their effectiveness in improving inorganic salt pretreatment. By using inorganic salt alone, FeC13 outperformed CuCl2 in terms of xylose recovery, in which 75.5 and 59.3\% of xylose could be recovered from OPF using FeC13 and CuCl2, respectively. An incorporation of sodium persulfate with CuCl2 enabled a maximum xylose recovery up to 72.0\%, with no statistical difference as compared to using FeCI3 alone. The synergism between CuCl2 and sodium per sulfate was attributed to the formation of unstable Cu3+ ions, which acted as a trivalent salt. Characterization studies of the solid fraction before and after pretreatment also validated the delignification of OPF. Hence, the combination of CuCl2 and sodium persulfate was able to attain sugar yields which were comparable with other conventional pretreatments. (C) 2017 Elsevier Ltd. All rights reserved.
Lignin nanotubes (LNTs) synthesized from the aromatic plant cell wall polymer lignin in a sacrificial alumina membrane template have as useful features their flexibility, ease functionalization due to the availability of many functional groups, label-free detection by autofluorescence, and customizable optical properties. In this report we show that the physicochemical properties of LNTs can be varied over a wide range to match requirements for specific applications by using lignin with different subunit composition, a function of plant species and genotype, and by choosing the lignin isolation method (thioglycolic acid, phosphoric acid, sulfuric acid (Klason), sodium hydroxide lignin), which influences the size and reactivity of the lignin fragments. Cytotoxicity studies with human He La cells showed that concentrations of up to 90 mg/mL are tolerated, which is a 10-fold higher concentration than observed for single- or multiwalled carbon nanotubes (CNTs). Confocal microscopy imaging revealed that all LNT formulations enter He La cells without auxiliary agents and that LNTs made from NaOH-lignin penetrate the cell nucleus. We further show that DNA can adsorb to LNTs. Consequently, exposure of He La cells to LNTs coated with DNA encoding the green fluorescent protein (GFP) leads to transfection and expression of GFP. The highest transfection efficiency was obtained with LNTs made from NaOH-lignin due to a combination of high DNA binding capacity and DNA delivery directly into the nucleus. These combined features of LNTs make LNTs attractive as smart delivery vehicles of DNA without the cytotoxicity associated with CNTs or the immunogenicity of viral vectors.
Alternanthera philoxeroides, a notorious invasive aquatic weed, is a typical lignocellulosic feedstock for fermentative biohydrogen production. To improve the dark fermentation performance, steam-heated acid pretreatment and enzymolysis were employed to release reducing sugars from A. philoxeroides, and Enterobacter aerogenes ZJU1 mutagenized by Co-60-(gamma) irradiation was used as the inoculum. Dilute acid accompanied by steam heating significantly disrupted the fiber structures of A. philoxeroides. Scanning electron microscopic images revealed that many pores and fissures were generated in the surface of A. philoxeroides after pretreatment. X-ray diffraction and Fourier transform infrared spectroscopy analyses showed that the pretreatment facilitated the transformation of cellulose I to cellulose II in A. philoxeroides biomass, resulting in the increase of amorphous regions and the decrease of crystallinity. Under the optimum pretreatment condition (1.0 v/v\% H2SO4, 135 degrees C for 15 min), the reducing sugar yield reached 0.354 g/g A. philoxeroides, which was further increased to 0.575 g/g A. philoxeroides after enzymolysis. The biohydrogen yield increased by 59.9\% from 38.9 mL/g volatile solids (VS) of raw A. philoxeroides to 62.2 mL/gVS of the pretreated one. As compared to the wild strain, E. aerogenes ZJU1 contributed to an increase of 31.8\% in the biohydrogen yield from pretreated A. philoxeroides. Further optimization of bac teria suspensions significantly increased the maximum biohydrogen production rate from 1.42 to 4.64 mL/gVS/h, advanced the biohydrogen production peak, and resulted in an increase of 42.8\% in biohydrogen yield to 89.8 mL/gVS. (C) 2019 Elsevier B.V. All rights reserved.
Over the past few years, cellulose nanocrystals (CNCs), also known as nanocrystalline cellulose (NCCs), have received significant attention owing to their diverse spectrum of applications. CNCs are commonly considered in nanomedicine, the food industry, tissue engineering, energy and storage applications, paper and textile industry, polymeric composites, and bio-catalysis. Due to the versatility of CNCs and CNC-derived materials, there is increasing importance in characterizing their properties using spectroscopic techniques. These spectroscopic techniques include solid-state nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron (XPS) spectroscopy, and Raman spectroscopy. This review focuses on the characterization of CNCs and CNCs-derived materials using the aforementioned spectroscopic techniques. This review also discusses the background, experimental procedures, sample preparation, and spectral analysis methods used in these techniques.
Pyrolysis is one of the substantial thermal conversion technologies for high-value reutilization of biomass and organic solid waste (OSW). Adding some typical OSWs to biomass pyrolysis can achieve directional regulation of target products that are considered potential alternatives to fossil energy. Understanding copyrolysis behaviors is vital for the optimizing pyrolysis process to minimize environmental pollution and efficiently utilize biomass and OSW. However, there is no overall review on the copyrolysis of biomass and various OSWs. This paper reviews and discusses recent advances in the copyrolysis mechanism, thermal-chemical processes of some typical OSWs and biomass, and effects of chemical compositions of raw materials and pyrolysis parameters on thermal-chemical conversion behaviors, synergistic effect, and copyrolysis product characteristics. Recent reports show that the synergistic effect in copyrolysis effectively improves the quality of bio-oil and biochar. Moreover, adding OSW to biomass pyrolysis can promote the secondary reaction of pyrolysis intermediates. The reaction mechanism and relative numerical simulation work of copyrolysis are summarized. Finally, the current challenges to energy-and environment-oriented conversion of biomass and OSW are discussed, and perspectives for further developing the copyrolysis process are highlighted. This paper provides valuable information for optimizing sustainable copyrolysis processes of OSW and biomass and improving the efficiency and selectivity of recycled OSW.
The pretreatment and the enzymatic saccharification are the key steps in the extraction of fermentable sugars for further valorization of lignocellulosic biomass (LCB) to biofuels and value-added products via biochemical and/or chemical conversion routes. Due to low density and high-water absorption capacity of LCB, the large volume of water is required for its processing. Integration of pretreatment, saccharification, and co-fermentation has succeeded and well-reported in the literature. However, there are only few reports on extraction of fermentable sugars from LCB with high biomass loading (>10\% Total solids-TS) feasible to industrial reality. Furthermore, the development of enzymatic cocktails can overcome technology hurdles with high biomass loading. Hence, a better understanding of constraints involved in the development of technology with high biomass loading can result in an economical and efficient yield of fermentable sugars for the production of biofuels and bio-chemicals with viable titer, rate, and yield (TRY) at industrial scale. The present review aims to provide a critical assessment on the production of fermentable sugars from lignocelluloses with high solid biomass loading. The impact of inhibitors produced during both pretreatment and saccharification has been elucidated. Moreover, the limitations imposed by high solid loading on efficient mass transfer during saccharification process have been elaborated.
The development of a biobased environmentally sustainable economy will depend on the correct choices of options at several levels. This should include a proper choice of biomass, overcoming the bottlenecks of pretreatment processes, reduction in costs and increasing effectiveness of hydrolytic enzymes, use of genetic and metabolic engineering for increasing the yields of the biocatalysts involved, and addressing environmental, economic, and social sustainability simultaneously. High capital and operating costs, technical immaturity, and scale up challenges are the major road blocks to industrial biorefining processes. This review article highlights the factors that need to be taken into account in the selection and harvesting of lignocellulosic biomass for bioproducts valorization in a carbon neutral manner. Bioethanol production from lignocellulosic biomass is analyzed and alternative routes for the production of platform chemicals are recommended. The need for simultaneous Techno Economic Analysis (TEA) and Life Cycle Assessment (LCA) along with monetization of the environmental effects to make such processes competitive is stressed. Utilization of all three major components of biomass in a specific industry will be needed for profitable biorefining facilities using lignocellulosic residues. A comparison of scenarios in which the hemicellulose and lignin streams are used for the production of alternate co-products and energy along with the main C-6 sugar based product is emphasized.
Cellulases play a promising role in the bioconversion of renewable lignocellulosic biomass into fermentable sugars which are subsequently fermented to biofuels and other value-added chemicals. Besides biofuel industries, they are also in huge demand in textile, detergent, and paper and pulp industries. Low titres of cellulase production and processing are the main issues that contribute to high enzyme cost. The success of ethanol-based biorefinery depends on high production titres and the catalytic efficiency of cellulases functional at elevated temperatures with acid/alkali tolerance and the low cost. In view of their wider application in various industrial processes, stable cellulases that are active at elevated temperatures in the acidic-alkaline pH ranges, and organic solvents and salt tolerance would be useful. This review provides a recent update on the advances made in thermostable cellulases. Developments in their sources, characteristics and mechanisms are updated. Various methods such as rational design, directed evolution, synthetic \& system biology and immobilization techniques adopted in evolving cellulases with ameliorated thermostability and characteristics are also discussed. The wide range of applications of thermostable cellulases in various industrial sectors is described.
The recent strategies in preparation of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) were described. CNCs and CNFs are two types of nanocelluloses (NCs), and they possess various superior properties, such as large specific surface area, high tensile strength and stiffness, low density, and low thermal expansion coefficient. Due to various applications in biomedical engineering, food, sensor, packaging, and so on, there are many studies conducted on CNCs and CNFs. In this review, various methods of preparation of CNCs and CNFs are summarized, including mechanical, chemical, and biological methods. The methods of pretreatment of cellulose are described in view of the benefits to fibrillation.
In recent years, there have been emerging studies on developing different techniques to improve the properties of pyrolysis bio-oil. One of such techniques is the co-pyrolysis of biomass with hydrogen-rich feedstock of higher fuel qualities. Co-pyrolysis aims to decrease the water and oxygen contents, increase the calorific and heating values, and eliminate the corrosion and instability problems associated with their direct use in boilers and turbines for heat and power generation and as a transport fuel. Lignocellulosic and macroalgae biomass feedstocks are complementary based on their different compositions, and this combination has been employed in copyrolysis techniques. In this review, the biomass feedstock characteristics and their effects on thermal conversion into bio-oil were discussed. Due to the heterogeneous nature of the two biomass feedstocks, investigations of their co-pyrolysis behaviour and their reaction mechanisms in both catalytic and non-catalytic reactions were explored. The synergistic effect which is the key reason behind the improvement in the yield and quality of biooil obtained from the co-pyrolysis of these biomass feedstocks was also examined. The resulting bio-oils from the co-pyrolysis were comprehensively analyzed and are characterized by improved properties than the pyrolysis of lignocellulosic or macroalgae biomass alone. However, due to thermal degradation, the existence of high oxygenated compounds in this pyrolysis bio-oil is a challenge that needs to be overcome. Catalytic co-pyrolysis could be implemented for additional upgrading of the pyrolysis bio-oil as liquid fuel for several purposes. Finally, the main bottlenecks, key solutions and future directions for the study were provided.
Xylooligosaccharides (XOS) are one of the emerging oligomers exhibiting prebiotic activity. They are mainly produced by the hydrolysis of cheap and abundant lignocellulosic feedstocks. It has been demonstrated that the oligomers with low degree of polymerization (2-4) are more selective for the microbiota. Therefore, several attempts have been made to develop efficient processes for the production of such types of XOS by employing different strategies. Microbial xylanases possess a crucial role in these processes. They are highly specific biocatalysts that do not produce any undesirable byproducts during oligomer production. This review provides detailed information about the xylanases belonging to different glycoside hydrolase families with respect to their ability to produce XOS. The enzyme integrated methodologies for XOS production are described from a commercial perspective. The studies focusing on XOS production by xylanase enzymes from different microbial sources were summarized in a strain specific manner for the first time. The physicochemical and technological properties of XOS, their current applications, and market potential were presented.
This paper reports the progress of catalysts for improving the hydrocarbon compounds in bio-oil obtained from catalytic pyrolysis of biomass. In addition, the effects of the other operating conditions, such as temperature, type of biomass, heating rate, vapors residence time, carrier gas, and hydrogen donor on the yield and properties of bio-oil have been briefly explored. Temperature and catalysts type were found to have major impact on the bio-oil yield and quality. TGA-DTA analysis of biomass revealed that major biomasses pyrolysis zone for high bio-oil yield is in the range of 400-600 degrees C. Pilot, semi-pilot and large-scale units reported an average temperature of 500 degrees C for pyrolysis of biomass. The development of advanced catalysts such as zeolite-based catalysts, supported transition and noble metal catalysts, and metal oxide catalysts have been designed to remove the undesired compounds and to increase the hydrocarbon yield in bio-oil. Noble metal supported catalysts produced bio-oil with a low content of oxygenated compounds compared to non-noble metal catalysts; however, their cost and accessibility favor the utilization of non-noble metal supported catalysts.
AimsCurrently, there is no direct method for detecting Clostridium thermocellum in the insoluble medium. In this study, a quantitative real-time PCR assay was developed for the direct growth detection of C.thermocellum at the single-cell level in lignocellulosic biomasses. Methods and ResultsThe assay targeted the cipA gene and was able to distinguish C.thermocellum from other species with good reproducibility which quantitative detection limit was 10 cell equivalents (CE) per reaction. OD600-based counting and qPCR quantification of C.thermocellum cultured in soluble medium were compared and an excellent consistency was revealed, indicating the appropriateness of the developed qPCR method. Analysis based on yellow affinity substrate and fermentation products may incorrectly estimate its population. ConclusionsThe developed assay can serve as a specific, sensitive and reproducible method for the detection of C.thermocellum in lignocellulosic biomass at the single-cell level. Significance and Impact of the StudyWith the ability to rapidly detect C.thermocellum, this method will contribute substantially to the understanding of the lignocellulosic biomass degradation mechanism. Moreover, it can also be applied to detect C.thermocellum growth in certain co-culture system for the understanding of the metabolic interactions.
The present review explores fruit wastes as potential and low-cost substrates for economical production of cellulase enzymes. Being renewable, vast availability and having rich organic nutrient, these fruit wastes can be exploited to produce cellulase enzyme for various industrial applications. This review aimed to explore recent insight in sustainable production of microbial cellulolytic enzymes following solid state fermentation (SSF) wherein different types of fruit wastes as a potentially viable and alternative form of substrates have been uti-lized. In addition, detailed about the characteristics, mechanisms and market scenario of cellulase enzymes produced through a range of microbial species have been discussed. Further, impacts of different physico-chemical parameters on solid-state fermentation based enzyme production and scale up issues have also analyzed. Moreover, applications of cellulases to produce different types of biofuels have been evaluated while emphases are made on existing hindrances and the possible strategies to improve the enzyme production process using fruit wastes.
Biomass consists of predominantly a biochemical mixture of three major lignocellulosic components: hemicellulose, cellulose, and lignin. The amounts of these three major polymeric components in biomass affect the functioning of thermochemical processes and thus affecting the efficiency of the biomass-based energy plants. On the other hand, experimental procedures for the hemicellulose, cellulose, and lignin determination are expensive, time-consuming, and not commercially viable. Recently, researchers are developing computational methods to minimize experimental procedures. Artificial neural network (ANN), which is a subset of machine learning, can develop relationships between input-output for non-linear and complex datasets. In this paper, we reported the first comprehensive study on estimating hemicellulose, cellulose, and lignin fractions of biomass using proximate analysis results on as received basis with a machine learning method. The ANN model performed a satisfactory performance for all the major biochemical components with the determination coefficient R-2 > 0.96.
Activated carbon from lemon wood (AC) and ZnO nanoparticles loaded on activated carbon (ZnO-NP-AC) were prepared and their efficiency for effective acid yellow 199 (AY 199) removal under various operational conditions was investigated. The dependence of removal efficiency on variables such as AY 199 concentration, amount of adsorbent and contact time was optimized using response surface methodology and Design-Expert. ZnO nanoparticles and ZnO-NP-AC were studied using various techniques such as scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray analysis. The optimum pH was studied using one-at-a-time method to achieve maximum dye removal percentage. Small amounts of the proposed adsorbents (0.025 and 0.025g) were sufficient for successful removal of AY 199 in short times (4.0 and 4.0min) with high adsorption capacity (85.51 and 116.29mg g(-1) for AC and ZnO-NPs-AC, respectively). Fitting the empirical equilibrium data to several conventional isotherm models at optimum conditions indicated the appropriateness of the Langmuir model with high correlation coefficient (0.999 and 0.978 for AC and ZnO-NPs-AC, respectively) for representation and explanation of experimental data. Kinetics evaluation of experiments at various time intervals revealed that adsorption processes can be well predicted and fitted by pseudo-second-order and Elovich models. This study revealed that the combination of ZnO nanoparticles and AC following simple loading led to significant improvement in the removal process in short adsorption time which was enhanced by mixing the media via sonication.
Globally, the annual generation of industrial and agricultural by-products is exceeding a thousand million tons and forecasted to tremendously inflate in the future. The by-products are usually either landfilled or incinerated causing environmental impacts. Many waste products are effectively utilized in the development of eco-friendly concrete. This study targets the adoption of generated by-products as an alternative to cement in the production of self-compacting concrete (SCC) based on the existing literature. SCC is majorly composed of high cement content, aggregates, chemical admixtures, and water. On the other hand, the cement production emits high levels of carbon dioxide causing environmental hazards and could be reduced to a certain extent by implementing these by-products as cement blends. The by-products are examined for its suitability by the material characterization, physical and chemical properties to match the pozzolanic behavior. This paper reviews comprehensively on the effect of utilizing industrial and agricultural by-products on the workability, strength, permeability, and microstructural performance when blended with SCC. This study summarizes the advantages of utilizing by-products towards the production methodology of a more sustainable and environmentally friendly SCC.
Pretreatment of lignocellulosic biomass to overcome its intrinsic recalcitrant nature prior to the production of valuable chemicals has been studied for nearly 200 years. Research has targeted eco-friendly, economical and time-effective solutions, together with a simplified large-scale operational approach. Commonly used pretreatment methods, such as chemical, physico-chemical and biological techniques are still insufficient to meet optimal industrial production requirements in a sustainable way. Recently, advances in applied chemistry approaches conducted under extreme and non-classical conditions has led to possible commercial solutions in the marketplace (e.g. High hydrostatic pressure, High pressure homogenizer, Microwave, Ultrasound technologies). These new industrial technologies are promising candidates as sustainable green pretreatment solutions for lignocellulosic biomass utilization in a large scale biorefinery. This article reviews the application of selected emerging technologies such as ionizing and non-ionizing radiation, pulsed electrical field, ultrasound and high pressure as promising technologies in the valorization of lignocellulosic biomass.
Calcium-based stabilizer materials (CSMs) exhibit pozzolanic properties which improve the properties of clayey soils by hydration, cation exchange, flocculation, pozzolanic reaction, and carbonation. In this comprehensive review, comprising over past three decades from 1990 to 2019, a mechanistic literature of expansive soil stabilization by incorporating CSMs is presented by reviewing 183 published research articles. The advantages and disadvantages of CSMs as the ground stabilizing agent are succinctly presented, and the major outcomes of physicochemical effects on soil properties are discussed in detail. After blending with CSM, the main and interaction effects on soil properties with focus on chemical processes such as X-ray fluorescence, X-ray diffraction analyses, and microstructure interaction by using scanning electron microscopy and thermogravimetric analysis have been reviewed in light of findings of past researchers. This work will help geotechnical engineers to opt for suitable CSM in the field of geoenvironmental engineering in committing to sustainable construction of civil engineering structures over expansive soils.
Lignocellulose might become an important feedstock for the future development of the biobased economy. Although up to 75 \% of the lignocellulose dry weight consists of sugar, it is present in a polymerized state and cannot be used directly in most fermentation processes for the production of chemicals and fuels. Several methods have been developed to depolymerize the sugars present in lignocellulose, making the sugars available for fermentation. In this review, we describe five different pretreatment methods and their effect on the sugar and non-sugar fraction of lignocellulose. For several pretreatment methods and different types of lignocellulosic biomass, an overview is given of by-products formed. Most unwanted by-products present after pretreatment are dehydrated sugar monomers (furans), degraded lignin polymers (phenols) and small organic acids. Qualitative and quantitative effects of these by-products on fermentation processes have been studied. We conclude this review by giving an overview of techniques and methods to decrease inhibitory effects of unwanted by-products.
Biopolymer functionalization is perceived as an innovative approach to revolutionizing bio-catalyzed chemical transformations. Lignin, the chief natural source of polyphenols, has an aromatic structure with plenty of beneficial chemical groups. Accordingly, lignin can be functionalized, copolymerized, or recombined with different types of chemicals to produce highly efficient catalysts. Moreover, the stability and biodegradability of lignin make it an efficient bio-immobilizer for diverse metals (Pt, Pd, Ag, Cu, Co, Fe, etc.), which are known for their excellent catalytic performances. In addition, the solid nature of the lignin-derived catalysts has excellent advantages in terms of simple catalyst recovery and reuse over consecutive cycles with high stability. The present work compiles the newly adopted approaches to valorize lignin in the field of catalysis. Lignin-derived acid and base catalysts, lignin metal-free catalysts, and lignin-supported metal catalysts have demonstrated the full potential of lignin in hydrolysis, esterification, oxidation, condensation, hydration, and multicomponent reactions. The synthesis methods, properties, and catalytic capacity of lignin-based catalysts were assessed and contrasted with conventional catalysts. Attractively, the inclusion of lignin in catalysis appeared as a novel upgrading strategy that offers eco-friendly and profitable materials, leading to simple and green chemical synthesis, as well as a revolutionary shift in the industrialization of biomass-derived materials generally, and functionalized lignin-based catalysts specifically.
The most advantageous renewable energy source which is still being explored for the source of renewable energy is biodiesel. But the major hindrance factor in the part of commercialization is the raw material cost under large scale various. Microalgae derived biofuels have drawn compelling interest as a sustainable and potential fossil fuel. The cellular mechanism of microalgae has been found to alter by the effect of some biotic and abiotic factors. Above all, those environmental parameters and production conditions can also act as a critical factor in altering the component quantity and quality of the biodiesel produced by microalgae. The lipids are accumulated inside the oleaginous microbial cells in the form of lipid droplet, and hence the cell disruption is essential for lipid extraction to enhance the yield. Huge varieties of physicochemical and mechanical pretreatment methods are available to facilitate extraction by effective cell membrane degeneration of oleaginous microbes. The present review is to exploit the probable magnitude and advantages of abiotic factors towards microalgal growth and biodiesel production. Additionally, this study tried to evaluate the possible certainties of the microalgal pretreatment processes in lipid accumulation.
In this study, a novel pretreatment for spent coffee waste (SCW) has been proposed which combines two techniques viz. atmospheric air plasma and FeCl3 to create a superior pretreatment that involves Fenton chemistry. The pretreatment was optimised employing Taguchi Design of Experiments, and five parameters were taken into consideration viz. biomass loading, FeCl3 concentration, H2SO4 concentration, plasma discharge voltage and treatment time. The composition analysis of the pretreated SCW revealed substantial amounts of lignin removal, with a maximum for process conditions of 70 kV for 2 min in an acidic environment containing 1\% H2SO4. FTIR, XRD and DSC were performed to characterise the samples. The pretreated SCW after enzymatic hydrolysis yielded 0.496 g of reducing sugar/g of SCW. The hydrolysate was subjected to fermentation by S. cerevisiae and led to the production of 18.642 g/l of ethanol with a fermentation efficiency of 74\%, which was a two fold increase in yield compared to the control. (C) 2017 Elsevier Ltd. All rights reserved.
Bioethanol fuel obtained from biomass and bioenergy crops has been proclaimed as one of the feasible alternative to gasoline fuel, as it is considered to be clean, renewable and green. In this review, the bioethanol production techniques from different lignocellulosic biomass, and its potential ethanol yield are studied. Moreover, this paper has reviewed the effects of bioethanol fuel blends on spark ignition engine combustion characteristics (i.e. cylinder pressure, cylinder temperature, flame speed, combustion efficiency, combustion duration, heat release rate, knocking and cold start); engine performance parameters (i.e. torque, brake power, brake specific fuel consumption, brake mean effective pressure, brake thermal efficiency and volumetric efficiency); and emission characteristics (i.e. carbon monoxide, oxides of nitrogen, carbon dioxide, unburned hydrocarbon and other unregulated emissions). Recently, many researchers produced bioethanol from herbaceous, industrial and municipal solid wastes (MSW) instead of agriculture and woody biomass. Most of the engine test results showed a remarkable improvement in engine performance and enhanced combustion characteristics for bioethanol fuel. In addition, the carbon monoxide and unburned hydrocarbon emissions decreased. Conversely, carbon dioxide and oxides of nitrogen emissions were not significantly reduced. Furthermore, there was no significant reduction of unregulated emissions, such as aromatics, acetaldehyde, and carbonyls. (C) 2015 Published by Elsevier Ltd.
In recent years, visualization and characterization of lignocellulose at different scales elucidate the modifications of its ultrastructural and chemical features during hydrothermal pretreatment which include degradation and dissolving of hemicelluloses, swelling and partial hydrolysis of cellulose, melting and redepositing a part of lignin in the surface. As a result, cell walls are swollen, deformed and de-laminated from the adjacent layer, lead to a range of revealed droplets that appear on and within cell walls. Moreover, the certain extent morphological changes significantly promote the downstream processing steps, especially for enzymatic hydrolysis and anaerobic fermentation to bioethanol by increasing the contact area with enzymes. However, the formation of pseudo-lignin hinders the accessibility of cellulase to cellulose, which decreases the efficiency of enzymatic hydrolysis. This review is intended to bridge the gap between the microstructure studies and value-added applications of lignocellulose while inspiring more research prospects to enhance the hydrothermal pretreatment process.
In this study, Leucaena leucocephala wood was pretreated with aqueous glycerol having H2SO4 as the catalyst. Response surface methodology (RSM) and artificial neural network (ANN) were used to optimize the process parameters, catalyst concentration (1-3\%), duration (120-300 min) and temperature (100-150 degrees C). ANN gave more accurate predictions for total reducing sugar yield than RSM. ANN also had lower values for error functions. Severity index (SI) was calculated based on the temperature, duration and catalyst concentration. Increase in SI from 0.21 {*
One-third of food produced for human consumption is lost as waste along the food supply chain. The food industry wastes contain carbohydrates, proteins, lipids, and lignocellulosic substances such as cellulose, hemicellulose, and lignin. These wastes are produced in large quantities worldwide and cause serious environmental problems. Due to the high concentration in organic and nutrient substances, food industry wastes are used for bioethanol production by microorganisms through various fermentation systems. The conversion of a lignocellulosic substance into bioethanol includes three steps: pretreatment, enzymatic hydrolysis, and fermentation. The problems concerning bioethanol production from food industry wastes are related to handling of biomass and application of pretreatment methods in order to improve the conversion of lignocellulosic materials into fermentable sugars. This review provides detailed overview and current knowledge on the pretreatment methods of lignocellulosic substances such as chemical (acid or alkaline, organic solvent), physical (milling, pyrolysis, microwave oven irradiation), physicochemical (steam explosion, hydrothermal processes, ammonia fiber explosion, CO2 explosion), and biological (fungi, bacteria). Pretreatment is followed by enzymatic hydrolysis with a mixture of suitable enzymes (mainly cellulase, beta-glucosidase, pectinase) at 50 degrees C for 48 or 72 h. The production of bioethanol from food industry wastes is enhanced by enzymatic hydrolysis of the total polysaccharides into metabolizable sugars. The conversion of wastes from the food industry to the second generation ethanol is discussed in details.
A soybean processing facility, in which refined oil, soy protein concentrate and soy protein isolate are produced, generates residues that if undergo additional industrial operations may result in new products with commercial value. The biorefinery concept is a topic widely discussed by governments, industry, and academics, considering it as a possible path to more sustainable economic development. Total biomass utilization is part of this concept. Therefore, this review aims to present the residues generated during soybean processing, the main composition and possible applications for each one of them, in order to better take advantage of soybean biomass. To do so, first, the process, products and residues were identified using academic material. Next, using Scopus database, a search for each residue was performed and possible applications for it were identified from scientific studies presented in the articles included in this databank. It was verified that, for every residue generated during soybean processing, more than one application was already studied, and they are here presented and discussed. Many interesting opportunities are emerging, such as the use of most of the residues for the production of several types of energy and chemicals that may serve as precursors for the production of many other valuable products, such as lactic acid and nanofibers. The production of enzymes, adsorbents and many other products was also found. However, most studies do not attain to economic or environmental performance of the proposed processes. {[
Aims: To clone and identify a gene (CmXYL3) coding D-xylulokinase from Candida maltosa Xu316 and understand its physiological function. Methods and Results: Based on the conserved regions of the known D-xylulokinase-encoding genes, a pair of degenerate primers was designed to clone the CmXYL3 gene from C. maltosa Xu316. The coding region and sequences flanking the CmXYL3 gene were obtained by PCR-based DNA walking method. Southern blotting analysis suggested that there is a single copy of the CmXYL3 gene in the genome. The open reading frame starting from ATG and ending with TAG stop codon encoded 616 amino acids with a calculated molecular mass of 68889.743 Da. The CmXYL3 gene under the control of the GPD1 promoter was heterologously expressed in Saccharomyces cerevisiae deficient in D-xylulokinase (Delta ScXKS1::LEU2) activity, and restored growth on D-xylulose. The specific activity of D-xylulokinase varied during xylose fermentation and was correlated with aeration level. After growth on different pentoses and pentitols as sole carbon sources, the highest specific activity of D-xylulokinase was observed on D-xylose. Conclusions: The CmXYL3 gene isolated from C. maltosa Xu316 encodes a novel D-xylulokinase that plays a pivotal role in xylulose metabolism. Significance and Impact of the Study: This is the first report that describes the isolation and cloning of D-xylulokinase gene (CmXYL3) from C. maltosa Xu316. D-xylulokinase is pivotal for growth and product formation during xylose metabolism. Better understanding of the biochemical properties and the physiological function of D-xylulokinase will contribute to optimizing fermentation conditions and determining the strategies for metabolic engineering of C. maltosa Xu316 for further improvement of xylitol yield and productivity.
Lignocellulosic biomass resource has been widely used as a natural resource for the synthesis of biofuels and bio-based products through pre-treatment, saccharification and fermentation processes. In this review, we delve into the environmental implications of bioethanol production from the widely utilized lignocellulosic biomass resource. The focus of our study is the critical stage of pre-treatment in the synthesis process, which also includes saccharification and fermentation. By collecting scientific data from the available literature, we conducted a comprehensive life cycle analysis. Our findings revealed substantial differences in the environmental burdens associated with diverse pre-treatment methods used for lignocellulosic biomass. These results highlight the importance of selecting environmentally benign pre-treatment techniques to promote the sustainability of bioethanol production. Future research directions are suggested, emphasizing the optimization of pre-treatment processes to further mitigate their environmental impact.
The utilization of lignocellulosic biomass in various applications has a promising potential as advanced technology progresses due to its renowned advantages as cheap and abundant feedstock. The main drawback in the utilization of this type of biomass is the essential requirement for the pretreatment process. The most common pretreatment process applied is chemical pretreatment. However, it is a non-eco-friendly process. Therefore, this review aims to bring into light several greener pretreatment processes as an alternative approach for the current chemical pretreatment. The main processes for each physical and biological pretreatment process are reviewed and highlighted. Additionally, recent advances in the effect of different non-chemical pretreatment approaches for the natural fibres are also critically discussed with a focus on bioproducts conversion.
Xylose reductase (XR) is an intermediate inducible enzyme of xylose metabolism responsible for the reduction of xylose into xylitol. It is an intracellular enzyme present in various facultative bacteria, yeasts, molds and algae in their cytoplasm. The active site of enzyme is polar in nature which is responsible for acid-base catalysis. The enzyme is folded into (beta/alpha)(8) barrel and its substrate specificity is through C-terminal region. XR is an emerging industrially important food enzyme due to its major application in production of xylitol. Xylitol has shown remarkable applications in other industrial sectors such as food, biofuels, pharmaceutical, medical, odontological, textiles and cosmetics. This enzyme has been purified and characterized to understand its physico-chemical properties and stability. Further, robust microbial strains with tolerance towards high substrate concentration and toxic compounds are required to be developed for successful exploitation of XR at industrial level using agrowaste materials.
The generation of biohydrogen as source of biofuel/bioenergy from the wide variety of biomass has gathered a substantial quantum of research efforts in several aspects. One of the major thrusts in this field has been the pursuit of technically sound and effective methods and/or approaches towards significant improvement in the bioconversion efficiency and enhanced biohydrogen yields. In this perspective, the present contribution showcases the views formulated based on the latest advances reported in dark fermentative biohydrogen production (DHFP), which is considered as the most feasible route for commercialization of biohydrogen. The potential prospects and future research avenues are also presented.
Considering the depletion of natural resources, growing environmental problems, massive demand for petroleum, the investigation of pyrolysis of lignocellulosic biomass for liquid biofuel (bio-oil) production rich in monocyclic aromatics is getting popular. However, the crude bio-oil has many shortcomings which can be mainly attributed to its high content of oxygen in primary products. Catalytic co-pyrolysis is considered an economical method for producing considerable biofuels to replace conventional energy. The addition of co-feedings and catalysts and suitable reactors could significantly enhance the yield of bio-oil and promote the generation of monocyclic aromatics. This paper is aimed to introduce the structure of the main components of lignocellulosic biomass and reveals the pyrolysis chemistry through the behaviors that occurred during the catalytic co pyrolysis. The recent progress and development in the field of biomass catalytic co-pyrolysis were comprehensively reviewed in terms of selection of biomass, pretreatment of raw materials, kinds of catalysts, application of co-feedings, and set of reactors, for promoting monocyclic aromatic hydrocarbon production in bio-oil and improving its quality.
Biochar is widely suggested as a soil amendment to improve soil physical properties for crop production. However, the heterogeneity between experiments in terms of biochar characteristics, experimental conditions and soil properties makes it difficult to compare and extrapolate results from different studies. We conducted a statistical meta-analysis of literature published between 2010 and 2019, and quantified biochar's impacts on soil bulk density (BD) and water retention variables, namely, soil water content held at field capacity (FC), wilting point (WP) and plant available water content (AW). Across all soil textural groups, biochar on average decreased BD by 9\%. FC and WP significantly increased for the coarse-textured soils (by 51\% and 47\%, respectively), and moderately for the medium-textured soils (by 13\% and 9\%, respectively). For the fine-textured soils, FC remained unchanged ( < 1\%), but WP marginally decreased by 5\%. Biochar significantly increased AW in the coarse-textured soils (by 45\%) compared to the medium- and fine-textured soils (by 21\% and 14\%, respectively) suggesting that biochar may have greater benefit on coarse-textured soils. We introduced a novel parameter called `biochar carbon added', estimated from biochar carbon content and the rate of application, which can be useful to make a sound comparison of biochar impacts on soil physical properties reported in different case studies when variable biochar attributes, experimental conditions and soil types have been used. The meta-analysis highlights again the need to provide adequate information on biochar experiments and soil water retention variables to allow better elucidation of the underlying mechanisms of biochar's impact on soil water retention and more.
Microbial lipid prepared by oleaginous yeasts from low-cost substrates for biodiesel production is promising to realize commercial success. Millions of tons of crude glycerol are generated every year due to the widespread availability of biodiesel. Recently, crude glycerol has been widely reintegrated for microbial lipogenesis on a laboratory scale. This review provides an overview of the status of crude glycerol-to-lipids routes by the oleaginous yeasts with a particular emphasis on the potential for glycerol channeling into lipid synthesis. The supplementation of auxiliary nutritional components is emphasized for realizing high lipid production from crude glycerol via oleaginous yeasts. Co-valorization of crude glycerol and low-cost substrates (nutrients) including protein-rich wastes, wastewater sludge, and lignocellulosic materials has gathered wide attention as novel strategy for lipid overproduction. Particularly, co-fermentation of glycerol and lignocellulosic sugars showed synergistic effect for lipogenesis. Highly-efficient pretreatment strategies to overcome the rigid structure of lignocelluloses and facilitate the enzymatic digestibility included crude glycerol-based organosolv processes. Therefore, a more integrated concept coupling crude glycerol-based pretreatment and glycerol/lignocellulosic hydrolysates co-utilization was highlighted, allowing a novel biodiesel industry integrating the traditional biodiesel plants and the cellulosic lipid-based microbial cell factories. The lipid profiles prepared from different crude glycerol-to-lipid routes showed high similarity to vegetable oils and indicated high-quality biodiesel properties. The upgrading of crude glycerol and low-cost substrates to micro-biodiesel offered both economic and environmental benefits.
The activated carbon based electrode materials are promising for applications in supercapacitors, fuel cells, and batteries due to their large surface area and porous structure. All the carbonaceous materials (CNTs, graphene, activated carbon) exhibit EDLCs type behavior based on the adsorption of ions at the electrode interface. On the other hand, the charge storage mechanism of pseudo-capacitive materials, including metal oxides and conducting polymers, is based on the rapid faradic reactions. Owing to this, the latter has a higher level of charge storage than the former, but at the same time, it suffers from a lack of conductivity and lowers cycle stability. To achieve a higher energy density for the supercapacitor without degrading its power density and cycle stability, one of the best solutions is to compound the carbon based materials with pseudocapacitive materials. This review briefly described the various carbon composites with metal oxides, but the main focus is on biomass-derived activated carbon for supercapacitor applications, as the green and sustainable source of energy is the demand of ever increasing global crisis. The ongoing challenges and future developments in this direction for building efficient energy storage systems are also addressed here.
The agricultural industry is one of the main economic contributors in developing countries, especially in tropical regions. Extensive land clearing has led to severe erosion within the watersheds, which increases the vulnerability of water catchments to natural disasters, such as floods. Cellulosic fibers, such as jute, sisal, kenaf, hemp, and coir, are gaining increasing worldwide attention for their potential application in controlling soil erosion, principally due to their remarkable biodegradable and physical properties. Nonetheless, the research on biocomposites in controlling soil erosion is limited compared to the natural fibers. This is perhaps due to poor availability and high cost of biodegradable polymers compared to natural fibers, which are abundant and inexpensive. Poor adhesive interactions between the matrix and natural fibers due to the hydrophilic characteristic of the fibers is another major drawback that limits the development of biocomposites for controlling soil erosion.
The management of agricultural waste has become very important because the inappropriate disposal yields negative effects on the environment. The resource recovery from agricultural waste which converts waste into available resources can reduce the waste and new resource consumption. This review summarizes the 2018 researches of over three hundred scholar papers from several aspects: agricultural waste, and, waste chemical characterization, agricultural waste material, adsorption, waste energy, composting, waste biogas, agricultural waste management, and others.
In the context of hydrogen production from biomass or organic waste with dark fermentation, this study analysed 55 studies (339 experiments) in the literature looking for the effect of operating parameters on the process performance of dark fermentation. The effect of substrate concentration, pH, temperature, and residence time on hydrogen yield, productivity, and content in the biogas was analysed. In addition, a linear regression model was developed to also account for the effect of nature and pretreatment of the substrate, inhibition of methanogenesis, and continuous or batch operating mode. The analysis showed that the hydrogen yield was mainly affected by pH and residence time, with the highest yields obtained for low pH and short residence time. High hydrogen productivity was favoured by high feed concentration, short residence time, and low pH. More modest was the effect on the hydrogen content. The mean values of hydrogen yield, productivity, and content were, respectively, 6.49\% COD COD-1, 135 mg L-1 d(-1), 51\% v/v, while 10\% of the considered experiments obtained yield, productivity, and content of or higher than 15.55\% COD COD-1, 305.16 mg L-1 d(-1), 64\% v/v. Overall, this study provides insight into how to select the optimum operating conditions to obtain the desired hydrogen production.
Enzymatic hydrolysis accounts for 20\% of the total cost in the conversion process of lignocellulosic biomass into bioethanol. Therefore, production of biomass-degrading enzymes by using lignocellulosic residue as a fermentation substrate may be an alternative to decrease the production costs. In this study, corncob (CC) has been pretreated by liquid hot water (LHW) at 200 degrees C for 30 min and used as inducer source for production of biomass-degrading enzymes by Trichoderma reesei MUM 97.53. The pretreatment was used to increase the cellulose content and the accessibility to lignocellulosic material. Although the filamentous fungus secreted a broad range of cellulolytic and hemicellulolytic enzymes when grown on untreated CC, higher enzyme productions were obtained when cultured on LHW-pretreated CC in a 2-L stirred tank bioreactor (STB). Besides, the effects of aeration (2 and 4 vvm) and agitation (150 and 250 rpm) rates on enzyme production were studied by submerged fermentation in a batch STB and correlated with the volumetric oxygen transfer coefficient (k(L)a). Maximal cellulase, xylanase, and beta-xylosidase productions were found at 150 rpm and 4 vvm, while the highest beta-glucosidase levels were obtained at 150 rpm and 2 vvm, that corresponded to k(L)a values of 32.50 h(-1) and 16.41 h(-1), respectively. At higher agitation, a lower enzymatic production was observed probably due to the high shear stress in the fungal hyphae.
Ordinary Portland cement is the highest produced cement type in the world, however its production is high energy consumption means expensive, huge natural resource consumptive, and creating high environmental pollution. Hence many researchers studied to reduce the effect of ordinary Portland cement by substituting artificial and natural supplementary cementitious materials (SCMs) commonly in a concrete/mortar mixture. However, the comprehensive effect of different SCMs on various properties of cement composite materials are not well known. So the present study sought to review the effect of different natural and artificial SCMs on the durability and mechanical properties of cement composites, especially due to their doses, types, chemical composition, and physical properties. Hence the review shows that many SCMs used by literatures from different places satisfy ASTM replacement standard based on their chemical compositions. Also, the review indicated as adding 5-20\% of different SCMs positively affect mechanical properties, durability, and microstructures of the cement composite materials, specifically as most researchers found isolately adding of 15\% SCMs such as bentonite, kaolin, and biomass, 20\% addition of volcanic ash and 10\% employment of fly ash, silica fume, and zeolite to the cement composites achieves the most optimum compressive and split tensile strength. These observations reveal that most natural pozzolana can more replace cement to give optimum strength, hence can more reduce energy consumption, production cost, and environmental pollution comes due to cement production. Furthermore, most researchers found employing different SCMs generally improves durability, however there is a limited study on the effect of silica fume on water absorption and acidic attack resistance of cementitious materials. Therefore, it is recommended that future research should also focus more to know the effect of silica fume on the durability of cement composites.
Energy plays a crucial role in the sustainable development of modern nations. Today, hydrogen is considered the most promising alternative fuel as it can be generated from clean and green sources. Moreover, it is an efficient energy carrier because hydrogen burning only generates water as a byproduct. Currently, it is generated from natural gas. However, it can be produced using other methods, i.e., physicochemical, thermal, and biological. The biological method is considered more environmentally friendly and pollution free. This paper aims to provide an updated review of biohydrogen production via photofermentation, dark fermentation, and microbial electrolysis cells using different waste materials as feedstocks. Besides, the role of nanotechnology in enhancing biohydrogen production is examined. Under anaerobic conditions, hydrogen is produced during the conversion of organic substrate into organic acids using fermentative bacteria and during the conversion of organic acids into hydrogen and carbon dioxide using photofermentative bacteria. Different factors that enhance the biohydrogen production of these organisms, either combined or sequentially, using dark and photofermentation processes, are examined, and the effect of each factor on biohydrogen production efficiency is reported. A comparison of hydrogen production efficiency between dark fermentation, photofermentation, and two-stage processes is also presented.
The micro foaming performance, moisture resistance and dynamic viscosity of scCO(2)-aid glutaraldehyde/hexametaphosphate/thermoplastic tapioca starch (GA/SHMP/TOS) foams were considerably improved by proper NaOH treatment. The expansion ratio, resilience rate, dynamic viscosity values of these NaOH modified foams improved to a maximum, as the time for NaOH treatment approached a proper value. The dynamic viscosity, expansion ratio and resilience rate of the scCO(2)-aid GA/SHMP/TOS foams modified using 110 atm scCO(2)-pressure, the proper alkali treatment time, SHMP loading and varying montmorillonite (MMT) loadings improved further, as their MMT loadings approached a proper value of 2.5 part per hundred parts of tapioca starch (PHTOS). Relatively large dynamic viscosity (7.1x10(4) Pa center dot s), extremely large expansion ratio (similar to 75), cell density (1.1x10(9) cells/cm(3)) and/or resilience rate (similar to 80\%) were acquired for the scCO(2)-aid GA/SHMP/TOS/MMT foam modified using the proper alkali treatment time and MMT loading. Thermal analyses results showed that crystallization onset temperatures and crystallization rates of scCO(2)-aid GA/SHMP/TOS/MMT foams modified using the proper alkali treatment time and varying MMT loadings improved to a highest value by adding 2.5 PHTOS of MMT nano-platelets. Possible reasons accounting for the considerably improved micro foaming performance of scCO(2)-aid GA/SHMP/TOS/MMT foams modified using the proper alkali treatment time and MMT loading are proposed in this study.
As mentioned in several recent reviews, biomass-based furfural is attracting increasing interest as a feasible alternative for the synthesis of a wide range of non-petroleum-derived compounds. However, the lack of environmentally friendly, cost-effective, and sustainable industrial procedures is still evident. This review describes the chemical and biological routes for furfural production. The mechanisms proposed for the chemical transformation of xylose to furfural are detailed, as are the current advances in the manufacture of furfural from biomass. The main goal is to overview the different ways of improving the furfural synthesis process. A pretreatment process, particularly chemical and physico-chemical, enhances the digestibility of biomass, leading to the production of > 70 \% of available sugars for the production of valuable products. The combination of heterogeneous (zeolite and polymeric solid) catalyst and bi-phasic solvent system (water/GVL and water/CPME) is regarded as an attractive approach, affording > 75 \% furfural yield for over 80 \% of selectivity with the possibility of catalyst reuse. Microwave heating as an activation technique reduces reaction time at least tenfold, making the process more sustainable. The state of the art in industrial processes is also discussed. It shows that, when sulfuric acid is used, the furfural yields do not exceed 55 \% for temperatures close to 180 degrees C. However, the MTC process recently achieved an 83 \% yield by continuously removing furfural from the liq-uid phase. Finally, the CIMV process, using a formic acid/acetic acid mixture, has been developed. The economic as-pects of furfural production are then addressed. Future research will be needed to investigate scaling-up and biological techniques that produce acceptable yields and productivities to become commercially viable and competitive in furfu-ral production from biomass.
Due to rapid population growth and industrialization, the generation of different industrial and agricultural wastes has surged in the past few decades. In this study, burnt clay bricks are prepared to investigate the synergistic and individual effect of glass sludge (GS), marble sludge (MS), and rice husk (RH) on the physical, mechanical, durability, and thermal properties of brick samples. Results show that the addition of waste materials (GS, MS, and RH) reduces the shrinkage, weight per unit area, and thermal conductivity of brick samples. All the brick samples incorporating different waste materials show efflorescence much lower than 10\%. Furthermore, no brick sample faced any cracking even after 50 freeze-thaw cycles. The mass loss of brick samples incorporating 25\% of GS is observed lower than the specified limit of ASTM C67 and are classified as freeze-thaw resistant brick samples. All the brick samples incorporating different waste materials satisfy the minimum compressive strength and modulus of rupture requirements for building bricks and can be used in a moderate weather-resistant environment, leading to sustainable masonry construction. Furthermore, all the brick samples show leaching toxicity values much lower than the specified limits of the Environmental Protection Agency. The scanning electron microscopic images also support the results of porosity and water absorption of brick samples observed in this study. Based on the results, all the combinations of waste materials considered in this study for making brick samples can be used for masonry construction leading towards landfill reduction and the production of eco-friendly bricks.
Carbon dioxide (CO2) has attracted great interest as a catalyst and reaction medium for the conversion of lignocellulosic biomass into value-added commodity chemicals. In this review, we focus on the use of CO2 in the pretreatment of raw biomass (for example, to isolate sugar monomers from the polymeric components of lignocellulosic biomass) and subsequent hydrolysis, as well as in different reactions to yield valuable platform chemicals from feedstocks derived from the raw biomass (e.g., dehydration, hydrogenation, and hydrodeoxygenation). In this respect, this review gives a summary of the enhancement in biomass conversion reactions achievable by utilizing CO2 and the roles of CO2 in this enhancement. Recent achievements (mostly in the past five years) in CO2-catalyzed and CO2-assisted biomass conversion reactions in various systems are highlighted. The prospect of transforming biomass feedstocks to platform chemicals using CO2 is also discussed, and important points and challenges facing further research into the CO2-driven conversion of biomass are highlighted.
The increasing interest for cellulose-based products has resulted in the development of processes for the controlled deconstruction of cellulose into cellulose nanomaterials, such as cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). These nanomaterials can significantly increase the diverse applications of cellulose by exploring their nanometric scale options and improved properties for various high-volume, low-volume, and emerging/novel applications. Among the nanocellulose production processes, the enzyme-mediated methods are environment friendly and with expected lower capital and operating expenditures compared to traditional processes. In addition, it creates the unique possibility of fine-tuning the process to tailor nanocellulose properties that are suitable for specific applications. This review comprehensively examines the application of enzymes in the isolation of nanocelluloses. To date, no enzyme preparation for application to nanocellulose production is available commercially. Therefore, a fundamental understanding of potential enzymes focusing mainly on their differentiated properties, mechanism and alterations promoted to cellulose at different levels is first provided. This is to shed light on the enzyme properties that can be exploited for application in nanocellulose isolation. Then, the current state of the stand-alone and integrated enzyme-mediated processes is reviewed as well as the properties and yield of the isolated nanocelluloses in comparison to nanocelluloses obtained by traditional processes. In addition, the potential of enzyme-mediated functionalization has been discussed as a promising method that imparts unique properties to nanocelluloses, further diversifying their market. A detailed discussion on the challenges and opportunities for the major technical and economic factors that impact nanocellulose price has been included as well.
The present fossil fuel-based energy sector has led to significant industrial growth. On the other hand, the dependence on fossil fuels leads to adverse impact on the environment through releases of greenhouse gases. In this scenario, one possible substitute is biohydrogen, an eco-friendly energy carrier as high-energy produces. The substrates rich in organic compounds like organic waste/wastewater are very useful for improved hydrogen generation through the dark fermentation. Thus, this review article, initially, the status of biohydrogen production from organic waste and various strategies to enhance the process efficiency are concisely discussed. Then, the practical confines of biohydrogen processes are thoroughly discussed. Also, alternate routes such as multiple process integration approach by adopting biorefinery concept to increase overall process efficacy are considered to address industrial-level applications. To conclude, future perspectives besides with possible ways of transforming dark fermentation effluent to biofuels and biochemicals, which leads to circular bioeconomy, are discussed.
A novel facility from the green technologies to integrate biomass-based carbohydrates, lignin, oils and other materials extraction and transformation into a wider spectrum of marketable and value-added products with a zero waste approach is reviewed. With ever-increasing scientific knowledge, worldwide economic and environmental consciousness, demands of legislative authorities and the manufacture, use, and removal of petrochemical-based by-products, from the last decade, there has been increasing research interests in the value or revalue of lignocellulose-based materials. The potential characteristics like natural abundance, renewability, recyclability, and ease of accessibility all around the year, around the globe, all makes residual biomass as an eco-attractive and petro-alternative candidate. In this context, many significant research efforts have been taken into account to change/replace petroleum-based economy into a bio-based economy, with an aim to develop a comprehensively sustainable, socially acceptable, and eco-friendly society. The present review work mainly focuses on various aspects of bio-refinery as a sustainable technology to process lignocellulose `materials' into value-added products. Innovations in the bio-refinery world are providing, a portfolio of sustainable and eco-efficient products to compete in the market presently dominated by the petroleum-based products, and therefore, it is currently a subject of intensive research. (C) 2017 Elsevier B.V. All rights reserved.
Extremely high surface area, porosity, and other surface properties make activated carbons (ACs) a versatile and universally acclaimed adsorbent. High production costs limit the use of ACs as adsorbents, and this is a major driver for worldwide research targeting cheap precursors to reduce the production cost and to enhance the adsorption efficiency. This review highlights the preparation of ACs from various precursors, their functionalization, characterization, and their applications in water decontamination. A list of cost-effective precursors derived from agricultural waste materials along with the pollutants removed is presented. ACs can be functionally modified to develop highly efficient and adsorbate selective materials. Enhancement of the adsorption efficiency of ACs for inorganic pollutants and metal ions can be achieved by chemical modification, while physical modification of ACs via thermal treatment can enhance the pore size and surface area. A summary of the various chemical, physical, and biological processes that are utilized for these modifications is presented.
Bioethanol is an alternative to motor fuel, generated through the fermentation of sugars released from the hydrolyzed cellulosic material. For efficient ethanol production, total utilization of sugars needs an improved fermentation approach i.e. Simultaneous Saccharification and Co-fermentation (SSCF). SSCF is the current, advanced, close to commercialization approach that is being continuously improved for high ethanol titer, total sugar (hexose + pentose) utilization, high mass transfer, reducing the feedback inhibition, and one-pot conversion strategies. The major improvement strategies such as enhancing the saccharification rate, engineering microbes for co-fermentation, enhancing mass transfer through impeller designing, and the role of conditional factors on the SSCF process are reviewed in this study.
Sulfonated carbon-based catalysts (SCC) are favorable heterogeneous acids for acid-catalyzed reactions including esterification and transesterification for biodiesel production. They are covalently functionalized with -SO3H groups via C-PhSO3H or C-SO3H linkages with special carbon structures. To date, the types of SCC for biodiesel production ranges from biochar (BC), activated carbon (AC), graphene, graphite oxides, multiwalled carbon nanotubes, order mesoporous carbon, and graphitic carbon nitride. Lignocellulosic and biomass wastes are important carbon precursors for low-cost BC and AC production. This review critically reviews and summarizes the most up-to-date research progress in the evolution of SCC for biodiesel production. Systematic discussions and comparisons on the different carbon materials, preparation methods, and sulfonation preparation parameters which directly affect the physicochemical attributes and catalytic performance are provided. The applications and reusability studies of these materials in biodiesel production are also included. Finally, the challenges to be addressed and future prospects of the research direction on the applications of SCC for biodiesel production are discussed.
The volume of industrial lignin is expected to increase with the deployment of biorefineries that convert lignocellulosic biomass to renewable chemicals and fuels. Interest in using lignin for value-added biomedical applications requires understanding of its effects on mammalian and microbial cells, which has been impaired by the toxicity of the solvents used to solubilize lignin. In this study, lignin is solvated in zwitterionic Good's buffers compatible with culture media. Up to 100 mg lignin can be solvated in 1 ml of 3-morpholinopropane-1-sulfonic acid (MOPS, pH 7.2) within 60 min at room temperature, whereby MOPS acts as a chaotropic agent. The addition of MOPS-solvated lignin to cultures of Staphylococcus aureus UAMS-1 containing a subinhibitory concentration of tunicamycin reduced growth more than 99\% compared to tunicamycin alone, making lignin of interest as an antibiotic adjuvant. This effect of lignin is attributed to damage to the bacterial cell membrane.
The global economy's growths due to industrialization, accompanied by urbanization high rate, have led to severe anthropogenic pollution impacting both the environment and human health. Regarding particularly the aquatic systems' chemical pollution, as resulting mainly from the release of liquid effluents containing dye molecules and organic pollutants, it is therefore necessary to use innovative processes for treating the polluted water. At first sight, adsorption seemed like an excellent process due to its simplicity and efficiency, but this technique simply moves the dye from an aqueous medium to the adsorbent surface, thus creating sludges which are new pollution forms. Hence, we need to treat this polluted adsorbent in order to recover the removed dye and to reuse once more the adsorbent for others dye removal adsorption cycles. This review focuses on regenerating low-cost adsorbents (LCAs), saturated with dyes, by using different desorbing agents and on exploring their potential to be reused. These low-cost materials have been classified into four classes based on their origin: agricultural solid wastes; industrial by-products and wastes; natural materials; and sea materials and biomasses. Different chemical agents such as acids, bases, salts, organic solvents, alcohols, and chelating reagents have been used as eluents to regenerate the dye-covered adsorbents. Therefore, in the present review citing 210 literature articles, it is demonstrated the excellent regeneration and high reusability of the LCAs suited for dye removal from environmental wastewater. In this review paper, we show that the agricultural solid wastes (39.56\%) are the most regenerated and reused, in comparison to, sea materials and biomasses (22.31\%), industrial by-products and wastes (18.71\%), and natural materials (19.42\%).
Supercritical water gasification (SCWG) is a remarkably efficient technology for converting wet biowaste (such as food waste, paper industrial waste, sewage sludge, agricultural waste, and forestry residue) into energy in the form of hydrogen-rich syngas. Catalysts have been widely used for promoting the hydrogen production rate of SCWG at mild reaction temperatures. In this regard, transition metal-based catalysts have attracted extensive attention from researchers due to their excellent performance and recyclability. Herein, the catalytic effects of transition metal-based catalysts on the SCWG of biowaste are reviewed, including the influence of active components, synthetic methods, and support materials. The modification of transition metal-based catalysts (rare earth oxide-promoted catalysts, noble-metal bimetallic catalysts, noble-metal-free bimetallic catalysts, and alkaline-earth metal-promoted catalysts) is also discussed. Finally, technical challenges and future perspectives for the development of transition metal-based catalysts in the SCWG of biowaste are presented. This review paper aims at providing an important reference for the design of transition metal-based catalysts with excellent catalytic performance and physicochemical properties and their applications in the SCWG of biowaste.
Utilizing various wastes in ceramic production has been growing worldwide. This work provides an extensive literature review on the utilization of food, agricultural, and industrial wastes as pore-forming agents (PFAs) in porous ceramic production. The literature conducted since 2010 indicates that waste based porous ceramics has versatile properties with excellent performances. Determination of waste material and clay properties as well as processing conditions such as material composition, sintering temperature, and compaction pressure, which influence pore formation in ceramics, has been comprehensively provided. These factors significantly influence the properties of the resulting porous ceramics, including physical, mechanical, and toxicity properties. Recycling food, agricultural, and industrial wastes for increased energy saving and green ceramic production can be realized as an economical and practical approach to sustainable waste management, which align well with achieving sustainability in a circular economy and the UNESCO's Sustainability Development Goals (SDG). Achieving zero food, agricultural, and industrial wastes can eliminate environmental burdens and pave the way for closed-loop production. In overall, the waste-based porous ceramics can pave the way for sustainable environments, expanding the economic sector, particularly alternative building materials. (c) 2021 Elsevier Ltd. All rights reserved. 1. Introduction 2 2. Overview of porous ceramics 3 3. Properties of food, agricultural, and industrial wastes 3 3.1. Chemical and mineralogical properties 3 3.2. Thermal properties 6 4. Physical and mechanical properties of porous ceramics incorporated with waste materials 6 5. Toxicity of porous ceramics incorporated with waste materials 8 6. Performances and sustainability of porous ceramics incorporated with waste materials 9
The goal of cost-effective production of fuels and chemicals from biomass has been a substantial driver of the development of the field of metabolic engineering. The resulting design principles and procedures provide a guide for the development of cost-effective methods for degradation, and possibly even valorization, of plastic wastes. Here, we highlight these parallels, using the creative work of Lonnie O'Neal (Neal) Ingram in enabling production of fuels and chemicals from lignocellulosic biomass, with a focus on ethanol production as an exemplar process.
Acetic acid, a potential growth inhibitor, commonly occurs in lignocellulosic hydrolysates. The growth of Cupriavidus necator DSM 545 and production of poly(3-hydroxybutyrate) (PHB) by this bacterium in a glucose-based medium supplemented with various initial concentrations of acetic acid are reported. The bacterium could use both glucose and acetic acid to grow and produce PHB, but acetic acid inhibited growth once its initial concentration exceeded 0.5 g/L. As acetic acid is an unavoidable contaminant in hydrolysates used as sugar sources in commercial fermentations, a mathematical model was developed to describe its impact on growth and the production of PHB. The model was shown to satisfactorily apply to growth and PHB production data obtained in media made with acetic-acid-containing hydrolysates of Napier grass and oil palm trunk as carbon substrates.
The utilization of biomass, the only carbon-bearing renewable energy source, is critical for environmental and energy sustainability as well as carbon neutrality. Pyrolysis is the efficient conversion of biomass to fuel gas, liquid oil, and solid char. It is necessary to understand the mechanism of biomass pyrolysis for valuable and efficient utilization. In this review, recent progress with respect to biomass pyrolysis properties, the pyrolysis process, and product upgrading strategies focusing on carbon-based high-value liquid fuels and carbon-bearing materials are summarized. First, the correlations between the pyrolysis behavior and biomass structure and process conditions are considered. The mechanisms of the biomass pyrolysis of hemicellulose, cellulose, and lignin as well as the potential effect of inorganic matter on biomass pyrolysis are discussed. Furthermore, the regulation and controlling strategies for the biomass pyrolysis of high-value products are outlined. Finally, the challenges and prospects are discussed in order to provide a comprehensive picture of biomass pyrolysis development, which is significant for the understanding of biomass pyrolysis and the development of biomass utilization technology.\& COPY; 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
In the past decade, ionic liquids (ILs) have received enormous interest as solvents for cellulose. They have been studied intensively for fractionation and biorefining of lignocellulosic biomass, for dissolution of the polysaccharide, for preparation of cellulosic fibers, and in particular as reaction media for the homogeneous preparation of highly engineered polysaccharide derivatives. ILs show great potential for application on a commercial scale regarding recyclability, high dissolution power, and their broad structural diversity. However, a critical analysis reveals that these promising features are combined with serious drawbacks that need to be addressed in order to utilize ILs for the efficient synthesis of cellulose derivatives. This review presents a comprehensive overview about chemical modification of cellulose in ILs. Difficulties encountered thereby are discussed critically and current as well as future developments in this field of polysaccharide research are outlined.
This paper examines the compressive, flexural and tensile strength, ultrasonic pulse velocity, unit weight, water absorption, freeze-thawing, thermal and abrasion resistance, and microstructural properties of Interlocking Concrete Block Paving (ICBP) containing major industrial and agricultural wastes along with an assessment of their environmental effects, with a specific focus on recent work. The color, shape, and patterns of the blocks, their advantages, and their relationship with sustainability are discussed in this study. In addition, a limited number of studies that investigated the use of other byproducts are presented. Based on a review of the existing studies in the literature, recommendations are made for future studies. It has been determined that up to 30\% inclusion of waste evaluated in ICBP provides optimal performance in terms of the evaluated properties. Moreover, as ICBP provides opportunities for low-energy concrete block production, the environmental burden and total cost of concrete and concrete block pavements can be reduced. Considering these benefits, studies performed on this subject seem promising. However, one of the missing points in ICBP is that the surface layer is not homogeneous due to the presence of various material types due to the coating design and analysis method. Therefore, modified slab analysis, layered elastic analysis, and finite element analysis can be used to analyze ICBP in detail.
Xylooligosaccharides (XOS) have gained increased interest as prebiotics during the last years. XOS and arabinoxylooligosaccharides (AXOS) can be produced from major fractions of biomass including agricultural by-products and other low cost raw materials. Endo-xylanases are key enzymes for the production of (A) XOS from xylan. As the xylan structure is broadly diverse due to different substitutions, diverse endo-xylanases have evolved for its degradation. In this review structural and functional aspects are discussed, focusing on the potential applications of endo-xylanases in the production of differently substituted (A) XOS as emerging prebiotics, as well as their implication in the processing of the raw materials. Endo-xylanases are found in at least eight different glycoside hydrolase families (GH), and can either have a retaining or an inverting catalytic mechanism. To date, it is mainly retaining endo-xylanases that are used in applications to produce (A) XOS. Enzymes from these GH-families (mainly GH10 and GH11, and the more recently investigated GH30) are taken as prototypes to discuss substrate preferences and main products obtained. Finally, the need of new and accessory enzymes (new specificities from new families or sources) to increase the yield of different types of (A) XOS is discussed, along with in vitro tests of produced oligosaccharides and production of enzymes in GRAS organisms to facilitate use in functional food manufacturing.
Producing more food for a growing population in the coming decades, while at the same time combating environmental issues, is a huge challenge faced by the worldwide population. The risks that come with climate change make the mission more daunting. Billion tons of agriculture by-products are produced each year along the agricultural and food processing processes. There is a need to take further actions on exploring the inner potential of agro-waste to stand out as food ingredient to partially or fully substitute the foods in orthodox list. Some of the agro-waste contains the most valuable nutrients in the plant and it is truly a ``waste{''
Agar is modified by chemical methods to improve its functional properties and meet the increasing demand of the market. Some of the functional properties of agar are improved after chemical modification, while other properties are reduced, especially gel strength. This study aimed to comprehensively improve the functional properties of agar through acylation and crosslinking by reacting with maleic anhydride. C-13 NMR indicated the maleylation reaction was preferred at the C2 hydroxyl group of D-galactose, and the crosslinking reactions occurred at the C2 and C6 hydroxyl groups of D-galactose in different agar chains. Interestingly, the maleylated agar monoester had higher gel transparency (1.5\%, w/v) of up to 76\% than the native agar (58\%). However, it showed a significant decrease in gel strength from 783 g/cm(2) to 403 g/cm(2), while crosslinking endowed agar with higher gel strength (845 g/cm(2)) and gel transparency (78.4\%). The high transparency of the modified agar plate made colony observation and colony counting easy. Maleylation of agar further enhanced the freeze-thaw stability of agar gel (24.8\%, 7th freeze-thaw cycles). Overall, the maleylated agar possessed superior functional properties, and it could be used as food, bacteriological, and biotechnological agar.
The fluorescent carbon dot is a novel type of carbon nanomaterial. In comparison with semiconductor quantum dots and fluorescence organic agents, it possesses significant advantages such as excellent photostability and biocompatibility, low cytotoxicity and easy surface functionalization, which endow it a wide application prospect in fields of bioimaging, chemical sensing, environmental monitoring, disease diagnosis and photocatalysis as well. Biomass waste is a good choice for the production of carbon dots owing to its abundance, wide availability, eco-friendly nature and a source of low cost renewable raw materials such as cellulose, hemicellulose, lignin, carbohydrates and proteins, etc. This paper reviews the main sources of biomass waste, the feasibility and superiority of adopting biomass waste as a carbon source for the synthesis of carbon dots, the synthetic approaches of carbon dots from biomass waste and their applications. The advantages and deficiencies of carbon dots from biomass waste and the major influencing factors on their photoluminescence characteristics are summarized and discussed. The challenges and perspectives in the synthesis of carbon dots from biomass wastes are also briefly outlined.
The marine oleaginous protist Aurantiochytrium sp. (Schizochytrium sp.) is a well-known docosahexaenoic acid (DHA) producer and its different DHA products are the ideal substitute for the traditional fish oil resource. However, the cost of the DHA products derived from Aurantiochytrium sp. (Schizochytrium sp.) is still high, limiting their wide applications. In order to reduce the cost or improve the productivity of DHA from the microbial resource, many researches are focusing on exploring the renewable and low-cost materials as feedbacks, and/or the stimulators for biomass and DHA production. In addition, the genetic engineering is also being used in the Aurantiochytrium sp. (Schizochytrium sp.) system for further improvement. These break the bottleneck of the DHA production by Aurantiochytrium sp. (Schizochytrium sp.) in some degree. In this review, the strategies used currently to reduce cost and improve DHA productivity, mainly from the utilizations of low-cost materials and effective stimulators to the genetic engineering perspectives, are summarized, and the availabilities from the cost perspective are also evaluated. This review provides an overview about the strategies to revolve the production cost and yield of the DHA by Aurantiochytrium sp. (Schizochytrium sp.), a theoretical basis for genetic modification of Aurantiochytrium sp. (Schizochytrium sp.), and a practical basis for the development of DHA industry.
Countless years of industrialization have led to the continuous depletion of nonrenewable resources and high levels of pollution. The overuse of nonrenewable resources has served as a motivation for intensive research and development of new types of green bio-based and degradable feedstocks derived from natural sources. Lignocellulosic biomass is one of the least used bio-resources in the world, consisting mainly of lignin, cellulose, and hemicelluloses. This type of biomass is plentiful in biopolymers in nature and is obtained from several sources, among which are the residues from agricultural and industrial lignocellulosic crops. The cellulose extracted from the biomass can be depolymerized giving rise to an extraordinary nanometer scale bio-based material. Abundance, biodegradability, renewability and low-cost, coupled with excellent mechanical properties appoint nanocellulose (NC) as one of the most promising nanometric biomaterials. In recent years, the improvement of the production processes, as well as the properties of the nanocellulose, has been extensively studied, thus exploring a range of applicability in diverse technological areas. Due to its mechanical properties, the reinforcement in polymeric bionanocomposites has been pointed out as one of the most interesting applications of the NC. This review focuses on the recent developments about the valorization of lignocellulosic biomass obtained from different lignocellulosic agro-industrial crops, as a source of NC, by discussing (i) structure and properties of lignocellulosic biomass (ii) promising eco-friendly biomass pre-treatment and nanocellulose production procedures, (iii) recent technological applications. Ultimately, the critical assessment of the current knowledge will allow the identification of prospects, limitations and future opportunities of this nanomaterial.
The use of lignocellulosic biomass (LCB) as feedstock has received increasing attention as an alternative to fossilbased refineries. Initial steps such as pretreatment and enzymatic hydrolysis are essential to breakdown the complex structure of LCB to make the sugar molecules available to obtain bioproducts by fermentation. However, these steps increase the cost of the bioproduct and often reduces its competitiveness against synthetic products. Currently, the use of surfactants has shown considerable potential to enhance lignocellulosic biomass processing. This review addresses the main mechanisms and role of surfactants as key molecules in various steps of biorefinery processes, viz., increasing the removal of lignin and hemicellulose during the pretreatments, increasing enzymatic stability and enhancing the accessibility of enzymes to the polymeric fractions, and improving the downstream process during fermentation. Further, technical advances, challenges in application of surfactants, and future perspectives to augment the production of several high value-added bioproducts have been discussed.
Olive mill wastewater (OM) contains a variety of assimilable carbon sources and therefore it can be regarded as fermentation medium for the production of high-added value products rather than as a waste material. In this study, OMW enriched with low cost carbon sources was used as culture medium for selected yeast strains cultivated in flasks and bioreactors. Lipomyces starkeyi NRRL Y- 11557 and Yarrowia lipolytica strains showed a noteworthy ability to accumulate lipids (15-25\%, w/w) cultivated on OMW based media. Oleic acid was the major fatty acid in the lipids produced by the above mentioned yeasts followed by palmitic acid. On OMW media enriched with glycerol Y lipolytica A6 strain produced also mannitol in considerable amounts (i.e. 13.4 g/L), while Y. lipolytica LGAM S (7) strain produced high quantities of citric acid (i.e. 30.3 g/L). Candida tropicalis LFMB 16 and Saccharomyces cerevisiae MAK-1, cultivated under non-aseptic conditions on OMW media enriched with glucose produced 21.9 and 31.3 g/L of ethanol, respectively. Remarkable phenolic removal was performed by strains of Y. lipolytica, C tropicalis and S. cerevisiae, while color removal was only observed in trials performed with C tropicalis and S. cerevisiae. The present study provides a new perspective for the production of high-added value metabolites having biotechnological interest from OMW based media along with OMW management. (C) 2016 Elsevier Ltd. All rights reserved.
Biomass has emerged as an abundant and relatively low cost carbon resource alternative to fossil fuel resources in the sustainable production of specialty chemicals and biofuel. Levulinic acid is an attractive platform chemical. Upgrading of levulinic add produces levulinate esters, which serve as a transportation fuel and fuel additive. The present review focuses on the development of sustainable conversion of biomass into levulinic add and levulinate esters via ionic liquids dual solvent catalysts. The synthesis routes of levulinic add and levulinate esters and the corresponding ionic liquids are introduced. The biomass pretreament, as well as the conversions of lignocellulosic biomass and their derivatives into levulinic add and levulinate esters, are detailed in relation to the catalytic role, properties, and performance of acidic ionic liquids. Finally, the operating conditions affecting the ionic liquids catalytic conversions are discussed as part of a comprehensive review of this topic.
The addition of residues into clay matrix has been widely reported and reviewed during last decade. The heterogeneity of wastes and the lack of detailed information make difficult to provide an overall framework for comparing results. With the aim of showing an acceptable estimation of fired clay bricks properties, when wastes are added, this paper summarizes raw materials characterization and methods of most cited papers. Despite mechanical, physical and thermal properties highly depend on several parameters when residues are classified and results are related to the relative variation of density, a good correlation, between different papers, is found. (C) 2016 Elsevier Ltd. All rights reserved.
Primary material supply is the heart of engineering and sciences. The depletion of natural resources and an increase in the human population by a billion in 13 to 15 years pose a critical concern regarding the sustainability of these materials; therefore, functionalizing renewable materials, such as nanocellulose, by possibly exploiting their properties for various practical applications, has been undertaken worldwide. Nanocellulose has emerged as a dominant green natural material with attractive and tailorable physicochemical properties, is renewable and sustainable, and shows biocompatibility and tunable surface properties. Nanocellulose is derived from cellulose, the most abundant polymer in nature with the remarkable properties of nanomaterials. This article provides a comprehensive overview of the methods used for nanocellulose preparation, structure-property and structure-property correlations, and the application of nanocellulose and its nanocomposite materials. This article differentiates the classification of nanocellulose, provides a brief account of the production methods that have been developed for isolating nanocellulose, highlights a range of unique properties of nanocellulose that have been extracted from different kinds of experiments and studies, and elaborates on nanocellulose potential applications in various areas. The present review is anticipated to provide the readers with the progress and knowledge related to nanocellulose. Pushing the boundaries of nanocellulose further into cutting-edge applications will be of particular interest in the future, especially as cost-effective commercial sources of nanocellulose continue to emerge.
Hydrothermal pretreatment (HTP) using only water offers great potential to reduce the overall cost of the bioconversion process. However, traditional HTP performed in a batch has limitations in removing lignin and often needs to be performed under severe conditions to achieve reasonable pretreatment effects. Lignin left in the pretreated residue at these conditions is also highly condensed, thus possessing an even more adverse impact on the hydrolysis process, which requires high enzyme loadings. To address these technical challenges, HTP performed in a flow-through configuration was developed to simultaneously achieve near-complete hemicellulose recovery, high lignin removal and high sugar release. Despite facing challenges such as potentially large water usage, flow-through HTP still represents one of the most cost-effective and eco-friendly pretreatment methods. This review mainly covers the latest cutting-edge innovations of flow-through HTP along with structural and compositional changes of cellulose, hemicellulose, and lignin before and after pretreatment.
The endophytic fungi represent a potential source of microorganisms for enzyme production. However, there have been only few studies exploiting their potential for the production of enzymes of industrial interest, such as the (hemi)cellulolytic enzymatic cocktail required in the hydrolysis of lignocellulosic biomass. Here, a collection of endophytic fungi isolated from mangrove tropical forests was evaluated for the production of carbohydrolases and performance on the hydrolysis of cellulose. For that, 41 endophytic strains were initially screened using a plate assay containing crystalline cellulose as the sole carbon source and the selected strains were cultivated under solid-state fermentation for endoglucanase, beta-glucosidase, and xylanase enzyme quantification. The hydrolysis of a cellulosic material with the enzymes from endophytic strains of the Aspergillus genus resulted in glucose and conversion values more than twofold higher than the reference strains (Aspergillus niger F12 and Trichoderma reesei Rut-C30). Particularly, the enzymes from strains A. niger 56 (3) and A. awamori 82 (4) showed a distinguished saccharification performance, reaching cellulose conversion values of about 35\% after 24 h. Linking hydrolysis performance to the screening steps played an important role towards finding potential fungal strains for producing enzymatic cocktails with high saccharification efficiency. These results indicate the potential of mangrove-associated endophytic fungi for production of carbohydrolases with efficient performance in the hydrolysis of biomass, thus contributing to the implementation of future biorefineries.
With rising consumer demand for natural products, a greener and cleaner technology, i.e., ultrasound-assisted extraction, has received immense attention given its effective and rapid isolation for nanocellulose compared to conventional methods. Nevertheless, the application of ultrasound on a commercial scale is limited due to the challenges associated with process optimization, high energy requirement, difficulty in equipment design and process scale-up, safety and regulatory issues. This review aims to narrow the research gap by placing the current research activities into perspectives and highlighting the diversified applications, significant roles, and potentials of ultrasound to ease future developments. In recent years, enhancements have been reported with ultrasound assistance, including a reduction in extraction duration, minimization of the reliance on harmful chemicals, and, most importantly, improved yield and properties of nanocellulose. An extensive review of the strengths and weaknesses of ultrasound-assisted treatments has also been considered. Essentially, the cavitation phenomena enhance the extraction efficiency through an increased mass transfer rate between the substrate and solvent due to the implosion of microbubbles. Optimization of process parameters such as ultrasonic intensity, duration, and frequency have indicated their significance for improved efficiency.
Poor aqueous solubility of bioactive compounds is becoming a pronounced challenge in the development of bioactive formulations. Numerous liposoluble compounds have very interesting biological activities, but their low water solubility, stability, and bioavailability restrict their applications. To overcome these limitations there is a need to use enabling delivering strategies, which often demand new carrier materials. Cellulose and its micro- and nanostructures are promising carriers with unique features. In this context, this review describes the fast-growing field of micro- and nanocellulose based delivery systems with a focus on the release of liposoluble bioactive compounds. The state of research on this field is reviewed in this article, which also covers the chemistry, preparation, properties, and applications of micro- and nanocellulose based delivery systems. Although there are promising perspectives for introducing these materials into various fields, aspects of safety and toxicity must be revealed and are discussed in this review. The impact of gastrointestinal conditions on the systems and on the bioavailability of the bioactive compounds are also addressed in this review. This article helps to unveil the whole panorama of micro- and nanocellulose as delivery systems for liposoluble compounds, showing that these represent a great promise in a wide range of applications.</p>
The inherent recalcitrance of lignocellulosic biomass is a significant barrier to efficient lignocellulosic biorefinery owing to its complex structure and the presence of inhibitory components, primarily lignin. Efficient biomass pretreatment strategies are crucial for fragmentation of lignocellulosic biocomponents, increasing the surface area and solubility of cellulose fibers, and removing or extracting lignin. Conventional pretreatment methods have several disadvantages, such as high operational costs, equipment corrosion, and the generation of toxic byproducts and effluents. In recent years, many emerging single-step, multi-step, and/or combined physicochemical pretreatment regimes have been developed, which are simpler in operation, more economical, and environmentally friendly. Furthermore, many of these combined physicochemical methods improve biomass bioaccessibility and effectively fractionate similar to 96 \% of lignocellulosic biocomponents into cellulose, hemicellulose, and lignin, thereby allowing for highly efficient lignocellulose bioconversion. This review critically discusses the emerging physicochemical pretreatment methods for efficient lignocellulose bioconversion for biofuel production to address the global energy crisis.
The second (lignocellulosic biomass and industrial wastes) and third (algal biomass) generation feedstocks gained substantial interest as a source of various value-added chemicals, produced by fermentation. Lactic acid is a valuable platform chemical with both traditional and newer applications in many industries. The successful fractionation, separation, and hydrolysis of lignocellulosic biomass result in sugars' rich raw material for lactic acid fermentation. This review paper aims to summarize the investigations and progress in the last 5 years in lactic acid production from inexpensive and renewable resources. Different aspects are discussed-the type of raw materials, pretreatment and detoxification methods, lactic acid-producers (bacteria, fungi, and yeasts), use of genetically manipulated microorganisms, separation techniques, different approaches of process organization, as well as main challenges, and possible solutions for process optimization.
Ceramics are considered one of the greatest and earliest most useful successes of humankind. However, ceramics can be highly damaging to natural and social systems during their lifecycle, from material extraction to waste handling. For example, each year in the EU, the manufacture of ceramics (e.g., refractories, wall and floor tiles and bricks and roof tile) emit 19 Mt CO2, while globally, bricks manufacturing is responsible for 2.7\% of carbon emissions annually. This critical and systematic review seeks to identify alternatives to mitigate the climate effects of ceramics products and processes to make their lifecycle more sustainable. This article reviews 324 studies to answer the following questions: what are the main determinants of energy and carbon emissions emerging from the ceramics industry? What benefits will this industry amass from adopting more low-carbon processes in manufacturing their products, and what barriers will need to be tackled? We employ a sociotechnical approach to answer these questions, identify barriers to decarbonise the ceramics industry, and present promising avenues for future research. In doing so, we show that environmental and energy challenges associated with the ceramics industry are not just limited to the manufacturing stage but also relate to the extraction of raw materials, waste disposal, and landfilling.
Fe3O4-Arg was selected as the optimal carrier due to its high activity recovery of immobilized cells in the preparation of Fe3O4-Arg-Cells. The optimal immobilization conditions for the preparation of Fe3O4-Arg-Cells were 30 degrees C, 4 h, pH 7, and 3 g dry yeast. The activity recovery of immobilized cells reached 76.8 \%. For a batch reduction in a shaker in an alternating magnetic field, Fe3O4-Arg-Cells were used as a catalyst to gain ethyl (R)-4-chloro-3-hydroxybutyrate ((R)-CHBE). For further improvement in reduction productivity, a continuous reduction in the magnetic fluidized bed reactor system (MFBRS) was completed. Under their optimal transformation conditions, it took 24 h for Fe3O4-Arg-Cells to complete the conversion of ethyl 4-chloro-3-oxobutanoate (COBE) (0.8553 mol/L) in the shaker and only 8 h for the batch reduction in an alternating magnetic field. Continuous reduction in MFBRS provided new ideas for the efficient production of (R)-CHBE; 1.5882 mol/L (10 mL) of COBE can be completely converted in 6 h. The conversion and enantiomeric excess (e.e.) of (R)-CHBE were 100 \% and above 99.9 \% respectively, in the three reaction systems mentioned above.
To reduce greenhouse emissions, the utilization of biomass is a proficient path for producing power and its impact on accumulative carbon footprint. Generation of power using biomass produces residue majorly in the form of ash. However, as electrical demand rises, the utilization of biomass as feedstock surges, resultantly the quantity of ash from power plants increases. Production of the ash in biomass-fired power plants arise multiple problems exclusively handling of ash and its utilization. The continuous rise in ash quantity will challenge ash storing facilities while increasing management, transferring and disposal cost. Direct disposal to the land sites may also effects the soil nutrient and its structure. This review investigated the basic challenges in biomass ash production, environmental concerns and handling issues. Furthermore, the study explores the various opportunities in biomass ash utilization in conventional applications such as agriculture, construction, and cement industry. Moreover, the status and prospects of ash utilization in novel application such as nanotechnology in industrial catalysis and environmental applications have been well elucidated. Finally, the recommendations were also derived to pave the path for efficient utilization of biomass ash to improve the overall economy of the biomass operated power plants and sustainable development.
Lignocellulose represents the most abundant carbon-capturing substance that is convertible for biofuels and bioproduction. Although biomass pretreatments have been broadly applied to reduce lignocellulose recalcitrance for enhanced enzymatic saccharification, they mostly require strong conditions with potential secondary waste release. By classifying all major types of pretreatments that have been recently conducted with different sources of lignocellulose substrates, this study sorted out their distinct roles for wall polymer extraction and destruction, leading to the optimal pretreatments evaluated for cost-effective biomass enzymatic saccharification to maximize biofuel production. Notably, all undigestible lignocellulose residues are also aimed for effective conversion into value-added bioproduction. Meanwhile, desired pretreatments were proposed for the generation of highly -valuable nanomaterials such as cellulose nanocrystals, lignin nanoparticles, functional wood, carbon dots, porous and graphitic nanocarbons. Therefore, this article has proposed a novel strategy that integrates cost-effective and green-like pretreatments with desirable lignocellulose substrates for a full lignocellulose utiliza-tion with zero-biomass-waste liberation.
Lignin is a natural aromatic polymer of p-hydroxyphenylpropanoids with various biological activities. Noticeably, plants have made use of lignin as biocides to defend themselves from pathogen microbial invasions. Thus, the use of isolated lignin as environmentally benign antimicrobial is believed to be a promising high value approach for lignin valorization. On the other hand, as green and sustainable product of plant photosynthesis, lignin should be beneficial to reduce the carbon footprint of antimicrobial industry. There have been many reports that make use of lignin to prepare antimicrobials for different applications. However, lignin is highly heterogeneous polymers different in their monomers, linkages, molecular weight, and functional groups. The structure and property relationship, and the mechanism of action of lignin as antimicrobial remains ambiguous. To show light on these issues, we reviewed the publications on lignin chemistry, antimicrobial activity of lignin models and isolated lignin and associated mechanism of actions, approaches in synthesis of lignin with improved antimicrobial activity, and the applications of lignin as antimicrobial in different fields. Hopefully, this review will help and inspire researchers in the preparation of lignin antimicrobial for their applications.
The utilization of lignocellulosic feedstocks is the most promising, sustainable, and eco-friendly approach towards the production of polyhydroxyalkanoate since it entirely avoids the consumption of food crops. The use of these renewable and inexpensive feedstocks can make the production of polyhydroxyalkanoates affordable and facilitate the competitive commercialization of these carbon-neutral bio-based polyesters and their copolymers. Nevertheless, lignocellulosic biomass currently needs pretreatment to realize high sugar yields for the microbes to synthesize the polyhydroxyalkanoates. Steam pretreatment with dilute acids, followed by cellulase enzyme pretreatment, is a relatively practical approach to decompose these rigid biomasses into sugar monomers. However, the cost of commercial cellulase preparations continues to obstruct the large-scale economic conversion of lignocellulosic materials. Development of an eco-friendly consolidated bioprocessing system employing thermophiles for the single-step conversion of lignocellulose to polyhydroxyalkanoate, which excludes pretreatment and enzyme addition steps, and could be operative at low capital investment, would be an important breakthrough for the bioplastic industry. The scope of the present review is to highlight the significant and valuable research and development activities made in recent years to biosynthesize polyhydroxyalkanoates utilizing low-cost lignocellulosic biomass as the potential raw material. The future opportunity for the economical production of polyhydroxyalkanoate through unprocessed lignocellulosic biomass using thermophiles is also discussed. (C) 2020 Elsevier Ltd. All rights reserved.
Recycling of construction and demolition waste in the concrete is considered a sustainable way However, recycled aggregates (RA) with inferior properties are produced after recycling as compared to natural aggregates. This study aims to improve the performance of RA by utilizing different treatment methods and to evaluate the properties of the resulting recycled aggregate concrete (RAC). For this purpose, five different treatment techniques of RA, such as carbonation, acetic acid immersion, acetic acid immersion with mechanical rubbing, acetic acid immersion with carbonation and lime immersion with carbonation are adopted during the study. Different mechanical tests are performed to investigate the effect of different RA treatment techniques on the mechanical properties of RAC with treated and untreated RA. Increase in split tensile strength and flexural strength along with improved stress-strain behavior of RAC is observed for treated RA as compared to untreated RA. The stress-strain behavior of RAC having RA treated through acetic acid immersion with mechanical rubbing and lime immersion with carbonation is observed very close to the stress-strain curves of natural aggregate concrete reflecting the positive impact of these RA treatment techniques on the performance of RAC. Moreover, empirical relations to predict different mechanical properties and stress-strain model of RAC with both treated and untreated RA are also developed in this work. A comparative study of the existing and proposed models with the test results indicates that the proposed relations and model can effectively predict the mechanical behavior of RAC with both treated and untreated RA.
Bioremediation of contaminated groundwater or soil is currently the cheapest and the least harmful method of removing xenobiotics from the environment. Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes, reduces their costs, and also allows for the multiple use of biocatalysts. Among the developed methods of immobilization, adsorption on the surface is the most common method in bioremediation, due to the simplicity of the procedure and its non-toxicity. The choice of carrier is an essential element for successful bioremediation. It is also important to consider the type of process (in situ or ex situ), type of pollution, and properties of immobilized microorganisms. For these reasons, the article summarizes recent scientific reports about the use of natural carriers in bioremediation, including efficiency, the impact of the carrier on microorganisms and contamination, and the nature of the conducted research. (C) 2016 Pontificia Universidad Catolica de Valparaiso. Production and hosting by Elsevier B.V. All rights reserved.
Lignocelluloses' pretreatment is targeted for the improvement of hydrolysis of their carbohydrates, i.e., cellulose and hemicelluloses. Modification of the hardheaded structure of lignocelluloses is a fundamental stair in biofuels and biochemicals production. The high crystalline configurations of cellulose embed with hemicelluloses and lignin, give rise to recalcitrance structure. Second-generation biofuel production processes, using lignocellulosic biomass as a feedstock, is based on a three-stage process, including pretreatment, enzymatic hydrolysis, and fermentation. The pretreatment stage is the most critical, influencing, costly stage. The perfect pretreatment process is designated to provide minimum cellulosic crystallinity with remarkable low lignin content as well as inhibitory compounds through a sustainable economical process. In the present review, advances in lignocellulosic pretreatment technologies for biofuels production are reviewed and critically discussed. The article further discusses the pros and cons of the various pretreatment methodologies as well as addresses the role and impact of different process parameters associated with the pretreatment process.
In an attempt to improve the sustainability of construction and reduce portland cement (PC) consumption, the use of supplementary cementitious materials (SCMs), such as ground granulated blast-furnace slag (GGBS), has become a common practice. On the other hand, to increase the durability of cementitious composites, various internal curing agents, including superabsorbent polymers (SAPs), are often used. Owing to their high capacity to absorb, retain, and release water, SAPs can provide additional water for continuous hydration and lead to more homogeneous microstructures. They are usually neutralized by alkali metals (sodium and potassium) to increase their absorption capacities and keep them stable in PC cementitious matrices. This article discusses the applicability of SAPs in blended systems. It aims to evaluate the effect of GGBS on the water absorption capacity and stability of three partially neutralized SAPs. SAP swelling capacity and kinetics of absorption, pH of binder solutions over time, and the mechanical properties of PC-GGBS matrices are analyzed. The results show that alkali content of up to 4\% by weight leads to a GGBS system that is comparable to a stable PC system. Above this limit, SAP degradation starts to take place due to ion exchange with GGBS solution components, resulting in lower compressive strength compared to PC matrices. Thus, the excess of alkalis in SAP networks plays an important role in GGBS aqueous solutions. (C) 2018 American Society of Civil Engineers.
The production cost and viscosity of certain ionic liquids (ILs) are among the major factors preventing the establishment of economically viable IL-based biomass pretreatment technologies. Recently, mixtures of an IL with an organic solvent have been proposed for cellulose processing and biomass pretreatment. Dimethyl sulfoxide (DMSO) is an inexpensive organic solvent that is industrially produced from lignin, a byproduct of the pulping process. We carry out a mechanistic study of DMSO-assisted IL pretreatment of switchgrass. The physical structures of biomass samples are studied by X-ray diffraction (XRD), N-2 adsorption analysis, and small angle neutron scattering (SANS). Both dry and aqueous suspensions of biomass samples are measured by SANS which provides unique information on biomass pretreatment. A mixture of 42 wt \% {[
The demand for resources to supply the world's energy needs has been increasing day by day; agricultural processing wastes and residues generated by the industrial sector could be transformed into energy, mitigating environmental impact. Rising concern about environmental issues has been increasing, which, in turn, presses governments and companies to develop policies and solutions to solve these problems. In this context, the industrial symbiosis aims to reach sustainability by closing productive cycles, where the residues from an industry are the raw material for others. Agri-food residues are important sources of compounds with commercial interest that could be recovered both to decrease the volume of residues generated, and also to improve the economic viability of processes, by producing added value products. For this purpose, several applications of the supercritical technology to add value to agri-food residues through both extraction of high value-added compounds and hydrolysis of lignocellulosic biomass to produce fermentable sugars are presented. (C) 2014 Elsevier B.V. All rights reserved.
It is essential to valorize waste biomass and promote a circular economy for realizing sustainability and decarbonization goals. In this review, we specifically focus on anaerobic digestion (AD) intensified via hydrodynamic cavitation (HC) and modeling as an effective biomass valorization strategy. AD is known to generate renewable energy (biogas) and fertilizer (digestate) and is therefore aligned with the circular economy framework and has the potential to decarbonize the transportation, energy, and heat sectors, which contribute a major share to the current global carbon emissions. The AD-based pathway, though robust, has key challenges such as poor carbon conversion and subpar biogas yields coupled with long residence times. This is mainly due to the recalcitrance offered by the feedstock. HC-based biomass pretreatment is critically reviewed here as a promising AD intensification strategy to overcome this recalcitrance. HC devices and their key aspects of design and scale-up are discussed. Vortex-based HC devices were found to be superior to conventional linear flow HC devices in terms of pretreatment performance and ease of scale up. The use of reaction engineering models of AD for overall optimization of biomass valorization is also discussed. The need for developing an intermediate modeling approach between empirical models and complex biochemical pathway-based models is highlighted. Such an intermediate approach requires simple biomethane potential (BMP) measurements for obtaining essential model parameters. With such parameters obtained from BMP data, the model was found to be useful for simulating and optimizing performance of AD. A prospective AD-based biorefinery is briefly discussed with multiple allied valorization pathways. This review will be useful to researchers and practicing engineers for realizing effective valorization of waste biomass.
Lignocellulosic biomass (LCB) is expected to play a significant role in achieving the goal of biomass-to-bioenergy conversion due to its wide distribution and low price. Acidogenic dark fermentation of LCB is a promising approach to the sustainable production of biohydrogen (bioH(2)) from this valuable substrate. Because of its inherent recalcitrance, LCB requires pretreatment to increase its digestibility and enable its improved utilization. Intense thermochemical pretreatments solubilize the lignin and hemicellulose and lead to the formation of a variety of inhibitory byproducts, such as short-chain carboxylic acids, furfural, 5-hydroxymethylfurfural (5-HMF), vanillin, and syringaldehyde, which interfere with the physiological and metabolic functions of dark fermentative microbiota, thus inhibiting bioH(2) production. To offset the negative impacts of these inhibitors on bioH(2) production, approaches to detoxify lignocellulosic hydrolysates have been considered. This review comprehensively discusses the generation of lignocellulosic inhibitory byproducts in commonly used, contemporary pretreatment regimens and their inhibitory effects on dark fermentative H-2 production. Furthermore, the mechanisms of inhibiting H-2 producing bacteria and their effects on bacterial community dynamics in mixed cultures are reviewed. State-of-the-art strategies for detoxifying pretreated LCB are discussed. The selection of desirable alternative lignocellulose pretreatment strategies that produce less or no inhibitory byproducts are highlighted. Finally, this review discusses the economic aspects of bioH(2) production from LCB, considering the pretreatment and detoxification process. Given the limitations of previous studies, future research for developing cost-effective strategies to overcome byproduct inhibition during dark fermentation of pretreated LCB are suggested.
Biopolymer-based flocculants have become a potential substitute for inorganic coagulants and synthetic organic flocculants due to their wide natural reserves, environmental friendliness, easy natural degradation, and high material safety. In recent years, with more and more attention to clean technologies, a lot of researches on the modification and application of biopolymer-based flocculants have been carried out. The present paper reviews the latest important information about the base materials of biopolymer-based flocculants, including chitosan, starch, cellulose, and lignin etc. This review also highlights the various modification methods of these base materials according to reaction types in detail. Via the recent researches, the flocculation mechanisms of biopolymer-based flocculants, such as adsorption, bridging, charge neutralization, net trapping, and sweeping, as well as, some other special mechanisms are comprehensively summarized. This paper also focuses on the water treatment conditions, the removal efficiency, and advantages of biopolymer-based flocculants in applications. Further, this review sheds light on the future perspectives of biopolymer-based flocculants, which may make progress in the sources of base materials, modification processes, multi-function, and deepening application researches. We believe that this review can guide the further researches and developments of biopolymer-based flocculants in the future, to develop them with a higher efficiency, a lower cost, more safety, and multi-function for more diversified applications.
Flavour and fragrance compounds are extremely important for food, feed, cosmetic and pharmaceutical industries. In the last decades, due to the consumer's increased trend towards natural products, a great interest in natural aroma compounds has arisen to the detriment of chemically synthesised ones. Recently, solid state fermentation (SSF) has been applied in the production of many metabolites. Aroma compounds can be produced by SSF with a higher yield compared to submerged fermentation (SmF). In SSF processes, aroma compounds can be produced in the solid matrix or in the headspace, but they can be lost or stripped when aeration is required. This review focuses on the production of aroma compounds by SSF processes with a special highlight on in situ systems to recover the volatiles released in the gaseous phase and stripped due to aeration. Following a brief presentation of specificities of SSF processes concerning the choice of microorganisms and the solid matrix used for the production of aroma compounds, bioreactor aspects, factors affecting production of aroma compounds and in situ gas phase aroma recovery systems in aerated SSF bioreactors are discussed.
Lignocellulose, one of the most abundant renewable sources of sugar, can be converted into bioenergy through hydrolysis of cellulose and hemicellulose. Due to its renewability and availability in large quantities, bioenergy is considered as a possible alternative to fossil energy and attracts the attention of the world with increased concerns about environmental protection and energy crisis. The depolymerization of cellulosic substrate to monomer is the rate-limiting step in the bioconversion of lignocellulose by cellulolytic microbes. Cellulosome, a multienzyme complex from anaerobic cellulolytic bacteria, can efficiently degrade the cellulosic substrates. Previous studies have shown that the reconstitution of cellulosome in vitro and its heterologous expression or display on the cell surface can help to solve the low yield problem of cellulosome in cellulolytic bacteria. This paper reviews the research progress in the reconstitution of cellulosome as well as its application in biorefinery, including the construction of cellulosome as well as different methods for cellulosome reconstitution and its surface display. This review will promote the understanding of cellulosome and its reconstitution.
Conventional supplementary cementitious materials (SCMs), such as blast furnace slags or fly ashes, have been used for many decades, and a large body of knowledge has been collected regarding their compositional make-up and their impacts on cement hydration and concrete properties. This accumulated empirical experience can provide a solid, confident base to go beyond the status quo and develop a new generation of low-clinker cements composed of new types and combinations of SCMs. The need for new sources of SCMs has never been greater, as supplies of traditional SCMs are becoming restricted, and the demand for SCMs to reduce CO2 emissions from concrete production is increasing. In this paper, recent research on emerging SCM sources is reviewed, along with new developments in characterizing and qualifying SCMs for use and improved knowledge of SCMs on long-term concrete performance and durability.
Biomass hydrolysis extracts, particularly sugars and other useful derivatives, are important products for further conversion to produce biofuels. The past 2 decades have witnessed significant research and development activities using hot-compressed water for the hydrolysis and conversion of cellulose, hemicellulose, and lignocellulosic biomass materials. This paper summarizes the decomposition mechanisms and hydrolysis products of these materials under various conditions in hot-compressed water. Key factors determining hydrolysis behavior in hot-compressed water are also discussed. Comparisons are made between hydrolysis in hot-compressed water and hydrolysis using other technologies, including acid hydrolysis, alkaline hydrolysis, and enzymatic hydrolysis. Advantages, disadvantages, typical operation conditions, products properties, and applicability are summarized. Key research issues on hydrolysis in hot-compressed water are identified, and future research prospects to further improve the technology are discussed.
In the upcoming years, the world will face societal challenges arising, in particular, from the impact of climate change and the inefficient use of natural resources, in addition to an exponential growth of the world population, which according to the United Nations (UN) estimations will be 9.8 billion in 2050. This increasing trend requires optimized management of natural resources with the use of value-added waste and a significant reduction in food loss and food waste. Moreover, the recent pandemic situation, COVID-19, has contributed indisputably. Along with the agri-food supply chain, several amounts of waste or by-products are generated. In most cases, these biomass wastes cause serious environmental concerns and high costs to enterprises. The valorisation of the agri-food loss and food industry wastes emerged as a useful strategy to produce certain value-added compounds with several potential applications, namely in the food, health, pharmaceutical, cosmetic, and environmental fields. Therefore, in this review, some of the crucial sustainable challenges with impacts on the valorisation of agri-food loss/wastes and by-products are discussed and identified, in addition to several opportunities, trends and innovations. Potential applications and usages of the most important compounds found in food loss/waste will be highlighted, with a focus on the food industry, pharmaceutical industry, and the environment.
The xylan richness and comparatively lower extractives and ash, make the corncob lignocellulose an excellent source for many biorefinery products and objectives. The unique packing of lignocellulose material in corncob makes it susceptible to different pretreatment approaches that are less effective on other types of biomass feedstocks. More specifically, after pretreating corncob, up to 99\% delignification, 100\% hemicellulose solubi-lization, and around 95\% cellulose recovery can be achieved. Accordingly, corncob-derived chemical platforms have found many applications ranging from conventional use to newer products like supercapacitors. Platform sugars and ethanol have been the major products derived from corncob's cellulose and hemicellulose, whereas the production of xylooligosaccharides is the second most reported objective. Corncob lignin is mostly valorized for its phenols. Traditional and emerging pretreatment approaches, were reported, and in some reports, corncob-lignocellulose is valorized without a pretreatment. The data reported over the past fifty years on the corncob pretreatment in the SCOPUS database was compiled and analyzed throughout this review. The efficiency of different pretreatment methodologies and their effect on downstream yields were compared in detail.
In this study, biomass-hydrolysate was used for enhancing the bioreduction of ethyl 4-chloro-3-oxobutanoate (COBE). Firstly, dilute alkalic salt pretreatment was attempted to pretreat bamboo shoot shell (BSS). It was found that enzymatic in situ hydrolysis of 20-50 g/L BSS pretreated with dilute alkalic salts (0.4\% Na2CO3, 0.032\% Na2S) at 7.5\% sulfidity by autoclaving at 110 degrees C for 40 min gave sugar yields at 59.9\%-73.5\%. Moreover, linear relationships were corrected on solid recovery-total delignification-sugar yield. In BSS-hydrolysates, xylose and glucose could promote the reductase activity of recombinant E. coli CCZU-A13. Compared with glucose, hydrolysate could increase the reductase activity by 1.35-folds. Furthermore, the cyclohexane-hydrolysate (10: 90, v/v) biphasic media containing ethylene diamine tetraacetic acid (EDTA, 40 mM) and L-glutamine (150 mM) was built for the effective biosynthesis of ethyl (R)-4-chloro-3-hydroxybutanoate {[
Lignocellulosic biomass is inevitably subject to fractionation and depolymerization processes for enhanced selectivity toward specific products, in most cases prior to catalytic upgrading of the three main fractions-cellulose, hemicellulose, and lignin. Among the developed pretreatment techniques, CO2-assisted biomass processing exhibits some unique advantages such as the lowest critical temperature (31.0 degrees C) with moderate critical pressure, low cost, nontoxicity, nonflammability, ready availability, and the addition of acidity, alongside easy recovery by pressure release. This Review showcases progress in the study of sub- or supercritical CO2-mediated thermal processing of lignocellulosic biomass-the key pre-step for downstream conversion processes. The auxo-action of CO2 in biomass pretreatment and fractionation, along with the involved variables, direct degradation of untreated biomass in CO2 by gasification, pyrolysis, and liquefaction with relevant conversion mechanisms, and CO2-enabled depolymerization of lignocellulosic fractions with representative reaction pathways are summarized. Moreover, future prospects for the practical application of CO2-assisted up- and downstream biomass-to-bioproduct conversion are also briefly discussed.
The use of agro-industrial residue in new processes has encouraged the development of biotechnological strategies to obtain biomolecules. Lignocellulosic materials are rich in xylan and can be used as an alternative and inexpensive source for xylooligosaccharide (XOS) production, contributing to the sustainable generation of products with high added-value. This article provides an overview of recent methodological strategies for XOS production, their health benefits as prebiotics, purification, and technological properties for industrial application. Classified as non-digestible, XOS are prebiotics and can be used as functional foods, promoting health benefits. The main advantages of XOS include the selective stimulation of beneficial microorganisms, the suppression of pathogenic bacteria and reduction of toxic compounds from the metabolism. XOS are produced from a wide diversity of lignocellulosic materials by chemical, physical and enzymatic methods, or by a combination of them. Physicochemical methods can generate undesirable byproducts, and/or a large amount of monosaccharides, and result in a more difficult purification, while enzymatic hydrolysis allows milder process conditions because the reactions are specific and less pollutant residues are generated. Technological and nutritional approaches for XOS production which allow their use in different food and pharmaceutical products, and which stimulate the dissemination of researches in other technological areas, have also been discussed.
Since the introduction of ionic liquids (IL) in 1914, there has been a growing interest in this class of materials, because of their unique properties. Ionic liquids are organic salts, melting below 100 degrees C, and are generally non-volatile and nonflammable. By combination of different anions and cations, a large number of ionic liquids can be synthesized. The extraordinary characteristics of ILs and the possibility of synthesizing large number of ILs make them as an appropriate medium for various chemical processes and applications. In this review, first, we give a brief overview on IL important physical properties, and then we look into different IL applications, considering recent studies and findings and the future prospects of using IL in each application. This review gives a reader a complete knowledge about various ILs application all together. In addition, it reveals the areas of application which will grow in future and can gain industrial importance. ILs applications in separation processes, lignocelluloses pretreatment, enhanced oil recovery (EOR), biocatalytic reactions, lubrication and electrochemistry are discussed. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
This review provides an overview of the environmental impacts of combustion-based electricity generation technologies from six different energy sources, hard coal, brown coal, natural gas, diesel, landfill gas, and wood biomass, using the compiled information from life cycle assessment (LCA) studies. Hard coal has the highest global warming and ecotoxicity impacts, while brown coal and diesel both have high impacts in three out of 10 impact categories. Energy recovery from landfills gas exhibits a great potential to reduce the adverse impacts of landfills without the energy recovery although the level of reduction depends on the energy recovery technologies. The reduction potential of wood biomass-based electricity shows the variability affected by the efficiency of electricity generation and transport distance of the biomass. The application of carbon capture and storage (CCS) technologies to current power generation systems demonstrates great reduction potential, particularly in global warming impact with the extent of reduction varying with the applied CCS technologies. This study points out the necessity for standardization of the LCA method for a better comparison of impact assessment results for different fuel sources. An integrated method of LCA with a geographic information system (GIS) is suggested to understand the spatial variability of the impacts of power stations and to investigate the synergetic impacts that could be induced by the close geographical proximity of power stations.
Utilization of microbial oil for biodiesel production has gained growing interest due to the increase in prices and the shortage of the oils and fats traditionally used in biodiesel production. However, it is still in the laboratory study stage due to the high cost of production. Employing organic wastes as raw materials to grow heterotrophic oleaginous microorganisms for further lipid production to produce biodiesel has been predicted to be a promising method for reducing costs. However, there are many obstacles including the low biodegradability of organic wastes, low lipid accumulation capacity of heterotrophic oleaginous microorganisms while using organic wastes, a great dependence on a high-energy consumption approach for biomass harvesting, utilization of toxic organic solvents for lipid extraction, and large amount of methanol required in trans-esterification and in-situ trans-esterifications. Ultra-sonication as a green technology has been extensively utilized to enhance bio-product production from organic wastes. In this article, ultra-sonication applications in biodiesel production steps with heterotrophic oleaginous microorganisms have been reviewed, and its impact, potential, and limitations on the process have been discussed.
The Construction industry can act as a major receptor for different kinds of agro-industrial and municipal wastes due to the high demand for construction materials. Therefore, various researchers have conducted studies on recycling and reuse potential of solid wastes coming from different sources. This summary reviews the wide range of investigations (1998-2019), which have explored the addition of many types of fluxing waste into fired clay bricks. The current study offers a comprehensive guideline on the influence of fluxing oxides on production (molding pressure, soaking time and firing temperature), physical properties (water absorption, bulk density, firing shrinkage) and mechanical properties (compressive and flexural strength) of clay bricks. The optimum amounts of different wastes for effective waste usage in brick fabrication were extracted from experimental results of a large database. Optimization was also done analytically by applying the multi-criteria decision-making technique considering shaping method, physical and mechanical properties, simultaneously. It is summarized that incorporation of fluxing waste benefits the manufacturing process by optimizing plasticity and reducing firing temperature through early sintering. In addition, it also enhances the physical and mechanical properties of bricks within the optimum replacement levels. The outcomes of this work may guide to establish codes and standardize fluxing waste incorporation in the manufacturing of bricks.
Lignin, an aromatic polymer found in plants, has been studied for years in many biological fields. Initially, when biofuel was produced from lignocellulosic biomass, lignin was regarded as waste generated by the biorefinery and had to be removed, because of its inhibitory effects on fermentative bacteria. Although it has since proven to be a natural resource for bio-products with considerable potential, its utilization is confined by its complex structure. Hence, the microbial degradation of lignin has attracted researchers' interest to overcome this problem. From this perspective, the studies have primarily focused on fungal systems, such as extracellular peroxidase and laccase from white- and brown-rot fungi. However, recent reports have suggested that bacteria play an increasing role in breaking down lignin. This paper, therefore, reviews the role of bacteria in lignin and lignin-related research. Several reports on bacterial species in soil that can degrade lignin and their enzymes are included. In addition, a cellulolytic anaerobic bacterium capable of solubilizing lignin and carbohydrate simultaneously has recently been identified, even though the enzyme involved has not been discovered yet. The assimilation of lignin-derived small molecules and their conversion to renewable chemicals by bacteria, such as muconic acid and polyhydroxyalkanoates, including genetic modification to enhance their capability was discussed. This review also covers the indirect use of bacteria for lignin degradation, which is concerned with whole-cell biosensors designed to detect the aromatic chemicals released from lignin transformation.
Biohydrogen production from dark fermentation of lignocellulosic materials represents a huge potential in terms of renewable energy exploitation. However, the low hydrogen yield is currently hindering its development on industrial scale. This study reviewed various technologies that have been investigated for enhancing dark fermentative biohydrogen production. The pre-treatment technologies can be classified based on their applications as inoculum or substrates pre-treatment or they can be categorised into physical, chemical, physicochemical and biological based on the techniques used. From the different technologies reviewed, heat and acid pre-treatments are the most commonly studied technologies for both substrates and inoculum pre-treatment. Nevertheless, these two technologies need not necessarily be the most suitable since across different studies, a wide array of other emerging techniques as well as combined technologies have yielded positive findings. To date, there exists no perfect technology for either inoculum or substrate pre-treatment. Although the aim of inoculum pre-treatment is to suppress H2-consumers and enrich H-2-producers, many sporulating H-2-consumers survive the pre-treatment while some non-spore H-2-producers are inhibited. Besides, several inoculum pre-treatment techniques are not effective in the long run and repeated pre-treatment may be required for continuous suppression of H-2-consumers and sustained biohydrogen production. Furthermore, many technologies employed for substrates pre-treatment may yield inhibitory compounds that can eventually decrease biohydrogen production. Consequently, much research needs to be done to find out the best technology for both substrates and inoculum pre-treatment while also taking into consideration the energetic, economic and technical feasibility of implementing such a process on an industrial scale. (C) 2015 Elsevier Ltd. All rights reserved.
With world reserves of petroleum fast depleting, in recent years ethanol has emerged as most important alternative resource for liquid fuel and has generated a great deal of research interest in ethanol fermentation. Research on improving ethanol production has been accelerating for both ecological and economical reasons, primarily for its use as an alternative to petroleum based fuels. Field crops offer potential source of fuel, offering promise as large-scale energy and based on its genetic diversity, climatic adaptation, biomass and sugar production. Lignocellulosic biomass is the most abundant organic raw material in the world. Production of ethanol from renewable lignocellulosic resources may improve energy availability, decrease air pollution and diminish atmospheric CO2 accumulation. The aim of the present review is to highlight on major agricultural, industrial and urban waste, which could be used for ethanol production in an ecofriendly and profitable manner. Primarily, the utilization of these wastes for ethanol production will reduce dependency on foreign oil and secondly, this will remove disposal problem of wastes and make environment safe from pollution. (c) 2006 Elsevier B.V. All rights reserved.
The high dependence on crude oil for energy utilization leads to a necessity of finding alternative sustainable resources. Solvents are often employed in valorizing the biomass into bioproducts and other value-added chemicals during treatment stages. Unfortunately, despite the effectiveness of conventional solvents, hindrances such as expensive solvents, unfavourable environmental ramifications, and complicated downstream separation systems often occur. Therefore, the scientific community has been actively investigating more costeffective, environmentally friendly alternatives and possess the excellent dissolving capability for biomass processing. Generally, `green' solvents are attractive due to their low toxicity, economic value, and biodegradability. Nonetheless, green solvents are not without disadvantages due to their complicated product recovery, recyclability, and high operational cost. This review summarizes and evaluates the recent contributions, including potential advantages, challenges, and drawbacks of green solvents, namely ionic liquids, deep eutectic solvents, water, biomass-derived solvents and carbon dioxide in transforming the lignocellulosic biomass into high-value products. Moreover, research opportunities for future developments and potential upscale implementation of green solvents are also critically discussed.
The efficient and sustainable disposal or value addition of waste plastic has of major importance. Recent studies on the char produced via pyrolysis have demonstrated that it is a valuable additive with multiple applications ranging from soil and water amendment, improving agricultural yield, supercapacitors, fuel cells, and in sup-port/catalysts, sustainable chemistry, and carbon sequestration. Thus, it is essential to ensure the quality and efficacy of biochar produced from any combination of feedstock and process to ensure maximum benefits. However, very few studies have focussed on techniques or process parameters to optimize biochar yield. This study aims to review pyrolysis techniques, reactor types, and pyrolysis parameters to identify the process pa-rameters that could enhance the generation of biochar from co-pyrolysis of plastic and biomass feedstock. This review discusses biochar production techniques, the mechanism of pyrolysis technology, pyrolysis types, and the reactor types. This is followed by a review of the factors that can be used to optimize biochar production. Accordingly, the review identified temperature, heating rate, reactor bed height and type, residence time, pressure, feedstock type and blending ratio of feedstock as the determinants that had the highest influence on the yield, stability, and carbon content of biochar. Most importantly, the technology readiness level (TRL) of biomass pyrolysis, plastic pyrolysis and co-pyrolysis of biomass and plastic is discussed. The review necessitates further studies on these parameters to ascertain the accuracy of optimization that can be achieved by configuring py-rolysis processes to biochar production.
Lignocellulosic biomass is recognized as potential sustainable source for production of power, biofuels and variety of commodity chemicals which would potentially add economic value to biomass. Recalcitrance nature of biomass is largely responsible for the high cost of its conversion. Therefore, it is necessary to introduce some cost effective pretreatment processes to make the biomass polysaccharides easily amenable to enzymatic attack to release mixed fermentable sugars. Advancement in systemic biology can provide new tools for the development of such biocatalysts for sustainable production of commodity chemicals from biomass. Integration of functional genomics and system biology approaches may generate efficient microbial systems with new metabolic routes for production of commodity chemicals. This paper provides an overview of the challenges that are faced by the processes converting lignocellulosic biomass to commodity chemicals. The critical factors involved in engineering new microbial biocatalysts are also discussed with more emphasis on commodity chemicals. (C) 2011 Elsevier Ltd. All rights reserved.
Ultrasound irradiation has been gaining increasing interests over the years to assist biological conversion of lignocellulosic biomass and waste materials to biofuels. As such, this study reviewed the different effects of sonication on pre-treatment of lignocellulosic biomass and waste materials prior to biofuel production. The mechanisms of ultrasound irradiation as a pre-treatment technique were initially described and the impacts of sonication on disruption of lignocellulosic materials, alteration of the crystalline lattice structure of cellulose molecules, solubilisation of organic matter, reducing sugar production and enzymatic hydrolysis were then reviewed. Subsequently, the influences of ultrasound irradiation on bio-methane, bio-hydrogen and bio-ethanol production were re-evaluated, with most studies reporting enhanced biofuel production from anaerobic digestion or fermentation processes. Nonetheless, despite its positive impacts on biofuel production, sonication was found to be energetically inefficient based on the lab-scale studies reviewed. To conclude, this study reviewed some of the challenges of ultrasound irradiation for enhanced biofuel production while outlining some areas for further research.
Incineration industrial by-products can be used as supplementary cementitious materials (SCMs) to degrade the cement output, thereby reducing fossil-fuel combustion and contributing to the utilization and management of waste resources. This paper summarizes the state-of-the-art uses of incineration industrial by-products (coal ash, waste incineration ash, and biomass incineration ash), which are used as SCMs in partial cement replacement. It also summarizes alkali-activated by-products as cementitious materials that replace all cement with controlled low-strength material (CLSM). After introducing the general situation and physicochemical characteristics of these pozzolanic incineration ashes, the influences and mechanisms of the by-products on the performance of CLSM are summarized and analyzed. The discussions and analyses in this paper are expected to inspire further research and provide a basis for the sustainable development of CLSMs from incineration industrial by-products as cementitious materials.
The annual food and agricultural waste production reaches enormous numbers. Therefore, an increasing need to valorize produced wastes arises. Waste materials originating from the food and agricultural industry can be considered as functional materials with interesting properties and broad application potential. Moreover, using an appropriate magnetic modification, smart materials exhibiting a rapid response to an external magnetic field can be obtained. Such materials can be easily and selectively separated from desired environments. Magnetically responsive waste derivatives of biological origins have already been prepared and used as efficient biosorbents for the isolation and removal of both biologically active compounds and organic and inorganic pollutants and radionuclides, as biocompatible carriers for the immobilization of diverse types of (bio)molecules, cells, nano- and microparticles, or (bio)catalysts. Potential bactericidal, algicidal, or anti-biofilm properties of magnetic waste composites have also been tested. Furthermore, low cost and availability of waste biomaterials in larger amounts predetermine their utilization in large-scale processes.
This review covers the operating conditions for extracting top value-added chemicals, such as levulinic acid, lactic acid, succinic acid, vanillic acid, 3-hydroxypropionic acid, xylitol, 2,5-furandicarboxylic acid, 5-hydroxymethyl furfural, chitosan, 2,3-butanediol, and xylo-oligosaccharides, from common lignocellulosic biomass. Operating principles of novel extraction methods, beyond pretreatments, such as Soxhlet extraction, ultrasound-assisted extraction, and enzymatic extraction, are also presented and reviewed. Post extraction, high-value biochemicals need to be isolated, which is achieved through a combination of one or more isolation and purification steps. The operating principles, as well as a review of isolation methods, such as membrane filtration and liquid-liquid extraction and purification using preparative chromatography, are also discussed.
The second generation (2G) ethanol obtained from lignocellulosic biomass has been considered as a potential alternative source of energy for the transportation sector. However, the technologies to convert lignocellulose into fermentable sugars still face several challenges. One of the major challenges of this process is related to the cost of the cellulolytic enzymes. Thus, the development of bioprocesses for enzyme production and strategies to increase the final yield of the enzymatic hydrolysis reactions are required to ensure the economic feasibility of the biomass conversion process. In this review, it is discussed the progress related to fungal enzyme technology over the past few years with major emphasis on the biocatalysts needed for cellulose degradation as well as on cultivation strategies for the production of enzymes on-site. The potential of applying secretome analysis as a tool for the characterization of the enzymatic complexes and some limitations on the use of enzymatic cocktails in the saccharification step, such as the unproductive adsorption of enzymes onto lignin are also discussed in light of the recent literature.
Biochar is mainly used as a soil amendment and for carbon sequestration; while other applications such as environmental remediation may be equally important. Recently, different engineering methods have been developed and used to expand biochar's applications. A systematic literature review on the linkages between the production methods and applications of engineered biochar, therefore, is in critical need. In this work, the production and application prospects of engineered biochar are reviewed comprehensively based on the current literature. The application values and effect of engineered biochar in energy, environment, and agriculture are also expounded. Different from previous ones, this review is more focused on the unique properties and functions of various types of engineered biochars to explain their potential application, particularly environmental application. It not only summarizes recent advances in engineered biochar technology but also offers insights on new directions for development and research of engineered biochar in the future.
The indiscriminate use of fossil fuels has led to several challenges such as greenhouse gas emissions, environmental degradation, and energy security. Establishment of clean fuels is at the forefront of science and innovation in today's society to curb these problems. Dark fermentation (DF) is widely regarded as the most promising clean energy technology of the 21st century due to its desirable properties such as high energy content, its non-polluting features, its ability to use a broad spectrum of feedstocks and inoculum sources, as well as its ability to use mild fermentation conditions. In developing nations, this technology could be instrumental in establishing effective waste disposal systems while boosting the production of clean fuels. However, DF is still hindered by the low yields which stagnate its commercialization. This paper reviews the recent and emerging technologies that are gaining prominence in DF based on information that has been gathered from recent scientific publications. Herein, novel enhancement methods such as cell immobilization, nanotechnology, mathematical optimization tools, and technologies for biogas upgrading using renewable H-2 are comprehensively discussed. Furthermore, a section which discusses the potential of bioenergy in Sub-Saharan Africa including South Africa is included. Finally, scientific areas that need further research and development in DF process are also presented.
Organosolv fractionation (OF) is a promising method for lignocellulosic biomass biorefining to produce biofuels, biochemicals, and biomaterials. The fractionated polymeric components may be good feedstocks to produce bio-based materials such as green polymers via chemical or biological conversion. However, related work to specify the bio-based materials production via organosolv fractionation of lignocellulosic biomass is relatively scarce. In this work we have provided a comprehensive review of typical organosolv fractionation for isolating cellulose, hemicelluloses, and lignin, as well as the high value-added monomer chemicals and functional materials derived from the fractionated components and their potential applications developed in recent years, primarily including the modified cellulose fibers for polymer materials, cellulose nanocrystals (CNCs), polysaccharide-derived platform precursors for synthesis of bio-based polymers, lignin-derived dispersants, surfactants, carbon materials, and hemicellulose-derived functional materials, etc. This work suggests that organosolv fractionation of lignocellulosic biomass could be a good entry to biomass refinery for high value-added and functional materials production. However, there are still many challenges that should be overcome in terms of the fundamental, technical, and economic aspects for the organosolv fractionation process, formation of precursor compounds, synthesis of the bio-based materials, design of product properties and functions, and the integration of the entire process. (C) 2019 Society of Chemical Industry and John Wiley \& Sons, Ltd
Anaerobic digestion (AD) is a multipurpose technology. One of the AD outcomes is biogas that can be used to supply a local thermal demand, electricity generation or upgraded to fuel vehicle. Brazil has the largest potential for producing biogas, due to its extensive agroindustrial production plus the fact that the country has a population of over 210 million inhabitants. The Brazilian Association of Biogas and Biomethane (ABiogas) reports a potential biogas production of 41.4 billion m3 per year in the sugar-energy sector. However, less than 2\% of this is achieved, indicating that the biogas is still chemically, economically, and politically invisible. The current technologies for the production, purification and end-use of biogas/biomethane were reviewed and presented in the context of sugarcane biorefineries. One of the major findings has indicated a thermal efficiency of 85\% and a national grid surplus of 74-121 kWh.ton(-1) sugarcane when steam boilers connected to electricity generators are used. Alternatively, a quarter of the vinasse generated by a medium-size sugarcane mill (600 m(3) d(-1)) would be enough to supply the diesel consumption of on agricultural operations. The motivation of this review came from the fact that normally renewable energy does not reach its potential due to the lack of references on technological, regulatory and management in their productive arrangements: essential aspects to make them feasible. Therefore, it is expected to strengthen the panorama of research in the biogas system to properly fit with the current expansion and diversification of the Brazilian energy matrix.
Using biomass waste as supplementary cementing material (SCM) in concrete has attracted researchers' attention for efficient waste utilization and reducing cement demand. Sugarcane bagasse ash (SCBA) is one such example of biomass waste. It is an agricultural waste obtained when sugarcane bagasse from the sugar industry is used for power generation and disposed of in open-air dumping sites. Its waste disposal causes the generation of particulate matter, degrading air quality. In this study, the effect of processed SCBA as SCM in concrete has been investigated. The processing of the SCBA involved the removal of fibrous and carbon-containing particles by sieving followed by grinding. The SCBA was ground for 45 min until the surface area was comparable to that of cement and was then used for further characterization and incorporation into concrete. The 45 min grinding time resulted in 2.92 times higher pozzolanic reactivity of the SCBA. The SCBA was incorporated by replacing cement in different weight fractions (10\%, 20\%, 30\%, 40\%) in concrete. Test results showed that the concrete workability increased with SCBA incorporation, whereas the resulting concrete density was reduced. The results of the mechanical properties, including compressive sstrength and hardened density, were enhanced upon the cement replacement by SCBA. Concrete containing 30\% SCBA can be used for structural applications as its 28 days compressive strength was 21 MPa, which complies with ACI 318-16 specifications. Concrete resistance against scaling and leaching due to adverse effects of sulfuric and hydrochloric acid considerably increased with SCBA addition and was due to microstructure densification by secondary hydrates formation as lower portlandite content was detected by thermogravimetric analysis. Hence, SCBA processing increases its reactivity, as reflected by the improved mechanical properties and greater durability of SCBA-incorporated concrete.
Alkaline treatment with sodium hydroxide ( NaOH) is widely used as a pretreatment for enzymatic saccharification of lignocellulosic biomass. For efficient utilization of sugarcane bagasse components, multistep alkaline pretreatment is carried out to extract the useful components before enzymatic saccharification. Alkaline treatment with 1 M NaOH at room temperature led to the extraction of p-Coumaric acid, ferulic acid, hemicellulose and lignin. About 60\% of the hemicellulose and lignin was extracted by treatment for 82 h. The residue obtained after 82 h of treatment was further treated with 1 M NaOH at 105 degrees C to produce a residue having less lignin and more cellulose than that obtained by a single 105 degrees C NaOH treatment. The residue obtained after treatment at 105 degrees C was further treated with 1 M NaOH at 170 degrees C to produce a material with 94\% cellulose. This phenomenon is probably due to a decrease in the frequency of lignin condensation because multistep treatment has removed part of the lignin from the reaction system. Alkaline treatment at room temperature is effective in accelerating delignification during subsequent alkaline treatments and enables the extraction of aromatic carboxylic acids, arabinoxylan, and lignin without hydrolysis and thermal denaturation.
The pyrolytic behavior, kinetic, and thermodynamic parameters of raw and metal (Ni, Ru, and Fe) impregnated sugarcane bagasse were investigated and evaluated by fitting thermogravimetric data of 5, 10, 15, and 20 ?/min heating rates (beta) into isoconversional models (FWO, KAS, and Kissinger's). Nano-metals (size \~{
The utilization of sugarcane bagasse (SB) in fermentation requires pretreatment processes to render fermentable components available to microorganisms. Pretreatment by using ionic liquids (ILs) is considered promising but the high cost is an impediment in its adoption, therefore, a mixture of IL pretreated and untreated SB was utilized to obtain bacterial multienzyme under solid-state fermentation (SSF). Bacillus aestuarii UE25, a thermophilic strain was utilized for that purpose. Fermentation conditions were optimized by adopting a central composite design. The model showed a good correlation between the predicted and the experimental values for amylase, xylanase, endoglucanase, and beta-glucosidase. Volumetric and specific productivity of xylanase (4580 IU ml(-1) h(-1), 244.25 IU mg(-1) substrate, and 50 IU mg(-1) protein) were higher than the other enzymes. Changes in lignin content and reduced cellulose crystallinity due to IL pretreatment, followed by fermentation, were visualized by scanning electron microscopy, Fourier transform infrared spectroscopy, and Nuclear magnetic resonance. The strategy adopted by utilizing a mixture of IL pretreated and untreated SB under SSF proved promising to obtain high titers of different enzymes simultaneously. Since the bacterial strain used is thermophilic, therefore, the multienzyme can find its application in commercial processes which are carried out at high temperatures.
Geopolymer foam concrete is an advanced composite material having the capability to be used as a lightweight, sustainable and energy-efficient material in the construction industry, having better insulating properties. The unique characteristics like low thermal conductivity and lesser environmental impact have fascinated the researchers to develop these materials using industrial by-products. Therefore, this research work focusses on development of fly ash-based geopolymer foam concrete incorporating sugarcane bagasse ash. In this study, fly ash-sugarcane bagasse ash blends based geopolymer foam concrete was successfully synthesized using an alkali activator to solid ratio (0.25), sodium silicate to sodium hydroxide ratio (2.5/1) and 2\% of hydrogen peroxide (H2O2). The mixtures with varying proportions of fly ash and sugarcane bagasse ash (SCBA) were prepared and intumescent through hydrogen peroxide. The results revealed that the insulating behavior of the mixture increases with an increase in sugarcane bagasse ash content. The GFC-00 exhibited the maximum compressive strength of 4.5 MPa with bulk density of 1295 kg/m(3) and total percentage porosity of 42.4\%. The GFC-50 proved to be an optimized mixture with thermal conductivity of 0.243 W m(-1) k(-1) for bulk density of 859 kg/m(3) and total percentage porosity of 58.1\%. From the results, it is found that the fly ash-SCBA-based geopolymer foam concrete can be used as a lightweight insulating material in non-load-bearing applications, as per the international standards.
Techno-economic models for three plants in Queensland, Australia using thermochemical conversion of 10 tonnes per hour of sugarcane bagasse to liquid crude biofuels were developed. Thermochemical conversion was chosen to maximise yield from second-generation feedstock. The process models highlighted the differences in mass and energy flows of each process. Factory models were generated reflecting current methods in heat and material recovery. Liquefaction generated the highest amount of product per kg feed, followed by pyrolysis and gasification. Key parameters affecting plant economics were also highlighted. Based on net present values, the profitability was ranked as follows: pyrolysis > liquefaction > gasification. The plants were all sensitive to product price, thermochemical conversion ratio and refining conversion ratio, thereby affecting profitability the most. Conversion ratios sharply affect the minimum selling price of products, but attenuated by high product volumes. Varying tax rates and capital costs do not affect the minimum selling price as much as conversion ratios, therefore, incentives around improving conversion rates and increasing product volume are recommended. (C) 2019 Elsevier Ltd. All rights reserved.
This research work primarily focussed on the production of biochar from sugarcane bagasse through HTC followed by NaOH activation at inert atmosphere for removing SMX from water. The biochar was characterized for structural morphology and presence of functional groups. XRD and FTIR analysis confirmed that presence of aromatized graphitic structure accumulated with oxygenated functional groups are responsible for the elimination of SMX. SEM analysis portrayed the sphere-shaped structure of biochar with hydrophobic groups interior and hydrophilic groups exterior. BET isotherm revealed the active surface area equal to 1099 m(2)/g with high coverage of mesopores structure. P-zpc of adsorbent is evaluated to 6.5 stating that effective removal of SMX depends on ionization effects induced due to reaction medium. Kinetics study revealed the sorption of SMX followed chemical interaction pertaining to Elovich model. Isotherm studies revealed that Freundlich model fitted well stating heterogeneous mode of interaction. Immobilization of SMX on surface of ABC is due to charge assisted hydrogen bonding and pi-pi interaction with graphitized carbon, showing maximum sorption capacity of 400 mg/g through spontaneous reaction. The results suggested that HTC derived biochar had great adsorption affinity with respect to pH towards SMX and could be employed as an effective sorbent in cleaning water contaminants.
The objective of present study was to demonstrate efficient conversion of residual sugarcane bagasse by thermocatalytic reforming (TCR (R)) into fuels and high-value products in a laboratory scale 2 kg/h unit. None of the toxic or non-toxic chemicals and solvents was employed during the process, thus minimizing negative environmental effects. In addition, a detailed study on the composition of bio-oil using GC MS, FT-IR and on the properties of biochar using Raman spectroscopy, SEM, SEM-EDS, TEM, TEM-EDX and BET surface analyzer have been reported for the first time for TCR (R) process. At optimum operating parameters, similar to 57.0 wt\% gaseous products, 23.5 wt\% biochar, 15.5 wt\% aqueous phase and similar to 4 wt\% bio-oil were obtained. The hydrogen content and higher heating value (HHV) of the gaseous product were measured up to 37 vol\% and 16.40 MJ/kg, respectively. The bio-oil was naturally separable from liquid phase due to gravity without application of an extracting solvent. Moreover, the bio-oil had very low water (2.6 wt\%) and oxygen (10.2 wt\%) content as well as HHV of 32.11 MJ/kg. Furthermore, biochar produced from TCR (R) possessed excellent structural and morphological properties, thereby showing potential for several applications in catalysis, soil improvement and for various other purposes. The BET surface area and micropore surface area of biochar were measured 93.144 m(2)/g and 90.654 m(2)/g, respectively whereas, the t-plot micropore volume was measured 0.0487 cm(3)/g.
Cellulose is a most abundant natural biopolymer, however, the strong hydrogen bonding system makes cellulose hard to dissolve, limiting its further applications. In this study, an innovative cold plasma (CP) technology was used to modify cellulose from sugarcane (Saccharum officinarum) bagasse pulp. Dissolution, structure, and surface chemistry of cellulose before and after CP treatment were investigated. Results showed that the dissolution rate of cellulose after different CP treatment time (3-12 min) and operating voltage (40-70 kV) was significantly improved. Roughness, even holes (CP treatment 9 min with 50 kV) and breakage (CP treatment 9 min with 70 kV) were observed on the surface. The crystallinity index decreased from 62.31\% (control) to 60.88\% (CP treatment 3 min with 50 kV). The hydrogen bonding force was weakened and the peak intensity of C=O and C=O stretching vibration groups were enhanced. Therefore, CP-modified cellulose may be applied more in future, such as biological films for food future packaging.
The homogeneous chemical modification of sugarcane bagasse cellulose with succinic anhydride using 1-allyl-3-methylimidazolium chloride (AmimCl) ionic liquid as a reaction medium was studied. Parameters investigated included the molar ratio of succinic anhydride/anhydroglucose units in cellulose in a range from 2:1 to 14: 1, reaction time (from 30 to 160 min), and reaction temperature (between 60 and 110 degrees C). The succinylated cellulosic derivatives were prepared with a low degree of substitution (DS) ranging from 0.071 to 0.22. The results showed that the increase of reaction temperature, molar ratio of SA/AGIJ in cellulose, and reaction time led to an increase in DS of cellulose samples. The products were characterized by FT-IR and solid-state CP/MAS C-13 NMR spectroscopy, and thermal analysis. It was found that the crystallinity of the cellulose was completely disrupted in the ionic liquid system under the conditions given. The data also demonstrated that homogeneous modification of cellulose with succinic anhydride in AmimCl resulted in the production of cellulosic monoester. The thermal stability of the succinylated cellulose decreased upon chemical modification. (c) 2007 Elsevier Ltd. All rights reserved.
The addition of enzymes that are capable of degrading hemicellulose has a potential to reduce the need for commercial enzymes during biomass hydrolysis in the production of fermentable sugars. In this study, a high xylanase producing actinomycete strain (Kitasatospora sp. ID06-480) and the first ethyl ferulate producing actinomycete strain (Nonomuraea sp. ID06-094) were selected from 797 rare actinomycetes, respectively, which were isolated in Indonesia. The addition (30\%, v/v) of a crude enzyme supernatant from the selected strains in sugarcane bagasse hydrolysis with low-level loading (1 FPU/g-biomass) of Cellic (R) CTec2 enhanced both the released amount of glucose and reducing sugars. When the reaction with Ctec2 was combined with crude enzymes containing either xylanase or feruloyl esterase, high conversion yield of glucose from cellulose at 60.5\% could be achieved after 72h-saccharification.
Rice husk and sugarcane bagasse were chemically impregnated with ZnCl2 and carbonized at 700 degrees C in a large-scale rotary furnace. The activated carbons (ACs) obtained had BET surface area of 811 and 864 m(2)/g, respectively, and were essentially microporous. The adsorption of arsenic, humic acid, phenol and a municipal solid waste landfill leachate was examined. Both ACs showed the best adsorption behaviour towards phenol, removing around 80\% at the equilibrium time of 4 h. The adsorption isotherms for arsenic and humic acid were also favourable, although the maximum loadings achieved were lower than that of phenol. Finally. the rice husk AC showed 60\% and 70\% removal efficiency for colour and COD, respectively, when tested on a landfill leachate. (C) 2008 Elsevier B.V. All rights reserved.
This study reports high gravity fed-batch simultaneous saccharification and fermentation (FB-SSF) of sequen-tially pretreated sugarcane bagasse (SCB) for enhanced bioethanol by employing multiple inhibitor tolerant Kluyveromyces marxianus JKH5 C60. FB-SSF with intermittent feeding of SCB (total 20 \% solid loading) and enzyme (total dose of 20 FPU/g) at 6 and 12 h resulted in superior bioethanol production at 42 degrees C. Under optimized lab-scale FB-SSF, the maximum ethanol titer, efficiency and productivities were 73.4 +/- 1.2 g/L, 78 \% and 3.0 g/L/h, respectively, after 72 h in presence of inhibitors (acetic acid, furfural, and vanillin at 3, 1, and 1 g/ L, respectively). Furthermore, pentose rich dilute acid hydrolysate of SCB was subjected to fermentation by Pichia stipitis NCIM 3499, resulting in ethanol titer of 6.8 g/L. Overall ethanol yield during the developed process was 260.1 g/kg native SCB, which proves industrial potential of the developed bioethanol conversion process.
This study introduces a merlinoite synthesized from sugarcane bagasse ash (SBA) and kaolin and evaluates its application as an adsorbent to remove lead from wastewater. The synthesis was performed via the hydrothermal method, and optimal conditions were determined. The adsorption of Pb by merlinoite was also optimized. Determination of the Pb2+ remaining in the aqueous solution was determined by atomic absorption spectroscopy (AAS). Adsorption isotherms were mainly studied using the Langmuir and Freundlich models. The Langmuir model showed the highest consistency for Pb adsorption on merlinoite, yielding a high correlation coefficient (R-2) of 0.9997 and a maximum adsorption capacity (q(max)) of 322.58 mg/g. The kinetics of the adsorption process were best described by a pseudo-second-order model. Thermodynamic studies carried out at different temperatures established that the adsorption reaction was spontaneous and endothermic. The results of this study show that merlinoite synthesized from kaolinite and SBA is an excellent candidate for utilization as a high-performance adsorbent for lead removal from wastewater.
In this study, an efficient, reusable, and environmental catalytic system consisting of sugarcane bagasse (an agricultural and sugar mill waste material, SCB) and KI was applied to the cydoaddition of carbon dioxide (CO2) to epoxides or aziridines under mild conditions for the first correlated with the large quantities hydroxyl groups in SCB, which had a time. Their catalytic cycloaddition activities were found to be well synergetic effect with the halide anion of KI. The as-prepared catalytic system also exhibited excellent cycloaddition activities for various epoxide or aziridine substrates as well. Moreover, the catalyst could be recovered and reused multiple times without obvious loss in activity. The present method represents an integrated and ideal green process for the utilization of biomass and ``carbon neutral{''
Sugarcane bagasse is used as energy source in the sugar cane industry. An appropriate characterization of their physical and morphological properties is vitally important for their use in the gasification and combustion processes. This work makes a study of the size and shape distribution of the bagasse generated in a sugarcane mill based upon two important factors that influence their physical properties, such as aspect ratio (AR) and sphericity. The distribution of the grain sizes has been determined for the analyzed samples; the shapes of the particles has been determined by a manual method and through an image-analysis method, using the Image) software. It has been observed that sugarcane bagasse has a larger length than the other analyzed biomasses, with an almost similar width. The aspect ratio was between 2.14 and 5.5 for all the studied size ranges (9.5-0.15 mm). For particles with diameters smaller than 0.3 mm, the aspect ratio has a similar behavior to the other biomasses, with a reported value of 2.5. The determined sphericity was between 0.27 and 0.558, with a mean value of 0.397. (C) 2019 Published by Elsevier Ltd.
Sugarcane bagasse (SCB) was treated under mild alkaline conditions (solid:liquid ratio of 1:20 (w/v), 1.5\% NaOH (w/v), 60 degrees C, 6 h) to fractionate the lignocellulose in order to produce a typical mild alkaline extract from a lignocellulosic biomass. The solid residue was enriched in cellulose, while the SCB alkaline extract contained lignin and hemicelluloses, but also inorganic salts, five phenolic monomers and acetic acid. After concentration of the alkaline extract by evaporation, low pressure chromatography with water as eluent was performed to produce purified fractions. Two different strong acid cation (SAC) exchange resins were tested: one gel-type resin and one macroporous-type resin. The lignin and hemicelluloses were separated from the inorganic salts by the gel-type SAC exchange resin. On this resin, the phenolic monomers were partitioned regarding the presence or absence in their structure of a carboxyl group. On the macroporous-type SAC exchange resin, the largest sugar oligomers and lignin oligomers were obtained in a fraction free of inorganic salts, phenolic monomers and acetic acid.
Laccases are oxidative enzymes linked to biological degradation of lignin. The aim of this work was to evaluate the effect of inducers and different concentrations of nitrogen on production level of total laccase activity and pattern of laccase isoforms, produced in solid state fermentation of sugarcane bagasse by a selected strain of Pleurotus streams. The addition of yeast extract 5 g/L, copper sulfate 150 mu M and ferulic acid 2 mM provided highest enzymatic activity (167 U/g) and zymograms indicated the presence of six laccase isoforms (POXA1b, POXA3, POXC and three other isoforms). Results of protein identification by mass spectrometry confirmed the presence of POXC and POXA3 as the main isoenzymes, and also identified a glyoxal oxidase and three galactose oxidases. The fact that the isoenzyme POXA1b was not identified in the analyzed samples can be possibly explained by its sensitivity to protease degradation. (C) 2012 Elsevier Ltd. All rights reserved.
Sugarcane bagasse is used as a fuel in conventional bioethanol production, providing heat and power for the plant; therefore, the amount of surplus bagasse available for use as raw material for second generation bioethanol production is related to the energy consumption of the bioethanol production process. Pentoses and lignin, byproducts of the second generation bioethanol production process, may be used as fuels, increasing the amount of surplus bagasse. In this work, simulations of the integrated bioethanol production process from sugarcane, surplus bagasse and trash were carried out. Selected pre-treatment methods followed, or not, by a delignification step were evaluated. The amount of lignocellulosic materials available for hydrolysis in each configuration was calculated assuming that 50\% of sugarcane trash is recovered from the field. An economic risk analysis was carried out; the best results for the integrated first and second generation ethanol production process were obtained for steam explosion pretreatment, high solids loading for hydrolysis and 24-48 h hydrolysis. The second generation ethanol production process must be improved (e.g., decreasing required investment, improving yields and developing pentose fermentation to ethanol) in order for the integrated process to be more economically competitive.
BFS-MK-based alkali-activated materials are well established as an alternative for sustainable and green construction. This work aims to collaborate and encourage the use of biomass ashes, such as sugarcane bagasse ash (SCBA), as a precursor in alkali-activated materials (AAM). This ash is a rich source of aluminosilicate, which is a primary requirement for this application. In addition, this waste is still an environmental liability, especially in developing countries, and with a large volume of annual production. Thus, in this research, alkali-activated pastes (AA) were produced using sugarcane bagasse ash (SCBA), granulated blast furnace slag (BFS) and metakaolin (MK) as precursors. In addition, environmental gains were encouraged with energy savings, with no extra reburn or calcination steps in the SCBA. Thus, the precursors were characterized by laser granulometry, X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The pastes were produced by mixing the precursors with the activator, composed of a mixture of sodium hydroxide 8 mol/L and sodium silicate. Aiming to study the incorporation of SCBA, all samples have a precursor/activator ratio and a BFS/(BFS + MK) ratio constant of 0.6. The compressive strength analysis, FTIR, XRD, TGA, SEM and isothermal calorimetry analyses pointed out the occurrence of alkaline activation in all proposed samples for curing times of 7, 28 and 91 days. The sample GM0.6-BA0 (15\% SCBA) achieved the highest compressive strength among the samples proposed (117.7 MPa, at 91 days), along with a good development of strength throughout the curing days. Thus, this work presents the properties of alkaline-activated pastes using SCBA as a sustainable and alternative precursor, seeking to encourage the use of raw materials and alternative waste in civil construction.
In this study, we investigated the production of bioethanol from sugarcane bagasse (SCB) using an NH4OH-H2O2 pretreatment and simultaneous saccharification and co-fermentation (SScF). Response surface methodology and a 2(3) Box-Behnken design were used to evaluate the effect of different liquid mixture concentrations, liquid-to-solid ratios (LSRs) and pretreatment temperatures on the production of ethanol. The liquid mixture concentration and LSR significantly influenced the fermentation efficiency. Based on ridge max analysis, the following pretreatment conditions resulted in a fermentation efficiency of 95.79 +/- 0.01\%: liquid mixture concentration 53\%, LSR 28, and a temperature of 63A degrees C. A morphological analysis performed using scanning electron microscopy (SEM) and chemical characterization revealed that these pretreatment conditions were effective in disrupting the sugarcane fibers and removing lignin. Ethanol fermentation with the pretreated SCB using SScF in yeast SHY 07-1 resulted in an ethanol concentration of 14.65 +/- 0.17 g/L, an ethanol yield of 0.48 +/- 0.01 g/g, and an ethanol productivity of 0.12 +/- 0.01 g/(L/h), which represents increases of 106.02, 89.98, and 107.02\%, respectively, over the values obtained from SScF with untreated SCB.
A high-performance liquid chromatography (HPLC) method with photo-diode array (DAD) detection was developed to separate and quantify flavonoids in sugarcane leaves and bagasse (= the crushed sugarcane refuse from juice extraction), and in sugarcane juice. Sugarcane flavonoids consist of a complex mixture of aglycones and glycosides (including flavonolignan glycosides), and the HPLC-UV method herein proposed is suitable for their quantification as total flavonoids. This method was applied to analyze samples of cultivated sugarcane, commercial juice and transgenic sugarcane leaves. Sugarcane leaves proved a promising source of flavonoids: an average of 1.10 mg of total flavonoids/g plant material was found in fresh leaves. Moreover, the flavonoid content of sugarcane juice (0.6 mg/mL) is comparable to other food Sources of flavonoids previously reported. Transgenic sugarcane leaves ({''
Sugarcane molasses was chosen as an example material for the investigation of the influence of spray drying approach (conventional high temperature and a developed low temperature drying method which applies dehumidified air as a process gas) and the presence of drying carrier on volatile aroma compounds (VACs). Among 28 identified VACs 10 were chosen for detailed investigation. The influence of drying depended, apart from two mentioned factors, also on the type/origin of VACs and particle morphology. In the case of compounds connected with the fermentation process, the retention was higher after high temperature spray drying. On the contrary, VACs which could be additionally created during spray drying, thus Maillard reaction and caramelization reaction products, were more abundant in samples dried at lower temperature. As was explained, this contradictory phenomenon could be related to the higher evaporative loss at higher temperature, and also the fact that particles created at higher temperature were partially destroyed (as evident from the SEM photos). The presence of carrier increased the content of VACs after low temperature spray drying, which was connected to the encapsulation mechanisms of high molecular weight material. Thus, the most beneficial was the simultaneous application of carrier and low temperature spray drying approach.
Improvements on energy density of loose biomass such as sugarcane feedstock is crucial in the technology of biomass energy conversion and generation. South Africa is one of the producers and refiners of sugarcane. High energy density of sugarcane bagasse biomass through separation and briquetting is imperative in developing adequate streams and quality energy generation from sugarcane upstream milling processes. Unseparated bagasse and separated fractions of fiber and pith possess energy contents of about: 16.14 MJ/kg, 17.73 MJ/kg and 15.74 MJ/kg respectively. Fiber fractions have high energy content than bagasse and pith which demonstrates that pith fraction from bagasse lowers energy density. However, the use of starch and PVA (Polyvinyl Alcohol) as binders during briquetting contributed no significant difference in the overall energy density of the biomass briquettes produced. In the same vein, the addition of 50\% charcoal as the hybrid component significantly improves the energy density and the physical properties of briquettes, biomass fractions of bagasse, fiber and pith to: 19.43 MJ/kg, 19.57 MJ/kg and 18.37 MJ/kg respectively. Fiber fraction remains the biomass fraction with highest energy content as compared to other fractions. After briquetting and drying of briquettes to moisture content below 12\%, there was a significant improvement on the burning rate, briquetting, binder, hybridization which does improve the biomass briquettes characteristics. Separation of bagasse is crucial under certain conditions since there are no significance differences in the energy density of bagasse fractions. However, the use of PVA and charcoal does pose the necessity of bagasse separation from its fractions for briquetting.
This work describes the preparation of a new chelating material derived from wood sawdust, Manilkara sp., and not only the use of a new support, but also a chemically modified sugarcane bagasse synthesized in our previous work to remove Zn2+ from aqueous solutions and electroplating wastewater. The first part describes the chemical modification of wood sawdust and sugarcane bagasse using ethylenediaminetetraacetic dianhydride (EDTAD) as modifying agent in order to introduce carboxylic acid and amine functional groups into these materials. The obtained materials such as the modified sugarcane bagasse, EB, and modified wood sawdust, ES were then characterized by infrared spectroscopy (IR) and CHN. The second part evaluates the adsorption capacity of Zn2+ by EB and ES from aqueous single metal solutions and real electroplating wastewater, which concentration was determined through direct titration with EDTA and inductively coupled plasma (ICP-OES). Adsorption isotherms were developed using Langmuir model. Zn2+ adsorption capacities were found to be 80 mg/g for ES and 105 mg/g for EB whereas for the industrial wastewater these values were found to be 47 mg/g for ES and 45 mg/g for EB. Zn2+ adsorption in the wastewater was found to be lower than in Zn2+ spiked solution due to the competition between other cations and/or interference of other ions, mainly Ca2+ and Cl- that were present in the wastewater. (C) 2009 Elsevier B.V. All rights reserved.
Sugarcane bagasse, an agricultural waste, was successfully converted into novel magnetic carbon composites by low temperature hydrothermal carbonization at 230 degrees C for 24 h, followed by heat treatment at 400 degrees C for only 1 h in air. Effects of NaOH and iron loading on the chemical properties of the composites were studied. In addition, various techniques were employed to investigate the physicochemical properties of the composites. Adsorption kinetics and isotherms were investigated with tetracycline (TC) for the magnetic composites. The magnetic carbon composite exhibited 48.35 mg/g maximum adsorption capacity and was highly stable chemically and mechanically, with also good magnetic properties. The adsorption of TC by the magnetic adsorbent was mainly attributed to H-bonds and p-p interactions. The results indicate that waste sugarcane bagasse from the sugar industries can be efficiently transformed to a magnetic adsorbent for TC removal via a facile environmentally friendly method. (C) 2016 Elsevier Ltd. All rights reserved.
The recycling of agricultural by-products to produce organomineral fertilizers and using them as soil amendments to improve soil physical and chemical characteristics is a feasible disposal solution for the sugarcane industry. This study aimed to evaluate the agronomic performance of a bio-based phosphate (P) fertilizer produced from mineral phosphates (Gafsa rock phosphate and TSP) and filter cake (FC) in two distinct soils varying in their particle sizes, namely clayey (CLY) and sandy loam (SDY). Biological tests were carried out to determine the performance of the OF for sugarcane production against commercial P sources. The addition of filter cake (+ FC) was responsible for an increase in yield when compared to soils that did not receive it (- FC), yet similar sugarcane production for either soil was obtained. Phosphorus use efficiency (PUE) was similar to 10\% higher in CLY under TSP +FC compared to phosphate rock (RPR) -FC. On the basis of our P fractionation data, the addition of FC decreased P concentrations in the more labile P fractions. Phosphorus X-rays Absorption Near Edge Structure (XANES) analysis indicated that even though P was predominantly associated with Fe- and Al-(hydr)oxides, application of FC led to a change in P speciation, causing a shift from Fe-bound P in the soil that did not receive filter cake into Al-bound P, and to an increase in P associated to organic compounds in the soil receiving this amendment. Our findings showed that PUE and dry matter yield of sugarcane can be increased in weathered soils when organic and inorganic P sources are combined to supply this element.
Elastic and viscoelastic properties of sugarcane bagasse-filled poly(vinyl chloride) were determined by means of three-point bending flexural tests and dynamic mechanical and thermal analysis. The elastic modulus, storage modulus, loss modulus, and damping parameter of the composites at fibre contents of 10, 20, 30, and 40\% in mass were determined, as well as those of the unfilled matrix. There was a correlation between the elastic modulus and storage modulus of the composites. Moreover, the elastic and viscoelastic properties of the composites were highly influenced by fibre content.
In this study, secondary brewery wastewater (SBWW) supplemented with sugarcane molasses (SCM) was used for SBWW treatment with concomitant lipid and carotenoid production by the yeast Rhodosporidium toruloides NCYC 921. In order to improve the biomass production, ammonium sulfate, yeast extract and urea were tested as nitrogen sources. Urea was chosen as the best low-cost nitrogen source. A fed-batch cultivation was carried out with SBWW supplemented with 10 g L-1 of sugarcane molasses as carbon source, and 2 g L-1 of urea as nitrogen source. A maximum biomass concentration of 42.5 g L-1 was obtained at t = 126.5 h and the maximum biomass productivity was 0.55 g L-1 h(-1) at t = 48.25 h. The maximum lipid content was 29.9 \% w/w (DCW) at t = 94 h of cultivation and the maximum carotenoid content was 0.23 mg g(-1) M 120 h of cultivation. Relatively to the SBWW treatment, after the batch phase, 45.8 \% of total Kjeldahl nitrogen removal, 81.7 \% of COD removal and 100 \% of sugar consumption were observed. Flow cytometry analysis revealed that 27.27 \% of the cells had injured membrane after the inoculation. This proportion was reduced to 10.37 \% at the end of the cultivation, indicating that cells adapted to the growth conditions.
Batch adsorption studies were carried out using H2SO4 modified sugarcane bagasse (HMSB) for the removal of hazardous Crystal Violet (CV) dye from aqueous solutions. The effects of initial solution pH, adsorbent dose, and temperature on the adsorption process were investigated. The Langmuir isotherm model well described the equilibrium dye uptake while the pseudo-second-order kinetic model showed good agreement with the experimental kinetic data. Gibb's free energy change (Delta G(0)) was spontaneous for all interactions, and the adsorption process exhibited endothermic enthalpy values. Results suggest that HMSB is an effective adsorbent for the removal of CV from wastewater.
Electricity generation through sugarcane bagasse is a extraordinary worth in Pakistan as its exploration through the sugarcane crop can provide food, feed, fuel, fiber, fodder, and fertilizer for future generations. Normally about 0.450 MWh of electricity is generated from 1000 kg of bagasse through cogeneration technology. Electricity potential of bagasse is estimated about 1598 GWh to 2894 GWh in Pakistan. The national policy regarding the subject is weighed up from J-tariff in 1990 to present biomass cogeneration policy 2013. Surplus electricity generated through cogeneration technology can be consumed to meet the household-level demands and creation of employment in rural areas. A substantial amount will be available to the factories. It will also help in reduction of green-house effect created by oil based generation. (C) 2015 Elsevier Ltd. All rights reserved.
The effect of six different conditions of wet oxidation (WO) pretreatment on fractionation and enzymatic convertibility of sugarcane bagasse was investigated. WO resulted in an increase of cellulose content of bagasse as a result of the solubilisation of hemicelluloses and lignin. The highest cellulose content, nearly 70\%, was obtained in the pretreatment at 195 degrees C, 15 min and alkaline pH. Pretreatments at 195 degrees C and 15 min solubilised 93-94\% of hemicelluloses and 40-50\% of lignin, while pretreatment at 185 degrees C, 5 min and alkaline pH solubilised only 30\% of hemicelluloses and 20\% of lignin. The highest sugar yield in the liquid fraction, 16.1 g/100 g, was obtained at 185 degrees C, 5 min and acidic pH. The highest formation of carboxylic acids, phenols and furaldehydes occurred at 195 degrees C, 15 min and acidic pH. Alkaline pH reduced the formation of furaldehydes, which was irrelevant for most WO conditions. All pretreatment conditions improved the enzymatic convertibility of cellulose. The highest convertibility, 74.9\% was achieved in the hydrolysis of the material obtained by pretreatment at 195 degrees C, 15 min and alkaline pH. Some xylan convertibility was also observed. (c) 2006 Elsevier Inc. All rights reserved.
This research investigated the effect of hydraulic retention time (HRT) on two-stage anaerobic membrane bioreactor (2-SAnMBR) performance treating sugarcane vinasse. The experimental setup consisted of an upflow acidogenic reactor and a continuous stirred methanogenic reactor, fitted with submersed microfiltration hollowfiber membranes. The results indicated excellent performance and robustness of 2-SAnMBR. The reduction in HRT of 5.3-3.1 days did not cause loss of its performance. The 2-SAnMBR showed high capacity of removing organic matter (97\%), producing biogas (6.3 Nm(3) of CH4 per m(3) of treated vinasse) and did not completely remove important nutrients to fertigation. Reducing the HRT, the average mass of soluble microbial products (SMP) and extracellular polymeric substances (EPS) per mass of mixed liquor volatile suspended solids (MLVSS) increased. Consequently, the transmembrane pressure (TPM) rate and fouling resistance rise. Despite the fouling effect, physical and chemical cleaning processes were able to recover operational permeability.
Biochar obtained from the oxygen-deficient thermochemical processing of organic wastes is considered to be an effective reinforcing agent in biocomposite development. In the present research, biocomposite film was prepared using sugarcane bagasse pyrolyzed biochar and polyvinyl alcohol (PVA), and its electrical and mechanical properties were assessed. The biocomposite films were produced by varying content (5 wt.\%, 8 wt.\% and 12 wt.\%) of the biochar produced at 400 degrees C, 600 degrees C, 800 degrees C and 1000 degrees C and characterized using X-Ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy. The experimental findings revealed that biochar produced at a higher pyrolyzing temperature could significantly improve the electrical conductance of the biocomposite film. A maximum electrical conductance of 7.67 x 10(-2) S was observed for 12 wt.\% addition of biochar produced at 1000 degrees C. A trend of improvement in the electrical properties of the biocomposite films suggested a threshold wt.\% of the biochar needed to make a continuous conductive network across the biocomposite film. Rapid degradation of tensile strength was observed with an increasing level of biochar dosage. The lowest tensile strength 3.12 MPa was recorded for the film with 12 wt.\% of biochar produced at 800 degrees C. Pyrolyzing temperature showed a minor impact on the mechanical strength of the biocomposite. The prepared biocomposites could be used as an electrically conductive layer in electronic devices.
This study refers to an experimental analysis of the fluid-dynamics of particles of sugarcane bagasse in a fluidization column with an internal diameter of 190 mm, which determined the minimum fluidization velocity of the particles with different characteristic diameters (0 < dp < 9.5 mm), using air as fluidization means. The results have shown that the minimum fluidization velocity has a tendency to increase as the diameter of the particle increases. However, in a certain range of diameter (0.88 mm < dp < 9.5 mm), where the particles have a high aspect ratio (length/diameter), it has not been possible to fluidize them. High superficial air velocities have been used, mainly due to the strong trend to interlace and to develop high adhesion forces in this type of particles, as well as the high porosity that is displayed. Based on the experimental results, two new models have been developed in order to determine the minimum fluidization velocity and the complete fluidization velocity of the sugarcane bagasse with diameters that range from 0.075 to 0.445 mm. The comparisons have been made by using correlations from the literature for the determination of the minimum fluidization velocity, and the experimental results have shown that the new suggested correlations finely predict this parameter, with a maximum error range of 6\%, respecting the experimental values.
In this study, the magnetic ferric oxide-sulfonated porous carbon materials (Fe3O4-SPC) were fabricated using the magnetic ferric oxide (Fe3O4) nanoparticles via the sulfonation process with sugarcane bagasse as a main cel-lulose source. The characterization revealed that the spherical shape of Fe3O4 nanoparticles decorated on lamellar porous carbon sheet with uniform size less than 100 nm. Meanwhile, the catalytic assessment on the degradation of methylene blue via the Fenton reaction showed the ratio of Fe3O4:SPC = 1:2 obtaining the ef-ficiency of 95\% after 45 min. Moreover, the material had high reusability, retaining over 95\% after 5 consecutive cycles.
This study explored the impact of different persulfate pretreatments on the substrate characteristics and enzymatic sugar yield of sugarcane bagasse (SCB) and the related mechanisms. We analyzed the biomass composition, physicochemical properties of SCB, enzymatic saccharification efficiency, pure commercial cellulose and lignin degradation dynamics, and center dot OH and SO4 center dot- generation properties under different persulfate pretreatments. The results revealed that potassium peroxymonosulfate (2KHSO(5)center dot KHSO4 center dot K2SO4, PPMS) pretreatment had a significant effect on SCB. Under the optimal pretreatment conditions, SCB pretreated with PPMS showed a reducing sugar yield of 67.98\%, a sugar conversion rate of 90.29\%, and a lignin removal rate of 87.49\%, which were about 2-3 folds those under pretreatment with peroxydisulfate (PDS) including sodium persulfate (Na2S2O8, SPS) and ammonium persulfate ((NH4)(2)S2O8, APS). PPMS had higher selectivity for lignin degradation and stronger free radical generation ability than PDS, which may be the main contributor to its superior pretreatment performance.
The yeast Dekkera bruxellensis is considered to be very well adapted to industrial environments, in Brazil, USA, Canada and European Countries, when different substrates are used in alcoholic fermentations. Our previous study described its fermentative profile with a sugarcane juice substrate. In this study, we have extended its physiological evaluation to fermentation situations by using sugarcane molasses as a substrate to replicate industrial working conditions. The results have confirmed the previous reports of the low capacity of D. bruxellensis cells to assimilate sucrose, which seems to be the main factor that can cause a bottleneck in its use as fermentative yeast. Furthermore, the cells of D. bruxellensis showed a tendency to deviate most of sugar available for biomass and organic acids (lactic and acetic) compared with Saccharomyces cerevisiae, when calculated on the basis of their respective yields. As well as this, the acetate production from molasses medium by both yeasts was in marked contrast with the previous data on sugarcane juice. Glycerol and ethanol production by D. bruxellensis cells achieved levels of 33 and 53 \% of the S. cerevisiae, respectively. However, the ethanol yield was similar for both yeasts. It is worth noting that this yeast did not accumulate trehalose when the intracellular glycogen content was 30 \% lower than in S. cerevisiae. The lack of trehalose did not affect yeast viability under fermentation conditions. Thus, the adaptive success of D. bruxellensis under industrial fermentation conditions seems to be unrelated to the production of these reserve carbohydrates.
Bacillus polymyxa (NRRL-18475) produced a levan-type fructan (B, 2 --> 6 fructofuranoside) when groAn on sucrose, sugarcane juice, and sugarbeet molasses. The organism converted about 46\% of the fructose moiety of sucrose to levan when grown on sucrose medium, however, the yields of levan from sugarcane juice and beet molasses were much less than sucrose solution. Such sugarcane juice and beet molasses can be made a good substrate for levan production by various modifications. Adding peptone to sugarcane juice or passing beet molasses through a column of gel filtration media improved levan yield to a level almost comparable to that obtained from sucrose.
Laboratory-scale experiments in an enlarged scale thermoreactor have demonstrated that the pyrolysis of the bagasse bulk in a mechanically loosened layer yields 23-28\% charcoal measured on an oven dry basis. The charcoal is appropriate for the production of fuel briquettes and granules for household and industry uses. To implement an energy self-sufficient production process, yields of condensable matter and gas components were determined. It is shown that their combined heat of combustion exceeds the upper limit of the heat necessary to carbonise the biomass by 1.6 to 1.8 times. To overcome the difficulties caused by a high fine particles content and the fibrous structure of bagasse, the use of a rotary drum type apparatus is suggested to be appropriate. Due to technological considerations, a two-stage process may be recommended: a heating up and pyrolysis stage up to 350 degrees C, and a charcoal glowing stage with the peak temperature 475-500 degrees C. Such a reactor unit with a joint furnace and closed pyroligneous vapour and heat carrier flow system, greatly reduces the emission of carbon monoxide (CO) and dust particles. Bagasse can be used as an alternative source of traditional wood for charcoal production. It could prevent the deforestation of native forests. (C) 1999 Elsevier Science Ltd. All rights reserved.
The xylooligosaccharides (XOS, prebiotics) production from xylan extracted from sugarcane bagasse (SB) biomass was accomplished using an in-house produced xylosidase-free endoxylanase from an isolate Aspergillus flavus MG-7. Delignification of SB by sodium hypochlorite, and xylan extraction by coupled sodium hydroxide and thermal treatment were optimized for various process variables based on Design of Experiments (DoE) to achieve enhanced xylan yield (96.11\%, w/w). The extracted xylan was analysed by Fouriertransform infrared spectroscopy and thermogravimetric analysis to evaluate its structural morphology, purity and thermal stability. Xylan hydrolysate obtained by endoxylanase was quantified for xylobiose (69.57\%, w/w), xylotriose (13.17\%) and xylotetrose (8.377\%), and XOS were examined by H-1 NMR. Growth-promoting potential of XOS was established for a probiotic Lactobacillus plantarum M-13 isolated from kalarei. XOS exhibited excellent bioactivity potential in terms of high positive prebiotic activity score, significant antioxidant activity and antibacterial activity. Efficient XOS production promises value-addition for biorefining of SB biomass.
This study aimed to determine the hygroscopic equilibrium and isosteric heat of sugarcane bagasse to evaluate sorption dynamics and the required energy to vaporize water in the bagasse dehydration. The reaction was assessed at different controlled conditions of temperature (20, 40, 55 and 70 degrees C) and air relative humidity (10, 12, 17, 18, 30, 40, 45, 50, 60 and 85\%), as well as testing various models described in the literature to identify the condition that better represents sorption behavior. As a result, we found that the model that best fit empirical data of sugarcane bagasse sorption was the modified Henderson with determination coefficient of 0.972; while the integral isosteric heat of desorption ranged from 2,524.09 to 2,951.95 kJ kg(-1), for all water contents and equilibrium of 0.014 until 0.170 bs, respectively.
BACKGROUND The demand for green products is pushing industries to search for more eco-friendly materials, especially for food packaging applications. Starch biopolymer has been recognized as biodegradable material that can be produced from various plants. However, the strength of starch-based bioplastic retards their widespread application. Simultaneously, the high amount of agricultural waste produced by the food industry has been a growing environmental issue. Incorporating agro-waste fibers as a biofiller in starch-based bioplastic can improve the properties of the bioplastic, allowing its use in various applications. Thus, this study aims to evaluate the effect of chemical treatment on the structural, thermal, and mechanical properties of sugarcane bagasse as filler for starch-based bioplastic. RESULTS Results showed that alkaline treatment improved surface roughness and freed it of surface impurities. Results revealed that the thermal stability and mechanical properties improved significantly with the incorporation of sugarcane bagasse (SB) loading into potato starch (PS). The highest tensile strength (5.30 MPa) and Young's modulus (28.72 MPa) were exhibited by the sample with 6\% SB loading and further increments of SB led to a decrease in the strength of the biopolymer. CONCLUSION The incorporation of alkali-treated SB could increase and enhance the tensile strength and thermal stability of the bioplastic. This would contribute to reinforced materials that will allow for the application of PS as a new potential biodegradable material. Thus, it reduces the disposal period process and has great potential as an environmentally friendly, biodegradable, and renewable material. (c) 2022 Society of Chemical Industry (SCI).
Cellulose acetate is one of the components employed in drug controlled-release systems in the form of membranes. The aim of this study was to examine the controlled-release of doxycycline employing cellulose acetate symmetric and asymmetric membranes as matrices. The cellulose triacetate was produced from sugarcane bagasse through a homogeneous acetylation reaction, using acetic acid as the solvent, acetic anhydride as the acetylating agent and sulfuric acid as the catalyst. The viscosity average molecular weight of the cellulose acetate produced was 39,000 g mol(-1). The symmetric membranes were produced using a system solvent of dichloromethane/ethanol (9:1, v/v) and the asymmetric membranes were produced from the same solvent system and 10\% of water. For the formulation of both, 5\% of doxycycline was used. The membranes were characterized by thermal analysis (DSC and TGA) and scanning electron microscopy SEM. The release of doxycycline through cellulose triacetate matrices was examined using spectrophotometric analysis in the ultraviolet-visible region, at 275 nm. The results revealed that asymmetric membranes release 80\% of the drug in 100 min, while symmetric membranes release 14\% of the drug during the same time interval. (C) 2010 Elsevier B.V. All rights reserved.
Targeting the removal of Pb(2+)in wastewater, sugarcane bagasse was treated with nitric acid and an alkaline solution to prepare adsorbents. On a typical adsorbent, the adsorption isotherms agreed well with the Langmuir expression, and the maximum adsorption capacity reached 200.3 mg/g. In the presence of 150 ppm Ca2+, a common cation in natural water, the Pb(2+)adsorption capacity slightly declined. In contrast, Mg(2+)obviously prohibited the adsorption for Pb2+. The spent adsorbent could be regenerated at least five times through elution with an EDTA solution. EDS and XPS results demonstrated that nitric acid functioned as an oxidant instead of nitrification agent in the treatment of bagasse. The adsorption process was consistent with quasi-second-order kinetics. Based on thermodynamic studies, the changes in enthalpy and Gibbs free energy were calculated to be - 33.3 andca. - 18 kJ/mol, indicating that the adsorption process was exothermic and spontaneous. The equilibrium Pb(2+)adsorption amounts were proportional to the numbers of carboxylate groups on different adsorbents. The binding energies of Pd 4f(5/2)and Pd 4f(7/2)XPS spectra of Pb(2+)adsorbed were 0.6-0.7 eV lower than those of free Pb(NO3)(2), indicating the transfer of electrons during adsorption. The conversion of hydroxymethyl groups in sugarcane bagasse into carboxylate groups, as well as the chelation between Pb(2+)ions and carboxylate groups, was validated in this work, which is beneficial for the treatment of wastewater polluted by lead ions.
This study aimed to select a yeast strain that effectively utilises xylose to produce xylitol from the vinasse of ethanol broth obtained from the fermentation of sugarcane bagasse hydrolysate. Eleven strains of xylose-fermenting yeasts were evaluated for their abilities to utilise xylose and produce xylitol. Two strains that showed outstanding performance in the semi-defined xylose medium were selected for further testing with a vinasse medium. Candida guilliermondii TISTR 5068 showed a superior xylitol production of 7.03 +/- 0.08 g/L with the xylitol yield of 0.70 g/ gxylose when cultured in bagasse-based ethanol vinasse. The strain was further tested for its xylitol production performance when cultured at four different agitation intensities. Excessive agitation resulted in a rapid xylitol production rate but caused xylitol consumption once the xylose was depleted. Moderate agitation resulted in the highest xylitol yield of 0.79 g/gxylose. The results of this study have provided important information for the development of the xylitol production process using waste streams from cellulosic ethanol production.
The objective of this work was to evaluate the effect of different amounts of straw on the root system and productivity of sugarcane (Saccharum officinarum), of first and second ratoons, in an Oxisol. Six treatments were evaluated: 0, 5 (25\%), 10 (50\%), 15 (75\%), and 20 Mg ha(-1) (100\%) straw and burned sugarcane of the first and second ratoons. `SP80-1816' sugarcane was used. Root mass at 0.45 and 0.75 m away from the row, and up to 0.60 m deep was evaluated. In the first ratoon, treatments with 50, 75 and 100\% straw provided greater root mass up to 0.20-m depth, in comparison to treatments of burned sugarcane, and 0 and 5 Mg ha(-1) (25\%) straw. The treatments with 50 and 75\% straw had 43\% higher yields than burned sugarcane (110 Mg ha(-1)). The treatment with 10 Mg ha(-1) straw (50\%) was sufficient to provide increased root mass and productivity of sugarcane. The root system and the productivity of sugarcane are favored by the change of burned-sugarcane harvesting system to sugarcane under straw.
PurposeThe aim of this research was to determine the vinasse irrigation effects on the arbuscular mycorrhizal fungi (AMF) population (total spore abundance (TSA), richness, relative abundance, and diversity indices) and soil parameters and nutrients at high doses. The irrigation of soil with vinasses derived from sugarcane, beet, or alcohol production is a common practice around the world. Little is known about how this affects the AMF community and soil nutrients.Materials and methodsThe spider plant (Chlorophytum comosum, (Thunb.) Jacques), a mycorrhizable plant, was used to investigate the effect of 4months of frequent vinasse irrigation (0, 25, 50, 75, and 100\% vinasse concentration) on AMF and soil characteristics, e.g., electrical conductivity (EC), pH, mineral N, available P, Na+, K+, Ca2+, and Mg2+.Results and discussionThe vinasse irrigation decreased the TSA, AMF richness and diversity after 4months, regardless of vinasse concentration. The vinasse irrigation did not acidify the soil, but the EC, mineral N and available P increased. The biomass of C. comosum decreased (77-81\%) after vinasse irrigation for 4months.ConclusionsFrequent irrigation with vinasse at concentrations 50\% increases EC, K+, Na+, Mg2+, Ca2+ and available P in the soil, and decreases the amount of AMF spores, richness and diversity, which is not desirable in agricultural soils.
Three abundant coffee residues (green coffee powder, parchment and defatted cake) and sugarcane vinasse were co-digested under thermophilic anaerobic conditions. A pilot plant was set-up and operated under optimized conditions using mesophilic sludge seed to produce biohydrogen. The initial conditions were acidogenic regimes (pH 5.0-6.5) followed by methanogenic conditions (pH 6.5-8.0). Results indicated the concomitant generation of biohydrogen and biomethane (termed biohythane) from the coffee residues. The green coffee powder bioreactor produced a hydrogen-rich biohythane for the first 15 days with a maximum yield on day four (31.45\% hydrogen). Results also suggested that start-up of the biosystem reached the methanogenic stage in only 20-25 days and produced methane yields as high as 0.14mlCH(4)/gVS(added). For the co-digestion of defatted cake and vinasse, the only gas of interest produced was biohydrogen 32\% vol./vol. between the 9th and 32nd day. Anaerobic co-digestion of parchment and vinasse produced biohythane at an average yield of 0.21mlCH(4)/gVS(added).
Background: Polymalic acid (PMA) is a water-soluble biopolymer with many attractive properties for food and pharmaceutical applications mainly produced by the yeast-like fungus Aureobasidium pullulans. Acid hydrolysis of PMA, resulting in release of the monomer lLio-based platform chemicals. Results: In this study, the production of PMA and MA from sucrose and sugarcane molasses by A. pullulans was studied in shake flasks and bioreactors. Comparative metabolome analysis of sucrose- and glucose-based fermentation identified 81 intracellular metabolites and demonstrated that pyruvate from the glycolysis pathway may be a key metabolite affecting PMA synthesis. In silico simulation of a genome-scale metabolic model (iZX637) further verified that pyruvate carboxylase (pyc) via the reductive tricarboxylic acid cycle strengthened carbon flux for PMA synthesis. Therefore, an engineered strain, FJ-PYC, was constructed by overexpressing the pyc gene, which increased the PMA titer by 15.1\% compared with that from the wild-type strain in a 5-L stirred-tank fermentor. Sugarcane molasses can be used as an economical substrate without any pretreatment or nutrient supplementation. Using fed-batch fermentation of FJ-PYC, we obtained the highest PMA titers (81.5, 94.2 g/L of MA after hydrolysis) in 140 h with a corresponding MA yield of 0.62 g/g and productivity of 0.67 g/L h. Conclusions: We showed that integrated metabolome- and genome-scale model analyses were an effective approach for engineering the metabolic node for PMA synthesis, and also developed an economical and green process for PMA and MA production from renewable biomass feedstocks.
This work evaluated ethanol production from sugarcane bagasse at high solids loadings in the pretreatment (20-40\% w/v) and hydrolysis (10-20\% w/v) stages. The best conditions for diluted sulfuric acid, AHP and Ox-B pretreatments were determined and mass balances including pretreatment, hydrolysis and fermentation were calculated. From a technical point of view, the best pretreatment was AHP, which enabled the production of glucose concentrations near 8\% with high productivity (3.27 g/L h), as well as ethanol production from 100.9 to 135.4 kg ethanol/ton raw bagasse. However, reagent consumption for acid pretreatment was much lower. Furthermore, for processes that use pentoses and hexoses separately, this pretreatment produces the most desirable pentoses liquor, with higher xylose concentration in the monomeric form. (C) 2015 Elsevier Ltd. All rights reserved.
This work analyzed different processes of ethanol fermentation from pretreated sugarcane straw. The conversion process, addressing enzymatic hydrolysis and fermentation of C5 and C6-sugars, and the determination of two economic indicators of the best configuration, were covered in this study. Design of experiments combined with Desirability function were applied to select the best combination of glucose concentration and yield in the enzymatic hydrolysis step, resulting in a glucose yield similar to 30g/100 g of initial raw material under conditions of 13\% of solid load and 30 FPU/g pretreated SCS. In addition, some fermentation configurations were evaluated. A presaccharification previous to simultaneous saccharification and fermentation (PSF) had a higher result in ethanol concentration and yield. The application of this configuration and fermentation of C5 sugar from the pretreatment step yields 215.05 L/ton SCS. Return of investment and payback period, as economic indicators, suggest that the alternative PSF is suitable for adoption by sugarcane industry under the evaluated conditions. (C) 2020 Elsevier Ltd. All rights reserved.
Pervious concrete (PC) is a new type of concrete that is gaining popularity because of its low-impact development capabilities and ability to reduce stormwater runoff. The current study focuses on the potential use of waste from the sugarcane industry and on flexible pavement, specifically sugarcane bagasse ash (SBGA) and reclaimed asphalt pavement (RAP), to create PC mixes. Furthermore, an unconventional method was used to extract the benefits of RAP without compromising the structural integrity of PC: designing the mixture based on hydrological properties rather than mechanical parameters and then improving structural integrity through the use of SBGA without compromising the hydrological capacity of the designed PC mixture. Six PC mix combinations were developed by substituting recycled asphalt pavement for natural coarse aggregate in varying proportions of 0, 50, and 100 \%. Following that, three RAP-incorporated PC mixes were created using 5, 10, and 15 \% SBGA as a partial replacement for cement. It was discovered that using SBGA as a partial replacement for cement reduces mechanical properties while increasing functional properties such as permeability. Surprisingly, no significant differences were observed in the percentage voids of PC mixes containing RAP aggregates. The addition of 10 \% SBGA significantly improves the mechanical properties of 100 \% coarse RAP (cRAP)-inclusive PC mixes. When the total cost of 1 m(3) concrete was calculated, the addition of cRAP aggregates and SBGA in pervious concrete pavements mixes resulted in a 44 \% reduction. Furthermore, the current study suggests replacing 10 \% of ordinary Portland cement with SBGA in cRAP inclusive PC mixes, as this increases the strength of cRAP-PC mixes while also providing environmental and economic benefits.
The process of mechanical harvesting of sugarcane generates a large deposition of straw on the soil surface, providing a coverage that several studies have found important for reducing the weed population. Although such coverage reduces weed infestations, additional management, including chemical control, is still needed. Thus, this study aimed to evaluate the leaching of atrazine, pendimethalin, metribuzin, clomazone, diuron and hexazinone in sugarcane straw. The experiment was conducted at the School of Agronomic Engineering at UNESP (Universidade Estadual Paulista) - Botucatu/SP. The sugarcane straw was collected in the field, cut and placed in quantities of 10t ha(-1) in the capsules used as experimental units. The experimental design was completely randomized, using six herbicide treatments and four replications. Within 24 hours after the herbicides were applied in capsules with straw, five different rainfalls (5, 10, 20, 50 and 100mm) were simulated. The leached water was collected for chromatographic analysis. The herbicide percentages that crossed the straw layer were statistically correlated with the rainfall amount by the Mitscherlich model that compares the facility of herbicide removal from sugarcane straw. In summary, pendimethalin did not present quantified transposition of the product by sugarcane straw even with a rain simulation of 100 mm. Furthermore, two different profiles of facility to transpose the herbicides in straw were found: one for metribuzin and hexazinone that crossed quickly through the straw layer and another for atrazine, diuron and clomazone that required more rainfall to be leached from coverage to the soil according to the maximum removable amount of each herbicide.
Natural fibers such as Banana fiber and sugarcane bagasse powder are used in the present study, which are abundantly available at low cost. Novel hybrid natural fiber reinforced composite specimen prepared by using the matrix material as epoxy (70\%) with the addition of hardener and the reinforcement material (30\%) used as NaOH chemical treated banana fiber with the addition of filler material as sugarcane bagasse powder to enhance the property. To prepare the composite material hand-lay process is used and manufactured three different combination of specimen by varying the composition ration of 10\%, 15\%, and 20\% of reinforced material. The mechanical properties such as tensile, compression, flexural, Impact test of the prepared specimen have been evaluated as per the ASTM standards. The mechanical properties results depicts that the specimen prepared with chemically treated fiber gives more strength as compared to untreated fiber composites. The morphological study evidences the proper fiber used while preparing the hybrid composite material. The maximum tensile strength achieved in specimen is 73.48 MPa, compressive strength of 99.63 MPa, flexural strength of 77.50 MPa, Impact strength of 4.8 J/mm, Vickers hardness value of 59.6. The specimen prepared with chemically treated specimen has a higher percentage of water absorption than the untreated. This novel hybrid composite material can be used in automobile, aircraft, building, sports, and household applications.
We report the purification and characterization of two thermophilic xylanases from the mesophilic bacteria Cellulomonas flavigena grown on sugarcane bagasse (SCB) as the only carbon source. Extracellular xylanase activity produced by C. flavigena was found both free in the culture supernatant and associated with residual SCB. To identify some of the molecules responsible for the xylanase activity in the substrate-bound fraction, residual SCB was treated with 3 M guanidine hydrochloride and then with 6 M urea. Further analysis of the eluted material led to the identification of two xylanases Xyl36 (36 kDa) and Xyl53 (53 kDa). The pI for Xyl36 was 5.0, while the pI for Xyl53 was 4.5. Xyl36 had a K (m) value of 1.95 mg/ml, while Xyl53 had a K (m) value of 0.78 mg/ml. In addition to SCB, Xyl36 and Xyl53 were also able to bind to insoluble oat spelt xylan and Avicel, as shown by substrate-binding assays. Xyl36 and Xyl53 showed optimal activity at pH 6.5, and at optimal temperature 65 and 55 degrees C, respectively. Xyl36 and Xyl53 retained 24 and 35\%, respectively, of their original activity after 8 h of incubation at their optimal temperature. As far as we know, this is the first study on the thermostability properties of purified xylanases from microorganisms belonging to the genus Cellulomonas.
Inspired by the presence of anthropogenic organic matter in highly fertile Amazonian Dark Earth (ADE), which is attributed to the transformation of organic matter over thousands of years, we explored hydrothermal carbonization as an alternative for humic-like substances (HLS) production. Hydrothermal carbonization of sugarcane industry byproducts (bagasse and vinasse) in the presence and absence of H3PO4 afforded HLS, which were isolated and compared with humic substances (HS) isolated from ADE in terms of molecular composition and maize seed germination activity. HLS isolated from sugarcane bagasse hydrochar produced in the presence or absence of H3PO4 comprised both hydrophobic and hydrophilic moieties, differing from other HLS mainly in terms of phenolic content, while HLS isolated from vinasse hydrochar featured hydrophobic structures mainly comprising aliphatic moieties. Compared to that of HLS, the structure of soil-derived HS reflected an increased contribution of fresh organic matter input and, hence, featured a higher content of O-alkyl moieties. HLS derived from lignocellulosic biomass were rich in phenolics and promoted maize seed germination more effectively than HLS comprising alkyl moieties. Thus, HLS isolated from bagasse hydrochar had the highest bioactivity, as the presence of amphiphilic moieties therein seemed to facilitate the release of bioactive molecules from supramolecular structures and stimulate seed germination. Based on the above results, the hydrothermal carbonization of lignocellulosic biomass was concluded to be a viable method of producing amphiphilic HLS for use as plant growth promoters. (C) 2019 Elsevier B.V. All rights reserved.
In this work, we report on the biosorbent bio-composite consisting of pretreated sugarcane bagasse, chitosan, and epichlorohydrin, which was prepared using the blending method for the adsorption of phosphate from aqueous media. The effect of solvent concentration was investigated, and it was observed that the high solvent concentration significantly enhanced the extraction of cellulose. Moreover, pretreatment enhances the compatibility between the extracted cellulose and chitosan. Furthermore, the addition of epichlorohydrin significantly enhanced the adsorption capacity as well as the stability of the synthesized biosorbent bio-composite. Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron microscope, X-ray diffraction, and thermogravimetric analysis were used to characterize the prepared bio-composite. Batch studies were conducted to investigate the effectiveness of the bio-composite. The mechanism of adsorption between the biosorbent biocomposite and phosphate was through chemisorption as the data best fitted to the pseudo-second-order kinetic model. The isotherm study showed that the data best fitted to the Freundlich adsorption isotherm model, and the Langmuir adsorption isotherm model showed that the maximum adsorption capacity was 15.26 mg/g. The biosorbent was found to be pH dependent, selective, and recyclable.
Sugarcane is among the principal agricultural crops cultivated in tropical countries. The annual world production of sugarcane is similar to 1.6 billion tons, and it generates similar to 279 million metric tons (MMT) of biomass residues (bagasse and leaves). Sugarcane residues, particularly sugarcane bagasse (SB) and leaves (SL) have been explored for both biotechnological and non-biotechnological applications. For the last three decades, SB and SL have been explored for use in lignocellulosic bioconversion, which offers opportunities for the economic utilization of residual substrates in the production of bioethanol and value-added commercial products such as xylitol, specialty enzymes, organic acids, single-cell protein, etc. However, there are still major technological and economic challenges to be addressed in the development of bio-based commercial processes utilizing SB and SL as raw substrates. This article aims to explore SB and SL as cheaper sources of carbohydrates in the developing world for their industrial implications, their use in commercial products including commercial evaluation, and their potential to advance sustainable bio-based fuel systems. Copyright (c) 2011 Society of Chemical Industry
Converting biomass to fermentable sugar is the critical step in the biomass refinery. Moreover, pretreatment of biomass plays an important role in improving the conversion of biomass to sugar. In this study, sugarcane bagasse was pretreated by metal chloride Lewis acids (0.1 mol L-3 CrCl3, FeCl3, FeCl2, ZnCl2 and AlCl3 solution) for cellulase hydrolysis. The effects of pretreatments on the yield, chemical components, and sequential cellulase hydrolysis of pretreated bagasse were investigated. The results indicated that metal chlorides with different pKa values could efficiently remove the hemicellulose in bagasse during pretreatment. Furthermore, an inhibition factor (IF) quantitatively reflecting difficulty of cellulase hydrolysis was proposed. The low IF means the facile cellulase hydrolysis. The IF of Fe (III)-pretreated bagasse could decrease to 1.35. In this case, the enzymatic digestibility of bagasse approached to 100\%. (C) 2014 Elsevier Ltd. All rights reserved.
Pretreatment of lignocellulosic biomass is of the utmost importance for the development of bioethanol because of the abundance and low cost of lignocelluloses. To figure out the hydrolysis characteristics of sugarcane bagasse in a microwave irradiation environment, the biomass is pro:mated by a dilute sulfuric acid solution at 180 degrees C for 30 min, with the concentration ranging from 0 to 0.02 M. A variety of analyses, including fiber analysis, TGA, XRD, FTIR and HPLC, are employed to aid in understanding the physical and chemical characteristics of residual solid particles and solutions. A higher concentration is conducive to destroying bagasse; however, the buffering capacity possessed by the biomass is also observed in the pretreatment. The experimental results indicate that around 40-44 wt\% of bagasse is degraded from the pretreatment in which around 80-98\% of hemicellulose is hydrolyzed. In contrast, crystalline cellulose and lignin are hardly affected by the pretreatment. The maximum yields of xylose and glucose as well as the minimum furfural selectivity occur at the acid concentration of 0.005 M. Consequently, the aforementioned concentration is recommended for bagasse pretreatment and bioethanol production. (c) 2011 Elsevier Ltd. All rights reserved.
Sugarcane bagasse ash (SCBA) has been pitched as a feasible supplement that can ease the sustainability issues associated with cementitious materials. In this respect, SCBA has been well researched with over 100 journal publications. However, there is a scarcity of comprehensive reviews detailing the research developments so far. Therefore, this study is a holistic review with a large scope, content and coverage that emanated from a comprehensive dissection of the literature. The study systematically reviewed the SCBA's origin of pozzolanicity, processing approaches, sustainability potentials, and performance in cementitious materials. The performance entailed characterisation, pozzolanic activity, microstructure refinement, fresh and rheological properties, mechanical and durability properties. SCBA processing is key to its reactivity and performance; hence, recommendations were made on the best processing approach. Performance ranging from 80 to 160\% of the control (without SCBA) exist in the literature. Such performance emanates from a conservative use of about 20-25\% or further processing that yields optimum contents up to 50\%. This study serves as an up-to-date appraisal of data and researches related to the use of SCBA in cementitious materials.
Homogeneous modification of sugarcane bagasse with succinic anhydride (SA) was investigated in novel solvent systems ionic liquid 1-butyl-3-methylimidazolium chloride/dimethyl sulfoxide ({[
The objective this experiment was to evaluate chemical-bromatologic composition and in vitro dry matter digestibility of sugarcane bagasse submitted to ammonization with urea. The treatments were four urea dose added to the sugarcane bagasse and addition of 1.2\% (DM basis) of soybean as urease source. The experimental design utilized was a completely randomized. The bagasse was stored in PVC silos with 5.3 L capacity, which were opened after 110 days of ammonization. With the urea dose addition to the bagasse, crude protein levels increased linearly. The neutral detergent fiber, acid detergent fiber, hemicelluloses, cellulose, lignin and total carbohydrates levels decreased, while the acid detergent insoluble nitrogen, neutral detergent insoluble nitrogen, nonfibrous carbohydrates, ammonia nitrogen levels and pH increased significantly with urea addition. At evaluated dose, the urea added to bagasse provides increase in nitrogen compounds content, decrease of fiber compounds, and increases the in vitro dry matter digestibility. Estimated by regression equation. the addition of 2.62\% urea to sugarcane bagasse provides the minimum crude protein level to good functioning of the rumen.
Anaerobic co-digestion (AcoD) of the main residues from the non-centrifugal cane sugar (NCS) making process, agricultural crop residues (ACR) and sugarcane scum (SCS), was evaluated using biochemical methane potential tests. Substrates were pretreated: ACR through particle size reduction, and SCS with dilution. The maximum methane yield of 0.276 Nm(3) CH4 kg(-1) VSadded occurred at an ACR of 2 mm and at 12.5\% dilution of SCS, at a ratio of 75:25 based on volatile solids, which was 30.2\% and 5.9\% higher compared to SCS and ACR in mono-digestion, respectively. ACR was a substrate of adequate buffer capacity for the AcoD stability, while the SCS, in addition to helping accelerate the process, also helped improve the inoculum's methanogenic and hydrolytic activity. The first-order kinetic and dual-pool two-step models were suitable to describe methane yield. AcoD of ACR with SCS is a good option for the treatment of streams in the NCS agribusiness sector.
A cellulose grafted copolymer was synthesized by homogeneous grafting 2-(Dimethylamino)ethylmethacrylate (DMAEMA) onto the sugarcane bagasse cellulose under microwave irradiation. Cellulose was dissolved in 1-butyl-3-methylinidazolium chloride ionic liquid ({[
The aim of this work was to have cellulase activity and hemicellulase activity screenings of endophyte Acremonium species (Acremonium zeae EA0802 and Acremonium sp. EA0810). Both fungi were cultivated in submerged culture (SC) containing l-arabinose, d-xylose, oat spelt xylan, sugarcane bagasse, or corn straw as carbon source. In solid-state fermentation, it was tested as carbon source sugarcane bagasse or corn straw. The highest FPase, endoglucanase, and xylanase activities were produced by Acremonium sp. EA0810 cultivated in SC containing sugarcane bagasse as a carbon source. The highest beta-glucosidase activity was produced by Acremonium sp. EA0810 cultivated in SC using d-xylose as carbon source. A. zeae EA0802 has highest alpha-arabinofuranosidase and alpha-galactosidase activities in SC using xylan as a carbon source. FPase, endoglucanase, beta-glucosidase, and xylanase from Acremonium sp. EA0810 has optimum pH and temperatures of 6.0, 55 A degrees C; 5.0, 70 A degrees C; 4.5, 60 A degrees C; and 6.5, 50 A degrees C, respectively. alpha-Arabinofuranosidase and alpha-galactosidase from A. zeae EA0802 has optimum pH and temperatures of 5.0, 60 A degrees C and 4.5, 45 A degrees C, respectively. It was analyzed the application of Acremonium sp. EA0810 to hydrolyze sugarcane bagasse, and it was achieved 63\% of conversion into reducing sugar and 42\% of conversion into glucose.
The corrosion of reinforced ternary concretes containing fly ash (FA) and untreated sugarcane bagasse ash (UtSCBA) was evaluated. Chloride-ion diffusion at 28 and 90 days, as well as microstructural properties, percentage of voids, and compressive strength (CS) in cylinders were evaluated at 2500 days of age. Moreover, corrosion was monitored in prismatic specimens exposed to a NaCl solution by corrosion potentials and linear polarization resistance techniques. Results show that the combination of FA plus UtSCBA decreased the chloride-ion diffusion and did not affect the compressive strength (CS) of the concrete. For the studied concretes, the combination of FA plus UtSCBA appears a suitable option against chloride-induced corrosion. (C) 2018 Elsevier Ltd. All rights reserved.
Bagasse from sugarcane, a waste material, has been studied as a biosorbent for removing lead from aqueous solutions in batch systems. In this study. bagasse was modified by sulphuric acid to enhance sorption capacity for lead and the origin of the enhancement was investigated by observing the change in surface functional group concentrations and the lead sorption behaviours. The untreated and treated bagasse was characterized by elemental analysis, SEM, FTIR and potentiometric titrations. Titrations revealed two different types of sites present on both solid wastes that probably correspond to carboxyl and amine groups. Sorption isotherm test showed that equilibrium sorption data were better represented by Langmuir model than the Freundlich model. The sorption capacities for lead of untreated bagasse and bagasse treated by H2SO4 were 6.366 and 7.297 mg/g, respectively at 25 degrees C and pH 5. (C) 2010 Elsevier B.V. All rights reserved.
Sugarcane (Saccharum officinarum L.) molasses, rich in phenolic compounds, is an undervalued coproduct during sugar production. However, limited attention was paid to the inhibitory effect of sugarcane molasses extract (SME) on hazardous compound formation during meat processing. In this study, SME with high antioxidant activity was extracted and purified by many steps. Chicken wings were deep-fried for 2.5 min and 5 min after being painted maltose-water solution (1:1, v:v) with different SME concentration (0.2, 0.5, 1.0, 1.5 and 2.0 mg/L). The heterocyclic amines (HCAs) levels in deep-fried chicken wings were measured. Total HCAs levels in deep-fried 2.5 min samples were 4.51-8.04 ng/g, with the inhibition rates ranged 32.5-43.9\% comparing with control. Likewise, total HCAs contents in samples after 5 min deep-frying were 26.2-37.4 ng/g, and the inhibition rates were 18.5-29.9\%. In addition, the inhibitory effect of SME on HCAs formation followed significant dose-effect relationships, by correlation analysis between SME antioxidant activities and HCAs contents. But the weak correlations between SME antioxidant activities and relative total free radical contents demonstrated that the inhibition mechanism of SME was more complex than scavenge free radicals. It may be attributed to SME inhibit the HCAs synthesis via both free radical pathway and Maillard reaction pathway.
Based on a five level central composite design (CCD) involving the variables substrate concentration (C), pH (P), incubation temperature (T) and fermentation time (H), a response surface methodology (RSM) for the production of ethanol from pretreated sugarcane bagasse by cellulase and yeast Kluyveromyces fragilis was standardized. The design contains a total of 31 experimental trials in which the first 24 organized in a factorial design and from 25 to 31 involving the replications of the central points. Data obtained from RSM on ethanol production were subjected to the analysis of variance (ANOVA) and analyzed using a second order polynomial equation. Maximum ethanol concentration (32.6 g/l) was obtained from 180 g/l pretreated sugarcane bagasse at the optimized process conditions (temperature 35 degrees C, pH 5.5) in 72 h aerobic batch fermentation. Various kinetic models such as logistic model, logistic incorporated leudeking piret model and logistic incorporated modified leudeking piret model have been evaluated and the constants were predicted.
This paper investigates the effects of sugarcane bagasse fibers (SCBFs) on the mechanical strength and durability properties of compressed and stabilized earth blocks (CSEBs). CSEBs were fabricated using natural soil and SCBFs, collected from Lakeland, LA, with a manually operated compression machine. Nine different soil mix compositions containing different amounts of SCBFs (0\%, 0.5\%, and 1.0\% by weight) and Type II Portland cement (0\%, 6\%, and 12\% by weight) were considered. The flexural, dry compressive, and wet compressive strengths of the different CSEBs were evaluated experimentally. Durability was also examined by measuring mass loss, dry density, water absorption, and wet compressive strength after 12 wetting/drying cycles. The morphology and chemical composition of the CSEBs were investigated via scanning electron microscopy and energy-dispersive X-ray spectroscopy, whereas the mineralogical characteristics were evaluated using X-ray crystallography. The results show that including 0.5\% to 1.0\% by weight of SCBFs in CSEBs stabilized with 12\% by weight of cement can significantly improve the CSEB mechanical properties without compromising their durability properties.
A lignin-coated fabric made from sugarcane bagasse exhibits antimicrobial characteristics. The bacterial strain Staphylococcus epidermidis (DMST 15505), a cause of skin infection commonly found in medical facilities, was used in this study. At specific coating concentration, in vitro study suggested this bacterium can be inhibited to prevent further propagation within 6h of contact with lignin-coated fabric. The price for lignin extraction at the laboratory scale (500ml) was approximately USD 974.60/kg and USD 15.22/kg at the pre-pilot scale (50l). The minimum inhibitory concentration (MIC) for lignin extracts was 4096 mu g/ml. A price-performance index (PPI) was proposed and calculated from the material price and the amount required to inhibit bacterial propagation based on the MIC according to the antimicrobial performance of the coated fabric. This index provides swift cost estimation of a product's antimicrobial properties to inhibit specific bacterial propagation. A smaller value of PPI is preferred when comparing multiple antimicrobial agents. The PPI for lignin was USD 0.0080 at the laboratory scale and USD 0.0002 at the pre-pilot scale. The PPI for commercial silver nanoparticles was USD 0.6084 (20nm) and USD 0.3498 (200nm). The PPI index supported the utilization of lignin extracts from sugarcane bagasse as a bio-based antimicrobial agent on fabric for antimicrobial textile application.
Sugarcane bagasse is an abundant biomass waste and a promising carbon source for preparing carbon-based materials such as carbon quantum dots (CQDs). Low quantum yield is a major problem for sugarcane bagasse-based carbon quantum dots. Heteroatom-doped modification is an efficient approach to improve the quantum yield. A facile hydrothermal carbonization method was applied to synthesize the nitrogen-doped carbon quantum dot N-CQDs using urea as the nitrogen source. The synthetic procedure was determined by the single-factor experiments and the response surface methodology (RSM) based on Box-Behnken design (BBD). The optical properties of optimized N-CQD-13 were more excellent than those of undoped CQD. Higher quantum yields (both absolute and relative) were observed in N-CQD-13. Additionally, N-CQD-13 exhibited high stability for long-time storage and excellent pH tolerance in aqueous solutions. N-CQD-13 were applied to detect Fe3+ in aqueous solutions with a low detection limit of 0.44 mu M. The fluorescence lifetime decay of the N-CQD-13 solutions untreated and treated with Fe3+ indicated the probable involvement of a dynamic fluorescence-quenching mechanism. Thus, this work explored a reliable method for the high-quality utilization of bagasse.
The design of biocomposite membranes based on microcrystalline cellulose (MCC) extracted from sugarcane bagasse added into matrices of poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) was fabricated by the phase inversion method. The pore formation of biocomposite membranes was prepared by the phase inversion method, and the obtained biocomposite membranes showed a tunable microstructure formed in the membranes that was investigated by field-emission scanning electron microscope. Due to the high porosity and hydrophilic properties of MCC, the biocomposite membranes demonstrated excellent electrolyte wettability, large electrolyte uptake (up to 138\%), and smaller interfacial resistance leading to enhancement of the ionic conductivity. Furthermore, the effects of MCC on the thermal properties of biocomposite membranes were evaluated by differential scanning calorimetry and the thermal shrinkage test. The addition of 5 wt\% MCC showed the outstanding thermal stability of the biocomposite membranes. After thermal treatment at 135 degrees C for 1 h, this biocomposite membrane exhibited shrinkage of only 32\% from the original shape while the PLA/PBS membrane showed shrinkage of 81\%, which verifies that the introduction of MCC improves the thermal stabilities of biocomposite membranes. Promisingly, the biocomposite membranes represent candidate alternatives for future battery applications. {[
5-Hydroxymethylfurfural (HMF) as value-added platform chemical can be derived from biomass. This study used microwave hydrothermal liquefaction (MHTL) to obtain HMF from sugarcane bagasse in acidic seawater conditions. The key processing parameters including temperature, reaction time, and liquid-to-solid ratio (L/S) were evaluated and optimized. The highest HMF yield of 8.1 wt\% was obtained at 149 degrees C with a reaction time of 4 min and a L/S value of 12:1, respectively. This yield is considerable and even higher than the yield derived from sugarcane molasses under similar microwave conditions in the absence of seawater. Hence, acidic seawater was found to promote the hydrolysis of sugarcane bagasse to give HMF precursor (i.e. fructose and glucose), while simultaneously inhibiting the conversion of HMF to levulinic acid under MHTL conditions, possibly explaining the high HMF yield. This method presents a new and sustainable means of transforming waste biomass to valuable substances using seawater or brine wastewater.
Mamaghan, local diatomaceous earth (DE) from Iran, was evaluated for controlling two storage beetles, Tribolium confusum Du Val. and Rhyzopertha dominica (F.). The effect of DE was enhanced by adding 15 and 20\% nanosilica synthesized from bagasse ash sugarcane byproduct. Sugarcane bagasse is potentially used as natural silica resources, and nanosilica was synthesized by the sol-gel technique. Nanosilica, untreated Mamaghan DE, and Mamaghan DE treated with 15\% and 20\% nanosilica were used in the experiments. The formulations were applied on three surfaces, including concrete, galvanized steel, and mosaic tiles. Mortality of adult insects was recorded after five days of exposure interval. Results revealed that in galvanized steel, and mosaic surfaces adding 20\% nanosilica to the Mamaghan DE caused the highest insecticidal activity of both insect species. In contrast, for the concrete surfaces, Mamaghan-15\% nanosilica had the same insecticidal activity as Mamaghan-20\%. The overall mortality of insects was 56.7, 66.6, and 48.9\% for T. confusum on concrete, galvanized steel, and mosaic surfaces, respectively. While for R. dominica, the mortality percentage was 83.3, 95.5, and 77.8\% on three tested surfaces, respectively, indicating that R. dominica was more sensitive to the DE than T. confusum. Our findings illustrated that nanosilica from sugarcane bagasse enhanced the insecticidal potential of Mamaghan DE against T. confusum and R. dominica compared with untreated Mamaghan DE.
The removal of pollutants from water should be followed by a proper treatment of the spent adsorbents. In this study, sugarcane bagasse/polydopamine (SB/PDA) adsorbents were applied in batch and column adsorption studies towards Cr(VI) ions. Adsorbents prepared with higher concentration of dopamine (4 g.L-1) led to more efficient adsorbents (SB/PDA4) and maximum adsorption capacity (qmax) of 138 mg.g- 1. X-ray photoelectron spectroscopy (XPS) analyses revealed that the adsorption mechanism involved ion-dipole and electrostatic interactions between Cr(VI) and the PDA functional groups. The spontaneous (Delta Gads -9 kJ mol-1) adsorption process was driven by an entropic gain related to the release of counter-ions and water molecules. Under optimized operational conditions, the maximum adsorption capacity in the fixed-bed column achieved the adsorption capacity of 141.7 mg.g-1. Considering the circular economy principles, the contaminated adsorbents were incorporated to cement pastes. No leaching of Cr(VI) from the cement/adsorbent samples could be detected over 64 days, and their mechanical behavior was comparable to the reference cement samples. The efficient removal of Cr(VI) from wastewater by SB/PDA adsorbents and the successful incorporation of spent adsorbents to cement demonstrated a sustainable management of liquid and solid wastes.
Sugarcane bagasse (SCB) is a major waste generated in the sugar production process, and efforts are being made to use it for a wide variety of applications. This work reports the green reduction of graphene oxide (RGO) using sugarcane bagasse extract (SBE), a renewable and sustainable resource. The RGO was characterized utilizing ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, Field emission scanning electron microscope and Energy dispersive spectrometer (FESEM-EDS), High-resolution transmission electron microscope (HRTEM) and X-ray photon spectroscopy (XPS). Characterization indicates that the synthesized RGO had an average thickness of around 034 nm, C/O ratio of about 4.27, UV-visibility at 270.5 nm, XRD peak at 2 theta = 26.5 degrees, and ID/IG ratio of approximately 1.16. Furthermore the RGO was tested by Cyclic Voltammograms (CVs) and demonstrated good cyclic stability and conductivity. Finally, the RGO was used to remove cadmium (Cd(II)) with the adsorption amount being nearly 24.47 mg/g. The new findings provide relevant insights into green reduction of oxide graphene by waste and using it to remediate metal ions. (C) 2018 Elsevier Ltd. All rights reserved.
Adsorption of 3-Aminopyridine (3AP) from simulated effluent using sugarcane bagasse activated carbon (SBAC) was studied based on batch and continuous operations. Characterization of synthesized SBAC was performed initially using BET and SEM analysis. Different batch experiments were performed to understand the effect of operating parameters such as initial concentration, pH, SBAC dose, time and temperature to understand the effect on the extent of adsorption. The maximum adsorption capacity for batch adsorption was established as 54.4 mg/g whereas the maximum extent of removal was 97.6 \% under optimized conditions. The observed data at equilibrium was found to be best fitted to Freundlich and Langmuir adsorption isotherms. Kinetic study revealed that pseudo-second order mechanism prevailed. Desorption of 3AP using ethanol showed good reuse efficacy for five cycles. Column adsorption experiments were also performed under varying SBAC bed height, concentration of 3AP and volumetric flow rate of 3AP solution to determine the breakthrough parameters. The fitting of the Yoon-Nelson and Thomas adsorption models to the obtained breakthrough data was studied and found to be satisfactory. Maximum adsorption capacity of SBAC for adsorption of 3AP in continuous operation was established as 65.6 mg/g. The obtained results demonstrated very good performance of SBAC for effective removal of 3AP in both batch and column operations. (c) 2020 Elsevier B.V. All rights reserved.
In this study, different metal-salt catalyzed pretreatment was presented to disorganize the obstinate structure by eliminating the majority of hemicellulose, fractional of lignin, and improve the enzymatic saccharification of sugarcane bagasse. With the accession of Tween 80 during enzymolysis, all metal-salt pretreated substrates presented higher glucose yields, especially for CuCl2. Furthermore, Tween 80 was added to the pretreatment, enhancing the elimination of hemicellulose and lignin, decreasing the degradation of sugars to inhibitors, and presenting superior performance on improving glucose yield. In addition, the maximum glucose yield of 88.0\% was achieved by using Tween 80 concomitantly with AlCl3 pretreatment and enzymolysis. It was also found that adding Tween 80 during pretreatment or/and enzymolysis after 24 h could liberate the similar glucose without Tween 80 after 72 h. However, the enhancement of Tween 80 at 6 h was higher than that at 72 h.
The addition of organic byproducts to soils is a vital source of essential nutrients for plant uptake. To reuse the nutrients effectively, there is a need to estimate the release patterns of nutrients from the byproducts. This study aimed to investigate the release patterns of nutrients {[
Sugarcane vinasse is a residue generated at a rate fifteen times greater than the ethanol production. Because of its high organic and micronutrient content, this residue is used as a fertilizer on sugarcane crops. However, when used in large quantities, vinasse can saturate the soil and contaminate nearby water resources by percolation and leaching. Given the proven toxic potential of in natura vinasse, the present study aimed to evaluate the toxic potential of leached sugarcane vinasse using Nile tilapia (Oreochromis niloticus) as a test organism. A bioassay was performed after vinasse percolation in laboratory soil columns. The bioassay included one control group containing fresh water and two treatment groups, the first exposed to a 2,5\% dilution of leached of vinasse and the second to a 2,5\% dilution of in natura vinasse. After exposure, histopathological analysis was performed in gills and livers, and the latter were labelled for HSP70 proteins. No significant changes were detected in the gills of the exposed fish. However, in the liver, both in natura and leached vinasse induced statistically significant histopathological changes. These changes include hydropic degeneration, cell boundary losses, pyknotic nuclei and cellular disorganization. HSP70 expression significant increase in liver of both treatment groups were observed, being higher for the in natura vinasse exposed group. Results suggested that both leached vinasse and in natura vinasse were toxic, its still able to provoke histological changes and induce the cytoprotective response in exposed fish liver, evidenced by a immunostaining of cellular stress proteins. Thus, in order to reduce its environmental impact, appropriated effluent disposal is essential.
In this work, sugarcane bagasse fiber, a waste product of agroindustry, was added to mortar mixes at different proportions looking to seal porosities so as to improve the resistance of concrete to carbonation and to improve its mechanical properties. To evaluate the behavior of bagasse fibers in the alkaline media typical of mortars, bagasse fibers were subjected to solutions with alkaline pH values, and their chemical structure and morphological behavior was evaluated using FTIR (Fourier transform infrared spectroscopy) and SEM (Scanning Electron Microscopy). Using mortar cylinders in an accelerated carbonation chamber to obtain results in short lapses, the compressive strength and the carbonation were evaluated. The FTIR analysis results indicate that pH values of 11 and 12 causes a delignification, while at pH 9 and 10, a swelling of the molecule occurs because of the addition of hydroxyl ions, behavior that is confirmed with SEM images. A clear effect of the fiber addition on the performance of concrete was observed as the carbonation front of 35 mm for the sample without fibers was reduced to 2 mm for the sample with 2\% fiber addition, resulting in an increase of 5 MPa in compressive strength. These results indicate that in the range of mortar pH, chemical changes occured over the sugarcane surface that could cause the growth of fibers and could partially seal the porosity in the mortars, thus enhancing its performance.
Cellulose degradation is inevitable during the production of furfural from biomass under the acidic systems; meanwhile, the simultaneous high yields of furfural and cellulose degradation product (5-HMF or levulinic acid) are hard to be achieved. To solve the problem and avoid the waste of cellulose, a method of producing furfural and preserving cellulosic residue was explored. Sugarcane bagasse was firstly pre-treated by phosphoric acid to obtain soluble xylo-oligosaccharides. And compared to the low furfural yields in phosphoric acid-water system based on response surface analysis, high furfural yields were obtained in the phosphoric acid-tetrahydrofuran (THF) system, meanwhile only trace cellulose was degraded. Furthermore, by a two-step rising temperature method, furfural yield reached to 66.59 mol\%, and cellulose was depolymerised into glucooligosaccharides. After recovery of furfural, this research also investigated the conversion of glucooligosaccharides catalysed by the residual phosphoric acid, and it was found levulinic acid and extremely high yields of formic acid generated at 200 degrees C.
The adsorption capacity of cellulose nanocrystals extracted from sugarcane bagasse using acid hydrolysis for methyl orange (MO) sequestration was investigated. The extracted nanocrystals were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and Fourier transform infra-red spectroscopy (FTIR). The cellulose nanocrystals were well identified by their features including well-defined pore spaces, predominant nano range of particles (0.045-0.082 mu m), greater crystallinity index from 1.09 to 1.21, disappearance of peaks at 1736 and 1429 cm(-1) in FTIR, and higher carbon content. A Two-fold improvement in monolayer adsorption capacity was obtained for cellulose nanocrystals (432.17 mg g(-1)), described by Langmuir isotherm, and for bagasse (170.99 mg g(-1)), described by Freundlich isotherm. Adsorption processes on both adsorbents were spontaneous, exothermic and followed pseudo-second order kinetics. Polynomial regression models appropriately predicted equations through which the effects of different batch adsorption parameters on MO removal were described, even with descriptions better than the experimentally generated data.
The bioconversion of xylose into xylitol using pH values of 4.0, 5.5, and 7.0 and tetracycline concentrations of 20 and 40 mg/L was carried out to verify the influence of these parameters on Candida guilliermondii metabolism for xylitol production. Experiments were performed with sugarcane bagasse hemicellulosic hydrolysate (48.5 g/L of xylose) in 125-mL Erlenmeyer flasks, at 30 degrees C, 200 rpm, during 88 h. The results demonstrated that the bioconversion of xylose into xylitol was significantly influenced by the pH. On the other hand, in media containing 20 or 40 mg/L of tetracycline, this bioconversion was not significantly affected. The best results of xylitol production were obtained in hemicellulosic hydrolysate without tetracycline, at pH 7.0. In these conditions, the maximum specific growth rate was 0.014/h and the yield factor of xylitol and volumetric productivity were 0.85 g/g and 0.70 g/L/h respectively. Xylitol and cell growth occurred simultaneously.
The effect of hydrothermal (HTP) and Ca(OH)(2) pretreatments on the biogas produced by the anaerobic digestion of sugarcane bagasse (SCB) was studied. HTP, Ca(OH)(2) and combination pretreatment had significant effects on hemicellulose and lignin degradation during pretreatment and methane yield through digestion. The highest biogas production observed in combination pretreatment HTP 180 + 8.5\% of SCB reached 318 mL/g Volatile Solids (VS), which were 47\% higher than the untreated SCB, with the highest methane content 69\% and highest lignin degradation 44\%. The functional groups and the structural changes in the pretreated SCB have also been analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analysis. Kinetic analysis of methane production potential from SCB was determined to compare ultimate methane yields and kinetic constants. The results of this research contribute useful information to improve the efficiency of anaerobic digestion of SCB by pretreatment.
Burning sugarcane (Saccharum officinarum) prior to manual harvest has been gradually replaced by a mechanized, green harvesting system that returns large amounts of crop residue (straw) to the soil surface in Brazil. A portion of the residue is required to protect soil against erosion, but some may be available as a feedstock for bioelectricity and cellulosic ethanol. Since excessive straw removal will degrade soil resources, it is imperative to determine the amount of straw needed for soil protection and to incorporate that information into decision-support tools so that straw management is sustainable. Our objective was to determine the amount of sugarcane straw needed to completely cover the soil surface. Photographic image analysis was used to quantify surface soil cover under 0 to 21 Mg ha(-1) of straw. Photos of 1-m(2) areas where various quantities of straw were homogeneously distributed were taken at a resolution of 8 megapixels (3264 x 2448 pixels) and then processed with ImageJ 1.52a software to obtain soil cover fraction. Straw layer thickness was also measured to the nearest millimeter using a ruler mounted in a rectangular acrylic box (0.5 m(2), 0.15 m height) into which the equivalent of 1 to 21 Mg ha(-1) of straw was placed. Soil cover increased exponentially, reaching more than 90\% with 3 Mg ha(-1) and full coverage with approximately 7 Mg ha(-1). Straw layer thickness increased linearly by 0.5 cm per Mg of straw left on the soil surface. Our findings will lead to more sustainable straw management practices that balance soil conservation and provision of feedstock for bioenergy production.
The saccharification of ozonated sugarcane bagasse (SCB) by enzymes from Myceliophthora thermophila JCP 1-4 was studied. Fungal enzymes provided slightly higher sugar release than commercial enzymes, working at 50 degrees C. Sugar release increased with temperature increase. Kinetic studies showed remarkable glucose release (4.99 g/L, 3\% w/w dry matter) at 60 degrees C, 8 h of hydrolysis, using an enzyme load of 10 FPU (filter paper unit). FPase and beta-glucosidase activities increased during saccharification (284\% and 270\%, respectively). No further significant improvement on glucose release was observed increasing the enzyme load above 7.5 FPU per g of cellulose. Higher dry matter contents increased sugars release, but not yields. The fermentation of hydrolysates by Saccharomyces cerevisiae provided glucose-to-ethanol conversions around to 63\%. (C) 2015 Elsevier Ltd. All rights reserved.
Due to mechanical harvesting large amount of straw is left in the field which implicates modification throughout the agriculture environment. This straw is beneficial for both soil and plant. However, there is no information about the sufficient quantity which can be used to achieve such effects and also whether it can be used in other sectors like electricity and ethanol production. Therefore, a research was designed with the objective to evaluate the effect of different amounts of straw on the development and productivity of sugarcane during the first and second ratoons. Treatments used in the experiment included: burned cane, 0\%, 25\%, 50\%, 75\% and 100\% (20 t ha(-1)) of sugarcane straw left on the soil surface. The tested variables included leaf area index (LAI), number, diameter, length and production of stems. Plants were evaluated at 60, 120, 180, 240 and 370 days after harvest (DAH) for the first ratoon and at 60, 120, 180, 240 and 270 DAH for the second ratoon. Replacing burned cane harvest system for soil management with straw promotes the development and productivity of sugarcane ratoons. Field managements with burned cane, total removal of the straw, or keeping 25\% of straw result in low number of tillers, leaf area index, stem diameter and productivity of sugarcane ratoons, under water stress conditions. Whereas keeping 50\% of straw mulch is enough to improve the growth and yield of sugarcane with drought occurrences, while the remaining 50\% can be used for second generation of ethanol production or electricity without damaging the crop yield. (C) 2017 Elsevier B.V. All rights reserved.
In this paper, sugarcane bagasse (SCB) was modified using phosphoric acid. The modified sugarcane bagasse (MSCB) has been used to remove 4-(2-pyridylazo) resorcinol (PAR) and Arsenazo-III (Ar-III) from liquid radioactive waste. The surface morphology and functional groups of the MSCB were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Adsorption ability of MSCB has been tested by batch mode through some relevant factors like initial pH, reaction time, initial coloring reagents (PAR and Ar-III) concentrations, and adsorbent weight. At adsorption equilibrium time 180 min and pH values of 3 and 1 for PAR and Ar-III; the maximum removal (\%) for both PAR and ArIII were 93 and 57\%, respectively. The adsorption isotherm data are representative well to Freundlich isotherm model. The mean free energy of adsorption, E (kJ/mol), has been estimated as 5.75 and 2.28 kJ/mol for PAR and Ar-III, respectively, which suggests that the adsorption occurred physically. The maximum adsorption capacity of MSCB for PAR and Ar-III is 96.62 and 15.18 mg/ g, respectively. The adsorption kinetics are better fitted by the pseudo-second-order model. The partial film along with intra-particle diffusion controlled the diffusion of coloring reagents from the solution bulk to the particle interior pores. Application of MSCB for removing PAR and Ar-III from simulated liquid radioactive waste containing U(VI) and Th(VI) ions has been achieved successfully.
India is the largest producer of sugar in the world and thereby produces tremendous amount of bagasse. Sugar industries utilize the bagasse to recover energy and the waste byproduct commonly termed as sugarcane bagasse ash (SBA) is discarded in landfills that impacts the environment at large. The SBA primarily contains calcium oxides, silica and aluminium ion that has the potential for developing sustainable building material. This study aims to find the effect of the industrial byproducts, micro silica (MS) and SBA on the durability and strength properties of M40 grade of concrete. In this study, the cement was partially substituted with varying percentages of SBA while MS was replaced by 10\% of weight of cement. The durability of the blended concrete against sulphate and chloride attack was assessed by immersing the cured concrete cubes in 5\% diluted (v/v) acids (sulfuric and hydrochloric). The loss in weight of the concrete cubes and compressive strength was examined at the end of 56 days and 90 days distinctly in both the acids. The blended concrete gives optimal resistance to sulphate and chloride attack when cement is replaced in the concrete with 10\% SBA and 10\% MS by weight. (C) 2020 The Authors. Published by Elsevier Ltd.
Recently, sugarcane bagasse ash (SBA), generated in boilers after combustion of sugarcane bagasse for cogeneration has been basically accepted as a pozzolanic material. In this study, SBA, which was first sieved through the No. 100 sieve (SBA-s) before burning at 600 degrees C, 700 degrees C, 800 degrees C for 1 h as post-treatment (denoted as SBA-600, SBA-700, SBA-800) was sequentially used as a partial replacement for Portland cement (i.e. 5\%, 10\%, 15\%, 20\% by weight) in casting blended mortars. Performance in fresh and hardened states of these mixes were examined and compared to that of the cement mortar (cement: sand of 1:2.75 and water-to-cement ratio of 0.57). The results indicate that the SBA-systems required more mixing water than Portland cement; whereas, blended pastes with a part of re-burnt ash manifested an acceleration of setting time compared to that with SBA-s. In addition, mortars prepared with SBA-700 or SBA-800 at replacement rates of 5\% and 10\% for cement showed the lowest porosity, the best both of mechanical strength and durability (in terms of sulphate resistance, surface resistivity). SEM analysis verifies that a dense phase was observed for the matrix of blended mortars contained 5-10\% SBA-700 or SBA-800.
Alkaline hydrogen peroxide (AHP) treatment affected physical and chemical properties of sugarcane bagasse (SB). AHP treatment can improve all its physical properties. The brightness, water-holding capacity (WHC), and oil-binding capacity (OBC) of SB were increased by 34, 96, and 55\%, respectively. Lignin was removed from SB by 53\%. Colour of Solka Floc((R)) 900, a commercial dietary fibre, was pure white (L = 93.51); WHC and OBC were 8.61 g water/g sample and 7.34 g oil/g sample, respectively. The results showed a highly positive correlation between particle size reduction,of each dietary fibre (DF), WHC and OBC. While density showed a negative correlation, densities of AHP-SB and Solka Floc((R)) 900 were increased, with particle size reduction, from 1.06 to 1.34 and from 1.09 to 1.28, respectively. At 5\% of AHP-SB and Solka Floc((R)) 900 substitution in bread, reductions of loaf volume and softness of bread were observed in direct opposition to particle size reduction. The most acceptable breads contained 5\% of AHP-SB and Solka Floc((R)) 900 when the particle sizes were < 0.075 and < 0.106 mm, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.
This work evaluates the technical performance and environmental impacts, when sugarcane bagasse is applied as reinforcement of polypropylene in a component instead neat polypropylene (PP). To achieve the goals of this study, the tensile and flexural properties and Life Cycle Assessment (LCA) as a function of fiber content were performed. In addition, different end-of-life (EOL) options for natural fiber composites were proposed, including incineration, recycling (with economic reuse) and discharging (landfill). Besides the good mechanical properties, natural fiber composites showed great environmental performance during the entire life cycle, mainly in the cultivation phase, when sugarcane consumes carbon while growing, contributing to global warming decreases. As a conclusion, sugarcane bagasse fibers production results in lower environmental impacts compared to neat PP and the recycling with economic reuse of sugarcane bagasse-PP composite was the best alternative to minimize environmental impacts after the end-of-life.
Sugarcane bagasse was pretreated with diluted sulfuric acid to obtain sugarcane bagasse hemicellulosic hydrolysate (SBHH). Experiments were conducted in laboratory and semi-pilot reactors to optimize the xylose recovery and to reduce the generation of sugar degradation products, as furfural and 5-hydroxy-methylfurfural (HMF). The hydrolysis scale-up procedure was based on the H-Factor, that combines temperature and residence time and employs the Arrhenius equation to model the sulfuric acid concentration (100 mg(acid)/g(dm)) and activation energy (109 kJ/mol). This procedure allowed the mathematical estimation of the results through simulation of the conditions prevailing in the reactors with different designs. The SBHH obtained from different reactors but under the same H-Factor of 5.45 +/- 0.15 reached similar xylose yield (approximately 74\%) and low concentration of sugar degradation products, as furfural (0.082 g/L) and HMF (0.0071 g/L). Also, the highest lignin degradation products (phenolic compounds) were rho-coumarilic acid (0.15 g/L) followed by ferulic acid (0.12 g/L) and gallic acid (0.035 g/L). The highest concentration of ions referred to S (3433.6 mg/L), Fe (554.4 mg/L), K (103.9 mg/L), The H-Factor could be used without dramatically altering the xylose and HMF/furfural levels. Therefore, we could assume that H-Factor was directly useful in the scale-up of the hemicellulosic hydrolysate production. (C) 2009 Published by Elsevier Ltd.
Fructooligosaccharides (FOS) can be used as feed prebiotics, but are limited by high production costs. In this study, low-cost sugarcane molasses was used to produce whole-cell biocatalysts containing transfructosylating enzymes by Aureobasidium pullulans FRR 5284, followed by FOS production from molasses using the whole-cells of A. pullulans. A. pullulans in molasses-based medium produced cells and broth with a total transfructosylating activity of 123.6 U/mL compared to 61.0 and 85.8 U/mL in synthetic molasses-based and sucrose-based media, respectively. It was found that inclusion of glucose in sucrose medium reduced both transfructosylating and hydrolytic activities of the produced cells and broth. With the use of pure glucose medium, cells and broth had very low levels of transfructosylating activities and hydrolytic activities were not detected. These results indicated that A. pullulans FRR 5284 produced both constitutive and inducible enzymes in sucrose-rich media, such as molasses while it only produced constitutive enzymes in the glucose media. Furthermore, treatment of FOS solutions generated from sucrose-rich solutions using an invertase-deficient Saccharomyces yeast converted glucose to ethanol and acetic acid and improved FOS content in total sugars by 20-30\%. Treated FOS derived from molasses improved the in vitro growth of nine probiotic strains by 9-63\% compared to a commercial FOS in 12 h incubation. This study demonstrated the potential of using molasses to produce FOS for feed application.
Continuous fermentation of sugarcane bagasse hemicellulosic hydrolysate by the yeast Candida guilliermondii FTI 20037 was used for xylitol production from xylose. Experiments were carried out in a reactor with 1.25 1 of treated hydrolysate, at 30 degreesC and 300 rpm. A 2 2 full-factorial central composite design was employed for experimental study and analysis of the results. A statistical analysis of the results showed that the effects of the pH and dilution rate (D), the interactions between these variables and the second-order effect of D on the xylitol volumetric productivity (Q(p)) were significant at a 95\% confidence level. The second-order effect of pH was also significant at a 90\% confidence level. The k(L)a effect on the Q, was not significant. A volumetric productivity of 0.68 g/l h, representing 95.8\% of the predicted value (0.72 g/l h), was obtained. (C) 2002 Elsevier Science Ltd. All rights reserved.
In this work, the green material based on epoxidized natural rubber (ENR) and modified cellulose were prepared through a completely eco-friendly procedure. Cellulose was extracted from sugarcane bagasse through removal of hemicellulose and lignin by a simple method. Thereafter, purified cellulose was modified by graft-copolymerization of acrylonitrile in the presence of ammonium persulfate initiator in emulsion state. The obtained cellulose was blended with ENR in molten state. The structural characterization through FT-IR spectroscopy confirmed that polyacrylonitrile was successfully grafted on cellulose. The optimal condition for graft-copolymerization was found at 5 degrees C and ammonium persulfate concentration of 0.022 mol/kg cellulose, at which the highest nitrogen content of the resulting material was 2.82 wt\%. The blend of ENR cellulose-graft-polyacrylonitrile of which the nitrogen content is 2.82 wt\% (Cel-Pan-2.82) expressed the outstanding properties in term of tensile strength, hardness, thermal resistance, and self-cleaning. The tensile strength and hardness of the blend containing 10 wt\% of Cel-Pan-2.82 was 6.5 MPa and 49.0, respectively; those of the blend containing 20 wt\% of Cel-Pan-2.82 was 5.5 MPa and 59.5, respectively. The mechanical properties of the blends were better than those of ENR. The initial decomposition temperature of the blends was 150 degrees C higher than that of ENR. The contact angle of the blends containing Cel-Pan-2.82 was about 12-25 degrees higher than that of ENR, which confirmed the waterproof of the blends. SEM observation confirmed the fine dispersion of Cel-Pan-2.82 in ENR. The improvement in the properties of the blends was attributed to the effect of polyacrylonitrile which enhanced the compatibility of ENR phase and cellulose phase.
In order to understand the role of untreated sugarcane bagasse ash (UtSCBA) in chloride binding of ternary concretes prepared with fly ash, an experimental program was carried out. Concrete specimens containing only Portland cement, Portland cement + fly ash and Portland cement + fly ash + UtSCBA were manufactured. After curing these specimens were exposed to a chloride solution for 3000 days. After exposure, a microstructural characterization using scanning electron microscopy and X-Ray diffraction was conducted. The compressive strength, electrical resistivity of the concretes and percentage of voids, were also obtained, while information on chloride binding was obtained from the difference between the amount of total and free chlorides. Diffractograms showed that chlorides chemically reacted with the Afm and Aft phases of all concretes to form Friedel's salt. In summary, ternary concretes containing UtSCBA showed the highest chloride-binding capacity.