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The necessity for the reduction in greenhouse gas emissions, the growing demand for the improvement of biorefinery technologies, and the development of new biorefining concepts oblige us as a society, and particularly us, as scientists, to develop novel biorefinery approaches. The purpose of this study is to thoroughly evaluate the leftover lignocellulosic (LC) biomass obtained after the manufacture of 2-furaldehyde, with the intention of further valorizing this resource. This study demonstrates that by using thermomechanical and alkaline peroxide mechanical pulping techniques, birch wood chips can be used in the new biorefinery processing chain for the production of 2-furaraldehyde, acetic acid, and cellulose pulp. In addition, the obtained lignocellulosic residue is also characterized. To produce a lignocellulosic material without pentoses and with the greatest amount of cellulose fiber preserved for future use, a novel bench-scale reactor technology is used. Studies were conducted utilizing orthophosphoric acid as a catalyst to deacetylate and dehydrate pentose monosaccharides found in birch wood, converting them to 2-furaldehyde and acetic acid. The results showed that, with the least amount of admixtures, the yields of the initial feedstock’s oven-dried mass (o.d.m.) of 2-furaldehyde, acetic acid, and lignocellulose residue ranged from 0.04 to 10.84%, 0.51 to 6.50%, and 68.13 to 98.07%, respectively, depending on the pretreatment conditions utilized. The ideal 2-furaldehyde production conditions with reference to the purity and usability of cellulose in residual lignocellulosic material were also discovered through experimental testing. The experiment that produced the best results in terms of 2-furaldehyde yield and purity of residual lignocellulose used a catalyst concentration of 70%, a catalyst quantity of 4%, a reaction temperature of 175 °C, and a treatment period of 60 min. It was possible to create pulp with a tensile index similar to standard printing paper by mechanically pulping the necessary LC residue with alkaline peroxide, proving that stepwise 2-furaldehyde production may be carried out with subsequent pulping to provide a variety of value-added goods.

Production of high value-added products from lignocelluloses is an economically sustainable alternative to decreasing dependence on fossil fuels and making the chemical processes environmentally friendly. In this study, different methodologies of alkaline (Ca(OH)2 and NaOH), dilute acid (10%w/w H2SO4), hydrogen peroxide (H2O2), alkaline peroxide oxidation (H2O2/Ca(OH)2 and H2O2/NaOH), and molten hydrated salt (MHS) mediated (ZnCl2.4H2O) pretreatments were employed in the hydrolysis of corncob amenable to enzymatic hydrolysis. Optimal enzyme hydrolysis temperature (considering 45 and 50 ℃) and time (2, 24, 72, and 96 h) were investigated for each pretreatment procedure to ascertain the concentrations of glucose, xylose, and total sugar present in the corncob. At 45 ℃ and 96 h, NaOH alkaline pretreatment achieved the best optimum total sugar production of 75.54 mg/mL (about 54% and 88% increments compared to dilute acid pretreatment (35.06 mg/mL total sugars) and MHS (9.32 mg/mL total sugar) pretreatment respectively). In this study, total sugars production increased appreciably at 45 ℃ and longer hydrolysis period (96 h) compared to hydrolysis at 50 ℃ (with maximum total sugars production of 18.00 mg/mL at 96 h). Scanning electron microscopic imaging of the untreated and treated samples displayed cell wall distortion and surface disruptions.

The necessity for the reduction in greenhouse gas emissions, the growing demand for the improvement of biorefinery technologies, and the development of new biorefining concepts oblige us as a society, and particularly us, as scientists, to develop novel biorefinery approaches. The purpose of this study is to thoroughly evaluate the leftover lignocellulosic (LC) biomass obtained after the manufacture of 2-furaldehyde, with the intention of further valorizing this resource. This study demonstrates that by using thermomechanical and alkaline peroxide mechanical pulping techniques, birch wood chips can be used in the new biorefinery processing chain for the production of 2-furaraldehyde, acetic acid, and cellulose pulp. In addition, the obtained lignocellulosic residue is also characterized. To produce a lignocellulosic material without pentoses and with the greatest amount of cellulose fiber preserved for future use, a novel bench-scale reactor technology is used. Studies were conducted utilizing orthophosphoric acid as a catalyst to deacetylate and dehydrate pentose monosaccharides found in birch wood, converting them to 2-furaldehyde and acetic acid. The results showed that, with the least amount of admixtures, the yields of the initial feedstock's oven-dried mass (o.d.m.) of 2-furaldehyde, acetic acid, and lignocellulose residue ranged from 0.04 to 10.84%, 0.51 to 6.50%, and 68.13 to 98.07%, respectively, depending on the pretreatment conditions utilized. The ideal 2-furaldehyde production conditions with reference to the purity and usability of cellulose in residual lignocellulosic material were also discovered through experimental testing. The experiment that produced the best results in terms of 2-furaldehyde yield and purity of residual lignocellulose used a catalyst concentration of 70%, a catalyst quantity of 4%, a reaction temperature of 175 °C, and a treatment period of 60 min. It was possible to create pulp with a tensile index similar to standard printing paper by mechanically pulping the necessary LC residue with alkaline peroxide, proving that stepwise 2-furaldehyde production may be carried out with subsequent pulping to provide a variety of value-added goods. [ABSTRACT FROM AUTHOR]

In this study, the structural modification of Siam weed (Chromolaena odorata) was performed using NaOH–H2O2- and Ca(OH)2–H2O2-based oxidative pretreatment for the enzymatic conversion of the biomass to a biocommodity, reducing sugar (RS). Pretreatment of raw sample was evaluated at temperatures of 60°C, 70°C, 80°C, 90°C for different time intervals of 3, 6, 9, 12 h in alkaline medium (NaOH or Ca(OH)2). The effects of pretreatment time and temperature were considered in obtaining the optimum conditions. The optimum conditions for NaOH–H2O2 was obtained at 70°C and 3 h with a maximum cellulose content of 44.29%(w/w), lignin content reduced to 21.09% from the initial raw value of 24.2%. Pretreatment with Ca(OH)2–H2O2 resulted in the optimum conditions obtained to be 70°C for 3 h with a cellulose content of 47.18%. Enzymatic hydrolysis on the pretreated biomass at the optimum conditions showed NaOH–H2O2-treated sample yielded 424.35 mg equivalent glucose/g biomass of RS while Ca(OH)2–H2O2-treated sample yielded 335.81 mg equivalent glucose/g biomass of RS. The untreated raw sample yielded 68.75 mg equivalent glucose/g biomass of RS. Consequently, NaOH–H2O2 pretreatment displayed a higher efficiency than Ca(OH)2–H2O2 pretreatment. Stereomicroscopic and scanning electron microscopic imaging of the treated and untreated samples revealed morphological disruptions brought about by the treatments.

Lignocellulose materials, essentially consisting of lignin, cellulose and hemicelluloses, are abundant sources of fermentable sugars. The bast fiber of Crotalaria juncea (Sunn hemp), a native cover crop of India, was used as feedstock for this study. The primary objective of this study was to add value to the waste C. juncea bast fiber. The same was achieved by pretreating the waste fiber using alkaline peroxide solution at various process conditions. The optimal process condition for alkaline peroxide pretreatment was identified for the fiber to pretreatment solution (S/S) ratio of 1/40 at 50°C for 5h with respect to all response variables (lignin removal, hemicellulose recovery, recovery of solid pretreated material, and crystallinity of lignocellulose). Three-way ANOVA results revealed that S/S ratio had no significant effect; whereas, both temperature and time, and the combination of parameters, exhibited significant effect on response variables. The characteristic peaks associated with lignin and cellulose demonstrated a higher amount of lignin removal and increased cellulose content with elevated treatment time. Autoclave assisted pretreatment proved to be inefficient due to removal of lower amount of lignin in addition to higher hemicellulose degradation. On the other hand, pretreatment using ultrasound was found to be most effective in removing lignin, liberating hemicelluloses along with diminition in cellulose crystallinity. [ABSTRACT FROM AUTHOR]

Effects of alkaline peroxide (AP) treatment on chemical compositions and characteristics of lignocellulosic nanofibrils (LCNFs) were investigated. The AP treatment was conducted on a wood powder (Liriodendron tulipifera) at 80 °C for 1 or 5 h with different hydrogen peroxide concentrations (0.2 to 12 wt%) to selectively remove hemicelluloses and lignin. The treated wood powder was then defibrillated using wet-disk milling (WDM). The hemicelluloses and lignin in the LCNFs were successfully reduced to the ranges of 6.0% to 23.6% and 13.0% to 30.0%, respectively, depending upon the AP treatment conditions. The defibrillation efficiency improved as the hemicelluloses and lignin were removed, which reduced the LCNF dimensions. The filtration time increased with decreasing lignin and hemicellulose contents. The cellulose crystallinity and surface area of the LCNFs increased with decreasing lignin and hemicellulose contents. The tensile strength and water contact angles of the nanopaper handsheets increased, and the paper's color became whiter as the lignin content decreased. [ABSTRACT FROM AUTHOR]

Production of high value-added products from lignocelluloses is an economically sustainable alternative to decreasing dependence on fossil fuels and making the chemical processes environmentally friendly. In this study, different methodologies of alkaline (Ca(OH)2 and NaOH), dilute acid (10%w/w H2SO4), hydrogen peroxide (H2O2), alkaline peroxide oxidation (H2O2/Ca(OH)2 and H2O2/NaOH), and molten hydrated salt (MHS) mediated (ZnCl2.4H2O) pretreatments were employed in the hydrolysis of corncob amenable to enzymatic hydrolysis. Optimal enzyme hydrolysis temperature (considering 45 and 50 °) and time (2, 24, 72, and 96 h) were investigated for each pretreatment procedure to ascertain the concentrations of glucose, xylose, and total sugar present in the corncob. At 45 ° and 96 h, NaOH alkaline pretreatment achieved the best optimum total sugar production of 75.54 mg/mL (about 54% and 88% increments compared to dilute acid pretreatment (35.06 mg/mL total sugars) and MHS (9.32 mg/mL total sugar) pretreatment respectively). In this study, total sugars production increased appreciably at 45 ° and longer hydrolysis period (96 h) compared to hydrolysis at 50 ° (with maximum total sugars production of 18.00 mg/mL at 96 h). Scanning electron microscopic imaging of the untreated and treated samples displayed cell wall distortion and surface disruptions. [ABSTRACT FROM AUTHOR]

This study investigated the performance of recycled polypropylene (RPP)/peanut shell powder (PSP) composites with untreated PSP and treated PSP with alkaline peroxide. The RPP/PSP and RPP/PSPH2O2 composites were prepared by melt mixing and compression molding at different PSP loadings (10 wt.% to 40 wt.%). The samples were characterized by processing properties, tensile properties, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and water absorption behavior. The treated PSP enhanced the stabilization torque, tensile strength, elongation at break, tensile modulus, and water absorption of RPP/PSP-H2O2 composites. FTIR spectra and SEM showed that the elimination of lignin content strongly influenced the fractured surface and chemical characteristics of the RPP/PSP-H2O2 composites. [ABSTRACT FROM AUTHOR]

The effect of pretreatments by hydrothermolysis (180 °C; 15 min) and alkaline delignification (NaOH 5M; H 2 O 2 1%; 24 h) in citrus peel waste (CPW) was evaluated, as well as the effect on H 2 , organic acids and alcohols production, in addition to characterization of the microbial community involved in fermentation. Batch reactors at 37 °C were operated with 3 gTVS/L of CPW with allochthonous consortium (UASB reactor sludge; 2 gTVS/L) and autochthonous of CPW (1.5 gTVS/L) as inocula. H 2 production was higher in reactors with in natura CPW (13.31 mmol/L) compared to hydrothermolysis (8.19 mmol/L) and alkaline delignification (7.27 mmol/L). The acetogenic pathway was predominant in the in natura CPW (4,355 mg/L acetic acid). The most abundant genera in the in natura CPW and after hydrothermolysis were Clostridium (18.97 and 12.90%, respectively) and Ruminiclostridium (16.65 and 1.04%, respectively) commonly related to cellulolytic bacteria and/or H 2 production. Image 1 • CPW delignification was higher in hydrothermolysis than in alkaline pretreatment. • Lower limonene content in CPW after hydrothermolysis and alkaline delignification. • Effect of hydrothermolysis on the microbial community involved in CPW fermentation. • Clostridium as the most abundant genera evolved in CPW anaerobic digestion. • Acetic acid was the major organic acid obtained through CPW biodegradation. [ABSTRACT FROM AUTHOR]

Abstract: The cellulose content of substrate is one of the most important factors for ethanol production from lignocellulose. To increase the cellulose content of substrate and ethanol yield in simultaneous saccharification and fermentation (SSF), a pretreatment method coupling steam explosion with alkaline peroxide for wheat straw was studied. After the complex pretreatment, the cellulose content in wheat straw increased from 31.5% to 67.2%. In the hydrolysate of wheat straw pretreated with the complex method and steam explosion, the glucose concentration was 110.9g/L and 67.8g/L, respectively. The optimal conditions for SSF were 40°C, 120h, cellulase loading 40FPU/(g wheat straw), yeast inoculum 10% (v/v) and substrate concentration 16.7% (w/v). Under the optimal conditions, the total ethanol concentration in SSF of wheat straw pretreated with steam explosion and alkaline peroxide reached 51.5g/L, and an overall yield of 81.1% was obtained. [Copyright &y& Elsevier]

Treatment of dewaxed oil palm frond fiber; fast-growing poplar wood; maize stems; and barley, wheat, rice, and rye straws with 2.0% H2O2 at pH 11.6 for 16 hr at 45°C solubilized 85.7%, 49.5%, 78.2%, 79.7%, 87.1%, 92.7%, and 79.4% of the original hemicelluloses and 72.1%, 24.9%, 87.3%, 70.9%, 85.7%, 88.6%, and 89.8% of the original lignin, respectively. The results indicated that hydrogen peroxide at pH 11.6 had a significant effect on the release of hemicelluloses and delignification from oil palm frond fiber and cereal straws such as maize stems and barley, wheat, rice, and rye straws under the condition used. All the hemicellulosic preparations were much lighter in color and had relatively lower amounts of associated lignin than those obtained using traditional alkaline extraction in the absence of peroxide from the corresponding lignified materials. Xylose is the dominant sugar component in the hemicellulosic preparations isolated from oil palm frond fiber, fast-growing poplar wood, maize stems, and barley, wheat and rye straws, whereas the hemicelluloses obtained from rice straw are rich in glucose and xylose. The seven hemicellulosic samples were also studied by fourier transform infrared(FT-IR} and 1H- and 13C-nuclear magnetic resonance(NMR) spectroscopy, gel permeation chromatography(GPC), and thermal analysis. [ABSTRACT FROM AUTHOR]

Abstract: Oil palm empty fruit bunches (EFB) are a lignocellulosic by product generated by palm oil mills. Delignified EFB fiber is a potential source of inexpensive hemicellulose, a substrate that is easily hydrolyzed to sugars for use in diverse biotechnological processes. The conditions for maximized selective removal of lignin from EFB fiber via separate treatments with alkaline peroxide and peracetic acid, were established such that the loss of hemicellulose was kept to a minimum. The amount of a reagent used in delignification, the temperature and the length of treatment, were optimized using a combination of Box–Behnken experimental design and the response surface method. Treatments with peracetic acid always left behind more hemicellulose and removed more lignin compared with the treatments involving alkaline peroxide. Under the best conditions (20 cm3 peracetic acid per g EFB, 35 °C, reaction time of 9 h), hemicellulose, cellulose and acid insoluble lignin constituted (dry weight basis) nearly 36%, 47% and ∼16%, respectively, of the treated acetone-washed extractive-free EFB fiber. Approximately 53% of the lignin was removed, but nearly all the hemicellulose was retained. [Copyright &y& Elsevier]

Background: Pretreatment is a critical step in the conversion of lignocellulose to fermentable sugars. Although many pretreatment processes are currently under investigation, none of them are entirely satisfactory in regard to effectiveness, cost, or environmental impact. The use of hydrogen peroxide at pH 11.5 (alkaline hydrogen peroxide (AHP)) was shown by Gould and coworkers to be an effective pretreatment of grass stovers and other plant materials in the context of animal nutrition and ethanol production. Our earlier experiments indicated that AHP performed well when compared against two other alkaline pretreatments. Here, we explored several key parameters to test the potential of AHP for further improvement relevant to lignocellulosic ethanol production. Results: The effects of biomass loading, hydrogen peroxide loading, residence time, and pH control were tested in combination with subsequent digestion with a commercial enzyme preparation, optimized mixtures of four commercial enzymes, or optimized synthetic mixtures of pure enzymes. AHP pretreatment was performed at room temperature (23°C) and atmospheric pressure, and after AHP pretreatment the biomass was neutralized with HCl but not washed before enzyme digestion. Standard enzyme digestion conditions were 0.2% glucan loading, 15 mg protein/g glucan, and 48 h digestion at 50°C. Higher pretreatment biomass loadings (10% to 20%) gave higher monomeric glucose (Glc) and xylose (Xyl) yields than the 2% loading used in earlier studies. An H2O2 loading of 0.25 g/g biomass was almost as effective as 0.5 g/g, but 0.125 g/g was significantly less effective. Optimized mixtures of four commercial enzymes substantially increased post-AHP-pretreatment enzymatic hydrolysis yields at all H2O2 concentrations compared to any single commercial enzyme. At a pretreatment biomass loading of 10% and an H2O2 loading of 0.5 g/g biomass, an optimized commercial mixture at total protein loadings of 8 or 15 mg/g glucan gave monomeric Glc yields of 83% or 95%, respectively. Yields of Glc and Xyl after pretreatment at a low hydrogen peroxide loading (0.125 g H2O2/g biomass) could be improved by extending the pretreatment residence time to 48 h and readjusting the pH to 11.5 every 6 h during the pretreatment. A Glc yield of 77% was obtained using a pretreatment of 15% biomass loading, 0.125 g H2O2/g biomass, and 48 h with pH adjustment, followed by digestion with an optimized commercial enzyme mixture at an enzyme loading of 15 mg protein/g glucan. Conclusions: Alkaline peroxide is an effective pretreatment for corn stover. Particular advantages are the use of reagents with low environmental impact and avoidance of special reaction chambers. Reasonable yields of monomeric Glc can be obtained at an H2O2 concentration one-quarter of that used in previous AHP research. Additional improvements in the AHP process, such as peroxide stabilization, peroxide recycling, and improved pH control, could lead to further improvements in AHP pretreatment. [ABSTRACT FROM AUTHOR]

So far, a large number of pretreatment methods have garnered significant attention aimed only at optimizing the reducing sugar and bioethanol yields. This study however, carried out pretreatment of sugarcane bagasse (SCB) using hydrothermal, organosolv, alkaline and alkaline peroxide pretreatment methods comparing their process performance. An evaluation of the energy consumption parameter during pretreatment showed lowest energy use (0.619 kWh/kg) during 5% alkaline peroxide pretreatment. The energy efficiency (0.162 kg bioethanol/kWh) was thus highest whereas the waste generation was lowest (38.895 kg waste/kg bioethanol) during alkaline peroxide pretreatment process. The solid biomass was utilized for enzymatic saccharification and bioethanol fermentation using SSF. Maximum enzyme efficiency and bioethanol yields achieved were 85.02% and 0.101 kg bioethanol/kg biomass respectively. Process performance evaluation can be projected to open up a new avenue for practical implementations of life cycle analysis (LCA) and techno-economic assessment aiding the circular bio-economy approach. [Display omitted] • Chemical pretreatment technologies investigated for process performance evaluation. • Energy efficiency and waste generation used to evaluate process performance. • 0.162 kg bioethanol/kWh- energy efficiency during alkaline peroxide pretreatment. • Also, lowest waste generation (38.895 kg waste/kg bioethanol) was recorded. • NaOH and H 2 O 2 at 5% (w/w) chemical concentration was most effective pretreatment. [ABSTRACT FROM AUTHOR]

Biomass recalcitrance is considered to be one of the impediments in bioconversion of lignocellulosic biomass (LCB) to sugars. Rice straw, a potential lignocellulosic waste, owing to the surplus availability, renewability and high carbohydrate content was used as a model LCB in the present study. The alkaline hydrogen peroxide-assisted wet air oxidation (APWAO) was evaluated as plausible pretreatment for rice straw based on the 2-factorial experimental design with a goal to reduce biomass recalcitrance by enhancing the cellulose recovery, hemicellulose solubilization, lignin removal and concomitantly generating limited degradation products. APWAO resulted in an overall cellulose recovery ranging from 80.54 to 93.02%, hemicellulose solubilization of 36.44-82.08% and lignin removal of 65.95-81.11% (all on w/w basis) respectively and absence of potent inhibitors viz. furfural and 5-hydroxymethylfurfural. The statistically significant pretreatment factors that affected each of these responses were assessed and optimum pretreatment conditions were determined to be biomass soaking in 0.5% HO for 14 h succeeded by wet air oxidation (WAO) at 190 °C, 6 bar, 20 min by multi-objective numerical optimization. Further, the morphological and structural changes occurring as a result of pretreatment were scrutinized using SEM and FT-IR. APWAO further ensued in enhanced cellulose accessibility during enzymatic saccharification indicated by the glucose yield ranging from 113.97 to 200.34 g/kg untreated rice straw. Thus, the combined pretreatment (APWAO) i.e. pre-soaking in alkaline HO followed by WAO was shown to enhance glucose yields owing to significant delignification. [ABSTRACT FROM AUTHOR]

Developing economical and sustainable fractionation technology of lignocellulose cell walls is the key to reaping the full benefits of lignocellulosic biomass. This study evaluated the potential of metal chloride-assisted p-toluenesulfonic acid (p-TsOH) hydrolysis at low temperatures and under acid concentration for the co-production of sugars and lignocellulosic nanofibrils (LCNF). The results indicated that three metal chlorides obviously facilitated lignin solubilization, thereby enhancing the enzymatic hydrolysis efficiency and subsequent cellulose nanofibrillation. The CuCl2-assisted hydrotropic pretreatment was most suitable for delignification, resulting in a relatively higher enzymatic hydrolysis efficiency of 53.2%. It was observed that the higher residual lignin absorbed on the fiber surface, which exerted inhibitory effects on the enzymatic hydrolysis, while the lower lignin content substrates resulted in less entangled LCNF with thinner diameters. The metal chloride-assisted rapid and low-temperature fractionation process has a significant potential in achieving the energy-efficient and cost-effective valorization of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

In this study, the structural modification of Siam weed (Chromolaena odorata) was performed using NaOH-H2O2- and Ca(OH)2-H2O2-based oxidative pretreatment for the enzymatic conversion of the biomass to a biocommodity, reducing sugar (RS). Pretreatment of raw sample was evaluated at temperatures of 60°C, 70°C, 80°C, 90°C for different time intervals of 3, 6, 9, 12 h in alkaline medium (NaOH or Ca(OH)2). The effects of pretreatment time and temperature were considered in obtaining the optimum conditions. The optimum conditions for NaOH-H2O2 was obtained at 70°C and 3 h with a maximum cellulose content of 44.29%(w/w), lignin content reduced to 21.09% from the initial raw value of 24.2%. Pretreatment with Ca(OH)2-H2O2 resulted in the optimum conditions obtained to be 70°C for 3 h with a cellulose content of 47.18%. Enzymatic hydrolysis on the pretreated biomass at the optimum conditions showed NaOH-H2O2-treated sample yielded 424.35 mg equivalent glucose/g biomass of RS while Ca(OH)2-H2O2-treated sample yielded 335.81 mg equivalent glucose/g biomass of RS. The untreated raw sample yielded 68.75 mg equivalent glucose/g biomass of RS. Consequently, NaOH-H2O2 pretreatment displayed a higher efficiency than Ca(OH)2-H2O2 pretreatment. Stereomicroscopic and scanning electron microscopic imaging of the treated and untreated samples revealed morphological disruptions brought about by the treatments. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA) was produced from oil palm empty fruit bunch (OPEFB) pretreated in two different ways: (1) a two-step treatment with peracetic acid (PA) and alkaline peroxide (AP); and (2) an ammonia soak pretreatment. The pretreated material was subjected to acid hydrolysis (5% w/v sulfuric acid, 125 °C to 175 °C, 120 min) to produce LA. Compared to the ammonia treatment, the two-step PA–AP pretreatment was better in removing lignin from OPEFB, and resulted in a higher LA yield based on the mass of the pretreated OPEFB. On a mass basis, the LA yield was 31.1% on pretreated OPEFB, that had been pretreated using the PA–AP process, but only 16.7% from the biomass treated using the ammonia process. The kinetics of acid-catalyzed production of LA from the pretreated OPEFB were investigated to develop a mathematical model for predicting the conversion of cellulose to the intermediates (glucose, 5-hydroxymethylfurfural), and the final product, LA. The hydrolysis of cellulose to glucose was found to be the rate-controlling step in acid-catalyzed production of LA, confirming the importance of the delignification pretreatment in making cellulose more amenable to hydrolysis. During the two-stage acid hydrolysis, the reaction at 175 °C for 15 min in the first stage, followed by 125 °C for 105 min in the second stage, resulted in LA molar yield (based on cellulose) of ∼40%. This was comparable to the yield obtained if both steps were performed at 150 °C for a total of 120 min. [ABSTRACT FROM AUTHOR]

Comparisons were studied for untreated and pretreated bagasse with dilute alkaline peroxide and steam for bioethanol production by simultaneous saccharification and fermentation (SSF) process in a continuous stirred batch bioreactor using fungi Fusarium oxysporum. The optimum parameters for bioethanol fermentation were: time, 48 h; pH, 6.0; temperature, 50°C; stirring speed, 35 rpm; and bagasse loading, 35 g/L. Maximum concentrations of bioethanol at optimum fermentation process parameters were 18.73 g/L, 19.69 g/L and 20.45 g/L for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. Maximum yields of bioethanol were 0.706 g/g, 0.734 g/g and 0.764 g/g of bagasse at optimum parameters for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The sp. growth rate (µ) of fungi Fusarium oxysporum was determined at 5.91 s−1, 6.25 s−1 and 7.11 s−1 and maximum sp. growth rate (µmax) was calculated at 11.81 s−1, 12.50 s−1 and 14.22 s−1 for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The sp. enzyme activity (ν) was found at 138a0 min−1, 1565 min−1 and 1695 min−1 and maximum sp. activity (νmax) was calculated at 2760 min−1, 3130 min−1 and 3390 min−1 for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The first order rate constants (k) were determined as 0.12 h−1, 0.14 h−1 and 0.156 h−1 for untreated, steam and dilute alkaline peroxide pretreated bagasse for fermentation in continuous stirred batch bioreactor, respectively. [ABSTRACT FROM PUBLISHER]

Lignocellulose nanofibrils (LCNFs), as an emerging member of the green nanofibril family, have tremendous potential in improving the dispersibility, adsorption and photogenerated carrier separation efficiency of BiOBr because of the combination of the advantages of nanocellulose (NC) and nanolignins. Herein, sulfated lignocellulose nanofibrils (SLCNFs) were obtained from the poplar alkaline peroxide mechanical pulp (APMP) using a deep eutectic solvent (DES) and a mechanical defibrillation strategy, and flower-like BiOBr/SLCNF composites with oxygen vacancies were prepared by in situ synthesis. Due to the well-preserved lignin structure, abundant oxygen-containing functional groups, and the interconnected three-dimensional mesh structure in SLCNFs, the composites exhibited flower-like morphology, good dispersion and excellent adsorption performance after the introduction of SLCNFs. EPR analysis showed that the introduction of SLCNFs increased the number of oxygen vacancies in BiOBr, which improved the visible light absorption and reduced the recombination of photogenerated carriers. In addition, the photocatalytic activity improved with interfacial interaction between BiOBr and SLCNFs promoting the separation of electrons and holes. Therefore, BiOBr/SLCNF can effectively remove RhB in the dynamic continuous process of adsorption enrichment and photocatalytic oxidation. Under visible light, 99% of RhB was degraded within 30 min and 88.5% of tetracycline hydrochloride (TCH) was degraded within 60 min. Importantly, the main active species which removed RhB by BiOBr/SLCNF were ˙O2− and h+, and the BiOBr/SLCNF composites still have good stability and recyclability after 5 times of repeated use. Overall, the BiOBr/SLCNF composite photocatalyst has great potential for the purification of organic wastewater. [ABSTRACT FROM AUTHOR]

Background. Oil palm trunk (OPT) with highly cellulose content is a valuable bioresource for bioethanol production. To produce ethanol from biomass, pretreatment is an essential step in the conversion of lignocellulosic biomass to fermentable sugars such as glucose and xylose. Several pretreatment methods have been developed to overcome biomass recalcitrance. In this study, the effects of different pretreatment methods such as alkali pretreatment, microwave-alkali, and alkaline peroxide combined with autoclave on the lignocellulosic biomass structure were investigated. Moreover, ethanol production from the treated biomass was performed by simultaneous saccharification and cofermentation (SSCF) under different temperatures, fermentation times, and cell ratios of Saccharomyces cerevisiae NCYC 479 and pentose-utilizing yeast, Pichia stipitis NCYC 1541. Results. Pretreatment resulted in a significant lignin removal up to 83.26% and cellulose released up to 80.74% in treated OPT by alkaline peroxide combined with autoclave method. Enzymatic hydrolysis of treated OPT resulted in an increase in fermentable sugar up to 93.22%. Optimization of SSCF by response surface method showed that the coculture could work together to produce maximum ethanol (1.89%) and fermentation efficiency (66.14%) under the optimized condition. Conclusion. Pretreatment by alkaline peroxide combined with autoclave method and SSCF process could be expected as a promising system for ethanol production from oil palm trunk and various lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Lignocellulosic materials are mainly consisted of lignin, cellulose, and hemicellulose. Lignin is recognized as the main obstacle for the enzymatic saccharification of cellulose towards the fermentable sugars' production. Hence, the removal of lignin from the lignocellulosic feedstock is beneficial for reducing the recalcitrance of lignocellulose for enzymatic attack. For this purpose, various different alkaline pretreatments were examined in order to study their effect on the enzymatic saccharification of wheat straw, as a typical lignocellulosic material. Results revealed that the alkaline pretreatments promoted delignification reactions. Regarding the removal of lignin, the most efficient pretreatments were alkaline treatment with hydrogen peroxide 10% and NaOH 2% autoclave with delignification efficiencies of 89.60% and 84.86% respectively. X-ray diffraction analysis was performed to enlighten the structural changes of raw and pretreated materials. The higher the delignification of the raw material, the higher the conversion of cellulose during enzymatic saccharification. In all cases after enzymatic saccharification, the cellulosic conversion was much higher (32–77%) than the untreated wheat straw (8.6%). After undergoing alkaline peroxide 10% pretreatment and cellulase treatment, 99% of the initial raw straw was eventually solubilized. Thus, wheat straw could be considered as an ideal material for the production of glucose with proper pretreatments and effective enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

The major challenge for natural fiber composites is their inherent poor adhesion between fiber and the matrix, high moisture absorption, and UV degradation. Lignin and hemicelluloses are the major composites of natural fiber which are responsible for UV degradation and moisture absorption, respectively. In this study, the lignocelluloses (oil palm empty fruit bunch) were treated with alkaline peroxide to separate lignin and hemicelluloses. Composites were produced with treated and untreated fibers using up to 45% fiber with polypropylene matrix using twin-screw extruder followed by injection molding. To improve the interfacial bonding, maleic anhydride grafted polypropylene (MAPP) was used as a coupling agent in the formulation. Properties of composites were evaluated using tensile testing, flexural testing, impact testing, SEM, and FTIR. The tensile, flexural, and impact properties were found to be improved with alkaline peroxide-treated fiber composites compared to untreated fiber composites. Addition of coupling agent (MAPP) also found to provide improved properties of composites. [ABSTRACT FROM AUTHOR]

Continuous production of ethanol from alkaline peroxide pretreated and enzymatically saccharified wheat straw hydrolysate by ethanologenic recombinant Escherichia coli strain FBR5 was investigated under various conditions at controlled pH 6.5 and 35°C. The strain FBR5 was chosen because of its ability to ferment both hexose and pentose sugars under semi-anaerobic conditions without using antibiotics. The average ethanol produced from the available sugars (21.9-47.8 g/L) ranged from 8.8 to 17.3 g/L (0.28-0.45 g/g available sugars, 0.31-0.48 g/g sugar consumed) with ethanol productivity of 0.27-0.78 g l h in a set of 14 continuous culture (CC) runs (16-105 days). During these CC runs, no loss of ethanol productivity was observed. This is the first report on the continuous production of ethanol by the recombinant bacterium from a lignocellulosic hydrolysate. [ABSTRACT FROM AUTHOR]

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Renewable energy sources have been recognized as a viable alternative to fossil fuels. Among them, lignocellulosic biomass has emerged as a promising option for producing valuable bio-products, especially employing residual or waste material due to its consistency, reliability, local availability, and carbon neutrality. However, its efficient utilization is limited by the recalcitrance of cell walls, mainly caused by two chemical compounds, hemicellulose and lignin, reducing the accessibility to cellulose. Consequently, the hemicellulose and/or lignin in the cell wall need to be removed or rearranged to increase the accessibility to cellulose through the pretreatment of lignocellulosic biomass. Among the different pretreatments, oxidative processes efficiently enhance the digestibility of cellulose in lignocellulosic biomass, breaking down the complex structure of lignocellulosic biomass and making it more accessible for subsequent enzymatic or microbial degradation. Moreover, oxidative processes improve the reaction kinetics, are versatile in treating a wide range of lignocellulosic feedstocks, and reduce the generation of waste products. Therefore, this review aims to provide a detailed overview of the properties and composition of lignocellulosic biomass, its potential, and a comprehensive analysis of oxidative pretreatments, their advancements and recently developed innovative technologies. Furthermore, the application and economic feasibility of utilizing lignocellulosic biomass and the key obstacles hindering its widespread adoption are highlighted in this review. [ABSTRACT FROM AUTHOR]

It is still a challenge to find an effective solvent system that can simultaneously dissolve the cellulose and lignin in biomass residues to fabricate lignocellulose hydrogels (LHs). Herein, corncob residues from furfural production were pretreated with alkaline peroxide to regulate the lignin content. The lignin/cellulose composites with various lignin content were then dissolved and regenerated by a green and facile ZnCl 2 /CaCl 2 solvent system. The inorganic salt solvents were served as linkers and flexible LHs were obtained. Substrate material containing 10.75% lignin shows the best compressive stress (76.71 kPa). Inspired by its superior ionic conductivity, the hydrogels were assembled into a solid-state electrolyte for a zinc-ion hybrid supercapacitor. This research develops a feasible, simple, and low-cost route for lignin-containing hydrogel preparation and offers insights into the high-value application of agro-industrial lignocellulosic wastes. • Lignocellulose hydrogels (LHs) were obtained via a green and low-cost method. • The diffusion mechanism of CRs in ZnCl 2 /CaCl 2 solvent system was discussed. • Lignin content influenced the network structure and properties of LHs. • Substrate material with 10.75% lignin was the most appropriate for LHs preparation. • LHs were good electrolytes for fabricating zinc-ion hybrid supercapacitor. [ABSTRACT FROM AUTHOR]

Rice husk was employed as a source for producing silica micro‐ and nanoparticles through its digestion by soil fauna. Although many physicochemical methods for producing nanostructures have been studied, the biological processes remain mostly unexplored. Alkaline hydrogen peroxide with continuous control of reaction pH allowed removal of lignin bonds while preserving most of the cell wall and the silica present in the rice husk. The accessibility of lignocellulose was achieved without removing appreciable amounts of lignin, so this agricultural byproduct can be employed as feeding material for microarthropods Folsomia candida (Collembola). When these microarthropods are placed on a substrate of treated rice husk, more than 85% of degraded material is obtained, as compared to the untreated rice husk substrate, while the silica particles obtained show a slight decrease in average size. [ABSTRACT FROM AUTHOR]

Background: Inhibitors that are released from lignocellulose biomass during its treatment represent one of the major bottlenecks hindering its massive utilization in the biotechnological production of chemicals. This study demonstrates that negative effect of inhibitors can be mitigated by proper feeding strategy. Both, crude undetoxified lignocellulose hydrolysate and complex medium supplemented with corresponding inhibitors were tested in acetone–butanol–ethanol (ABE) fermentation using Clostridium beijerinckii NRRL B-598 as the producer strain. Results: First, it was found that the sensitivity of C. beijerinckii to inhibitors varied with different growth stages, being the most significant during the early acidogenic phase and less pronounced during late acidogenesis and early solventogenesis. Thus, a fed-batch regime with three feeding schemes was tested for toxic hydrolysate (no growth in batch mode was observed). The best results were obtained when the feeding of an otherwise toxic hydrolysate was initiated close to the metabolic switch, resulting in stable and high ABE production. Complete utilization of glucose, and up to 88% of xylose, were obtained. The most abundant inhibitors present in the alkaline wheat straw hydrolysate were ferulic and coumaric acids; both phenolic acids were efficiently detoxified by the intrinsic metabolic activity of clostridia during the early stages of cultivation as well as during the feeding period, thus preventing their accumulation. Finally, the best feeding strategy was verified using a TYA culture medium supplemented with both inhibitors, resulting in 500% increase in butanol titer over control batch cultivation in which inhibitors were added prior to inoculation. Conclusion: Properly timed sequential feeding effectively prevented acid-crash and enabled utilization of otherwise toxic substrate. This study unequivocally demonstrates that an appropriate biotechnological process control strategy can fully eliminate the negative effects of lignocellulose-derived inhibitors. [ABSTRACT FROM AUTHOR]

The hydrolysis and biotransformation of lignocellulose, i.e., biorefinery, can provide human beings with biofuels, bio-based chemicals, and materials, and is an important technology to solve the fossil energy crisis and promote global sustainable development. Biorefinery involves steps such as pretreatment, saccharification, and fermentation, and researchers have developed a variety of biorefinery strategies to optimize the process and reduce process costs in recent years. Lignocellulosic hydrolysates are platforms that connect the saccharification process and downstream fermentation. The hydrolysate composition is closely related to biomass raw materials, the pretreatment process, and the choice of biorefining strategies, and provides not only nutrients but also possible inhibitors for downstream fermentation. In this review, we summarized the effects of each stage of lignocellulosic biorefinery on nutrients and possible inhibitors, analyzed the huge differences in nutrient retention and inhibitor generation among various biorefinery strategies, and emphasized that all steps in lignocellulose biorefinery need to be considered comprehensively to achieve maximum nutrient retention and optimal control of inhibitors at low cost, to provide a reference for the development of biomass energy and chemicals. [ABSTRACT FROM AUTHOR]

The conversion of lignocellulosic agricultural waste into biofuels and other economically valuable compounds can reduce dependence on fossil fuels, reduce harmful gas emissions, support the sustainability of natural resources, including water, and minimize the amount of waste in landfills, thus reducing environmental degradation. In this paper, the conversion of agricultural wastes into biomethane, biohydrogen, biodiesel, bioethanol, biobutanol, and bio-oil is reviewed, with special emphasis on primary and secondary agricultural residues as substrates. Some novel approaches are mentioned that offer opportunities to increase the efficiency of waste valorization, e.g., hybrid systems. In addition to physical, chemical, and biological pretreatment of waste, some combined methods to mitigate the negative effects of various recalcitrant compounds on waste processing (alkali-assisted thermal pretreatment, thermal hydrolysis pretreatment, and alkali pretreatment combined with bioaugmentation) are evaluated. In addition, the production of volatile fatty acids, polyhydroxyalkanoates, biochar, hydrochar, cellulosic nanomaterials, and selected platform chemicals from lignocellulosic waste is described. Finally, the potential uses of biofuels and other recovered products are discussed. [ABSTRACT FROM AUTHOR]

Lignocellulosic pretreatment is an important stage in biomass utilization, which usually requires high input. In this study, a low-cost method using combined ensiling and NaOH was developed for lignocellulosic pretreatment. Sweet sorghum bagasse (SSB) was ensiled for 21 days and then treated with diluted NaOH (0%, 1%, and 2%) for fermentation. The results showed that the application of Lactobacillus plantarum (L) reduced fermentation losses of the silages, mainly low water-soluble carbohydrate (WSC) and ammonia nitrogen loss. Meanwhile, the application of Lactobacillus plantarum and ensiling enzyme (LE) promoted lignocellulosic degradation, as evidenced by low neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (ADL), and hemicellulosic (HC) contents. The dominant bacterial genera were Lactobacillus, uncultured_bacterium_f_Enterobacteriaceae, and Pantoea after silage, which corresponded to the higher lactic acid and acetic contents and lower pH. The reducing sugar yields of SSB increased after combined pretreatment of silage and NaOH and were further enhanced by the 2% NaOH application, as evidenced by the high reducing sugar yield and microstructure damage, especially in the L-2% NaOH group and the LE-2% NaOH group, in which the reducing sugar yields were 87.99 and 94.45%, respectively, compared with those of the no additive control (CK)-0 NaOH group. Therefore, this study provides an effective method for SSB pretreatment to enhance biomass conservation. [ABSTRACT FROM AUTHOR]

The newly isolated extreme thermophile Thermoanaerobacter pentosaceus was used for ethanol production from alkaline-peroxide pretreated rapeseed straw (PRS). Both the liquid and solid fractions of PRS were used. T. pentosaceus was able to metabolize the typical process inhibitors present in lignocellulosic hydrolysate, namely 5-hydroxymethyl furfural (HMF) and furfural, up to concentrations of 1 and 0.5 g L−1, respectively. Above these levels, xylose consumption was inhibited up to 70% (at 3.4 g-furfural L−1) and 75% (at 3.4 g-HMF L−1). T. pentosaceus was able to grow and produce ethanol directly from the liquid fraction of PRS, without any dilution or need for additives. However, when the hydrolysate was used undiluted the ethanol yield was only 37% compared to yield of the control, in which pure sugars in synthetic medium were used. The decrease of ethanol yield was attributed to the high amounts of salts resulting from the alkaline-peroxide pretreatment. Finally, a two-stage ethanol production process from PRS using Saccharomyces cerevisiae (utilization of hexoses in the first step) and T. pentosaceus (utilization of pentoses in the second step) was developed. Results showed that the two strains together could achieve up to 85% of the theoretical ethanol yield based on the sugar composition of the rapeseed straw, which was 14% and 50% higher compared to the yield with the yeast or the bacteria alone, respectively. Biotechnol. Bioeng. 2013; 110: 1574-1582. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of different pretreatments methodologies of hydrogen peroxide, alkaline hydrolysis (calcium hydroxide or sodium hydroxide), alkaline peroxide oxidation (hydrogen peroxide/calcium hydroxide or hydrogen peroxide/sodium hydroxide), and dilute acid hydrolysis (10%(w/w) sulphuric acid) on corn cob biomass waste potential for biofuel and biocommodities utilization. The structure and elemental compositions of treated solid biomass waste fraction were characterised by different analytical techniques such as gravimetry, steremicroscopy, scanning electron microscopy, Light microscopy, Fourier transform infrared spectroscopy, and carbon, hydrogen, nitrogen, sulphur, and oxygen analyser. The solid fractions were also estimated based on cellulose enhancement, hemicellulose solubilization and lignin removal. The liquid fractions were evaluated with atomic absorption spectrophotometry for heavy metals presence and high performance liquid chromatograph (HPLC) for the monosaccharides. In all the pretreatments, the performance of alkaline peroxide oxidation (hydrogen peroxide/sodium hydroxide) was superior to all other methods evaluated with the highest lignin removal (about 78%(w/w)), cellulose was also enhanced (up to 59%(w/w)) from an initial 16%(w/w), and hemicellulose solubilized up to 79%(w/w). More of the sugars were solubilized in the acid pretreated hydrolyzate. The pretreatment methods considered in this study established the economic viability of the corn cob for biocommodities and biofuel production. [ABSTRACT FROM AUTHOR]

Volatile products from thermal decomposition of lignocellulosic biomass have been well characterized, but the solid- and liquid-phase reactions during the early stages of decomposition are largely unknown. Here the initial solid-phase biomass thermal deconstruction reactions were analyzed in situ and with high particle heating rates, delineating how these processes occur. A variety of instrumentation was used to quantify the extent and relative rates of deconstruction, demonstrating that biopolymers resist the thermally energetic conditions to differing degrees, even when ensconced in biomass cell walls. Hemicellulose and the more frangible lignin components decompose and volatilize more readily than cellulose, which temporarily enriches biomass with cellulose. These chemical changes manifest in larger cell wall structural and mechanical property transformations. In all, this investigation concludes that these solid-phase reactions strongly influence the production rates of volatile species and will require additional study before these processes can be modeled precisely to improve yields of desired product. [ABSTRACT FROM AUTHOR]

Global concerns over fossil fuel dependence drive biomass use for fuel and chemical production. The goal is to develop conversion methodologies that make bio-based products competitive with petroleum-based ones. This review examines recent advances in biomass conversion processes, including both thermochemical and biochemical techniques. The selection of the most suitable conversion technique depends on biomass availability and the end goal. Currently, the focus is on developing catalysts and optimizing process parameters to make conversion technologies more efficient. Although some technologies are already commercialized, methods to process lignocellulosic and marine biomasses are still under development. In addition, significant resources are being devoted to optimizing processes to extract basic chemicals from biomass, consolidating the biorefinery concept. This review illustrates the main developments in these directions. [ABSTRACT FROM AUTHOR]

Bio-based succinic acid production holds great promise for the process sustainability through the use of renewable resources such as lignocellulosic biomass and the use of microorganisms that can utilize CO2 in fermentation processes. A critical review of the latest findings on succinic acid production from lignocellulosic biomass was discussed, by highlighting all the key aspects of optimization processes at different levels of the process from pre-treatment to succinic acid production. Chemical-physical pretreatments seemed to be the most appropriate for the pretreatment of lignocellulosic biomass, but many strategies are still needed to solve the problem of variability in initial composition, the presence of post-treatment inhibitory compounds and the use of green solvent. In addition, the saccharization-fermentation process seemed to be the most suitable for the fermentative process of hydrolysates obtained from pretreatment to produce bio-based succinic acid. Certainly new studies and strategies are still needed to overcome the weaknesses of the whole process of succinic acid production from lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

This review paper examines acid and alkaline pretreatments on perennial grasses for second-generation (2G) bioethanol production, a relatively unexplored area in this field. It compares the efficiency of these pretreatments in producing fermentable sugar and bioethanol yield. This study finds that alkaline pretreatment is more effective than acidic pretreatment in removing lignin and increasing sugar yield, leading to higher ethanol yields. However, it is costlier and requires longer reaction times than acidic pretreatment, while acidic pretreatment often leads to the formation of inhibitory compounds at higher temperatures, which is undesirable. The economic and environmental impacts of lignocellulosic biomass (LCB) are also assessed. It is revealed that LCB has a lower carbon but higher water footprint and significant costs due to pretreatment compared to first-generation biofuels. This review further explores artificial intelligence (AI) and advanced technologies in optimizing bioethanol production and identified the gap in literature regarding their application to pretreatment of perennial grasses. This review concludes that although perennial grasses hold promise for 2G bioethanol, the high costs and environmental challenges associated with LCB necessitate further research. This research should focus on integrating AI to optimize the pretreatment of LCB, thereby improving efficiency and sustainability in 2G biofuel production. [ABSTRACT FROM AUTHOR]

This study presents a novel approach for biorefining oat husks into furfural, leveraging a unique pilot-scale setup. Unlike conventional furfural manufacturing processes, which often result in substantial cellulose degradation and environmental concerns associated with sulfuric acid usage, our method utilizes phosphoric acid as a catalyst to achieve high furfural yield while minimizing cellulose destruction. Drawing on our research conducted in a distinctive pilot-scale environment, we successfully developed and implemented a tailored biorefining process for oat husks. Through meticulous experimentation, we attained a remarkable furfural yield of 11.84% from oven-dried mass, accompanied by a 2.64% yield of acetic acid. Importantly, our approach significantly mitigated cellulose degradation, preserving 88.31% of the cellulose content in oat husks. Existing catalytic (H2SO4) furfural manufacturing processes often lead to substantial cellulose degradation (40–50%) in lignocellulosic leftover during the pretreatment stage. As a result of the research, it was also possible to reduce the destruction of cellulose in the lignocellulose leftover to 11.69% of the output (initial) cellulose of oat husks. This research underscores the feasibility and sustainability of utilizing oat husks as a valuable feedstock for furfural production, highlighting the potential of phosphoric acid as a catalyst in biorefining processes. By showcasing our unique pilot-scale methodology, this study contributes to advancing the field of environmentally friendly biorefining technologies. [ABSTRACT FROM AUTHOR]

In deconstructing lignocellulosic biomass, processing solvents directly and indirectly influence the process efficiency by reducing recalcitrance, fractionating target components, preserving/modifying biomass components, etc. Hydrotropic solvents have shown effective biomass fractionation performance due to their unique amphiphilic structure. In particular, these hydrotropes effectively separate lignin from the cellulose-rich fraction with minimum modification and maximum recovery, which aligns well with the biorefinery strategy by enhancing the recovered lignin quality and quantity. Hydrotropic solvent functions as a catalyst in biomass fractionation/degradation and also as a solvent via aggregation and clustering for the dissolution of target components such as lignin. Moreover, this solvent approach has great potential in eco-friendly manufacturing in plant biomass utilization because of aqueous processing. In this review, chemical structure, amphiphilicity, roles and mechanism of hydrotropic solvents are discussed along with their recent applications in plant biomass utilization. Current challenges in their industrial applications and perspectives on the direction of future research directions are presented. [ABSTRACT FROM AUTHOR]

Pure cellulose nanofibers (CNFs) rapidly degrade in soil, limiting their prospective applications in agriculture. We incorporated lignin into CNFs as an antimicrobial and crosslinking agent to control the biodegradation rate. CNFs with different lignin concentrations were prepared by mechanochemical treatment in the presence of choline chloride-urea deep eutectic solvent. These were characterized using conductometric titration, scanning electron microscopy, and FT-IR. The fibers were applied to soil to determine the effect of lignin on soil respiration and nanocellulose degradation, and were used as a substrate for radish and cress seed germination. Modifying the lignin content of the fibers successfully modulated the biodegradation rate in soil. Fibers containing 35% lignin degraded 5.7% in 14 days, while fibers with 20% lignin degraded 20.8% in 14 days. Nanofiber suspensions showed low chemical inhibition for the germination of radish and cress seeds but higher lignin contents reduced the imbibition rate as a seed coating. This study presents the first use of lignin to control the biodegradation rate of cellulose nanofibers in a one-pot, scalable and sustainable system, allowing the advancement of lignocellulose nanofibers for applications such as seed coatings, mulches, and controlled release fertilizers. [ABSTRACT FROM AUTHOR]

Alkaline hydrogen peroxide (AHP) pretreatment is a promising process for enhancing enzymatic digestibility of lignocellulosic biomass in biorefineries. In the present work, the effects of organic bases (NH4OH and tri-ethylamine) and co-solvents (ethanol, isopropanol, tert-butyl alcohol, water) on AHP pretreatment efficiency of rice straw were studied and compared to the typical aqueous reaction with NaOH. It was found that the glucose recovery from enzymatic hydrolysis of the biomass pretreated by AHP at 35 °C for 24 h using NH4OH in aqueous/tert-butyl alcohol (73.6%) was higher than that achieved using ethanol and isopropanol (31.6–48.6%) and water (71.2%) under the same experimental conditions. Increasing H2O2 concentration from 1 to 10% v/v in the aqueous/tert-butyl alcohol with NH4OH led to enhancing sugar yield to from 349 to 623 mg/g pretreated rice straw, equivalent to the highest glucose recovery of 83.0%. Formation of highly porous structures in pretreated rice straw by removals of hemicelluloses and lignin was revealed by Fourier transform infrared spectroscopy and scanning electron microscopy while the increased crystallinity index was shown by X-ray diffraction. This modified low-temperature AHP pretreatment using organic solvent system is advantageous on recyclability potential of the reagents and potent for further implementation in lignocellulosic biorefineries. [ABSTRACT FROM AUTHOR]

The pre-treatment step of lignocellulosic ethanol production is recognised as the most energy intensive part of the overall process. Key objectives are thus that pre-treatments should operate effectively at low to moderate temperatures and at high percentage solids, in order to minimise energy inputs. Chemical pre-treatment of BSG using alkaline reagents, at moderate process temperatures, was optimised in terms of sugar release following enzymatic saccharification of the pre-treated residues. An excess of Celluclast ® cellulase enzyme was used to compare various pre-treatments in terms of the % of theoretical sugars that could be liberated. Using alkaline peroxide (5% H 2 O 2 /NaOH at pH 11) up to 87% of the theoretical glucose yield (based on composition of the pre-treated residue) was attained following pre-treatment of BSG at 25% (w/v) solids loading for 5 h at 100 °C. Pre-treatment using 5% NaOH at 25% (w/v) solids loading for 12 h at 50 °C liberated 92% of theoretical glucose This pre-treatment remained effective with process times as short as 2 h (ca. 70% of theoretical glucose). For NaOH pre-treatments the extent of lignin removal from pre-treated residues broadly correlated with the efficacy of the pre-treatment in terms of final saccharification yields. However, for alkaline peroxide pre-treatments no such correlation was observed. Saccharified BSG was prepared following treatment with the optimised NaOH or alkaline peroxide pre-treatments and the resultant hydrolysates fermented with Saccharomyces cerevisiae . Fermentation performance was superior for the NaOH pre-treated samples relative to alkaline peroxide generated feedstocks with shorter lag phases and faster attenuation rates. Mean ethanol concentrations of ca. 17.3 g/L and 8.4 g/L were achieved for the NaOH and alkaline peroxide fermentations respectively which corresponded to 81% and 43% of theoretical ethanol yields. [ABSTRACT FROM AUTHOR]

Water Hyacynth (Eichhornia crassipes) is a fast growing aquatic plant that represents a serious problem of invasion, so its transformation into ethanol is proposed as a solution, taking into account the imminent scarcity of fossil fuels worldwide and the panorama of opportunity that is lived in the world due to the legislation on biofuels. For this, four different pretreatments were evaluated taking into account production of sugars and final ethanol yield to select the most promising. In this preliminary selection, the Water Hyacinth exhibited chemical type compositional characteristics that make it a promising raw material for ethanol production, obtaining yields of 17.15 g/l, 18.10 g/l, 17.73 g/l and 4,53 g/l with the pretreatments aqueous ammonia soaking, alkaline delignification, pretreatment with diluted acid and alkaline peroxide, respectively. Finally, the pretreatments with diluted acid and alkaline delignification were selected to be studied more deeply through the application of an experimental design, obtaining an ethanol yield (better design conditions). 190.35 l/ton dry biomass fed to the diluted acid pretreatment and 197.33 l/ton dry biomass fed to the alkaline delignification pretreatment, from the solid fraction. [ABSTRACT FROM AUTHOR]

Pre-treatment of biomass is a necessary step for delignification as well as an unavoidable step in the journey of biomass to biofuel. Apart from delignification, defragmentation and partial depolymerization of biomass are two other additional useful steps in the overall process of pre-treatment. Ultimately these three steps together make the downstream enzymatic hydrolysis process more effective in producing optimum total reducing sugar. Several different pre-treatment technologies are available to delignify various types of biomasses with each of them being unique concerning specific advantages and disadvantages, characteristics of its own. However, different pre-treatment methods, in combination, have been found beneficial with higher delignification efficiency in comparison to a single pre-treatment method, implemented on its own. Apart from physical pre-treatment procedures like milling, grinding, steam explosion, etc., pre-treatment methods can be divided, roughly, into three groups: biological pre-treatment, physical pre-treatment and chemical pre-treatment. Chemical pre-treatments always arrest significantly higher attention due to their effectiveness and minimum treatment time required. In this review, a thorough discussion of various chemical and biological pre-treatment technologies, along with their efficacy and effective outcomes, have been discussed in order to understand their impacts on bioenergy industries. [ABSTRACT FROM AUTHOR]

Currently, in the context of biorefinery and bioeconomy, lignocellulosic biomass is increasingly used to produce biofuels, biochemicals and other value-added products. Microwaves and ultrasound are emerging techniques that enable efficient and environmentally sustainable routes in the transformation of lignocellulosic biomass. This review presents some of the most important works published in the last few years on the application of microwaves and/or ultrasound in lignocellulosic materials pretreatment and can be used as a starting point for research into this theme. This review is divided into four parts. In Part I, the theoretical fundamentals of microwave and ultrasound treatments are reviewed. Dielectric constants for biomass, factors that influence pretreatment, are some of the subjects addressed. In Part II, the effects that these techniques have on lignocellulosic biomass (on the size and surface area of the particle; on the content of lignin, hemicellulose and cellulose; on the crystallinity index of cellulose; on the effect of solubilization of organic matter; on hydrolysis and reduction of sugars) are discussed. In Part III, emphasis is given to the contribution of microwaves and ultrasound in obtaining value-added products. In this context, several examples of liquefaction and extraction procedures are presented. Part IV describes examples of performing sonocatalysis on lignocellulosic biomass to obtain value-added products, such as furfural, whose production is significantly reduced by ultrasound treatment. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass (LB) is a promising source that has the potential to revolutionize the world of bioenergy, bioproducts, and nondigestible dietary components. As a substrate, LB has proven to be particularly attractive for the production of high-value cello-oligosaccharides (COS) and xylo-oligosaccharides (XOS), which offer diverse applications in the food, biopharmaceutical, and other industries, as well as potential health benefits, including prebiotic and antidiabetic effects. However, despite these promising developments, the manufacturing of these oligosaccharides remains a challenge due to slow reactions and low yields. Therefore, this review presents various pretreatment techniques to improve enzymatic hydrolysis, as well as the possibilities of employing a multi-step process and utilizing thermostable enzymes to enhance the production of COS and XOS from LB. Additionally, this review addressed the potential for by-product recovery during the XOS and COS production and the separation of β-glucosidase enzymes using the "separation–adsorption" method in high-temperature and continuous systems for COS production. [ABSTRACT FROM AUTHOR]