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Rice straw is a relevant and potential feedstock for bioethanol production due to its abundance and availability around the globe. In this study, a fractional factorial design (FFD 25–1) was applied to simultaneously evaluate the influence of only alkaline and acid-alkaline pretreatment conditions in glucose release, considering the glucose release after 12 and 24 h of enzymatic hydrolysis as responses and predicting alternatives for the fractionation of rice straw components. Hydrolysis yields (HY) higher than 90% were achieved using low enzyme loads (8 FPU/g substrate) after only 24 h of hydrolysis under optimized pretreatment conditions. Simultaneous DOE optimization showed that the acid step is optional to achieve higher HY but can contribute to a more holistic use of the hemicellulose fraction. Also, it significantly increased the hydrolysis efficiency compared to untreated rice straw (HY = 18%). Enzymatic hydrolysis with a different type of enzymatic cocktail in the optimized conditions using higher solid contents resulted in high cellulose conversion (up to 85%), showing the robustness of the DOE optimization and its applicability as a starting point for optimizations using other types of enzymes. Chemical and morphological analyses were also carried out to understand the effect of the treatments, aiming to achieve pretreatment and hydrolysis processes more effective for lignocellulosic biorefineries. [ABSTRACT FROM AUTHOR]

Potassium permanganate (KMnO4) and potassium ferrate (K2FeO4) were used as modifiers to modify molecular sieves, and the modification periods were 35 days (KMnO4) and 27 days (K2FeO4), respectively. About 1 mol/L NaOH was used to pretreat the molecular sieves during the modification process of K2FeO4, and the modification period was further shortened to 22 days. After modification, modified molecular sieve (MMS) could effectively and continuously remove ammonium (NH4+) and manganese ions (Mn2+) from water. The adsorption kinetics showed that the adsorption of NH4+ and Mn2+ by MMS conformed to the quasi-secondary kinetic model adsorption kinetic model, and the adsorption process was mainly chemisorption. During the modification process, SEM, EDS, BET and XPS were used to investigate the structural characteristics of MMS. In the modification mechanism of molecular sieve, lattice oxygen (referred to as Oα), Mn (II), and Mn (III) accelerated the oxidation of Mn2+ to Mn4+ and promoted the rapid formation of active manganese oxide, which played a key role in shortening the modification period of MMS. This study contributes to a better understanding of the preparation and performance of MMS through a comprehensive analysis of the optimized molecular sieve modification process and the exploration of the accelerated formation mechanism of active manganese oxide. [ABSTRACT FROM AUTHOR]

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This study evaluated the kinetic modeling of arabinoxylan (AX) extraction from Brewers’ spent grain (BSG) by alkaline pretreatment at atmospheric pressure, considering severe (low concentration of NaOH and high temperature) and moderate (high concentration of NaOH and low temperatures) process conditions. The effects of NaOH concentration and temperature on yield extraction were studied over time, as well as the concentration of weak acids and phenolic compounds at the end of the pre-treatment. The AX yield extraction varied from 41.2 % (1 M, 90 °C) to 64.8 % (4 M, 40 °C) after 1 h and 16 h, respectively. Acetic acid ranging from 420 ppm to 1020 ppm was released, while ferulic acid was the phenolic compound produced at the highest concentration ranging from 78.3 ppm to 224.1 ppm. In addition, rates of chemical reactions were correlated mathematically from the experimental data with a good fit, and a sensitivity analysis was performed to understand the kinetic behavior. The first-order kinetic model demonstrates that increasing AX extraction requires both low temperatures (between 30 and 40 °C) and low NaOH concentration, but at the same time, this effect increases the time required (16 h) to obtain the maximum AX yield (64.8 %).

Microwave-Assisted Alkali (MAA) pretreatment of corncob biomass was optimized for maximum fermentable sugar yield using dilute sulfuric acid hydrolysis. A Central Composite Design (CCD) investigated the effects of microwave power (450–9000 W), NaOH concentration (1.5 to 4.5% wt./v), and irradiation time (10–20 min) on lignin removal. The optimal MAA pretreatment conditions were found to be 691.73 W, 3.4% NaOH, and 15.5 min, resulting in the selective removal of 73.36% lignin with high retention of cellulose (71.69%) and hemicellulose (22.14%). Characterization techniques (FTIR, SEM, XRD, TGA) confirmed substantial changes in surface morphology, functional groups, crystallinity, and thermal stability of the pretreated corncobs. Dilute sulfuric acid hydrolysis (0.5–2.5%, 110130 °C, 3060 min) of the optimized sample yielded a maximum reducing sugar output of 537.42 mg/g, achieved at 0.534% H2SO4, 122.3 °C, for 58 min. Optimizing Microwave-Assisted Alkali pretreatment process for corncobs could boost biofuel production efficiency, sustainably utilize agricultural waste, and advance a more sustainable energy landscape. [ABSTRACT FROM AUTHOR]

Xylan is the most abundant constituent of hemicellulose fraction of lignocellulosic biomass. Short xylooligosaccharides (XOS), obtained via xylan hydrolysis, have well-known prebiotic and antioxidant properties that are beneficial for human and animal health. In this study, two alternative pretreatment strategies (alkali and hydrothermal) and three different enzymes were applied for enzymatic XOS production from sugarcane bagasse. The enzymatic hydrolysis was performed with nine different combinations of recombinant endo-xylanases from GH11 and GH10 families and GH11 xylobiohydrolase. Hydrothermal pretreatment followed by optimized enzymatic hydrolysis yielded up to 96 ± 1 mg of XOS per gram of initial biomass, whereas enzymatic hydrolysis of alkali-pretreated sugarcane bagasse rendered around 47.6 ± 0.2 mg/g. For both alkali and hydrothermal routes, the maximum yields of short-length XOS were obtained using the GH10 xylanase alone. Furthermore, differences in XOS profiles obtained by controlled mixtures of the enzymes have been evaluated. For both routes, the best yields of short-length XOS were obtained using the GH10 xylanase alone, which is consistent with the notion that sugarcane xylan substitutions partially hinder GH11 xylanase activity. The results presented here show that a green and cost-effective hydrothermal pretreatment path for xylooligosaccharides production, rendered considerably better XOS yields. [ABSTRACT FROM AUTHOR]

Optimum energy recovery and economical use of lignocellulose feedstocks required an efficient breakdown of their recalcitrance characteristics. This study investigated the alkali pretreatment of underutilized Arachis hypogea shells' structural arrangement and methane yield. The NaOH pretreatment was carried out with 1%, 2%, 3%, and 4% (w/w), an exposure time of 45 min, 30 min, 15 min, and 10 min, respectively, at an autoclave temperature of 90 ℃. The functional groups and morphological structure of the pretreated and untreated Arachis hypogea shells were investigated with Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) and digested in anaerobic condition at mesophilic temperature. Structural analysis results showed that NaOH pretreatment reduced cellulose crystallinity and altered the functional groups. At the same time, SEM images depicted disruption of the recalcitrant arrangement of Arachis hypogea shells. The methane yield was 217.63 ml/gVSadded, 222.33 ml/gVSadded, 256.78 ml/gVSadded, 219.61 ml/gVSadded, and 151.23 ml/gVSadded. This result showed that NaOH pretreatment improved the methane yield of Arachis hypogea shells and can be replicated at a commercial scale, and other lignocellulose feedstocks with similar structural arrangements can be considered. [ABSTRACT FROM AUTHOR]

Cellulose-rich sugarcane trash (SCT) biomass, an important agricultural residue generated in large quantities every year, was used as a potential feedstock for cellulose extraction in micro and nano form. Initially, the cellulose microfibers were isolated from the SCT by a two-step chemical treatment process (alkali pretreatment with sodium hydroxide followed by hydrogen peroxide bleaching) at different operating parameters. The microfibers were then converted into the nanoscale by acid hydrolysis. The quantification of the raw and chemically treated SCT was carried out by the Van Soest method to learn their chemical composition. Different characterisation techniques such as Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM), and Transmission Electron Microscopy (TEM) were used for the analysis of surface functional groups, thermal stability, crystallinity index, surface morphology, and the internal structure of the raw as well as chemically treated SCT biomass respectively. The quantification results show the optimum process conditions for the alkali pretreatment as 5% (w/v) alkali (NaOH) concentration, 60 °C, and 12 h process time and for bleaching as 20% H2O2 concentration, 80 °C, and 8 h process time. This produces material having 86.15% cellulose content. This indicates the effective removal of hemicellulose and lignin. For the acid hydrolysis reaction for converting cellulose microfibers into nanocrystalline cellulose, the concentration of H2SO4 required was 40 wt.%, which is comparatively lower than that reported in the literature (~ 65 wt.%). The characterisation results highlight the progressive enrichment in the cellulosic groups, thermal stability, and crystallinity of the material with respect to the processing stages. There was a progressive enhancement in the crystallinity index of the sample observed with respect to the chemical treatment, with a maximum of up to 84.83% for the hydrolysed material. The XRD and TEM analysis confirms the presence of nanocrystalline cellulose (NCC) in the final hydrolysed sample. [ABSTRACT FROM AUTHOR]

In the present study, both acidic and alkaline hydrolysate of pineapple waste was utilised for the production of biohydrogen using locally isolated bacterial strains. The bacteria were isolated from different wastewater sources and were identified as Proteus mirabilis, Pseudomonas aeruginosa, Bacillus altitudinus, Bacillus subtilis, Paenibacillus alvei, and Lysinibacillus sphaericus. Experimental results showed that the highest biohydrogen yield of 836.33 ± 48.02 mL H2 was produced from alkaline hydrolysate with Bacillus altitudinis during the 96thhr of fermentation. Among the different bacterial strains, B. altitudinis showed higher H2 production. Comparatively alkaline hydrolysates exhibited a higher yield of hydrogen than acidic hydrolysates. The final pH of the experiment was found to be in acidic range. The total VFA concentration ranged between 930 ± 207.85 mg/L to 3050 ± 476.97 mg/L. Both sugar degradation and COD reduction were more than 80% in the acidic and alkaline hydrolysates while the lowest sugar degradation and COD reduction were observed for the untreated biomass. The rationale behind this study was to convert the waste biomass into energy by utilising the potential of native bacterial communities. [ABSTRACT FROM AUTHOR]

Straw pretreatment enhances the cellulose accessibility and increases the methane yield from anaerobic digestion. This study investigated the effects of alkali pretreatments with different chemical agents (NaOH, KOH, and Na2CO3) on the physicochemical and thermal characteristics of barley straw, as well as methane production from codigestion with sewage sludge. Artificial neural network modeling with a feedforward neural network (FFNN) and slime mold optimization (SMO) techniques were used to predict methane production. NaOH pretreatment was shown to be the best pretreatment for removing hemicellulose and lignin and for increasing the cellulose accessibility. Moreover, there was a 2.57-fold higher level of methane production compared to that from codigestion with untreated straw. The removal ratios for the total solids, volatile solids, and chemical oxygen demand reached 59.3, 67.2, and 73.4%, respectively. The modeling results showed that the FFNN-SMO method can be an effective tool for simulating the methane generation process, since training, validating, and testing produced very high correlation coefficients. The FFNN-SMO accurately predicted the amount of methane produced, with an R² of 0.998 and a 3.1x10-5 root mean square error (RMSE). [ABSTRACT FROM AUTHOR]

The uniqueness and relevance of the current work involve the production of bioethanol from the lignocellulosic biomass of two popular sweet sorghum varieties, viz., CSV19 and CSV24, using a yeast hybrid strain SP2-18, generated through genome shuffling. Bioethanol production from sweet sorghum bagasse varieties -CSV19 and CSV24 were examined utilizing three different alkali pretreatment techniques (PT1, PT2, and PT3). To determine the influence of the pretreatment procedure, a combination of alkali and hydrogen peroxide, with or without steam, was evaluated on the biomass of two promising varieties CSV19 and CSV24. To deconstruct the biomass, pretreatment procedures such as PT1 (2% NaOH, steam, and H2O2), PT2 (2% NaOH and H2O2), and PT3 (2% NaOH and steam) were used. The results revealed that bagasse processed with PT1 produced more bioethanol than the other two pretreatments, PT2 and PT3. Furthermore, Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were used to investigate the structural changes in biomass following pretreatment. The FTIR and SEM characterizations demonstrated that the microstructural changes of the pretreated sweet sorghum bagasse significantly differed from those of the untreated biomass. Enzymatic hydrolysis studies were also carried out on the pretreated sweet sorghum biomass (PT1, PT2, and PT3). Enzymatic hydrolysis yielded total reducing sugar concentrations of 58.62 g/L and 52.89 g/L in CSV19 and CSV24 sweet sorghum varieties respectively. Finally, we demonstrated that the resulting hydrolysate was used as a substrate and fermented with hybrid yeast strain SP2-18 derived from the parental strain Saccharomyces cerevisiae to convert the reducing sugars into bioethanol, a promising intermediate to biofuels and bioproducts. Genome shuffled yeast hybrid SP2-18 produced higher bioethanol productivity of 0.91 gL−1 h−1 and 0.85 gL−1 h−1 for CSV19 and CSV24 varieties of sweet sorghum respectively, as compared to parental strain S. cerevisiae which had bioethanol productivity of 0.56 gL−1 h−1 and 0.47 gL−1 h−1 respectively for sweet sorghum varieties of CSV19 and CSV24. [ABSTRACT FROM AUTHOR]

Straw pretreatment enhances the cellulose accessibility and increases the methane yield from anaerobic digestion. This study investigated the effects of alkali pretreatments with different chemical agents (NaOH, KOH, and Na2CO3) on the physicochemical and thermal characteristics of barley straw, as well as methane production from codigestion with sewage sludge. Artificial neural network modeling with a feedforward neural network (FFNN) and slime mold optimization (SMO) techniques were used to predict methane production. NaOH pretreatment was shown to be the best pretreatment for removing hemicellulose and lignin and for increasing the cellulose accessibility. Moreover, there was a 2.57-fold higher level of methane production compared to that from codigestion with untreated straw. The removal ratios for the total solids, volatile solids, and chemical oxygen demand reached 59.3, 67.2, and 73.4%, respectively. The modeling results showed that the FFNN-SMO method can be an effective tool for simulating the methane generation process, since training, validating, and testing produced very high correlation coefficients. The FFNN-SMO accurately predicted the amount of methane produced, with an R2 of 0.998 and a 3.1x10-5 root mean square error (RMSE).

Kitchen waste was mainly composed of carbohydrates, lipids, and proteins. Anaerobic digestion (AD) of kitchen waste usually occurred acidification and further deteriorated. In our previous study, alkali pretreatment combined with bentonite (AP/Be) treatment was proved to enhance high solid AD of kitchen waste. However, effects of AP time on AP/Be were not yet studied. This study investigated the effects of AP time on AP/Be treatment on enhancing high solid AD. The results showed that compared with the control group, the cumulative methane production rate could be increased by 3.30 times (149.7 mL CH4/g VS) and the volatile solids (VS) reduction rate increased by 63.36%. Microbial community analysis showed that the relative abundance of Methanosarcina and Methanosaeta were increased from 6.49 and 7.83% to 47.14 and 16.39% respectively. Predictive functional analysis showed that AP/Be treatment increased the abundance of energy production and conversion, coenzyme transport, and metabolism. This study revealed the potential mechanism of AP/Be enhanced kitchen waste AD performance and AP/Be was a potential strategy to strengthen AD. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) are biodegradable polymers that can be produced from lignocellulosic biomass by microorganisms. Cheap and readily available raw material, such as corn stover waste, has the potential to lessen the cost of PHA synthesis. In this research study, corn stover is pretreated with NaOH under conditions optimized for high cellulose and low lignin with central composite design (CCD) followed by characterization using Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). Design expert software performed further optimization of alkali pretreated corn stover for high total reducing sugar (TRS) enhancement using CCD using response surface methodology (RSM). The optimized condition by RSM produced a TRS yield of 707.19 mg/g. Fermentation using corn stover hydrolysate by Pseudomonas putida MTCC 2475 gave mcl-PHA detected through gaschromatography–tandemmassspectrometry (GC-MS/MS) and characterization of the PHA film by differential scanning calorimetry (DSC), FTIR, and nuclear magnetic resonance (NMR). Thus, this research paper focuses on using agriculture (stubble) waste as an alternative feedstock for PHA production.

A new biomass pretreatment method is mandatory to solve the existing issues, such as energy-intensive and expensive methods and the challenges of scaling up the biomass conversion processes. In this study, we pretreated the corncob biomass using the combined lime and hydrodynamic cavitation process and optimized the process conditions using the response surface methodology. The combined pretreatment process parameters in the hydrodynamic cavitation reactor included lime loading (0.05–0.15 g g–1), biomass loading (2.5–5%), and time (5–60 min). After optimization, maximum lignin reduction by 38.1% and cellulose increase by 22.6% were achieved at 0.1 g g–1 lime loading and 5% biomass loading after 60 min of pretreatment. Thus, the combined hydrodynamic cavitation reactor (HCR) and lime pretreatment is an efficient method for pretreatment of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Preparation of porous activated carbon (CK-Ar) through carbonization of extractive materials from alkali pretreated rice straw (RS) was developed as a precursor for the synthesis of sulfonated magnetic carbon (sMCK-Ar) to use as a solid acid catalyst. The physicochemical and morphological properties of CK-Ar, magnetic carbon (MCK-Ar), and sMCK-Ar samples were investigated with Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray, transmission electron microscopes, thermal gravimetric analysis, X-ray diffraction, and Brunauer–Emmet–Teller analysis. The acidic site density in sMCK-Ar was assessed using NH3-Temperature programmed desorption (NH3-TPH) method. Elemental CHNS analysis was used for the determination of the S density in the sulfonic samples. Also, vibrating-sample magnetometer analysis was used to determine the magnetic strength of sMCK-Ar. A porous soft structure with a surface area of 168.89 m2/g and different acidic functional groups with a density of 3.97 mmol/g was observed for the sMCK-Ar sample. The influence of temperature (130, 150, and 170 °C), time (1, 2, 3, and 4 h), and the ratio of catalyst to the substrate (C/S) (0, 0.25, 0.5, and 1 g/g) were investigated on the hydrolysis performance of microcrystalline cellulose (MCC). Pretreatment with phosphoric acid converted cellulose Ι to cellulose II. Using the sMCK-Ar as a catalyst for the hydrolysis of pretreated microcrystalline cellulose in water caused the maximum total reducing sugars yield of 68.50%. Optimum reaction conditions were obtained at a C/S ratio of 0.25 g/g and 3 h at 130 °C for the sMCK-Ar catalyst. [ABSTRACT FROM AUTHOR]

In this study, cotton/flax blended denim fabric was pretreated with NaOH to activate the surface hydroxyl groups of the cellulosic denim fabric to provide active sites for Ag+ ions resulting enhance silver nanoparticles (AgNPs) deposition onto the fabric surface. AgNPs were synthesized and deposited onto denim fabrics by in situ process, using tri-sodium citrate as both reducing and stabilizing agent. Particle size distribution, zeta-potential and X-ray diffraction measurement confirmed the formation of AgNPs, its stability in the colloidal dispersion and crystallinity, respectively. Fourier transform infrared spectroscopy revealed chemical interaction between the fabric and deposited AgNPs. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy analysis was used to study the treated fabric's morphology and surface characteristics, revealing the chemical state of AgNPs and AgNPs deposition on the fabric surface. Antibacterial activity of AgNPs finished denim fabric was assessed against both gram-positive and gram-negative bacterial strains, namely S. aureus and E. coli. The result showed significant inhibitory action of 90% against S. aureus and 85% against E. coli. After five and ten wash cycles, the treated fabric exhibited significant antibacterial activity, indicating low leaching rate of AgNPs from treated fabrics; however, repeated washing cycle reduces the antibacterial activity to some extent. The results of the tests on cell viability showed negligible cytotoxicity on human fibroblast cell lines. [ABSTRACT FROM AUTHOR]

There is a need for sustainable ways of processing plant fibers. Most chemical degumming methods pose a threat to the eco-system because of the presence of toxins during disposal. This study aimed to find sustainable ways of processing banana fiber with less harm to the environment. Sodium hydroxide (NaOH) and activated water were utilized for degumming and softening of the banana fiber. Activated water is an aqueous solution of electrolyte with strongly oxidizing active substances prepared by an electrochemical method. The alkali-pretreated banana fiber were immersed in activated water to refine banana fiber. The results from the study show that activated water further refined the fibers down to 39.7 µm diameter after NaOH pretreatment and also achieved better whiteness at 74.7%. The electrochemically activated water solutions displayed a promising effect in removing lignin, hemicellulose, and other impurities. The fibers of this quality could be used in the spinning of yarn and for other textile applications. Various analytical techniques, including digital microscope, scanning electron microscope, Fourier transform Infrared spectroscopy, X-ray diffractometry, tensile test, and whiteness test were utilized. These tests confirmed that the activated water used on banana fiber enhanced physical, chemical, and morphological properties.

Phragmites karka is one of the fast growing halophytes known to accumulate high biomass in a short span of time. In this study, we evaluated the potential of P. karka biomass from the Chilika Lagoon of India for the production of glucose which can possibly be converted into ethanol. Compositional analysis of biomass of P. karka was carried out and it was found that the biomass contained 33.12% cellulose, 28.17% hemicellulose and 24.81% lignin. For saccharification, the biomass were pretreated with two different pretreatments such as, cellulose solvent -and organic-solvent based lignocellulosic fractionation (COSLIF) and alkali (NaOH). Both of the pretreated biomass were digested with various dosages of cellulase and β-glucosidase enzymes. The enzymatic hydrolysis revealed that COSLIF using 85% phosphoric acid at a solid loading of 1 g biomass to 8 ml acid for 45 min at 50 °C exhibited the best result in terms of glucose release. Cellulase enzyme mixture containing 1 FPU cellulase and 10 IU β-glucosidase was found efficient in releasing 86.16% of glucose from the COSLIF pretreated biomass, whereas with the use of higher dosages of enzyme mixture (60 FPU cellulase and 60 IU β-glucosidase) alkali pretreated biomass could release only 72.65% glucose. The findings in this study addressed the potential use of P. karka as a source of biomass for the second generation ethanol production. [ABSTRACT FROM AUTHOR]

• Impact assessment of alkaline pretreatment on bioplastics methanization via BMP. • The methanization rate of tested bioplastics was improved by alkaline pretreatment. • Carbon solubilization due to pretreatment and methanization were material dependent. • PLA and the PLA/PCL blend were only mesophilically digested when pretreated. The effect of alkali-based pretreatment on the methanization of bioplastics was investigated. The tested bioplastics included PHB [poly(3-hydroxybutyrate)], PHBH [poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)], PHBV [poly(3-hydroxybutyrate-co-3-hydroxyvalerate], PLA (polylactic acid), and a PLA/PCL [poly(caprolactone)] 80/20 blend. Prior to methanization tests, the powdered polymers (500–1000 μm) at a concentration of 50 g/L were subjected to alkaline pretreatment using NaOH 1 M for PLA and PLA/PCL, and NaOH 2 M for PHB-based materials. Following 7 days of pretreatment, the amount of solubilized carbon for PLA and its blend accounted for 92–98% of the total initial carbon, while lower carbon recoveries were recorded for most PHB-based materials (80–93%), as revealed by dissolved total organic carbon analysis. The pretreated bioplastics were then tested for biogas production by means of mesophilic biochemical methane potential tests. Compared to unpretreated PHBs, methanization rates of pretreated PHBs were accelerated by a factor of 2.7 to 9.1 with comparable (430 NmL CH 4 /g material feed) or slightly lower (15% in the case of PHBH) methane yields, despite featuring a 1.4–2.3 times longer lag phases. Both materials, PLA and the PLA/PCL blend, were only extensively digested when pretreated, yielding about 360–380 NmL CH 4 per gram of material fed. Unpretreated PLA-based materials showed nearly zero methanization under the timeframe and experimental conditions tested. Overall, the results suggested that alkaline pretreatment can help to enhance the methanization kinetics of bioplastics. [ABSTRACT FROM AUTHOR]

Hydrothermal processing/liquefaction of biomass is the conversion of biomass in the presence of water at elevated temperature (> 200 °C) and autogenous pressure into functional chemicals and biofuels/hydrocarbons. The principal goal of the study is to understand the behavior of alkali-pretreated castor residue on product yield and conversion using hydrothermal liquefaction (HTL). The alkali pretreatment of castor residue was done using sodium hydroxide with variations in the pretreatment time. In this study, the hydrothermal liquefaction reaction was conducted at 260–300 °C for 60 min. The variation in alkali pretreatment time leads to change in the weight percentage of biomass components. The maximum yield of total bio-oil (TBO) observed at a temperature of 280 °C was 12.50 wt.%. The obtained products were analyzed using 1H NMR, FTIR, GC–MS, SEM, XRD, TOC, and elemental analysis. The formation of various chemical compounds was observed such as aldehydes, aromatics, phenolics, acids, and N- containing compounds. Phenolic compounds were found maximum in bio-oil and can be a useful feedstock in the chemical industry. The maximum heating value of bio-oil and biochar was 34.98 and 22.63 MJ/kg, respectively. [ABSTRACT FROM AUTHOR]

Immobilization of microbial cells for the production of industrially important enzymes has been reported to offer the advantages of recyclability, higher yields and cost effectiveness. The search for an appropriate matrix that is affordable and easy to prepare is a significant topic in microbial biotechnology. Here, an abundant type of agro-industrial waste—corncob—was utilized as an immobilization matrix for the production of xylanase from an indigenous yeast strain, Saccharomyces cerevisiae MK-157. This is the first report describing xylanase production from immobilized S. cerevisiae. To render the corncob matrix more porous, alkaline pretreatment was undertaken and yeast cells were immobilized on the matrix by cultivating at 30 °C for 48 h in Sabouraud dextrose broth. After incubation, the immobilized matrix was transferred to mineral salt medium containing 1% xylan and incubated at 30 °C for 24 h. Xylanase production was determined in cell-free culture supernatant and the matrix was recycled for up to seven cycles. Moreover, xylanase-mediated saccharification was carried out using sugarcane bagasse as a substrate and the release of reducing sugars was monitored. The results showed that the immobilized yeast produced 4.97 IU mL−1 xylanase in the first production cycle, indicating a >tenfold increase compared to the free cells. Xylanase production further increased to its maximum levels (9.23 IU mL−1) in the fourth production cycle. Nonetheless, the cells retained 100% productivity for up to seven cycles. The volumetric and specific productivity of xylanase were also the highest in the fourth cycle. Scanning electron microscopy images revealed the rough surface of the untreated corncob, which became more porous after alkaline pretreatment. Immobilized yeast cells were also visible on the corncob pieces. The saccharification of a natural resource—sugarcane bagasse—using xylanase preparation yielded 26 mg L−1 of reducing sugars. Therefore, it can be concluded that yeast strains can yield sufficient quantities of xylanase, allowing possible biotechnological applications. Moreover, corncob can serve as a cost-effective matrix for industrially important yeast strains. [ABSTRACT FROM AUTHOR]

Optimization of saccharification of rice straw plays a crucial role in harnessing maximum fermentable sugars through enzymatic hydrolysis of this complex polymer. The present study was aimed to evaluate the applicability of A. tubingensis NKBP-55 cellulolytic cocktail for generation of fermentable sugars and to carry out parametric optimization of the saccharification process followed by batch ethanolic fermentation of the rice straw hydrolysate. Also, evaluation of the alterations (composition, crystallinity and structural morphology) occurring in the wall polymer structure after sequential treatments was studied. The cellulolytic cocktail, under the statistically optimized conditions (rice straw 4% w/v and pH 5.0) liberated 578 mg fermentable sugars (glucose 463 mg, xylose 114.35 and cellobiose 0.71 mg) per gram of pretreated rice straw showing 2.17-fold enhancement. Candida shehatae NCIM 3501 utilized both glucose and xylose and produced 16.15 g/L bioethanol along with yield (YP/S) 0.50 after 24 h of fermentation. Its bioethanol production was observed to be better than Saccharomyces cerevisiae (13.39 g/L) and their co-culture (15.57 g/L). Sequential changes brought about by the enzymatic treatment of the solid substrate revealed by X-ray diffraction and FTIR analyses showed decrease in the absolute crystallinity (CrI) (54.80 to 48.31%) and total crystallinity index (TCI) (1.002 to 0.991) and confirmed the degradation of the crystalline domain of cellulose by enzyme. The study demonstrated the potential of cellulolytic cocktail produced by A. tubingensis NKBP-55 in rice straw saccharification and its efficient fermentation by conventional and xylose-fermenting yeast in batch ethanolic fermentation. [ABSTRACT FROM AUTHOR]

Jerusalem artichoke (Helianthus tuberosus L.) is emerging as one of the energy plants considered for biofuel production. Alkali and alkali-involved pretreatment methods have been widely used for the bioconversion of cellulosic materials due to their high sugar yield and low inhibitor release. However, the recovery and treatment of wastewater (black liquor) have been poorly studied. Here, we present a novel two-stage pretreatment process design for recycling black liquor. Jerusalem artichoke stalk (JAS) was first treated with 2% (w/v) NaOH, after which lignin was recovered by H2SO4 at pH 2.0 from the black liquor. The recycled solutions were subsequently used to treat the NaOH-pretreated JAS for the second time to dissolve hemicellulose. CO-pretreated JAS, hydrolysates, and acid-insoluble lignin were obtained after the above-mentioned two-stage pretreatment. A reducing sugar yield of 809.98 mg/g Co-pretreated JAS was achieved after 48 h at 5% substrate concentration using a cellulase dosage of 25 FPU/g substrate. In addition, hydrolysates containing xylose and acid-insoluble lignin were obtained as byproducts. The pretreatment strategy described here using alkali and acid combined with wastewater recycling provides an alternative approach for cellulosic biorefinery. [ABSTRACT FROM AUTHOR]

Fish bone gelatins were prepared from Anguilla rostrata by acidic or alkali pretreatment combined with hot water extraction. The physicochemical properties and gel properties of fish bone gelatins were investigated via the yield determination, gel strength measurement, SDS-PAGE analysis, ultraviolet full-wavelength scanning, infrared spectrum scanning, dynamic rheology measurement and scanning electron microscopy. As results, the yields of acid pretreated gelatin (AG60) and alkaline pretreated gelatin (BG60) were 13.6% and 6.88%, with the corresponding gel strengths of 101.95 g and 78.74 g, respectively. The hydroxyproline contents of AG60 and BG60 were 3.2 g/100 g and 2.7 g/100 g. Both gelatins were mainly consisted of β and α1, α2 chains, the contents of α1 and α2 chains in AG60 was significantly higher than those in BG60. Both AG60 and BG60 possessed the characteristic absorption peak of gelatin without any absorption peaks for other proteins. The AG60 possessed higher gelling temperature and melting temperature, as well as a shorter gelling time. Scanning electron microscopy analysis showed that AG60 showed a more dense and uniform gel network structure as compared with BG60. Present study suggested that the eel bone gelatin prepared by acidic pretreatment had better gel properties than that of gelatin prepared by alkali pretreatment.

Although extensin is a typical wall protein functional for plant cell wall construction and biomass production, its regulation on lignocellulose conversion into biofuels and bioproducts remains elusive. By collecting two extensin-overproduced rice straws (OsEXTLs), this study determined their cellulose levels significantly increased by 10 % along with soluble sugars and starch accumulation raised by 1–3.6 folds. After mild 0.5 % NaOH pretreatment, the OsEXTLs straws showed relatively enhanced biochemical conversion into total bioethanol production. Further under classic thermal-chemical conversion with the OsEXTLs enzyme-undigested lignocelluloses, this study generated the non-collapse biochar with more active chemical groups and the highest porosity, which caused mostly raised adsorption capacities with methylene blue (1162 mg/g) and Congo red (2714 mg/g) as a comparison with the previously-reported ones. Therefore, we proposed a mechanism model to illuminate how the extensin-enriched lignocellulose favors for higher-yield bioethanol conversion and better-performance biochar assembly, providing a novel strategy for desirable lignocellulose modification and effective biomass process. • Extensin-overproduced rice straw converts sugars and starch to high bioethanol yields. • Non-collapse biochar from enzyme-undigested lignocellulose maximizes dye adsorption. • Desirable biochar has high porosity and active chemical groups for enhanced adsorption. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of food waste is an encouraging technology for biogas production. Pretreatment of the substrate is needed to increase biodegradation. This study aimed to investigate the effect of alkali pretreatment and organic solvent pretreatment on biogas production. Physical pretreatment was also applied in this study. NaOH (0%, 2%, 4% and 6%) was used as alkali pretreatment. Ethanol (0, 2, 4 and 6%) was used as organic solvent pretreatment. The experiment was conducted in a 1 L batch digester under room temperature. Results showed that 0% NaOH generated the highest cumulative biogas yield of 46.1 mL/gVS. The best biodegradability of 37.5% was achieved in NaOH of 0%. The lower concentration of ethanol generated a higher biogas yield. The greatest cumulative yield of 41.5 mL/gVS was obtained at an ethanol concentration of 0% with a biodegradability of 33.84%. Statistical analysis proved that alkali pretreatment and organic solvent pretreatment had no significant effect on biogas production (p>0.05). Physical pretreatment had a significant effect (p<0.05) with the highest cumulative yield of 58.2 mL/gVS. The kinetic model proved that the modified Gompertz was a suitable model for predicting and simulating the kinetics of anaerobic digestion from food waste (R2 > 0.9). [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wood has gained popularity as a building and decorative material due to its environmentally friendly and sustainable characteristics. Yet, its long maturation time poses a limitation on meeting the growing demand for wood products. This challenge has led to the plantation of fast-growing wood as an alternative solution. Unfortunately, the poor mechanical properties of fast-growing wood hinder its application. In this study, we developed novel densification-modified wood by combining alkali chemical pretreatment, cyclic impregnation, and mechanical hot-pressing techniques. Additionally, the response surface method was employed to rapidly determine the optimal preparation parameters, reducing the cost of preparation under various conditions. The optimized parameters resulted in densification-modified wood with a flexural strength and modulus of elasticity of 337.04 MPa and 27.43 GPa, respectively. Furthermore, the densified wood achieved excellent dimensional stability by reducing the water-absorbing thickness swelling to 1.15 % for 72-h water soaking. The findings indicated that the densification-modified wood possessed high tensile strength and elastic modulus, along with excellent dimensional stability. The proposed densified wood modification technology in this study offers new perspectives and design guidance for the application of outdoor engineering structures, energy-efficient buildings, and decorative materials. [ABSTRACT FROM AUTHOR]

Abstract Crop straws represent enormous biomass resource convertible for biofuels and bioproducts, but lignocellulose recalcitrance restricts its saccharification for commercial utility. Despite genetic modification of lignin biosynthesis being attempted to reduce recalcitrance in bioenergy crops, it remains challenging to optimize lignin deposition without an unacceptable yield penalty. Based on gene expression analysis and phylogenetic tree profiling, a cinnamyl alcohol dehydrogenase gene (OsCAD2) as the target for genetic engineering of lignin biosynthesis in rice was selected in this study. Using CRISPR/Cas9 technology, independent homozygous transgenic lines with precise site mutation of OsCAD2, which showed slightly reduced lignin levels but markedly decreased p‐hydroxyphenyl (H) contents in lignin by 34% and increased guaiacyl (G) contents by 16%, compared to the wild type were generated in this study. Under mild alkali pretreatment (1% NaOH, 50°C), the OsCAD2 site‐modified lines showed effective lignin extraction up to 70% (of total lignin) from mature rice straws, which caused either significantly increased biomass porosity and cellulose accessibility or remarkably reduced cellulase adsorption to lignin in pretreated lignocellulose residues. These consequently led to almost complete biomass enzymatic saccharification with increased hexoses yields by 61%–72% in the modified lines, being much higher than those of the lignin‐altered lines reported in previous studies. Hence, this study has demonstrated a novel genetic engineering strategy to reduce lignocellulose recalcitrance with minimized biomass loss for cost‐effective biomass conversion to bioethanol in rice and bioenergy crops.

In this study, the effect of residual lignin and its structural modification of pretreated sugarcane bagasse (SCB) on enzymatic hydrolysis and fermentation was comprehensively evaluated by alkali and alkaline hydrogen peroxide (AHP) pretreatment. It was found that the AHP pretreatment had a negative influence on lignin dissolution compared with alkali pretreatment accompanied by a relatively low NaOH concentration (≤1%, w/v). However, there was less significance of enzymatic hydrolysis efficiency between NaOH and AHP pretreatment with >1% NaOH loading due to a high lignin removal above 78%. In addition, PEG 6000-assisted pretreatment was also performed to stabilize the enzymatic activity and further promote enzymatic digestibility and fermentability. The highest ethanol concentration of 59.96 g/L (61.22%) was obtained with PEG 6000-assisted 1% NaOH pretreated SCB at 30% solid loading. The structural features of the residual lignin indicated that most of the side chain structures were oxidized and that some aryl-ether bonds were dissociated after the pretreatments, especially in alkali pretreatment. The reduction of molecular weight and the breaking of lignin substructures help to achieve a more effective yield of enzymatic hydrolysis and fermentation. • High glucose yield was obtained from Alkali and AHP pretreatment on sugarcane bagasse. • Surfactants assisted pretreatment has potential to shorten reaction time and accelerate cellulosic ethanol production. • High ethanol concentration (59.96 g/L) was achieved to lower the distillation cost. • The reduced Mw values and broken lignin substructures achieve more glucose yield. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of the date palm empty fruit bunch is a promising technology for both solid waste management and biogas production. The date palm empty fruit bunch is a lignocellulosic waste that takes more time for degradation and has a low biodegradability, thus pretreatment is needed to improve anaerobic biodegradation. In this study, the substrate was pretreated with different ratios of alkali-NaOH: 6, 18 and 30% (w/w) (ratio weight of NaOH / weight of Volatile Solid) for 10 min at room temperature to evaluate the effect of high alkali concentration on the methane potential and biodegradability. The experiment was conducted in a 5 L batch reactor under mesophilic conditions (37 °C). The methane potential of the untreated substrate was 98.5 N mL/gVS. The best methane potential improvement of 104% was achieved in the treatment of 18% (w/w) (204 N mL/gVS) with a biodegradability of 50%. Besides, two kinetic models were used to fit the experimental methane potentials and to explore process parameters (Modified Gompertz and Transference function). The best fit for predicting the parameters of methane production was observed for the 18% (w/w) pretreatment using the transference function, with a maximum methane production rate of 5 N mL/gVS.d. [ABSTRACT FROM AUTHOR]

The goal of the research was to find out optimum hydrolysis parameters to convert corn stover to bioethanol using response surface methodology. The pretreatment of corn stover was administered using alkali potassium hydroxide. The results of the pretreated indicated that the important elements of corn stover were cellulose, hemicellulose, and lignin, 35.23, 23.5, and 16.3% respectively. Additionally, cellulose is the main component of cornstover that is sufficient for biofuel production. Experimental layout and statistical evaluation were carried out using the response surface technique. Acid concentration at (1.5-2.5%, w/w), particle dimension (0.15-0.25 mm), temperature (125-145 °C) and time (30-80 min) were used to evaluate the hydrolysis parameters. The result indicates that the optimum hydrolyzed parameters were, acid concentration; 2.334 (w/w %), particle size; 0.153 mm, temperature; 144.976 0C, and time; 77.233 minutes. The optimized independent variables were derived from the quadratic model and selected primarily based on the highest desirability. Under these conditions, the yield of glucose and xylose was 48.69 and 33.091% respectively. After 48 h of fermentation time, 27.1 g of ethyl alcohol concentration was investigated (this is equivalent to 92.07% of theoretical yield of ethyl alcohol at optimized conditions).

Abstract Background As a renewable carbon source, biomass energy not only helps in resolving the management problems of lignocellulosic wastes, but also helps to alleviate the global climate change by controlling environmental pollution raised by their generation on a large scale. However, the bottleneck problem of extensive production of biofuels lies in the filamentous crystal structure of cellulose and the embedded connection with lignin in biomass that leads to poor accessibility, weak degradation and digestion by microorganisms. Some pretreatment methods have shown significant improvement of methane yield and production rate, but the promotion mechanism has not been thoroughly studied. Revealing the temporal and spatial effects of pretreatment on lignocellulose will greatly help deepen our understanding of the optimization mechanism of pretreatment, and promote efficient utilization of lignocellulosic biomass. Here, we propose an approach for qualitative, quantitative, and location analysis of subcellular lignocellulosic changes induced by alkali treatment based on label-free Raman microspectroscopy combined with chemometrics. Results Firstly, the variations of rice straw induced by alkali treatment were characterized by the Raman spectra, and the Raman fingerprint characteristics for classification of rice straw were captured. Then, a label-free Raman chemical imaging strategy was executed to obtain subcellular distribution of the lignocellulose, in the strategy a serious interference of plant tissues’ fluorescence background was effectively removed. Finally, the effects of alkali pretreatment on the subcellular spatial distribution of lignocellulose in different types of cells were discovered. Conclusions The results demonstrated the mechanism of alkali treatment that promotes methane production in rice straw through anaerobic digestion by means of a systemic study of the evidence from the macroscopic measurement and Raman microscopic quantitative and localization two-angle views. Raman chemical imaging combined with chemometrics could nondestructively realize qualitative, quantitative, and location analysis of the lignocellulose of rice straw at a subcellular level in a label-free way, which was beneficial to optimize pretreatment for the improvement of biomass conversion efficiency and promote extensive utilization of biofuel.

This study investigated the effect of the anaerobic co-digestion of duck waste and alkali-pretreated groundnut shells at mesophilic temperature for methane yield optimization and waste management. Co-digestion of duck waste and alkali-pretreated groundnut shells was carried out using 100, 75: 25, 50: 50, 25: 75, and 100% duck waste: alkali-pretreated groundnut shells in a laboratory-batch digester at mesophilic temperature. The results indicated that anaerobic co-digestion of duck waste and alkali-pretreated groundnut shells is possible since no negative influence was observed during the joint digestion. It was observed that co-digestion released higher methane yield compared to mono-digestion. The optimum cumulative methane yield of 290 mL CH4 g/ VSadded was recorded from a 75: 25% ratio of duck waste: alkali-pretreated groundnut shells. This mixing ratio improved methane yield by 38%. This study confirms that the anaerobic co-digestion of duck waste and alkalipretreated groundnut shells can produce low-carbon fuel and economical waste management to maintain a sustainable environment.

This research aimed to demonstrate the feasibility of producing biobutanol by acetone-butanol-ethanol (ABE) fermentation on vine shoots at laboratory scale. In order to avoid a detoxification process prior to fermentation, an alkaline pretreatment and its posterior enzymatic hydrolysis were optimized through a response surface methodology (RSM) approach to minimize the concentration of phenolic inhibitors and maximize the amount of fermentable sugars. This vine shoots hydrolysate was directly fermented by 11 solventogenic Clostridium strains, reaching butanol concentrations over 8.0 g/L with C. beijerinckii CECT 508 and DSM 6423. The strain CECT 508 was selected to tune up a fermentation medium with the minimum possible amount of nutrients through a Plackett-Burman experimental design, thus reducing the cost of the fermentation broth while ensuring a high ABE solvent production. Finally, it was also shown that CaCO 3 could be substituted by eggshell powder as buffering agent, maintaining a biobutanol production over 7 g/L. This study demonstrates, for the first time, that biobutanol production from vine shoots is possible and that cost reduction based on alternative strategies of nutrient supplementation is viable. • A complete workflow to produce biobutanol from pruned vine shoots was developed. • An alkaline pretreatment allowed direct fermentation by 11 Clostridium spp. • A minimal nutrient fermentation broth permitted to reduce ABE fermentation cost. • Eggshell powder could substitute CaCO 3 in the ABE fermentation medium. [ABSTRACT FROM AUTHOR]

The pretreatment of wheat straw has been recognized to be an essential step prior to anaerobic digestion, owing to the high abundance of lignocellulosic materials. In order to choose economical and effective techniques for the disposal of wheat straw, effects of five pretreatment methods including acid, alkali, co-pretreatment of acid and alkali, CaO2, and liquid digestate of municipal sewage sludge on anaerobic digestion of wheat straw were investigated by analyzing biogas production and organic matter degradation in the study. The results showed that among these pretreatment methods, the methane yield was highest in the liquid digestate pretreated-wheat straw with 112.6 mL gTS−1, followed by the acid, alkali, and CaO2 pretreatments, and the lowest was observed in the co-pretreatment of acid and alkali. Illumina MiSeq sequencing of the microbial communities in the anaerobic digesters revealed that the genera Ruminiclostridium including Ruminiclostridium and Ruminiclostridium 1, Hydrogenispora, and Capriciproducens were the main hydrolytic bacteria, acidogenic bacteria, and acetogenic bacteria, respectively, in the anaerobic digesters. Capriciproducens and Hydrogenispora dominated in the first and the later stages, respectively, in the anaerobic digesters, which could work as indicators of the anaerobic co-digestion stage of sludge and wheat straw. The total solid and SO42−-S contents of the solid digestate and the NH4+-N concentration of the liquid digestate had a significant influence on the microbial community in the digesters. These findings indicated that liquid digestate pretreatment was a potential option to improve the anaerobic digestion of wheat straw, due to the low cost without additional chemical agents. [ABSTRACT FROM AUTHOR]

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Saccharification of widely available agro-industrial waste product, sugarcane bagasse (SB) can be achieved by microbial enzymes. Since single enzyme cannot completely saccharify SB, therefore, enzyme cocktails are designed for effective saccharification. In this study, alkali (NaOH) pretreated SB was saccharified using enzyme preparations from a halotolerant bacterium, Bacillus vallismortis MH 1 and a thermophilic bacterium, B. aestuarii UE25. The factors affecting the process of saccharification were statistically optimized by Central Composite design (CCD). After analysis, CCD predicted the optimum conditions i.e. 8.08 U of B. vallismortis MH 1 and 1.92 U of B. aestuarii UE25 for 1 g of substrate; temperature, 65℃; pH, 4; and reaction time, 48 h. Under optimal conditions, 501 mg g−1 reducing sugars were obtained after the saccharification of pretreated SB. The structural analysis of substrate by scanning electron microscopy, Fourier transform infrared spectroscopy and gravimetric analysis showed damaged structure, increased porosity and a reduction in cellulosic content, indicating significant degradation of the SB by the enzyme cocktail. Hence, it can be concluded that enzyme cocktail used in this study is effective for the saccharification of alkali pretreated SB.

The hydrogen production from hydrolysates of acid and alkali pretreated paddy straw using locally isolated facultative bacteria, Proteus mirabilis, was investigated. Acidic and alkaline pretreatments have increased the total sugar content in the hydrolysates, thus enhanced hydrogen production. Acidic hydrolysate produced higher yield of hydrogen than alkaline with a maximum cumulative hydrogen volume of 833.43 ± 21.72 mL H2, which was 3.33-fold higher than that of untreated substrate. The initial pH 6 was observed to be the optimum with 1.03 mol H2mol−1 glucose for the acidic hydrolysate. Similarly, the temperature 34 °C was found to be the most favourable with 1.00 mol H2mol−1 glucose for the acidic hydrolysate among the different experimental conditions studied. The present study confirms the clean energy production from waste biomass through dark fermentation by native bacteria and has potential scope for further studies. [ABSTRACT FROM AUTHOR]

The current work aimed to enhance the delignification of sugarcane bagasse (SCB) for bioethanol production. The optimization of alkali (sodium hydroxide) pretreatment parameters such as concentration and residence time was carried out by the Taguchi method using L16 orthogonal array with two factors and four levels. Sugarcane bagasse powder was mixed with sodium hydroxide (NaOH) solution (0.5-2 wt.%) and heated in an autoclave at 121°C and at varied times (30-120 min). From the statistical analysis of data, it was observed that delignification and glucan increased with the increased concentration and short time. The optimum parameters of NaOH pretreatment were 2 wt.% of NaOH concentration and 30 minutes of residence time. At the optimum conditions, 86.8% delignification and 46.6% glucan content of SCB were obtained. Thus, alkali pretreatment optimized by Taguchi design is the effective method to remove lignin and to increase cellulose or glucan content in sugarcane bagasse for facilitating the further catalytic hydrolysis in bioethanol production. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using reed (Phragmites australis (Cav.) Trin. ex Steud) as raw material, straw pulp was prepared by low alkali (less than 6%) pretreatment combined with mechanical grinding. The effects of pretreatment times and alkali dosages on pulp properties and pretreatment solution were investigated. The results demonstrated that alkali pretreatment affected FPI beating efficiency, and the beating energy consumption was lowest when pretreated with alkali dosage of 4%. With 5% NaOH pretreatment, the produced handsheets showed excellent properties that exceeded the requirements of food packaging paper and C-class corrugated paper. Moreover, low silicon content (=1.12 g/L) in the pretreatment liquor had an almost negligible effect relative to alkali recovery. Therefore, this study is important for researchers and industrial representatives seeking to use reed straw as material for pulping. [ABSTRACT FROM AUTHOR]

Crop straws represent enormous biomass resource convertible for biofuels and bioproducts, but lignocellulose recalcitrance restricts its saccharification for commercial utility. Despite genetic modification of lignin biosynthesis being attempted to reduce recalcitrance in bioenergy crops, it remains challenging to optimize lignin deposition without an unacceptable yield penalty. Based on gene expression analysis and phylogenetic tree profiling, a cinnamyl alcohol dehydrogenase gene (OsCAD2) as the target for genetic engineering of lignin biosynthesis in rice was selected in this study. Using CRISPR/Cas9 technology, independent homozygous transgenic lines with precise site mutation of OsCAD2, which showed slightly reduced lignin levels but markedly decreased p‐hydroxyphenyl (H) contents in lignin by 34% and increased guaiacyl (G) contents by 16%, compared to the wild type were generated in this study. Under mild alkali pretreatment (1% NaOH, 50°C), the OsCAD2 site‐modified lines showed effective lignin extraction up to 70% (of total lignin) from mature rice straws, which caused either significantly increased biomass porosity and cellulose accessibility or remarkably reduced cellulase adsorption to lignin in pretreated lignocellulose residues. These consequently led to almost complete biomass enzymatic saccharification with increased hexoses yields by 61%–72% in the modified lines, being much higher than those of the lignin‐altered lines reported in previous studies. Hence, this study has demonstrated a novel genetic engineering strategy to reduce lignocellulose recalcitrance with minimized biomass loss for cost‐effective biomass conversion to bioethanol in rice and bioenergy crops. [ABSTRACT FROM AUTHOR]

Crop straws provide large amounts of biomass resource for biofuels, but it remains to explore cost-effective lignocellulose process technology with additional valuable bioproducts. Using total eight rapeseed and corn stalks with distinct lignocellulose composition, this study initially performed mild alkali pretreatment (1% NaOH, 50 °C) for enzymatic hydrolysis and yeast fermentation to release bioethanol yields varied from 5 to 12% (% dry matter). By comparison, four corn stalks consistently showed more ethanol yields than those of the rapeseeds, but relatively higher sugar-ethanol conversion rates were examined in the rapeseed samples. Of all stalk samples, both genetic corn mutant (CY04) and classic rapeseed cultivar (Bn18) were respectively assessed as the desired lignocellulose residues for relatively high bioethanol production. Then, all remained solid residues of yeast fermentation were employed as biosorbents for Cd adsorption under various incubation conditions (pH, temperature, time, Cd concentration, biosorbent dose). In general, the solid residues exhibited much higher Cd adsorption capacities and removal rates than those of the raw stalks. In particular, two desirable rapeseed residues were of the highest Cd adsorption capacities, compared to the corn residues examined in this study or other major agricultural crop straws as previously reported. Furthermore, the solid residues were characterized as typical biosorbents via a classic chemical binding manner with much large surface areas accountable for their high Cd adsorption capacity. Therefore, this study has demonstrated a green-like strategy for low-cost cellulosic ethanol production and high-active biosorbents by selecting desired corn and rapeseed stalks. [ABSTRACT FROM AUTHOR]