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Sugarcane bagasse was pretreated by green liquor combined with ethanol (GL-Ethanol) and green liquor combined with H2O2 (GL-H2O2). After 72 h of enzymatic hydrolysis, the glucose yields of sugarcane bagasse pretreated with GL-Ethanol and GL-H2O2 were 97.7% and 41.7%, respectively. The reason that GL-Ethanol was more effective than GLH2O2 has not been elucidated clearly. In this study, the chemical composition of the sugarcane bagasse and chemical structure of the isolated lignins after these two pretreatment methods were characterized to investigate their correlation with the enzymatic hydrolysis of sugarcane bagasse. The removal of lignins with GL-Ethanol pretreatment was much higher than that of GL-H2O2. In addition, the decomposition of cellulose was lower in the case of GL-Ethanol than in that of GL-H2O2. According to Fourier transform infrared spectroscopy (FT-IR) and 1H-nuclear magnetic resonance (NMR) studies, the ester bonds (belonging to lignincarbohydrate complex) could be broken during GL-Ethanol treatment. It was also found that the molecular weight of lignins obtained from GLEthanol was lower than that of lignins from GL-H2O2. [ABSTRACT FROM AUTHOR]

A combination of steam explosion (SE) and chemical pretreatments, such as acid sulfite (AS), alkali (AL), and alkaline sulfite (ALS), were evaluated using bamboo. Low pressure steam explosion at 1.25 MPa for 4 min was first applied to the bamboo. Then, the pretreated bamboo was delignified using three chemical pretreatments. Enzymatic hydrolysis was also compared among the pretreated bamboo samples. It was found that SE-ALS could be a potential method for bamboo pretreatment, which led to the reduction of lignin from 25.15% to 1.74% at 165 °C for 2 h in 5% (w/v) Na2SO3 and 0.7% (w/v) NaOH; however, little cellulose was solubilized during ALS pretreatment. A maximum glucose yield of 99.35% was achieved during the enzymatic hydrolysis process when combined with the SE-ALS pretreatment. The SE-ALS method resulted in a lower degree of lignin condensation and increased delignification compared to the SE-AS method. In addition, the SE-ALS pretreatment protected carbohydrates from degradation better than the SE-AL methods. [ABSTRACT FROM AUTHOR]

As a lignocellulosic material, wastepaper is a potential material for ethanol production. However, little research on the enzymatic hydrolysis of wastepaper pulp has been conducted. In this study, the enzymatic hydrolysis of different waste pulp fractions (R80 represents greater than 80-mesh wastepaper pulp, R80-180 represents the range of 80- to 180-mesh wastepaper pulp, and R180 represents smaller than 180-mesh waste paper pulp) were carried out at 50 °C, pH 4.8, for 96 h, with a substrate concentration of 5% (w/v) and cellulase loading of 18 FPU/g cellulose. In terms of the specific surface area, fiber structure, and surface morphology, R80-180 had the highest affinity to cellulase and therefore the highest glucose yield of 80.33%. R180 had the lowest glucose yield (55.36%) because of its high ash content (21.36%), which reduced the adsorption of cellulase to cellulose. The enzymatic hydrolysis of R80 mixed with R80 or R80-180 was also studied. Results indicated that adding R80-180 increased the glucose yield of R80. The highest glucose yield (82.57%) was obtained when 15% R80-180 was mixed with R80. However, the glucose content decreased when R180 was mixed with R80 because of its high ash content. [ABSTRACT FROM AUTHOR]

Furfural residues (FRs) were pretreated with laccase or a laccasemediator (1-hydroxybenzotriazole, HBT) system to produce fermentable sugar for bioethanol production. Compared to laccase-only pretreatment, laccase-mediator pretreatment dissolved more lignin. Approximately 10.5% of the initially present lignin was removed when FRs were treated with a laccase loading of 100 U/g of dry substrate in 1% (w/w) HBT at 48 °C for 24 h in an acetate buffer (pH 4.8). The enzymatic saccharification process was carried out by a combined laccase or laccase-mediator pretreatment without washing of the treated solids. The results showed that active laccase had a negative effect on the rate and yield of enzymatic hydrolysis. Laccase-oxidized HBT seriously reduced glucose yield. However, non-oxidized HBT increased glucose yield when laccase was deactivated at 121 °C for 20 min prior to enzymatic hydrolysis. The highest glucose yield, 80.9%, was obtained from the substrate pretreated with 100 U/g of dry substrate laccase and 1% (w/w) HBT at 48 °C for 24 h in an acetate buffer (pH 4.8). Furthermore, the structures of FRs before and after laccase-mediator pretreatment were characterized by scanning electron microscopy (SEM) and Fourier Transform Infrared spectroscopy (FT-IR). [ABSTRACT FROM AUTHOR]

Acorn starch was used for ethanol production by separate hydrolysis and fermentation (SHF) in this study. The influence of tannins on hydrolysis and fermentation was investigated using ultrasonic-assisted extraction (UAE) to decrease the amount of tannin before SHF. The tannin was shown to have a negative role in hydrolysis and fermentation, and UAE can improve the two processes. The tannin content of acorn starch decreased from 6.19% to 1.91% with the UAE pretreatment time of 200 min. When the pretreatment time was 120 min, the glucose concentration increased from 78.08 to 98.76 g/L after 24 h of hydrolysis. The highest ethanol concentration was 42.22 g/L, which was obtained from the same pretreated acorn flour fermented for 12 h. However, the maximum ethanol yield was 88.06% of the theoretical yield, while pretreatment time was 80 min. Scanning electron microscope images indicated that protein was separated from the starch granules by UAE, as well as by the molecular weight of starch which decreased significantly based on the results from gel permeation chromatography (GPC) analysis. [ABSTRACT FROM AUTHOR]

A combination of steam explosion (SE) and alkaline peroxide (AP) used to pretreat bamboo was investigated. Steam explosion at 224 °C for 4 min was applied to bamboo, and the pretreated bamboo was delignified by alkaline peroxide. Enzymatic hydrolysis was compared in the pretreated samples. Steam pretreatment led to remarkable hemicellulose solubilization (63.2%). Lignin solubilization (93.1%) was achieved by alkaline peroxide treatment of steam-pretreated bamboo at 80 °C for 1 h in 0.88% (v/v) H2O2, whereas only 33.4% of lignin was solubilized when using raw bamboo. Pretreatment methods resulted in a low degree of polymerization and increased hydrolysis of cellulose. A maximum glucose yield of 90.5% was achieved with a combined steam explosion and alkaline peroxide pretreatment. The surface structure of treated bamboo and the adsorption of enzyme on the substrate were characterized by X-ray photoelectron spectroscopy. Delignification decreased enzyme adsorption and increased enzymatic conversion. SEM analyses indicated that SE-AP pretreatment disrupted lignin networks and exposed crystalline cellulose in bamboo more effectively than SE or AP pretreatment alone. [ABSTRACT FROM AUTHOR]