Enzymatic Hydrolysis Residue Research Articles

Adsorption of Cu(ii) ions in aqueous solution by aminated lignin from enzymatic hydrolysis residues

Aminated lignin (AL) has been prepared by a Mannich reaction for the removal of Cu(ii) ions from aqueous solution.

Structural Variation of Lignin and Lignin–Carbohydrate Complex in Eucalyptus grandis × E. urophylla during Its Growth Process

Milled wood lignin (MWL), lignin–carbohydrate complex-rich fraction (LCC-AcOH), celluloytic enzyme lignin (CEL), and enzymatic hydrolysis residue (EHR) were sequentially isolated from Eucalyptus grandis × E. urophylla under mild conditions, and the variations of lignin–carbohydrate complex (LCC) linkages and lignin structures during the eucalyptus growth were investigated. The 2D HSQC NMR analysis showed that β-O-4′ and β–β′ were the main linkages in lignin, while other substructures were present in much lower amounts. The amounts of β-O-4′ in the MWL and LCC-AcOH fractions showed an increased tendency and those in the CEL and EHR fractions had no obvious variation with the eucalyptus growth. The S/G ratios of the MWL, LCC-AcOH, and CEL fractions increased first and then decreased, whereas those of the EHR fractions decreased with the tree age. The amount of phenyl glycoside (PhGlc) in the LCC-AcOH fractions varied consistent with the S/G ratio. The variation of the amount of benzyl ether (BE) in the MWL ...

Physicochemical characterization of residue from the enzymatic hydrolysis of sugarcane bagasse in a cellulosic ethanol process at pilot scale

One of the major obstacles to use lignin as feedstock for value-added products at industrial scale is that its physicochemical characteristics can widely vary. Thus, it is necessary to know such characteristics before applying in the synthesis of products. In this study, we produce a lignocellulosic biomass in pilot scale composed of lignin (47%w/w) and cellulose fibers (40%w/w). This biomass was obtained from the enzymatic hydrolysis of sugarcane bagasse that was pretreated by a hydrothermal process (190°C/10min). After obtaining this residue, which is listed here as “Enzymatic Hydrolysis Residue Lignin” (EHRL), its physicochemical and thermal characterization was performed. A highly concentrated lignin from the LignoBoost process in Kraft pulp mill, lignin LignoBoost (LBL), was also evaluated in order to compare it with the EHRL. The C9-formulae of the lignin extracted from the EHRL is C9.0H11.2O4.3S0.08N0.17(OCH3)0.9(OHphenolic)0.7(OHaliphatic)0.6 and the C9-formulae of the LBL is C9.0H7.9O1.4S0.16N0.01(OCH3)1.1(OHphenolic)0.7(OHaliphatic)0.5. By the 2D Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC) technique, syringyl/guaiacyl ratios for the EHRL and the LBL are 1.8 and 4.8, respectively. Thus, the EHRL appears to be promising for phenolic composite, for instance, since it has lower methoxyl content. The EHRL showed larger range of fiber particle sizes (<4.05mm–0.4μm) than the LBL (0.4–1090μm).

Coproduction of Ethanol and Lignosulfonate From Moso Bamboo Residues by Fermentation and Sulfomethylation

A novel integrated process to coproduce bioethanol and lignosulfonate from bamboo residues was investigated. Explicitly, the fermentable sugars (glucose and xylose) were saccharified from the kraft pulped bamboo residues with 12 % effective alkaline charge, followed by a sequential fermentation strategy was applied to produce bio-ethanol from these fermentable sugars. The kraft lignin (KL) generated in pulping process and the enzymatic hydrolysis residues (EHR) were sulfomethylated to produce lignosulfonate. Results showed that 229.8 g of KL, 495.6 g of fermentable sugars (368.7 g glucose and 126.9 g xylose) and 103.6 g of EHR were generated from 1000 g bamboo residues after consequent processes of kraft pulping and enzymatic hydrolysis, respectively. Under optimal conditions of fermentation and sulfomethylation, 1000 g bamboo residues could produce 201.4 g of ethanol (158.7 g from glucose and 42.7 g from xylose) and 234.9 g of pure lignosulfonate (197.6 g from KL and 37.3 g from EHR) from 1000 g bamboo residues. This integrated process may potential be an economically profitable for the biorefinery of bamboo residues.

Pyrolysis characteristics and kinetics of lignin derived from enzymatic hydrolysis residue of bamboo pretreated with white-rot fungus.

BackgroundThe lignocellulose biorefinery based on the sugar platform usually focuses on polysaccharide bioconversion, while lignin is only burned for energy recovery. Pyrolysis can provide a novel route for the efficient utilization of residual lignin obtained from the enzymatic hydrolysis of lignocellulose. The pyrolysis characteristics of residual lignin are usually significantly affected by the pretreatment process because of structural alteration of lignin during pretreatment. In recent years, biological pretreatment using white-rot fungi has attracted extensive attention, but there are only few reports on thermal conversion of lignin derived from enzymatic hydrolysis residue (EHRL) of the bio-pretreated lignocellulose. Therefore, the study investigated the pyrolysis characteristics and kinetics of EHRL obtained from bamboo pretreated with Echinodontium taxodii in order to evaluate the potential of thermal conversion processes of EHRL.ResultsFourier transform infrared spectroscopy spectra showed that EHRL of bamboo treated with E. taxodii had the typical lignin structure, but aromatic skeletal carbon and side chain of lignin were partially altered by the fungus. Thermogravimetric analysis indicated that EHRL pyrolysis at different heating rates could be divided into two depolymerization stages and covered a wide temperature range from 500 to 900 K. The thermal decomposition reaction can be well described by two third-order reactions. The kinetics study indicated that the EHRL of bamboo treated with white-rot fungus had lower apparent activation energies, lower peak temperatures of pyrolysis reaction, and higher char residue than the EHRL of raw bamboo. Pyrolysis–gas chromatography–mass spectrometry (Py–GC/MS) was applied to characterize the fast pyrolysis products of EHRL at 600 ℃. The ratios of guaiacyl-type to syringyl-type derivatives yield (G/S) and guaiacyl-type to p-hydroxy-phenylpropane-type derivatives yield (G/H) for the treated sample were increased by 33.18 and 25.30 % in comparison with the raw bamboo, respectively.ConclusionsThe structural alterations of lignin during pretreatment can decrease the thermal stability of EHRL from the bio-treated bamboo and concentrate the guaiacyl-type derivatives in the fast pyrolysis products. Thus, the pyrolysis can be a promising route for effective utilization of the enzymatic hydrolysis residue from bio-pretreated lignocellulose.

Depolymerization of Cellulolytic Enzyme Lignin for the Production of Monomeric Phenols over Raney Ni and Acidic Zeolite Catalysts

In the present study, cellulolytic enzyme lignin, which was isolated from enzymatic hydrolysis residues of bamboo, could be efficiently depolymerized into oily products with a yield of over 60 wt % using a range of acidic zeolites and/or Raney Ni catalysts. The degraded products are mainly composed of phenolic monomers, which can be used as versatile chemicals or the precursor for biofuel production. The yields of monophenols were 12.9 wt % and no more than 5.0 wt % when catalyzed by Raney Ni or acidic zeolites, respectively. However, a yield of monophenols as high as 21.0–27.9% was obtained using a Raney Ni combination with acidic zeolite catalysts. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis revealed that the depolymerization level of the oily fraction catalyzed by a combination of catalysts was more complete in comparison to those catalyzed by an independent catalyst. The results indicated that the catalytic activity of a fully heterogeneous catalyst combinatio...

An integrated process to enhance ethanol production from steam-exploded corn stover

An integrated process of enzymatic hydrolysis and fermentation was investigated to enhance ethanol production from steam-exploded corn stover. The process included enzymatic hydrolysis at a low substrate loading, fermentation of concentrated supernatant and solid state fermentation of enzymatic hydrolysis residue. The results suggested that enzymatic hydrolysis at a low substrate loading caused a high hydrolysis efficiency; Fermentation of concentrated supernatant provided a high ethanol concentration of 92.33g/L, which helped to decrease the cost of subsequent ethanol distillation; Simultaneous saccharification and fermentation of enzymatic hydrolysis residue was carried out, in order to enhance ethanol production as much as possible.

Bioethanol production: An integrated process of low substrate loading hydrolysis-high sugars liquid fermentation and solid state fermentation of enzymatic hydrolysis residue

An integrated process of enzymatic hydrolysis and fermentation was investigated for high ethanol production. The combination of enzymatic hydrolysis at low substrate loading, liquid fermentation of high sugars concentration and solid state fermentation of enzymatic hydrolysis residue was beneficial for conversion of steam explosion pretreated corn stover to ethanol. The results suggested that low substrate loading hydrolysis caused a high enzymatic hydrolysis yield; the liquid fermentation of about 200g/L glucose by Saccharomyces cerevisiae provided a high ethanol concentration which could significantly decrease cost of the subsequent ethanol distillation. A solid state fermentation of enzymatic hydrolysis residue was combined, which was available to enhance ethanol production and cellulose-to-ethanol conversion. The results of solid state fermentation demonstrated that the solid state fermentation process accompanied by simultaneous saccharification and fermentation.

Liquefaction of lignin by polyethyleneglycol and glycerol

Enzymatic hydrolysis lignin (EHL), isolated from the enzymatic hydrolysis residues of the biomass, was liquefied using the mixed solvents of polyethyleneglycol (PEG) and glycerol at the temperature of 130-170°C with sulfuric acid as a catalyst. The influences of liquefaction parameters, such as the molecular weight of PEG, mass ratio of sulfuric acid to EHL, liquefaction temperature and time, and mass ratio of liquid (liquefying cosolvent) to solid (EHL) on the residue content and hydroxyl number were discussed. The FT-IR spectrum result showed that the liquefaction product of EHL was polyether polyol. The hydroxyl number of the liquefaction product was 80-120 mgKOH/g higher than that of PEG.

Converting MSW to ethanol

Municipal solid waste is an environmental threat worldwide; however, the organic fraction of municipal solid waste (OF-MSW) has a great potential for the generation of fuels and high-value products. In the current study, OF-MSW was utilized for the production of ethanol, hydrogen, as well as 2,3-butanediol, an octane booster, by using Enterobacter aerogenes. Furthermore, a promising alternative to non-biodegradable petrochemical-based polymers, polyhydroxyalkanoates (PHAs), was produced. The OF-MSW was first pretreated by an acetic acid catalyzed ethanol organosolv pretreatment at 120 and 160 °C followed by enzymatic hydrolysis of the residual solids. The residual unhydrolyzed solids resulting from enzymatic hydrolysis were further anaerobically digested for methane production. The enzymatic hydrolysis of the solids prepared at 120 °C for 60 min led to the production of hydrolysate with the highest glucose production yield of 498.5 g/kg dry untreated OF-MSW, which was fermented to 139.1 g 2,3-butanediol, 98.3 g ethanol, 28.6 g acetic acid, 71.4 L biohydrogen, and 40 g PHAs. Moreover, 23.1 L biomethane was produced through the anaerobic digestion of the enzymatic hydrolysis residue solids. Thus, appreciable amounts of energy (8236.9 kJ) and an eco-friendly bioplastic were produced by the valorization of carbon sources available in OF-MSW.