Pretreatment of wheat straw using basic ethanolamine-based deep eutectic solvents for improving enzymatic hydrolysis

Zhao, Zheng; Chen, Xiaochun; Ali, Muhammad; Abdeltawab, Ahmed A.; Yakout, Sobhy M.; Yu, Guangren

doi:10.1016/j.biortech.2018.05.016

Cited by 170 publications

(74 citation statements)

References 47 publications

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“…Following the pioneering work conducted on biopolymer solubility in DES, a significant amount of research in this field has helped to gain a good understanding of the impact of DES treatment conditions on lignin yield and purity . These works generally involve reaction temperatures of 80–150 °C, and reaction times of 0.5–24 h. Several research groups, including our own, have studied the impact of the identity of the HBD used in the DES.…”

Section: Introductionmentioning

confidence: 99%

Deep Eutectic Solvent Extraction of High‐Purity Lignin from a Corn Stover Hydrolysate

et al. 2020

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A lactic acid/chlorine chloride‐based deep eutectic solvent (DES) was used for the extraction of high‐purity lignin (up to 94.7 %) in high yield (up to 75 %) from the hydrolysis/fermentation residue corn stover hydrolysate (CSH), which was generated from a pilot‐plant‐scale biorefinery. A range of extraction conditions were investigated, which involved varying reaction temperature, time, and DES composition. The relationship between lignin yield, purity, and structural characteristics with DES treatment conditions was determined. The extraction of high‐purity lignin from hydrolysis/fermentation residues presents a promising approach for enhancing the economic feasibility of a lignocellulose biorefinery. It was also determined that DES extraction can produce lignin with a controlled range of molecular weight and functional group content.

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Section: Introductionmentioning

confidence: 99%

Deep Eutectic Solvent Extraction of High‐Purity Lignin from a Corn Stover Hydrolysate

et al. 2020

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“…This is due to the fact that DESs removed the lignin and hemicellulose that wrapped and exposed the cellulose. 33 The loose structure of pretreated WS is conducive to penetration and hydrolysis by enzymes, thus providing favorable conditions for the enzymatic treatment of cellulose in the later stage and significantly improves the enzyme digestion efficiency. Furthermore, the surface of obtained solid residues is not as smooth as expected because the residues after pretreatment by DES still contain some non-fiber components.…”

Section: Resultsmentioning

confidence: 99%

“…29−32 Each method possesses its respective advantages and disadvantage in terms of pretreatment cost, energy requirement, operational simplicity, reaction condition, and difficulty of industrial applications. 33 For example, the cellulose and xylan conversions of WS pretreated by steam explosion integrated with 2% (w/v) sodium hydroxide were 87.8 and 43.8%, respectively. However, these pretreatment methods usually require a high pretreatment temperature (198–200 °C) and pressure (1.03–13 bar), resulting in the total loss of xylan.…”

Section: Introductionmentioning

confidence: 99%

“…19,23 Although pretreatment of WS using ionic liquids (ILs) overcomes some of these disadvantages of traditional techniques in terms of equipment corrosion, high temperature, and pressure, their use in industrial applications was restricted by high synthesis cost and complicated synthesis process. 33 In recent years, deep eutectic solvents (DESs), generally formed by complexion of hydrogen-bond acceptors (HBAs) with hydrogen-bond donors (HBDs), 34−36 have emerged as potential solvents in lignocellulosic biomass pretreatment due to its high efficiency on the depolymerization of lignin, low cost, low viscosity, low vapor pressure, biocompatibility, and environmental friendliness, gaining great attention from academic and industrial fields. 37−43 Most of the reported studies on DESs for lignocellulosic biomass pretreatment focus on choline chloride (ChCl) as an HBA, mainly due to the fact that ChCl can be mixed with various HBDs, such as amino acid, p -toluenesulfonic acid, carboxylic acid, and alcohol, to prepare DESs with certain solubility to lignin.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Enzymatic Hydrolysis and Lignin Extraction of Wheat Straw by Triethylbenzyl Ammonium Chloride/Lactic Acid-Based Deep Eutectic Solvent Pretreatment

et al. 2019

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Efficient and feasible pretreatment of lignocellulosic biomass waste is an important prerequisite step to promote subsequent enzymatic hydrolysis and enhance the economics of biofuels production. This study focuses on the pretreatment of wheat straw (WS) with triethylbenzyl ammonium chloride/lactic acid (TEBAC/LA)-based deep eutectic solvents to enhance biomass fractionation and lignin extraction. Effects of pretreatment time, temperature, and TEBAC/LA molar ratio on pretreatment were evaluated systematically. Results suggested that 89.06 ± 1.05% of cellulose and 71.00 ± 1.03% of xylan were hydrolyzed with enzyme loadings of 35 FPU cellulase and 82 CBU β-glucosidase (per gram of dry biomass) after pretreatment by TEBAC/LA (1:9) at 373 K for 10 h. A total monosaccharide yield of 0.550 g/g WS (91.27% of the theoretical yield) was achieved with 79.73 ± 0.93% of lignin removal. Furthermore, the 1H–13C two-dimensional heteronuclear single quantum correlation (2D-HSQC) NMR spectroscopy showed that the regenerated lignin (75.69 ± 1.32% purity) was mainly composed of the syringyl units and the guaiacyl units. Overall, the results in this study provide an effective and facile pretreatment method for lignocellulosic biomass waste to enhance enzymatic hydrolysis saccharification.

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“…Nonetheless, trace of DES may still remain in the recovered- or regenerated- biomass after washings. Some researchers focused on the influence of the solvents residue on the DES mediated biomass treatment processes, especially for the biomass component or the activity of enzymes ( Lehmann et al, 2014 ; Zhao et al, 2018 ). However, only limited attention has been paid to the effect of the DESs pretreatment of the supporting materials on the performance of the immobilized enzyme or the residual DES on the catalytic property and structure of enzyme.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Thermostability of Papain by Immobilizing on Deep Eutectic Solvents-Treated Chitosan With Optimal Microporous Structure and Catalytic Microenvironment

Lin

Feng

et al. 2020

Front. Bioeng. Biotechnol.

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Deep eutectic solvents (DESs) have attracted an increasing attention in the fields of biocatalysis and biopolymer processing. In this study, papain immobilized on choline chloride- lactic acid (ChCl-Lac) DES-treated chitosan exhibited excellent thermostability as compared to the free enzyme. The properties of native or DES-treated chitosan and immobilized enzyme were characterized by FT-IR, SEM, surface area and pore property analysis. Like the common enzyme immobilization, papain immobilized on DES-treated chitosan resulted in a lower catalytic efficiency and a higher thermostability than the free enzyme due to the restricted diffusion. The results also revealed that DES could control the active group content, thus achieving the appropriate microporous structure of immobilized enzyme. Meanwhile, it could also help to construct the optimal microenvironment by hydrogen-bonding interaction between enzyme, chitosan, and residual DES, which are benefit for maintaining an active conformation and subsequently a high thermostability of papain. Moreover, it was found that trace DES (10 mM) significantly promoted the activity of free papain (145%). Deactivation thermodynamics study showed that the DES could enhance the thermostability of papain especially at high temperature (half-life of 7.4 vs. 3.5 h) because of the increased Gibbs free energy of denaturation. Secondary structure analysis by circular dichroism spectroscopy (CD) agreed well with the activity and thermostability data, further confirming the formation of rigid conformation induced by a specific amount of DES. This work provides a new way of enzyme immobilization synergistically intensified by solvents and supporting materials to achieve better microporous structure and catalytic microenvironment.

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Pretreatment of wheat straw using basic ethanolamine-based deep eutectic solvents for improving enzymatic hydrolysis

Cited by 170 publications

References 47 publications

Deep Eutectic Solvent Extraction of High‐Purity Lignin from a Corn Stover Hydrolysate

Deep Eutectic Solvent Extraction of High‐Purity Lignin from a Corn Stover Hydrolysate

Enhanced Enzymatic Hydrolysis and Lignin Extraction of Wheat Straw by Triethylbenzyl Ammonium Chloride/Lactic Acid-Based Deep Eutectic Solvent Pretreatment

Enhancing the Thermostability of Papain by Immobilizing on Deep Eutectic Solvents-Treated Chitosan With Optimal Microporous Structure and Catalytic Microenvironment

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