Synthesis of Green Deep Eutectic Solvents for Pretreatment Wheat Straw: Enhance the Solubility of Typical Lignocellulose

Zedong Teng, Liyan Wang, Bingqian Huang, Yue Yu, Jianwei Liu and Tinggang Li
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Zedong Teng: Innovation Academy for Green Manufacture, CAS Key Laboratory of Green Process and Engineering, Beijing Engineering Research Centre of Process Pollution Control, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
Liyan Wang: School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, China
Bingqian Huang: School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, China
Yue Yu: School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, China
Jianwei Liu: Beijing Engineering Research Center of Sustainable Urban Sewage System Construction and Risk Control, Key Laboratory of Urban Stormwater System and Water Environment, Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
Tinggang Li: Innovation Academy for Green Manufacture, CAS Key Laboratory of Green Process and Engineering, Beijing Engineering Research Centre of Process Pollution Control, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China

Sustainability, 2022, vol. 14, issue 2, 1-11

Abstract: Deep eutectic solvents (DESs), a novel and environmentally-friendly solvent, have high potential for biomass pretreatment due to its advantages of low cost, low toxicity, strong solubility, excellent selectivity and biocompatibility. Two types of DES (binary and ternary) were synthesized and characterized, and optimized ternary DES was selected to pretreat wheat straw for enhancement of the solubility of lignocellulose. Moreover, enzymatic hydrolysis was tested to verify the performance of pretreatment. In addition, the changes in surface morphology, structure and crystallinity of wheat straw pretreated by DES were analyzed to reveal the pretreatment mechanism. Experimental results indicated that viscosity exhibited little difference in different types of DESs, and a declining trend as the temperature increases in same DES. The ternary DES pretreatment efficiently enhanced the solubility of typical lignocellulose, with the optimal removal rate of lignin at approximately 69.46%. Furthermore, the total sugar concentration of the residue was about 5.1 times more than that of untreated wheat straw after the pretreated samples were hydrolyzed by the cellulase for 24 h, indicating that DES has the unique ability to selectively extract lignin and hemicellulose from wheat straw while retaining cellulose, and thus enhanced the solubility of lignocellulose. The scanning electron microscope (SEM) observation and X-ray diffraction (XRD) determination showed that the surface of wheat straw suffered from serious erosion and the crystallinity index of wheat straw increased after DES5 pretreatment. Therefore, DES cleaves the covalent bond between lignin and cellulose and hemicellulose, and reduces the intractability of lignin resulting in the lignin dissolution. It suggests that DES can be used as a promising and biocompatible pretreatment way for the cost-effective conversion of lignocellulose biomass into biofuels.

Keywords: deep eutectic solvents; pretreatment; lignocellulose; enzymatic hydrolysis; total sugar (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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