文献类型： 外文期刊

第一作者： Hou, Xintong

作者： Hou, Xintong;Li, Zaixing;Hou, Xintong;Yao, Zonglu;Zhao, Lixin;Luo, Juan;Shen, Ruixia

作者机构：

关键词： lignocellulose; deep eutectic solvent; interaction mechanism; pretreatment

期刊名称：CHINESE SCIENCE BULLETIN-CHINESE （ 影响因子：1.1； ）

ISSN： 0023-074X

年卷期： 2022 年 67 卷 23 期

页码：

收录情况： SCI

摘要： Deep eutectic solvent (DES) is a mixture of two or more compounds with low melting point, which shows good pretreatment performance for different types of lignocellulosic biomass. Due to its advantages over environmental protection, low cost, designation and strong biocompatibility, DES has been widely used in many other fields, such as graded treatment of biomass components, the extraction of Chinese traditional medicine and so on. DES pretreatment can destroy chemical bonds such as hydrogen bonds and ether bonds in lignocellulosic raw materials. break the complex structure of lignin-carbohydrate, and promote the dissolution or hydrolysis of lignin and hemicellulose components, thereby increasing the relative content of cellulose. As we all know, lignocellulosic biomass is mainly composed of cellulose. hemicellulose and lignin. The combination of lignin and hemicellulose forms a dense structure, which is difficult for the biodegradation process. Based on the mechanism of DES pretreatment, this study elaborated the different action processes of depolymerizing lignin and dissolving hemicellulose, and pointed out that there was only a slight dissolving effect on cellulose. The mechanism of DES degrading lignin was studied in depth_ and the process diagram of the reaction between choline chloride/lactic acid (1:3) and lignin was presented. And a schematic diagram of the formation of monomers after the hydrolysis of hemicellulose was drawn. In addition_ DES pretreatment has distinct advantages over other chemical pretreatment& including multiple recyclability and low cost. The cost of DES pretreatment is only 1/10 of the ionic liquid according to the estimation from market research. The main influencing factors of DES pretreatment technology were comprehensively analyzed, which included species and molar ratio, temperature. pH and viscosity. By adjusting the molar ratio of donors and acceptors of hydrogen bond, physicochemical properties such as polarity, acidity and hydrogen bond strength could be improved. An increase in temperature leads to a decrease in DES viscosity, and more high-value product can be obtained only when the temperature and viscosity are optimal. Moreover, the characteristics of DES with different pH are quite different, and should be selected according to the actual pretreatment requirements. The research progress of DES on woody and straw biomass pretreatment was systematically reviewed. It can be found that when softwood was pretreated by DES, the lignin removal rate could reach up to 61%, while the lignin removal rate could reach more than 90% when pretreating hardwood or straw with low lignin content. For example. the lignin removal rate of corncob after DES pretreatment is the highest of 93.1%. It is worth mentioning that the optimum temperature for pretreatment of straw biomass is lower than that of woody biomass. The optimal pretreatment temperature of woody biomass is 120-145 degrees C, while the optimal pretreatment temperature of straw biomass is about 120 degrees C. What's more, the addition of auxiliary means such as microwave and additives can make the effect of DES pretreatment more significant. For example, Choline chloride/glycerol/ferric chloride pretreatment of sage could remove 78.88% lignin, which was 22.6% higher than that without Lewis acid. In general, the research of DES in the field of lignocellulosic biomass pretreatment is still in the infancy. The structure-activity relationship and reaction mechanism of DES still need to be further studied. Future research suggestions are proposed in the interaction mechanism between DES and biomass, performance design of different types of DES, combination with auxiliary means and recycling, which provide ideas and references for the research and application of DES pretreatment of lignocellulosic biomass.

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