不同类型深度共熔溶剂预处理的甘蔗渣酶解效率差异

The Difference for Enzymatic Hydrolysis of Sugarcane Bagasse Pre-treated by Different Deep Eutectic Solvents

为了探索深度共熔溶剂(DES)预处理生物质的机制,本文分别设计了五种以氯化胆碱为氢键受体(HBA)和以苹果酸为氢键供体(HBD)的DESs来预处理甘蔗渣,分析HBD和HBA对甘蔗渣组分和酶解效率的影响。在氯化胆碱为HBA的DESs中,乳酸-氯化胆碱(LC)的预处理效果和酶解效率最好,所得甘蔗渣残渣的纤维素含量为72.92%,纤维素降解度为60.43%,葡萄糖收率为56.90%;而在苹果酸为HBD的DESs中,苹果酸-氯化胆碱的预处理效果最佳,木聚糖和木质素去除率均为最高,纤维素降解度为43.35%,葡萄糖收率为38.00%。研究结果证明DES的HBA和HBD的作用皆不可忽略,其分子间氢键作用强度与其对生物质的解构能力负相关。并发现甘蔗渣的木聚糖去除率与氢键受供体的p Ka值具有一定的相关性;纤维素降解度与木聚糖去除率正相关,而与木质素去除率无关。此外,在一定范围内,DES分子间的氢键作用强度、DES与甘蔗渣的氢键缔合作用与预处理温度和时间有相关性。本研究为用于生物质预处理的新型DES的设计提供了一定的理论参考。

In order to evaluate the influence of deep eutectic solvents(DESs)pretreatment on lignocellulosic biomass,five DESs with choline chloride(ChCl)as hydrogen bond acceptor(HBA)and five DESs with malic acid as hydrogen bond donor(HBD)were used to pretreat sugarcane bagasse.The effects of HBDs and HBAs on the components and enzymatic hydrolysis efficiency of biomass were studied.Among ChCl-based DESs,lactic acid-choline chloride(LC)showed the best enzymatic hydrolysis efficiency.The cellulose content in the residue was 72.92%.The glucose yield and cellulose digestibility after saccharification were 56.90%and 60.43%,respectively.Among malic acid-based DESs,malic acid-choline chloride was the best one with the highest xylan and lignin removal,resulting in 43.35%of cellulose digestibility and 38.00%of glucose yield.The results showed that both HBD and HBA played a non-ignorable role in biomass deconstruction,and the strength of intermolecular hydrogen bond in DESs was negatively correlated with their deconstruction ability.Besides,it was found that the xylan removal could be correlated to the pKa value of HBDs or HBAs,while the cellulose digestibility was positively related to xylan removal,instead of delignification.In addition,the intermolecular hydrogen bond strength of DESs and the hydrogen bonding interaction between DES and biomass have been proved to be related to the pretreatment temperature and time in a certain range.Results of this work will provide a theoretical basis for developing novel DESs for biomass pretreatment.