胆碱脂肪酸盐离子液体预处理水稻秸秆提高多糖酶解反应的研究

Improvement of Enzymatic Hydrolysis of Polysaccharides in Rice Straw by Cholinium Alkanoate Ionic Liquid Pretreatment

摘要:

木质纤维素预处理是生物精炼制备生物能源的关键步骤之一。近年来，离子液体预处理木质纤维素逐渐受到人们的关注。本研究通过中和反应合成了7种胆碱脂肪酸盐离子液体，并用于水稻秸秆预处理。在25 ℃下，这些离子液体的粘度介于74~488 cP。结果表明，经这些生物离子液体预处理后，水稻秸秆中的多糖酶解效率得到了显著提高。并且，离子液体的预处理效果依赖于阴离子链长。其中，[胆碱][丁酸盐]为最适水稻秸秆预处理溶剂。在90 ℃下经[胆碱][丁酸盐]离子液体预处理6 h后的水稻秸秆酶解后，葡萄糖和木糖收率分别达70.62%和41.47%。这类离子液体能选择性从水稻秸秆中除去大量木质素和部分木聚糖，而不会改变纤维素的晶体结构，从而显著提高后续酶解效率。

Abstract:

Pretreatment of lignocellulosic biomass is a key step in the production of biofuels by biorefinement. Recently, ionic liquid (IL) pretreatment of lignocellulosic biomass has attracted increasing interest. In this study, seven cholinium alkanoate ([Ch][Alk]) ILs were synthesized via a neutralization reaction, and were used for the pretreatment of rice straw. At 25 ℃, the viscosities of these ILs ranged from 74 to 488 cP. After the pretreatment of rice straw by these ILs, the efficiency of the enzymatic hydrolysis of polysaccharides in rice straw was improved significantly. In addition, the pretreatment performance of ILs depended on the chain length of the anion. Among the tested ILs, cholinium butyrate ([Ch][But]) proved to be the optimal solvent for the pretreatment of rice straw. Following the enzymatic hydrolysis of rice straw pretreated by [Ch][But] at 90 ℃ for 6 h, the yields of glucose and xylose reached 70.62% and 41.47%, respectively. This type of IL could selectively remove lignin and xylan from rice straw, while retaining the cellulose crystalline structure, which significantly improved the efficiency of the subsequent enzymatic hydrolysis.