离子液体预处理对能源草木质素脱除率及酶解效率的影响

Effect of ionic liquid pretreatment on the lignin removal and enzymatic hydrolysis of Miscanthus × giganteus

关键词:  离子液体  预处理  木质素  奇岗  酶水解

Key Words:Ionic liquid  pretreatment  lignin  Miscanthus × giganteus  enzymatic hydrolysis

摘要:本研究以能源草奇岗为原料,探讨了不同工艺条件下醇胺类离子液体对奇岗草木质素的脱除效率,并利用红外光谱、X-射线衍射和扫描电子显微镜分析了醇胺类离子液体处理后奇岗草的官能团、结晶度和微观形貌的变化,通过探寻低成本、高效率脱木质素工艺来提高后续奇岗草酶水解效率。结果表明,五种离子液体中乙醇胺醋酸([EOA][OAc])预处理对原料奇岗木质素脱除效果最佳,处理效果优于咪唑类离子液体；[EOA][OAc]预处理较适宜的条件为预处理温度140 oC、预处理时间5 h和固液比1:10,此条件下木质素脱除率可达76.67%；而且经过预处理后奇岗草再进行酶水解72h时,葡萄糖和木糖产率分别达到85.78%和76.47%,比未经过预处理奇岗草葡萄糖和木糖产率分别提高437%和1197%。经过[EOA][OAc]预处理的奇岗草纤维素含量增加,纤维结构疏松,纤维素晶型不变,结晶度降低,纤维素可及度提高,从而有利于生产生物乙醇,从而为低成本处理生物质提供了新途径。

Abstract:In this study, energy grass Miscanthus × giganteus (M×g) was selected as raw material, pretreated by the alcoholamine-based ionic liquids under different conditions for delignification, and the changes of functional groups, crystallinity and microstructure were analyzed by infrared spectrum, X-ray diffraction and scanning electron microscope (SEM). The objective of exploring the low cost and high efficiency delignification process was to improve the efficiency of M×g enzymatic hydrolysis. The results showed that ethanolamine acetate ([EOA][OAc]) pretreatment among the five ionic liquids was the best for the M×g lignin removal, and better than imidazoles. The optimal pretreatment conditions of [EOA][OAc] were 140 °C, 5 h and solid-liquid ratio of 1:10, under which the lignin removal could reach up to 76.67%. The pretreated M×g was hydrolyzed by enzyme for 72 h, and 85.78% and 76.47% of the yield of glucose and xylose in M×g was obtained respectively, increased 437% and 1197%, respectively, than the unpretreated M×g. After pretreated by [EOA][OAc], the cellulose content of M×g increased, the fiber structure was loose, the cellulose crystal shape unchanged, the crystallinity decreased, and the availability of cellulose was improved, which was benificial for bioethanol manufacture, thus provide a new approach for low-cost biomass treatment.