| Abstract:In this study, Miscanthus × giganteus (M×g) was pretreated by alcoholamine-based ionic liquids under different conditions for delignification. The changes of functional groups, crystallinity and microstructure of M×g were analyzed by infrared spectrum, X-ray diffraction and scanning electron microscope. The results showed that ethanolamine acetate ([EOA][OAc]) among the five ionic liquids was the best for lignin removal of M×g. The [EOA][OAc] pretreatment result was better than imidazole-based ionic liquid pretreatment. The optimal conditions of [EOA][OAc] pretreatment were at 140℃ for 5 h with the solid-liquid ratio of 1∶10, in which the highest lignin removal of 76.67% was obtained. The yields of glucose and xylose of the pretreated M×g after using enzymatic hydrolysis mixed enzyme (20 FPU/g) in 50℃ for 72 h were 85.78% and 79.78%, respectively. The yields of glucose and xylose were 4.37 and 11.97 times of that of unpretreated M×g, respectively. Under the best conditions after the [EOA][OAc] pretreatment, the cellulose content of M×g increased from 37.99% to 52.49%, and the fiber structure was loose. The crystal structure of cellulose was unchanged, and the crystallinity decreased, as a result accessibility of cellulose was improved. When [EOA][OAc] was recycled and reused for the fifth time, the lignin removal rate was still (48.46±2.01)% indicating that [EOA][OAc] was suitable for recycling. |
