Abstract
Ionic liquid (IL) and Ammonia Fiber Expansion (AFEX) pretreatments were studied to develop a comparative perspective for their effects on biomass structure, composition, and subsequent efficiency of enzymatic saccharification. It was found that AFEX pretreatment completely preserves plant carbohydrates, whereas IL pretreatment extracts 76% of hemicellulose. In contrast to AFEX, the native crystal structure of the recovered corn stover from the IL pretreatment process was significantly disrupted. Both pretreatment techniques can achieve more than 70% of the theoretical sugar yield in terms of glucose and xylose after 48 hours of enzymatic hydrolysis using commercial enzyme cocktails. IL pretreatment requires lesser enzyme loading and shorter hydrolysis time to reach 90% yields. Hemicellulase addition to the cellulase mixture led to significant improvements in the yields of both glucose and xylose for AFEX pretreated corn stover. These results provide insights into the mechanisms of IL pretreatment and indicate its promise as a novel pretreatment technique.