(599bn) Ionic Liquid Pretreatment of Lignocellulosic Biomass and Enzymatic Saccharification

Many pretreatment technologies have been developed to overcome the recalcitrance of woody biomass and subsequently to improve biomass digestibility. Recently, ionic liquids have attracted much attention as green solvent due to low vapor pressure, good chemical and thermal stability and non-flammability. Ionic liquids have been utilized in the dissolution of both softwood and hardwood, depolymerization of hemicelluloses, delignification and reduction of cellulose crystallinity.In this study, mixed softwoods were pretreated with an ionic liquid, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), under a wide range of temperatures and duration times and the bioconversion efficiencies to fermentable sugars were estimated in the enzymatic hydrolysis experiments. The surface morphology, structures and compositions of softwood were significantly changed after the ionic liquid pretreatment. It was observed that the cellulose I structure was significantly changed to amorphous structure and converted to cellulose II especially at high temperatures. The cellulose digestibility of ionic liquid pretreated softwoods remarkably increased and considerably improved at the pretreatment of 120 and 130 ^oC. The conversion of cellulose to glucose was higher than 90% and the maximum glucose yield was measured to be about 78%. Through the study, it was clearly shown that ionic liquid pretreatment is one of the effective methods to produce high fermentable sugars without lignin dissolution from lignocellulosic biomass.