Efficient Hydrolysis of Polysaccharides in Bagasse by in Situ Synthesis of an Acidic Ionic Liquid after Pretreatment

A highly efficient hydrolytic method using an acidic ionic liquid is proposed: pretreatment of biomass with H2SO4; simple in situ synthesis of an acidic ionic liquid, 1-(1-butylsulfonic)-3-methylimidazolium hydrosulfate ([(HSO3)(4)C(4)C(1)im]HSO4), through addition of a zwitterion to the pretreated solution; and subsequent hydrolysis in the [(HSO3)(4)C(4)C(1)im]HSO4 solution at 100 degrees C under microwave heating. The high yields of glucose and xylose (around 80 and 100%, respectively) were attributed to the pretreatment by H2SO4 and the efficient catalytic activity of the [(HSO3)(4)C(4)C(1)im]HSO4. The high yields were comparable to the highest yields of acid hydrolysis at around 100 degrees C among previous literature, and the present method achieved more rapid hydrolysis. Decomposition of glucose and xylose was negligible because the reaction temperature was relatively mild. We also identified an electrodialysis method to separate [(HSO3)(4)C(4)C(1)im]HSO4 into H2SO4 and the zwitterion for reuse. Almost all of the H2SO4 (97%) was transferred to the concentrate compartment, and 99% of the zwitterion remained in the dilute compartment during electrodialysis.