Microcrystalline cellulose Avicel was subjected to an ionic liquid (IL) [BMIM]Cl pretreatment step to obtain a high conversion of soluble sugars in the enzymatic hydrolysis of cellulose. Avicel dissolved completely in [BMIM]Cl, followed by precipitating into deionized water to obtain the regenerated cellulose. The ionic liquid can be recycled for further use. The high performance liquid chromatography (HPLC) analysis results indicated that after 24h, the sugar released form IL-treated Avicel was 94. 65%, much higher than that of the original Avicel (48.57%). Structure, crystallinity and morphology of the IL-treated Avicel were also investigated as following: the hydrogen bonding, detected by FTIR, was decreased; the crystallinity, monitored by XRD, changed significantly from crystalline to amorphous pattern; the morphology, examined by SEM, demonstrated the orderly structure was destroyed remarkably with some pores and holes in the cellulose substrates. These changes of Avicel pretreated with [BMIM]Cl led to the enhancement of sugar conversion during cellulose enzymatic hydrolysis.

Key words: cellulose, ionic liquid, pretreatment, enzymatic hydrolysis