Synergistic effect of ionic liquid and dilute sulphuric acid in the hydrolysis of microcrystalline cellulose

Abstract

Hydrolysis of microcrystalline cellulose (MCC) using dilute sulphuric acid in ionic liquid was studied in a batch reactor. Imidazolium based ionic liquid (1-butyl-3-methylimdazolium chloride, [BMIM] Cl) was synthesized by nucleophilic substitution reaction and characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). MCC was dissolved in [BMIM] Cl and subsequently hydrolyzed by catalytic amount of dilute sulphuric acid. The effect of [BMIM] Cl on the crystallinity index, chemical and thermal properties was studied using XRD, FTIR and TGA analysis by regenerating the dissolved MCC. The amount of total reducing sugar (TRS) produced by the dilute acid hydrolysis was determined by 3, 5-dinitrisalcylic acid (DNS) method using UV–Visible spectroscopy. It was observed that prior dissolution of MCC with [BMIM] Cl resulted with high yield of TRS (92%) compared with the direct mixing of MCC, [BMIM] Cl and sulphuric acid catalyst which result in lower yield of TRS (25%).