Pretreatment Optimization of Cholinium Ionic Liquid for Maximizing Sugar Release from Rice Straw

Abstract

In the biofuel production, an important step in biofuel production from lignocellulosic biomass is the transformation of cellulose into glucose by the function of cellulase. Pretreatment is a necessary process to promote the enzyme efficiency in hydrolysis. In this study, cholinium acetate ([Ch][OAc]), an ionic liquid (IL), was applied in pretreatment of rice straw. The [Ch][OAc] pretreatment conditions were optimized to maximize sugar release of rice straw using a response surface methodology (RSM) with three testing parameters, including loading mass ratio per IL, treatment time, and reaction temperature. The hydrolysis results demonstrated that the highest production of reducing sugars at 57.12 mg/0.1 g-rice straw was achieved at 130 °C for 304.27 min and using 13.79% loading mass ratio, which was 6.57 times higher than the untreated rice straw. Moreover, impacts of [Ch][OAc] pretreatment were analyzed using FTIR. The result showed that [Ch][OAc] removed crystallinity structure of cellulose and lignin content. These results suggested the potential of [Ch][OAc] pretreatment of biofuel production from lignocellulosic biomass.