Optimization of Alkyl Imidazolium Chloride Pretreatment on Rice Straw Biomass Conversion

Abstract

Conversion of lignocellulosic biomass to value-added biochemicals and biofuels have gained importance nowadays as a method to reduce environmental problems and to increase economical profits of wastes. One of the main bottleneck of this process is the ineffective hydrolysis of biomass to small sugars due to recalcitrant structure of lignocellulosic biomass. To improve enzymatic hydrolysis, ionic liquid pretreatment on rice straw was optimized to determine the operational condition. Here, two types of ionic liquids, including 1-Butyl-3-methyl imidazolium chloride (BMIM-Cl) and 1-Ethyl-3-methy limidazolium chloride (EMIM-Cl), were challenged with different pretreatment conditions based on Response Surface Methodology (RSM) and their pretreatment efficiencies were comparatively monitored. The pretreatment models representing the effects of BMIM-Cl and EMIM-Cl pretreatment parameters on sugar yields were generated with high R2 value at 0.9720 and 0.9356, respectively, advocating the reliabilities of the models. Validation experiments were performed to determine the power of model prediction and results showed that there were only 6.3 and 4.86% error in the cases of BMIM-Cl and EMIM-Cl pretreatments, respectively. In this study, BMIM-Cl pretreatment had higher efficiency on improvement of rice straw saccharification compared to EMIM-Cl pretreatment for 35.39%. The results suggested the importance of optimization before selection of pretreatment condition to different types of lignocellulosic biomass.