Effect of Particle Size in Polyethyltene Glycol-Assisted [BMIM][Cl] Pretreatment of Sugarcane Bagasse

Abstract

The present study investigates the effects of particle size on chemical and structural features of polyethylene glycol (PEG)-assisted 1-butyl-3-methyl imidazolium chloride ([BMIM][Cl]) pretreatment of sugarcane bagasse (SCB) by response surface methodology approach (RSM). Three particle size ranges named fine, medium, and coarse separated by mesh numbers 70, 30, and 14 were considered for this study. Temperature, time, and PEG concentration in the ranges of 100–160 °C, 60–120 min, and 1–5%(w/w), respectively, were chosen as the influencing parameters of the RSM. Percentage of glucan, xylan, and acid insoluble lignin (AIL) in the pretreated samples was evaluated as the responses. The optimization of the pretreatment process was conducted for each particle size, consequently the enzymatic hydrolysis of the samples treated in the optimum points implemented to determine the particle size range yielding the highest SCB conversion. Crystallinity index and crystallite size of the pretreated SCB were measured as the structural characterization of the lignocellulosic biomass. Glucan content of the samples pretreated in the optimum conditions was 62.8, 66.63, and 60.6% for fine, medium, and coarse particles, respectively. The results of 24 h enzymatic conversion of the SCB samples pretreated in optimum conditions were as 66.63, 76.01, and 53.77%, for fine, medium, and coarse particles, respectively. This study revealed that particle size has a significant effect on the pretreatment process, and medium particles are mostly affected by different process parameters and have had the highest enzymatic conversion.