Optimization of BmimCl pretreatment of sugarcane bagasse through combining multiple responses to increase sugar production. An approach of the kinetic model

Sugarcane bagasse (SCB) was pretreated with 1-butyl-3-methylimidazolium chloride (BmimCl) at different conditions of temperature (80 °C to 150 °C) and solid loading (4 to 10%) at two times (20 and 60 min). The pretreatment conditions were optimized using a central composite rotatable design (CCRD) and desirability function having in mind the principles of green engineering. The pretreatments resulted in modifications of morphological and structural characteristics of biomass, also resulting in partial hemicellulose reduction. The founded optimal condition of pretreatment under the criterion of maximized sugar yield after enzymatic hydrolysis and minimized total sugar loss in pretreatment was 140 °C and 6% w/w of solid loading with 20 min of process. Also, a kinetic model was obtained verifying its validity with experimental values. It showed a lower activation energy of cellulose modification and hemicellulose conversion in comparison with the literature. One of the major findings was the strong correlation between glucose conversion and the degree of polymerization.