Effect of Combination of Liquid Hot Water System and Hydrogen Peroxide Pretreatment on Enzymatic Saccharification of Corn Cob

Abstract

Alkaline hydrogen peroxide pretreatment is an effectively enhance the increasing enzymatic digestibility of lignocellulosic biomass for conversion to fuels and chemicals in the biorefinery processes. In this study, effects of H 2 O 2 on monomeric sugar in the liquid fraction during hydrogen peroxide pretreatment and sugar after enzymatic hydrolysis from corncobs were studied under varying reaction conditions. The temperature (30-120 o C) and H 2 O 2 concentration (2.5-10%) efficiently promoted sugar yield in the piqued fraction and improved enzymatic hydrolysis of pretreated solids. The optimal condition for H 2 O 2 pretreatment of corncob (H 2 O 2 concentration of 5% using 60 o C for 2 h) increased hemicellulose solubilization into the aqueous phase, resulting into the maximized pentose yield of 61.88% (xylose + arabinose) in the aqueous phase. H 2 O 2 pretreatment under the optimal conditions at 60 o C for 2 h, leading to the enhance glucose yield from enzymatic hydrolysis of the pretreated biomass using 10 FPU/g CelluclastTM (85.66 %) and small amount of formation of inhibitory by-products. Combined with glucose in the aqueous phase, this resulted in the maxima 95.61% glucose recovery from the native corncob. This was related to changes in crystallinity and surface area of the pretreated biomass. Scanning electron microscopy (SEM) showed disruption of the intact biomass structure resulting increasing enzyme's accessibility to the cellulose microfibers which showed higher crystallinity index compared to the native biomass as shown by X-ray diffraction with a marked increase in surface area as revealed by BET measurement. The results provided efficiency of H2O2 pretreatment on increasing sugar recovery and an efficient approach for its processing in biorefinery industry.