3-49: Rice Straw Oxidation Using Hypochlorite-Hydrogen Peroxide for Bioconversion to Ethanol

Rice straw is a lignocellulosic biomass that is a renewable organic substance and alternative source of energy. Presently, rice straw was pretreated in a novel manner using a hypochlorite-hydrogen peroxide (Ox-B) solution. The optimum pretreatment condition was analyzed by response surface methodology and the pretreated rice straw was hydrolyzed using exo-glucanase, endo-glucanase, hemicellulase, and β-glucosidase of Accellerase (endo-glucanase equivalent activity of 1,250 CMC U/g pretreated rice straw for 24 h). The optimum condition was 60 min pretreatment using Ox-B solution containing 20 ml NaClO and 100 ml hydrogen peroxide for 1 g rice straw in 220 ml total reaction volume, and 47.3 mg glucose and 72.5 mg xylose were obtained from 1 g rice straw. The structural change of rice straw after pretreatment and enzyme hydrolysis was examined by scanning electron microscopy. Following enzyme hydrolysis, Saccharomyces cerevisiae and Pichia stipitis were inoculated for ethanol production. Ox-B solution treatment was an essential step for efficient hemicellulose hydrolysis. With the initial 5% sugar concentration, the final ethanol concentration was about 1.67%, which is 87.3% of the stoichiometric and fermentation efficiency yield.