Organosolv pretreatments of rice straw followed by microbial hydrolysis for efficient biofuel production

The aim of this study is to optimize Organosolv pretreatment parameters for efficient lignin removal and polysaccharide release using response surface methodology based on central composite design. Organosolv pretreatment conditions (60–100 °C, 10–50 min and 50–90% acid concentration) were tested for maximum cellulose release and lignin solubilization and minimum hemicellulose decomposition. The optimum Organosolv pretreatment condition was achieved at an acid concentration of 69.85%, pretreatment time 29.68 min and pretreatment temperature of 75.41 °C. At optimal condition, 73.17% of lignin and 46.62% hemicellulose were solubilized, and 74.09% of cellulose was released. The high R squared and adjusted R squared values of 0.9801 and 0.9622 for lignin removal, 0.9831 and 0.9695 for cellulose released and 0.9851 and 0.9717 for hemicellulose solubilization shows that the quadratic models are adequate and the experimental data adequately fitted to the design model. Moreover, all the process parameters: temperature, time and concentration have a significant impact on the responses (disruption or depolymerization of rice straw biomass) where time had a very strong effect on the rice straw components (cellulose, lignin, and hemicellulose). The study demonstrated that the potential of the combination of Organosolv pretreatment and Bacillus sp. BMP01 hydrolysis of rice straw for enhancing sugar and ethanol yields.