Influence of Alkaline Hydrothermal Pretreatment of Rice Straw on Biomass Composition

Abstract

Rice straw utilization for the production of fuel and other chemicals via fermentation route needs several pretreatments due to its compact structure between lignin and cellulose in the plant cell walls. It inhibits the decomposition of biomass by microorganism. In this study, rice straw was hydrothermally treated at different temperatures (100–200 °C) with (0-7%) NaOH addition to improve decomposition of biomass. This work demonstrated that the content of the lignin and hemicelluloses fractions was reduced with the increase of the hydrothermal temperature and NaOH content. The results of this study pointed out that hydrothermal treatment with NaOH addition can increase rice straw organic degradation as indicated by increasing delignification, hemicellulose solubilization and lower crystallinity index of rice straw. More lignin, cellulose and hemicelluloses were solubilized at higher severity factor. Thermogravimetric analysis showed that the rate of thermal degradation began at lower temperature for pretreated rice straw comparing to the untreated rice straw.