Pretreatment of rice straw for enhancing fermentable sugar yield using a high-pressure reactor

Rice straw has proved to be a potential renewable energy source due to its high polysaccharide contents and abundance availability. Fermentable sugars are easily obtained on hydrolysing rice straw using different pretreatment techniques. In this study, organosolv was used to pretreat rice straw in high-pressure autoclave reactor, under different conditions, for the removal of lignin and release of trapped polysaccharides. The composition of rice straw was analyzed as per National Renewable Energy Laboratory (NREL) guidelines. The temperature was varied as 120, 140 and 160 degree Centigrade and the exposure time was varied as 15, 30 and 60 minutes. The amount of sugar and lignin were greatly affected by temperature and time. It was found that sugar yield was maximum at 140 degree Centigrade and 15 minutes. At this pretreatment condition, it was observed that almost all of the hemicellulose was solubilized and 73% and of lignin was removed and 82% cellulose was released from the biomass. The removal of the high amount of lignin facilitates the release of the cellulose from the biomass matrix. Overall, this study showed the possibility of a high-pressure reactor for effective removal of lignin, which enhances the yield of fermentable sugars.