The optimized CO(2)-added ammonia explosion pretreatment for bioethanol production from rice straw

A CO(2)-added ammonia explosion pretreatment was performed for bioethanol production from rice straw. The pretreatment conditions, such as ammonia concentration, CO(2) loading level, residence time, and temperature were optimized using response surface methodology. The response for optimization was defined as the glucose conversion rate. The optimized pretreatment conditions resulting in maximal glucose yield (93.6 %) were determined as 14.3 % of ammonia concentration, 2.2 MPa of CO(2) loading level, 165.1 °C of temperature, and 69.8 min of residence time. Scanning electron microscopy analysis showed that pretreatment of rice straw strongly increased the surface area and pore size, thus increasing enzymatic accessibility for enzymatic saccharification. Finally, an ethanol yield of 97 % was achieved via simultaneous saccharification and fermentation. Thus, the present study suggests that CO(2)-added ammonia pretreatment is an appropriate process for bioethanol production from rice straw. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00449-014-1165-x) contains supplementary material, which is available to authorized users.