Sunday, May 3, 2009
3-14
Optimization of Dilute Acid Hydrolysis of Rapeseed Straw as a Pretreatment for Conversion to Ethanol
Tae Su Jeong1, Kyung Yoen Won1, Byung-Hwan Um2, and Kyeong Keun Oh1. (1) Applied Chemical Engineering, Dankook University, San-29, Anseo-dong, Cheonan, Choongnam, Korea, Cheonan, South Korea, (2) Chemical Engineering, Forest Bioproducts Researh Initiative, University of Maine, 5737 Jenness Hall, University of Maine, Orono, ME 04469
Increasing use of the world's oil reserves has prompted much research into finding alternative sources of fuels and valued chemicals. The most likely renewable resource is lignocellulosic biomass--i.e., plant materials such as agriculture and forestry wastes. Of agricultural wastes, rapeseed straw is discarded in the process of harvesting for biodiesel production. The government of South Korea has introduced blending mandates specifically for diesel and this policy results in more hectares planted with rapeseed and it is therefore expected to increase supply of straw for ethanol production. The limiting factor in using lignocellulosic biomass is hydrolyzing the raw material into fermentable sugars. In this work, the dilute-acid hydrolysis of rapeseed straw was optimized. 69.0% of hemicellulose and 53.6% of lignin dissolved from rapeseed straw into the hydrolyzate using 0.77% (w/v) H2SO4 for 18 min at 164°C. The composition of pretreated rapeseed straw analyzed is 59.13% (w/w) glucan, 10.3 % (w/w) xylan, presented as XMG and 26.38% (w/w) lignin with extractives. It could be found that 6.4% (w/w) of the xylose and 1.1% (w/w) of the glucose were dissolved as other decomposed materials. From the mass balance analysis, acid hydrolysis gave a higher recovery of hemicellulose in the hydrolyzate, preserving cellulose on pretreated rapeseed straw under the optimized pretreatment condition. In this study, we also investigated the ethanol yield of the pretreated rapeseed straw by the Simultaneous Saccharification and Fermentation (SSF) process and characterized effects of the optimized pretreatment condition using SEM and AFM imaging technologies.