Tuesday, May 3, 2011
Aqueous ammonia was utilized to remove lignin from xylose-removed rice straw by dilute sulfuric acid pretreatment. The ammonia treatment process was optimized by using response surface methodology (RSM). Also, the process was analyzed using statistical method. Main factors were agitation speed, temperature, ammonia concentration, solid/liquid ratio and treatment time. After fundamental experiment, factors for RSM were determined to be temperature, ammonia concentration and treatment time. Statistical analysis shows that the experimental results were reliable, and optima of ammonia treatment process were found to be 61°C of temperature, 20 % of ammonia concentration and 19 h of treatment time. After all pretreatments, X-ray diffractometry analysis was performed to observe the changes before and after ammonia treatment, and saccharification was carried out. Crystallinity index from XRD analysis of co-pretreated (ammonia and dilute sulfuric acid) rice straw was found to be 60.45%, and it was similar to that of alpha-cellulose. Glucose conversion of the rice straw was 91% at 2 h. The initial reaction rate of co-pretreated rice straw was 2 folds higher than dilute acid-pretreated rice straw.