Optimizing xylose production from pinewood sawdust through dilute-phosphoric-acid hydrolysis by response surface methodology

Response surface methodology was used to optimize the xylose production from pinewood sawdust through dilute-phosphoric-acid hydrolysis. The effects of independent variables on xylose yield were investigated, including reaction temperature (75-175 degrees C), reaction time (0-7.2 h), solution-to-feed ratio (4-20 mL/g), and phosphoric-acid concentration (0-6.67 wt%). Results indicated that the individual factor H3PO4 concentration and the interacting factors including temperature x time, temperature x H3PO4 concentration, and solution-to-feed ratio x H3PO4 concentration were all significant factors. Long reaction time (>5.4 h) and high phosphoric-acid concentration (>5%) showed little effect. Xylose yield increased with increasing temperature up to 125 degrees C. Higher phosphoric-acid concentration and larger solution-to-feed ratio also increased xylose yield. The coefficient of determination, corresponding analysis of variance, and parity plot indicated that the fitted model was appropriate for the acid hydrolysis process. The maximum xylose production of 90.95% could be obtained with the reaction temperature of 106.7 degrees C, reaction time of 4.57 h, phosphoric-acid concentration 4.49 wt%, and solution to-feed ratio of 12.51 mL/g. (C) 2018 Elsevier Ltd. All rights reserved.