采用稀盐酸和硝酸水解玉米芯产木糖及其优化

Kinetic Studies and Optimization of Dilute Hydrochloric Acid and Nitric Acid Hydrolysis of Corncob for Xylose Production

采用稀HCl和HNO3在酸质量分数为1.0%、2.5%和4.0%,反应时间10、30、50、90和120min,温度90和150℃条件下,对玉米芯水解产木糖进行研究。通过动力学模型数据预测木糖浓度,并采用响应曲面优化各个温度下的水解条件。优化得到的最适宜水解条件为温度150℃,预处理时间10 min,酸质量分数为1.0%;对应HNO3得到的木糖浓度为56.77 g/L,产率96.31%;HCl木糖浓度为45.38 g/L,产率76.99%。动力学结果成功预测了反应条件下的木糖浓度。通过对比得出HNO3对玉米芯的水解效果要优于HCl。

Xylose production by hydrolysis of corncob with dilute hydrochloric acid and nitric acid were studied, in respect to temperature （90 - 150 ℃）, acid concentration （1.0%, 2.5% and 4.0% ） and reaction time（ 10 - 120 rain）. Kinetic parameters of mathematical model for predicting the concentrations of xylose were found. The central composite ＇design of response surface method was used to optimize the pretreatment conditions. The results showed that hydrolysis conditions for highest xylose production was 1.0% acid concentration for 10 rain at 150 ℃, corresponding to 96.31% （56.77 g/L） total xylan con- verted to xylose for nitric acid, 76.99% （45.38 g/L） for hydrochloric acid. The models could be suc- cessfully used to predict the concentrations of xylose under the experimental conditions. The results showed the hydrolysis effect of nitric acid was much better than that of hydrochloric acid.