稀酸蒸汽爆破玉米秸秆预水解液的脱毒及乙醇发酵

摘要

The pre-hydrolyzate obtained from the acid-catalysed steam-exploded corn stover ( ASC) after washing with water was used as the raw material. The contents of fermentable sugars, carbohydrate degradation products and main lignin degradation products in the ASC pre-hydrolyzate were analyzed. The ethanol fermentation performance of the ASC pre-hydrolyzate before and after detoxification by three kinds of detoxification methods was also investigated. The results indicated that the ASC pre-hydrolyzate contained fermentable sugars including xylose (49. 50 g/L) and few glucose (9. 80 g/L), which could be fermented to produce ethanol. However, it was not beneficial to ethanol fermentation because of the existed inhibitors. The sugar utilization ratio and ethanol yield were only 87. 96 % and 74. 63 %,respectively, after 60 h fermentation. The ethanol fermentation of the ASC pre-hydrolyzate was greatly improved after the ASC pre-hydrolyzate detoxified by ethyl acetate extraction, yeast adsorption and sodium sulfite treatment. The sugar utilization ratio and ethanol yield of the ASC pre-hydrolyzate after detoxification by ethyl acetate extraction were 95. 40 % and 90. 71%, respectively, after 36 h. The sugar utilization ratio and ethanol yield of the ASC pre-hydrolyzate after detoxification by yeast adsorption were 97. 83 % and 81. 98 %, respectively, after 48 h. The sugar utilization ratio and ethanol yield of the ASC pre-hydrolyzate after detoxification by sodium sulfite treatment were 95. 55 % and 84. 74 %, respectively, after 48 h. Although the detoxification effect of ethyl acetate extraction exhibited the best performance, yeast adsorption and sodium sulfite treatment were the most potential option from the point of industrial application perspective.%以水洗稀酸蒸汽爆破玉米秸秆( ASC)得到的预水解液为原料,分析了ASC预水解液中可发酵性糖、碳水化合物降解产物和主要木质素降解产物的含量,研究了ASC预水解液乙醇发酵性能、3种脱毒方法对预水解液进行脱毒及乙醇发酵性能。研究结果表明,ASC预水解液中可发酵糖类主要含有木糖(49.50 g/L)及少量葡萄糖(9.80 g/L),可用于发酵制备乙醇,但含有大量抑制物不利于乙醇发酵,发酵60 h时的糖利用率和乙醇得率分别仅有87.96%和74.63%。 ASC预水解液经过乙酸乙酯萃取、酵母吸附和亚硫酸钠处理3种方式脱毒后乙醇发酵性能均得到较大改善：经乙酸乙酯萃取脱毒后发酵36 h时的糖利用率和乙醇得率分别为95.40%和90.71%；经酵母吸附脱毒后发酵48 h时的糖利用率和乙醇得率分别为97.83%和81.98%；经亚硫酸钠处理脱毒后发酵48 h时的糖利用率和乙醇得率分别为95.55%和84.74%。虽然乙酸乙酯萃取脱毒效果最佳,但从工业应用前景来看,酵母吸附和亚硫酸钠处理是最佳选择。