盐酸-乙二醇-水介质高效预处理山核桃壳及其糖化工艺

为了提高木质纤维素的酶解效率,采用盐酸辅助乙二醇对山核桃壳进行预处理。通过油浴的处理方式优化得出的最佳预处理条件为:处理介质为盐酸-乙二醇-水(1.2%:88.8%:10%,质量分数)的混合物,预处理温度为130℃,预处理时间为30min。为了减小预处理的温度和时间,采用微波辐射的辅助预处理,最佳预处理条件为:微波辐射温度100℃,微波辐射时间5min,微波辐射功率200W。糖化预处理后的山核桃壳经水解72h后,其还原糖产率可达到88.6%(油浴)和74.2%(微波)。利用电镜(SEM)和红外光谱(FT-IR)分析油浴和微波预处理后的山核桃壳,可以发现山核桃壳紧密的结构遭到破坏,变成更加易于酶解的松散、多孔结构,增加了酶可及度,因此很大程度上提高了糖化率。可见,盐酸-乙二醇-水溶液高效预处理可以提高山核桃壳酶解糖化的效率。

Effective pretreatment of hickory shell with hydrochloric acid-ethylene glycol-water media and its saccharification

To improve the enzymatic saccharification of lignocellulosic biomass, ethylene glycol assisted with hydrochloric acid was used for pretreating hickory shell in this study. After the optimization in oil-bath system, the optimal pretreatment condition was obtained as following:the pretreatment media was hydrochloric acid-ethylene glycol-water (1.2%:88.8%:10%, mass ratio), pretreatment temperature 130℃, and pretreatment time 30min. In order to reduce the pretreatment temperature and time, microwave radiation was employed to assist the pretreatment with hydrochloric acid-ethylene glycol-water (1.2%:88.8%:10%, mass ratio) media, and the optimal pretreatment condition was achieved as following:microwave radiation temperature 100℃, microwave radiation time 5min, and microwave radiation power 200W. These results showed that the saccharification rate of pretreated hickory shell was higher than that of untreated one. After the pretreatment with oil-bath and microwave radiation, the reducing sugar yield from the enzymatic hydrolysis could reach 88.6% (oil bath) and 74.2% (microwave) after 72h. By using electron microscopy (SEM) and infrared spectroscopy (FT-IR) analysis, the structure of pretreated hickory shell was destroyed, the structure became loose, and porous were easier to be enzymatically hydrolyzed, which increased the enzyme accessibility, thereby greatly improving the saccharification rate. Therefore, the pretreatment with hydrochloric acid-ethylene glycol-water solution can improve the efficiency of the enzymatic saccharification of hickory shell.