研究了不同预处理方法对玉米秸秆发酵产氢气的影响和秸秆降解产氢的机理。实验分别采用酸解(AP)、酸解耦合固态酶解(AEP)、高温蒸煮(HP)和高温蒸煮耦合固态酶解(HEP)的玉米秸秆进行发酵产氢,分析预处理后秸秆累积产氢量与可溶性糖含量的关系。在此基础上,通过秸秆化学组成成分分析、傅里叶变换红外光谱(FT-IR)和X-射线衍射分析,探讨了秸秆降解的机理。结果表明,秸秆的累积产氢量与可溶性糖含量基本正相关,秸秆糖化效率是影响秸秆累积产氢量的主要因素。四种预处理方法主要作用于秸秆半纤维素和纤维素的无定型区,预处理过程皆在不同程度上提高了秸秆的结晶度,并在极大程度上提高了玉米秸秆的累积产氢量。其中AEP方法预处理秸秆效果最好,累积产氢量达到了226.1 m L·(g·TS)-1。
The effects of acid hydrolysis pretreatment of corn cob on saccharification efficiency and fermentation bio-hydrogen production were investigated by orthogonal test design.The hydrolysis pretreatment of corn cob with dilute sulfuric acid was essential for adequately converting substrate into soluble saccharides and bio-hydrogen.The experimental results showed that acid hydrolysis pretreatment of corn cob was found most effective at hydrolysis temperature of 115℃,sulfuric acid concentration of 1.0%,hydrolysis time of 1.5 h and solid-liquid mass ratio 1∶10,in which both maximum saccharification efficiency of 0.5433 g·(g TVS)-1 and bio-hydrogen yield of 85.8 ml H2·(g TVS)-1 were observed.In addition,the mechanisms of degrading corn cob by acid hydrolysis and hydrogen fermentation were also discussed by means of X-ray diffraction(XRD)analysis and crystallinity calculation.
以溶解度、脱酰胺度为考察指标,研究蛋白质谷氨酰胺酶对小麦蛋白进行酶解改性的工艺。通过单因素及正交试验,对蛋白质谷氨酰胺酶酶解谷朊蛋白进行了工艺条件的优化。探讨蛋白质谷氨酰胺酶与谷朊蛋白质量比、酶解温度、酶解时间和酶解p H 4个工艺参数对酶解谷朊蛋白溶解度及脱酰胺度的影响,确定了蛋白质谷氨酰胺酶解改性小麦蛋白的最佳工艺条件:谷氨酰胺酶与谷朊蛋白质量比0.05︰1,酶解温度45℃,酶解时间26 h,酶解p H 7.3。在此酶解工艺优化条件下,谷朊蛋白溶解度为82.36%,脱酰胺度为45.76%。
在批式试验中以牛粪堆肥为天然产氢菌源,分别以蔗糖和稀酸水解玉米秸秆为底物,通过厌氧发酵考察不同牛粪堆肥处理方式对发酵产氢性能的影响,并在此基础上构建了稀酸水解玉米秸秆两步发酵联产氢气-甲烷体系。当以蔗糖为底物时,牛粪堆肥处理方式对产氢影响不显著,产氢量均较高;当以稀酸水解玉米秸秆为底物时,室温浸泡处理的牛粪堆肥产氢效果最好,氢气最大产量达到213.8 m L/g TS。以稀酸水解玉米秸秆产氢发酵液为底物进行甲烷发酵,使秸秆的综合能量回收率达到41.2%,较单一发酵产氢时的能量回收率13.2%显著提高。
