【目的】利用石墨化碳脱除竹材稀酸预处理液中的发酵抑制物，比较脱除前后的乙醇发酵收率，为高效快速的脱除发酵抑制物工艺提供参考。【方法】以毛竹粉为原料，经毛竹干质量2%的硫酸用量、固液比1∶6、180℃下保持60 min后得到预处理液，采用高效液相色谱仪测定预处理液中5种发酵抑制物的含量。利用装有石墨化碳的柱子常温下洗脱稀酸预处理液，以空气为洗脱剂，调节不同流速和洗脱次数，测定洗脱后预处理液中发酵抑制物的含量，计算石墨化碳的脱毒效果。利用稀酸和乙醇常温下冲洗脱毒后的石墨化碳柱，测定冲洗液中发酵抑制物的含量，观察石墨化碳的再生效果。采用离子色谱仪测定脱毒前后预处理液中的糖含量，计算石墨化碳脱毒对糖类的影响。脱毒后的预处理液经酿酒酵母乙醇发酵后，采用生物传感分析仪测定发酵液中的乙醇含量，计算乙醇发酵收率。【结果】竹材稀酸预处理液中甲酸、乙酸、乙酰丙酸、糠醛和5－羟甲基糠醛 5种发酵抑制物的总质量分数为15.87 g·L －1。石墨化碳对发酵抑制物的脱除率随着洗脱流速的升高而降低，在0.2 mL·min －1流速下可以脱除99.7%以上的发酵抑制物，而且石墨化碳可重复多次使用，使用5次后仍可以脱除95.7%以上的发酵抑制物。石墨化碳对糖类损失的影响不大，5种单糖损失率均在9%以内。脱除发酵抑制物后的预处理液可用于乙醇发酵，其中的葡萄糖可完全转化掉，发酵24 h 后，乙醇收率可达其理论值的85%以上。稀酸和乙醇对脱毒后石墨化碳的再生效果有限。【结论】石墨化碳能有效脱除竹材稀酸预处理液中的 5种发酵抑制物，其脱除率均在99%以上，对糖类损失的影响不大。脱毒后的预处理液可用于乙醇发酵，乙醇收率可达其理论值的85%以上。%Objective]In order to seek the environmental-friendly and effective removal of fermentation inhibitors form dilute acid pretreated bamboo spent liquor, graphitized carbon was used as detoxification media, and the ethanol fermentaion yields of before and after detoxification were compared.[Method]Moso bamboo powder was pretreated by 2%( mass of dry bamboo) sulfuric acid ( ratio of solid and solution is 1∶6 ) in 180 ℃ for 60 min to obtain the dilute acid pretreated spent liquor. The 5 fermentation inhibitors concentrations were determined by high performance liquid chromatography ( HPLC) . Graphitized carbon column was used to elute the inhibitors from the spent liquor. The elution process was carried out under normal temperature,air was used as eluent,and varies flow rate and elution times were adjusted. The inhibitors content of pretreated spent liquors after elution were determined by HPLC,and detoxification effects of the graphitized carbon were calculated. Moreover,in order to observe the regeneration effects of graphitized carbon,the graphitized carbon column after detoxification was flushed by dilute acid or ethanol at room temperature. The sugars concentrations of detoxified spent liquors were determined by ion chromatography to evalute the effects of graphitized carbon detoxified on sugars. The pretreated spent liquors after detoxification were fermented by Saccharomyces cerevisiae, biological sensor was used to determine the ethanol content in fermentation solution and the ethanol fermentation yield was calculated. [Result]The total fermentation inhibitors consisting of formic acid,acetic acid,levulinic acid,furfural and 5-hydroxymethyl furfural in dilute acid pretreated bamboo spent liquors were 15. 87 g·L -1 . Elution rate of fermentation inhibitors by graphitized carbon was decreased with the increasing of flow rate. More than 99. 7% of the fermentation inhibitors can be removed from the spent liquors under the flow rate of 0. 2 mL·min -1 . Graphitized carbon can be used repeatedly,even after using 5 times,still can remove more than 95. 7% of the fermentation inhibitors. The loss rates of five kinds of sugars were all less than 9% after the graphitized carbon elution process. The spent liquors after fermentation inhibitors removal can be used for ethanol fermentation,glucose can be converted to ethanol completely after 24 h fermentation,and the ethanol yield were more than 85%. The regeneration effects of dilute acid and ethanol on graphitized carbon after detoxification was limited. [Conclusion]Graphitized carbon can effectively remove the 5 fermentation inhibitors from dilute acid pretreated bamboo spent liquors,and the elution rates were all above 99%. The loss rates of sugars were low. The spent liquors after detoxification can be used for ethanol fermentation and the ethanol yield were more than 85%.
展开▼
