关键词: 毛竹, 稀酸预处理液, 发酵抑制物, 石墨化碳, 脱毒, 乙醇发酵

Abstract: [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%.

Key words: bamboo, dilute acid pretreated spent liquors, fermentation inhibitors, graphitized carbon, detoxification, ethanol fermentation