The Research On Preparation Of Ethanol By Corn Stalk Pretreated With ⁶⁰Co-?

In this paper,the pretreatment,detoxification,enzymatic saccharification,fermentation and optimization of fermentation process of corn stover fuel ethanol were systematically studied,and the simultaneous saccharification and fermentation of ethanol by irradiation corn straw was established.The research provides the research direction and reference data for the basic theory of ethanol production from corn stalks,which has economic value for the industrialization of corn stalk fuel ethanol.First,the effects of irradiation and comminution on the conversion rate of glucan by enzymatic hydrolysis of corn stover were studied.The results showed that the proportion of small particles in the samples increased gradually with the increase of irradiation dose.Under the same pulverization condition,r<0.075 mm particle of 0,400,800 kGy samples were 15.03%,53.22%,63.09%respectively.Meanwhile,the content of soluble glucan and xylan in corn stalk increased significantly with the increase of irradiation dose.The conversion rate of hydrolyzed glucan with 0 kGy and400 kGy increased with the decrease of particle size.And there were synergistic effects on the enzymatic hydrolysis of glucan from corn stalks.There were no significant difference and synergistic effect in the conversion rate of enzymatic hydrolysis of glucan with different particle size treated with 800 kGy.After 0¹000kGy irradiation treatment,the enzymatic hydrolysis conversion rate of corn straw increased with the irradiation dose,but there was no significant difference between800 kGy and 1000 kGy in the conversion rate.Secondly,the ethanol conversion rates of simultaneous saccharification and fermentation and the content of inhibitors of three kinds of detoxification-irradiated corn stover were investigated.The results showed that the detoxification treatment has a certain effect on the removal of corn stover inhibitors.And the ethanol conversion rates of different detoxification treatments were in descending order:NaBH₄ treatment?73.56%?,Ca?OH?₂ treatment?70.79%?and water washing?66.68%?,all of which are significantly higher than those?55.99%?without detoxification treatment.The detoxifications have a significant effect on increasing the ethanol conversion rate of simultaneous saccharification and fermentation.Five kinds of ethanol fermentation processes were studied.The order of ethanol conversion from high to low was:simultaneous saccharification and fermentation?55.99%?,step-by-step saccharification and fermentation?42.60%?,variable temperature simultaneous saccharification and fermentation?42.00%?,and semi-synchronized saccharification and fermentation.?39.66%?,fed-batch semi-synchronous saccharification and fermentation?35.54%?.Therefore,Simultaneous saccharification and fermentation is determined as the fermentation process.Finally,the response surface methodology was used to optimize the optimum conditions for the simultaneous saccharification and fermentation of ethanol from irradiated corn stover.The optimum process conditions:the amount of enzyme added was 1.74 mL/g,the fermentation time was 72 h,the fermentation temperature was 37?,the inoculum size was 16.64%,and the solids content was 5.64.Under this condition,the conversion rate of ethanol can reach 71.35%,which is very close to the theoretical prediction value of 73.11%.This shows that the response surface method is effectiveand reliable.