The Technology Of Production Of Ethanol From Corn Cob

The main work in this thesis includes the following several aspects:namely different pretreatment technology, enzymatic hydrolysis of hemicellulose, fermentation of xylose to ethanol, simultaneous saccharification and fermentation (SSF) of cellulose to ethanol.The purpose of pretreatment is to remove lignin, reduce the lose of hemicellulose and cellulose, improve the enzymatic hydrolysis yield of hemicellulose and cellulose. By optimizing the pretreatment conditions with alkali liquor, the results showed that corn cob residue yield was59.74%, the remaining rate of hemicellulose was56.60%, the remaining rate of cellulose was86.20%, the removal rate of lignin was88.17%in corn cob. By optimizing the pretreatment conditions of fermentation with white rot fungus, the results showed that corn cob residue yield was63.82%, the remaining rate of hemicellulose was44.52%, the remaining rate of cellulose was82.45%, the removal rate of lignin was76.52%in corn cob.Enzymatic hydrolysis of hemicellulose and cellulose was carried out by xylanase and cellulose, respectively. The product of the hydrolysis was usually xylose and glucose, respectively.The factors that affect the enzymatic hydrolysis of hemicellulose with xylanase include additives, the enzyme addition, enzymatic hydrolysis time, liquid to solid ratio(substrate concentration). By optimizing the enzymatic hydrolysis conditions, enzymatic hydrolysis yield of pretreatment residue with alkali liquor and white rot fungi was86.62%and62.05%respectively. Compared with unoptimizing conditions, enzymatic hydrolysis yield improved44.17%and30.48%, respectively.Xylose obtained through enzymatic hydrolysis of alkali liquor and white rot fungus pretreatment residue,which was used to ferment to ethanol. when xylose concentration was30g/L,fermentation time was60h, xylose was fermented to11.29g/L ethanol and11.32g/L, respectively.The ethanol was produced through simultaneous saccharification and fermentation (SSF) of alkali liquor pretreatment cellulose. The results showed that ethanol concentration achieved28.80g/L within60h, the ethanol yields reached0.5005g/g (ethanol/cellulose),which was88.33%of theoretical yield. The ethanol was produced through simultaneous saccharification and fermentation (SSF) of white rot fungus pretreatment cellulose. The results showed that ethanol concentration achieved20.32g/L within60h. The ethanol yields reached0.4294g/g (ethanol/cellulose), which was75.78%of theoretical yield.