Study On Removal Of Lignin From Corn Straw

China is a large agricultural country with abundant straw resources,among which the yield of corn straw ranks first.At present,corn straw is usually used as fuel or returned to the field in our country.But,the utilization rate is not high enough and the produced value is not great.However,a large amount of cellulose is contained in crop straw,which is a usable resource for producing ethanol.However,the existence of lignin limits the efficiency of cellulose hydrolysis in straw.Therefore,it is a key step to remove most lignin from straw by pretreatment.Three chemical pretreatment methods of straw were studied,including formic acidhydrogen peroxide pretreatment,urea pretreatment and ethanolamine pretreatment.The experimental results show that under the same conditions of enzymatic hydrolysis?p H = 5.0,1.5 g/L?10000 U/g?of the cellulose enzyme solution,43 ?,48 h?,the optimum condition of three pretreatment methods are?88% formic acid?v/v?,60 ?,6 h?for formic acid-hydrogen peroxide,?urea 9%?v/v?,60 ?,8 h?for urea,and?40%?v/v?ethanol amine,70 ?,10 h?for ethanol amine,respectively.After processing of maize straw,saccharification rate for above three methods are 61.13%,7.8% and 94.24% respectively.Though lignin could be removed for all these three methods,among which effect of pretreatment by ethanolamine is the best.The conditions for ethanolamine pretreatment were optimized by a response surface method.The best processing conditions are 51.65% ethanolamine?v/v?,72.11 ?,and 14 h reaction.After treatment,residual content of lignin is 0.57%,content of hemicellulose and cellulose are 15.63% and 74.63%,respectively.Under the condition of 40% ethanolamine?v/v?and 70?,the kinetic equation of removal lignin is established as R_L = 0.9642exp?-?₁t?+ 0.018exp?-k₂t?+ 0.0178exp?-k₃t?,which will provide a theoretical basis for ethanolamine to remove lignin from corn straw.Electron microscope experiments show that the content of components and apparent structure of corn straw changed significantly.Figure 43;Table 9;Reference 68...