Study Of Pretreatment And Enzymatic Technics In The Process Of Using Lignocellulose To Ethanol

It has been the hotspot of study and application in last decades in the world, which is using lignocellulose to ethanol. In the paper, we study pretreatment and enzymatic technics on lignocellulose to ethanol with wood and rice hull as materials.Before enzymatic hydrolysis, by pretreating lignocellulose may remove lignin, dissolve hemicellulose or destroy crystal configuration of cellulose, for aggrandizing approachability surface, improving yield of hydrolysis. The influential factors of dilute acid pretreated rice hull and wood were studied including acid kinds, the ratio of solid to liquid, reaction time, temperature, acid concentration. Experimental results showed that: rice hull was favorable at 2 %(w/w) H₂SO₄,105℃,3 h, the content of hemicellulose and lignin in rice hull reduced 74.2 % and 18 % individually, the content of cellulose increased 15 %. But pretreatment of wood was advantageous at 2 %(w/w) HCl,105℃,3 h, the content of hemicellulose and lignin in wood reduced 78.4 % and 29.3 % individually, the content of cellulose increased 28.6 %. Then the enzymatic hydrolysis of rice hull and wood pretreated was studied. The influential factors of enzymatic hydrolyzing were pH, cellulose loading (FPA/g cellulose), hydrolyzing temperature, time of enzymatic hydrolysis, and the changes of material component and physics microcosmic configuration were observed. Experimental results showed that: at pH=4.8, 50℃, 48 h, 20 FPA(g rice hull^-1), cellulose of enzymatic hydrolysis was propitious to translate into glucose. After enzymatic hydrolysis, the content of cellulose felled 72 % in rice hull, the content of cellulose felled 65.4 % in wood.The result of rice hull pretreated with lime indicated that: rice hull with lime pretreated 6d at 80℃, the solubilization of rice hull increased about 50 %, the lime consumption was 0.167 g, the content of lignin was 9.3 %, reduced 62.4 %. But 90.8 % of cellulose retained in the rice hull, the content of hemicellulose little reduced after pretreated 4 d at 80℃. At 50℃, 48 h, 20 FPA (g rice hull^-1), the yield of enzymatic hydrolysis of rice hull with lime pretreated 6d at 80℃was 84.2 %.