Removal The Acidic Hydrolysis Product Of Lignocellulose By Fenton Oxidation Method

Previous research has shown that cellulose,hemicellulose,and lignin were obtained by the acid treatment of lignocellulosic materials and subjected to the degradation to produce the products,which have inhibitory effects on the subsequent ethanol fermentation,especially the arenol compounds.In order to investigate the removal mechanism of such inhibitors by the Fenton system and explore the effect on their removal,this paper focuses on the ability of the typical acidic hydrolysis products from lignocellulose to trap hydroxyl radicals on the basis of methylene blue and Fenton reagent system.In addition,the acid hydrolysis products were selected as related model compounds to study the the effects of the Fenton reagent on the removal of phenolic inhibitors from enzymolysis and fermentation,and then the reaction process and mechanism were proposed.The main conclusions are as follows:（1）The conversions of cellulose,hemicellulose,and lignin from pine wood chips by acid treatment were 10.24%,77.39%,and 6.20%,respectively.In the treated hydrolyzate,the carbohydrates are xylose,glucose,mannose,arabinose,and galactose furan compounds are mainly furfural and a small amount of 5-hydroxymethylfurfural.In addition,arenols include vanillin,syringaldehyde,and 4-hydroxybenzaldehyde,and fatty acids mainly consist of acetic acid and small amounts of formic acid and levulinic acid.（2）Vanillin,furfural,and glucose were selected as related model compounds form typical acid hydrolysis products.In the methylene blue and Fenton reagent systems,the ability of several substances to capture·OH was as follows:vanillin,furfural,and glucose.When the reaction was performed at a p H of 3.0,and the concentration of Fe²⁺and H₂O₂ of 0.03 mmol/L and 0.24 mmol/L,reapectively,and vanillin and furfural existed at concentrations of 0.06 mmol/L and 0.096 mmol/L,respectively,the removal rates were 92.65%and 100%,respectively.When vanillin and furfural were present at the same time,the removal rates were 82.76%and 88.98%,respectively.When H₂O₂concentration was 0.12 mmol/L,the removal rate was 67.08%and 97.80%,respectively.（3）The arenol compounds before Fenton’s reagent treatment will affect cellulase activity.The higher the phenol concentration,the lower the enzyme activity.The content of reducing carbohydrates in the enzymolysis process increases with the increase of the oxidative degradation of arenols by Fenton’s reagent.The oxidative degradation of arenols by Fenton’s reagent can reduce the inhibitory effect of arenols on the enzymolysis process and promote the enzymolysis of cellulose.The production of reducing carbohydrates facilitates the enzymatic reaction.（4）The arenol solution reduces the utilization rate of glucose in the fermentation process or even completely inhibits the fermentation process,hence the growth of bacteria is inhibited and the presence of arenol solution affects the production of ethanol in the fermentation process.Fenton oxidation studies showed that the addition of theoretical oxidation of 37.5%Fenton reagent to oxidize arenol solution was superior to that of 25%and 50%to glucose utilization,cell growth,and ethanol yield.In the fermentation process,the conversion of glucose is higher than that of ethanol,suggesting that in the fermentation process,yeasts produce other by-products in addition to fermenting glucose to produce ethanol.