Research On The Degradation Methods Of Ligno Cellulose Under Microwave

Ligno cellulose contains cellulose, hemi-cellulose,and lignin.Cellulose is the most abundant and renewable biomass in the biosphere. There is about30%cellulose, about17%hemi-cellulose, and about17%lignin in maize straw. Cellulose can be converted to glucose,and hemi-cellulose can be converted to glucose xylose.By degradation these reducing sugars further can be converted ethanol and other more valuable chemical materials.This article has firstly discussed the influence of the conventional heating and the microwave heating on the degradation of pure cellulose under catalysis HC1/H2O2. By single-factor experiments, the optimal degradation condition were received as follows: HCl/H2O2concentration5.0%, the ratio of solid to solvent300mg:100ml, stirring speed200r/min, reaction temperature100℃and reaction time2.Oh, The yield of reducing sugars is2.15mg/ml. IR and SEM analysis of the solid remains after pure cellulose degradation displays that there is not seriously destruction of the molecular structure of cellulose under microwave heating. SEM indicates microwave heating can help to enhance the scission of the chain of cellulose.therefore,more reducing sugars is obtained.Secondly,the lignocellulose degradation with H3PW12O40as catalyst under conventional heating and microwave heating have been conducted. By single-factor experiments, the optimal conditions has been found as following:mass of Maize straw:mass of heteroploly-acid:volume of aqueous solution is5.0g:1.0g:200ml,reaction temperature90℃and reaction time50min.The degradation yield is46.5%.Third, maize straw degradation by conventional heating in ionic liquid have been conducted. By single-factor experiment and orthogonal experimental design,the optimal conditions were obtained as follows:the ratio of solid to solvent5.Og:100ml, catalyst concentration7.4%, solvent pH of4.8, reaction temperature85℃and reaction time2.5h, The degradation yield is68.5%.Last, maize straw dissolution in two alkaline liquid systems have been conducted. Maize straw dissolution in NaOH-urea solution system was studied by conventional heating and microwave heating. A series of experiments on maize straw dissolution by microwave heating were finished and the following were the optimal conditions:the ratio of solid to solvent1.0g:25ml, dissolution temperature60℃and dissolution time1.0h.The dissolution yield of maize straw is48.6%. Under conventional heating, the optimal conditions were obtained as follows:the ratio of solid to solvent1.0g:25ml, dissolution temperature60℃and dissolution time6.Oh.The dissolution yield of maize straw is46.7%. IR and SEM analysis of the solid remains after dissolution displays that crystalline region of cellulose in maize straw by microwave heating is less than that by conventional heating, Therefore,the dissolution effect by microwave heating is better than that by conventional heating.Maize straw dissolution in NaOH-Thiourea solution system was also studied by conventional heating. the following were the optimal conditions:the ratio of solid to solvent1.0g:35ml, dissolution temperature50℃and dissolution time9.Oh.The dissolution yield is54.4%.Under microwave heating, the optimal conditions were obtained, dissolution time1.0h.The dissolution yield of maize straw is48.0%. The solid remains of maize straw dissolution in these two systems have been identified by IR and SEM analysis.The dissolution effect by conventional heating is better than that by microwave heating.