Purification Of Reed Ethanol Lignin And Preparation Of Epoxy Resin

Ethanol Pulping is the method of kinds of solvent pulping, with the advantages of small investment, high yield,efficient use of by-products, etc.,and can solve the pollution problems of traditional pulping effectively. In order to the high-value use of lignin, the lignin is needed to be purified further. This thesis mainly studied the technology of lignin isolation,purification of the waste liquid and using purified lignin to prepare epoxy resin. It was showed that the purity of lignin obtained by the optimized isolation process greatly improved after the lignin was purified by the enzymatic hydrolysis-mild acidolysis lignin purification procedure, and purified lignin was easier to react with epichlorohydrin.The lignin isolation method was that first a certain proportion of water was added to cooking waste liquor while pH value was controlled at about 4. The waste liquor was putted aside at a certain temperature, letting the lignin precipitate naturally. Separate the supernatant by the dumping method. Filter,wash and dry the naturally precipitated lignin in a vacuum oven. Remove entrained fines by filtering the obtained lignin to obtain isolated lignin, making it as the raw materials of purification.The optimum conditions for isolating lignin was that through studying the influence of dilution ratio, insulation temperature, precipitation time on the purity and yield of lignin by orthogonal test method, the optimized lignin isolation conditions were as followed, the temperature was 25?, volume ratio of added water and waste liquor was 0.8, pH value was about 4 (without acid), and precipitation time was 6h. The purity of lignin was 79.02%. The yeild of isolated lignin was 11.23% (based on oven dry reed material) or 54.83% (based on total lignin content of reed).The determination method of lignin relative purity was that it was determined by UV spectrophotometer. The linear regression equation of the concentration and UV absorbance value of ethanol lignin solution was that A=26.77c+0.0008. The correlation coefficient was that R2=0.9991.The lignin purification method was that purify the isolated lignin of the reed ethanol pulping with a lignin two-step purification procedure. This paper studied the law of the effect of the amount of enzyme, the enzymatic buffer pH value, reaction temperature and hydrochloric acid concentration of acid hydrolysis on the effect of purification. That the amount of enzyme was 0.004g·(g oven dry lignin)-1, the enzymatic buffer pH value was 6,enzymatic hydrolysis temperature was 30?, and hydrochloric acid concentration of acid hydrolysis was 0.05mol·L-1 were the optimal purification conditions. The purity of it was 91.89%,and the yield of it was 86.45%.Using IR, 1H-NMR spectrum and 13C-NMR spectrum of isolated lignin and purified lignin to comparatively analyze, it is proved that the sugars were effectively removed. The purity of lignin increased and the hydroxy and carboxy content of purified lignin decreased. In the purification process, guaiacyl constitutional units were stable compared to syringyl and p-hydroxyphenyl constitutional units.The epoxidation reaction of purified lignin was that use purified lignin and epichorohydrin to perpare epoxy resin. Conditions experiment was adopted to study the dosage of epichorohydrin,the dosage of sodium hydroxide,reaction temperature and reaction time on the influence of the epoxy value. It was showed that under the optimal conditions of 0.5g purified lignin,the amount of sodium hydroxide(mass fraction of 5%) 4.4ml,epichlorohydrin amount 0.75ml, reaction time 2h, temperature 45?, the measured lignin epoxy value was 0.345g/equivalent. Epoxy resin curing agent was triethylenetetramine. The quality of amine curing agent was 6.3 8g per 10Og epoxy which was 20% more than the theoretical value.Using IR, 1H-NMR spectrum and 13C-NMR spectrum of purified lignin and epoxy resin,it was proved that lignin epoxidation was successful. The resin was successfully introduced epoxy bonds, C-Cl bonds and other characteristic groups. In the epoxidation process, syringyl constitutional units were stable compared to p-hydroxyphenyl and guaiacyl constitutional units. After the epoxidation process, the proton percentage of lignin aromatic nucleus decreased. The 5th position proton of lignin aromatic nucleus was replaced by halogen.By the conductivity of lignin, it was effective to measure the amount of lignin phenolic hydroxyl group and carboxyl group.