Experiment Study On Producing Chitosan By Microwave Technology

Chitin is the most abundant natural polymer except cellulose in the earth. Chitosan, deacetylated product of chitin, is a kind of natural polysaccharide source, which has important valued in various areas. Micro-wave-Induced Reaction, a new technology which replaced traditional reaction applied in the organic reaction in late 80 th. Whether in our country or abroad, most of the research work on preparation chitosan based on chitin was concerned on original technology, instead of Microwave technology.This thesis expounds the experiment of making Chitosan by microwave technology and compared it with the general method. It was indicated that the Chitosan has the feature of higher deacetylation and higher viscosity by the method of microwave. First, several factors were emphasized which include the optimum sodium hydroxide concentration, different ratio of chitin and sodium hydroxide , different temperature, different power and reaction time. The optimum condition of preparation of Chitosan has been obtained by reaction with different power-time style. Thus preparation methods have high effect within less time and using least energy as well. The preparation time within fifteen minutes by microwave heating was considerably shortened as compared with the ordinary method by water bath, further the degree of deacetylation (DD) and the molecular weight of Chitosan was higher than that of chistosan prepared by general method. The experiment show that within fifteen minutes the deacelylation could reached 86% at different power by using about 45% sodium hydroxide solution and the ratio of chitin and sodium hydroxide .In addition, thinking about the inconvenientness of oxidation chitosan, we continue to prepare with different lower molecular weight. A water-soluble Chitosan was prepared using oxidative degradation by H2O2 under microwave radiation. Threefactor were tested: the concentration of H2O2, microwave power and reaction time. According to the experiment result, method by change power-time is the optimum. It was showed that the best condition were 5% H2O2, 5% Chitosan through changing of microwave power, and the microwave time about 3minutes.Although Microwave technology, as a new method which applied in the preparation of Chitosan, is still not mature at theory and lab, the popular of such technology would be coming in the nearest future. This thesis provides theory for the application on industry production.The effect of preparation of different molecular weight of Chitosan by oxidation degradation under microwave radiation is ideal and maybe possibly used in other field of Chitosan modification.