Abstract: Chitosan was prepared in this paper from chitin by applying microwave technique. Ethanol was employed to soak the chitin before microwave treatment, and the condition of the ethanol pretreatment was studied systematically for the first time. Through single-factor experiments and orthogonal experiment, the effects of some factors on the degree of deacetylation and molecular weight of the chitosan product were studied. The optimized conditions of preparing chitosan product with relatively high degree of deacetylation and high molecular weight were provided, as follows (with microwave power being 462W): reaction time under microwave treatment 20min, concentration of NaOH 50%, soaking time of ethanol 2.5h and concentration of ethanol 80%. Under such conditions, degree of deacetylation and molecular weight of the chitosan product were 77.07% and 4.313×105, respectively, and the yield of the product was 68.98%.

Key words: microwave, deacetylation, ethanol pretreatment, chitin, chitosan