Abstract: Chitosans with low molecular weight were prepared by homogeneous degradation of chitosan by microwave irradiation in different acid solution. The effects of various factors such as: reaction solution, H2O2/Chitosan ratio, microwave irradiation power and time on the degradation reaction were investigated in this paper. The results showed that chitosans with 10～100 thousand molecular weight were prepared in 1～6 minutes by microwave irradiation under the different reaction conditions. Moreover, the yield was higher and repetition was well. Keeping other reaction conditions fixed, the degradation velocity of chitosan in CH3COOH solution was the quickest and it was fit for preparing water-unsolvable chitosan with 10～ 50 thousand molecular weight while, the yield was over 80%. The degradation velocity in HCOOH solution was slowest and it was fit for preparing chitosan with more than 50 thousand molecular weight, while the yield was over 90%. The degradation velocity in HCl solution was in-between the other two.

Key words: homogeneous chitosan, microwave irradiation, degradation