Preparation of chitosan with low molecular weight by γ-ray irradiation in different solutions

The chitosan with low molecular weight was prepared by γ-ray degradation method. The influence of irradiation dose on the radiation degradation of chitosan studied in heterogeneously aqueous solutions of H2O2, NaBH4 and L-α-alanine. The degradation products were characterized by FTIR and UV-VIS. The degradation of chitosan is the most quickly in the H2O2, because of the concentrations of OH radicals increased. The white degree of irradiation degraded chitosan is the highest in NaBH4 or L-α-alanine solution. UV and FTIR analyses manifest that no obvious differences in the main chain structure and deacetylation degree between irradiated and un-irradiated chitosan, but the carbonyl group forms in the molecules of the irradiated chitosan. The results show that γ-ray can be expected as an effective way to control the molecular weight of chitosan. (authors)