Abstract: In this paper, we demonstrate the temperature-sensitive precipitation of chitosan in chitosan-HCl solution. The precipitation and precipitation temperature were determined by the change of turbidity of the solution. The precipitation was governed by the degree of deacylation of chitosan, the concentration of chitosan and that of HCl, these effects could be interpreted by the DLVO theory. After precipitation, amidogen of chitosan was combined with HCl, which was proved by FTIR and changed to be amorphous, which was proved by the X-ray diffraction .The SEM of precipitation showed the novel form of chitosan.

Key words: Chitosan, Hydrochloric acid, Precipitation