Study on the heterogeneous degradation of chitosan with H(2)O(2) catalyzed by a new supermolecular assembly crystal: [C(6)H(8)N(2)](6)H(3)[PW(12)O(40)].2H(2)O

Oxidative degradation of chitosan to the low molecular water-soluble chitosan over peroxotungstate as chemical scissors

Low molecular water-soluble chitosan was prepared by the depolymerization of chitosan in the presence of a series of catalysts with active W(O2) sites. Both the peroxo species [W2O3(O2)4]2- and {PO4[WO(O2)2]4}3- showed high efficiency in the degradation of chitosan, indicating that the degradation mechanism did not follow the radical mechanism. That means •OH is not the active species, which has been proven by the fluorescence spectra. H2O2 acted as an oxidant to regenerate the active W(O2) sites in the depolymerization of chitosan. The developed catalyst (TBA)3{PO4[WO(O2)2]4} is recoverable.

Plasma depolymerization of chitosan in the presence of hydrogen peroxide

The depolymerization of chitosan by plasma in the presence of hydrogen peroxide (H₂O₂) was investigated. The efficiency of the depolymerization was demonstrated by means of determination of viscosity-average molecular weight and gel permeation chromatography (GPC). The structure of the depolymerized chitosan was characterized by Fourier-transform infrared spectra (FT-IR), ultraviolet spectra (UV) and X-ray diffraction (XRD). The results showed that chitosan can be effectively degradated by plasma in the presence of H₂O₂. The chemical structure of the depolymerized chitosan was not obviously modified. The combined plasma/H₂O₂ method is significantly efficient for scale-up manufacturing of low molecular weight chitosan.