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

Abstract

A new supermolecular assembly crystal, [C 6H 8N 2] 6H 3[PW 12O 40]·2H 2O (DMB–PWA), was synthesized with phosphotungstic acid (PWA) and 1,2-diaminobenzene (DMB) under hydrothermal conditions and was characterized by Fourier-transform infrared spectra (FTIR) and single-crystal X-ray diffraction analysis. DMB–PWA could effectively catalyze oxidative degradation of chitosan with H 2O 2 in the heterogeneous phase. The optimum degradation conditions were determined by orthogonal tests as follows: amount of chitosan 1.00 g, 30% (wt %); H 2O 2, 3.0 mL; dosage of catalyst, 0.06 g; reaction temperature, 85 °C; and reaction time, 30 min. The water-soluble chitosan with a viscosity-average molecular weight ( M v) of 4900 was obtained under the optimum degradation conditions and was characterized by FTIR, ultraviolet–visible diffuse reflection spectra (UV–vis DRS), and X-ray powder diffraction analysis.