Abstract:

In this research, the effect of oxygen on the degradation of chitosan by swirling cavitation under different
conditions of initial concentration of chitosan solution, pH, temperature, inlet pressure and cavitation time was studied.
The results showed that low initial concentration of chitosan solution resulted in better degradation efficiency of swirling
cavitation. When the following conditions were used: solution pH, 4.4; temperature, 70 ℃; inlet pressure, 0.4 MPa; and
cavitation time 3 h, chitosan solution showed the largest decline in intrinsic viscosity. Under each of the tested conditions,
continuous feeding of oxygen significantly augmented the decrease in intrinsic viscosity, which could result in the maximum
improvement of 35.36%. The effect of oxygen on the degradation of high chitosan concentration was more significant. pH
impact on the degradation of chitosan was weakened, and the reaction rate was greatly accelerated in the early stage of the
reaction as a result of increased oxygen supply. The major chain structure and functional groups of chitosan after degradation
were not changed.

Key words: oxygen, swirling cavitation, degradation, chitosan