Degradation of chitosan by swirling cavitation

• The chitosan solution can be degraded effectively by swirling cavitation.
• The degradation efficiency increased with decreasing solution concentration.
• The optimum conditions were obtained by Orthogonal test.
• There was no obvious modification of chemical structure of degraded chitosan.

In the present work, degradation of chitosan by swirling cavitation was investigated. In swirling cavitation, the cavitating device of the turbine was used to generate cavitation. The effects of initial concentration, temperature, pressure, and treatment time on the degradation of chitosan were investigated initially. It was found that the degradation efficiency increased with increasing temperature, treatment time and pressure, and decreasing solution concentration. In addition, the optimum conditions were determined on the basis of orthogonal tests as follows: solution concentration 1 g·L− 1, pressure 0.4 MPa, treatment time 3 h and temperature 60 °C, the intrinsic viscosity reduction rate of chitosan was 83.65% under the optimum conditions. The structures of initial and degraded chitosan were characterized with Fourier-Transform infrared spectra (FT-IR). The present work establishes that swirling cavitation can be effectively used for the degradation of chitosan.Industrial relevanceIndustrial relevance of medicine, food, chemical industry, cosmetic, water treatment, metal extraction and recycling, biochemical and biomedical engineering and many other fields.