Synergistic effect of discrete ultrasonic and HO on physicochemical properties of chitosan.

Synergistic degradation of chitosan by discrete ultrasonic and HO was investigated. The effects of ultrasonic time, ultrasonic power, chitosan concentration, and HO concentration were evaluated. The results revealed that ultrasonic power, HO concentration and ultrasonic time were positively correlated with degradation rate, while chitosan concentration was negative. The results of degradation kinetics revealed that the synergistic degradation process was consistent with the first-order reaction. Changes of characterization of chitosan were analyzed by FTIR, C NMR, XRD, SEM, and AFM analysis. The results indicated that the synergistic degradation did not destroy the pyranose ring. The crystal structure of degraded chitosan was destroyed, and the molecular conformation changed significantly. The antioxidant activity of the original and degraded chitosan was determined by DPPH and reducing power assays. The degraded chitosan had higher antioxidant activity. All results showed that the synergistic degradation of discrete ultrasound and HO was a feasible method for large-scale low molecular weight chitosan production.