Synergetic effect of ozone and ultrasonic radiation on degradation of chitosan

Under conditions of continuous ozone gas application and constant ultrasonic radiation (UR), chitosan was effectively degraded. The existence of a synergetic effect of ozone and ultrasonic radiation on the degradation of chitosan was demonstrated by means of determination of viscosity-average molecular weight. The efficiency of the ozone and ultrasonic radiation treatment compared with acid hydrolysis on degradation of chitosan was investigated. In addition, the structure of the degraded chitosan was characterized by FT-IR and 13C NMR spectral analyses. The whole initial chitosan's monomer structure still existed in the resulting degraded chitosan with different low molecular weight. The pilot study of the chemical stability of the degraded chitosan was carried out. There was no significant change of the total degree of deacetylation (DD) of degraded chitosan compared with the initial chitosan. The combined O3/UR technique is promisingly suitable for scale-up manufacture of low-molecular-weight chitosan.