Effect of Ultrasonic Frequency and Power Density for Degradation of Dichloroacetonitrile by Sonolytic Ozonation

The degradation of dichloroacetonitrile (DCAN) by means of the processes of sonolysis, ozonolysis and sonolytic ozonolysis was studied, and degradation rate constants were evaluated at various frequencies and power densities of ultrasound. The ultrasonic frequencies used were 35, 170, 283, 450, and 935 kHz. The power densities were in the range of 9.5 to 20 W/L. The degradation rate constants for the sonolytic ozonolysis were (3.1–4.4)×10-3 min-1 with the power density of 9.5 W/L and the ozone dose of 3.7 g/h. And the synergistic effect in sonolytic ozonolysis was significant at 35 and 283 kHz among the five frequencies. The sonolytic ozonolysis provided an extra oxidation mechanism by generating additional hydroxyl radicals, giving significant enhancement on the process. The calculated values of synergistic effect were 2.56 and 2.15 at 35 and 283 kHz, respectively.