Kinetics and Mechanism of the Sonolytic Degradation of Chlorinated Hydrocarbons: Frequency Effects

The kinetics of the sonolytic degradation of aqueous solutions of carbon tetrachloride and hexachloroethane (C_2Cl_6) were investigated at six different frequencies over the range from 20 to 1078 kHz. The rates of degradation of CCl_4 and C_2Cl_6 were shown to increase with increasing frequency with optimal degradation rates at 500 kHz. At 205 kHz, the relative rates of sonolytic degradation of the three chlorinated methanes followed the order of CCl_4 > CHCl_3 > CH_2Cl_2. Hexachloroethane, which was formed as the primary intermediate in the degradation of CCl_4, was degraded at a rate comparable to that of CCl_4 at all six frequencies.