Sonolysis of an aqueous mixture of trichloroethylene and chlorobenzene

The effect of the initial concentration on the ultrasonic degradation of two volatile organic compounds trichloroethylene (TCE) and chlorobenzene (CB) was investigated. At higher concentrations, slower sonolysis rates were obtained due to the lowering of the average specific heat ratio γ of the gas inside the cavitation bubbles. Furthermore, the effect of different concentrations of CB on the sonolysis of 3.34 mM TCE and the effect of different concentrations of TCE on the sonolysis of 3.44 mM CB was examined. The presence of CB lowered the sonolysis rate of TCE, while the sonolysis rate of CB did not decrease by TCE addition. An even higher sonolysis rate was obtained for 3.44 mM CB in the presence of 0.84 mM TCE than without TCE. The explanation for the different effects of both volatile organics on each other’s sonolysis rate is thought to be the difference in reaction rate of TCE and CB with the radicals formed during sonolysis. The effect of TCE on the sonolysis rate of CB by lowering the γ value is compensated by an increased indirect degradation of CB by radicals formed out of TCE. The decreased thermal degradation and the increased indirect radical degradation of CB in the presence of TCE is demonstrated by determining the kinetics of the degradation products styrene and dichlorobenzene.