Sonochemical degradation of CCl4 in an Ar-H2 dissolved aqueous solution.

The sonochemical degradation of CCl4 in an Ar-H2 dissolved aqueous solution was investigated. In particular, the proportion of dissolved H2 in the total dissolved gas was analyzed as a key variable. The observed non-linear correlation between the degradation rate of CCl4 and H2 proportion in the Ar-H2 mixed gas system suggested two opposing effects of H2 on the system. As the positive effect of H2, the increase in the concentration of H radicals formed from H2 could contribute to the reductive degradation of CCl4. On the other hand, as the negative effects of H2, the decreases in bubble number and bubble temperatures could suppress the formation of H radicals and the degradation of CCl4. This interpretation was supported by the multiple experimental results of sonoluminescence (SL) measurement, H2O2 formation, quantitative evaluation of dissolved gas concentration, and analysis of bubble temperature and carbon-containing products in the Ar-H2 mixed gas system.