Effect of carbon tetrachloride on sonochemical decomposition of methyl orange in water.

Two types of sonicators were used for the sonochemical decomposition of methyl orange (MO) in the presence and absence of carbon tetrachloride (CCl4): One is a 45kHz ultrasonic cleaning bath (a low intensity sonicator) and the other is a 200kHz ultrasonic reactor (a high intensity sonicator). It was clearly confirmed that the rates of the sonochemical decomposition of MO increased with increasing the concentration of CCl4 in both sonicators. The enhancement effect of CCl4 was much higher in the high intensity sonicator than in the low intensity one: by the addition of 100ppm of CCl4, the decomposition ratio of MO with the high intensity sonicator became 41 times larger, while that with the low intensity sonicator became 4.8 times larger. Based on the obtained results, it was suggested that the formed cavitation phenomenon was different between sonicators. It was also suggested that the sonochemical decomposition of MO in the presence of CCl4 would be useful to evaluate the sonochemical efficiency, because the rate of MO decomposition can be effectively enhanced by the sonolysis of CCl4.