Decrease in the rate of sonochemical oxidation with introduction of CO2

The effect of carbon dioxide (CO 2 ) in atmospheric gas on the rate of sonochemical oxidation was examined. An ultrasonic irradiation system has two types of effects, namely, physical and chemical effects. In some cases, chemical effects provide a negative performance. To suppress the chemical effect, CO 2 was introduced in a laboratory-scale setup using a syringe or a gas flow system. Sonochemical oxidation was performed at 2.4 MHz (24 W) and 200 kHz (15 W). The rate of oxidation was evaluated by potassium iodide (KI) dosimetry. The rate decreased with the introduction of CO 2 and sonochemical oxidation could not proceed at a mole fraction of CO 2 above 0.3 in the matrix. From the standpoint of practical use, in addition, a sensory test was carried out using 20% ethanol solution in a CO 2 –air atmosphere. No smell change was confirmed by the human sense of smell.