The studies for sonochemical reactor with dual-transducer have been conducted in recent years. The aim of these studies is to gain synergism which exceeds the effects of individual frequencies with superposition of dual-frequency. However the mechanism and conditions to do it are still unclear. In this study, the effect of dual frequency sonication on sonochemical reaction rate is examined. The production yield of I_3^- in aqueous solution of 0.1 M KI under sonication is used as a measurement of the sonochemical effects. To irradiate the solution with dual-frequency ultrasonic waves, the transducer for standing wave in frequency range of 24.1 kHz to 1170.0 kHz and the horn-type transducer (20 kHz) were used. We found that there is the synergetic effect at the frequency of the standing wave under 100 kHz and not in the range of 100 kHz to 500 kHz. We will discuss influence of harmonics and liquid flow on the synergetic effect.
