Sonocatalysis – The effects of sound generated waves on catalytic chemistry

Power Ultrasound During the sonication of liquids, the accoustic wavelength range between approx. 110 and 0.15 mm for frequencies of 18kHz and 10Mhz. This is significantly higher than those of molecular dimensions, resulting in that there is between the molecules and the accoustic field no direct coupling of chemical species. The effects of sonication are mostly generated by the ultrasonic cavitation in liquids (picture 1). Therefore, for the ultrasound catalysis at least one reagent in a liquid phase is necessary. Cavitation erosion on particle surfaces generates unpassivated, highly reactive surfaces. Short periods of high temperatures and pressures contribute to a molecular decomposition and increase the reactivity of many chemical substances. Ultrasonic irradiation can also be used to prepare the catalysts, e.g. to produce aggregates of fine-size particles.