CHEMICAL EFFECTS OF CONTINUOUS AND PULSED ULTRASOUND IN AQUEOUS-SOLUTIONS

Molecules dissolved in water can undergo pyrolysis and free radical at tack when cavitation is produced by ultrasound. Macromolecules are als o degraded in the main chain. The yields of these processes depend on the volatility and hydrophobicity of the solutes and on the nature of the gas in the solution. The effects of 1 MHz (quartz) and 20 kHz (hor n) are compared; the yield ratio of oxidation to mechanical degradatio n is strongly dependent on the cavitation conditions. Chemical effects produced by pulsed ultrasound are also described and compared with ef fects observed in continuous irradiation experiments.