Reactive dyestuff degradation by combined sonolysis and ozonation

The degradation of a reactive dye by combined sonolysis (520 kHz) and ozona tion was studied using C.I. Reactive Black 5 as a model dye. It was found t hat the joint action of ultrasound and ozone induced a synergistic effect o n both the decolorization of the dye and the overall degradation process. D ue to the inefficiency of ultrasonic irradiation by itself to render any si gnificant degradation under the conditions employed, the synergy was attrib uted mainly to mechanical effects of ultrasound to enhance the mass transfe r of ozone in solution. The radical chain reactions taking place during the rmolysis of water and ozone in collapsing cavities may also have contribute d chemically to the synergy by providing additional decomposition pathways for ozone, and an excess of electron-deficient chemicals in solution. (C) 2 001 Published by Elsevier Science Ltd.