OXIDATION OF AQUEOUS POLLUTANTS USING ULTRASOUND - SALT-INDUCED ENHANCEMENT

Ultrasound can be used to oxidize aqueous pollutants; however, due to economic reasons, higher oxidation/destruction rates are needed. This study reports enhancements of reaction rates by the addition of sodium chloride salt. Using 20 kHz ultrasound, large salt-induced enhancemen ts are observed-6-fold for chlorobenzene, 7-fold for p-ethylphenol, an d 3-fold for phenol oxidation. The reaction rate enhancements are prop ortional to the diethyl ether-water partitioning coefficient of the po llutants. It appears that the majority of oxidation reactions occur in the bubble-bulk interface region. The addition of salt increases the ionic strength of the aqueous phase which drives the organic pollutant s toward the bubble-bulk interface. A first order reaction rate equati on is proposed which can represent the observed enhancement with a goo d accuracy. A new sonochemical-waste-oxidation process is proposed uti lizing the salt-induced enhancement.