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 enhancements are observed6-fo...

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Bibliographic Details
Published in:Industrial & engineering chemistry research 1997-09, Vol.36 (9), p.3453-3457
Main Authors: Seymour, James D, Gupta, Ram B
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Industrial wastewaters
Pollution
Wastewaters
Water treatment and pollution
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Summary: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 enhancements are observed6-fold for chlorobenzene, 7-fold for p-ethylphenol, and 3-fold for phenol oxidation. The reaction rate enhancements are proportional to the diethyl ether−water partitioning coefficient of the pollutants. 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 pollutants toward the bubble−bulk interface. A first order reaction rate equation is proposed which can represent the observed enhancement with a good accuracy. A new sonochemical-waste-oxidation process is proposed utilizing the salt-induced enhancement.
ISSN:0888-5885
1520-5045
DOI:10.1021/ie970069o