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Synergistic Effects of Sonolysis Combined with Ozonolysis for the Oxidation of Azobenzene and Methyl Orange

Destaillats, Hugo and Colussi, A. J. and Joseph, Jiju M. and Hoffmann, Michael R. (2000) Synergistic Effects of Sonolysis Combined with Ozonolysis for the Oxidation of Azobenzene and Methyl Orange. Journal of Physical Chemistry A, 104 (39). pp. 8930-8935. ISSN 1089-5639. http://resolver.caltech.edu/CaltechAUTHORS:20150623-154759244

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Abstract

Most advanced oxidation processes (AOP) readily decolorize but are unable to mineralize aqueous azo dye solutions. The extent of mineralization -- measured as total organic carbon (TOC) losses -- during the 500-kHz sonication of azobenzene or methyl orange solutions increases from 20% to more than 80% in the presence of O_3. The abatement of the total organic load by the joint action of ultrasound and O_3 amounts to chemical synergism. Since TOC losses are not enhanced by ozonation followed by sonication and ground-state O atoms -- that are produced by sonochemical O_3 thermolysisare relatively unreactive, synergism likely involves the fast oxidation by ozone of free radical or unsaturated species generated by •OH radical attack on otherwise refractory products. Some of these products probably are saturated mono- and dicarboxylic acids, known to be resistant to O_3 oxidation. Nitrobenzene and benzoquinone, two rather persistent byproducts of sonolysis, are rapidly and completely mineralized by the combined oxidation treatment. Thus, direct ozonation of unsaturated sonolytic byproducts also accounts for part of the observed enhancement of the extent of mineralization. The anomalous kinetic behavior of the sonochemical degradation of benzoquinone (in the absence of O_3) is accounted for by its particularly high reactivity toward the relatively inert HO_2• and O_2^-• radicals.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp001415+DOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp001415%2BPublisherArticle
ORCID:
AuthorORCID
Colussi, A. J.0000-0002-3400-4101
Hoffmann, Michael R.0000-0002-0432-6564
Additional Information:© 2000 American Chemical Society. Received: April 14, 2000; In Final Form: July 19, 2000. Financial support provided by the Department of Energy (DOE 1963472402) and the U.S. Navy (N 47408-99-M-5049) is gratefully acknowledged. J.M.J. thanks the ICSC World Laboratory for a research fellowship.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)1963472402
Office of Naval Research (ONR)N 47408-99-M-5049
ICSC World LaboratoryUNSPECIFIED
Record Number:CaltechAUTHORS:20150623-154759244
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150623-154759244
Official Citation:Synergistic Effects of Sonolysis Combined with Ozonolysis for the Oxidation of Azobenzene and Methyl Orange Hugo Destaillats, A. J. Colussi, Jiju M. Joseph, and Michael R. Hoffmann The Journal of Physical Chemistry A 2000 104 (39), 8930-8935 DOI: 10.1021/jp001415+
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58489
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:28 Jul 2015 19:58
Last Modified:28 Jul 2015 19:58

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