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Sonolytic Decomposition of Ozone in Aqueous Solution: Mass Transfer Effects

Weavers, Linda K. and Hoffmann, Michael R. (1998) Sonolytic Decomposition of Ozone in Aqueous Solution: Mass Transfer Effects. Environmental Science and Technology, 32 (24). pp. 3941-3947. ISSN 0013-936X. https://resolver.caltech.edu/CaltechAUTHORS:20150807-112624056

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Abstract

The sonolytic degradation of ozone (O_3) was investigated in both closed and open continuous-flow systems to examine effects of mass transfer on chemical reactivity in the presence of ultrasound. Degradation of O_3 followed apparent first-order kinetics at frequencies of both 20 and 500 kHz in all the systems. Degassing of O_3 was observed at 20 kHz due to the effects of rectified diffusion and larger resonant radii of the cavitation bubbles than at 500 kHz. Increased mass transfer of O_3 diffusing into solution due to ultrasound as measured by the mass transfer coefficient, k_La_2, was observed at both frequencies. At 20 kHz, an increase in mass transfer rates in the presence of ultrasound may be partially attributed to turbulence induced by acoustic streaming. However, the main process of increased gas−liquid mass transfer in the presence of ultrasonic waves appears to be due to the sonolytic degradation of O_3 creating a larger driving force for gaseous O3 to dissolve into solution. From first-order cyclohexene degradation kinetics obtained by sonolysis, ozonolysis, sonolytic ozonolysis, and comparing the large diameter of an O_3 diffusing gas bubble to the size of an active cavitation bubble, it appears that diffusing gas bubbles containing O_3 are not directly influenced by ultrasonic fields.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/es980620oDOIArticle
http://pubs.acs.org/doi/abs/10.1021/es980620oPublisherArticle
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 1998 American Chemical Society. Received for review June 16, 1998. Revised manuscript received September 21, 1998. Accepted September 29, 1998. Publication Date (Web): October 29, 1998. The authors thank Ralf Höchemer for valuable discussions and insight, Paul Sivilotti for help with statistical analysis, and anonymous reviewers for thoughtful comments. Financial supported provided by Defense Advanced Research Projects Agency (DARPA), the Office of Naval Research (ONR), the Electric Power Research Institute (EPRI), and the Department of Energy (DOE) is gratefully acknowledged.
Funders:
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)UNSPECIFIED
Office of Naval Research (ONR)UNSPECIFIED
Electric Power Research Institute (EPRI)UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Issue or Number:24
Record Number:CaltechAUTHORS:20150807-112624056
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150807-112624056
Official Citation:Sonolytic Decomposition of Ozone in Aqueous Solution:  Mass Transfer Effects Linda K. Weavers and Michael R. Hoffmann Environmental Science & Technology 1998 32 (24), 3941-3947 DOI: 10.1021/es980620o
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59316
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:07 Aug 2015 20:23
Last Modified:03 Mar 2020 13:01

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