Radiation Chemistry of Methyl tert-Butyl Ether in Aqueous Solution

The chemical kinetics of the free-radical-induced degradation of the gasoline oxygenate methyl tert-butyl ether (MTBE) in water have been investigated. Rate constants for the reaction of MTBE with the hydroxyl radical, hydrated electron, and hydrogen atom were determined in aqueous solution at room...

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Bibliographic Details
Published in:	Environmental science & technology Vol. 38; no. 14; pp. 3994 - 4001
Main Authors:	Mezyk, Stephen P, Jones, Jace, Cooper, William J, Tobien, Thomas, Nickelsen, Michael G, Adams, J. Wesley, O'Shea, Kevin E, Bartels, David M, Wishart, James F, Tornatore, Paul M, Newman, Kimberley S, Gregoire, Kellie
Format:	Journal Article
Language:	English
Published:	Washington, DC American Chemical Society 15-07-2004 American Chemical Society (ACS)
Subjects:	Applied sciences Aqueous solutions Chemicals Chemistry Electrons Exact sciences and technology Groundwaters Hydrogen-Ion Concentration Hydroxyl Radical - chemistry Kinetics Methyl Ethers - analysis Methyl Ethers - chemistry MTBE Natural water pollution Oxidation-Reduction Pollution Pulse Radiolysis Radiation Solutions Waste Disposal, Fluid Water Pollutants, Chemical - analysis Water treatment and pollution Antiknock additive Ether Chemical degradation Free radical reaction Chemical reaction kinetics Kinetic model Additive Decontamination Electron irradiation Oxygenator Gasoline Reaction mechanism Radiochemical degradation Radiolysis Oxidation Water pollution Pulsed beam Degradation product Organic compounds Ground water
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Summary:	The chemical kinetics of the free-radical-induced degradation of the gasoline oxygenate methyl tert-butyl ether (MTBE) in water have been investigated. Rate constants for the reaction of MTBE with the hydroxyl radical, hydrated electron, and hydrogen atom were determined in aqueous solution at room temperature, using electron pulse radiolysis and absorption spectroscopy (•OH and e- aq) and EPR free induction decay attenuation (•H) measurements. The rate constant for hydroxyl radical reaction of (1.71 ± 0.02) × 109 M-1 s-1 showed that the oxidative process was the dominant pathway, relative to MTBE reaction with hydrogen atoms, (3.49 ± 0.06) × 106 M-1 s-1, or hydrated electrons, <8.0 × 106 M-1 s-1. The hydroxyl radical reaction gives a transient carbon-centered radical which subsequently reacts with dissolved oxygen to form peroxyl radicals, the rate constant for this reaction was (2.17 ± 0.06) × 109 M-1 s-1. The second-order decay of the MTBE peroxyl radical was 2k = (6.0 ± 0.3) × 108 M-1 s-1. These rate constants, along with preliminary MTBE degradation product distribution measurements, were incorporated into a kinetic model that compared the predicted MTBE removal from water against experimental measure ments performed under large-scale electron beam treatment conditions.
Bibliography:	istex:E904965B0F4D38452E4DFFB516461B697FFE309E ark:/67375/TPS-9NRN3VPG-7 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22) AC02-06CH11357 National Science Foundation (NSF)
ISSN:	0013-936X 1520-5851
DOI:	10.1021/es034558t