| Abstract
| - The chemical kinetics of the free-radical-induceddegradation of the gasoline oxygenate methyl tert-butylether (MTBE) in water have been investigated. Rate constantsfor the reaction of MTBE with the hydroxyl radical,hydrated electron, and hydrogen atom were determinedin aqueous solution at room temperature, using electronpulse 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 processwas the dominant pathway, relative to MTBE reactionwith hydrogen atoms, (3.49 ± 0.06) × 106 M-1 s-1, or hydratedelectrons, <8.0 × 106 M-1 s-1. The hydroxyl radicalreaction gives a transient carbon-centered radical whichsubsequently reacts with dissolved oxygen to form peroxylradicals, the rate constant for this reaction was (2.17 ±0.06) × 109 M-1 s-1. The second-order decay of the MTBEperoxyl radical was 2k = (6.0 ± 0.3) × 108 M-1 s-1.These rate constants, along with preliminary MTBEdegradation product distribution measurements, wereincorporated into a kinetic model that compared the predictedMTBE removal from water against experimental measurements performed under large-scale electron beam treatmentconditions.
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