The chemical kinetics of the free-radical-inducedde
gradation of the
gasoline oxy
genate methyl
tert-butylether (MTBE) in water have been investi
gated. Rate constantsfor the reaction of MTBE with the hydroxyl radical,hydrated electron, and hydro
gen atom were determinedin aqueous solution at room temperature, usin
g electronpulse radiolysis and absorption spectroscopy (
ges/entities/bull.gif">OH and e
-aq)and EPR free induction decay attenuation (
ges/entities/bull.gif">H) measurements.The rate constant for hydroxyl radical reaction of (1.71± 0.02) × 10
9 M
-1 s
-1 showed that the oxidative processwas the dominant pathway, relative to MTBE reactionwith hydro
gen atoms, (3.49 ± 0.06) × 10
6 M
-1 s
-1, or hydratedelectrons, <8.0 × 10
6 M
-1 s
-1. The hydroxyl radicalreaction
gives a transient carbon-centered radical whichsubsequently reacts with dissolved oxy
gen to form peroxylradicals, the rate constant for this reaction was (2.17 ±0.06) × 10
9 M
-1 s
-1. The second-order decay of the MTBEperoxyl radical was 2
k = (6.0 ± 0.3) × 10
8 M
-1 s
-1.These rate constants, alon
g with preliminary MTBEde
gradation product distribution measurements, wereincorporated into a kinetic model that compared the predictedMTBE removal from water a
gainst experimental measurements performed under lar
ge-scale electron beam treatmentconditions.