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 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) x 10(9) M(-1) s(-1) showed that the oxidative process was the dominant pathway, relative to MTBE reaction with hydrogen atoms, (3.49 +/- 0.06) x 10(6) M(-1) s(-1), or hydrated electrons, <8.0 x 10(6) 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) x 10(9) M(-1) s(-1). The second-order decay of the MTBE peroxyl radical was 2k = (6.0 +/- 0.3) x 10(8) 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 measurements performed under large-scale electron beam treatment conditions.
Department of Chemistry and Biochemistry, California State University at Long Beach, 1250 Bellflower Boulevard, Long Beach, California 90840, USA. Smezyk@csulb.edu
Stephen P
SP
Mezyk
Jace
J
Jones
William J
WJ
Cooper
Thomas
T
Tobien
Michael G
MG
Nickelsen
J Wesley
JW
Adams
Kevin E
KE
O'Shea
David M
DM
Bartels
James F
JF
Wishart
Paul M
PM
Tornatore
Kimberley S
KS
Newman
Kellie
K
Gregoire
Daniel J
DJ
Weidman
D004583:Electrons; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D008738:Methyl Ethers / Q000032:analysis* / Q000737:chemistry*; D010084:Oxidation-Reduction; D011675:Pulse Radiolysis; D012996:Solutions; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis*
D008738:Methyl Ethers; D012996:Solutions; D014874:Water Pollutants, Chemical; C043243:methyl tert-butyl ether; D017665:Hydroxyl Radical