Degradation of 2,4-dichlorophenoxyacetic acid by ionizing radiation: influence of oxygen concentration.
Ionizing radiation has been proved as a promising method for the degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The gamma-radiolytic decomposition and chloride formation follows an apparent first order kinetic, kde/kCl = 3. For complete removal of 500 microM 2,4-D, a dose of 4 kGy is required. Phenolic intermediates (2,4-dichlorophenol, the isomers 2-chloro-4-hydroxy- and 4-chloro-2-hydroxy phenoxyacetic acid and three hydroxylation products of 2,4-D) are formed. Using oxygen saturation during irradiation, they are removed again with a dose of 4 kGy. For the formation of the main organic product acetic acid a reaction mechanism is discussed. Oxygen concentration enhances strongly fragmentation and mineralization. A reduction of 36% TOC could be achieved.
Zona
R
R
Institute for Theoretical Chemistry and Structural Biology, University of Vienna, Austria.
Solar
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S
Gehringer
P
P
D015084:2,4-Dichlorophenoxyacetic Acid / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D011839:Radiation, Ionizing; D018508:Water Purification / Q000379:methods*
D006540:Herbicides; D015084:2,4-Dichlorophenoxyacetic Acid; D010100:Oxygen