A Mechanistic Study of the Photodegradation of Herbicide 2,4,5-Trichlorophenoxyacetic Acid in Aqueous Solution
Photochemical & Photobiological Sciences
, E-ISSN: 1474-9092
Yurkova Maria P.
Pozdnyakov Ivan P.
Plyusnin Victor F.
Grivin Vycheslav P.
Bazhin Nikolay M.
Kruppa Alexandr I.
Maksimova Tatiana A.
Voevodsky Institute of Chemical Kinetics and Combustion SB RAS
Photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aqueous solution was investigated by stationary (254 nm) and nanosecond laser (266 nm) flash photolysis techniques. It was shown that in the primary photochemical step both photoionization (which generates a hydrated electron–radical cation pair) and heterolytic cleavage of a C–Cl bond takes place. The major products of substitution of one of the chlorine atoms in the 2-, 4- or 5-position by a hydroxyl group as well as the products of hydroxylation of the benzene ring in 3- and 6-positions were identified by HPLC and LC-MS methods. The complexation of 2,4,5-T with β- and γ-cyclodextrins (β(γ)CD) was investigated. The influence of such complexation on the quantum yield of herbicide photolysis and on the ratio of photodegradation products was determined.