A mechanistic study of the photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid in aqueous solution

• Published in: Photochemical & photobiological sciences 2013-04, Vol.12 (4), p.684-689
• Main Authors: Yurkova, Maria P., Pozdnyakov, Ivan P., Plyusnin, Victor F., Grivin, Vycheslav P., Bazhin, Nikolay M., Kruppa, Alexandr I., Maksimova, Tatiana A.
• Format: Article
• Language: English
• Subjects: 2,4,5-Trichlorophenoxyacetic Acid - chemistry; beta-Cyclodextrins - chemistry; Biochemistry; Biomaterials; Chemistry; Chromatography, High Pressure Liquid; gamma-Cyclodextrins - chemistry; Herbicides - chemistry; Hydroxylation; Kinetics; Mass Spectrometry; Photolysis; Physical Chemistry; Plant Sciences; Ultraviolet Rays; Water - chemistry
• ISSN: 1474-905X; 1474-9092
• DOI: 10.1039/c2pp25204j

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.