Photochemistry of Herbicide 2,4,5-Trichlorophenoxyacetic Acid in Aqueous Solutions in the Presence of Cyclodextrins
M. P. YURKOVA, I. P. POZDNYAKOV, V. P. GRIVIN and V. F. PLYUSNIN
Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences,
Ul. Institutskaya 3, Novosibirsk 630090 (Russia)
yurkova@kinetics.nsc.ru
Keywords: photochemistry, photodegradation, herbicides, photoionization, hydrated electron, laser flash photolysis, cyclodextrins, inclusion complexes
Pages: 659–664
Abstract
Photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-Т) in aqueous solutions was studied by means of steady-state and nanosecond laser flash photolysis. It was demonstrated that the primary photochemical act involves one- and two-photon ionization of the herbicide and the formation of the hydrated electron/radical cation pair. In oxygen-free solutions, hydrated electron disappears due to capturing by the initial compound, whereas the radical cation gets hydrolyzed with water to form a long-living phenoxyl radical. We also studied the formation of 2,4,5-Т complexes with β- and γ-cyclodextrins (2,4,5-Т-β(γ)-CD) and the effect of this process on the rate of the steady-state photolysis of the herbicide.
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