Photochemistry of Herbicide 2,4,5-Trichlorophenoxyacetic Acid in Aqueous Solutions in the Presence of Cyclodextrins
M. P. YURKOVA,В В I. P. POZDNYAKOV,В В V. P. GRIVINВ В andВ В 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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