title: Degradation of herbicide 2,4-dichlorophenoxybutanoic acid in the photolysis of [FeOH]2+ and [Fe(Ox)3]3- complexes: A mechanistic study.
abstract: In the present work the Fe(III)-assisted photodegradation of the herbicide 2,4-dichlorophenoxybutanoic acid (2,4-DB) has been studied by means of stationary (308 nm) and laser flash (355 nm) photolysis. The initial quantum yield of 2,4-DB photodegradation in [FeOH](2+) and [Fe(Ox)3](3-) systems was evaluated to be 0.11 and 0.17 upon 308 nm exposure, respectively. The prolonged photolysis of [FeOH](2+) and [Fe(Ox)3](3-) systems results in the complete degradation of 2,4-DB with almost complete mineralization of herbicide and its aromatic products in the case of [FeOH](2+) photolysis and the accumulation of some persistent aromatic products in the case of [Fe(Ox)3](3-) photolysis. For both systems the main primary products of 2,4-DB photolysis determined by liquid chromatography - mass spectrometry are products of the hydroxylation, the substitution of chlorine atom to OH group, the loss of aliphatic tail and the opening of benzene ring. The obtained results indicate ROS species (mainly OH radical) to be responsible for the herbicide photodegradation.
authors.affiliation: V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya str., 630090, Novosibirsk, Russian Federation; Novosibirsk State University, 2 Pirogova St., 630090, Novosibirsk, Russian Federation. Electronic address: pozdnyak@kinetics.nsc.ru.
authors.forename: Ivan
authors.initials: I
authors.lastname: Pozdnyakov
authors.affiliation: Novosibirsk State University, 2 Pirogova St., 630090, Novosibirsk, Russian Federation; International Tomography Center, 3a Institutskaya str., 630090, Novosibirsk, Russian Federation.
authors.forename: Peter
authors.initials: P
authors.lastname: Sherin
authors.affiliation: V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya str., 630090, Novosibirsk, Russian Federation.
authors.forename: Vjacheslav
authors.initials: V
authors.lastname: Grivin
authors.affiliation: V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya str., 630090, Novosibirsk, Russian Federation; Novosibirsk State University, 2 Pirogova St., 630090, Novosibirsk, Russian Federation.
authors.forename: Victor
authors.initials: V
authors.lastname: Plyusnin
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D002853:Chromatography, Liquid; D005290:Ferric Compounds / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D006900:Hydroxylation; D007700:Kinetics; D013058:Mass Spectrometry; D010782:Photolysis; D012989:Soil Pollutants / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D005290:Ferric Compounds; D006540:Herbicides; D012989:Soil Pollutants; D015084:2,4-Dichlorophenoxyacetic Acid; C004764:4-(2,4-dichlorophenoxy)butyric acid
keywords: 2,4-DB; Ferrioxalate complex; Hydroxyl radical; Iron hydroxo complex; Laser flash photolysis; Photodegradation