TiO2/BaTiO3-assisted photocatalytic mineralization of diclofop-methyl on UV-light irradiation in the presence of oxidizing agents

Gas chromatograph-mass spectroscopic identification of intermediate products in the degradation of diclofop-methyl and the kinetics of the reaction has been investigated. Formation of 4-[(2,4-dichlorophenoxy) phenoxyl ethane and (2,4-dichlorophenoxy) phenol was investigated. The other intermediate products are 2,4-dichlorophenol, 2,4-dichlorobenzene, phenol and acetic acid have been ascertained. The decrease in the concentration of the parent/intermediate compounds is followed by UV-vis spectral study and the supportive information on the functional groups in the intermediates has been obtained from IR-spectroscopy. Degradation process proceeds with oxidation-reduction reaction by the attack of OH center dot, H-center dot, O-2(center dot-) free radicals, which are photogenerated on the UV-light illuminated TiO2/BaTiO3 photocatalysts particles in aqueous medium. In this presentation another wide band gap semiconductor BaTiO3 is shown to have comparable photocatalytic efficiency. The oxidizing agents are added to accelerate the rate of the reaction by enhancing the formation of free radicals. Based on the intermediates formed in the process of degradation, a suitable mechanism has been proposed. (C) 2008 Elsevier B.V. All rights reserved.