Photoassisted dehalogenation of organo-chlorine compounds by paratungstate A in aqueous solutions

Nearly neutral aqueous solutions of 22 organo-chlorine compounds undergo photodegradation (lambda > 250 nm) catalyzed by paratungstate A,anion, [W7O24](6-), which was obtained by adjusting pH levels of the Na2WO4 solution to 6-7. In each case the organic:substrate was decomposed through dehalogenation. The rate of Cl- formation strongly depends on substrates. The photochemical redox reaction between paratungstate A and substrates proceeds:via precomplexation. The Langmuir-type dependence of the reaction rates on the concentration of substrates:provides a promising method for the dechlorination of alkyl- and aromatic-chloride compounds such as ClCH2CH2CH2Cl, C3H7Cl : and C6H5CH2Cl. (C) 2000 Elsevier Science B.V. All rights reserved.