New photochemical and electrochemical methods for the degradation of pesticides in aqueous media. Environmental applications

The development of new electrochemical and photochemical methods for the de contamination of natural water containing significant concentrations of aro matic pesticides is described. The electrochemical method is based on the e lectro-Fenton process, i.e. the simultaneous reduction Of O-2 and Fe3+ ions . Hydroxyl (OH.) radicals are electrosynthesized in aqueous solutions, foll owed by complete mineralization of the initial pollutants. The photochemica l methods involve either a direct photo degradation reaction of pesticides by UV light, or indirect photodegradation processes including H2O2 photolys is or photo-Fenton reagents (H2O2/Fe3+). Examples of the application of the se methods to chlorophenoxy acid herbicides and four aromatic pesticides (b endiocarb, pirimiphos-methyl, coumatetralyl, chlorophacinon) in aqueous med ia are given. Environmental applications are also presented. The performanc es of electrochemical and photochemical methods are compared.