Photosensitized reductive dechlorination of chloroaromatic pesticides

Photosensitized reductive degradation of chlorinated pesticides : 2,5-dichloro 1,4-dimethoxybenzene “chloroneb”, 1,1,1-trichloro-2,2-bis(4-chorophenyl) ethane “4,4′ DDT” and 2(4-chloro-2-methylphenoxy) methyl ethanoate “MCPA methyl ester” was studied in ethanol/water mixture as a solvent with N,N,N′,N′ tetramethylbenzidine as a photosensitizer. Sodium sulfite was used as a sacrificial electron-donor. The photoproducts obtained and the oxidation potential of the photoexcited sensitizer are in agreement with a mechanism involving an electron-transfer from the excited sensitizer to the pesticides. These results show that an electron-donor photosensitizer may increase the rate of photodegradation and help to remove the last traces of pollutant.