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) meth yl ethanoate ''MCPA methyl ester'' was studied in ethanol/water mixtur e as a solvent with N,N;N',N' tetramethylbenzidine as a photosensitize r. Sodium sulfite was used as a sacrificial electron-donor. The photop roducts obtained and the oxidation potential of the photoexcited sensi tizer are in agreement with a mechanism involving an electron-transfer from the excited sensitizer to the pesticides. These results show tha t an electron-donor photosensitizer may increase the rate of photodegr adation and help to remove the last traces of pollutant.