Electrochemical Reduction of Atrazine at Carbon and Silver Cathodes

Abstract

Since its introduction in the 1950s, atrazine (6-chloro-N2-ethyl-N4-(1-methylethyl)-1,3,5-triazine-2,4-diamine) has become one of the mostly widely used pesticides in the world. Although atrazine has been banned in the European Union since 2004, it is still applied extensively in the US, and can be detected in water sources, soil, and even air.1 Environmental persistence of atrazine and its metabolites has caused contamination to spread away from regions of herbicide application, and some studies have shown evidence of endocrine disruption in amphibians exposed to these chemicals.1 For these reasons, the degradation of atrazine to less environmentally harmful compounds is of great concern. In this study, we have employed electrochemical reduction for the degradation of atrazine at different cathode materials. Previous electrochemical studies of atrazine have been performed at mercury cathodes, and were successful in both the detection of atrazine by means of square-wave voltammetry and its degradation through controlled-potential (bulk) electrolyses.2-4 At mercury cathodes, long electrolyses resulted in both the breaking of the carbon–halogen bond and reduction of the triazine ring.4 To avoid the use of mercury, we have explored the use of carbon and silver cathodes; glassy carbon provides a simple, environmentally friendly alternative, whereas silver has been shown to be catalytic for the cleavage of carbon–halogen bonds. Reduction of atrazine at carbon and silver cathodes, respectively, in dimethylformamide (DMF) containing 0.050 M tetramethylammonium tetrafluoroborate (TMABF4), results in a single cyclic voltammetry peak at –1.77 or –1.62 V vs. a Cd(Hg) reference electrode. Investigations of the products arising from controlled-potential electrolysis by means of gas chromatography–mass spectrometry indicate the presence of dechlorinated atrazine (N2-ethyl-N4-(1-methylethyl)-1,3,5-triazine-2,4-diamine) after electrolyses at both carbon and silver cathodes.