Electrochemical oxidation of paraquat in neutral medium

Steel, Pt and pelleted Co2FeO4 electrodes were used for the electrochemical oxidation of paraquat in aqueous solutions at room temperature. The oxide electrodes were characterized by cyclic voltammetry. Paraquat electrochemical oxidation was carried out by electrolysis at constant current and monitored by UV-vis absorbance measurements. Different anode/cathode pairs were used. After 1.5 h of electrolysis the highest removal (approximate to 79%), was obtained with the electrode pair Pt/steel followed by Co2FeO4/Pt (approximate to 55%), corresponding to the paraquat oxidation by a conversion mechanism. Removals of approximate to 64% were obtained with Co2FeO4 /Co2FeO4 after 3 h of electrolysis. Mass spectrometry analysis indicates that the main intermediate oxidation products were monopyridone and dipyridone derivatives. (C) 2015 Elsevier Ltd. All rights reserved.