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Electrooxidation of congo red at glassy carbon electrode in aqueous solution

Maurice O.Iwunze

Congo red is a symmetrical azo dye. Its exhibited color is pH-dependent and as such it has been used in chemistry as a pH indicator. This compound was electrolyzed in an aqueous solution at a Glassy Carbon Electrode (GCE) using 0.15MKCl as supporting electrolyte. Under the experimental conditions used in this study, Congo red was found to undergo a one-electron, diffusion-controlled and totally irreversible oxidation reaction. Its pertinent electrochemical parameters such as the number of electrons involved in the oxidation reaction, n, the apparent redox potential, Eï‚°ÂÂ’, the diffusion rate constant, D, the heterogeneous electron transfer rate constant, ks, and the current functionwere determined by cyclic voltammetric (CV) technique. These parameters were used in the determination of the reaction mechanism, which was EC2. The product formed after electrochemical oxidation was found to undergo a disproportionation reaction in accordance with literature observation.