Electrochemical oxidation of Methyl Red using Ti/Ru0.3Ti0.7O2 and Ti/Pt anodes

The present study was motivated by a report by Martínez-Huitle et al. in 2005, on the electrochemical oxidation of oxalic acid at a Pt anode in the presence of halide ions in alkaline medium. Addition of halide salts increased the mineralization rate in the order: control < NaCl < NaBr < NaF. Therefore, in this work, the direct and indirect oxidations of an organic model substrate (Methyl Red, MR) using Ti/Ru0.3Ti0.7O2 and Ti/Pt anodes were investigated. Galvanostatic electrolyses of dye solutions led to complete decoloration and total organic carbon (TOC) removal at different operating conditions (current density (j) and temperature). The influence of these parameters was examined, in order to compare the effect of active chlorine and addition of different NaCl concentrations to the dyes solutions during the mediated electrochemical oxidation of MR. Byproducts generated during the direct and indirect MR electrochemical oxidation were identified on the basis of GC–MS results. Chlorinated compounds were produced during mediated electrochemical oxidation, but these were completely eliminated in the final of the process; confirming that this treatment processes can be a suitable alternative for depuration effluents. The findings presented herein are described and discussed in the light of the existing literature data.

► The direct and indirect oxidations of dye using Ti/Ru0.3Ti0.7O2 and Ti/Pt anodes were studied. ► The mechanism of direct and indirect electro-oxidation of Methyl Red was discussed. ► It was studied the oxidation of dye by active chlorine electrogenerated. ► It was available the influence of electrodic material in intermediated of Methyl Red oxidation.