Comparative electrochemical oxidation of methyl orange azo dye using Ti/Ir-Pb, Ti/Ir-Sn, Ti/Ru-Pb, Ti/Pt-Pd and Ti/RuO2 anodes

The relative oxidation power of dimensionally stable anodes, namely Ti/Ir-Pb, Ti/Ir-Sn, Ti/Ru-Pb, Ti/Pt-Pd and Ti/RuO2, has been determined from the anodic oxidation (AO) treatment of 2 dm(3) of methyl orange azo dye solutions in 0.050 mol dm(-3) Na2SO4 of pH 7.0 at constant current density. The anodes were synthesized by the dip-coating method using the corresponding metallic chlorides in isopropanol/water and their morphology, surface roughness, crystallographic structure and composition were analyzed. A mixture of IrO2, Pb2O3 and Pb3O4 were the components in the outperforming Ti/Ir-Pb anode. The effect of current density, Na2SO4 concentration, and cathode nature on the decolorization of azo dye solutions by AO with Ti/RuO2 was examined. Under favorable conditions, 96%-98% color removal was achieved using Ti/Ir-Pb, Ti/Ir-Sn and Ti/Ru-Pb, with lower decolorization for Ti/Pt-Pd and Ti/RuO2 anodes. In all cases, a pseudo-first-order decolorization process was found. The oxidation ability of anodes rose in the order Ti/ RuO2