Application of TiO2-nanotubes/PbO2 as an anode for the electrochemical elimination of Acid Red 1 dye

In this study, galvanostatic electrolysis, through the use of the platinum supported on Ti (Ti/Pt) and Ti/TiO2-nanotubes/PbO2 anodes, was conducted in an electrochemical cell with 0.2 L of solution containing 100 mg dm−3 of the textile dye Acid Red 1 (AR1) using Na2SO4 as supporting electrolyte, applying 7.5 and 60 mA cm−2. From the voltammetric curves, it was possible to understand that Ti/TiO2-nanotubes/PbO2 electrode has high oxygen evolution overpotential than Ti/Pt anode. A direct electron transfer reaction is attained between the dye molecules and Ti/Pt surface, at lower currents. Conversely, the AR1 oxidation involves water decomposition intermediates, mainly ·OH radicals at Ti/TiO2-nanotubes/PbO2 anode. The electrolytic process was monitored by the UV–visible spectrometry and the chemical oxygen demand (COD). Results clearly show that Ti/TiO2-nanotubes/PbO2 anode performs better than Ti/TiO2 in removing ARI due to the electrosynthesis of strong oxidants on its surface (·OH and persulfates), achieving a higher oxidation rate, higher current efficiency, and less energy consumption than Ti/Pt electrode.