Production and characterization of manganese oxide-based electrodes for anodic oxidation of organic compounds

Preliminary results concerning the fabrication and use of manganese oxide thin film electrodes are presented. Different deposition techniques were employed and compared in order to obtain enhanced anodic oxidation of organic pollutants. In particular, manganese oxide films were produced by cathodic electrodeposition from aqueous KMnO4 solutions (Type-A), by anodic electrodeposition from aqueous MnSO4 solutions (Type-B) and by thermal decomposition from alcoholic solutions (Type-C). All the films were grown on titanium foil covered with a thermally deposited ruthenium oxide inter-layer to ensure good electrical contact. In addiction to characterization by cyclic voltammetry (CV), X-Ray diffraction (XRD), and profilometric measurements, the electrodes were tested for the treatment of aqueous solutions containing the azo dye Reactive Violet 5 (RV5), as a model organic pollutant. The azo-dye degradation, conducted under galvanostatic conditions in an undivided reactor, was evaluated by UV–Vis measurements and COD analysis. In the presence of small concentration of NaCl, all electrodes exhibited good decolorization and COD reduction capability. The type-B electrodes showed the best performances. The Type-C electrodes accounted for anodes less performant with negligible formation of active chlorine.