Hypochlorite generation on Ru-Pt binary oxide for treatment of dye wastewater

Ruthenium-platinum binary oxides [(Ru+Pt)O_x] were coated on titanium substrates by thermal decomposition. The surface morphologies and elemental analyses of these electrodes were examined by means of scanning electron microscopy. The electrochemical behaviour was characterized by cyclic voltammetry (CV) and linear scanning voltammetry (LSV). The effects of electrolyte conditions on the current efficiency (CE) of hypochlorite production on binary (Ru+Pt)O_x electrodes and the treatment of a high salt-containing dye wastewater using this hypochlorite were also investigated. The highest CE for hypochlorite production occurred on the RP1 (20 mol % Pt in precursor) electrode. The major factors influencing CE for hypochlorite production were the electrolyte flow rate, current density and chloride ion (Cl^-) concentration. The RP1 electrode exhibited the best removal of organics and chromophoric groups in the dye wastewater. On this electrode, better removal of organics and chromophoric groups was obtained at 300 mA cm^-2. The colour of black-red dye wastewater became light yellow when a charge of 13.2 A h was passed while the COD of the wastewater decreased from 10500 to 1250 mg L^-1.