Indirect Electrochemical Oxidation of Dye Wastewater Containing Acid Orange 7 Using Ti/RuO2-Pt Electrode

Indirect electrochemical oxidation has been an alternative method for the decontamination of dye wastewater. In this study, the Ti/RuO2-Pt anode was used to remove the Acid Orange 7 (AO7) from the synthetic dye wastewater. The influence of operating parameters, including NaCl dosage, current density, initial concentration and pH, on the removal of AO7 was studied. The performance of Ti/RuO2-Pt anode for decomposition of dye and long time service was also investigated. The results show that, in the presence of chloride ion, the electrogenerated active chlorine played an important role in dye wastewater treatment. The pH of the solution had a significant effect on the existing form of active chlorine, and the optimum pH range was from weakly acidic to neutral. The changes of UV-Vis spectral, HPLC chromatogram and TOC during electrolysis indicated that, the dyestuff of AO7 could be decomposed and mineralized efficiently by electrolyzing with Ti/RuO2-Pt anode. All AO7 and 79.48% of TOC were removed within 4 hours in the presence of 0.001 M NaCl at a current density of 10 mA/cm2 and pH 6.8. The Ti/RuO2-Pt electrode had a relative long service life for dye wastewater treatment, and no obvious passivation was observed from the repeated test and surface characterization.