A comparison of electrolysis and Fenton reaction pretreatment methods for dye wastewater

Abstract

Electrochemical oxidation is an effective pretreatment method for dye wastewater. In this study, the pretreatment of actual dye wastewater by electrochemical oxidation using a Ti/PbO₂ anode and a Ti/RuO₂ anode were compared with the data obtained by the Fenton reaction. The optimum pH, Fe²⁺ dosage, and H₂O₂ dosage were 3.0, 400 mg/L, and 480 mg/L, respectively, for the Fenton process. The chemical oxygen demand (COD) was reduced by 26.5% by the Fenton reaction at the optimum conditions. Various densities (20–30 mA/cm²) were applied in the electrolysis process and the appropriate current density was 20 mA/cm². The reduction in the COD and color removal increased with time, and pH fluctuations did not have a significant effect on the process. The electrolysis process was more efficient for decolorization than the Fenton process in the presence of chlorine. Among the three methods, electrocatalytic oxidation using a Ti/PbO₂ anode was the most efficient method for COD removal and decolorization. At 90 min, the COD decreased by 25% and color removal was 95% with a high current efficiency of 62%.The cost of this process was 0.308 USD per kilogram reduction in the COD.

Keywords:

• Fenton reaction
• Electrolysis
• Ti/RuO₂ electrode
• Ti/PbO₂ electrode

Acknowledgments

This work was financially supported by the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China (No. 2011BAE07B09).