Application of the synergistic Ti/SnO2–Sb–Cu anode and Ti/ZnO/CuO cathode in the electrochemical treatment of wastewater

Abstract

The current research mostly focused on the single working electrode of anode for the treatment of wastewater. Therefore, a low-cost dual-electrode system using Ti/SnO2–Sb–Cu (TSSC) as the anode and Ti/ZnO/CuO (TZC) as the cathode was constructed for the synergistic treatment of methylene blue dye wastewater. Electrochemical analyses of the TSSC electrode show an ultra-high oxygen evolution potential of 2.2 V, the greater stability and the excellent corrosion resistance when compared with the traditional Ti/SnO2–Sb (TSS) electrodes. Hydroxyl radicals (•OH) are thought to be the main oxidants in the degradation process, the results show that the content of •OH of the TZC cathode is 57 % higher than that of ordinary inert electrode. Due to the synergistic effect of the two electrodes, the color of methylene blue can be quickly removed by 99 % in 20 min, and the highest chemical oxygen demand (COD) removal rate can reach 79.5 %. The optimal operation conditions were a pH of 4, a current density of 20 mA cm−2 and an initial concentration of 50 mg L−1. Finally, the degradation pathway of MB was investigated using GC-MS technique and UV absorption spectroscopy. The results suggest that the large organic molecules are continuously cleaved to produce simple aromatic hydrocarbons, which are then destroyed to simple minor organic molecules, ultimately oxidized to CO2 and H2O. This investigation suggests a new idea for the design of an efficient and cost-effective double electrode for the electrocatalytic degradation of dye wastewater.