Fabrication of novel Ti/SnO2-Nb2O5 electrode in comparison with traditional doping metal oxides for electrochemical textile wastewater treatment

Abstract

Textile wastewater contains a number of hazardous and refractory organic contaminants, especially various dyes such as cibacron, cycafix, monozol, and procion, that contribute to the negative effects of textile wastewater on aquatic creatures due to a limitation of light penetration and the consumption of oxygen. The selection of electrode materials is always a primary concern for electrochemical methods. SnO2-based electrodes are now being pursued by researchers due to their low cost. As a result, adding another stable oxide is recommended to enhance the efficiency and stability of SnO2-based electrodes. This study aims to fabricate the Ti/SnO2-Nb2O5 electrodes in comparison with different traditional doping metal oxides, Ti/SnO2-Sb2O5, Ti/SnO2-TiO2, and Ti/SnO2-Ta2O5, using the sol–gel method for electrochemical textile wastewater treatment. The electrode’s surface morphologies, crystal structures, and electrochemical characteristics were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV), respectively. The SEM images illustrated that the surfaces of the four electrodes had typical cracking structures of mixed metal oxide electrodes. The presence of crystalline structures of SnO2, Sb2O5, Nb2O5, TiO2, and Ta2O5 on the electrodes was clearly determined. The direct experimental comparisons indicated that the Ti/SnO2-Nb2O5 electrode performed the best among the four oxides in the treatment of textile wastewater, with 87.0% and 84.3% efficiency in removing COD and color, respectively. A current density of 5.8 mA/cm 2 and a NaCl concentration of 2 g/L were found to be optimal operating conditions. The electrochemical properties of the fabricated electrodes showed a high oxygen evolution potential, stability, and the generation of numerous free radicals and oxidants such as •OH, H2O2, O3, and Cl2. These findings serve to inform the future selection of appropriate metal oxides to reinforce SnO2 electrodes for textile wastewater treatment.