Fabrication of high performance Ti/SnO2-Nb2O5 electrodes for electrochemical textile wastewater treatment

Abstract

Textile wastewater contains many organic compounds and colors that affect aquatic life and human health when discharged into the environment. High coloration due to excess dyes entering the wastewater causes coloration to the receiving water stream, affects the photosynthesis process of aquatic species, and adversely affects the landscape. SnO2-based electrodes have been extensively used in electrochemical water treatment, but their low durability decreases the pollutant treatment ability. Therefore, it is necessary to add another stable oxide to improve the performance and stability of SnO2 electrodes. This study aims to fabricate Ti/SnO2-Nb2O5 electrodes for the textile wastewater treatment using the electrochemical oxidation method. Different molar ratios of SnO2:Nb2O5 coating were prepared using the sol-gel method and then coated on the Ti substrates for calcination in 60 min at 500 °C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET), and cyclic voltammetry (CV) were used to determine the surface and electrochemical properties of Ti/SnO2-Nb2O5 electrodes. The SEM images show that SnO2-Nb2O5 electrode surfaces have the appearance of typical cracking structures of mixed metal oxides electrodes. The XRD spectrum show the SnO2 peaks of facet (110), (101), (200), (301), (321) and Nb2O5 peaks of facet (001), (002), (100), (101), (102) on Ti substrates. Furthermore, the specific surface area of the Ti/SnO2-Nb2O5 electrode ranges from 37.354 m2/g (SnO2:Nb2O5 = 9:1) to 71.885 m2/g (SnO2:Nb2O5 = 1:9). The electrochemical properties of SnO2:Nb2O5 electrodes showed high oxygen, chlorine evolution potential and high organic pollutant degradation in textile wastewater with COD removal at 83 %, decolorization at 74 % and the generation of many free radicals such as HO•, H2O2, O3, Cl2. The results demonstrate that the Ti/SnO2-Nb2O5 electrode with the mole ratio of 3:7 is the best in textile wastewater treatment with the longest service life (39 h).