Abstract
The electro-Fenton (EF) process is a type of electrochemical oxidation process; ·OH radicals are generated on the cathode using electricity and decolorize dye wastewaters. Most studies on EF systems in the past have focused on the operating parameters of this process. In recent years, the influence of electrode performance on the EF process has begun to receive more attention. In this study, direct nitridation was used to prepare titanium nitride powders, which were thereafter coated on an SUS304 stainless steel substrate. The performance of this system in the treatment of rhodamine B dye wastewaters via the EF process was investigated. The experimental methods used in this work include: (1) scanning electron microscopy (SEM); (2) X-ray diffraction (XRD); (3) electrochemical Tafel curves; (4) linear sweep voltammetry (LSV); (5) and cyclic voltammetry (CV). It was shown that high-purity TiN can be formed at nitriding temperatures above 900 °C, and the strength of the (111) crystal plane increases with the increase in nitriding temperature; the TiN coating effectively activates the reactive surface of the electrode owing to its porous structure. In terms of corrosion resistance, the corrosion potential and corrosion current of the TiN 1000 °C/SUS304 electrode were 116.94 mV and 205 nA/cm2, respectively, and the coating had a coating porosity of 0.89 × 10−7. As compared with SUS304 stainless steel, the TiN 1000 °C/SUS304 composite electrode had a significantly greater degree of corrosion resistance and exhibited higher redox activity in LSV tests. This composite electrode could achieve a decolorization rate of 49.86% after 30 min, and 94.46% after 120 min. In summary, the TiN 1000 °C/SUS304 composite electrode is very stable and has excellent decolorization efficacy in the EF process. Our findings will serve as a useful reference for future studies on EF electrodes.
Highlights
The environmental hazards associated with industrial pollution and energy production have always been treated as issues of utmost importance by countries around the world
The equation used for calculating the decolorization rate is shown in Equation (6); C0 is the initial concentration of rhodamine B (RhB), C is the concentration of RhB after the reaction
The nitriding temperature determines the degree of TiO2 nitrification and the formation of Titanium nitride (TiN)
Summary
The environmental hazards associated with industrial pollution and energy production have always been treated as issues of utmost importance by countries around the world. Stainless steel can be used as EF electrodes as they are conductive and amendable to processing, but further improvement is required in terms of corrosion resistance and specific surface area. Liu et al [18] noted that TiN has high levels of electrochemical stability, excellent conductivity, and superb corrosion resistance, and it can be used to improve the activity and durability of carbon nanotubes (CNTs)/Pt catalysts in direct methanol fuel cells. The cathode for the EF system being used in this work must possess high corrosion resistance, excellent conductivity, large reactive surface area, and the ability to produce H2O2; TiN has the potential to satisfy these requirements. We thereafter investigated the performance of this electrode in the treatment of rhodamine B (RhB) wastewaters
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