Iron (III)-doped PbO₂ and its application as electrocatalyst for decomposition of phthalocyanine dye

The textile industry contributes significantly to environmental pollution through dyeing and finishing processes that release dyes into wastewater. Even small amounts of dyes can have harmful effects and cause negative impacts. These effluents have carcinogenic, toxic, and teratogenic properties and can take a long time to be naturally degraded through photo/bio-degradation processes. This work investigates degradation of Reactive Blue 21 (RB21) phthalocyanine dye using anodic oxidation process with PbO₂ anode doped with iron III (0.1 M) (marked as Ti/PbO₂-0.1Fe) and compared with pure PbO₂. Ti/PbO₂ films with and without doping were successfully prepared by electrodeposition technology on Ti substrates. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS) was used to characterize the electrode morphology. Also, linear scanning voltammetry (LSV) and cyclic voltammetry (CV) tests were conducted to investigate the electrochemical response of these electrodes. The influence of operational variables on the mineralization efficiency was studied as a function of pH, temperature, and current density. Doping Ti/PbO₂ with Fe³⁺ (0.1 M) could reduce the particle to a smaller dimension and slightly increase the oxygen evolution potential (OEP). A large anodic peak was found for both electrodes prepared in the CV test, indicating that oxidation of the RB21 dye was easily achieved on the surface of the prepared anodes. No significant effect of initial pH on the mineralization of RB21 was observed. RB21 decolorization was more rapid at room temperature and increases with increasing current density. A possible degradation pathway for the anodic oxidation of RB21 in aqueous solution is proposed based on the identified reaction products. In general, it can be said that from the findings it was observed that the Ti/PbO₂ and Ti/PbO₂-0.1Fe electrodes show good performance on RB21 degradation. However, it was noted that the Ti/PbO₂ electrode tends to deteriorate over time and exhibits poor substrate adhesion, while the Ti/PbO₂-0.1Fe electrode displays superior substrate adhesion and stability.