Synthetic Ilmenite (FeTiO₃) Nanoparticles as a Heterogeneous Electro-Fenton Catalyst for the Degradation of Tetracycline in Wastewater

Explorations into the potential application of dual-metallic iron oxides, (FeXO₃), [where X is a transition metal] as heterogeneous electro-Fenton (HEF) catalysts have been of interest due to their enhanced catalytic activity. We thus present the synthesis and application of ilmenite (FeTiO₃) nanoparticles as a catalyst for HEF degradation of tetracycline (a pharmaceutical pollutant) in water. The ilmenite nanoparticles were characterized with electron microscopy, X-ray diffraction, Fourier transform IR spectroscopy, and BET analysis prior to their immobilization on a graphite felt (GF) cathode for HEF reactions. The effects of pH and catalyst loading on the HEF process were investigated. The extent of degradation was monitored with UV/vis spectroscopy and total organic carbon (TOC) measurements. The HEF system was robust over a wide pH range. Tetracycline in synthetic and real wastewater matrices was degraded, producing 61 and 40% TOC removal in 2 h, respectively. The comparative studies for the catalytic efficiencies of ilmenite (Ti-doped iron oxide) and commonly used HEF iron oxide catalysts, like magnetite, hematite, and goethite showed that synthetic ilmenite is an effective HEF catalyst for the degradation of organic pollutants in water. A slight Ti cocatalysis effect was observed in ilmenite nanoparticles based on the comparative HEF degradation results catalyzed by pristine iron oxide (hematite, Fe₂O₃) and ilmenite (iron-titanium oxide). Our results show that ilmenite can be reused up to six cycles without loss of activity, and therefore it is an effective HEF catalyst for wastewater treatment.