Enhanced Photocatalytic Performance of TiO₂@Er-HydroxyapatiteComposite for Cationic Dye and Drug Removal

Photocatalysis heterogeneous is an essential method for water treatment. In this study, a novel photocatalytic erbium-doped hydroxyapatite-decorated titanium dioxide (TiO₂@Er-Hap) was obtained using the sol–gel method and applied to remove ciprofloxacin (CIP) drug and methylene blue (MB) dye contaminants. The sample’s structural, physical, morphological, and photocatalytic properties were investigated. X-ray diffraction (XRD) confirmed the presence of the anatase phase in TiO₂@Er-Hap. The oxide nanoparticles were deposited on the Hap surface, and the proposed material presented a band gap energy of 3.33 eV. Furthermore, TiO₂@Er-Hap presented a larger surface area when compared with the material not decorated with the oxide. Photocatalysis tests performed under ultraviolet (UV) irradiation showed that TiO₂@Er-Hap removed MB dye (100%) and CIP (71.16%), despite low mineralization evidenced in TOC analysis. The irradiated pollutant solution after the photocatalysis process was nontoxic, as observed in the ecotoxic test, indicating that the photocatalytic worked. Inhibitor tests showed that the ^•OH radicals were the main species involved in the tests performed. The material demonstrated activity even after five consecutive cycles of use. Finally, the results suggest that TiO₂@Er-Hap is a suitable candidate for water decontamination via photocatalytic processes.