Binder-free immobilization of TiO₂ photocatalyst on steel mesh via electrospraying and hot-pressing and its application for organic micropollutant removal and disinfection

An immobilized photocatalyst was prepared by thermally treating TiO₂-coated steel mesh (TiO₂-IS) in a laboratory hot-press with no binder. TiO₂ coating was performed by electrospraying a 1 mg/mL methanol dispersion of Evonik P25 powder. The thermal treatment conditions at 350 °C, 100 Mpa, and 1 h were found to be the optimum conditions. Scanning electron microscopic images displayed a robust and adherent TiO₂ layer on steel mesh. X-ray photoelectron spectroscopy and elemental mapping studies confirmed that the Fe₃O₄ interface formed during thermal treatment strongly bound the TiO₂ on steel mesh. The XRD patterns of TiO₂-IS indicated the preservation of crystalline structure of Evonik P25 (anatase and rutile mixture) and the existence of iron oxide interface. Under UVA irradiation, 10 μM of methylene blue was completely decolorized within 40 min using an immobilized photocatalyst with 2.120 mg of TiO₂ per 2.5 × 5.0 cm² and showed stable efficacy in 25 consecutive photocatalytic runs. Furthermore, this sample degraded the organic micropollutants (e.g., pharmaceuticals) such as carbamazepine, ranitidine, acetaminophen, and trimethoprim at the rates of 0.041, 0.165, 0.089, and 0.079 min⁻¹, respectively. Under UVA irradiation, it exhibited high photocatalytic disinfection activity for Escherichia coli and MS2 coliphage.