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

Abstract

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 degrees 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 mu M of methylene blue was completely decolorized within 40 min using an immobilized photocatalyst with 2.120 mg of TiO2 per 2.5 x 5.0 cm(2) 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 coil and MS2 coliphage.