High Photocatalytic Efficiency of Al2O3-TiO2 Coatings on 304 Stainless Steel for Methylene Blue and Wastewater Degradation

Abstract

This work explores the novelty of achieving high photocatalytic efficiency and remarkable bactericidal activity with Al2O3-TiO2 coatings on perforated 304 stainless steel (SS) substrates, placed transversely along an airlift reactor of 0.980 L for wastewater treatment under visible light irradiation. The Al2O3-TiO2 coatings achieved methylene blue and total organic carbon (TOC) concentration reductions of 97.3 and 96.51%, respectively, in a wastewater sample with heterogeneous photocatalsis. The Al2O3-TiO2 coatings resulted in a 33.30% reduction in total and fecal coliforms and a remarkable 94.23% decrease in Salmonella spp. in the wastewater sample. XRD confirmed the TiO2 anatase–rutile phases and Al2O3 α-γ phases in the coating. The particle size distribution ranges from 100 to 500 nm, and the coating surface was homogeneous without cracks confirmed using SEM and AFM, respectively. The roughness and thickness of the coatings were 85 ± 5 nm and 250 ± 50 nm, respectively.