Magnetically separable TiO2/SnO2/Fe3O4-based nanocomposite photocatalyst for organic dye removal under low-power ultraviolet-visible light irradiation

The photocatalytic removal of organic dyes from wastewater is typically accomplished using metal-doped semiconductor and binary/ternary nanocomposite powders, which feature a high specific surface area to volume ratio but are difficult to recover and reuse. Herein, a separable and reusable TiO2/SnO2/Fe3O4-based nanocomposite photocatalyst with the average particle size of 12.50 nm was synthesized using a simple sol-gel method. XRD, XAS and XPS analysis show that the synthesized photocatalyst mainly composed of anatase TiO2, SnO2, hematite, and magnetite. Its ability to promote the photodegradation of a model organic dye, reactive red 141 (RR141), was also evaluated under low-power UV-visible light irradiation (15-W LED light bulb). The synergy between adsorption and photocatalytic processes resulted in efficient (93 % of RR141 and 91 % of Tetracycline removed after 240 min) and rapid pseudo-first-order rate constant degradation in comparison with commercial P25-TiO2 due to much narrower band gap energy, which were determined as 1.70 and 2.49 eV, allowing electron-hole pairs generation in the visible region. The nanocomposite could be easily recovered using an external magnet and reused at least five times with no significant drop in performance. Thus, this study paves the way for effective wastewater treatment under practically relevant conditions and contributes to the establishment of a greener society.