Magnetically recoverable TiO₂-WO₃ photocatalyst to oxidize bisphenol A from model wastewater under simulated solar light

A novel magnetically recoverable, visible light active TiO₂-WO₃ composite (Fe₃O₄@SiO₂@TiO₂-WO₃) was prepared to enable the photocatalyst recovery after the degradation of bisphenol A (BPA) under simulated solar light. For comparison, the photocatalytic activity of other materials such as non-magnetic TiO₂-WO₃, Fe₃O₄@SiO₂@TiO₂, TiO₂, and the commercial TiO₂ P25 was also evaluated under the studied experimental conditions. The structure and morphology of the synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and electron dispersion spectroscopy (EDS). Moreover, Brunauer-Emmett-Teller (BET) surface area and magnetic properties of the samples were determined. The Fe₃O₄@SiO₂@TiO₂-WO₃ and TiO₂-WO₃ led to a BPA degradation of 17.50 and 27.92 %, respectively, after 2 h of the simulated solar light irradiation. Even though their activity was lower than that of P25, which degraded completely BPA after 1 h, our catalysts were magnetically separable for their further reuse in the treatment. Furthermore, the influence of the water matrix in the photocatalytic activity of the samples was studied in municipal wastewater. Finally, the identification of reaction intermediates was performed and a possible BPA degradation pathway was proposed to provide a better understanding of the degradation process. [Figure not available: see fulltext.].