Visible light-driven photocatalytic removal of water pollutants by a carbon-modified magnetically active ternary TiO2 (Fe3O4/carbon/TiO2) composite

Abstract

Remediation of water pollutants from water using various techniques is a highly focused area in recent years, and visible light-aided photocatalysis is an emerging technique in this field. Although semiconductor materials such as TiO₂ or ZnO are commonly used catalysts, they have certain important limitations such as activation only under UV light, stability for reuse, and difficulties in the separation from treated waters. In this study, we attempt to prepare a TiO₂-based hybrid that could be active under visible light and separable from the reaction medium by the magnetic method. Among various water pollutants, plastic industry leach-outs have been a major concern in recent years. Hence, bisphenol A (BPA) was chosen as a model pollutant in this study, which is also a known leaching chemical from PET. The magnetic composite, Fe₃O₄–carbon, was prepared hydrothermally using D-gluconic acid as a carbon source, and then modified wet chemically to obtain the TiO₂-containing composite. The degradation of BPA offered up to 95% (15 ppm BPA, 1 g L⁻¹ catalyst dose) upon irradiation under visible light with a significant rate constant of 1.3 × 10⁻² min⁻¹. The photodegraded intermediates formed in the reaction were traced using the GC-MS technique. The importance of the carbon component in the material was studied in detail by thermal treatment at different temperatures, varying the amount of the carbon content and carbon layer, comparison with the physical mixture, etc.