Feasible oxidation of 17β-estradiol using persulfate activated by Bi2WO6/Fe3O4 under visible light irradiation

Bismuth tungstate magnetic composites (BTMCs, Bi2WO6/Fe3O4) were synthesized by a template-free hydrothermal process. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and using a vibrating sample magnetometer (VSM). The photocatalytic activities of BTMCs were evaluated to degrade 17 beta-estradiol (E2) under visible light irradiation in the presence of persulfate (PS). It was found that PS could enhance the photocatalytic efficiency of BTMCs and could be activated to promote the removal of E2 with sulfate and hydroxyl radicals. The persulfate concentration and catalyst dosage play important roles on the degradation of E2, which is significant in a wide pH range (3.0-9.0). Recycling experiments demonstrated that BTMCs could maintain strong photo-catalytic stability over five cycles. Moreover, a mechanism is proposed that contains adsorption and electron transfer for the interactions between BTMCs and PS under visible light with 9 intermediate products identified. This study provides a feasible way to degrade organic pollutants in water using BTMCs with PS under solar light.