Photocatalytic removal of tetrabromobisphenol A by magnetically separable flower-like BiOBr/BiOI/Fe3O4 hybrid nanocomposites under visible-light irradiation.

A novel flower-like three-dimensional BiOBr/BiOI/Fe3O4 heterojunction photocatalyst was synthesized using a simple in situ co-precipitation method at room temperature. The hybrid composites were characterized by a couple of techniques including X-ray powder diffraction, scanning electron microscope, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, Brunauer-Emmett-Teller, X-ray photo-electron spectroscopy, photoluminescence technique, and vibrating sample magnetometer. Fe3O4 nanoparticles were perfectly loaded on the surface of BiOBr/BiOI microspheres. The recyclable magnetic BiOBr/BiOI/Fe3O4 was employed to degrade TBBPA under visible light irradiation. The optimal removal efficiency of the ternary BiOBr/BiOI/Fe3O4 (2:2:0.5) nanocomposite reached up to 98.5% for TBBPA in aqueous solution. The superior photocatalytic activity of BiOBr/BiOI/Fe3O4 was mainly ascribed to large surface area and appropriate energy gaps, resulting in the effective adsorption and separation of electrons-hole pairs. The photogenerated reactive species determined by free radicals trapping experiments revealed that the excellent catalytic activity was primarily driven by O2- radical. The photocatalytic degradation kinetics and a detailed mechanism were also proposed. Result demonstrated that the BiOBr/BiOI/Fe3O4 can be magnetically recycled, and maintain high photocatalytic activity after reuse over five cycles. It suggested that the synthesized material had a potentially promising application for TBBPA removal by photocatalytic degradation from wastewater.