Photocatalytic degradation of tetrabromobisphenol A by a magnetically separable graphene–TiO2 composite photocatalyst: Mechanism and intermediates analysis

• Magnetically separable graphene–TiO2 composite photocatalyst was prepared for the first time.
• The composite photocatalysts show high activity for tetrabromobisphenol A degradation.
• The effect of graphene amount on the photocatalytic activity was investigated.
• The intermediates of tetrabromobisphenol A in the photocatalytic process were analyzed.
• The photocatalytic degradation pathway of tetrabromobisphenol A was proposed.

A magnetically separable graphene–TiO2 (MG–TiO2) hybrid photocatalyst was successfully prepared by a one step method. Namely, simultaneous reduction of graphene oxide and deposition of TiO2 on the graphene was occurred in one single process. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) analysis, X-ray photoelectron spectroscopy (XPS) and The Brunauer–Emmett–Teller (BET) analysis. The photocatalytic activity of the obtained samples was measured by the decomposition of methylene blue (MB) and tetrabromobisphenol A (TBBPA, a brominated flame retardant) under UV light irradiation. The results showed that MG–TiO2 exhibited much higher photocatalytic performance than that of bare TiO2. The enhanced activity can be ascribed to the incorporation of graphene. In addition, the MG–TiO2 with MG content of 3% exhibited the highest activity towards MB and TBBPA degradation. The intermediates of TBBPA in the photocatalytic degradation process were analyzed by LC–MS. On the basis of the identified intermediates, the photocatalytic degradation pathway of TBBPA was proposed. Furthermore, the recyclable ability of the samples was also studied and the results showed that the samples exhibited high stability.