Preparation Of Magnetic Iron Bismuth Composite And Its Visible Light Photocatalytic Properties

Bismuth ferrites, including of sillenite-type and perovskite-type compounds have been used as visible light photocatalysts in recent years because of its narrow band gap. However, the large catalyst dosage and low quantum efficiency are still drawbacks impeding the applications of bismuth ferrites in wastewater treatment. Much effort is needed to make further improvement of photocatalytic activity of bismuth ferrites.In this paper, a magnetically separable Bi2sFeO4o-graphene visible-light photocatalyst was prepared by hydrothermal method and characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), BET surface area measurements, Raman spectroscopy, X-ray photoelectron spectra(XPS) and magnetic hysteresis loop measurements. The XRD characterizations indicated that pure bismuth ferrite and bismuth ferrite-graphene composition obtained by the same hydrothermal method was BiFeO3and Bi25FeO40-graphene, respectively. The reduction of graphite oxide and the formation of Bi25FeO40were occurred simultaneously during the hydrothermal preparation, and were confirmed by Raman spectroscopy and XPS characterization analysis. In comparison with pure BiFeO3catalyst, the Bi25FeO40-graphene composite shows better magnetism, smaller particle size and larger specific surface areas.The photocatalytic Methyl Violet (MV) degradation demonstrated that the Bi25FeO40-graphene photocatalyst show prominently photocatalytic activity under visible light irradiation than that of pure BiFeO3or Bi25FeO40, owing to the promotion of MV adsorption and synergic effect of Bi25FeO40and graphene. In addition, the photocatalytic MV degradation process by Bi25FeO40-graphene followed the Langmuir-Hinshelwood model, indicating that surface reaction is a control step in photocatalytic reaction.Novel visible-light-induced Bi25FeO40-CN composite photocatalysts were synthesized via a mixing and heating method. And then characterized by XRD, SEM, BET surface area analysis, ultraviolet-visible diffuse reflection spectroscopy(UV-Vis DRS) and magnetic hysteresis loop measurements. The Bi25FeO40-CN composite photocatalyst shows better enhanced photocatalytic activity for the degradation of methylene blue (MB) under visible-light irradiation than that of Bi25FeO40due to the synergic effect of Bi25FeO40and CN. Additionally, the band gap of the Bi25FeO40-CN were reduced. The Bi25FeO40-CN composite was superparamagnetic, and could be readily recovered in an external magnetic field. Accordingly, the photocatalytic MB degradation over Bi25FeO40-CN followed the L-H model, indicative of an adsorption controlled reaction mechanism.