Preparations and photocatalytic degradation of methyl orange in water on magnetically separable Bi12TiO20 supported on nickel ferrite

A magnetically separable photocatalyst Bi12TiO20/SiO2/NiFe2O4 (BSN) with a typical ferromagnetic hysteresis was prepared by a simple process: the magnetic 200 wt% SiO2/NiFe2O4 (SN) dispersion prepared by a liquid catalytic phase transformation method and the visible-light-active photocatalyst Bi12TiO20 prepared by a simple coprecipitation processing were mixed, sonificated, dried, and calcined at 550 °C. The prepared photocatalyst showed high photocatalytic activity for the degradation of methyl orange in water under UV irradiation and visible-light irradiation (λ>400 nm), and it was easy to be separated from a slurry-type photoreactor under the application of an external magnetic field, being one of promising photocatalysts for wastewater treatment. Transmission electron microscope (TEM) and X-ray diffractometer (XRD) were used to characterize the structure of the photocatalyst, indicating that the magnetic SN particles adhered to the surface of the Bi12TiO20 congeries. SiO2 layer round the surface of NiFe2O4 nanoparticles prevented effectively the injection of charges from TiO2 particles to NiFe2O4, which gave rise to the increase in photocatalytic activity.