Synthesis of TiO2/SiO2@Fe3O4 magnetic microspheres and their properties of photocatalytic degradation dyestuff

The core-shell TiO 2 /SiO 2 @Fe 3 O 4 magnetic microspheres photocatalysts were synthesized by a simple sol–gel method. The magnetic microspheres possessed the higher BET surface area and the stronger superparamagnetism. The photocatalysts have an excellent photocatalytic performance for the photocatalytic oxidation degradation of Rhodamine and reusability. ► Core-shell TiO 2 /SiO 2 @Fe 3 O 4 magnetic microspheres photocatalysts were synthesized by a simple sol–gel method. ► The TiO 2 /SiO 2 @Fe 3 O 4 possessed the high BET surface area up to 495.3 m 2 g −1 and the strong superparamagnetism up to 48.6 emu/g. ► The TiO 2 /SiO 2 @Fe 3 O 4 photocatalysts showed the excellent photocatalytic performance for the photocatalytic oxidation degradation of Rhodamine and the reusability. The TiO 2 /SiO 2 @Fe 3 O 4 photocatalysts were synthesized via two steps. First, the SiO 2 @Fe 3 O 4 particles were synthesized using Fe 3 O 4 as the core and tetraethoxysilane (TEOS) as silica source. Second, the anatase TiO 2 was coated on the SiO 2 @Fe 3 O 4 particle surface using tetrabutyl titanate (TBOT) as titanium source. The synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption–desorption techniques and vibration sample magnetometer (VSM). The catalytic activity of TiO 2 /SiO 2 @Fe 3 O 4 catalysts for the photocatalytic degradation of Rhodamine (RhB) was evaluated under ultraviolet (UV) irradiation. The results indicated that the mean size of the 6%SiO 2 @Fe 3 O 4 particles was about 75–80 nm and thickness of the homogeneous SiO 2 layer was about 2–3 nm. The diameter of 50%TiO 2 /6%SiO 2 @Fe 3 O 4 microspheres was about 100 nm and thickness of the homogeneous anatase TiO 2 layer was about 8–10 nm. The saturation magnetization and specific surface area of 50%TiO 2 /6%SiO 2 @Fe 3 O 4 catalysts were 48.6 emu/g and 495.3 m 2 /g, respectively. The 50%TiO 2 /6%SiO 2 @Fe 3 O 4 microspheres exhibited the best photocatalytic performance. The conversion of RhB achieved up to 98.1% after 60 min UV irradiation, and the photocatalytic reaction apparent rate constant k a was 0.05288 min −1 . After used for 8 times, it also maintained high degradation rate and catalyst recovery.