[Low-temperature preparation of TiO2/PS/Fe3O4, and its photocatalytic activity and magnetic recovery].

This study reports the fabrication of magnetically responsive titania catalyst,which consisted of a magnetic core surrounded by a titania shell.The magnetic core(oleic acid-modified Fe3O4 nanoparticles) was modified with polystyrene as inert isolating layer.The magnetic photocatalyst was prepared at low temperature(90℃) and a neutral pH(about 7).The phase composition,morphology,surface properties and magnetic properties of the composite particles were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),fourier infrared photometer(FT-IR) and vibrating sample magnetometer(VSM).The photocatalytic activity of the samples were determined by degradation of phenol and their recovery characteristics were determined by a self-regulating magnetic recycling equipment.The results illustrated that the mean diameter of anatase titanium dioxide synthesized at low temperature was 2-5 nm,the catalyst TiO2/PS/Fe3O4[the molar ratio of the magnetic photocatalyst was n(TiO2)∶n(St)∶n(Fe3O4)=60∶2.5∶1] had the structural integrity of shell/shell/core,and titanium dioxide was loaded firmly on the PS/Fe3O4 surface.The photocatalytic degradation of phenol followed first-order reaction kinetics and the reaction rate constant K of the TiO2/PS/Fe3O4[n(TiO2)∶n(St)∶n(Fe3O4)=60∶2.5∶1] was 0.025 8,which was close to that of pure TiO2(K =0.026 2).After 5 times recycling,the K value reduced only by 0.003 4.The catalyst had a strong magnetic induction,and the average recovery rate reached 92%.The magnetic TiO2 photocatalyst prepared by this low-temperature hydrolysis method has a good application prospect.