Study On Preparation And Photocatalytic Property Of TiO₂/SiO₂/(Mn_xZn_1-xFe₂O₄) And TiO₂/SiO₂/(the Compound Contained Mn Zn Ferrite) Magnetic Photocatalyst

The technique of titanium dioxide photocatalytic oxidation is a new kind of water treatment process with great potential application for protecting environment and it has become a hot research area now. As a photocatalyst, titanium dioxide has high catalyzed activity, excellent chemical stability, innocuity, low option to organics degradation and fully mineraling organics to CO2 and H2O. Although many researchs have proved to nanometer TiO₂ can decompose most organic pollutants into inorganic substances under UV irradiation, a problem which TiO₂ particles are difficult to be separated from the treated water restrict nanometer TiO₂ to cosmically apply. Many studies have been carried out to obtain magnetic titanium dioxide photocatalysts, in which the nanometer TiO₂ could be deposited onto the surface of mangnetic material such as Fe3O4,γ-Fe2O3,γ-Fe2O3 - SiO₂ and soon. But it is well known that Fe3O4,γ-Fe2O3 andγ-Fe2O3 are thermally instable, weak mangnetic property after been costed nanometer TiO₂ particles, quite easy to aggregate, and will transform into material without magnetic property at lower temperature.In this paper, Mn Zn ferrite (Mn_xZn_1-xFe₂O₄) was separately prepared by both coprecipitation -hydrothermal method under 90℃and sol-gel method synthesis, and the compound contained Mn Zn ferrite (Mn_xZn_1-xFe₂O₄) was obtained with sintered under different temperature. The Mn Zn ferrite (Mn_xZn_1-xFe₂O₄) and compound contained Mn Zn ferrite (Mn_xZn_1-xFe₂O₄) act as the magnetic core of composite photocatalyst, and then they were in turn coated with uniform layers of SiO₂ and amorphous titanium dioxide by the sol-gel and hydrothermal methods to get the photocatalysts of TiO₂/SiO₂/(Mn_xZn_1-xFe₂O₄) and TiO₂/SiO₂/( the compound contained Mn Zn ferrite). The particles of TiO₂/SiO₂/( the compound contained Mn Zn ferrite) with about 500nm has abviously structure of core-shell by the analysis of XRD and SEM and excellent stable. In addition VSM has showed that the magnetic property of products is well after the two steps of coating.Finally, it was found that the TiO₂/SiO₂/(Mn_xZn_1-xFe₂O₄) and TiO₂/SiO₂/( the compound contained Mn Zn ferrite) calcined at 450℃for 1h showed higher photocatalytic activity than that of pure TiO₂(150nm, Pangang group) by the photocatalytic degradations of Reactive Yellow 39, suggesting they be very promising .