Preparation And Properties Of Magnetic-Nanocomposite Photocatalyst

With the development of the society, more and more people realized the closely connection between the environment and the human survival. Much effort has been paid recently in the environmental protection and contaminates control. TiO2 is exactly an excellent photocatalyst which finds important applications in these fields. Consequently, much interest has been evoked to the use of TiO2-based photocatalysts for the degradation of dyes in waste water. However, in practical applications, separation and recovery of TiO2 is still difficult to control and deal with, remaining an issue to be solved related to TiO2 functional materials. In this paper we try to incorporate magnetic iron oxide into TiO2 which provides a way to solve this problem.The main contents are summarized as follows:1. The well-dispersed magnetic Fe3O4 particles with a diameter of about 750 nm were prepared by solvothermal method. A superparamagnetic Fe3O4@SiO2@TiO2 photocatalyst have been successfully synthesized by coating a magnetic core with a dual layer of inert SiO2 and photoactive TiO2. Photoactive TiO2 shell is directly coated on Fe3O4@SiO2 core-shell spheres. Subsequent hydrothermal treatment improves the degree of crystallinity of TiO2. The introduction of an intermediate passive SiO2 layer between the Fe3O4 and TiO2 inhibited the direct electrical contact and hence prevented the photodissolution of the Fe3O4. The synthesized magnetic spheres show good photocatalytic activities in the degradation of methyl orange in the aqueous solution. This magnetic photocatalyst can be easily recovered by applying external magnetic field and have a high reusability.2. Fe3O4@TiO2 with core-shell structure was synthesized by direct deposition TiO2 onto a magnetic core, and the shell thickness could be easily tuned by varying the coating times. The results indicated that the prepared samples had excellent magnetism and perfect photocatalytic degradation activity of methyl orange. Remarkably, the photocatalyst still kept the decomposition efficiency up to 80% within 40 min even after being used for, five times. We also investigated the photocatalysis degradation mechanism and the degradation data were fitted to the pseudo first-order kinetic model.3. Fe3O4/TiO2-Co and Fe3O4/TiO2-Ni magnetic composites were successfully fabricated by a facile sol-gel method without template followed by calcinations. The results indicated that the prepared samples both have excellent magnetism and can be easily separated form reaction solution under an external magnetic field. The reusability of the composite photocatalytic samples was also tested and Fe3O4/TiO2-Ni showed better photocatalytic activity and reusability.