PREPARATION OF γ -Fe2O3/SiO2/TiO2 UNDER THE LOW-TEMPERATURE AND THE PHOTO-CATALYTIC DEGRADATION OF SULFAMETHAZINE IN WATER

In this work, the magnetic gamma-Fe2O3/SiO2/TiO2 microspheres of core shell structure with convenient recyclability were prepared by using the ultrasonic-assisted modified Stober method and sol-gel approach, and the photo-activity of which was evaluated by through the photo-degradation of sulfamethazine in aqueous solution. Results suggested that the good superparamagnetic properties of gamma-Fe2O3/SiO2/TiO2 could be reserved by the formation of gamma-Fe2O3. The photo-degradation of sulfamethazine results demonstrated that the prepared gamma-Fe2O3/SiO2/TiO2 could provide the same high UV-photo-activity as that of P25 TiO2 because of their similar constitutes of anatase and rutile types. And the higher UV-photo-degradation rate for sulfamethazine of gamma-Fe2O3/SiO2/TiO2 than that of gamma-Fe2O3/TiO2 further demonstrated that the SiO2 interlining could not only block the contact of TiO2 shell and magnetic core gamma-Fe2O3, but also enhance the photo catalytic reactivity. Moreover, this easily recoverable gamma-Fe2O3/SiO2/TiO2 could be reused at least for five times without any appreciable reduction of photo-catalytic efficiency. In combination with HPLC/ESI-MS analysis and density functional theory, photo-degradation pathway of sulfamethazine had been speculated, and some key reaction processes as the hydroxyl oxide, ammonia oxidation, splitting decomposition and open loop reactions might have occurred during the photo-degradation of sulfamethazine.