Role of core diameter and silica content in photocatalytic activity of TiO2/SiO2/Fe3O4 composite

Magnetically separable TiO2/SiO2/Fe3O4 Composites of different core (Fe3O4) diameters and silica contents have been prepared by sol-gel technique for both silica and titania coatings. Energy dispersive X-ray fluorescence (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET surface area analysis and scanning electron microscope (SEM) have been used for characterization of prepared samples. Photocatalytic activity of the prepared samples has been investigated by photodegradation of methyl orange. Obtained results have shown that 25-45 mu m core diameter exhibits the maximum activity since it possesses a convenient surface area and light transmittance. Silica content has a significant effect on the activity of composite. Silica content of more than 10 wt% has reduced the catalyst activity because of the increase in particle diameter and reduction of surface area. (C) 2007 Elsevier Masson SAS. All rights reserved.