Preparation of TiO2/Silicalite-2@CoFe2O4 Magnetic Composites and Evaluation of their Photocatalytic Activity in Cr(VI) Removal

摘要

Magnetic nanoparticles of CoFe2O4 were synthesized by co-precipitation method. The magnetic material silicalite-2@CoFe2O4 (SC) was prepared by using tetrabutylammonium hydroxide as the template, tetraethoxysilane as the silica source and CoFe2O4 as the magnetic core. TiO2/silicalite-2@CoFe2O4 (TSC) magnetic photocatalyst was prepared by sol-gel technique using SC particles as the supporter and tetrabutyltitanate as the titanium source. The samples were characterized by X-ray diffraction, scanning electron microscopy, N-2 adsorption-desorption, Fourier transform infrared spectroscopy, and ultraviolet (UV)-visible diffuse reflectance spectra. The reduction of Cr(VI) in aqueous solution by UV/TSC process was studied under various operating conditions. The results demonstrate that the as-synthesized TSC has high photocatalytic activity due to the high dispensability of TiO2 provided by silicalite2@CoFe2O4. The removal of Cr(VI) reached 72.9 % by using 0.6 g/L of TSC under the optimum conditions within 180 min. The photocatalytic reduction of Cr(VI) by TSC followed the Langmuir-Hinshelwood kinetic model. At the end of the reaction, TSC could easily be recovered and could be reused without the significant loss of the catalytic activity.