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

Abstract

Magnetic nanoparticles of CoFe 2 O 4 were synthesized by co-precipitation method. The magnetic material silicalite-2@CoFe 2 O 4 (SC) was prepared by using tetrabutylammonium hydroxide as the template, tetraethoxysilane as the silica source and CoFe 2 O 4 as the magnetic core. TiO 2 /silicalite-2@CoFe 2 O 4 (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 TiO 2 provided by silicalite2@CoFe 2 O 4 . 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.

Chromium removal from aqueous solution by a PEI-silica nanocomposite

“…For these reasons, studies on reducing the amount of chromium below the effluent water quality standard are very important issues. Various techniques have been studied to purify chromium-contaminated water, including ion exchange 9 , 10 , membrane processes 11 , electrodialysis 12 , precipitation 13 , bio-sorption 14 , photocatalytic degradation 15 , and adsorption 16 , 17 . In addition, Cr(III) can be easily precipitated from the aqueous phase by hydroxide or oxide foams.…”