Photocatalytic Oxidation of Rhodamine 6G Dye Using Magnetic TiO2@Fe3O4/FeZSM-5

M. Dükkancı

Abstract
Efficient decolorization of Rhodamine 6G dye (Rh 6G) using magnetic TiO2@Fe3O4/FeZSM-5 photocatalyst was carried out in a batch reactor equipped with two visible lights (high-pressure Na lamps). The photocatalyst was synthesized and characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, diffuse reflectance spectroscopy and vibrating sample magnetometry. The effects of initial Rh 6G concentration, catalyst loading, and pH were investigated on photocatalytic oxidation of Rh 6G. Maximum decolorization of 98.2 % was found at optimum conditions of 20 ppm Rh 6G, 1 g L–1 of catalyst, and pH of 13.04. Central composite design was used for the optimization of photocatalytic degradation of Rh 6G. Predicted decolorization efficiencies were found to be in good agreement with experimental values with high regression coefficient of 98.8 %. In addition to color removal, the toxicity of the Rh 6G aqueous solution was significantly reduced after photocatalytic oxidation. Small reduction of activity (from 34.6 % to 30.5 %) showed the stability of the catalyst after three consecutive runs. Due to the magnetic property of the catalyst, it could be removed from the solution with the help of external magnetic field. This prevents the loss of catalyst and reduces the extra separation cost, which is desired in industrial or large-scale applications.

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Keywords
magnetic photocatalyst, photocatalytic oxidation, Rhodamine 6G, TiO2@Fe3O4/FeZSM-5, toxicity