Inexpensive synthesis of a high-performance Fe₃O₄-SiO₂-TiO₂ photocatalyst: Magnetic recovery and reuse

Abstract

A sol-gel technique has been developed for the synthesis of a magnetite-silica-titania (Fe₃O₄-SiO₂-TiO₂) tertiary nanocomposite with improved photocatalytic properties based on the use of inexpensive titania and silica precursors. The exceptional photocatalytic activity of the resulting materials was demonstrated by using them to photocatalyze the degradation of methylene blue solution. The best formulation achieved 98% methylene blue degradation. An interesting feature of the present work was the ability to magnetically separate and reuse the catalyst. The efficiency of the catalyst remained high during two reuses. The synthesized nanomaterials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, ultra-violet-visible spectroscopy, diffuse reflectance spectroscopy, and thermogravimetric analysis. XRD analysis revealed the formation of multicrystalline systems of cubic magnetite and anatase titania crystals. SEM and TEM characterization revealed well-developed and homogeneously dispersed particles of size less than 15 nm. FTIR spectra confirmed the chemical interaction of titania and silica. It was further noticed that the optical properties of the prepared materials were dependent on the relative contents of their constituent metal oxides.

Key words： sol-gel; photocatalysis; magnetic recovery; TiO₂; Fe₃O₄; SiO₂

Acknowledgements

This work was supported by the Human Resources Development Program (No. 20154030200680) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Trade, Industry and Energy. Authors are also thankful to HEC (Higher education Commission) of Pakistan for providing financial aids.

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