Synthesis, characterization and photocatalytic activity of Al₂O₃-TiO₂ based composites

Abstract

The synthesis, characterization and photocatalytic performance of non-traditional Al₂O₃-TiO₂-based photocatalysts is reported. Al₂O₃-TiO₂ support was loaded with various fractions of CuO and ZrO₂. A sound agreement was observed between the bandgaps of synthesized powders measured by UV-Visible diffuse reflectance spectroscopy (DRS) in the solid phase and UV-Visible spectroscopy in the aqueous medium. X-ray diffraction (XRD) analysis revealed the composite nature of the catalysts with the retention of individual identity of each component. The average crystallite size of the individual component was found to be in the range of 20 to 40 nm. Scanning electron microscopy (SEM) analysis authenticated the presence of CuO and ZrO₂ at the surface of Al₂O₃-TiO₂ support, while Rutherford Back Scattering Spectroscopy (RBS) confirmed the quantity of the modifiers as per theoretical calculations. The composites showed an enhanced photocatalytic activity in sunlight compared to Al₂O₃-TiO₂ for the degradation of dyes. Efforts were made to elucidate the enhanced sunlight response of the synthesized composite catalysts compared to Al₂O₃-TiO₂. As monitored by ion chromatography (IC), the synthesized photocatalysts completely mineralized the dyes leaving behind inorganic ions in solution. The kinetics of photocatalytic degradation of dyes was evaluated for optimum correlation with the existing models. The stability of the photocatalysts against the photo-corrosion was monitored by analyzing the samples for respective metals in solution after sunlight exposure.

Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file.

Keywords:

• Dyes
• composites
• photocatalysis
• photocorrosion
• sunlight

Acknowledgments

Iqbal M.I. Ismail, A. Hameed and M. Aslam are thankful to CEE S., KAU (Project no. 1/W/1433) and Ministry of Higher Education, KSA, for support. M.A. Gondal is thankful to KFUPM for supporting this work.