Preparation and characterization of Zr and Sn doped TiO₂ nanocomposite and photocatalytic activity in degradation of tetracycline

Abstract

The photocatalysts of Ti_0.9Zr_0.03Sn_0.07O₂, Ti_0.9Zr_0.05Sn_0.05O₂, and Ti_0.9Zr_0.07Sn_0.03O₂ nanocomposite were prepared using the sol–gel method. The structure of anatase–rutile for prepared photocatalysts was confirmed using X-ray diffraction patterns. The transmission electron microscope image indicated that the size of nanoparticles was in range of 30–80 nm. The elemental analysis of Ti_0.9Zr_0.05Sn_0.05O₂ nanocomposite was confirmed by energy dispersive X-ray analysis. The UV–vis absorbance spectra of nanocomposites showed a red-shift of band-gap energies of semiconductors vs. TiO₂ pure nanoparticles. The application of prepared nanophotocatalysts was studied in tetracycline photodegradation in aqueous samples. The complete degradation of pollutant in a photodegradation reaction with rate constant of 27.0 × 10⁻³ min⁻¹ was obtained at optimized conditions of 0.8 g/L of Ti_0.9Zr_0.05Sn_0.05O₂, pH 3, 20.0 mg/L of tetracycline and during time 180 min. The photocatalytic activity of nanoparticles was seen as Ti_0.9Zr_0.05Sn_0.05O₂ > Ti_0.9Zr_0.07Sn_0.03O₂> Ti_0.9Zr_0.03Sn_0.07O₂> TiO₂ that is related to the band-gap energies as 2.95 < 2.99 < 3.22 < 3.28 eV, respectively. The reusability of Ti_0.9Zr_0.05Sn_0.05O₂ photocatalyst was tested in four cycles of photodegradation process. The resistance against of photocorrosion is due to reproducibility of photocatalytic activity.

Keywords:

• Nanocomposite
• Photocatalyst
• TiO₂
• Tetracycline
• Photodegradation

Acknowledgments

We would like to thank the research committee of Malek-Ashtar University of Technology (MUT) and Islamic Azad University, Shahreza branch for supporting this work.