Comparative study of TiO2–Fe3O4 photocatalysts synthesized by conventional and microwave methods for metronidazole removal

Abstract

This study focused on a direct comparison of conventional hydrothermal and microwave treatment during the synthesis of TiO2–Fe3O4 photocatalyst, which is an effective catalyst for decomposing metronidazole. The photocatalyst underwent various characterization analyses, including X-ray diffraction, Raman spectroscopy, transmission electron microscopy, energy dispersive X-ray, and diffuse reflectance spectroscopy. The Raman spectroscopy analysis revealed that the materials obtained through the conventional hydrothermal treatment consisted of separate phases of anatase and magnetite. On the other hand, the materials synthesized using the microwave process showed a noticeable shift in the Eg band (143 cm−1) and its half-width towards higher wavenumbers. This shift is likely due to the introduction of Fe ions into the TiO2 lattice. Additionally, both conventional hydrothermal and microwave synthesis routes produced TiO2–Fe3O4 systems with superparamagnetic properties, as demonstrated by SQUID magnetic measurements. The TEM analysis revealed that the materials synthesized using the microwave process exhibited higher homogeneity, with no noticeable large aggregates observed. Finally, this work proposed a convenient LED photoreactor that effectively utilized the photo-oxidative properties of TiO2–Fe3O4 photocatalysts to remove metronidazole. Combining photoactive TiO2–Fe3O4 catalysts with an energy-efficient LED reactor resulted in a low electrical energy per order (EEO).