Textile dyes released to normal water reservoirs cause adverse effects and photocatalysis is a prominent method available to degrade dye molecules. Photocatalysts were synthesized using natural ilmenite as the raw material. Ilmenite sand was digested in hydrochloric acid. Sodium titanate solution obtained by treating the residue resulted after leaching in acid with NaOH and H2O2, was subjected to hydrothermal treatment followed by calcination at 800 °C to produce pure TiO2. The precipitate obtained by treating the acid leachate with NH3 annealed at 800 °C to produce TiO2/Fe2TiO5. FeSO4 was mixed with another portion of the acid leachate followed by the addition of NH3. Obtained residue was separately annealed at 450 °C and 800 °C to produce TiO2/Fe3O4 and TiO2/Fe2O3, respectively. Synthesized nanomaterials were characterized by X-ray diffractometry (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analyzer, scanning electron microscope (SEM), X-ray fluorescence spectroscopy (XRF), Diffuse reflectance UV-Visible spectroscopy (DRS). XRD patterns reveal the crystal nature of the nanomaterials which was confirmed by Raman spectroscopy. XPS exhibit the surface oxidation states, BET surface area analysis reveal the textural parameters and SEM images show the morphology of the nanomaterials. DRS analysis shows that the band gap energy resulted is lesser than the 3.0 eV which is the theoretical value of rutile due to the presence of V as revealed by XRF analysis. Photocatalytic activity of the synthesized nanomaterials was evaluated on the degradation of methylene blue upon exposure to visible light. The rate of photodegradation of methylene blue in the presence of TiO2/Fe2O3 (0.04355 min-1) is greater than TiO2/Fe2TiO5 (0.00609 min-1) and TiO2/Fe3O4 (0.00192 min-1). Type I band alignment in TiO2/Fe2O3 favour the charge separation, while type II band alignment in TiO2/Fe2TiO5 and TiO2/Fe3O4 cause charge recombination resulting in low photocatalytic activity.

Photocatalytic activity of titanium and iron based photocatalysts synthesized by natural ilmenite

ACS Spring 2022

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