Photocatalytic degradation of methylene blue by 2 wt.% Fe doped TiO2 nanopowder under visible light irradiation

Abstract

In this paper, 2wt.% Fe doped TiO₂ nanopowder was prepared by a combination of sol-gel and mechanical alloying methods. The mechanical alloying of Fe powder with Ti(OH)₄ gel produced from the sol-gel method was used to produce Fe doped TiO₂ nanopowder. The synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and diffuse reflectance spectroscopy (DRS). The photocatalytic behavior of nanopowder was examined by the degradation of methylene blue (MB) under visible light irradiation. XRD result showed that the phase structure was a combination of anatase and rutile phases and the anatase percentage was considerably increased to 72.3 % by Fe doping. The FESEM results demonstrated that the average particle size of TiO₂ was decreased to 45 nm by Fe doping through ball milling. DRS results indicated the band gap of photocatalyst has shifted from 2.95 to 2.60 eV by Fe doping through ball milling. Photodegradation of MB was evaluated and the degradation rate was reached to 47% after 240 min under visible light irradiation. The photocatalytic performance of TiO₂ nanoparticles improved by doping Fe through mechanical milling. Degradation reaction conformed by the first-order reaction kinetic model. The recycled Fe doped TiO₂ nano-photocatalyst showed only a slight decrease of 7% in degradation rate after the third cycle.