Enhanced photocatalytic reduction of Cr(VI) under visible light a magnetically separable TiO\(_{2}\)-Fe/Fe\(_{3}\)O\(_{4}\) photocatalyst prepared from iron rusty waste

This research deals with enhancing the visible activity and generating the magnetic property of TiO2 by Fe doping and Fe3O4 impregnation respectively, using rusty iron waste as Fe source. The prepared TiO2-Fe/Fe3O4 photocatalysts were characterized by SR-UV/Visible, FTIR, XRD, and SEM-EDX instruments. The resulting photocatalysts are responsive to visible light and can be separated magnetically and used for photoreduction of Cr (VI) ions. In the photoreduction of Cr(VI) over TiO2-Fe/Fe3O4 photo-catalysts with various amounts of Fe dopant and alteration of Fe3O4 fraction, the photocatalyst mass, irradiation time, and solution pH were optimized. The research results assign that doping Fe to TiO2 photo-catalysts can decrease the band gap energy (Eg) consequently improving its activity under visible irradiation. Furthermore, the magnetization of TiO2-Fe allows it to be separated practically and effectively. The best detachable and the most active photocatalyst is shown by TiO2-Fe/Fe3O4 having a Ti/Fe mole ratio of 1:0.05 and Fe3O4 fraction of 50.00%. The highest photo-reduction of Cr(VI) 10 mg∙L‒1 in 100 mL solution, 92.5%, can be achieved by applying 0.2 g of the photocatalyst mass, solution pH 3, in 90 min of reaction time under visible light.