Photocatalytic activity of Fe/Ti-based compounds obtained from ferro-titaniferous mineral sands via a simple soft chemistry route

Abstract

Fe/Ti-based compounds were synthesized from ferro-titaniferous mineral sands using aqueous oxalic acid under subcritical water (sCW) conditions (135°C/50 bar/4 h) and their photocatalytic activity was evaluated against methylene blue or caffeine under UV-A and visible radiation. The X-ray diffraction and Raman spectroscopy analyses revealed that the as-synthetized compounds were mainly comprised of ferrous oxalate, followed by titanium dioxide. This proved the complete transformation of the mineral precursor within 4 h using oxalic acid/sCW as the reaction medium. The photocatalytic studies showed that methylene blue and caffeine were photodegraded under UV-A and visible radiation by the as-synthesized Fe/Ti-based compounds. Methylene blue removal was up to 92.8 and 97.4% after 6 hours under UV-A or visible irradiation, respectively. Caffeine removal, however, reached 69.3 and 59.6% after 16 h of exposure to UV-A and visible light, respectively. The as-synthesized compounds can be potentially used as a ferrous-based catalyst in heterogeneous photocatalysis for decontamination of water systems from organic pollutants.