Synthesis of titanium oxysulfate from ilmenite through hydrothermal, water leaching and sulfuric acid leaching routes

Abstract

Ilmenite (FeTiO3) is a mineral that abundantly available in nature. Its extraction process can provide titanium dioxide (TiO2) which is useful for various strategic applications including dye-sensitized solar cells, photocatalysts, and water splitting. To obtain TiO2, ilmenite has to be converted first into titanium oxysulfate (TiOSO4) precursor. This procedure needs optimization in processing parameters. Therefore, this research focuses on the preparing TiOSO4 precursor by ilmenite extraction. The process involved hydrothermal reaction with the time variation of 1 to 5 hours, water leaching at 40 oC and sulfuric acid leaching with two different concentration of 3 and 18 M at 90 oC. The residues from ilmenite extraction were characterized using scanning electron microscope (SEM), x-ray diffraction (XRD), x-ray fluorescence (XRF), while the filtrate was characterized using inductively coupled plasma-optical emission spectrometry (ICP-OES). The results showed that the ilmenite granules derived from hydrothermal process residue was still existed in the large grains. As the grain size became smaller after water and acid leaching, the effectiveness of the two treatments was noticeable. Upon hydrothermal process, increasing the reaction time from 1 to 5 hours decreased the concentration of titanium element in the filtrate from 400.39 to 18.31 ppm. However, the process of water and acid leaching successfully increased the titanium content in TiOSO4 from 4394.32 to 7868.82 ppm. It was also found that by increasing the sulfuric acid concentration up to 18 M has provided a more stable TiOSO4 solution for the purpose of TiO2 formation.