Synthesis of TiO2 nanopowders from red gypsum using EDTA as complexing agent

TiO2 white pigments were used in various applications due to their magnificent optical and electronic properties. In this paper TiO2 was recovered from red gypsum which is a waste generated at TiO2 production industry. The effect of time and temperature in sulphuric acid leaching processes was optimized. TiO2 powders were synthesized through thermal precipitation process with the presence of ethylenediaminetetraacetic acid as a complexing and purification agent. The obtained powders were characterized by X-ray diffraction, transmission electron microscope, UV–Vis spectroscopy and inductively coupled plasma optical emission spectroscopy. Experimental results show that powders in anatase form have a 3.2 eV band gap with a crystallite size 30–50 nm.