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

M Z Borhan,T Y Nee

doi:10.1007/s40097-014-0137-7

Abstract

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.

Highlights

Titanium dioxide, an important intermediate material, is widely used as a pigment in the manufacture of paints, paper, printing inks, rubber, floor covering, ceramics, pharmaceuticals and other areas of chemical industry paints, plastics, rubber, and paper industries
To study effect of leaching time on red gypsum by 80 % H2SO4 several experiments were performed at different reaction times ranging from 2 to 10 h
Even though there is no significant value of band gap energies, the absorption values between these two samples are different whereas calcined TiO2 shows higher absorption values of UV light which is useful to improve the photocatalytic performance

Summary

Introduction

An important intermediate material, is widely used as a pigment in the manufacture of paints, paper, printing inks, rubber, floor covering, ceramics, pharmaceuticals and other areas of chemical industry paints, plastics, rubber, and paper industries. There are two routes to produce titanium dioxide commercially which are through chlorination and sulphate process. Red gypsum is synthetic gypsum produced during titanium dioxide production to neutralize weak acid before release to the environment. J Nanostruct Chem (2015) 5:71–76 produce titanium dioxide pigment which generated weak acid which will be further treated with lime generating red gypsum [4]. It is important to remove Fe2O3 because at low content as low 100 ppm (10-6 wt%), it still gives TiO2 product yellow in colour which limited its photocatalytic application [3]. We utilize gypsum as a source of titanium via sulphate process to leach out titanium to the solution by optimizing two parameters which are temperature and reaction time. Water with a ratio 1:1 to a paste was added and stirred for 1.5 h at 90 °C for water leaching process

Methodology

Experimental procedure

Results and discussions

Conclusion