Preparation and mechanism of TiO2-coated illite composite pigments

TiO2-coated illite composite pigments were prepared by hydrolyzing Ti(SO4)(2) on the surface of illite substrates and the products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), zeta potential analysis, and X-ray photoelectron spectroscopy (XPS), respectively. Density functional theory calculations of the energetic stability and electronic structure of illite, calcined illite, and TiO2-coated illite were used to analyze the chemical activity and bonding position between the anatase film and the illite particles. The results demonstrate that calcined illite is more suitable for metatitanic acid coating. Moreover, the surface of illite substrates is continuously coated with anatase and a chemical interaction could occur between the anatase film and the illite substrates. The whiteness, hiding power, and oil absorption value of the compound pigment are 95.73%, 97.55%, and 33.82 g/100 g, respectively. (C) 2014 Elsevier Ltd. All rights reserved.