Dispersion of TiO₂ particles and preparation of SiO₂ coating layers on the surfaces of TiO₂

Abstract

Fine TiO₂ has been widely used as a white pigment, but the aggregation of TiO₂ particles related to the high specific surface area makes it a challenge to modify its surface. In this paper, NaOH and Na₂SiO₃ were adopted as regulators for the pH of TiO₂ aqueous dispersion. It was discovered that when the pH is 12, the TiO₂ particles have the maximum zeta potential and the repulsive force between two TiO₂ particles is also at the maximum, which is favourable for the dispersion of TiO₂. In terms of the modifying the surface, it was proved that a continuous and compact film of hydrous silica on the surface of TiO₂ particles is produced by coprecipitation of Na₂SiO₃ and H₂SO₄ when the TiO₂ particles are adequately dispersed by ultrasound at pH 12. Furthermore, it was found that the morphology of SiO₂ is different when Na₂SiO₃ and H₂SO₄ solutions are added in different ways.

Keywords:

• Titanium dioxide
• Coating
• Silica
• Dispersion
• Interface