MVX TITANIUM DIOXIDE
Titanium dioxide (TiO2) is a well-known material and has a lot of applications in daily life. For reasons of its high refractive index the principal use of TiO2 is as a whitening and opacifying agent (e.g. paints, ink, cosmetics, toothpaste, paper and food or food packaging). Furthermore, it is used in sunscreens as an UV-filter. Finally, being a photocatalyst TiO2 has different applications and used in self-cleaning surfaces, water and air purification or as an antimicrobial coating.
The nucleus of a TiO2-atom is surrounded by electrons travelling across special paths or orbits. The electron orbit furthest from the nucleus is the ‘valence band’. The band outside the valence band is referred to as the ‘conduction band’. When the energy of light is absorbed by TiO2 electrons jump from the valence band to the conduction band. Creating ‘positive holes’ left behind by the electrons (valence band) and ‘excited electrons’ (conduction band). These positive holes have a strong oxidative decomposing power as the excited electrons have reducing power. Water on the surface of TiO2 is oxidized by its positive holes forming hydroxyl radicals (OH·). Also, oxygen from the air is reduced by the excited electrons resulting in the production of superoxide anions (O2-). Both, the superoxide anions and hydroxyl radicals decompose gaseous pollutants, aqueous pollutants and liquid and solid films. Furthermore, it has an antimicrobial effect (bactericidal, virucidal, fungicidal). Most of these pollutants or microorganisms can be completely decomposed into CO2 and H2O.