Pigment grade TiO2 is manufactured to optimize the scattering of visible light which requires primary particles in the size range of approximately half the wave length of the visible light, whereas ultrafine TiO2 is engineered to have a primary particles in the nanoparticle size range, that is below 100 nm. Accordingly the scattering of visible light is significantly reduced and the TiO2 nanoparticles are transparent. Transparency and other properties related to this size provide different beneficial properties from those seen for the pigmentary product.
Ultrafine TiO2 has been used since the 1950s to reduce the environmental emissions of Nitrogen Oxides. It is used in “Selective Catalytic Reduction (SCR)” systems that convert the nitrogen oxides into harmless nitrogen and water. Commercial SCR systems are typically installed in large industrial boilers, combustion plants and stationary or automotive diesel engines.
The transparency and UV absorbance of ultrafine TiO2 allows for its’ effective use as a protective ingredient in sunscreens. It contributes to high sun protection factors (SPF) and has been used for many years to provide protection from the harmful ultraviolet radiation from the sun.
Another application uses the photocatalytic properties of ultrafine TiO2 to provide self-cleaning surfaces e.g. on glass and cement.
Although ultrafine TiO2 is comprised of primary particles in the nano size range, an inherent property of ultrafine TiO2 is that the primary particles are strongly bound or fused together by chemical bonds to form aggregates. These aggregates readily agglomerate to form particles in the micrometer size range.