Titanium dioxide is a simple inorganic compound produced as a pure
white powder. It is commonly available in two main crystal forms,
anatase and rutile and typically supplied to the market in a range
of package sizes or in bulk. Sales as water based slurry are also
common in the China. It is the properties and uses of titanium
dioxide that make it an interesting and valuable chemical and
overshadow its rather mundane appearance.
It has a very high refractive index of ca. 2.7 which compares with
values of only 2.0 and 1.6 for zinc oxide and china clay
respectively. This high refractive index gives the potential for
producing much greater opacity or hiding power, making TiO2 a much
better pigment than the other chemicals mentioned.
So titanium dioxide is the best white pigment available but this
does not just restrict its use to anything that is white, the
opacity is also used in combination with coloured pigments to give
them the required hiding power they need. The crystal size of the
TiO2 also needs to be optimised to maximise its effectiveness as a
pigment, the optimum for light scattering being around 0.2 µm.
These properties give a highly versatile product with worldwide
sales of around 4.5 million t. The main uses are in coatings such
as paints, followed by plastics, then high grade papers and
printing inks. There is also a wide range of minor uses in total
volume terms many of which are still important and include uses
such as pharmaceuticals, foodstuffs, and cosmetics.
Applications of titanium dioxide other than pigment production are
as follows:
Production of fiber optic products
Titanium dioxide, with a chemical purity of 99.9998%, is used in
producing optical fiber products, medical equipment, and the
radio-electronic industry. In manufacturing ultra-pure glasses,
titanium dioxide serves as a purity reference.
Synthetic fibers and textiles
For matting twisted fibre.
Cosmetics
For protection against ultraviolet radiation in sunblock creams,
for higher whitening effect of toothpastes, soaps, etc.
Food industry
For higher whitening effect in products, for protection of product
package color (plastics) against ultraviolet radiation.
Pharmaceutical industry
For higher whitening effect in pharma products.
Printing paint
To increase weather resistance of coatings.
Catalyst
Photocatalyst and inert ceramic base material for active
components.
Nanotechnology
Titanium dioxide nanopowders are used for air purification in
cities, in producing nanofiber paper based on TiO2, in hydrogen
energy, etc.
