Titanium Dioxide (TiO₂) is a naturally occurring compound that is one of the most widely used white pigments in the world. It is a white, odorless, and insoluble solid with a high refractive index and strong UV-blocking properties. Titanium dioxide is produced through several processes, including the sulfuric acid method and the chloride method, and is commonly found in products ranging from paints to cosmetics to food products.
The mineral form of titanium dioxide, known as anatase or rutile (depending on the crystal structure), gives it its characteristic white opacity. TiO₂ is also highly valued for its non-toxic, stable, and non-reactive properties, making it a safe choice for a variety of applications.
Properties of Titanium Dioxide:
- Molecular Formula: TiO₂
- Molar Mass: 79.87 g/mol
- CAS Number: 13463-67-7
- Chemical Structure: Titanium dioxide consists of a titanium (Ti) atom bonded to two oxygen (O) atoms, forming a crystal lattice.
- Reactivity:
- TiO₂ is non-reactive in most conditions. It is insoluble in water and most solvents and is chemically stable at a wide range of temperatures. However, at very high temperatures, it can react with halogens to form titanium halides.
- It is photoactive and can catalyze certain reactions when exposed to UV light.
- In the anatase form, TiO₂ is used as a photocatalyst for environmental purification and water treatment applications.
- Appearance: A white powder or solid (depending on the particle size and crystalline structure).
- Density: 4.23 g/cm³.
- Melting Point: 1,843°C (3,349°F).
- Boiling Point: TiO₂ does not have a defined boiling point since it decomposes before it boils.
- Solubility: Insoluble in water and most organic solvents.
- Refractive Index: High refractive index of 2.5, making it very effective in pigments and coatings.
- Opacity: Titanium dioxide is highly opaque, which is the reason it is widely used as a whitening agent.
- Particle Size: TiO₂ in its nanoparticle form is widely used in many applications for its light-scattering properties and its ability to enhance product performance.
Uses of Titanium Dioxide:
- Pigments: Widely used as a white pigment in paints, coatings, and plastics.
- Cosmetics: Used in sunscreen for UV protection and in other cosmetic products.
- Paper: Used as a brightener in paper products.
- Food Additive: Used as a food coloring agent (E171).
- Catalysis: Used in certain chemical reactions, particularly in photocatalysis.