Titanium dioxide (TiO2)

Titanium dioxide (TiO2), alternatively referred to as titania, titanium(IV) oxide, or just titanium, is a bright white inorganic chemical that has been used for almost a century. Because it is non-toxic, non-reactive, and luminous, it is mainly used as a vibrant colorant in many products. It is one of the whitest and brightest-known pigments because of these qualities, enabling it to improve the whiteness and brightness of many other materials. TiO2’s ability to reflect light and both scatter and absorb UV rays adds to its significance in the fight against climate change and skin cancer prevention.

Titanium and oxygen combine to form the chemical compound TiO2, which is found in nature. It is an odorless, white powder with unique qualities that make it highly beneficial in various businesses. Due to its chemical inertness, which prevents it from reacting with other substances, titanium dioxide is a stable material that may be used in multiple applications and industries. TiO2 is the chemical formula for titanium dioxide, which comprises one titanium atom and two oxygen atoms. This naturally occurring chemical is created when titanium and atmospheric oxygen interact. It is present in minerals that are part of the planet’s crust and frequently combines with other elements like iron and calcium.

Chemical composition: TiO2 comprises one titanium atom bonded to two oxygen atoms.
Appearance: It is a bright white substance, often referred to as “the perfect white” or “the whitest white” due to its powerful whitening qualities.
Crystal structure: TiO2 can exist in three primary crystalline forms – rutile, anatase, and brookite – each with slightly different properties.
Primary use: It is widely used as a pigment in various products, providing whiteness, opacity, and brightness.
Other applications: Beyond its use as a pigment, TiO2 has photocatalytic properties and UV-absorbing capabilities and can be used in nanoparticle form for specialized applications.

TiO2 boasts the formula TiO2, indicating one titanium atom bonded to two oxygen atoms. It’s incredibly stable and doesn’t readily react with other chemicals. TiO2 has a high refractive index, indicating it bends light effectively, contributing to its bright white color.

Interestingly, TiO2 exists in three primary crystal forms: anatase, rutile, and brookite. Anatase and rutile are the most common and commercially relevant forms, each with slightly different properties influencing their specific applications.

Titanium dioxide has a unique structure, with titanium atoms bonded to six oxide anions in an octahedral geometry. The oxides are arranged in a tetragonal crystal structure, widespread for other metal dioxides and difluorides. Molten titanium dioxide has a local structure where each Ti is coordinated to about five oxygen atoms, distinct from the crystalline forms where Ti coordinates to 6 oxygen atoms.

• Density: The density varies depending on the crystalline form, with rutile having a 4.23 g/cm³ density and anatase at 3.78 g/cm³.
• Refractive Index: This property is crucial for its use as a pigment. Rutile has a refractive index of 2.609, anatase at 2.488, and brookite at 2.583.
• Bond Type: The bonds in TiO2 exhibit ionic and covalent characteristics, contributing to its chemical reactivity and stability.
• Photocatalytic Activity: Nanosized anatase TiO2, in particular, demonstrates photocatalytic activity under UV irradiation, capable of breaking down pollutants and producing hydroxyl radicals.
• Hardness and Bulk Modulus: Although initial claims suggested cotunnite-type TiO2 was one of the hardest known oxides, subsequent studies indicated lower values, highlighting the complexity of accurately assessing these properties.

Nanosized titanium dioxide, particularly in the anatase form, exhibits photocatalytic activity under ultraviolet (UV) irradiation. This property is attributed to the ability of TiO2 to break down water into hydrogen and oxygen, making it a potential material for energy production. The photocatalytic activity can be enhanced by doping the oxide with nitrogen ions or metal oxides like tungsten trioxide.

In cosmetics, it’s used in sunscreens, foundations, and powders for UV protection and a smooth finish. Industrially, it is a pigment in paints, coatings, plastics, paper, ink, and textiles due to its excellent opacity and brightness. The food industry uses it as a food additive (E171) to whiten and brighten products like candies, dairy products, and baked goods.

Titanium dioxide is produced through two main processes: the sulfate process and the chloride process. The sulfate process involves reacting titanium-rich ore with sulfuric acid, while the chloride process involves converting titanium to titanium tetrachloride and then oxidizing it at high temperatures.

Titanium dioxide is a versatile and widely used compound with a range of applications. Its unique properties, such as photocatalytic activity and ability to scatter and reflect light efficiently, make it an essential component in various industries.