Titanium dioxide is a white inorganic compound, which has been used for around 100 years in a vast number of diverse products. It is depended on it for its non-toxic, non-reactive and luminous properties, which safely heighten the whiteness and brightness of many materials.

It is the whitest and brightest of known pigments, with reflective qualities; it can also both scatter and absorb UV rays.

What are the physical properties of titanium dioxide?

Titanium dioxide has a number of unique characteristics that make it ideally suited to many different applications.

It has an extremely high melting point of 1,843ºC and boiling point of 2,972ºC, so occurs naturally as a solid, and, even in its particle form, it is insoluble in water. TiO2 is also an insulator.[12][13]

Unlike other white materials that may appear slightly yellow in light, because of the way TiO2absorbs UV light, it doesn’t have this appearance and appears as pure white.

Importantly, titanium dioxide also has a very high refractive index (its ability to scatter light), even higher than diamond. This makes it an incredibly bright substance and an ideal material for aesthetic design use.

Another crucial property of titanium dioxide is that it can show photocatalytic activity under UV light. This makes it effective for environmental purification, for different kinds of protective coatings, sterilisation and anti-fogging surfaces, and even in cancer therapy.[14][15][16]

§ Brilliant
Brilliance, colour strength, opacity and pearlescence unlike any other substances.

§ Resistant
Stability to heat, light and weathering prevents degradation of paint, in films and embrittlement of plastics.

§ Protective
Ability to scatter and absorb UV radiation makes TiO2 a crucial ingredient for sunscreen, protecting the skin from harmful, cancer-causing UV rays.

§ Non-toxic
Being non-toxic and non-reactive it can be used in food and pharmaceuticals without affecting other ingredients.

§ Powerful
Is used as a photocatalyst in solar panels as well as reducing pollutants in the air.

What are the forms of titanium dioxide?

TiO2 possesses different qualities depending on whether it is produced as pigment-grade or nanomaterial-grade. Both forms are tasteless, odourless and insoluble.

Pigment-grade TiO2 particles are approximately 200-350nm in dimension and this form accounts for 98 percent of total production. It is used mainly for light scattering and surface opacity applications, such as paint – this includes its use as a base for various colour paints or as a standalone ‘brilliant’ white.

Nano, or ultrafine TiO2 comprises of primary particles sized less than 100nm. In this grade, titanium dioxide is transparent (colourless) and boasts improved UV scattering and absorbing properties compared with larger particle-size, pigment-grade TiO2.

What is titanium dioxide made of?

Titanium is one of the most common metals on earth, but it does not occur naturally in this elemental form. Titanium dioxide – also known as titanium (IV) oxide or titania – is the naturally occurring compound created when titanium reacts with the oxygen in the air. As an oxide, titanium is found in minerals in the earth’s crust. It also found with other elements, including calcium and iron.[17]

Its chemical formula is TiO2, which means it consists of one titanium atom and two oxygen atoms (hence dioxide). It has a CAS (Chemical Abstracts Service) registration number of 13463-67-7.[18]

TiO2 is typically thought of as being chemically inert, meaning it doesn’t react with other chemicals and is, therefore, a stable substance that can be used in many different industries and for a variety of applications.[19]

Where does titanium dioxide come from?

Titanium dioxide itself was officially first named and created in a laboratory in the late 1800s. It wasn’t mass manufactured until the early 20th century, when it started to take over as a safer alternative to other white pigments.[17]

The element titanium and the compound TiO2 are found around the world, linked to other elements such as iron, in several kinds of rock and mineral sands (including a component of some beach sands). Titanium most commonly occurs as the mineral ilmenite (a titanium-iron oxide mineral) and sometimes as the mineral rutile, a form of TiO2. These inert molecular compounds must be separated through a chemical process to create pure titanium dioxide.

How is titanium dioxide extracted?

How pure titanium dioxide is extracted from titanium-containing molecules depends on the composition of the original mineral ores or feedstock. Two methods are used to manufacture pure TiO2: a sulphate process and a chloride process.

The principal natural source of titanium dioxide is mined ilmenite ore, which contains 45-60 percent TiO2. From this, or an enriched derivative (known as titanium slag), pure TiO2 can be produced using the sulphate or chloride process.

Sulphate and chloride methods

Of the two methods of extraction, the sulphate process is currently the most popular method of producing TiO2 in the European Union, accounting for 70 percent of European sources. The remaining 30 percent is the result of the chloride process. On a global level, it is estimated about 40-45 percent of the world’s production is based on the chloride process.

As a widely used substance with multiple applications, research is being carried out to improve the production process to reduce the levels of chemicals used and waste produced, and to recycle any by-products.

The future of titanium dioxide

For a substance that is relatively unknown to the public, it’s amazing how many everyday products titanium dioxide can be found in. Because of its many varied properties, our skin, cities, cars, homes, food and environment are made brighter, safer, more resilient and cleaner by titanium dioxide. With a legacy of 100 years of safe commercial use, titanium dioxide is only going to become more vital as our environment faces greater challenges from a growing population