titaniumdioxide

Titanium dioxide (TiO2), commonly called titania, is an inorganic compound used primarily as a white pigment. It occurs naturally as the minerals rutile and anatase, but the commercial product is synthetic and highly pure.

Two crystalline forms dominate: anatase and rutile; rutile is the more thermodynamically stable phase at high temperatures, while anatase is often preferred for pigment properties or photocatalysis. Pigment-grade TiO2 consists of submicron to few-micrometer particles; nanoscale forms are used for specialized applications.

TiO2 has a high refractive index (~2.5), strong covering power, chemical inertness, UV filtering ability, and is insoluble in water. These properties give it its brightness, opacity, and durability in coatings.

Production methods include the sulfate process and the chloride process, both derived from titanium-containing ores such as ilmenite and rutile. Purification and surface treatments enhance dispersibility and compatibility with paints, plastics, and papers.

Major applications include pigments for paints, coatings, plastics, and paper; UV-blocking components in sunscreens and cosmetics; photocatalysis for air and water purification and self-cleaning surfaces; and use in ceramics and some electronic devices.

Safety and regulation: TiO2 is of low acute toxicity and is insoluble. Inhalation of fine TiO2 dust is a reported health concern and is the primary occupational risk; IARC classifies inhaled TiO2 as possibly carcinogenic to humans (Group 2B). Ingestion is considered a low hazard. Environmental persistence is common due to its inert nature.