Barium sulphate has the chemical formula BaSO4 and it is a barium salt of sulphuric acid. It is an odorless white crystalline powder in physical appearance. Barium sulphate is insoluble in water, dilute acids and alcohol and concentrated sulphuric acid. It can be discovered as the main commercial source of barium and materials prepared from it.
The highly impure mineral barite is processed by heating with coke or carbon via thermal reduction to give barium sulphide. Barium sulphide is treated with sulphuric acid or sulphate salts to obtain barium sulphate of high purity. The barium sulphate produced with this method is known as “blanc fixe” which is “permanent white” in French. In the laboratory, barium sulphate is produced from combining solutions containing barium ions and sulphate salts.
Barium sulphate is used as a white pigment for paper pigment due to its white appearance. In ink-jet printing, barium sulfate is employed to improve the brightness and whiteness of the paper. For photographic paper, a thin layered coating of barium sulfate would help to increase the reflectiveness of the image.
Paint and Coating
Barium sulphate is used as a pigment for paint and coating. The precipitated BaSO4 is mixed with co-precipitated zinc sulfide yielding a white protective coating pigment known as lithophone. It is also used to make fine pigment particles known as blanc fixe (French for “permanent white”) when combined with sodium sulfide. Due to its high specific gravity, it can be considered as a filler when other compounds are not suitable.
Barium sulphate is used an integral component in oil well drilling fluid and it increases the density of fluid. Suspension of barium sulfate is digested orally for X-ray imaging and other clinical diagnostic procedures. As a coating agent, it is useful in the casting of copper anode plates as well. In addition, barium sulfate serves a white pigment in paints, modifying consistency in paints.