What Is Sodium Borate?
Sodium borate is a sodium-containing borate mineral.
Sodium borate is the generic name for a variety of compounds, including sodium di-, tetra-, penta-, hexa-, and octa-borates, the most common of which is sodium tetraborate, also known as borax.
Sodium tetraborate is produced by mixing calcium borate with sodium carbonate.
Uses of Sodium Borate
Sodium borate is available in both anhydrous and hydrated forms, but when used, the hydrated form is most often used. Sodium tetraborate decahydrate, the most common, is used industrially as a raw ore for boron.
For example, sodium borate is not only used to coat glass and ceramics, but can also be used in detergents, staining, wood and other preservatives, pesticides, and insecticides. It is also distributed for general use in its hydrated form as borax.
Sodium borate can also be used as a fertilizer for boron, an essential trace element in plants, and as a radiation shielding material for nuclear reactors.
Properties of Sodium Borate
Sodium borate is solid at room temperature. It is colorless to white and becomes opaque when exposed to air.
Sodium borate has a Mohs hardness of 2.5, a specific gravity of 1.7, and a solubility of 4.7 g/100 mL in 20°C water. The chemical composition of sodium tetraborate, the most common type of sodium borate, is Na2B4O5(OH)4・8H2O, which is the decahydrate of Na2B4O7.
It is monoclinic and tends to fuse in air, losing its crystalline water to form tincalconite, which has the structure Na2B4O5(OH)4・3H2O.
Other Information on Sodium Borate
1. Where Sodium Borate Is Produced
Sodium borate is often found at sites where salt lakes have dried up. In ancient times, it was brought to Europe from dried lakes in Tibet, where it was used as a raw material for special glass and enamel paints.
In addition, producing areas such as Death Valley in the western part of the Americas have been discovered one after another. Currently, in addition to the United States, Russia, Turkey, and Argentina, it is also produced in Italy, Germany, and other countries.
2. Reaction of Sodium Borate
The reaction in which boron cross-links polymers to form a gel can be used. In fact, sodium borate is often used to make slime in science experiments and free research.
Sodium borate can be mixed with glass to make borosilicate glass, which is resistant to thermal shock and chemical erosion. This glass can be used as a raw material for heat-resistant glass.
3. Applications of Sodium Borate
Sodium borate has a wide variety of applications. Specifically, it can be used for qualitative analysis and as a glaze dissolver for ceramics. Sodium Borate becomes anhydrous when heated to 350-400°C, and upon further heating, it melts at 878°C, turning into a clear, colorless glassy substance.
It can then be used as a melting agent to melt many metal oxides, which are known to exhibit a distinctive color depending on the metal. Aqueous solutions of sodium borate are slightly alkaline and can be used in detergents and antiseptics because of their cleaning and disinfecting properties.
Like boric acid, sodium borate is also used to clean and disinfect the eyes. In addition, sodium borate is added to silver halide photographic developing solutions as an alkaline adjuster.
4. Past Applications of Sodium Borate
Sodium borate was used when the nuclear ship Mutsu suffered a radiation leak due to a design error in the shielding ring. In other words, in order to identify the location of the radiation, a sheet of rice mixed with sodium borate was used as an improvised shielding material, and the radiation levels were measured at different locations on the reactor containment vessel.