Borax pentahydrate, also known as sodium borate pentahydrate, has a molecular formula of Na2B4O7·5H2O, CAS number: 12179-04-3, and is one of the important boron compounds. Borax pentahydrate is a white crystalline powder with a density of 1.815g/cm3. Melting point 75℃. It is easily soluble in hot water and glycerol, slightly soluble in ethanol and carbon tetrachloride. The aqueous solution is alkaline. It completely loses crystal water when heated to 120℃. It is stable in dry air, but slowly absorbs moisture in the air under humid conditions and becomes borax decahydrate. It has bactericidal, disinfecting, fluxing and high-temperature adhesion properties.
Production method:
It is made from sodium tetraborate decahydrate solution, controlling the feeding temperature above 70℃, recrystallization at a crystallization temperature above 60℃, filtering, and drying below 120℃.
It can also be made from natural boron ore by dissolving it in hot water, filtering and separating it, cooling and crystallizing it, controlling the crystallization temperature above 60℃, and washing it with a mother liquor with a concentration of 25%.
Application of Borax Pentahydrate:
Glass industry: Borax Pentahydrate is used as a raw material in the glass industry to improve the UV transmittance, transparency and heat resistance of glass, and then manufacture optical glass and heat-resistant and corrosion-resistant glass.
Enamel industry: In the enamel industry, Borax Pentahydrate is used as a glaze, which is applied to the metal surface to enhance the durability of the enamel, while making the enamel not easy to fall off and shiny.
Agriculture: Borax Pentahydrate is used as a herbicide and soil fungicide.
Daily chemical field: It is also used as a softener for water in cosmetics, and to manufacture preservatives and rust inhibitors.