Chemical Properties
Sodium silicate,NA2Si03 also known as a liquid glass, silicate of soda, sodium metasilicate, and soluble glass, is a grayish-white crystalline powder that has a melting point of 1088 °C (1990 °F). It is soluble in water and has strong detergent and emulsifying properties. Sodium silicate is used to fireproof textiles, insulate electric wire, protect wood and porous stone, grease proof paper containers, and as a catalyst in refining high-octane gasoline.
Definition
ChEBI: An inorganic sodium salt having silicate as the counterion.
Description
Sodium silicate, 2Na2OSiO2, is the simplest form of glass. It is found as lumps of greenish glass soluble in steam under pressure, white powders of varying degrees of solubility, or liquids cloudy or clear. It is noncombustible; however, when the powdered form is suspended in air, it could cause a dust explosion if an ignition source is present. Breathing the dust may also cause health problems. The glass form could also create a hazard to responders in an accident. It is not listed as a hazardous material in the DOT Hazardous Materials Tables. The primary uses are as catalysts, soaps, adhesives, water treatment, bleaching, waterproofing, and flame retardant.
Purification Methods
Sodium silicate solution [1344-09-8] pK 1 9.51, pK 2 11.77 (for silicic acid, H4S i O4) Purify by contact filtration with activated charcoal.
Flammability and Explosibility
Notclassified
Industrial uses
Sodium silicate (liquid silicate, metso or sodium silicate beads) has the general formula
Na2SiO3. The liquid silicates (“O” and “N” brand) are clear, thick liquids, while silicate
powder is a granular, white substance. Sodium silicate is a mixture of sodium or potassium
salts. Sodium silicates are primarily used in mineral flotation practice.
Industrial uses
Sodium silicate is widely used in mineral flotation as depressant, dispersant and as controlling
agent of some soluble ions For example, sodium silicate interacts with calcium
ions in solution forming nearly insoluble calcium silicate. For industrial and sulfatetype
minerals (barite), sodium silicate is usually part of the reagent scheme. Sodium silicate
is extensively used in base-metal flotation.
Toxicology
Aqueous solutions of Sodium Silicate species are a part of a chemical continuum of silicates based on an equilibrium of alkali, water, and silica. This compound, administered orally, is readily absorbed from the alimentary canal and excreted in the urine. Dogs fed 2.4 g/kg/day of Sodium Silicate for 4 weeks had gross renal lesions but no impairment of renal function. It was a severe eye irritant in some eye irritation studies but was irritating or nonirritating in others. A skin freshener containing Sodium Silicate was nonirritating. Rats given Sodium Silicate (600 and 1200 ppm of added silica) in the drinking water in reproductive studies produced a reduced number of offspring: 67% of controls at 600 ppm and 80% of controls at 1200 ppm[1].
References
[1] Elmore, Amy R. “Final report on the safety assessment of potassium silicate, sodium metasilicate, and sodium silicate.” International Journal of Toxicology 24 Suppl 1 (2005): 103–17.
