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Sodium Silicoflouride is also known as sodium fluorosilicate, sodium fluosilicate and sodium hexafluorosilicate.
Sodium Silicoflouride has a number of applications and can be used as a coagulant agent for latex, in the manufacture of non ferrous metal treatment compounds, in aluminum flux production, as a Pacifying agent for vitreous enamels and opalescent glass and for fluoridation of potable water.
Sodium Silicoflouride is a white crystalline solid.
CAS: 16893-85-9
MF: F6Na2Si
MW: 188.06
EINECS: 240-934-8
Synonyms
ens-zemweevilbait;ent1,501;fluosilicatedesodium;Natriumhexafluorsilikat;Sodium fluorosilicat;SodiuM fluosilicide;Silicate(2-), hexafluoro-, sodium (1:2);SODIUM SILICOFLUORIDE, REAGENTSODIUM SILICOFLUORIDE, REAGENTSODIUM SILICOFLUORIDE, REAGENTSODIUM SILICOFLUORIDE, REAGENT
Sodium Silicoflouride appears as white crystal, crystalline powder or colorless hexagonal crystals.
Sodium Silicoflouride is odorless and tasteless.
Sodium Silicoflouride's relative density is 2.68; it has moisture absorption capability.
Sodium Silicoflouride can be dissolved in a solvent such as ethyl ether but insoluble in alcohol.
The solubility in acid is greater than that in water.
Sodium Silicoflouride can be decomposed in alkaline solution, generating sodium fluoride and silica.
After searing (300 ℃), Sodium Silicoflouride is decomposed into sodium fluoride and silicon tetrafluoride.
In 25 degrees, the Sodium Silicoflouride has its water solubility being 0.78%.
Upon production, addition of an excess amount of sodium sulfate or sodium chloride can increase the concentration of sodium ions in the system, thereby increasing the solubility product of fluorine silicate and sodium ions, so that sodium fluoride can be subject to more complete precipitation.
Sodium Silicoflouride is the byproduct in the production of calcium phosphate or the production of fluoride salt in aluminum factory.
Sodium Silicoflouride generally appears as a white crystalline powder with low solubility in water (being 1% or less at room temperature), and the water solubility increases slightly with increasing temperature.
The aqueous solution of Sodium Silicoflouride is acidic (pH3).
Sodium Silicoflouride is due to that its hydrolysis product contains hydrofluoric acid.
Reduction of the acidicity of the solution facilitates the hydrolysis of sodium fluorosilicate.
When pH is lower than 3.5-3.55, the hydrolysis reaction is stabilized.
When the pH is equal to 4, the hydrolysis reaction rate is significant.
When the pH value is equal to 8-8.5, the sodium fluorosilicate can be completely hydrolyzed to exhibit as silica gel and precipitated out.
Therefore, when sodium fluorosilicate is added to the water glass, in addition to hardening effect of precipitation of silicon dioxide gel caused by the neutralization of the sodium hydroxide in the solution of water glass, the sodium fluorosilicate itself is also a source of silica gel.
Sodium Silicoflouride can be used as the insecticide in agriculture, the milky agent of enamel, the corrosion production agent of opal glass, wood preservatives and the raw material for the production of other kinds of fluoride as well as being applied to the smelting of beryllium and aluminum and pharmaceuticals, leather and rubber industry.
In the refractory material, Sodium Silicoflouride can be used as the coagulant as the water glass binding agent.
Since Sodium Silicoflouride has a low water solubility, it reaction with the water glass is slow and gradual.
Sodium Silicoflouride can not only boost the construction but also has a high density and strength of the cured products.
Sodium Silicoflouride is most commonly used in the inorganic material binding with the water glass.
Sodium Silicoflouride is a compound with the chemical formula Na2[SiF6].
Unlike other sodium salts, Sodium Silicoflouride has a low solubility in water.
Sodium Silicoflouride Chemical Properties
Melting point: melts at red heat, decomposing [MER06]
Boiling point: 620℃[at 101 325 Pa]
Density: 2.68 g/mL at 25 °C(lit.)
Vapor pressure: 0.01Pa
Refractive index: 1.310
Solubility: insoluble in ethanol
Form: Crystals
Color: White
Specific Gravity: 2.68
Odor: odorless
Water Solubility: Slightly soluble in water. Solubility increases with temperature. Insoluble in alcoholSlightly soluble in water. Insoluble in alcohol.
Merck: 14,8624
Exposure limits ACGIH: TWA 2.5 mg/m3
NIOSH: IDLH 250 mg/m3; TWA 2.5 mg/m3
Stability: Stable. Incompatible with oxidizing agents, water. Moisture sensitive.
LogP: 0.001
CAS DataBase Reference: 16893-85-9(CAS DataBase Reference)
EPA Substance Registry System: Sodium Silicoflouride (16893-85-9)
Sodium Silicoflouride appears as colorless hexagonal crystals.
Sodium Silicoflouride is odorless and tasteless.
Sodium Silicoflouride has hygroscopicity.
Sodium Silicoflouride can be dissolved in a solvent such as ethyl ether but insoluble in alcohol with its solubility in acid is being greater than in the water.
Uses
In enamels for china and porcelain; manufacture of opal glass; as insecticide, rodenticide; mothproofing of woolens.
Fluoridating agent for drinking water.
Intermediate in production of synthetic cryolite.
Sodium Silicoflouride is used as a additive for water fluoridation, opal glass raw material and in ore refining.
Sodium Silicoflouride is also used in the preparation of other fluoride chemicals like sodium fluoride, sodium hexafluoroaluminate, potassium hexafluorosilicate, ammonium fluoride and calcium fluoride.
Sodium Silicoflouride finds application as flotator, component for wet etching, wood preservative, brazing flux and welding compound.
Sodium Silicoflouride is an active component of concrete.
Sodium Silicoflouride is used in some countries as additives for water fluoridation, opal glass raw material, ore refining, or other fluoride chemical (like sodium fluoride, magnesium silicofluoride, cryolite, aluminum fluoride) production.
Sodium Silicoflouride is used for extraction of beryllium from beryl, by roasting the mineral with it at 700-750 °C, leaching the soluble fluoride with water, and then precipitating it as Be(OH)2 at about pH 13.
Sodium Silicoflouride also is an ingredient in some ceramic cements.
Industrial uses
Sodium Silicoflouride is a white, isomorphous powder.
Solubility in water is similar to that of NaF.
In acid pH, solubility improves.
Commercially, Na2SiF6 is produced by treatment of fluorosilic acid with sodium chloride, as shown in the following reaction: H2SiF6 + 2NaCl = Na2SiF6 + 2HCl
Health Hazard
Inhalation of dust may irritate nose and throat.
Ingestion causes symptoms similar to fluoride poisoning; compound is highly toxic; initial symptoms include nausea, cramps, vomiting, diarrhea, and dehydration; in severe cases, convulsions, shock, and cyanosis are followed by death in 2-4 hr.
Contact with eyes causes irritation.
Contact with skin causes rash, redness, and burning, sometimes followed by ulcer formation.
Production method
Calcium superphosphate byproduct method: use sulfuric acid and ground phosphate rock for production of superphosphate or fluorine-containing waste gas during extraction of phosphate with water absorbing silicon tetrafluoride to make it into fluorosilicate.
When the concentration of fluorine acid solution reaches 8% to 10%, stand static for clarification and remove the impurities with the clarified fluorine silicate solution being added of sodium chloride (being excess of about 25%) for reaction of sodium fluorosilicate.
Further go through centrifugation isolation, washing, air drying at a temperature below 300 ℃ and then pulverize to obtain the finished product of Sodium Silicoflouride.
H2SiF6 + 2NaCl → Na2SiF6 + 2HCl
