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Sodium silicofluoride is an inorganic compound that appears as a white, odorless crystalline powder, moderately soluble in water, and hydrolyzing in acidic conditions to release hydrofluoric acid and silicic acid derivatives.
Industrially, Sodium silicofluoride is widely used as a fluoridating agent in water treatment, a flux in metallurgy, and an additive in glass, ceramics, and enamels, while also serving as an intermediate in the production of fluorine-containing chemicals.
Despite its versatility, sodium silicofluoride is toxic due to its fluoride content, requiring strict handling measures and regulatory oversight to balance its industrial utility with public health and environmental safety.
CAS Number: 16893-85-9
EC Number: 240-934-8
Molecular Formula: Na2SiF6
Molecular Weight: 188.06 g/mol
Synonyms: Sodium hexafluorosilicate, 16893-85-9, Sodium fluorosilicate, Sodium fluosilicate, SODIUM SILICOFLUORIDE, disodium;hexafluorosilicon(2-), Disodium hexafluorosilicate, MFCD00003491, Sodium hexafluorosilicate [ISO], DTXSID9036933, 806AV2E065, Salufer, Safsan, Silicate(2-), hexafluoro-, sodium (1:2), Super prodan, Destruxol applex, Ortho earwig bait, Ortho weevil bait, Ens-zem weevil bait, Fluosilicate de sodium, Sodium silica fluoride, Caswell No. 771, Disodium silicofluoride, Sodium hexafluosilicate, Na2SiF6, Natriumhexafluorosilicat, Silicon sodium fluoride, Sodium silicon fluoride, PSC Co-Op weevil bait, Natriumsilicofluorid [German], HSDB 770, Disodium hexafluorosilicate (2-), Natriumsilicofluorid, EINECS 240-934-8, ENT 1,501, UN2674, Silicate(2-), hexafluoro-, disodium, EPA Pesticide Chemical Code 075306, Fluorosilicate de sodium [ISO-French], F6Na2Si, Fluorosilicate de sodium, AI3-01501, NATRUM SILICOFLUORICUM, Sodium hexafluorosilicate, 98%, DTXCID7016933, UNII-806AV2E065, Tox21_302311, NATRUM SILICOFLUORICUM [HPUS], SODIUM HEXAFLUOROSILICATE [MI], SODIUM SILICOFLUORIDE [MART.], SODIUM HEXAFLUOROSILICATE [HSDB], NCGC00255590-01, SODIUM SILICON FLUORIDE (NA2SIF6), CAS-16893-85-9, DISODIUM HEXAFLUOROSILICATE (NA2SIF6), NS00084852, Sodium fluorosilicate [UN2674] [Poison], C19040, EC 240-934-8, Q532908
Sodium silicofluoride is an inorganic compound that appears as a white, odorless crystalline powder.
Sodium silicofluoride is moderately soluble in water and insoluble in alcohol, releasing hydrofluoric acid and silica when hydrolyzed in acidic conditions.
Industrially, sodium silicofluoride is used as a fluoridating agent in water treatment, as an intermediate in the manufacture of aluminum and other fluorine-containing compounds, and as an additive in ceramics, glass, and enamels to improve durability and resistance.
Sodium silicofluoride is also employed as a flux in metallurgy and as an insecticide in some formulations.
Due to its fluoride content, sodium silicofluoride is toxic if ingested in significant quantities, and prolonged exposure may cause irritation of the skin, eyes, and respiratory system; therefore, it must be handled with appropriate protective measures.
Sodium silicofluoride is a compound with the chemical formula Na2[SiF6].
Unlike other sodium salts, Sodium silicofluoride has a low solubility in water.
Sodium silicofluoride is an inorganic chemical compound belonging to the family of fluorosilicates.
Sodium silicofluoride occurs as a fine, white, crystalline powder that is odorless, relatively stable under normal conditions, and only moderately soluble in water, while remaining insoluble in alcohol and most organic solvents.
When dissolved, Sodium silicofluoride undergoes slow hydrolysis, especially in acidic media, releasing hydrofluoric acid (HF) and silicic acid derivatives, which accounts for many of its industrial and toxicological properties.
Because of its fluoride content, sodium silicofluoride has long been recognized as a substance of both practical value and health concern, requiring careful handling and regulated use.
From an industrial perspective, sodium silicofluoride has multiple important applications.
Sodium silicofluoride is used as a fluoridating agent in municipal water treatment programs, though its use in this area has sometimes been debated due to health and environmental concerns.
In the metallurgical industry, Sodium silicofluoride serves as a fluxing agent in aluminum refining and other metal processing operations, where it helps lower melting points and improve the efficiency of smelting processes.
Sodium silicofluoride also finds use in the production of specialized ceramics, enamels, and glasses, imparting improved durability, gloss, and resistance to chemical attack.
In chemical manufacturing, sodium silicofluoride acts as an intermediate in the synthesis of various fluorine compounds and is used in the production of insecticides, rodenticides, and wood preservatives, owing to its pesticidal properties.
Additionally, Sodium silicofluoride can function as an additive in abrasive cleaning agents and certain types of cement formulations.
From a safety standpoint, sodium silicofluoride must be regarded as a hazardous substance.
Inhalation of Sodium silicofluoride's dust can irritate the respiratory tract, while contact with skin and eyes may cause significant irritation or burns due to its fluoride ions.
Ingestion of large amounts is toxic and may lead to systemic fluoride poisoning, manifesting as nausea, abdominal pain, muscle weakness, and—in severe cases—damage to bones and teeth due to fluoride accumulation.
Long-term occupational exposure without protective equipment may result in chronic health effects, including skeletal fluorosis.
Because of these risks, international safety standards and material safety data sheets (MSDS) recommend strict precautions when handling sodium silicofluoride, such as the use of gloves, goggles, respiratory protection, and effective ventilation systems.
Environmentally, sodium silicofluoride is considered hazardous if released in significant amounts, as it can contaminate soil and water, affecting aquatic organisms and altering ecosystems.
Sodium silicofluoride's persistence in the environment is partly mitigated by its tendency to hydrolyze into less stable products, but proper disposal and waste management are essential to minimize risks.
For these reasons, many countries regulate Sodium silicofluoride's storage, transportation, and use, especially in food-related or agricultural contexts.
In summary, sodium silicofluoride is a versatile industrial compound with wide-ranging applications in metallurgy, ceramics, glassmaking, chemical synthesis, pest control, and water fluoridation.
However, Sodium silicofluoride's utility is counterbalanced by its toxicity and potential health hazards, which necessitate careful handling and strict regulatory oversight.
As such, Sodium silicofluoride remains a compound of industrial importance, scientific interest, and ongoing public health debate.
Market Overview of Sodium Silicofluoride:
The global sodium silicofluoride market is experiencing steady growth, driven by its diverse applications in water fluoridation, glass and ceramics manufacturing, metallurgy, and as an intermediate in chemical and pesticide production.
Valuations of the market vary depending on scope, with estimates ranging from about USD 125–150 million in 2024 to nearly USD 950 million by 2032, reflecting an expected compound annual growth rate (CAGR) of 3.5%–6%.
Asia-Pacific dominates demand, accounting for up to 40–70% of global consumption, largely due to industrial expansion in China and India, while North America and Europe follow, supported by established water treatment and manufacturing industries.
Demand is particularly strong for high-purity grades (≥ 99%), which are increasingly required in electronics and pharmaceutical applications.
Key growth drivers include rising urbanization, the push for improved water quality, and the use of fluorosilicates in advanced materials, though the market faces challenges from regulatory scrutiny over fluoride toxicity, competition from alternative chemicals, and raw material price volatility.
Overall, sodium silicofluoride maintains a stable market presence, with its balance of industrial utility and regulatory pressures shaping its future trajectory.
Uses of Sodium Silicofluoride:
Sodium silicofluoride is widely employed across multiple industrial sectors due to its chemical reactivity and fluoride content.
One of its most common uses is as a fluoridating agent in municipal water treatment, where Sodium silicofluoride helps prevent dental caries by increasing the fluoride concentration in drinking water.
In the glass, ceramic, and enamel industries, Sodium silicofluoride serves as a flux and opacifier, improving durability, gloss, and chemical resistance of final products.
In metallurgy, sodium silicofluoride is used in aluminum refining and other smelting processes to lower melting points and enhance metal recovery efficiency.
Sodium silicofluoride also acts as an intermediate in chemical synthesis, particularly in the production of other fluorine compounds, silicofluorides, and specialty chemicals.
Additionally, Sodium silicofluoride has been used in insecticides, rodenticides, and wood preservatives due to its pesticidal properties.
In the construction industry, Sodium silicofluoride may be added to certain cement and abrasive formulations to modify strength and hardness.
Beyond these, high-purity forms of sodium silicofluoride are increasingly important in electronics, pharmaceuticals, and specialty manufacturing, where controlled fluoride release is required.
Sodium silicofluoride has a wide spectrum of applications that span across public health, industry, agriculture, and specialty manufacturing, making it a compound of notable versatility.
One of its most significant uses lies in municipal water treatment, where Sodium silicofluoride has traditionally been applied as a fluoridating agent to increase fluoride levels in drinking water, thereby helping reduce the incidence of dental caries within populations.
Although Sodium silicofluoride's role in water fluoridation has been debated in some regions due to toxicological concerns, Sodium silicofluoride remains an economical and effective option in areas where controlled fluoride dosing is permitted.
In the glass, ceramics, and enamel industries, sodium silicofluoride serves as a fluxing agent, helping lower melting points, and as an opacifier, providing improved gloss, surface smoothness, and resistance to chemical attack.
Sodium silicofluoride is frequently incorporated into the production of specialized enamels, glazes, and vitreous coatings, where it enhances both functional durability and decorative qualities.
In the field of metallurgy, sodium silicofluoride plays an important role in the refining of aluminum and other non-ferrous metals.
Sodium silicofluoride facilitates smelting by lowering fusion temperatures, thus improving process efficiency and reducing energy costs.
In addition, Sodium silicofluoride is used as a flux to assist in separating metal impurities and in producing cleaner, more uniform alloys.
Within the chemical industry, sodium silicofluoride is an important intermediate, utilized in the manufacture of various fluorine-based chemicals, silicofluorides, and fluorosilicate salts.
Sodium silicofluoride's reactivity makes it a precursor for synthesizing specialty materials that are later used in industries ranging from pharmaceuticals to advanced coatings.
Another area of application is pesticides and wood preservation, where sodium silicofluoride has historically been formulated into insecticides, rodenticides, and preservatives due to its fluoride content and biocidal properties.
While usage in this sector has declined in some countries owing to stricter environmental regulations, Sodium silicofluoride remains relevant in certain agricultural and industrial settings.
In construction and abrasives, Sodium silicofluoride is added to specific types of cement, concrete, and polishing agents to enhance mechanical strength, wear resistance, and surface hardness.
This makes Sodium silicofluoride valuable in infrastructure materials and heavy-duty cleaning or grinding products.
More recently, high-purity grades of sodium silicofluoride have gained importance in advanced sectors such as electronics and pharmaceuticals.
In electronics, Sodium silicofluoride can be employed in processes where controlled fluoride release is needed, particularly in surface treatments and etching applications.
In pharmaceuticals and specialty manufacturing, Sodium silicofluoride's role as a fluorine source makes it useful in controlled chemical pathways where fluoride incorporation enhances stability, bioactivity, or performance.
Overall, sodium silicofluoride’s uses demonstrate a balance between traditional, large-scale industrial applications and more modern, high-tech demands.
From protecting public dental health and refining metals to enhancing ceramics and serving as a building block for advanced chemical synthesis, Sodium silicofluoride remains a multifaceted compound.
However, Sodium silicofluoride's toxicity and environmental persistence mean that each of these applications must be managed within strict safety and regulatory frameworks, ensuring that its benefits can be utilized without undue risk to human health or ecosystems.
Applications of Sodium Silicofluoride:
Sodium silicofluoride, used in the glass and enamel industry, also serves as a coagulant in latex.
Sodium silicofluoride can also be used in the production of zircon-based pigments, frits, and ceramic enamels.
Sodium silicofluoride also has limited use in the textile and pharmaceutical industries.
Sodium silicofluoride appears as white crystals, crystalline powder, or colorless hexagonal crystals.
Sodium silicofluoride is odorless and tasteless.
Sodium silicofluoride's relative density is 2.68 and it absorbs moisture.
Sodium silicofluoride is soluble in solvents such as ethyl ether, but insoluble in alcohol.
Sodium silicofluoride's solubility in acids is greater than in water.
Sodium silicofluoride can decompose in alkaline solutions, from which sodium fluoride and silica are produced.
After firing (300°C), Sodium silicofluoride decomposes into sodium fluoride and silicon tetrafluoride.
At 25°C, the solubility of Sodium silicofluoride in water is 0.78%.
Adding excess sodium sulfate or sodium chloride during production can increase the concentration of sodium ions in the system, thereby increasing the solubility product of fluorine silicate and sodium ions, allowing sodium fluoride to undergo further precipitation.
Sodium silicofluoride is a byproduct of calcium phosphate production in aluminum plants or fluoride salt production.
Sodium silicofluoride typically appears as a white crystalline powder with low solubility in water (1% or less at room temperature), and its solubility in water increases slightly with increasing temperature.
Fluorosilicate aqueous solutions are acidic (pH 3).
This is because the hydrolysis product contains hydrofluoric acid.
Decreasing the acidity of the solution facilitates the hydrolysis of Sodium silicofluoride.
When the pH is lower than 3.5–3.55, the hydrolysis reaction is balanced.
When the pH is equal to 4, the rate of the hydrolysis reaction is significant.
When the pH is equal to 8–8.5, Sodium silicofluoride can be completely hydrolyzed and precipitated, appearing as silica gel.
Therefore, when Sodium silicofluoride is added to water glass, in addition to the hardening effect of the precipitation of silicon dioxide gel formed by the neutralization of sodium hydroxide in the water bath solution, Sodium silicofluoride itself is also a source of silica gel.
The hydrolysis reaction rate is important.
When the pH value is equal to 8-8.5, Sodium silicofluoride can be completely hydrolyzed to form silica gel and precipitates.
Sodium silicofluoride can be used as an insecticide in agriculture, a milk absorbent for enamel, a corrosion inhibitor for opal glass, a raw material for the production of wood preservatives and other fluorides; Sodium silicofluoride can also be used for the smelting of beryllium and aluminum, as well as in the pharmaceutical, leather, and rubber industries.
Sodium silicofluoride can also be used as a coagulant in refractory materials and as a water glass binding agent.
Because Sodium silicofluoride has a low water solubility, its reaction with water glass is slow and sluggish.
This not only improves structure but also contributes to the high density and strength of hardened products.
Sodium silicofluoride is often used to bond inorganic materials with water glass.
Possible Application:
Sodium silicofluoride 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 silicofluoride 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 silicofluoride also is an ingredient in some ceramic cements.
Benefits of Sodium Silicofluoride:
Sodium silicofluoride offers a range of benefits that explain its long-standing role in industrial and municipal applications.
One of Sodium silicofluoride's most widely recognized advantages is in public health, where its controlled use in municipal water fluoridation programs contributes to the prevention of dental caries, especially in children and communities with limited access to dental care.
This preventive approach not only reduces healthcare costs but also improves overall quality of life by lowering rates of tooth decay.
Beyond water treatment, sodium silicofluoride provides substantial economic benefits in industry due to its ability to act as a cost-effective flux and additive.
In glass, ceramics, and enamel production, Sodium silicofluoride lowers melting points and enhances the chemical resistance, gloss, and durability of final products, resulting in improved performance and aesthetic value at reduced energy costs.
Similarly, in metallurgical processes, Sodium silicofluoride improves efficiency in aluminum refining and alloy production by facilitating impurity removal and reducing operational temperatures, which translates into energy savings and higher product quality.
Another benefit lies in its role as a chemical intermediate, where sodium silicofluoride provides a stable and accessible source of fluoride ions for the synthesis of other fluorine-based compounds.
This versatility supports downstream applications in sectors such as pharmaceuticals, advanced coatings, and specialty chemicals, enabling innovations in product development.
Sodium silicofluoride's historical and sometimes current use in pesticides, rodenticides, and wood preservatives underscores its effectiveness as a biocidal agent, helping protect crops, stored grains, and wooden structures from destructive pests.
In the construction industry, Sodium silicofluoride's inclusion in cement formulations and abrasives contributes to increased strength, resistance, and surface hardness, extending the longevity and durability of building materials and tools.
Importantly, sodium silicofluoride is also valued for its availability and relative affordability, making it accessible for both large-scale industrial operations and municipal treatment facilities.
High-purity grades offer additional benefits in electronics and pharmaceutical applications, where controlled release of fluoride ions is crucial for surface treatment, etching, or chemical synthesis.
These advanced applications highlight the adaptability of sodium silicofluoride, showing that while it has long served traditional industries, it continues to find relevance in modern, technology-driven fields.
In summary, the benefits of sodium silicofluoride can be framed in terms of public health protection, industrial efficiency, cost-effectiveness, and chemical versatility.
By improving dental health, enhancing material performance, reducing manufacturing costs, and supporting innovation in specialty sectors, sodium silicofluoride demonstrates its importance as a multifunctional compound.
These benefits, however, must always be weighed against Sodium silicofluoride's toxicity, reinforcing the need for careful management and regulatory oversight to ensure that its advantages are realized without undue risk.
Production of Sodium Silicofluoride:
Sodium silicofluoride is primarily produced as a by-product in the phosphate fertilizer industry, arising from the treatment of phosphate rock with sulfuric acid, a process that generates hydrofluosilicic acid (H₂SiF₆) as a side stream.
This hydrofluosilicic acid is the main precursor for sodium silicofluoride manufacture.
The most common industrial route involves the neutralization of hydrofluosilicic acid with sodium salts, such as sodium chloride (NaCl) or sodium carbonate (Na₂CO₃).
In one widely used method, hydrofluosilicic acid is reacted with sodium chloride, releasing hydrogen chloride gas and precipitating sodium silicofluoride crystals, which are then filtered, washed, and dried.
Alternatively, neutralization with sodium carbonate or sodium hydroxide leads to the formation of sodium silicofluoride and by-products like carbon dioxide or water.
The choice of raw material often depends on cost, availability, and purity requirements of the final product.
The process is generally conducted under controlled temperature and pH conditions to maximize yield and to prevent excessive hydrolysis of the fluorosilicate ion.
From a practical standpoint, crystallization and drying steps are crucial to obtaining a stable, free-flowing product suitable for industrial applications.
The resulting sodium silicofluoride typically appears as a white crystalline powder with purity levels ranging between 97% and 99%, though higher-grade products (≥99%) are manufactured for electronics, pharmaceuticals, and specialty uses.
Waste management is also an important aspect of production, as by-products like hydrogen chloride and residual fluorosilicate solutions must be handled in compliance with environmental and occupational safety regulations.
In some cases, advanced production facilities incorporate scrubbing systems and recycling loops to capture and reuse volatile fluorine compounds, improving both process efficiency and environmental sustainability.
Overall, the production of sodium silicofluoride reflects a balance between cost-efficient utilization of industrial by-products and the need for controlled processing and purification to meet diverse application requirements.
Sodium silicofluoride's origin as a by-product adds economic and environmental value by transforming what would otherwise be a waste stream from the fertilizer industry into a versatile industrial chemical.
Synthesis of Sodium Silicofluoride:
The synthesis of sodium silicofluoride is most commonly achieved through neutralization reactions involving hydrofluosilicic acid (H2SiF6), a by-product of the phosphate fertilizer industry.
Hydrofluosilicic acid is produced when fluorapatite-containing phosphate rock is treated with sulfuric acid, releasing volatile silicon tetrafluoride (SiF4), which reacts with water to form H2SiF6.
This intermediate compound provides the fluoride and silicate ions necessary for Na2SiF6 formation.
The general reaction for synthesis can be summarized as follows:
H₂SiF₆ + 2NaCl → Na₂SiF₆ ↓ + 2HCl ↑
In this route, hydrofluosilicic acid reacts with sodium chloride.
Sodium silicofluoride precipitates as a crystalline solid, while hydrogen chloride gas is released and must be captured by scrubbing systems to prevent atmospheric pollution.
Another common pathway uses sodium carbonate or sodium hydroxide as neutralizing agents:
H₂SiF₆ + Na₂CO₃ → Na₂SiF₆ ↓ + H₂O + CO₂ ↑
or
H₂SiF₆ + 2NaOH → Na₂SiF₆ ↓ + 2H₂O
These reactions are typically performed in aqueous solution, under controlled conditions of temperature, pH, and concentration, to optimize precipitation and avoid excessive hydrolysis of fluorosilicate ions.
The precipitated Na₂SiF₆ is then separated by filtration, washed to remove impurities, and dried to yield a stable, free-flowing white crystalline powder.
For high-purity grades (≥99%), additional purification steps such as recrystallization and multi-stage washing are employed to eliminate traces of unreacted salts or acidic residues.
Industrial processes also emphasize waste management, ensuring that by-products like CO₂, HCl, and spent liquors are either neutralized or recovered for reuse.
Manufacturing of Sodium Silicofluoride:
Sodium silicofluoride is made by neutralizing fluorosilicic acid with sodium chloride or sodium sulfate.
H2[SiF6] + 2 NaCl → Na2[SiF6] + 2 HCl
Natural Occurrence of Sodium Silicofluoride:
Sodium hexafluorosilicate occurs naturally as the rare mineral malladrite found within some volcanic fumaroles.
History of Sodium Silicofluoride:
The history of sodium silicofluoride is closely tied to the broader industrial use of fluorine compounds in the 19th and 20th centuries.
Although naturally occurring fluorosilicate minerals (such as malladrite, Na₂SiF₆) were known in small deposits, sodium silicofluoride as a manufactured product first emerged during the late 1800s, when chemists discovered methods to capture and convert fluorine-containing gases released from industrial processes.
At that time, the production of phosphate fertilizers using sulfuric acid began generating hydrofluosilicic acid (H₂SiF₆) as a waste by-product.
Instead of being discarded, this acid was eventually neutralized with sodium salts to form sodium silicofluoride, marking the compound’s introduction as a commercially useful material.
By the early 20th century, sodium silicofluoride had found application in the ceramics and glass industries, where it was valued as a flux and opacifier, improving glaze quality, durability, and resistance to chemical attack.
Around the same time, Sodium silicofluoride was also used in metallurgy, particularly in aluminum refining, where its fluoride content helped lower smelting temperatures and enhance process efficiency.
These uses established Sodium silicofluoride's reputation as a versatile industrial chemical.
A major milestone in its history occurred in the 1940s, when sodium silicofluoride began to be used in municipal water fluoridation programs.
Following research in the United States that linked fluoride exposure to improved dental health and reduced cavities, sodium silicofluoride—along with sodium fluoride and hydrofluosilicic acid—became one of the main chemicals adopted for adjusting fluoride levels in drinking water.
While effective and economical, Sodium silicofluoride's use sparked debate and controversy in later decades due to concerns about toxicity and long-term health effects of fluoride compounds, leading some regions to reduce or ban its use in water treatment, even as others continued to rely on it.
During the mid-20th century, sodium silicofluoride was also employed in agriculture and pest control, formulated into insecticides, rodenticides, and wood preservatives.
However, many of these applications declined in the late 20th century as stricter environmental and safety regulations restricted fluoride-based pesticides.
At the same time, sodium silicofluoride maintained its role in industrial chemistry as an intermediate for producing other fluorosilicate salts and fluorine-based compounds.
In more recent decades, the focus has shifted toward producing high-purity grades of sodium silicofluoride for advanced uses in electronics, pharmaceuticals, and specialty manufacturing, reflecting the chemical industry’s move toward precision materials and cleaner processes.
Additionally, modern production emphasizes sustainability, with efforts to recycle by-products like hydrofluosilicic acid from the fertilizer industry, thereby reducing waste and creating economic value from streams once considered pollutants.
Today, sodium silicofluoride stands as a compound with over a century of industrial use.
Sodium silicofluoride's history illustrates how a substance once regarded as an inconvenient by-product evolved into a multifunctional chemical used in water treatment, ceramics, metallurgy, and beyond.
At the same time, Sodium silicofluoride highlights the balance between utility and regulation, as societies weigh the benefits of fluoride applications against environmental and health concerns.
Handling and Storage of Sodium Silicofluoride:
Handle sodium silicofluoride in well-ventilated areas to avoid inhalation of dust.
Use appropriate local exhaust or general ventilation.
Avoid direct contact with skin, eyes, and clothing.
Do not eat, drink, or smoke while handling.
Wash thoroughly after use.
Store in tightly sealed, corrosion-resistant containers in a cool, dry, and well-ventilated area, away from moisture, strong acids, oxidizers, and foodstuffs.
Clearly label storage containers and keep them locked away from unauthorized personnel.
Stability and Reactivity of Sodium Silicofluoride:
Sodium silicofluoride is stable under normal conditions of storage and use.
Sodium silicofluoride decomposes upon heating, releasing toxic fluoride fumes.
In contact with moisture or strong acids, Sodium silicofluoride may liberate hydrofluoric acid (HF), which is highly corrosive.
Incompatible materials include strong acids, bases, oxidizing agents, and reactive metals.
Avoid conditions of high humidity and high temperature.
First Aid Measures of Sodium Silicofluoride:
Inhalation:
Move the exposed person to fresh air immediately.
If breathing is difficult, administer oxygen.
If not breathing, perform artificial respiration and seek medical attention.
Skin Contact:
Remove contaminated clothing.
Rinse skin with plenty of water and wash with soap for at least 15 minutes.
Seek medical advice if irritation persists.
Eye Contact:
Rinse cautiously with water for at least 15 minutes, lifting upper and lower eyelids.
Remove contact lenses if present and easy to do.
Seek immediate medical attention.
Ingestion:
Rinse mouth with water.
Do not induce vomiting.
Seek urgent medical help as ingestion may cause systemic fluoride poisoning (nausea, abdominal pain, hypocalcemia, convulsions).
Firefighting Measures of Sodium Silicofluoride:
Sodium silicofluoride is non-combustible, but in fire situations it can decompose to release toxic gases (fluorides, silicon oxides).
Use dry chemical powder, CO₂, foam, or water spray for surrounding fires.
Firefighters must wear self-contained breathing apparatus (SCBA) and full protective gear.
Contaminated firefighting water should be collected and disposed of as hazardous waste.
Accidental Release Measures of Sodium Silicofluoride:
Evacuate unnecessary personnel.
Ensure proper ventilation.
Wear full personal protective equipment (PPE) including respiratory protection.
Avoid generating dust.
Collect spilled material mechanically (e.g., sweep or vacuum with HEPA filter) and place in labeled, sealed containers for proper disposal.
Prevent entry into sewers, waterways, and soil.
Wash spill area with water while controlling runoff.
Exposure Controls / Personal Protection of Sodium Silicofluoride:
Occupational Exposure Limits:
Some jurisdictions set limits for fluoride compounds (e.g., TLV for fluorides ~2.5 mg/m³ as F⁻).
Engineering Controls:
Provide local exhaust ventilation to maintain airborne concentrations below limits.
Personal Protective Equipment (PPE):
Respiratory protection:
NIOSH-approved respirator if exposure limits may be exceeded.
Hand protection:
Chemical-resistant gloves (e.g., nitrile, neoprene).
Eye protection:
Safety goggles or face shield.
Skin/Body protection:
Protective clothing, lab coat or coveralls.
Hygiene Measures:
Wash hands, forearms, and face after handling; remove contaminated clothing and wash before reuse.
Identifiers of Sodium Silicofluoride:
CAS Number: 16893-85-9
ChemSpider: 26165
ECHA InfoCard: 100.037.198
EC Number: 240-934-8
PubChem CID: 28127
RTECS number: VV8410000
UNII: 806AV2E065
UN number: 2674
CompTox Dashboard (EPA): DTXSID9036933
InChI: InChI=1S/F6Si.2Na/c1-7(2,3,4,5)6;;/q-2;2*+1
Key: TWGUZEUZLCYTCG-UHFFFAOYSA-N
SMILES: [Na+].[Na+].F[Si--](F)(F)(F)(F)F
Linear Formula: Na2SiF6
Pubchem CID: 28127
MDL Number: MFCD00003491
EC No.: 240-934-8
IUPAC Name: disodium hexafluorosilicon(2-)
Beilstein/Reaxys No.: N/A
SMILES: [Na+].[Na+].F[Si-2](F)(F)(F)(F)F
InchI Identifier: InChI=1S/F6Si.2Na/c1-7(2,3,4,5)6;;/q-2;2*+1
InchI Key: TWGUZEUZLCYTCG-UHFFFAOYSA-N
Chemical Name: Sodium Silicofluoride
Molecular Formula: Na₂SiF₆
Molecular Weight: 188.06 g/mol
CAS Number: 16893-85-9
EC Number (EINECS): 240-896-2
UN Number (for transport): UN 2674
RTECS Number: VV9275000
InChI: InChI=1S/2Na.F6Si/c;;1-7(2,3,4,5)6/q2*+1;-2
InChI Key: JAFWZUDZJXYSSU-UHFFFAOYSA-L
PubChem CID: 24569
IUPAC Name: Disodium hexafluorosilicate
Properties of Sodium Silicofluoride:
Chemical formula: Na2[SiF6]
Molar mass: 188 g/mol
Appearance: white granular powder
Odor: odorless
Density: 2.7 g/cm3
Solubility in water: 0.64 g/100 mL (20 °C)
1.27 g/100 mL (50 °C)
2.45 g/100 mL (100 °C)
Solubility: insoluble in alcohol
Refractive index (nD): 1.312
Molecular Weight: 188.055 g/mol
Computed by PubChem 2.2 (PubChem release 2025.04.14)0
Hydrogen Bond Acceptor Count: 7
Rotatable Bond Count: 0
Exact Mass: 187.94688407 Da
Monoisotopic Mass: 187.94688407 Da
Topological Polar Surface Area: 0 Ų
Heavy Atom Count: 9
Complexity: 62.7
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 3
Compound Is Canonicalized: Yes
Chemical Formula: Na₂SiF₆
Molecular Weight: 188.06 g/mol
Appearance: White, odorless crystalline powder or granules
Odor: Odorless
Taste: Saline, slightly bitter
Density (specific gravity): ~2.68 g/cm³
Melting Point: Decomposes before melting (≈ 330–350 °C, releases toxic fluorides)
Boiling Point: Not applicable (decomposes on heating)
Solubility in Water: 0.41 g/100 mL at 25 °C (sparingly soluble)
Solubility in Alcohol: Insoluble
pH (aqueous solution): ~3.0–4.0 (slightly acidic due to hydrolysis)
Stability: Stable under dry, ambient conditions; decomposes in acids or strong heat
Reactivity: Reacts with strong acids to form hydrofluoric acid (HF); incompatible with strong bases and oxidizers
Vapor Pressure: Negligible (non-volatile solid)
Partition Coefficient (log Kow): Not applicable (ionic solid, not lipid soluble)
Crystal Structure: Hexagonal, occurs naturally as the mineral malladrite
Structure of Sodium Silicofluoride:
Crystal structure: trigonal
Space group: P321
Lattice constant:
a = 8.859, c = 5.038
Formula units (Z): 4
Related compounds of Sodium Silicofluoride:
Other cations:
Ammonium hexafluorosilicate
Fluorosilicic acid
Names of Sodium Silicofluoride:
Preferred IUPAC name:
Sodium fluorosilicate
Systematic IUPAC name:
Sodium hexafluoridosilicate(2–)
Other names:
Disodium hexafluorosilicate/sodium fluosilicate/sodium silicofluoride
