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Pyrogenic silica is a high-purity, amorphous form of silicon dioxide (SiO₂) characterized by its extremely small particle size, high specific surface area, and highly reactive surface chemistry.
Pyrogenic silica is widely used as a performance-enhancing additive in paints, coatings, adhesives, elastomers, cosmetics, pharmaceuticals, and food products, where it provides thickening, thixotropic behavior, anti-settling, and reinforcement.
Produced via flame hydrolysis, pyrogenic silica forms lightweight, branched aggregates that offer exceptional rheological control and stability in both industrial and high-tech applications.
CAS Number: 112945-52-5
EC Number: 231-545-4
Molecular Formula: SiO₂
Molecular Weight: 60.08 g/mol
Synonyms: Cabosil, Cab-O-Sil®, Cab-O-Sil M5, Cab-O-Sil EH5, Cab-O-Sil LM150, Cab-O-Sil TS720, Fumed Silica, Pyrogenic Silica, Amorphous Silicon Dioxide, Synthetic Silica, Colloidal Silica (non-aqueous), Silicon Dioxide (amorphous, fumed), High Surface Area Silica, Hydrophilic Fumed Silica, Hydrophobic Fumed Silica, Nano-Silica (SiO₂), Aerosil®, HDK®, Tokusil, Fusil®, AEROSIL®, AEROSIL® 200, AEROSIL® 130, AEROSIL® 300, AEROSIL® R 972, AEROSIL® R 812, AEROSIL® R 202, AEROSIL® R 805, Fumed Silica, Pyrogenic Silica, Synthetic Amorphous Silica, Amorphous Silicon Dioxide, Colloidal Silica (non-aqueous), Nano Silica (SiO₂), High Surface Area Silica, Hydrophilic Fumed Silica, Hydrophobic Fumed Silica, Precipitated-Free Silica, Silica Thickener, Rheology Control Additive, Fumed Silica, Pyrogenic Silica, Amorphous Silica, Synthetic Amorphous Silica (SAS), Colloidal Silica (non-aqueous), Silicon Dioxide (SiO₂) (amorphous form), Ultrafine Silica, Nano Silica, High Surface Area Silica, Non-Porous Silica, Silica Nanoparticles (amorphous), Silica Thickener, Rheology Modifier (Silica), Hydrophilic Fumed Silica, Hydrophobic Fumed Silica, Cab-O-Sil®, AEROSIL®, HDK®, Tokusil®, Fusil®
Pyrogenic silica is a high-purity, ultrafine amorphous form of silicon dioxide (SiO₂) produced through the flame hydrolysis of silicon tetrachloride in a hydrogen-oxygen flame.
This process results in extremely small, non-porous, and highly dispersed spherical particles with a large surface area and low bulk density.
Pyrogenic silica appears as a white, odorless, fluffy powder and is insoluble in water, but dispersible in many solvents and polymers.
Due to its high surface energy and ability to form three-dimensional networks, it exhibits excellent thickening, anti-caking, thixotropic, and reinforcing properties.
Pyrogenic silica is widely used as a performance-enhancing additive in applications such as paints, coatings, adhesives, sealants, elastomers, cosmetics, pharmaceuticals, and food products.
In addition, pyrogenic silica plays a crucial role in thermal insulation, battery electrolytes, and silicone rubber compounding, making it indispensable in industries that demand precise rheological control, improved mechanical strength, or enhanced stability.
Pyrogenic silica's unique combination of chemical inertness, thermal resistance, and multifunctional behavior makes pyrogenic silica a highly valued material in both industrial and high-tech formulations.
Pyrogenic silica is the name for a range of amorphous fumed silica products made by Cabot Corporation.
The molecular structure of Pyrogenic silica consists of nanometre droplets of amorphous silica fused into branched chains.
They are characterised by high purity, low bulk density and submicron particle size.
Pyrogenic silica is a medium surface area fumed silica which imparts a significant increase in viscosity to liquid systems, free flow of powders and reinforcement of silicone and organic rubbers.
Pyrogenic silica is a medium surface area fumed silica which has been surface modified with polydimethylsiloxane.
The treatment renders Pyrogenic silica extremely hydrophobic, with very different properties to untreated silica grades like M5.
Pyrogenic silica is a extremely light powder used as a resin thickener it is ideal for vertical surfaces to avoid sags and run-off.
Pyrogenic silica is a light, fluffy powder that is white in appearance and is used in many applications in the surf industry.
Pyrogenic silica is a thixotropic paste designed to give resin vertical hanging capabilities.
Pyrogenic silica works very well with epoxy and polyester/vinylesters.
Pyrogenic silica has a clear appearance when mixed.
Pyrogenic silica is an epoxy thickening agent for resins and gel coats.
Pyrogenic silica stands as utra light white powder.
Pyrogenic silica is a high-purity, non-crystalline silica produced via flame hydrolysis, consisting of discrete submicron silica spheres fused into branched aggregates.
Pyrogenic silicacrystalline‑free, hydrophilic, with extremely high surface area—ideal for rheological control, thickening and stabilizing in diverse industrial systems.
Pyrogenic silica is a synthetic, amorphous, colloidal silicon dioxide that is generally regarded as unique in industry because of its unusual particle characteristics.
Pyrogenic silica’s extremely small particle size, its enormous surface area, its high purity, and its chain-forming tendencies set it apart in a class of its own.
Pyrogenic silica is a light, fluffy powder that is white in appearance and is used in many applications and a variety of industries.
Pyrogenic silica is a untreated medium surface fumed silica that provides thickening, thixotrophic, and anti-settling behavior in liquid systems.
Pyrogenic silica is most efficient in non-polar to medium polarity systems, and provides increases in hardness, tensile strength and elongation.
Pyrogenic silica can be used for reinforcement of silicone and organic rubbers.
Pyrogenic silica is well suited for use in coatings, adhesives, and other liquid systems.
Pyrogenic silica is a medium surface fumed silica used in adhesives.
Pyrogenic silica provides thickening, thixotrophic (shear thinning), and anti-settling behavior in liquid systems.
Pyrogenic silica untreated fumed silica is a synthetic, amorphous, colloidal silicon dioxide that is generallyregarded as unique in industry because of its unusual particle characteristics.
Pyrogenic silica’s extremely small particle size, its enormous surface area, its high purity, and its chain-forming tendencies set it apart in a class of its own.
Pyrogenic silica is a light, fluffy powder that is white in appearance and is used in many applications and a variety of industries.
Pyrogenic silica is a medium surface fumed silica which enables a significant increase in viscosity in liquid systems, free flow of powders and reinforcement of silicone and organic rubbers.
Pyrogenic silica is most efficient in non-polar to medium polarity systems and offers an excellent balance of thickening efficiency and dispersibility.
Key characteristics of Pyrogenic silica include high purity, aggregated structure, submicron particle size, low bulk density and hydrophilic surface.
Pyrogenic silica is medium surface fumed silica.
Pyrogenic silica is widely used to provide thickening, thixotrophic (shear thinning), and anti-settling behavior in liquid systems.
Pyrogenic silica is most efficient in non-polar to medium polarity systems.
Pyrogenic silica is Fumed silica powder and is used as a thickening agent for resins.
Pyrogenic silica can be added to polyurethane, polyester, vinylester or epoxy resins to increase viscosity.
Pyrogenic silica is a very fine powder and easily airborne so a dust mask should be worn when using it.
Pyrogenic silica is a thixotropic agent which prevents sagging or dropping of resin when applied on vertical surfaces.
Pyrogenic silica is also ideal to use as a thickener with Pros-aide to create transfers.
This is the thixotrope which makes the resin and gelcoat non drip, thixotropic resins will have between 0.75 - 1% by weight included in the formulation and gelcoats around 2.5% .
Pyrogenic silica is a thixotrope which when added to resin and gelcoat will make them non drip.
Pyrogenic silica is a high-purity, amorphous form of silicon dioxide (SiO₂) characterized by its extremely small particle size, high specific surface area, and highly reactive surface chemistry.
Pyrogenic silica is synthesized through the flame hydrolysis process, where silicon tetrachloride (SiCl₄) is reacted with hydrogen and oxygen at high temperatures in a flame, resulting in the formation of tiny, spherical silica particles that fuse into branched, chain-like aggregates.
These aggregates are collected as a white, fluffy, odorless powder with very low bulk density and exceptional surface energy.
Unlike crystalline silica, pyrogenic silica is non-porous, chemically inert, and insoluble in water, but disperses well in a variety of organic solvents, oils, and polymer systems.
The unique physical properties of pyrogenic silica—such as its ability to create three-dimensional particle networks—make it a highly effective rheology modifier, anti-caking agent, thickener, and reinforcing filler.
Pyrogenic silica is widely used in industries including paints and coatings, adhesives and sealants, elastomers, cosmetics, pharmaceuticals, and food.
In these formulations, Pyrogenic silica helps to prevent sedimentation, control viscosity, enhance mechanical strength, and stabilize emulsions.
In high-tech applications, pyrogenic silica plays a critical role in lithium-ion batteries, aerogels, thermal insulation materials, and optical fiber manufacturing, where precise particle control and thermal stability are essential.
Pyrogenic silica also contributes to improved performance in silicone rubbers by increasing tear resistance and dimensional stability.
Due to Pyrogenic silica's nano-scale structure and high surface reactivity, pyrogenic silica must be handled with appropriate safety measures, especially in dry powder form, to avoid inhalation and dust exposure.
Nevertheless, Pyrogenic silica's chemical stability, thermal resistance, and multifunctional performance make it a vital material in both everyday consumer products and advanced industrial technologies.
Market Overview of Pyrogenic Silica:
Pyrogenic silica is a high-purity, nanostructured material widely used across a range of industries due to its exceptional surface area, particle-size control, and thixotropic behavior.
The global market for pyrogenic silica is witnessing steady growth, driven by increasing demand in coatings, adhesives, sealants, elastomers, pharmaceuticals, cosmetics, and battery technologies.
One of the primary growth sectors is the automotive and construction industries, where fumed silica is used to enhance rheology, improve mechanical strength, and prevent sagging or settling in coatings and sealants.
In the electronics and energy sector, particularly with the rise of lithium-ion batteries, fumed silica is gaining attention as a performance additive in thermal interface materials and battery slurries due to its thermal and electrical insulation properties.
The Asia-Pacific region, led by China, dominates global consumption, owing to rapid industrialization, expanding infrastructure, and growing manufacturing activities.
Meanwhile, developed regions such as North America and Europe maintain stable demand, especially in high-end applications like pharmaceuticals, personal care products, and food-grade formulations where pyrogenic silica acts as an anti-caking agent, carrier, or viscosity enhancer.
The market is also benefiting from increasing global trends toward sustainability, as fumed silica enables low-VOC and environmentally friendly formulations in paints and coatings.
However, the industry faces challenges such as high energy costs for production, volatility in raw material pricing, and tightening environmental regulations related to nanoparticle handling and occupational safety.
Additionally, competition from alternative materials such as precipitated silica, clay-based thickeners, or organic rheology modifiers presents cost-performance trade-offs that may impact adoption in certain segments.
Nevertheless, with expanding applications in green technologies, EVs, and specialty chemicals, the future of the pyrogenic silica market appears robust, supported by technological advancements and a consistent need for high-performance multifunctional additives across global industries.
Uses of Pyrogenic Silica:
Pyrogenic silica is used Aerosil filler for epoxy and polyester resin.
Pyrogenic silica finds practical use in several key applications, such as: Securing fin boxes with precision, Enhancing the viscosity of epoxy tints, Effectively repairing dings and blemishes, Reinforcing boards against unexpected breakages.
Pyrogenic silica increases anti-corrosive qualities in resins
Pyrogenic silica improves compressive strength
Pyrogenic silica disallows settling of particles (like glitter) in resin systems
Pyrogenic silica, on the other hand causes the resin to have increased internal cohesive forces.
In low quantities, Pyrogenic silica causes the resin not to sag or run.
In higher concentrations, Pyrogenic silica causes the resin to get thicker and more like a paste.
If you mix in a cup, you will inevitably entrap air and the resulting paste will turn white.
If you heat the resin (<100°F) and apply a vacuum, you can get the resin to make a clear, jelly-like colloidal.
A thixotropic agent which prevents sagging or dropping of resin when applied on vertical surfaces.
Also ideal to use as a thicken with Pros-aide to create a creamy formula which helps prevent any dripping.
An extremely fine powder, Pyrogenic silica, used to thicken virtually every liquid material.
Pyrogenic silica is typically used to thicken resin, paint, dyes, and even water.
Pyrogenic silica is great for making fillet putty, thickening epoxy for a better glue consistency.
Milled Glass Fibers can produce a high strength non-sagging structural adhesive.
3M Glass Bubbles produce an easy spreading and sanding faring compound.
Pyrogenic silica can contribute to difficulties in sanding.
Where sanding will follow, use only as much Pyrogenic silica as is required to impart thixotrophy.
Pyrogenic silica can be used for: Installing fin boxes, Thickening up tints for epoxy, Solid ding repairs, Board snaps.
Pyrogenic silica is light weight, low density fumed silica powder additive for use in all types of Resins and Gelcoats although, when used to thicken polyester or vinylester resins, creates an excellent medium sanding, non-slumping compound.
Pyrogenic silica is an extremely fine powder used to thicken virtually every liquid material.
Pyrogenic silica is typically used to thicken resin, paint, dyes, and even water.
Pyrogenic silica is great for making fillet putty, thickening epoxy for a better glue consistency, and for use below the waterline.
Pyrogenic silica is a thickening agent for epoxies, polyesters, and urethanes.
Thicken resins to your own liking by adding varying amounts for gap filling, to reduce running and sagging, and making resin glue.
Pyrogenic silica is ideal for making adhesives and putties for gluing wood, fiberglass, stone, concrete, etc.
However, adding Pyrogenic silica will make the cured resin a bit more difficult to sand.
Pyrogenic silica is typically used in surfboard construction for leash plug and finbox installs to reduce the amount of resin draining into the foam and also increase the bond strength to the fin box or plug.
Pyrogenic silica can be added to epoxy resin to seal EPS blanks for additional strength.
Recommended Use of Pyrogenic Silica: Rheological control; Flow agent; Anti-caking agent; Anti-blocking agent; Anti-settling agent; Spray aid; Thickening agent; Carrier; Viscosity control agent; Glossing or matting agent; Chemical intermediate; Stabilization agent; Filler; Reinforcing agent in: Coatings.
Pyrogenic silica is used Adhesives, Sealants, Silicone Elastomer, Rubber products, Suspension, Dispersion, Batteries, Cosmetics,
Inks and toners, Paints, Hygiene and sanitary products.
Pyrogenic silica is used around the world to meet challenging performance requirements.
Due to its unique particle characteristics, Pyrogenic silica provides superior performance benefits for many types of applications, including:
Adhesives and sealants, Agriculture and lawn care, Chemical mechanical planarization (CMP), Coatings, Composites, Food additives, Greases, Pharmaceuticals, Printing and packaging, Silicone sealants, Skin and beauty care products, and Performance benefits.
Pyrogenic silica is used cosmetics & hygiene products (technical grade, caution for pharma use disclaimers).
Pyrogenic silica is used Powder flow agent, spray aid, anti-settling and anti-caking agent in many manufacturing sectors.
Pyrogenic silica is an extremely light powder used as a resin thickener it is ideal for vertical surfaces to avoid sags and run-off.
Pyrogenic silica is recommended no more than 1/2 part filler to 1 part of resin.
Pyrogenic silica is used Adhesives & Sealants, Coatings, Foods, Cosmetics, Composites.
Pyrogenic silica offers an excellent balance of thickening efficiency and dispersibility.
Pyrogenic silica exhibits high purity, aggregated structure, submicron particle size, low bulk density and hydrophilic surface chemistry.
When blended into sticky and poorly flowing powder systems, Pyrogenic silica reduces the angle of repose and improves powder flow.
Pyrogenic silica can be used as a rheology control additive in all resin systems, when hydrophobicity and shelf stability are of only moderate concern.
Pyrogenic silica can also be used as a thickener in Pros-Aide or Pro-Key to produce transfers.
Pyrogenic silica is a thixotrope which when added to resin and gelcoat will make them non drip.
Pyrogenic silica can also be used as a thickener in Pros-Aide or Pro-Key to produce transfers.
Pyrogenic silica is not easy to disperse without a mechanical stirrer, you can mix by hand, however it will not develop its full effect if not completely mixed.
Pyrogenic silica should be used with personal safety equipment at all times.
Pyrogenic silica is an extremely fine powder used to thicken virtually every liquid material.
Pyrogenic silica is typically used to thicken resin, paint, dyes, and even water.
Pyrogenic silica is an extremely fine powder used to thicken virtually every liquid material.
Pyrogenic silica is typically used to thicken resin, paint, dyes, and even water.
Pyrogenic silica is great for making fillet putty, thickening epoxy for a better glue consistency, and for use below the waterline.
Pyrogenic silica is an ideal product for repairing the blisters that are so common on fiberglass boats.
Pyrogenic silica is also mixed with Milled Fiber for structural putty and or microspheres (Q-Cells) for sandable putty.
Pyrogenic silica is used in approximately a 1:1 ratio to the mixed resin by volume.
Function of Pyrogenic Silica:
Pyrogenic silica provides thixotropic rheology control, stabilizer, anti-settling, anti-caking agent.
Pyrogenic silica increases viscosity, prevents phase separation or settling in suspensions, coatings, adhesives.
Pyrogenic silica enhances flowability in powders; serves as a reinforcing filler in polymers and silicone rubbers.
Pyrogenic silica is used as matting or bulking agent in finishes and varnishes.
The incorporation of Pyrogenic silica in polyesters is a function of a number of variables.
Several of the variables that can have an influence on the performance of the dispersion are:
Grade of Pyrogenic silica
Concentration of Pyrogenic silica
Dispersion condition (intensity, equipment, etc.)
Resin chemistry and molecular weight distribution
Styrene concentration
Free glycol content
Nature of the other additives used in a polyester resin formulation
Among the more predictable effects are those of silica grade, silica loading and dispersion conditions.
The differences in behavior imposed by the resin chemistry and the presence of additives are complex, often making Pyrogenic silica impossible to draw any general conclusions.
All of these factors should be considered when setting viscosity specifications for a particular product.
Benefits of Pyrogenic Silica:
High purity
Aggregated structure
Submicron particle size
Low bulk density
Hydrophilic surface
Synthesis of Pyrogenic Silica:
Pyrogenic silica is synthesized via a high-temperature gas-phase process called flame hydrolysis.
This method involves the reaction of volatile silicon compounds, typically silicon tetrachloride (SiCl₄), in a hydrogen–oxygen flame.
The process occurs at extremely high temperatures (around 1000–1200°C) and produces amorphous, nanostructured silica particles with a very high specific surface area and extremely low bulk density.
Main Reaction Steps:
Flame Hydrolysis of Silicon Tetrachloride:
The core chemical reaction involves the hydrolysis and oxidation of SiCl₄:
SiCl₄ (g)+2H₂ (g)+O 2(g)→SiO₂ (s)+4HCl (g)
Silicon tetrachloride vapor is introduced into a hydrogen–oxygen flame, where it reacts with moisture or hydrogen and oxygen to form silicon dioxide (SiO₂).
Hydrochloric acid (HCl) is generated as a by-product in the gas phase and removed via scrubbing systems.
Particle Formation and Collection:
The SiO₂ formed in the flame nucleates into primary spherical particles with diameters typically between 5–50 nm.
These primary particles rapidly aggregate into branched, chain-like structures, forming the characteristic three-dimensional fumed silica morphology.
The aggregates are collected in a filter or cyclone separator, forming a white, fluffy, odorless powder with high surface area (typically 100–400 m²/g).
Production of Pyrogenic Silica:
Pyrogenic silica is produced through a high-temperature gas-phase process called flame hydrolysis, which involves the reaction of silicon tetrachloride (SiCl₄) with hydrogen and oxygen in a flame at temperatures exceeding 1000 °C.
In this process, the volatile silicon compound undergoes hydrolysis and oxidation, forming ultra-fine, amorphous silicon dioxide (SiO₂) particles and releasing hydrogen chloride (HCl) as a gaseous by-product.
The resulting primary silica particles, typically between 5 to 50 nanometers in size, spontaneously fuse into branched, chain-like aggregates, which are collected as a light, fluffy, white powder with extremely high surface area.
This unique morphology gives pyrogenic silica its exceptional thickening, reinforcing, and thixotropic properties.
After formation, Pyrogenic silica may undergo surface treatment—such as with silanes or siloxanes—to adjust hydrophobicity or chemical compatibility for specific applications.
The entire production process requires precise control of temperature, gas flow, and collection systems, and includes scrubbing systems to safely capture and neutralize the hydrogen chloride emissions.
Due to the nanoscale nature of the material, proper containment and ventilation are essential during handling to minimize health and environmental risks.
History of Pyrogenic Silica:
The history of pyrogenic silica, dates back to the mid-20th century, emerging as a key innovation during the rapid development of synthetic materials and high-performance additives.
Pyrogenic silica was first developed in the 1940s by the German chemical company Degussa AG (now part of Evonik Industries) in response to the need for reinforcing agents in silicone rubber production, which was becoming increasingly important for military and aerospace applications during and after World War II.
The foundational breakthrough was the discovery of the flame hydrolysis process, a method that produces ultrafine, amorphous silica particles by burning silicon tetrachloride (SiCl₄) in a hydrogen–oxygen flame.
This technique allowed for the production of extremely pure and finely controlled silica powders with unique properties such as high surface area, low bulk density, and the ability to modify rheological behavior in liquid systems.
The resulting material, pyrogenic silica, was initially applied to enhance the mechanical strength of silicone elastomers, and its usefulness rapidly extended to paints, coatings, adhesives, and cosmetics throughout the 1950s and 1960s.
In the 1960s and 70s, as polymer and composite materials advanced, the demand for reinforcing fillers and thixotropic agents grew, pushing the expansion of pyrogenic silica production across Europe, the United States, and Japan.
Companies like Cabot Corporation (USA), Wacker Chemie (Germany), and Tokuyama Corporation (Japan) entered the market, refining the technology and broadening its application base.
By the 1980s and 1990s, the rise of electronics, semiconductors, and automotive coatings created new demand for pyrogenic silica in high-purity applications, such as insulators, optical fibers, and thermal interface materials.
Pyrogenic silica's ability to serve as a free-flow agent and anti-caking additive also led to adoption in food processing and pharmaceuticals.
In recent decades, the rise of nanotechnology, green chemistry, and advanced energy storage—particularly lithium-ion batteries and aerogels—has positioned pyrogenic silica as a vital component in emerging technologies.
Modern production methods have become more environmentally efficient, with tighter controls on particle size distribution, purity, and surface treatment.
Today, pyrogenic silica is recognized as one of the most important nanostructured industrial materials, with global production led by multinational companies serving industries ranging from everyday consumer products to advanced aerospace systems.
Handling and Storage of Pyrogenic Silica:
Safe Handling:
Avoid generating or inhaling dust.
Use only in well-ventilated areas or under a local exhaust system.
Avoid contact with eyes and prolonged skin exposure.
Ground equipment to prevent static discharge when transferring powder.
Do not eat, drink, or smoke when handling.
Storage Conditions:
Store in a cool, dry, well-ventilated place.
Keep containers tightly closed and protected from moisture.
Avoid conditions that may cause dust accumulation or electrostatic buildup.
Keep away from incompatible materials (e.g., strong oxidizers if surface-treated).
Stability and Reactivity of Pyrogenic Silica:
Chemical Stability:
Stable under normal ambient conditions.
Non-reactive under normal use; retains structure over time.
Conditions to Avoid:
High humidity (can lead to clumping or caking).
Strong electrostatic charges.
Open flames or ignition sources if surface-treated with combustible organics.
Incompatible Materials:
Strong oxidizing agents (especially with hydrophobic grades).
Hydrofluoric acid (reacts violently with silica).
Hazardous Decomposition Products:
None under normal conditions.
Surface-treated (hydrophobic) grades may release carbon oxides if burned.
First Aid Measures of Pyrogenic Silica:
Inhalation:
Move to fresh air.
Seek medical attention if coughing or difficulty breathing occurs.
Skin Contact:
Wash skin with soap and water.
Seek help if irritation persists.
Eye Contact:
Rinse cautiously with water for several minutes.
Remove contact lenses if present.
Ingestion:
Rinse mouth with water.
Do not induce vomiting.
Seek medical advice if symptoms appear.
Firefighting Measures of Pyrogenic Silica:
Suitable Extinguishing Media:
Water spray, foam, dry chemical, or carbon dioxide (CO₂).
Fire Hazards:
Not flammable in hydrophilic (untreated) form.
Hydrophobic grades may contain combustible surface treatments.
Protective Equipment for Firefighters:
Wear self-contained breathing apparatus (SCBA).
Use full protective clothing.
Avoid inhalation of decomposition gases from treated silica (e.g., CO, CO₂).
Accidental Release Measures of Pyrogenic Silica:
Personal Precautions:
Avoid dust formation.
Use personal protective equipment (PPE) to prevent inhalation and contact.
Evacuate area if large quantities are released into the air.
Cleanup Methods:
Vacuum using HEPA filters or damp sweep.
Avoid dry sweeping, which may generate airborne dust.
Place waste in labeled, sealed containers for disposal.
Environmental Precautions:
Avoid discharge into water systems.
Not expected to pose serious environmental risk, but control releases.
Exposure Controls / Personal Protective Equipment of Pyrogenic Silica:
Engineering Controls:
Use local exhaust ventilation or dust collection systems.
Enclose transfer systems if possible.
Use explosion-proof equipment in the case of surface-treated grades.
Personal Protective Equipment
PPE Type: Recommended Protection:
Respiratory:
Dust mask or NIOSH-approved respirator (N95 or higher) for airborne dust
Eye:
Safety goggles or full-face shield
Skin/Hands:
Gloves (nitrile or rubber), long sleeves to prevent skin exposure
Body:
Antistatic clothing in dusty environments
Identifiers of Pyrogenic Silica:
Chemical Name: Synthetic Amorphous Silica
Formula: SiO2
Molecular Weight: 60.08 g/mol
CAS Number: 112945-52-5 (specific to Cab-O-Sil); more generally 7631-86-9
EC Number: 262-373-8 (specific); more generally 231-545-4
MDL Number: MFCD00011232
Chemical Name: Silicon dioxide (amorphous)
Common Name: Pyrogenic silica / Fumed silica
IUPAC Name: Silicon dioxide
Molecular Formula: SiO₂
Molecular Weight: 60.08 g/mol
Appearance: White, odorless, fluffy powder
Physical Form: Amorphous, non-porous, nano-sized particles
CAS Number: 112945-52-5 (most common for fumed silica)
Alternate CAS Numbers: 7631-86-9 (general for synthetic amorphous silica)
EC Number (EINECS): 231-545-4
UN Number: Not classified as hazardous for transport
PubChem CID: 24261 (general SiO₂)
ChemSpider ID: 22644 (general for silicon dioxide)
RTECS Number: VV7310000
REACH Registration: Registered under EU REACH
SMILES: [Si](=O)(=O)
InChI: 1S/O2Si/c1-3-2
InChIKey: VYPSYNLAJGMNEJ-UHFFFAOYSA-N
Molecular Shape: Amorphous (non-crystalline, no long-range order)
Particle Size: Typically 5–50 nm (primary particles)
Surface Area (BET): 100–400 m²/g (varies by grade)
Properties of Pyrogenic Silica:
Appearance: White, dry powder; fine powder
Density / Specific Gravity: ~2.2g/cm³ @ 20 °C; bulk density approx. 40 g/L (~0.04g/cm³)
Melting Point: ~1,700°C; 1,719°C
Boiling / Sublimation Point: ~2,230°C
pH (4% aqueous solution): ~3.6–4.5
Water Solubility: Slightly soluble / practically insoluble under most conditions (OECD 105)
Particle Size:
Primary particles: ~5–50nm
Aggregates: Micron-sized branched structures
BET Surface Area:
Typical: ~170–230m²/g
Range (depending on grade): 200–390m²/g
Chemical Name: Silicon dioxide (amorphous)
Common Name: Fumed silica / Pyrogenic silica
Chemical Formula: SiO₂
Molar Mass: 60.08 g/mol
CAS Number: 112945-52-5 (for pyrogenic form)
Appearance: White, odorless, amorphous powder
Physical State: Solid (powder)
Crystallinity: Amorphous (non-crystalline)
Primary Particle Size: ~5–50 nanometers
Agglomerate Size: Up to several microns (depends on handling)
Surface Area (BET): 100–400 m²/g (grade-dependent)
Density (Bulk): ~30–60 kg/m³ (very low; fluffy)
Density (True): ~2.2 g/cm³
pH (4% in water): ~3.6–4.5 (slightly acidic)
Solubility in Water: Insoluble
Solubility in Solvents: Dispersible in some solvents/oils, not soluble
Melting Point: ~1,710 °C
Boiling Point: Sublimes (no defined boiling point)
Refractive Index: ~1.46
Thermal Conductivity: Low (acts as an insulator)
Combustibility: Non-flammable
Electrical Conductivity: Electrically insulating
Hygroscopicity: High surface moisture adsorption capacity
Surface Reactivity: High – due to silanol groups (–SiOH)
Surface Modification (optional): Can be hydrophilic or hydrophobic (via surface treatment)
