What is Colloidal Silicon Dioxide CAS 7631-86-9?

Colloidal Silicon Dioxide CAS 7631-86-9 is an amorphous, submicroscopic synthetic silica also known as fumed silica or pyrogenic silica. It has the molecular formula SiO2 and molecular weight 60.08 g/mol, and is supplied as a very low-density white powder.

How does Colloidal Silicon Dioxide differ from precipitated silica?

Colloidal or fumed silica is produced by flame hydrolysis and normally has a finer primary particle size, lower bulk density, and stronger glidant and thixotropic effects. Precipitated silica is made by a wet precipitation process from silicate solution and usually has different moisture content, bulk density, and handling behavior.

Why is Colloidal Silicon Dioxide used in tablet manufacturing?

It acts as a glidant and anti-caking agent, typically at 0.1% to 1.0%, to improve powder flow into tablet dies and support uniform weight. This helps reduce sticking, capping, and fill-weight variation during high-speed tableting.

What food and industrial applications is this grade suitable for?

Food-grade colloidal silicon dioxide is used as an anti-caking agent, carrier, and defoaming aid. Industrial grades are used in coatings, adhesives, paints, inks, and silicone rubber for thickening, thixotropy, anti-settling, and reinforcement.

What key specifications should a buyer confirm for Colloidal Silicon Dioxide?

The most important values are silica assay on an ignited basis, BET specific surface area, pH of an aqueous dispersion, loss on drying, loss on ignition, tapped density, and heavy-metal or arsenic limits. The standard hydrophilic grade in this product listing has a BET surface area around 200 m2/g.

Colloidal Silicon Dioxide CAS 7631-86-9

Colloidal Silicon Dioxide, CAS 7631-86-9, also known as fumed silica, is an amorphous synthetic silica supplied for pharmaceutical, food, cosmetic and industrial applications. Confirm the required grade and specification, then request a quotation with COA/TDS/SDS for bulk supply.

CAS: 7631-86-9
Synonyms: Fumed Silica, Pyrogenic Silica, Amorphous Silicon Dioxide, SiO2, Silica aerogel, Synthetic Amorphous Silica (SAS)
Einecs: 231-545-4
Molecular Formula: SiO₂
Grade: Pharmaceutical Grade / Food Grade / Industrial Grade
Package: 10kg/Multi-layer paper bag (Due to low bulk density, standard packaging is 10kg, not 25kg).

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Product Description

Colloidal Silicon Dioxide, CAS 7631-86-9, also called fumed silica, is an amorphous synthetic silica.

Synonyms: Fumed Silica; Pyrogenic Silica; Amorphous Silicon Dioxide; SiO2; Silica aerogel; Synthetic Amorphous Silica (SAS).

CAS: 7631-86-9.

It has the molecular formula SiO2 and molecular weight 60.08 g/mol.

It appears as a fluffy white powder with a very low bulk density.

It has a BET specific surface area of about 200±25 m²/g and an assay of at least 99.8% on an ignited basis.

It is highly hygroscopic and must be stored sealed in a cool, dry place.

It acts as a glidant and anti-caking agent to improve powder flow.

It is used in tablet manufacturing and capsule filling at about 0.1–1.0%.

It builds viscosity and thixotropy in creams, gels, paints and adhesives.

It is used in toothpaste as an abrasive and thickener, and in face powders to prevent caking.

It is used as food anti-caking agent E551 in spices, powdered milk and coffee creamers.

It reinforces silicone rubber and improves tear strength.

It prevents sagging and pigment settling in paints and coatings.

Confirm appearance, BET surface area, assay, pH, loss on drying, ignition loss, tamped density, heavy metals, arsenic and grit.

Store sealed in a cool, dry place, keep pallets off the floor, and reseal immediately after use.

Confirm packaging with the requested quantity and destination requirements.

The page is an RFQ entry point and does not state stock, price, MOQ or fixed lead time.

For an RFQ, state the intended use, required grade and specification, quantity, packaging, destination and document needs.

FAQ - Technical & Supply Chain

Q:
What is Colloidal Silicon Dioxide CAS 7631-86-9?

A: Colloidal Silicon Dioxide CAS 7631-86-9 is an amorphous, submicroscopic synthetic silica also known as fumed silica or pyrogenic silica. It has the molecular formula SiO2 and molecular weight 60.08 g/mol, and is supplied as a very low-density white powder.
Q:
How does Colloidal Silicon Dioxide differ from precipitated silica?

A: Colloidal or fumed silica is produced by flame hydrolysis and normally has a finer primary particle size, lower bulk density, and stronger glidant and thixotropic effects. Precipitated silica is made by a wet precipitation process from silicate solution and usually has different moisture content, bulk density, and handling behavior.
Q:
Why is Colloidal Silicon Dioxide used in tablet manufacturing?

A: It acts as a glidant and anti-caking agent, typically at 0.1% to 1.0%, to improve powder flow into tablet dies and support uniform weight. This helps reduce sticking, capping, and fill-weight variation during high-speed tableting.
Q:
What food and industrial applications is this grade suitable for?

A: Food-grade colloidal silicon dioxide is used as an anti-caking agent, carrier, and defoaming aid. Industrial grades are used in coatings, adhesives, paints, inks, and silicone rubber for thickening, thixotropy, anti-settling, and reinforcement.
Q:
What key specifications should a buyer confirm for Colloidal Silicon Dioxide?

A: The most important values are silica assay on an ignited basis, BET specific surface area, pH of an aqueous dispersion, loss on drying, loss on ignition, tapped density, and heavy-metal or arsenic limits. The standard hydrophilic grade in this product listing has a BET surface area around 200 m2/g.

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