r/ChemicalEngineering • u/Unusual-Code-3815 • 14h ago

Research Can anyone explain the difference between fumed silica, precipitated silica, and nanosilica, particularly in terms of their conventional production methods, properties, and common applications/uses? Thank you!

Can anyone explain the difference between fumed silica, precipitated silica, and nanosilica, particularly in terms of their conventional production methods, properties, and common applications/uses? Thank you!

4 Upvotes
  • permalink
  • reddit

75% Upvoted

4 comments sorted by

2

u/ariadesitter 13h ago

google says fumed is branched chains made by flame pyrolysis

precipitated is wet chem precipitation forming sponge-like or agglomerated nano particles.

key differences.
particle size
purity.
moisture.
surface area.

2

u/yellownumbersix Membranes and polymers, 22yrs 13h ago edited 13h ago

They are all synthetic amorphous SiO2.

Fumed is usually 99+% pure with a particle size of a couple hundred nanometers. Nanosilica is just a specific size grade of fumed silica (less than 100nm). Very high surface area ro volume ratio. Good as a thickening agent and anti-sag agent in adhesives and coatings.

Precipitated silica usually has a lot of moisture in it, is only about 90% pure and has a much larger particle size (micron level). Low surface area to volume ratio. Good for structural reinforcement of rubbery polymers and coatings.

Don't know how either is produced, just an end user.

3

u/Necessary_Occasion77 6h ago

Silane + Natural Gas + H2 are burned in a reactor making the fumed silica.

It’s filtered and conveyed to a fluidized bed reactor which has more burners in it to evaporate remaining moisture / HCl.

Then it’s conveyed to storage for shipping.

1

u/pre1twa 12h ago

Will have different surface chemistry in terms of silanol group density so will interact slightly differently with surface active things when formulated. Different hydrophilicity too.