Precipitated silica

The production of precipitated silica starts with the reaction of a basic silicate solution with a mineral acid.

Sulfuric acid and sodium silicate solutions are added simultaneously with agitation to water.

The choice of agitation, duration of precipitation, the addition rate of reactants, their temperature and concentration and pH can vary the properties of the resulting silica.

The formation of a gel stage is avoided by stirring at elevated temperatures.

Primary structures typically have a diameter of 5 - 100 nm, and specific surface area 5–100 m2/g.