Silicas Technology

Precipitated silica is a silica (SiO2) produced by precipitation from a solution containing silicate salts.....

What's precipitated silica?

Precipitated silica is a silica (SiO2) produced by precipitation from a solution containing silicate salts.

Structure of Precipitated Silica sio2Physical and chemical properties
Property                   Result
Physical state            Solid
Form Powder          granules
Colour                    White
Melting point        > 1700°C
Flammability      Non flammable
Vapour pressure   Not applicable
Water solubility   Slightly soluble
 
Production
The production of precipitated silica starts with the reaction of an alkaline silicate solution with a mineral acid. Sulfuric acid and sodium silicate solutions are added simultaneously with agitation to water. Precipitation is carried out under alkaline conditions. The choice of agitation, duration of precipitation, the addition rate of reactants, their temperature and concentration, and pH can vary the properties of the silica. The formation of a gel stage is avoided by stirring at elevated temperatures. The resulting white precipitate is filtered, washed and dried in the manufacturing process.
Na2(SiO2)7 + H2SO4 → 3.3 SiO2 + Na2SO4 + H2O

Properties
The particles are porous. Primary particles with a diameter of 5 - 100 nm, and specific surface area 5-100 m2/g. Agglomeratesize is 1 - 40 um with average pore size is > 30 nm. Density: 1,9 - 2,1 g/cm3.

Applications
Filler, softener and performance improvement in rubber and plastics
Cleaning, thickening and polishing agent in toothpastes for oral health care
Food processing and pharmaceuticals additive as anti caking, thickening agent, absorbent to make liquids into powders.
Food rheology modifier
Defoamer


Please reference from  Wikipedia.org

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