Precipitated Silica

We supply a wide range of Precipitated Silica, which is used for strengthening polymers, in rubber and elastomer, in powdered foodstuffs, pharmaceutical formulations etc. Our Precipitated Silica is also used as carriers, fillers, coating agents or for improving mechanical properties of the end product.

Precipitated silica is a silica (SiO₂) produced by precipitation from a solution containing silicate salts. 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 + H_2O
Physico Chemical Characteristics of Precipitated Silica

• BET Surface area : Brunauer, Emmett and Teller developed the process of calculating the surface area of precipitated silica. This method of calculating the surface area is popularly known as BET surface area.

• PH value : The pH value of precipitated silica is generally in neutral range. It is determined electrometrically with a glass electrode and pH meter.

• Drying loss : There is very small amount of physically bonded water content in precipitated silica. The major part of this water content is removed by drying in drying cabinet at 105oC for 2 hours.

• Ignition Loss : Precipitated silica contains chemically bonded water in the form silanol groups is also removed after 2 hours of ignition time at 1000oC. The ignition loss is determined with the substance that has previously been dried for 2 hours at 105ËšC.

• SiO₂ content : Silicon dioxide content is determined gravimetrically by fuming off with hydrofluoric acid. The sulphate and chloride contents are determined by potentiometric titration.

• SIEVE residue. : SIEVE residue is determined by using Mocker apparatus. In this process the silica suspension is washed through the sieve with 4 bar water pressure. 45 micron sieves (325 mesh) is used for this process. The sieve is then dried and sieves residue is weighed.

• Tamped density. : The tamped density is calculated from the initial weight of the sample and the resulting volume, reported in g/l. It is used for the purpose of calculating weight of product in powder form.

• DBP absorption : The DBP absorption is a numerical value used to indicate absorptive capacity of filler. Owing to the automatic measurement process, however, this method can be carried out more accurately than the determination of the oil absorption. The DBP absorption capacity is influenced by other parameters, such as the particle size.

Rubber Grade Precipitated Silica :
PPTS - 200 gives high dispensability, makes it better reinforcing silica and suitable for filling a natural, synthetic and latex rubber, transparent shoe
soles, tyres, tubes, rubber lining, vulcanization of rubber etc. to provide toughness and high resistance to abrasion.

Non Rubber Grade :

• Pesticide Grade : PPTS - 100 is most suitable for pesticides, insecticides & fungicides due to their extremely fine particles size and large surface area which account their use as an absorbent carrier and flow conditioner of solids and viscosity control of liquids. It has higher absorption, easier wetting, better compatibility with most toxicants and better chemical stability even after extended storage under tropical condition.

• Paint Grade : PPTS - 300 suitable for delustering or flattening effects in paints, prevents settling of pigment in storage, stabilizer emulsion and helps to covers greater surface area.

• Toothpaste Grade : PPTS - 400 suitable in the manufacturing of tooth powder & tooth paste. PPTS - 400 Silica when added to tooth powder or tooth paste acts as a good abrasive agent, thereby cleaning teeth thoroughly. The transparency of high porous and high surface area of Supersil-220 Silica permits the development of transparent tooth paste.

• Micronized Silica : PPTS - 500 is a superfine micronized Silica grade having all particles below 10 micron.