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What's silica?

Chemical formula: SiO2 Silica is also called as "silicon dioxide" or "unhydrous silicic acid". It is 60% component of earth crust.
It is colorless solid at ambient temperature. As familiar examples, there is quartz sand, crystal and so on. SiO2 has some crystal structures like quartz, tridymite, cristobalite.
On the other hand, our silica is artificial amorphous porous silica made from sodium silicate. Amorphous type silica, it is dificult to remain your body. So the safety level is high.

What is porous silica?

At first, nano size primary particle is made by polymerization of SiO2. Then, the primary particles are agglutinated and the particle become secondary particle. The gap between primary particles is void volume of porous silica.
By the control of prymary particle size and agglutination, we change the particle size, pore volume, specific surface area and so on.

What's silanole

Silanole group: Si-OH
There are a lot of silanol group on the surface of primary particle which made by polymerization. The silanol groups indicate weak acidity.
Silanol has chemistry with substance which has hydroxyl groups (water, alchole) and basic substance (ammonia, amin).
Our company, the number of silanol group is checked by ignition loss test.
Examples)
 SUNSPHERE
  H-31 6400 μmol/g
  L-31 4400 μmol/g
Silanol group has hydrophilicity.

Stability of Silica gel

Silica gel is stable for heat and acid chemicals except hydrofluoric acid (HF). On the other hand, it has solubility for alkaline and HF.
Dissolution mechanism by HF SiO2 + HF(aq) → H2SiF6 + H2O
Dissolution mechanism by NaOH SiO2 + 4NaOH → Si(ONa)4 + 2H2O
Minor component analysis for silica, once the silica is solved by HF. And then, the minor componemt is checked by ICP.
Etching of glass technology is application of this principle.

Oil absorption

There is oil absorption test in the SUNSPHERE evaluation tests.
This result shows the porous silica has how large pore volume. It is also shows the support capacity of the porous silica.
This method is set by JIS K 5101-13-1 as standard test of absorption capacity for pigment and body pigment. JIS means Japanese Industrial Standards.