I want to purchase colloid silica as mentioned in your research paper. However, the supplier refer it as silica gel. So, I am a bit confused and would like you to clarify this issue regarding the colloid silica used, e.g. particle size, concentration.
Article Silica-alginate-fungi biocomposites for remediation of polluted water
Hi Kevin,
Silica gel and colloidal silica are two different things.
Colloidal silica is prepared by dispersing very fine silica particles in a solvent by the help of some surfectant and defloculant. Surfectant and defloculat are used to ensure the mechanical stability of the system (against precipitation) and to prevent the agglomeration of the particles. Silica particles are almost always amorphous in nature and the surface of the particle is hydrated as [Si(OH)n]^(4-n)+ (simply called hydrated silica), n depends on the pH of the colloidal system.
On the other hand the silica gel is produced by acid digestion of sodium silicate followed by gel precipitation. Afterwards, the gel is clenead and dried to produce a highly porous structure with high surfeace area. This makes the materials highly absorbent specifically for moisture. The gel is tranparent colourless in nature. However, in most of the labs pristine silica gel comes with a blue color which after water absorption turns into light pink. This color change is associated with added cobalt chloride (CoCl2). Dry blue color is manifested by bivaant Co2+ ion which after moisture absorption converts into bivalent hexaqua ion [Co(H2O)6]2+. This ion gives pink color.
I have enjoyed this discussion and hope so would you. Cheeers man....
Silica gel, as you noted, comes in a wide range of particle sizes. Colloidal to me refers to small particle sizes that are small enough for the particles to remain in suspension.
http://en.wikipedia.org/wiki/Colloidal_silica
colloidal silica can be found for example (LUDOX® HS-30 colloidal silica )
http://www.sigmaaldrich.com/catalog/product/aldrich/420824?lang=en®ion=US
Hi Kevin,
Silica gel and colloidal silica are two different things.
Colloidal silica is prepared by dispersing very fine silica particles in a solvent by the help of some surfectant and defloculant. Surfectant and defloculat are used to ensure the mechanical stability of the system (against precipitation) and to prevent the agglomeration of the particles. Silica particles are almost always amorphous in nature and the surface of the particle is hydrated as [Si(OH)n]^(4-n)+ (simply called hydrated silica), n depends on the pH of the colloidal system.
On the other hand the silica gel is produced by acid digestion of sodium silicate followed by gel precipitation. Afterwards, the gel is clenead and dried to produce a highly porous structure with high surfeace area. This makes the materials highly absorbent specifically for moisture. The gel is tranparent colourless in nature. However, in most of the labs pristine silica gel comes with a blue color which after water absorption turns into light pink. This color change is associated with added cobalt chloride (CoCl2). Dry blue color is manifested by bivaant Co2+ ion which after moisture absorption converts into bivalent hexaqua ion [Co(H2O)6]2+. This ion gives pink color.
I have enjoyed this discussion and hope so would you. Cheeers man....
Colloidal silica is what people call silica nanoparticles, that is less or about 100 nm. It does not precipitate. You may centrifuge colloidal silica above 15.000 rpm but the light particles will remain in suspension. You cannot buy it, just prepare it.
Silica gel are chuncks of SiO2 obtained from Na2SiO3 neutralized with HCl, particle size range from 10 to 100 microns.
Colloidal silica is sold under the brand name Aerosil.It is manufactured by Degussa A G,GERMANY.
Colloidal silica is a liquid colloid form of silica and Gel is crystalline solid material, so both are different.
They are not the same ,although you can make a colloidal silica if you use very fine silica particles which can suspend in a solution.
No, colloidal silica is not silica gel.
See both of the following for good descriptions:
https://en.wikipedia.org/wiki/Colloidal_silica
https://en.wikipedia.org/wiki/Silica_gel
Grace&Co offers LUDOX, a range of colloidal sillica products.
Does anyone have experience with these?
In Pharmaceutical preparations we use colloidal silica (Aerosil) regularly. In making oral suspension it is used as a suspending agent.It is also used as a lubricant in making compressed tablet.
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