Zeolite is a family of several microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula Mn+1/n(AlO2)−(SiO2)x・yH2O where Mn+1/n is either a metal ion or H+. These positive ions can be exchanged for others in a contacting electrolyte solution. H+ exchanged zeolites are particularly useful as solid acid catalysts.
Zeolite exhibited in the Estonian Museum of Natural History
A form of thomsonite (one of the rarest zeolites) from India
Polished thomsonite
Natrolite from Poland
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which a fluid is dissolved by or permeates a liquid or solid. While adsorption does often precede absorption, which involves the transfer of the absorbate into the volume of the absorbent material, alternatively, adsorption is distinctly a surface phenomenon, wherein the adsorbate does not penetrate through the material surface and into the bulk of the adsorbent. The term sorption encompasses both adsorption and absorption, and desorption is the reverse of sorption.
Activated carbon is used as an adsorbent
Activated carbon nitrogen isotherm showing a marked microporous type I behavior
Silica gel adsorber for NO2, Fixed Nitrogen Research Laboratory, ca.1930s