Adsorption is the
adhesion of
atoms,
ions or
molecules from a gas, liquid or dissolved solid to a
surface.
[1] This process creates a film of the
adsorbate on the surface of the
adsorbent. This process differs from
absorption, in which a
fluid (the
absorbate) is
dissolved by or
permeates a liquid or solid (the
absorbent), respectively.
[2] Adsorption is a
surface phenomenon, while absorption involves the whole volume of the material, although adsorption does often precede absorption.
[3] The term
sorption encompasses both processes, while
desorption is the reverse of it.
Similar to
surface tension, adsorption is a consequence of
surface energy. In a bulk material, all the bonding requirements (be they
ionic,
covalent or
metallic) of the constituent
atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as
physisorption (characteristic of weak
van der Waals forces) or
chemisorption (characteristic of covalent bonding). It may also occur due to electrostatic attraction.
[5]
https://en.wikipedia.org/wiki/Adsorption#:~:text=Adsorption is the adhesion of,the surface of the adsorbent.
Rooh Afza
https://en.wikipedia.org/wiki/Rooh_Afza