adsorption is the accumulation of atoms or molecules on the surface of a material. This process creates a film of the absorbate the molecules or atoms being accumulated on the adsorbent's surface. It is different from absorption, in which a substance diffuses into a liquid or solid to form a solution. The term sorption encompasses both processes.
Adsorption is often confused with absorption, where the substance being collected or removed actually penetrates into the other substance
Adsorption is a consequence of surface energy: in a bulk material, all the bonding requirements 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 a physical process in which weak secondary boundings with van der Waals forces plays role, or a chemisorption, in which covalent bonding is characteristic.
Adsorption is widely used in environmental technologies and soil remediation for soil air or soil gas treatment, for the treatment of the desorbed contaminants from solid soil by thermal desorption technology, for the recovery of valuable gases or vapours, for ground water, surface water, drainages water and leachate treatment, for the purification of extracts, etc.