adsorption

Definition: Adsorption is the process by which filter media attracts unwanted molecules to its surface via a chemical charge. In adhesion the molecules of liquids, gases, and dissolved substances stick to the surface, as opposed to absorption in which the molecules actually enter the absorbing medium.

Some solids have the power to adsorb great quantities of gases. Charcoal, for example, which has a large surface area because of its porous nature, adsorbs large volumes of gases.