The term "adsorb" refers to the process by which a substance, typically a gas or a liquid, adheres to the surface of a solid or a liquid without forming a chemical bond with it. In other words, adsorption involves the accumulation of molecules or particles on the surface of a material, rather than their incorporation into its structure.
Adsorption occurs due to the attractive forces between the adsorbate (the substance being adsorbed) and the adsorbent (the material onto which the adsorbate adheres), which can be van der Waals forces, electrostatic interactions, or other types of interactions. The degree of adsorption depends on factors such as the surface area and porosity of the adsorbent, the nature of the adsorbate, and the temperature and pressure of the system. Adsorption is widely used in various fields, such as in the purification of water and air, in gas separation processes, and in catalysis.