DSORPTION ISOTHERM
The adsorption of a gas or vapours on a solid surface in a closed vessel is a reversible process and depends on pressure and temperature. The relationship between the amount of substance adsorbed per unit mass of the adsorbent and the equilibrium pressure (in case of a gas) or concentration (in case of solution) at constant temperature is known as the adsorption isotherm. Five different types of adsorption isotherms have been observed in the adsorption of gases on solids. These are shown in Fig.3.2.