Granular Activated Carbon has a relatively larger particle size compared to powdered Activated Carbon and consequently, presents a smaller external surface. Diffusion of the adsorbate is thus an important factor. These carbons are therefore preferred for all absorption of gases and vapors as their rate of diffusion are faster. Granulated carbons are used for water treatment, deodorization and separation of components of flow system and is also used in rapid mix basins. GAC can be either in granular or extruded form.