Clays are good adsorbents because of the existence of several types of active sites on the surface, which include Bronsted and Lewis acid sites and ion exchange sites. Clay minerals have different adsorption capacities for dyes. Adsorption capacities depend on the properties of the clay minerals and the adsorbate as well as experimental conditions. Clay minerals have many applications in industry due to their high surface area, porosity, thermal stability, specific active sites, and attractive adsorptive properties
The application of clays, especially bentonite, has attracted more and more attention because of their low-cost, easy availability, high cation exchange capacity and surface area. Because of their low cost, abundance in most continents of the world, high adsorption properties and potential for ion exchange, clay materials are strong candidates as adsorbents.