3. Modification of Clay Minerals for Adsorption Purpose

The chemical nature and pore structure of clay materials generally influence their adsorption capability. In order to increase its adsorption capacity, modification of the pore structure of clay materials has been conducted chemically as well as physically. Inorganic acids, bases, salts, and surfactants have been used for modification of clay minerals. A combination of chemical and physical treatment process has also been employed to modify the surface and structure of clay minerals. The modification of clay minerals using acid can alter the crystalline structure of the clay minerals. The clay minerals modified with quaternary ammonium surfactant have a high affinity towards most of hydrophobic organic compounds. Even though the anionic surfactants are cheaper than other types of surfactants, the anionic surfactants are seldom used for clay modification compared to the cationic and nonionic surfactants. Nonionic surfactant organoclays were more chemically stable than cationic surfactant organoclays. This chapter also describes the use of Gemini surfactants as well as natural surfactant for modification of various clay minerals.