Bentonite is a clay consisting of smectite minerals, mainly montmorillonite (MMT). Montmorillonite is a member of the smectite family with a general composition of (Na,Ca)0.33 (Al,Mg)2 (Si4O10)(OH)2nH2O, where the levels of sodium, calcium, aluminum, magnesium, and water vary with location, both within and between layers. Sodium and calcium are interchangeable ions giving MMT a high ion exchange capacity. MMT has an aluminum-silicate layered structure with a net negative charge generated by isomorphic substitutions. The intrinsic negative charge is compensated with inorganic cations (typically Na+ or Ca2+ ions). The high cationic exchange capacity, high specific surface area and intrinsic negative charge make MMT a favourable adsorbent for cationic synthetic and natural molecules. Interlayer of nano sized montmorillonite is suitable for uploading drug molecules.
