ABSTRACT
Clay minerals are abundant in nature and have many industrial uses, such as in the ceramics, cement, paper, cosmetics, print, and drug industries. Clays are also extensively used in environmental remediation due to unique properties, such as high surface area, strong chemical stability, non-toxic nature, and the adsorptive and ion exchange properties (Churchman et al., 2006). Clays are generally produced by mining but can be increased in value by surface modification. Naturally occurring clay minerals are intrinsically hydrophilic in nature. As a result, clays have a good affinity for ionic contaminants, such as heavy metal cations, but do not significantly interact with hydrophobic organic contaminants. Clay minerals’ surface modification with organic compounds, such as quaternary ammonium compounds (QACs) can produce modified clays with a high affinity for organic contaminants. Modified clay minerals thus prepared are known as organoclays (Boyd et al., 1988; Jordan and Williams, 1954; Sarkar et al., 2012c; Xi et al., 2005b). Depending on the type of organic compounds used for modification, organoclays can act as the adsorption sink for both hydrophobic organic contaminants and ionic metals and metalloids (Sarkar et al., 2012a, b, c).
