Clay Soil Modification Techniques for the Adsorption of Heavy Metals in Aqueous Medium: A Review

Variety of clays and clay minerals play an important role in the environment and used as an effective adsorbent material for the removal of toxic metal ions from water solution (Crini, 2010). The use of clays as adsorbent have advantages upon many other commercially available adsorbents in terms of low-cost, an abundant availability, high specific surface area, excellent adsorption properties, nontoxic nature, and large potential for ion exchange (Crini and Badot, 2010; Gupta et al., 2013; Rao et al., 2014; Rao et al., 2015). Clays also contain exchangeable cations and anions held to the surface (Miranda-Trevino and Coles, 2003; Crini and Badot, 2010). For these reasons, the attention of scientists worldwide has been focused on using natural or modified clay materials as adsorbent for water treatment.