ABSTRACT
Clay minerals are of interest for a number of reasons: they have high surface areas, their surfaces are reactive, and many clay minerals occur in deposits that are readily accessible, producing a product at moderate cost. There is a growing use of these materials for a range of applications, such as geotechnical barriers, adsorbents for toxic organic chemicals (Mortland et al., 1986; Boyd et al., 1988) and heavy metals, substrates for the delivery of antimicrobial materials (Oya et al., 1991, 1992; Ohashi and Oya, 1992), removal of bacteria (Cookson, 1970) and biopolymers (van Oss et al., 1995a,b), and thickeners for both aqueous and nonaqueous systems (Neumann and Sansom, 1971; Alderman et al., 1989; Kemnetz et al., 1989). All of these applications involve an interaction that takes place at an interface and thus can be described in terms of surface thermodynamic quantities.
