“…The theory of surface and interfacial thermodynamic interactions was recently reviewed by van Oss et al (1988) and only those aspects which are essential to the present discussion will be mentioned here. The surface thermodynamic properties have been deter-mined for a number of phyllosilicate minerals: hectorite (van Oss et al, 1990), talc and pyrophyllite , Ca-montmorillonite (Chassin et al, 1986), a group of natural smectite minerals (Giese et al, 1989), illite (Li et aL, 1991) and kaolinite (Chibowski and Staszczuk, 1988;Murphy et aL, 1991). In addition, the role of interfacial interactions, and especially the importance of the Lewis acid/base contribution to the flocculation of hectorite has been examined (van Oss et al, 1990); the thermodynamics of adsorption of human serum albumin on several clay minerals has been studied (Costanzo et al, 1991b); and the changes in surface properties of humic-clay complexes have been reported (Jouany, 1991).…”