A chemical and thermodynamic model of aluminous dioctahedral 2:1 layer clay minerals in diagenetic processes: regular solution representation of interlayer dehydration in smectite

Abstract

Equilibrium constants (K) and regular solution Margules parameters (Ws) for the dehydration of Na- and Ca-smectite at 25°C and 1 bar were generated. These values, together with the electrostatic properties of the interlayer cations were used to estimate values of log K and Ws for the dehydration of K-, NH4-, Rb-, Cs-, Mg-, Sr-, and Ba-smectite. Equilibrium hydration states at 25°C and 1 bar predicted from the estimated values of log K and Ws are in close agreement with those reported in the literature. This observation strongly supports the general validity of describing smectite dehydration in terms of regular solution theory. -from Authors