INTERACTIONS OF BINARY SOLVENTS WITH CHARGED EXPANDABLE CLAYS .1. THEORY

The interlayer space of fixed-charge, expandable, layered aluminosilic ate clays is considered filled with a two-component dielectric solutio n and treated as an open thermodynamic system. The composition of the interlayer solution, relative to the external solution, is obtained by performing a thermodynamic analysis that includes the work of polariz ation of the dielectric solution. The theory predicts that composition al changes are most dramatic when the component having greater polarit y is present to a smaller extent (less than or equal to 20 mol %). Fur thermore, the theory is shown to contribute significantly to the under standing of previously published adsorption isotherm data as well as s welling behavior of organo-clays in organic solvents.