INVERSE GAS-CHROMATOGRAPHY STUDY OF MODIFIED SMECTITE SURFACES

Inverse gas chromatography at infinite dilution, employing alkanes and alkenes as probes, has been used to characterize the surface proper-ties of a series of smectites of varying chemical composition. The results of this study show that the acidic centers and the interlayer distances have a great influence on the specific interaction of the smectite surface with pi-bonds of alkenes. High values of the specific interaction parameter, epsilon(pi) are caused by the existence of strong acidic centers that are connected with interlayer cations as well as with the chemical structure of the mineral sheets. On the other hand, alkanes, whose interaction with the smectites is predominantly dispersive, are unaffected by changes in the clays' composition and/or structure.