DETERMINATION OF THE SURFACE-PROPERTIES OF ILLITES AND KAOLINITES BY INVERSE GAS-CHROMATOGRAPHY

The surface properties of illites and kaolinites of various origins an d formation conditions were measured by inverse gas chromatography (IG C) at infinite dilution conditions. The value of the dispersive compon ent of the surface energy (gamma(s)(d)) determined by IGC is significa ntly higher for these clays than the gamma(s)(d) of amorsphous silicas . This is explained by the partial insertion of a very small amount of injected alkane probes into structural defects located on the border layers of the clays. The use of branched bulky alkane probes allows th e evaluation of the clay's nanorugosity through the determination of a morphological index (I-M). The relation between gamma(s)(d) and surfa ce nanorugosity (I-M) confirms that the high values of gamma(s)(d) of the clays are representative only of these particular sites of adsorpt ion. (C) 1995 Academic press, Inc.