Methods involving gas and liquid sorption and immersion microcalorimetry were used to study the surface properties of the clay mineral palygorskite and its derivatives in which the surface had been modified to various extents with the hexadecylpyridinium (HDP) cation. The sorption studies revealed that surface modification with this cationic surfactant blocks the micropores in the palygorskite silicate chains, whereupon the adsorption capacity decreases. An additional factor influencing the selective sorption of mixtures of benzene with various alcohols is the change in the polarity of the surface. The enthalpies of immersion showed that the solid-liquid interface interaction is altered by the adsorption of the HDP cation, i.e., by the decrease in polarity of the surface. An almost linear correlation was found between the molar enthalpies of immersion and a factor describing the polarity of the surface. Both the differences in adsorption of the various alcohols and the changes in the liquid sorption properties due to the surface modification were characterized with surface thermodynamic potential functions.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry