Lajos György Nagy

Sorption and immersional wetting on clay minerals having modified surface: II. Interlamellar sorption and wetting on organic montmorillonites

Abstract Adsorption of methanol-benzene mixtures and heats of immersion have been investigated on the organic derivatives of montmorillonite. The surface of the mineral was modified by n-alkyl pyridinium and dimethyldihexadecyl ammonium ions. In the case of completely exchanged samples the adsorption capacity volumes agree with the interlamellar volumes calculated from X-ray diffraction data rather well. The organophilicity is characterized by the proportion of the nonpolar/polar surfaces. The specific enthalpies of immersion have been measured in methanol, benzene, and their mixtures. The immersion shows endothermic-exothermic or endothermic heat effects.

Sorption and immersional wetting on clay minerals having modified surface. I. Surface properties of nonswelling clay mineral organocomplexes

Abstract Adsorption of methanol-benzene mixtures and the immersional wetting properties have been investigated on nonswelling clay minerals with lamellar structure (kaolinite and illite) and on their organocomplexes obtained by hexadecyl-pyridinium cations (HDP+). It has been found that the surface modification can influence the selective liquid adsorption. To interpret unambiguously the extent of the surface modification the nonpolar-polar surface area ratio can be calculated from the sorption data. From the excess isotherms and the enthalpy of immersion the surface thermodynamic potential functions have been calculated. The changes of these functions and the equilibrium constant of the adsorption with the surface polarity is given. Adsorption capacity data and immersional wetting experiments indicate that the surface extension of these organocomplexes can change in some degree.

Adsorption of liquid mixtures on bentonite and organophilic bentonite

Selective sorption of binary mixtures has been studied on bentonite and organophilic bentonite. Adsorption excess isotherms on these adsorbents have been determined for benzenen-n-heptane and alcohol-benzene mixtures, and the adsorption capacity of the components has been calculated by the analysis of the excess isotherms. The organocomplex swells only to a small extent in benzene-n-heptane mixtures, while in alcohol-benzene mixtures significant swelling and disaggregation occurs owing to positive adsorption of the alcohols. The results of adsorption measurements are concordant with the swelling and disaggregation characterized by sediment volume measurements.

Sorption and immersional wetting properties of palygorskite and its hexadecylpyridinium derivatives

Abstract 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.

Liquid sorption and immersional wetting on dealuminated Y-type zeolites

Abstract The adsorption and immersional wetting properties of Na-Y zeolite essentially change by dealumination of the zeolite. By studying the adsorption of alcohol-benzene and benzene- n -heptane mixtures it was found that the dealumination results in a decrease of the adsorption capacity of about 25% and in a depolarization of the surface. The decrease of the surface energy is also supported by microcalorimetric immersion measurements. The changes of excess free energy, excess enthalpy, and excess entropy accompanying the wetting process were calculated from the experimentally determined adsorption excess isotherms and immersion wetting data. The thermodynamic potential functions indicate that dealumination results in a considerable decrease of the sorption selectivity and of the surface energy of zeolite Y.