Adsorption of n-Aliphatic Alcohols from Dilute Aqueous Solutions on RNH3-Montmorillonites. III. Interlamellar Aggregation of the Adsorbate

Michael S. Stul and Jozef de Bock
Laboratorium voor Oppervlaktescheikunde, Katholieke Universiteit Leuven Kardinaal Mercierlaan 92, B-3030 Leuven (Heverlee), Belgium

Abstract: The large amount of water in the interlamellar space of alkylammonium montmorillonites in aqueous solutions is not fixed by intercalated hexanol or octanol. The hydration of the NH3+-group and the filling of the empty spaces between the carbon chains are responsible for this phenomenon. Hydrogen bonds between the alcohols and the ammonium groups reduce the enthalpy of solution of hexanol and octanol in the interlamellar region at infinite dilution to +17.6 and +12.7 kJ/mole, respectively. Self-association of the alcohols further diminishes the enthalpy of solution at higher alcohol concentration. The interlamellar fixation of the RNH3 cations prevents a micellization as has been obtained in bulk solutions. At a given alcohol concentration smectic type aggregates, i.e., double layers of alcohol molecules, appear as shown by an increase of the basal spacing of the organo-clay complexes. The aggregate formation is favored by a longer chain length of both the cation and the alcohol.

Key Words: Adsorption • Alcohol • Alkylammonium cations • Intercalation • Micellization • Montmorillonire

Clays and Clay Minerals; August 1985 v. 33; no. 4; p. 350-356; DOI: 10.1346/CCMN.1985.0330412
© 1985, The Clay Minerals Society
Clay Minerals Society (www.clays.org)