Ethylene Glycol Sorption by Homoionic Montmorillonites

Summary Experimental procedures giving complete unimolecular surface coverage of montmorillonite by ethylene glycol (EG) are described. The EG sorption data, excluding rate effects, are independent of the nature of the exchangeable cations associated with the clay surfaces. The amount of EG sorbed (0.357±0.007 g EG/g montmorillonite) is larger than that obtained following previously recommended techniques based on low pressure equilibration with CaCl 2 ‐EG mixtures (solvates) of relatively small EG content or on dynamic approaches. In both of the latter, the extent of EG sorption is determined by the exchangeable cation‐EG interaction and not by the real extent of the surface. Na‐ and K‐saturated montmorillonite‐EG complexes are less stable than those formed from Ca or Mg clay.