SELECTIVE LIQUID SORPTION AND WETTING OF PILLARED MONTMORILLONITES

Pillared montmorillonite was used as an adsorbent for binary mixtures of hydrocarbons and alcohols (benzene/n-heptane; ethanol/cyclohexane; ethanol/toluene; propanol/toluene). The adsorbent was prepared from th e Na-form of a bentonite from Milos by reaction with polyhydroxoalumin ium solutions. The adsorption behaviour of the pillared montmorillonit e was characterized by the adsorption excess isotherms and the heats o f immersion. Sorption capacities and wetting properties differed signi ficantly from those of the Na-montmorillonite. Benzene was adsorbed pr eferentially from mixtures with n-heptane. Ethanol and propanol were a lso preferentially adsorbed from mixtures with cyclohexane and toluene but the curves showed azeotropic points at molar fractions of alcohol s of 0.7-0.9. The calorimetric data revealed the partially hydrophobic character of the pillared montmorillonite. The heat of wetting of ben zene or toluene on the pillared samples was distinctly higher than tha t of ethanol whereas ethanol gave the highest wetting enthalpies on Na -montmorillonite.