A study of the adsorption thermodynamics of n-hexane on ion-exchanged X zeolites

Abstract

In this work, the free eneregy changes and entropy changes of adsorption of n-hexane on zeolites of the MxNa87-2XX (M = Co, Ni, Zn, Cd) type were determined using their isosteric sorption heats. It was found that the exchange of Na+ ions in NaX with bivalent cations (Co, Ni, Zn, Cd) significantly alters the adsorption characteristics of NaX zeolite. The free energy changes and entropy changes of n-hexane adsorption were dependent on the surface coverage and on the nature of the charge-balancing cation. The specific influence of the exchanged cations on the free energy changes and entropy changes of sorption of n-hexane originates from the size, location and electronic configuration of the cation.