Adsorption of n-Alkanes by Wyoming Montmorillonite

Abstract

MUCH is known about the interlamellar adsorption of both inorganic and organic cations and polar organic molecules by clay minerals, but there is little information about the interlamellar adsorption of non-polar saturated hydrocarbons by expansible clays. Indeed, there seems to be little or no positive evidence for such adsorption. MacEwan¹ found no interlamellar adsorption of n-hexane or n-heptane by montmorillonite after boiling the mineral in the organic liquids, and he concluded that polar or polarizable groups are necessary to cause penetration and separation of montmorillonite sheets, and hence the formation of complexes. Similarly, Barshad² stated that the lack of expansion in montmorillonite on treatment with saturated aliphatic hydrocarbons was attributable to their non-polar nature. It was thus to be expected that adsorption of non-polar molecules like n-hexane would occur only on external surfaces as a result of “dispersion” or London-Van der Waals forces.