Adsorption of n-alkane vapours on graphon

Abstract

Adsorption isotherms on Graphon have been obtained for a series of n-alkanes from C₅ to C₁₂. Isosteric heats of adsorption as a function of fractional surface coverage were calculated for the members C₆, C₇ and C₈. Areas per molecule at monolayer coverage indicate that molecules adsorbed in the first layer lie flat on the Graphon surface. The increment per methylene group is in good agreement with a lattice fit theory with hydrogen atoms on one side of the zig-zag carbon chain located in the centres of hexagons of the graphitic basal planes.

Heats of adsorption for n-alkanes C₇ and above show considerable enhancement just below monolayer coverage. Such enhancements would result from a lattice fit configuration allowing increased adsorbate-adsorbent interaction.