Adsorption of n-alkanols at alkane/water interfaces

Abstract

The adsorption of a series of long-chain n-alkanols from various alkanes to alkane/water interfaces has been studied. Some general features of the graphs of surface pressure against solute concentration are presented and, where possible, comparisons are made wih previous work. Standard free energies of adsorption of the alkanols have been determined; they vary by a small but significant amount with both alkanol and alkane chain length. The interfacial concentrations of the alkanols have been determined by the use of the Gibbs adsorption equation. The usefulness of surface equations of state, based both on a two-dimensional gas model and a two-dimensional solution model for the interface, has been investigated. The latter model is probably the more physically realistic but the present results have not proved this to be so. It is concluded that the measurements of limiting adsorptions would be useful in this connection.