Use of the Gibbs equation to calculate adsorption into monolayer-covered surfaces

Abstract

A formal equation has been derived to describe the change in equilibrium surface pressure when the concentration of a soluble surfactant is varied in a subphase covered by a constant amount of insoluble monolayer on a fixed area of surface. Approximations are suggested which enable the equation to be applied to experimental data for the calculation of the surface excess concentration of surfactant.

An example is given and the surface penetration results discussed.