Thermodynamics of adsorption from solution. Adsorption by activated carbon of the three binary systems involving n-butanol, n-heptane and n-dodecane

Abstract

Measurements of the adsorption by activated carbon of the three binary mixtures involving n-dodecane, n-heptane and n-butanol were made at 298 K. The data were tested for thermodynamic consistency by calculating the excess surface Gibbs energy of the interface between the pure liquids and the activated carbon surface. The adsorption data were also used to test the validity of the monolayer model of adsorption. This model is compatible with the data for (n-dodecane–n-heptane)/activated carbon, but a minimum thickness of two layers for (n-dodecane–n-butanol)/activated carbon and (n-heptane–n-butanol)/activated carbon is required to achieve thermodynamic consistency between the surface phase model and the experimental data. Surface activity coefficients were calculated for the last two systems and show that the adsorbed phases exhibit smaller deviations from ideality than the bulk phases.