Thermodynamic studies on adsorption at interfaces. VI. Interface between cyclohexane-benzene mixture and water

The thermodynamic method developed in this series has been extended to be applicable to the interface between two fluid mixtures. The interfacial tension of cyclohexane-benzene mixture against water has been measured as a function of temperature, pressure, and composition. By applying the equations derived, the excess numbers of moles of cyclohexane and benzene per unit area and the thermodynamic quantities of interface formation have been evaluated numerically. It has been concluded that the affinity of the π-electron of benzene for water causes the density of benzene in the interfacial region to be considerably larger than that in the bulk phase. This conclusion has been confirmed by estimating the mole fraction of benzene at the interface defined on the basis of the assumption that the interfacial region is monomolecular.