A classical thermodynamic model for the first time is used to derive an equation for the standard Gibbs energy of adsorption and surface properties for ionic liquids binary mixtures. Where experimental surface tension of the mixtures is available, the agreement between the calculated and the experimental data is found to be very good. Bulk mole fraction and surface tension of one of the pure component are necessary inputs for this equation. In addition, to find more information about surface structure of binary mixtures, the surface tension of binary mixtures has been studied using extended Langmuir model (EL)
