The surface tension of liquid mixtures is an important transport property that reveals information on the structure and energetics of the surface region between two phases and exerts a considerable influence on the transfer of mass and energy across interfaces. An estimate of this surface property is required in many fields including separation processes and environmental engineering. As part of the important work on the surface tension of liquids, it has included the theoretical determination and correlation by different models. Several different approaches have been used to predict the surface tension of mixtures which include the gradient theory [1], the parachor [2], and also activity coefficient models [3–5]. This work presents a thermodynamic model and a calculation method to estimate and predict mixture surface tension values, as a function of concentration. In addition surface activity and surface mole fraction of more than 100 organic binary mixtures have been predicted based on classical thermodynamic model and compared with experimental data [6]. Various binary systems show different deviation values from experimental data. For mole fraction of the organic component more than 0.20, the surface tension is extremely sensitive to changes in composition and show more deviation from experimental data. In this study systems formed by components of the same chemical nature, and molecular size, tend to show a more“ideal” behavior.
