A thermodynamic model for calculating the surface tension of pure liquids and liquid mixtures

Kirkwood and Buff theory is used to develop a surface tension equation for pure liquids and liquid mixtures by treating the real liquid as a Lennard-Jones fluid. The calculated results for 54 pure liquids over a wide range of temperatures show that this equation is accurate and easy to use. The total relative deviation is less than 1. 1%. The equation developed for pure liquids was extended to mixtures using vdW-1 mixing rule. The deviations of predicted and correlated surface tension data for 21 binary systems were within 7.0% and 2.0%, respectively. With the adjustable parameters obtained from binary systems, the equation can accurately predict the surface tension of multicomponent systems.