Prediction of surface tension for pure non-polar fluids based on density functional theory

Abstract

A method for the prediction of surface tension of non-polar fluids has been developed based on the density functional theory. The Barker–Henderson perturbation theory and statistical associating fluid theory are used to establish an equation of state (EOS). The parameters m, σ and ε/ k of the EOS are correlated by simultaneously fitting the saturated vapor pressure and the liquid density data. The surface region of a pure liquid is divided into many extreme thin layers. The chemical potentials of different layers in the surface region are equal and lead to a constant by optimizing the surface thickness. The density profile is obtained from the optimized surface thickness and a hyperbolic tangent function. By use of the regressed parameters in the EOS, the surface tensions for 18 pure non-polar fluids are predicted and the results are satisfactory.