Study on surface tension for non-polar and associating fluids based on density functional theory

A method for the prediction of surface tension of non-polar and associating fluids has been developed based on the density functional theory (DFT). The WCA perturbation theory and the SAFT are used to establish the equation of state (EOS). The adjustable parameters are correlated by simultaneously fitting the saturated vapor pressure and the liquid density data with the EOS. The local density approximation (LDA) is applied to the reference term and the mean field approximation (MFA) is used for perturbation term. The density profile is obtained by minimizing the grand potential functional. The surface thickness is calculated by "10%-to-90%-width" method. By use of the regressed parameters in EOS and the obtained density profile, the surface tensions for 13 non-polar fluids and 10 associating fluids are predicted satisfactorily.