Interfacial Tensions of Industrial Fluids from a Molecular-Based Square Gradient Theory

This work reports a procedure for predicting the interfacial tension (IFT) of pure fluids. It is based on scaling arguments applied to the influence parameter of the van der Waals theory of inhomogeneous fluids. The molecular model stems from the application of the square gradient theory to the SAFT-VR Mie equation of state. The theory is validated against computer simulation results for homonuclear pearl-necklace linear chains made up to six Mie (lambda-6) beads with repulsive exponents spanning from lambda=8 to 44 by combining the theory with a corresponding states correlation to determine the intermolecular potential parameters. We provide a predictive tool to determine IFTs for a wide range of molecules including hydrocarbons, fluorocarbons, polar molecules, among others. The proposed methodology is tested against comparable existing correlations in the literature, proving to be vastly superior, exhibiting an average absolute deviation of 2.2%. (C) 2016 American Institute of Chemical Engineers