Vapor-liquid interfacial properties of binary mixtures from molecular simulation and density gradient theory

Properties of the vapor-liquid interface of 16 binary mixtures were studied using molecular dynamics simulations and density gradient theory in combination with the PCP-SAFT equation of state. All binary combinations of the heavy-boiling components (cyclohexane, toluene, acetone, and carbon tetrachloride) with the light-boiling components (methane, carbon dioxide, hydrogen chloride, and nitrogen) were investigated at 0.7 times the critical temperature of the heavy-boiling component in the whole composition range. Data on the surface tension, the enrichment, the relative adsorption, and the interfacial thickness, as well as for the vapor-liquid equilibrium and Henry’s law constant are reported. The binary interaction parameters were fitted to experimental data in a consistent way for all systems and both methods. Overall, the results from both methods agree well for all investigated properties. The interfacial properties of the different studied systems differ strongly. We show that these differences are directly related to the underlying phase equilibrium behavior.