Interfacial Tension and Liquid Viscosity of Binary Mixtures of n-Hexane, n-Decane, or 1-Hexanol with Carbon Dioxide by Molecular Dynamics Simulations and Surface Light Scattering

Abstract

In the present study, the interfacial tension and liquid viscosity of binary mixtures of n-hexane, n-decane, or 1-hexanol with carbon dioxide (CO2) were investigated by molecular dynamics (MD) simulations and surface light scattering (SLS). The latter technique was applied to study experimentally the influence of dissolved CO2 on the interfacial tension and liquid viscosity of binary mixtures of n-hexane with CO2 at 303.15 K and saturation pressures up to 5 MPa corresponding to a CO2 mole fraction in the liquid phase up to 0.75. For this system at vapor–liquid equilibrium, the liquid viscosity and interfacial tension were determined with average relative expanded uncertainties (k = 2) of (1.8 and 1.3) %. In equilibrium MD simulations for binary mixtures of n-hexane, n-decane, or 1-hexanol with CO2, the vapor–liquid equilibria including saturated densities as well as the interfacial tensions were predicted at temperatures of (303.15, 333.15, and 363.15) K for CO2 mole fractions in the liquid phase up to 0.52. For the binary mixtures of n-hexane with CO2, agreement between the measured and simulated data for viscosity and interfacial tension was found. With the three mixtures investigated by MD simulations, the influence of chain length and hydroxylation on the interfacial tension could be demonstrated. The simulations showed that the magnitude of CO2 enrichment at the vapor–liquid interface is more pronounced for solvents with larger surface tensions.