Abstract

We report surface tension measurements coexisting densities, concentration profiles along the interfacial region, surface activities, and relative Gibbs adsorption isotherms for binary mixtures of carbon dioxide (CO2) + n-decane . (n-C10H22) at 344.15 K and carbon dioxide (CO2) + n-eicosane (n-C20H42) at 323.15 K over a pressure range from 0.1 Mpa to 10.35 MPa. The results are obtained by employing a broad approach that integrated experiments with both theory and molecular simulations to gain an enhanced multiscale description of the interfacial region. Measurements are based on the use of a high-pressure pendant drop tensiometer coupled to a high-pressure densimeter. Theoretical modeling is carried out using the Square Gradient Theory based on a version of the statistical associated fluid theory (SAFT) equation of state at the molecular level, Molecular dynamics and the simulations uniquely share the same underlying simulations. Reassuringly theory experiments and moleculare simulations agree with each other in the description of the bulk phase equilibria and interfacial tension. It is observed that for both mixtures the interfacial decreased as the pressure increase. Furthermore there is quantitative agreement between the theoretical predictions and the results obtained from the molecular simulations of surface activities profiles along the interfacial region and relative adsorption isoitherms at interfaces. A remarkable high excess CO2 larger in eicosane than in decane is detected along the interface