Measurements and modelling of interfacial tension for water + carbon dioxide systems at elevated pressures

A novel apparatus, PeDro, was used to measure interfacial tension in a two-component system made of water and compressed carbon dioxide at temperatures ranging 278–335 K and pressures 0.1–20 MPa. Our optimized experimental setup utilized the quasi-static pendant drop method and ensured experimental errors below 2%. The interfacial tension showed a pronounced dependence on pressure and temperature. A regression function was derived that allows to interpolate between the experimental data with high precision. Molecular dynamics simulations were performed for liquid–liquid and liquid–vapor interfaces between water and carbon dioxide at elevated pressures. The interfacial tension was obtained from long constant-volume production runs as the difference between normal and tangential pressure components. The results showed a good agreement with experimental data, with our model system reproducing faithfully the pressure–temperature dependence of the interfacial tension.