ABSTRACT
A novel apparatus, PeDro, for high-pressure measurement of interfacial tension using the quasi- static procedure of pendant drop method is presented. Optimized experimental set-up allowed for accurate measurements in the two-component system of water and compressed carbon dioxide. Experimental error of measurement was smaller than 2%. Measurements were conducted in the range of (278 to 335) K and (0.1 to 20) MPa. The interfacial tension showed a pronounced dependence on pressure and temperature. Molecular dynamics (MD) simulations were performed for liquid–liquid and liquid–vapor interfaces between water and carbon dioxide at elevated pressures. Constant-volume production runs of 0.3 nanoseconds were used to estimate the water–CO2 interfacial tension at 323 K for a system comprising 512 SPC/E water molecules and 200 three-site CO2 molecules. Interfacial tension was obtained from the difference between pressure components normal and tangential to the interface. The results showed a good agreement with experimental data; our model system also reproduced the pressure-temperature relationship of the interfacial tension.
