Equilibrated Interfacial Tension Data of the CO₂–Water System at High Pressures and Moderate Temperatures

This work presents interfacial tension (IFT) data for the CO 2 –water system in the pressure and temperature range of (1.48 to 20.76) MPa and (298.15 to 333.15) K. The IFT evaluation is carried out using the pendant drop method. Inaccuracies observed in the literature such as consideration of pure phase densities and short presaturation time durations have been avoided by utilizing saturated phase densities and long presaturation time durations. The water-rich phase density is evaluated using a literature correlation, and the CO 2 -rich phase density is evaluated using equation-of-state modeling approach. Also, presaturation times were extended up to 24 h to obtain equilibrated IFT data for the CO 2 –water system. It is observed that the IFT reduces with pressure when the CO 2 -rich phase is a gas at both subcritical and supercritical temperatures. Further, the IFT values reached a plateau at about 23 mN·m –1 at higher pressures (13.89 to 20.79 MPa) and for the entire temperature range. A predominant buoyancy effect is observable at higher pressures due to the reduction in phase density differences. Comparatively, the evaluated IFT data trends are about (5 to 7) mN·m –1 lower at high pressures than those reported in most of the literature.