Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Interfacial tension data and models are of great importance to the storage of CO2 in deep saline aquifers. In this study, the pendant-drop method combined with axisymmetric drop shape analysis was used in the interpretation of the interfacial behavior of CO2 and brine. Extensive experimental measurements of the interfacial tension between CO2 and an NaCl solution were acquired for pressures ranging from 3.0 to 12.0 MPa, temperatures from 300 to 353 K, and NaCl molalities from 0 to 1.8 mol*kg 1, for a total of 1,254 valid data points. All experiments were conducted in a pressure cell fitted with a capillary tube to create pendant droplets in a CO2-rich atmosphere. The experimental results indicated that interfacial tension decreased with increasing pressure and increased with temperature and salinity. As pressure increased to a certain point, the interfacial tension reached a plateau. At a given temperature, the CO2 aqueous system reached a plateau for different salinities under nearly the same pressure. However, the plateau pressure increased with temperature. The plateau interfacial tension value slightly increased with temperature and salinity. We also found a linear relationship between the change in interfacial tension and the molality concentration of brine. An empirical model was also proposed based on the Parachor model for the prediction of interfacial tension. Most results of this model deviated by less than +-5% from our experimental results, indicating that the model was a good fit to our experiments.