Modeling the phase equilibria of a H2O-CO2 mixture with PC-SAFT and tPC-PSAFT equations of state

Water-carbon dioxide binary mixtures are important for a number of industrial and environmental applications. Accurate modeling of the thermodynamic properties is a challenging task due to the highly non-ideal intermolecular interactions. In this work, two models based on the Statistical Associating Fluid Theory (SAFT) are used to correlate reliable experimental vapor-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) data in the temperature range 298-533 K. CO2 is modeled as a non-associating or associating component within the Perturbed Chain-SAFT (PC-SAFT) and as a quadrupolar component within the truncated PC-Polar SAFT (tPC-PSAFT). It is shown that PC-SAFT with explicit account of H2O-CO2 cross-association and tPC-PSAFT with explicit account of CO2 quadrupolar interactions are the most accurate of the models examined. Saturated liquid mixture density data are accurately predicted by the two models.