Modeling the phase equilibria of a H₂O–CO₂mixture with PC-SAFT and tPC-PSAFT equations of state

Abstract

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.