Solubility of carbon dioxide in pentaerythritol ester oils. New data and modeling using the PC-SAFT model

In this work, the solubility of carbon dioxide, CO₂, in pentaerythritol tetraheptanoate (PEC7) and in pentaerythritol tetranonanoate (PEC9) has been performed from 283 to 348 K and pressures up to 7.5 MPa in an isochoric high-pressure gas solubility apparatus. The solubility values are very similar in terms of mole fractions of CO₂ in both pentaerythritol esters. The experimental gas solubility data, together with those available in the literature for other CO₂ + pentaerythritol tetraester systems, were satisfactorily correlated with the PC-SAFT equation of state. The average absolute deviations of the gas solubility correlations were less than 3.9% for all the systems. In addition, PC-SAFT model was applied in a semi-predictive manner: the pure component's molecular parameters and the binary interaction parameter optimized from solubility data were used to calculate the types of the phase diagram as well as the densities and excess molar volumes in broad temperature and pressure ranges. The results obtained show the robustness of the model and these parameters to calculate properties not included in the fitting procedure.