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

ABSTRACT

We present new experimental data on the isobaric vapor-liquid equilibria (VLE) of four binary mixtures of water with ethylene glycol, diethylene glycol, triethylene glycol or tetraethylene glycol, measured at three different system pressures (0.05, 0.07 and 0.1 MPa). Water activity coefficients were estimated from the mixtures boiling temperatures and used to rationalize the effect of the increasing glycols chain length on the molecular interactions with water. The soft-SAFT equation of state was used to describe the experimental VLE data of these highly non-ideal systems, providing insights into the molecular interactions leading the macroscopic behavior of the mixtures. Glycols and water were both modeled as associating molecules, with models and parameters from previous works, in a transferable manner. Soft-SAFT accurately reproduces the experimental data using one single, state independent, binary interaction parameter to correct the mixtures dispersive energy. It is further shown that the parameterization obtained from the pure glycols can be used to provide accurate predictions of the water activities in aqueous solutions of PEGs of higher molecular weight (600-6000 g/mol) highlighting the soft-SAFT robustness and the soundness of the parameterization used.