Experimental data and thermodynamic modeling of ternary aqueous biphasic systems of EO/PO polymers–Na2SO4–H2O

•Concentration of aqueous sodium sulfate solutions by extraction has been studied.•Experimental liquid–liquid equilibrium data were determined.•Purely empirical equilibrium relations and also the NRTL model were fitted to the data.•Good agreement between data and models was obtained.•Temperature dependent NRTL model parameters were found.

Liquid–liquid extraction using thermoresponsive polymers as solvents in aqueous two phase systems followed by induced phase separation to recover the polymers is a potential technology for water–salt separations. Here we report for seven polymers on their ternary systems containing water, sodium sulfate and the (block co)poly ether. Equilibrium data were measured at 298.15 K and 313.15 K and atmospheric pressure. Empirical equations have been used to correlate the experimental equilibria for both temperatures separately and the semi-empirical NRTL model has been applied with a temperature dependent parameter to describe the complete dataset for both temperatures together. Model predictions were in good agreement with the experimental data.