Liquid–liquid phase equilibria for ternary systems of several polyethers with NaCl and H2O

• Aqueous two-phase systems containing (block co-)polyethers were applied for concentration of aqueous salt solutions.
• Dehypon blockcopolymers consisting of ethylene oxide, propylene oxide and a C12–14 fatty alcoholate groups selectively took up significant amounts of water and concentrated the salt in the raffinate phase.
• The systems were modeled with the NRTL model.
• Good agreement between data and model was observed.

Liquid–liquid extraction using polymers followed by induced phase separation is a potential energy reducing technology for water–salt separation. Ternary equilibrium data have been determined and reported for the (block co)poly ethers–sodium chloride–water systems at two different temperatures at 298.15 K and 313.15 K and atmospheric pressure. The experimental data were correlated with the NRTL model, and the obtained binary interaction parameters to describe the ternary liquid–liquid systems at different temperatures are presented. The model predictions are in good agreement with the experimental data.