An important element in the work-up of brines is the separation of different ions present. Usually, energy consuming technologies, such as multi-stage evaporation, reverse osmosis, crystallization, and nanofiltration, are used to bring the composition of the brine to the required specification. Fractionation of salts by liquid¿liquid extraction using thermo-responsive polymers is a novel concept. In the current study we have evaluated the fractional extraction of sodium chloride from brines containing sodium sulfate as well. Four different polymers (Dehypon LS 54, PPG 425, Pluronic L31 and Triton X ¿ 15) have been used. The quaternary systems of these polymers with water, sodium chloride and sodium sulfate have been obtained at 283.15 K and 298.15 K. From experiments at 298.15 K, it was concluded that the polymer Dehypon LS 54 showed the most interesting combination of extracted sodium chloride yield and selectivity of sodium chloride over sodium sulfate. The polymer losses to the feed (brine) phase were limited. Collected extract phases were subjected to a temperature increase to 323.15 K, 333.15 K, 343.15 K, and 353.15 K in order to study the polymer recovery by temperature induced phase splitting. It was found that at higher temperature the miscibility gap increased strongly and limited amounts of polymer remained in the aqueous phase.@en

tLiquid¿liquid extraction using thermoresponsive polymers as solvents in aqueous two phase systemsfollowed by induced phase separation to recover the polymers is a potential technology for water¿saltseparations. Here we report for seven polymers on their ternary systems containing water, sodium sulfateand the (block co)poly ether. Equilibrium data were measured at 298.15 K and 313.15 K and atmosphericpressure. Empirical equations have been used to correlate the experimental equilibria for both temper-atures separately and the semi-empirical NRTL model has been applied with a temperature dependentparameter to describe the complete dataset for both temperatures together. Model predictions were ingood agreement with the experimental data.@en

tLiquid¿liquid extraction using polymers followed by induced phase separation is a potential energyreducing technology for water¿salt separation. Ternary equilibrium data have been determined andreported for the (block co)poly ethers¿sodium chloride¿water systems at two different temperaturesat 298.15 K and 313.15 K and atmospheric pressure. The experimental data were correlated with theNRTL model, and the obtained binary interaction parameters to describe the ternary liquid¿liquid sys-tems at different temperatures are presented. The model predictions are in good agreement with theexperimental data.@en