[1-Ethyl-2,3-dimethyl-imidazolium][ethylsulfate]-based aqueous two phase systems: New experimental data and modeling

[Display omitted] •Aqueous two phase partitioning system containing [emmim][eSO4] ionic liquid is introduced.•Effect of salts and temperature on the phase forming of the IL–salt ATPSs are assessed.•The salts have significant effect on the phase separation while the temperature effect is negligible.•A symmetrical activity coefficient model comprising of PDH and Wilson-NRF equations is applied.•The model successfully correlated all the data with an overall ARD of 0.0710. In this work, a new type of ionic-liquid-based aqueous two phase systems namely [1-ethyl-2,3-dimethylimidazolium][ethylsulfate] ([emmim][eSO4])–salt is introduced and investigated. Effect of various inorganic salts Na2CO3, Na2SO4 and K2HPO4 on the phase forming ability of [emmim][eSO4] at different temperature (T/K=288.15, 298.15 and 313.15) are assessed. The results indicate that the effect of temperature in comparison with salt effect is negligible and the ability of the salts to phase separation of the [emmim][eSO4]-based aqueous two phase systems, follows the order Na2CO3≥Na2SO4>K2HPO4. Moreover, the experimental data are successfully correlated using a new thermodynamic model based on symmetrical activity coefficient model with an overall average relative deviation (ARD) of 0.0710. In this model, the long-range contribution is accounted by Pitzer–Debye–Hückel (PDH) equation while the short-range contribution is considered by nonelectrolyte Wilson non-randomness-factor (Wilson-NRF) model. The result of the correlation shows that the applied model could successfully correlate the phase behavior of the ionic liquid-based aqueous two phase systems.