Liquid-liquid equilibria for (polypropylene glycol 400 based magnetic ionic liquids + inorganic salts) aqueous two-phase systems at 298.15 K

Abstract

Two polypropylene glycol 400 (PPG400) based temperature-sensitive magnetic ionic liquids were successfully used to construct the temperature-sensitive magnetic ionic liquid aqueous two-phase systems (MILATPs). This temperature-sensitive MILATPs combined temperature-controlled recovery and the advantages of a MILATPs and is showing great potential in the field of extraction and separation. In this work, aqueous two-phase equilibrium data of the temperature-sensitive MILATPs ([HOPPG400BMIM][Tempo-OSO3] + K3PO4/K2CO3/ Na2CO3 + H2O systems and [BMIMPPG400BMIM][Tempo-OSO3]2 + K3PO4/K2CO3/ Na2CO3 + H2O systems) were determined at 298.15 K under 0.1 MPa. Three common empirical equations including Merchuk equation were adopted to fit the experimental binodal data with satisfactory correlation performances. Inorganic salts screening demonstrated that K3PO4 and K2CO3 have better phase-forming ability than Na2CO3. Morever, [HOPPG400BMIM][Tempo-OSO3] has a better phase-forming ability than [BMIMPPG400BMIM][Tempo-OSO3]2. Subsequently, tie line data for systems containing K3PO4 or K2CO3 were determined and correlated by two empirical equations with satisfactory correlation performances. Furthermore, the temperature- controlled recovery of temperature-sensitive magnetic ionic liquid was ideally realized simply by heating. All these experimentally measured liquid–liquid equilibrium data and the theoretical correlations can provide valuable reference for future application in the field of extraction and separation.