TX-100/Water/1-Butyl-3-methylimidazolium Hexafluorophosphate Microemulsions

Abstract

Both ionic liquids and water are typical green solvents. In this work, the phase behavior of the ternary system consisting of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), TX-100, and water was determined at 25.0 °C. The water-in-bmimPF6, bicontinuous, and bmimPF6-in-water microregions of the microemulsions were identified by cyclic voltammetry method using potassium ferrocyanide K4Fe(CN)6 as the electroactive probe. Dynamic light scattering (DLS) and the UV−vis method were used to characterize the microemulsions. It was demonstrated that the hydrodynamic diameter (Dh) of the bmimPF6-in-water microemulsions is nearly independent of the water content but increases with increasing bmimPF6 content due to the swelling of the micelles by the ionic liquid. The UV−vis further confirmed the existence of water domains in the water-in-bmimPF6 microemulsions, and the salt potassium ferricyanide K3Fe(CN)6 could be dissolved in the water domains.