A cyclic voltammetric technique for the detection of micro-regions of bmimPF6/Tween 20/H2O microemulsions and their performance characterization by UV-Visspectroscopy

Abstract

As green solvents, ionic liquids (ILs) can be substitutes for traditional organic solvents, and form useful microemulsions with water. Microemulsions consisting of the IL, 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF₆), the non-ionic surfactant Tween 20 and water were formed at 30.0 °C, and the phase behavior of the ternary system was investigated. Three regions of the microemulsions: water-in-bmimPF₆ (W/IL), bicontinuous, and bmimPF₆-in-water (IL/W) were identified by cyclic voltammetry using potassium ferrocyanide K₄Fe(CN)₆ as an electroactive probe. The polarity of the microemulsion environment was investigated by UV-Visible spectroscopy using methyl orange as a probe. Use of the ionic compound K₃Fe(CN)₆ in UV-Visible measurements revealed that the bmimPF₆/Tween 20/H₂O microemulsions could solubilize salt species into the microemulsion droplets. Moreover, the solubilization of riboflavin in the microemulsions was also shown by UV-Visible spectra. These results show that these IL-based microemulsions have potential in the production of metal nanomaterials, in biological extractions or as solvents for enzymatic reactions.