Phase Equilibrium, Volumetric, and Interfacial Properties of the Ionic Liquid, 1-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)amide and 1-Octene

Abstract

Biphasic systems involving ionic liquids (ILs) form the basis of many applications in extractions and reactions. In this work, the liquid−liquid phase equilibrium, density, molar volume, excess molar volume, and interfacial and surface tensions are measured for saturated and subsaturated mixtures of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([HMIm][Tf 2 N]) and 1-octene at four different temperatures, (10, 25, 50, and 75) °C. Many of the properties of the IL phase change significantly with the increasing concentration of 1-octene. The nonrandom two-liquid (NRTL) activity coefficient model was utilized to model the mutual solubility of two liquids. 1-Octene is fairly soluble in the [HMIm][Tf 2 N], but the IL solubility in the 1-octene is very small. The excess molar volume for the mixture of ILs and 1-octene is slightly negative for all isotherms and becomes more negative with an increase in temperature. The air−liquid surface tension decreases with increasing 1-octene concentration, and the saturated [HMIm][Tf 2 N] + 1-octene interfacial tension decreases significantly at higher temperatures.