A study on the viscosity, density, and derivative properties of 1-alkyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imides with benzo-15-crown-5 binary mixtures

The essential factors that affect the interfacial mass transfer rate of crown ether–ionic liquid systems are studied by examining the physicochemical properties of mixtures of ionic liquids with benzo-15-crown-5. In the present work, the 1-alkyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imides ionic liquids ([C2MIm][NTf2], [C3MIm][NTf2], [C4MIm][NTf2], and [C5MIm][NTf2]) are adopted as the solvent and benzo-15-crown-5 is used as the solute. A series of binary mixtures of the ionic liquid and benzo-15-crown-5, with different molar fractions of ionic liquids, is formulated by the weight method. The viscosity and density are determined for four binary mixtures of ionic liquid and benzo-15-crown-5 at atmospheric pressure in a temperature range of 298.15 to 343.15 K. The values obtained for viscosity and density are fitted with empirical equations, and the energy barrier, a-constant, and the isobaric thermal expansion coefficient are all calculated. Interactions between the ionic liquid and the solute benzo-15-crown-5 are analyzed, and the above properties are discussed by comparison with systems in which different solutes are present in the same ionic liquid. It is found that interactions between the ionic liquid and benzo-15-crown-5 in the mixtures are more intense than in mixed systems composed of ionic liquids and other solutes.