Viscosity, Interfacial Tension, Self-Diffusion Coefficient, Density, and Refractive Index of the Ionic Liquid 1-Ethyl-3-methylimidazolium Tetracyanoborate as a Function of Temperature at Atmospheric Pressure

Abstract

Thermophysical properties of the ionic liquid (IL) [EMIM][B(CN)4] (1-ethyl-3-methylimidazolium tetracyanoborate) were investigated both by conventional techniques and by surface light scattering (SLS) at atmospheric pressure. The density was measured between (283.15 and 363.15) K with a vibrating U-tube densimeter. An Abbe refractometer was used for the measurement of the refractive index in the range from (283.15 to 313.15) K. Self-diffusion coefficients for the cation and anion were measured by nuclear magnetic resonance (NMR) spectroscopy from (273.15 to 318.15) K. The interfacial tension was obtained from the pendant drop technique at 297.04 K. Based on this datum and the temperature dependence of density, the interfacial tension for all relevant temperatures was estimated via an appropriate prediction model. For the IL studied within the present work, the quantity directly accessible by SLS at low temperatures was the ratio of dynamic viscosity to interfacial tension. Combining the results from SLS w...