Experimental Measurement of Physical, Transport, and Optical Properties of Binary Mixtures of N-Hexyl Pyridinium Nitrate [HPy][NO3] Ionic Liquid with Water, Ethanol, and Acetonitrile at 298.15 K and 101 kPa

Abstract

We have conducted the first investigation of the thermophysical and transport properties of N-hexyl pyridinium nitrate [HPy][NO3], a room-temperature ionic liquid, in combination with water and the organic solvents, ethanol, and acetonitrile in the form of binary mixtures, at 298.15 K and 101 kPa. The densities, viscosities, and refractive indices of the binary mixtures were measured, and the experimental values were used to calculate the derived properties. To examine the volumetric properties of the binary mixtures, the apparent molar volumes were calculated from experimental densities and correlated using both the Redlich–Mayer and Pitzer models. It was found that the dielectric constant and polarity of the solvents had significant effects on the ion–solvent interactions. The viscosities and refractive indices of the mixtures are reported; the B-coefficient of the Jones–Dole equation, and the molar refractive indices determined using the Lorentz–Lorenz equation were calculated. Values of the standard deviations between the calculated and experimental data were determined using the linear least-squares method. Finally, the results were used to shed light on the structure making/breaking effect of ions in the binary mixtures.