Thermophysical Properties of the Pure Ionic Liquid 1-Butyl-1-methylpyrrolidinium Dicyanamide and Its Binary Mixtures with Alcohols

Abstract

Experimental density, speed of sound, viscosity, and refractive index data for the pure ionic liquid 1-butyl-1-methylpyrrolidinium dicyanamide, [BMpyr][dca], are reported from T = (293.15 to 343.15) K, together with the molar isobaric heat capacity from T = (293.15 to 333.15) K. Moreover, a thermal analysis was carried out for the pure ionic liquid using a differential scanning calorimetry. The density, speed of sound, refractive index, and molar isobaric heat capacity data were fitted to a simple polynomial (first and/or second order), while viscosity data were fitted to the Vogel–Fulcher–Tamman (VFT) equation. From the experimental density values, the thermal expansion coefficient was also calculated. For the binary systems {1-propanol, or 2-propanol, or 1-butanol + [BMpyr][dca]}, density, speed of sound, and refractive index data were also measured over the whole composition range at T = (298.15, 313.15 and 328.15) K and p = 0.1 MPa. From these data, the excess molar volumes and excess molar isentropic compressions were calculated and satisfactorily fitted to the Redlich–Kister equation. Finally, the obtained results are discussed in terms of interactions and structure factors in these binary mixtures.