Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The properties of mixtures of ionic liquids and water are very important for many applications. One key application is their use as absorbents in absorption refrigeration cycles, replacing water + LIBr and water + ammonia systems. As a possible mixture, the system [Bmpyr][dca] + H2O was studied, as the available data are scarce. Measurements of density, speed of sound, viscosity, and surface tension of [Bmpyr][dca] + H2O were made for seven molar compositions between 288.15 K and 333.15 K. The uncertainty of the density values is 0.07 kg*m 3, while that of the speed of sound was found to be 0.3 m*s 1. Viscosity measurements have an uncertainty of 1.4 %, while the surface tension values have an uncertainty lower than +-0.6 mN*m 1. All the measurement were measured at atmospheric pressure and are reported to 0.1 MPa +- 1 kPa. From density data, isobaric molar expansions were calculated and from combined density and speed of sound data, isentropic molar compressions were also obtained. Finally, excess molar volumes, excess molar isobaric expansions and excess molar isentropic compressions were derived and fitted to Redlich Kister polynomial equations. Estimated surface entropy and enthalpy were calculated. Regarding the viscosity measurements, the [Bmpyr][dca] was found to be a Newtonian fluid and the deviations of the viscosity of the mixtures from ideality were found to be very dependent on the molar fraction of water. Observed changes of the several properties with composition and temperature were analyzed in terms of intermolecular interactions and changes in structure patterns. From the results obtained, it can be concluded that this mixture has adequate thermophysical properties for absorption refrigeration applications.