Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

Experimental data over the temperature range from 263 to 363 K are presented on the air-liquid interfacial tension and 0.1 MPa densities for four ionic liquids with the tris(pentafluoroethyl)trifluorophosphate (FAP) anion and with the 1-(2-Methoxyethyl)-1-methylpyrrolidinium, 1-(2-Methoxyethyl)-1-methylpiperidinium, N-(3-Hydroxypropyl)pyridinium, and 1-(2-Hydroxyethyl)-3-methylimidazolium cations. The surface tension data were obtained by the Wilhelmy plate method with an estimated combined expanded uncertainty at 0.95 confidence level of 0.2 mN m-1. The reported density data were obtained using a single-sinker buoyancy method with an estimated expanded combined uncertainty at 0.95 confidence level 0.8 kg m-3 (4.6 x 10-4.rho). The Kruss K100MK2 tensiometer was used to determine the surface tension and buoyancy forces. A value of 224.79 cm3 mol-1 follows for the FAP anion contribution to the ionic liquids molar volume at 298.15 K and 0.1 MPa from the group contribution analysis of the density data. In contrast to the common organic liquids, the studied ionic liquids show a negative value of the temperature derivative of the isochoric thermal volume expansion coefficient in the studied temperature interval.