Thermodynamic Properties of Imidazolium-Based Ionic Liquids:  Densities, Heat Capacities, and Enthalpies of Fusion of [bmim][PF₆] and [bmim][NTf₂]

Abstract

Experimental densities, isobaric heat capacities, and enthalpies of fusion for one sample of 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6], and two samples of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][NTf2], are reported. Data were obtained at atmospheric pressure and, in the case of the density and the heat capacity, within the temperature intervals (283.15 to 323.15) K and (278.15 to 333.15) K for [bmim][PF6] and [bmim][NTf2], respectively. A critical analysis of the effect of impurities on the measured thermodynamic properties is performed.

Thermal Properties of Ionic Liquids and Ionanofluids

“…With the exception of the data reported by Kabo and co-workers (Kabo et al, 2004) which were obtained using a heat bridge calorimeter, all the remaining data were obtained using DSC. Our data agrees with the data of (Troncoso et al, 2006) between 0.4 and 0.6% and with (Kabo et al, 2004) between 0.8% and 1.2%. Results with deviations greater than ± 2% are not included.…”

“…Figure 7 shows the variation of heat capacity with temperature together with the results obtained from various research groups (Holbrey et al, 2003;Kabo et al, 2004;Fredlake et Table 7. Coefficients of equation (7) Fig . -Rebelo et al, 2004;-Kim et al, 2004;-Fredlake et al, 2004;-Waliszewski et al, 2005;-Van Valkenburg et al, 2005;-Garcia-Miaja et al, 2008;-Garcia-Miaja et al, 2009) -Holbrey et al, 2003;-Kabo et al, 2004;-Fredlake et al, 2004;-Troncoso et al, 2006) 2004; Troncoso et al, 2006). With the exception of the data reported by Kabo and co-workers (Kabo et al, 2004) which were obtained using a heat bridge calorimeter, all the remaining data were obtained using DSC.…”

Thermophysical Properties of 1-Butyl-3-Methylimidazolium Bis(trifluoromethylsulfonyl)imide at High Temperatures and Pressures

“…The maximum deviation of these at T = 414.92 K and p = 1 MPa is Δρ/ρ = 0.079%. Various heat capacity values at constant ambient pressure c p (p 0 ,T) are available in the literature (Krummen et al, 2002;Fredlake et al, 2004;Tokuda et al, 2006;Troncoso et al, 2006;Shimizu et al, 2007;Ge et al, 2008;Blokhin et al, 2008;Katsuta et al, 2010). Our results are in good agreement with the values from Tokuda et al (2006), Shimizu et al (2007) and Ge et al (2008).…”

“…The Troncoso et al, (2006) showed Δρ/ρ = 0.0769% average deviation and they are also smaller than our values with a maximum deviation of Δρ/ρ = -0.0966% at T = 333.15 K. Jacquemin et al (2007) presented ten density values at ambient pressure and various temperatures, which have Δρ/ρ = ±0.0516% average deviation and these values are higher than our measured values. The maximum deviation is Δρ/ρ = 0.0726% at T = 293.49 K.…”

“…The deviations from the literature values are presented in Figure 5. Troncoso et al (2006) showed Δc p /c p = ±0.08% average deviation. These values are higher than our values at lower temperatures and, after T = 298.15 K, the literature values are smaller than our values.…”