Isobaric and Isochoric Heat Capacities as Well as Isentropic and Isothermal Compressibilities of Di- and Trisubstituted Imidazolium-Based Ionic Liquids as a Function of Temperature

Abstract

The isobaric and isochoric heat capacities of six disubstituted imidazolium-based ionic liquids with different anions and two trisubstituted imidazolium-based bis-(trifluoromethylsulfonyl)imides were determined at atmospheric pressure in the temperature range from 293.15 to 323.15 K. The isobaric heat capacities were determined using differential scanning calorimetry. The isochoric heat capacities were determined indirectly by means of the acoustic method from the speed of sound and density measurements. Also, other connected with the speed of sound quantities such as isentropic and isothermal compressibilities as well as internal pressures were determined. The highest compressibilities show both trisubstituted imidazolium-based bis(trifluoromethylsulfonyl)imides whereas 1-ethyl-3-methylimidazolium thiocyanate shows the lowest compressibility. The critical comparison of the isobaric heat capacity data with the available literature data makes possible a recommendation of the most reliable heat capacity values. Analyzed predictive capability of two heat capacity models based on the group contribution method is poor in the case of the [C(CN) 3 ] − anion. Additionally, based on the speeds of sound, the thermal conductivities were calculated using a modified Bridgman relation and compared with values estimated by a group contribution method. Here, the worst results are obtained in the case of [SCN] − anion.

Thermophysical Properties of IoNanofluids Composed of 1-ethyl-3-methylimidazolium Thiocyanate and Carboxyl-functionalized Long Multi-walled Carbon Nanotubes

“…The density of the IL and INFs was measured within the temperature range from 25 • C to 50 • C. The experimental values are collected in Table 4 and presented in Figure 5. The density of pristine [C 2 C 1 im][SCN] obtained in this work at 25 • C is in a very good agreement with the literature data [5,[9][10][11][12][13][14] (Table 1). The relative deviations, RDs (RD/% = 100•(ρ this work − ρ lit )/ρ this work ), are equal to −0.55% [14], −0.08% [12,13], 0.02% [10,11], 0.05% [9], and 0.08% for result reported recently by us [5].…”

“…Literature ρ (kg•m −3 ) 1116.1 ± 0.1 1115.20 [5], 1115.5 [9], 1115.9 [10,11], 1117 [12,13], 1122.26 [14] η (mPa•s) 22.70 ± 3.9% 22.68 [15], 22.64 [5], 23.77 [16], 23.79 [17], 24.50 [12]…”

Temperature and Pressure Dependence of the Viscosity of the Ionic Liquid 1-Butyl-3-methylimidazolium Acetate

“…Water analysis is done by Karl Fischer coulometry. Almeida et al used standard Hydranal, whereas Zorębski et al , used methanol-free reagents as in this work. The other groups cited (Table ) did not specify whether or not methanol-free reagents were employed.…”

“…Deviations of experimental and literature densities from values predicted by eq as a function of temperature, T . Symbols: IoLiTec sample, this work, blue filled inverted triangle, sample 1 as received [10 6 × w (H 2 O) = 2300]; blue filled diamond, sample 2 as received [10 6 × w (H 2 O) = 3700]; blue filled triangle, sample 1 dried isopiestically over Na [10 6 × w (H 2 O) = 1457]; blue filled circle, sample 1 dried under vacuum [10 6 × w (H 2 O) = 1180]; blue filled box, sample 2 dried under vacuum [10 6 × w (H 2 O) = 1100]; literatureother IoLiTec samples: solid triangle, Almeida et al [10 6 × w (H 2 O) = 850]; solid diamond, Hiraga et al [10 6 × w (H 2 O) = 250]; solid inverted triangle, Zorębski et al [10 6 × w (H 2 O) = 1512); solid circle, Lepre et al [10 6 × w (H 2 O) = 1600]; literatureFluka sample: open diamond, Tariq et al [10 6 × w (H 2 O) < 70]; literatureBASF sample: asterisk, Araújo et al [10 6 × w (H 2 O) < 4700]; literatureSigma-Aldrich samples: open triangle, Kanakubo et al [10 6 × w (H 2 O) = 3500]; open box, Haghtalab and Shojaeian [10 6 × w (H 2 O) = 15 000]; open circle, Safarov et al [10 6 × w (H 2 O) = 300]; open inverted triangle, Shaahmadi et al [10 6 × w (H 2 O) < 100]; literaturelaboratory-synthesized samples: Pandit et al [10 6 × w (H 2 O) < 50], off scale, 37 mg·cm –3 ; cross, Xu et al [10 6 × w (H 2 O) = 99).…”

“…The viscosity is an important property for industrial and other applications. It is also useful for the theoretical assessment of other transport properties and for practical applications in heat capacity and other physical property measurements . No determinations at high pressure appear to have been reported previously.…”