Isobaric thermal expansivity behaviour against temperature and pressure of associating fluids

Dependence against Temperature and Pressure of the Isobaric Thermal Expansivity of Room Temperature Ionic Liquids

“…Isobaric thermal expansivity for the RTILs was obtained by using a Micro DSCII microcalorimeter from Setaram coupled with a Ruska 7610 pressure controller. − The method for determining α p is based on recording the heat exchanging between the cell which contains the RTIL and the calorimetric block, which appears because of a pressure variation over the sample. α p is thus determined using the next equation: α p = − 1 V T d′ Q d p where V , T , and (d′ Q )/(d p ) denote volume, temperature, and variation of the heat introduced in the system against change in pressure, respectively.…”

“…As a consequence, research about the physical properties of these compounds has received great attention in the last few years. − Most of the effort was spent in the study of physical properties of RTILs at atmospheric pressure, although in the last few years, there have been some works devoted to characterize the behavior against p and T , of several magnitudes, with the density ρ being the most widely studied. − As a result, it was concluded that the RTILs density dependencies against T and p , given by the isobaric thermal α p expansivity and isothermal compressibility κ Τ , differ significantly from those of other solvents. These differences were observed not only in the α p and κ Τ values themselves but also in the behavior of these magnitudes against temperature and pressure: there are several works , in which a negative temperature dependency for α p over the whole pressure range is shown, where this behavior is not usually found for organic solvents at moderate pressures. − Moreover, by checking the α p literature data, − it seems to be that this is not an isolated case, but the rule for RTILs.…”

“…It is the aim of this work to provide more experimental data of α p against temperature and pressure for RTILs. Isobaric thermal expansivity was directly determined through a calorimetric method − in the range of (278.15 to 348.15) K and (5 to 50) MPa for a set of RTILs, selected to represent some of the most widely studied anions and cations: 1-butyl-3-methylpyridinium tetrafluoroborate [C 4 mpyr][BF 4 ], 1-ethyl-3-methylimidazolium tetrafluoroborate [C 2 mim][BF 4 ], 1-hexyl-3-methylimidazolium tetrafluoroborate [C 6 mim][BF 4 ], 1-octyl-3-methylimidazolium tetrafluoroborate [C 8 mim][BF 4 ], 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C 2 mim][NTf 2 ], and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C 6 mim][NTf 2 ] are analyzed. The reported data are compared with literature, obtained from the experimental measure of density, − and the obtained α p values as well as their behavior against temperature and pressure are qualitatively discussed and related to the chemical nature of the anion and cation.…”

Isobaric Thermal Expansivity for Ionic Liquids with a Common Cation as a Function of Temperature and Pressure

“…[5][6][7][8][9][10][11][12][13] It was found that density of RTILs is usually between (1000 and 2000) kg • m -3 , whereas its dependencies against temperature and pressure (given by the isobaric thermal expansivity R p and isothermal compressibility κ T ) are significantly milder than those found for common organic solventssboth thermodynamic coefficients present values about a half of those of molecular liquids. In addition, some studies 6,7 point to the fact that R p of RTILs presents a negative temperature dependency, opposite to that found for usual organic solvents at moderate pressures, [14][15][16][17][18][19][20][21] although it would be desirable to have some more evidence to confirm this anomalous behavior. It is the aim of this work to contribute to the knowledge of the behavior of R p against temperature and pressure for RTILs.…”

“…It is the aim of this work to contribute to the knowledge of the behavior of R p against temperature and pressure for RTILs. To this end, R p was determined through a calorimetric method [19][20][21][22] SO 3 ], and methylsulfate, [MeSO 4 ], were the chosen anions. The reported data are compared with the literature, obtained from experimental measure of density, [5][6][7][8][9][10][11][12][13] and finally, the R p values as well as their behavior against temperature and pressure are qualitatively discussed in terms of the chemical nature of the anion.…”