Viscosity, Interfacial Tension, Density, and Refractive Index of Ionic Liquids [EMIM][MeSO₃], [EMIM][MeOHPO₂], [EMIM][OcSO₄], and [BBIM][NTf₂] in Dependence on Temperature at Atmospheric Pressure

Abstract

This work represents a continuation of former investigations, where viscosity, interfacial tension, density, and refractive index of ionic liquids (ILs) [EMIM]and [OMA][NTf 2 ] (trioctylmethylammonium bis(trifluoromethylsulfonyl)imide) were studied. Here, the ILs [(1-butyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide) were investigated again both by conventional techniques and by surface light scattering (SLS). An Abbe refractometer was used for the measurement of the refractive index in the range of (283.15 to 313.15) K with an expanded uncertainty (k ) 2) of about 0.0005. The density was measured between (273.15 and 313.15) K with a vibrating tube densimeter and an expanded uncertainty (k ) 2) of about 0.02 %. The interfacial tension was obtained from the pendant drop technique at a temperature of 293.15 K with an expanded uncertainty (k ) 2) of 1 %. On the basis of this datum and the temperature dependence of density, the interfacial tension for all relevant temperatures was estimated via an appropriate prediction model. For the ILs studied within this work, at a first-order approximation, the quantity directly accessible by SLS was the ratio of dynamic viscosity to surface tension. Combining the results from SLS with values for density and interfacial tension from conventional methods, the dynamic viscosity could be obtained from (273.15 to 333.15) K with an estimated expanded uncertainty (k ) 2) of less than 3 %. Besides a comparison with the literature, the major aim of this work was to point out the influence of variations of the anion on thermophysical properties of [EMIM] + -based ILs. In addition, the effect of different cations was studied in ILs with the [NTf 2 ]anion. ILs with equal cations and similar anions can still exhibit different properties, which is interpreted with relevant molecular interactions.

Thermal Conductivity of Ionic Liquids: Measurement and Prediction

“…As infrared refractive-index data n for the ILs used here are not available in the literature and cannot be easily measured, the values at the sodium vapor line for the mean temperature of all thermal-conductivity measurements of 313.15 K provided in our former studies [28,34] …”

“…Figure 6b shows a logarithmic plot of λ c M/η as a function of M at 293.15 K and atmospheric pressure for the ten ILs studied in this work. For this, data for the dynamic viscosity were used from our previous work [28,34] 3 ]. For these ILs, corresponding data of 89.26 mPa · s at 293.15 K, 93 mPa · s at room temperature, and 18 mPa · s at 295.15 K were adopted from [41], http://www.basionics.com/en/ ionic-liquids/products/data/bc01.htm, and [42], respectively.…”

“…For the latter, densities were measured within this study using the vibrating-tube method with an estimated expanded relative uncertainty (k = 2) of less than ±0.02 %. More details on the method and the used instrument (DMA 5000, Anton Paar) can be found in [28,36]. The measurements were performed at atmospheric pressure starting from (273.15 to 363.15) K in steps of 5 K. The density data are given in Table 6 and were correlated with second-order polynomial functions,…”

Measurements of activity coefficients at infinite dilution for organic solutes and water in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate

“…The comparisons with previouslypublished [EMIM]-based ILs are presented. The density of the IL as a function of temperature was also determined and compared to the literature values [10]. The thermodynamic properties obtained at the chosen temperature T = 328.15 K were analysed to describe the intermolecular interactions and to identify the potential of [EMIM][MeSO 3 ] to be utilised as a new solvent in the separation processes.…”

A group contribution method to estimate the densities of ionic liquids

“…For example, in the method of Refs. [5,8], even [C 7 mim][NTf 2 ] (1-heptyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide) and [bbim][NTf 2 ] (1-butyl-3-butyl-imidazolium bis(trifluoro-methylsulfonyl)imide) were estimated to have the same density at room temperature and atmospheric pressure, while actually they are 1.3528 g Á cm À3 [14] and 1.3445 g Á cm À3 [15], respectively. And in this work, in order to make it work on ionic liquids with different centers the interaction is distinguished by the complexity of substitutes rather than the position of the substitutes.…”