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The purpose of this comment is to express some concern regarding the viscosity deviations and excess Gibbs energy of activation for viscous flow for binary mixtures in recent JCT papers. Compared to the viscosity deviations used in their papers, the relative viscosity of mixture, η r , is put forward in this paper, because it is related to excess Gibbs energy of activation for viscous flow. On a basis of the Eyring equation of viscosity, a new relationship was set up between the relative viscosity of the mixture and the corresponding excess Gibbs energy of activation for viscous flow. The new relationship can express the excess Gibbs energy of activation for viscous flow exactly, which is available to study the interaction of mixtures. [ABSTRACT FROM AUTHOR]

• Solubility data of chlorinated phenols in ionic liquids is reported for the first time. • The effect of temperature on the solubility data was investigated. • The solubility of the chlorophenols depended on the structure of ionic liquids. • COSMO-RS and NRTL model were used to predict and correlate the experimental data. Chlorophenols (CPs) are synthetic chemicals that are generated and used widely by different industries such as textile, pharmaceutical, metallurgic, oil, and pulp and paper manufacturing. Except water, most of the solvents used in these industries are volatile and toxic. Therefore, there is an imminent need for replacing these solvents by solvents that have less negative impact on the environment. In addition, CPs are considered as hazardous pollutants due to their resistance to biodegradation and persistence in the environment. Their toxic effects are severe including DNA damage, endocrine disruption, cytotoxicity, mutagenicity, and carcinogenicity. Hence, the water contaminated by CPs must be treated before being released to the environment. Ionic liquids (ILs) are molten salts that are liquid below 100 °C, which have been used as solvents for many processes including liquid-liquid extraction and as electrolytes in electrochemical devices. ILs are characterized by negligible vapor pressure and non-flammability. These compounds are liquid over a wide range of temperatures; possess high thermal and chemical stability. ILs are being used as media for many reactions to reduce the negative impact of traditional solvents on the environment. In addition, using ILs as green solvents in water treatment has become a research hotspot. Solubility data of CPs in ILs is important for assessing the potential use of ILs as reaction media and in water treatment, but relevant data for ILs are scarce. To our best knowledge, no solubility data of chlorophenols in ILs were reported in the literature. Thus, in this study, the solubility of 3-chlorophenol (3-CP), 2,5-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP) in six hydrophobic bis(trifluoromethylsulfonyl)imide based ILs at 25 °C, 35 °C and 45 °C was investigated. It was found that the solubility of 3-CP in all studied ILs at 25 °C was greater than 70 wt%, thus the solubility measurements of 3-chlorophenol in the studied IL were stopped at 70 wt% and further measurement was not conducted. The solubility of other CPs in all studied ILs decreased with increasing the number of chlorine atoms in the CP and increased with the increase in temperature, but the degree of increase depended on the structure of both the IL and chlorinated phenol. In general, it was found that the tested chlorophenols have substantial solubility in pyridinium and imidazolium-based ILs. In addition, the non-random two-liquid model (NRTL) and Conductor-like Screening Model for Real Solvents (COSMO-RS) models were applied to predict the solubility of chlorophenols in all ILs used in this study. There was a good quantitative and qualitative agreement between experimental and calculated solubility data in most of the cases. [ABSTRACT FROM AUTHOR]

Highlights • Errors are discovered in the published equation coefficients for NRTL model. • Published equation coefficients fail to describe the reported mole fraction solubility. • RTTL equation coefficients were re-analyzed. Abstract Errors were discovered regarding the published equation coefficients of Alevizou and co-workers [J. Chem. Thermodyn. 62 (2013) 69–78] for mathematically describing the solubility of p -coumaric and caffeic acid in ionic liquids and organic solvents using the NRTL model. The curve-fit coefficients fail to describe the reported solubility data in the authors' published paper. The equation parameters were re-analyzed based on the reported solubility data. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Five choline based ionic liquids with different chelating anions are synthesized and characterized by IR, NMR, and TGA. • Density and viscosity measurements of pure ionic liquids were performed. • The structural organization proved with computational simulations. • High density and viscosity as a direct effect of cations and anions interactions and high coordination tendency of anions. Abstract In this paper, physicochemical characterization of newly synthesized choline based ionic liquids with five different chelating anions were examined. The ionic liquids (ILs): cholinium- l -lactate, [Ch][Lac], cholinium-picolinate, [Ch][Pic], cholinium-anthranilate, [Ch][Ant], cholinium-oxyquinolinate, [Ch][oQ], and cholinium-diethylenetriaminepentaacetate, [Ch] 3 [DTPA], were prepared for the first time and their structures were confirmed by IR and 1H and 13C NMR spectra. Also, thermogravimetric analysis (TGA) was applied to determine their thermal stabilities. Based on the measured density values and viscosity in the temperature range from (293.15 to 323.15) K and calculated values of thermal expansion coefficients and activation energy of viscous flow, as well as of computational simulations, the interactions and structures of the investigated ionic liquids were discussed. [ABSTRACT FROM AUTHOR]

Highlights • A robust thermodynamic consistency test of phase equilibrium data is described. • A versatile vpt equation of state is employed. • PTx data of mixtures containing a gas solute and an ionic liquid are analyzed. • Applications of the method by several researchers around the world are also discussed. • Recommendations on how to apply it to different types of mixtures is provided. Abstract In this paper the advances done by our research group on thermodynamic consistency tests of low and high-pressure phase equilibrium data of binary mixtures are reviewed and new applications of a versatile equation of state (EoS) to test phase equilibrium data of gases + ionic liquid mixtures are explored. The consistency method has been especially designed to analyze data sets of phase equilibrium data that do not cover the whole concentration range and relies on the accurate modelling of the data with and EoS to then apply the Gibbs-Duhem (GD) equation. The accurate and general VPT equation of state proposed in 1990 by one of the authors is employed, including modern mixing and combining rules. The proposed EoS-GD method allows analyzing experimental data and clearly determining the thermodynamic consistency or inconsistency of the data. Applications of the method by several researchers around the world are also discussed and recommendations on how to apply it to different types of mixtures is provided. [ABSTRACT FROM AUTHOR]

In the present paper, we report new experimental data on density ( ρ ) and speed of sound ( u ) in binary liquid mixtures of 1-ethyl-3-methylimidazolium hydrogen sulphate, [emim][HSO 4 ] with polar protic solvents ethanol (EtOH) and 1-propanol (n-PrOH) and aprotic solvent, dimethyl sulphoxide (DMSO) over the complete range of mole fraction at 298.15 K ≤  T ≤ 313.15 K, every 5 K, and 0.1 MPa pressure. The mixing behaviour of the binary systems of [emim][HSO 4 ] with EtOH, n-PrOH, and DMSO has been studied by computing the excess volumes ( V E ) and excess isentropic compressibilities ( κ s E ) utilizing the measured densities ( ρ) and speeds of sound ( u ). Further, the excess functions V E and κ s E are correlated with mole fraction, using Redlich-Kister equation to derive the fitting parameters. For the systems studied, the excess thermodynamic properties ( V E and κ s E ) are found to be negative over the whole range of composition at investigated temperatures. Also, the experimental results are discussed in terms of ion-ion, ion–dipole, hydrogen bonding interactions and interstitial accommodation between component molecules in the binary liquid mixtures. Moreover, the temperature dependence of the physicochemical and excess properties has been studied. [ABSTRACT FROM AUTHOR]

This paper explores the thermodynamic behavior of aqueous solutions of four ionic liquids (ILs), namely 1-butyl-1-methylpyrrolidinium dicyanamide [BMPYR][DCA], 1-butyl-3-methylimidazolium dicyanamide [BMIM][DCA], 1-butyl-1-methylpyrrolidinium 1,1,2,2-tetrafluoroethanesulfonate [BMPYR][TFES], and 1-butyl-3-methylimidazolium 1,1,2,2-tetrafluoroethanesulfonate [BMIM][TFES]. The ionic liquids with [TFES] – anion (tetraflates) have been scarcely researched so far and therefore were characterized here with 1 H NMR spectroscopy and DSC calorimetry. In all four systems studied, water activity was systematically measured, the determinations being carried out in the whole composition range and at seven temperatures in the range from 288.15 K to 318.15 K. In addition, the mixing enthalpies in the IL dilute region for (water + DCA IL) systems and the solid-liquid equilibria for (water + TFES IL) systems were experimentally determined. The dependences of activity coefficients on temperature and composition were correlated ( i ) separately with appropriate flexible equations and ( ii ) simultaneously with an extended NRTL model. Both correlation approaches provide adequate description of mixture energetics and, as documented by comparisons with other relevant data, allow extrapolations of activity coefficients to both higher and lower temperatures as well as good predictions of excess enthalpy. Furthermore, the volumetric and viscosity behavior of highly dilute solutions of the ILs was explored. The concentration dependences of the apparent volume and viscosity were fitted well by the respective classical Redlich-Meyer and Jones-Dole equations. The values of partial molar volumes at infinite dilution were found to perfectly obey the ion additivity and correlate well with the intrinsic volume of IL molecule. Thermodynamic behavior of studied systems was compared to each other and discussed with respect to molecular interactions and nanostructure as well as to how involved ions affect it. [ABSTRACT FROM AUTHOR]

Ionic Liquids (ILs) are task specific materials with tunable properties which may be applied as heat transfer fluids (HTFs) due to their characteristic properties including low vapour pressure, wide liquid range and high thermal stability. This study provides an evaluation of their potential as HTFs from both their physicochemical properties as well as an economic comparison with commonly used materials. The paper presents the thermophysical properties (density, isobaric heat capacity, ionic conductivity, viscosity, thermal stability by TGA, thermal conductivity) and their thermodynamic derivatives (isobaric thermal expansion coefficient, excess molar volume, excess molar heat capacity), as well as the Walden rule of ionicity for a range of hydrophobic ILs based on the trihexyl(tetradecyl)phosphonium, ([P 14,6,6,6 ] + ), cation. The ionic liquids studied are trihexyl(tetradecyl)phosphonium acetate ([AcO] − ), butanoate ([ButO] − ), hexanoate ([HexO] − ), octanoate ([OctO] − ), and decanoate ([DecO] − ), as well as their mixtures with water. It was shown that investigated systems are highly promising materials as HTFs, especially ILs + water mixtures, which may be the solution for many engineering issues. [ABSTRACT FROM AUTHOR]

This paper presents vapor-liquid equilibrium (VLE) data at 101.3 kPa for the ternary systems 1-propanol + water + 1-ethyl-3-methylimidazolium thiocyanate [emim][SCN] and 1-propanol + water + 1-butyl-3-methylimidazolium thiocyanate [bmim][SCN] and their constituents binary systems. The experimental data obtained were correlated using the NRTL, eNRTL and UNIQUAC models. It was found that the addition of these ionic liquids enhance the relative volatility of 1-propanol to water, and the separation ability follows the order of [emim][SCN] > [bmim][SCN]. The results obtained were compared with the VLE data of the system containing this azeotropic mixtures with different imidazolium-based ionic liquids reported in the literature. [ABSTRACT FROM AUTHOR]

This paper reports densities, ρ ijk and speeds of sound, u ijk data of ternary {1-butyl-2,3-dimethylimidazolium tetrafluoroborate (i) + 1-butyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium tetrafluoroborate (j) + cyclopentanone or cyclohexanone (k)} mixtures at temperatures 293.15 K to 308.15 K using a digital densimeter and speed of sound analyser. The observed ρ ijk and u ijk data have been employed to determine excess molar volumes, V ijk E and excess isentropic compressiblities, ( κ S E ) ijk respectively of the studied mixtures. The topology of the constituent molecules (Graph theory) of the binary ionic liquid mixtures has recently been utilized (Gupta et al., 2016) to predict their V E , κ S E , H E and C p E data. In the present studies, the topology of the components of the ternary mixtures (comprise of two ionic liquids and one organic solvent) has been employed (Graph theory) to obtain expressions for V ijk E and ( κ S E ) ijk data that describe well the measured V ijk E and ( κ S E ) ijk values. The observed V ijk E and ( κ S E ) ijk values have also been tested in terms of Prigogine-Flory-Patterson (PFP) theory. It has been observed that V ijk E and ( κ S E ) ijk values predicted by Graph theory are comparable with the experimental values. [ABSTRACT FROM AUTHOR]

Ternary liquid-liquid equilibria were experimentally determined for eight systems composed of an ionic liquid + n -hexane + an organic compound implicated in the racemic resolution of rac -2-pentanol ( rac -2-pentanol, vinyl butyrate, rac -2-pentyl butyrate or butyric acid) at a temperature of 303.15 K and pressure of 0.1 MPa. The following ionic liquids were used: 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [emim + ][NTf 2 − ], and 1-hexyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [hmim + ][NTf 2 − ]. The binodal curves and the tie line of the conjugate phases compositions were determined through measurement of the refractive index for the ionic liquid-rich phase and by using gas chromatography for the hexane-rich phase, enabling their potential to be assessed for selective extraction of organic compounds from a mixture of ionic liquid reaction media for the resolution of rac -2-pentanol. Liquid phase activity coefficients were calculated using the Non-Random Two-Liquid equation and the tie line theoretical data calculated from the model are in good agreement with the experimental data. As yet, the literature contains no data for the systems studied in this paper. [ABSTRACT FROM AUTHOR]

The focus of this paper is to study the liquid−liquid extraction process for the separation of toluene from alkane employing the ionic liquids N-butylpyridinium nitrate, [BPy][NO 3 ], and N-hexylpyridinium nitrate, [HPy][NO 3 ], as a new solvents. New experimental data for the ternary systems of {[BPy][NO 3 ] (1) + heptane, or octane, or decane (2) + toluene (3)} and {[HPy][NO 3 ] (1) + heptane, or octane, or decane (2) + toluene (3)} at T = 298.15 K and atmospheric pressure are reported. The Othmer-Tobias and Hand correlation are examined to check the reliability of the experimental LLE data. The toluene distribution ratios and selectivity were calculated form the experimental data. The selectivity values are higher than unity which indicates the ILs, [BPy][NO 3 ] and [HPy][NO 3 ], used in this work are potential solvents to separate toluene from alkane. Besides, the effect of the alkane chain length in the selectivity values was evaluated. In addition, the result of the NRTL thermodynamic modeling shows, the experimental data were satisfactorily correlated. [ABSTRACT FROM AUTHOR]

This paper reports experimental values of dynamic viscosity for four binary systems of 1-ethyl-3-methylimidazolium tetrafluoroborate, [Emim][BF4], with dimethyl sulfoxide (DMSO), acetonitrile (ACN), ethylene glycol (EG) and 1,4-dioxane over the temperature ranges from 293.15 K to 353.15 K at p = 0.1 MPa. All binary mixtures were completely miscible over the entire range of mole fraction, except the system with 1,4-dioxane. The viscosity results have been correlated by the one parameter Grunberg–Nissan and Fang and He equations and the two-parameter McAllister, Eyring-UNIQUAC, Eyring-NRTL and Eyring-Wilson models and the results were compared. Additionally, the viscosity deviations, Δ η , and the excess Gibbs energy of activation for viscous flow, G ∗ E , were calculated and fitted to the Redlich–Kister equation. The results show that all Δ η values are negative over the whole composition range and the G ∗ E values are positive, except for the system with EG. The results of the excess functions are discussed in terms of molecular interactions. [ABSTRACT FROM AUTHOR]

In this paper experimental densities and dynamic viscosities of pure 1-butyl-3-methylimidazolium dicyanamide ionic liquid, [bmim][DCA], and its binary liquid mixtures with γ-butyrolactone (GBL) are reported. All measurements were performed in the temperature range from (273.15 to 323.15) K at the pressure of 0.1 MPa for the various mixture compositions. From the experimental density the related volumetric parameters were calculated and fitted using Redlich–Kister’s polynomial equation. Obtained values are compared to those previously obtained for GBL mixtures with imidazolium and pyrrolidinium based ionic liquids containing bis(trifluoromethylsulfonyl)imide and dicyanamide anions. Other volumetric properties, such as isobaric thermal expansion coefficients, partial molar volumes and partial molar volumes at infinite dilution were also calculated, in order to obtain information about the interactions between GBL and the studied ionic liquid. From the viscosity results, the Angell strength parameter was calculated and found to be 3.75 indicating that [bmim][DCA] is a “fragile” liquid. [ABSTRACT FROM AUTHOR]

This paper reports the thermal, thermodynamic, thermophysical and surface properties of eight ionic liquids with fluorinated alkyl side chain lengths equal or greater than four carbon atoms. Melting and decomposition temperatures were determined together with experimental densities, surface tensions, refractive indices, dynamic viscosities and ionic conductivities in a temperature interval ranging from (293.15 to 353.15) K. The surface properties of these fluorinated ionic liquids were discussed and several thermodynamic functions, as well as critical temperatures, were estimated. Coefficients of isobaric thermal expansion, molecular volumes and free volume effects were calculated from experimental values of density and refractive index and compared with previous data. Finally, Walden plots were used to evaluate the ionicity of the investigated ionic liquids. [ABSTRACT FROM AUTHOR]

In this paper the volumetric behaviour of the ionic liquids 1-butyl-1-methylpyrrolidinium tetracyanoborate, 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, 1,3-dimethylimidazolium dimethylphosphate, 1-ethyl-3-methylimidazolium hexylsulfate, and trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate is reported. Density was measured over the temperature range (278.15 to 398.15) K up to 120 MPa by means of a high pressure densimeter based on the vibrating tube principle. Experimental values were correlated as a function of temperature and pressure by means of the Tammann–Tait equation obtaining standard deviations lower than 3 × 10 −4 g · cm −3 . From this correlation, isothermal compressibility and isobaric thermal expansivity are obtained by differentiation. Furthermore, two group contribution methods proposed by Gardas and Coutinho and by Jacquemin et al. are applied to these fluids to analyse their prediction abilities to determine densities, as well as an equation proposed by Kiselev et al. to obtain isothermal compressibility at 0.1 MPa. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive thermodynamic study of binary mixtures formed by 1-butyl-1-methylpyrrolidinium tetracyanoborate ionic liquid and hydrocarbons ( n -heptane, benzene, toluene, ethylbenzene), thiophene and alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol and 1-dodecanol). An impact of chemical structure of molecular compounds on their solubility in the ionic liquid and excess enthalpies of mixing is discussed. Furthermore, modelling of the measured properties by using perturbed-chain statistical associating fluid theory (PC-SAFT) is presented. The theory is applied in both correlative and semi-predictive mode involving temperature-dependent binary corrections fitted to infinite dilution activity coefficients. Solubility curves and excess enthalpies are captured by the model with a reasonable accuracy, when semi-predictive strategy is adopted. Moreover, (liquid + liquid) equilibrium phase diagram in ternary system composed of the investigated ionic liquid, thiophene and n -heptane is predicted with PC-SAFT and then the calculations are confronted with available experimental data. The results indicate that the approach proposed can be perceived as an interesting tool for reproducing the thermodynamic behaviour disclosed by such complex systems as those based on ionic liquids. [ABSTRACT FROM AUTHOR]

Three novel dicyanamide ionic liquids (ILs) [C n py][DCA] ( n = 3, 5, 6) and two [C n py][DCA] ( n = 2, 4) ( N -alkyl-pyridinium dicyanamide) were prepared and characterized by 1 H NMR spectroscopy, 13 C NMR spectroscopy, differential scanning calorimetry (DSC), High Performance Liquid Chromatography (HPLC) and FT-IR spectroscopy. The density, surface tension and refractive index were determined by the standard addition method (SAM) at T = 298.15 K. The experiment values of parachor for [C n py][DCA] ( n = 2, 3, 4, 5, 6) were calculated and the ionic parachor of anion, [DCA] − as a reference ion was obtained in terms of the extrathermodynamic assumption, and then the ionic parachor, P + , of all corresponding pyridinium cations, [C n py] + , were obtained. Using the values of P + of [C n py] + and [C n mim] + in our previous papers, the values of ionic parachor for 10 kinds of anions were obtained. By using the ionic parachor, the values of parachor for 47 ionic liquids were obtained, which are more closed to their experiment values than the values of parachor obtained by Rowley et al. The values of surface tension for 52 ionic liquids and the values of refractive index for 22 ionic liquids were predicted using the estimated values of parachor with their experimental expanded uncertainty at 0.95 confidence level of ±0.3 mJ · m −2 and ±0.0003, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a densimeter based on vibrating tube principle is used to determine experimentally the density of 1-butyl-2,3-dimethylimidazolium tris(pentafluoroethyl)trifluorophosphate and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide at temperatures between (278.15 and 398.15) K and at pressures up to 120 MPa. The apparatus was calibrated by using water, vacuum and bromobenzene. The Tammann–Tait equation of state was used to correlate ( p , T , ρ ) results with standard deviations around 2 · 10 −4 g · cm −3 . Other volumetric properties, such as isothermal compressibility and isobaric thermal expansivity, were obtained from this equation. For each ionic liquid, the α p isotherms present a crossing point within the experimental pressure range. Besides, the effect that the C2-methylation in the imidazolium cation provokes on density values is analyzed. The prediction ability of the group contribution methods of Gardas and Coutinho and Jacquemin et al. were tested with the experimental densities. [ABSTRACT FROM AUTHOR]

IoNanofluids have emerged as a possible alternative to current engineering fluids for heat transfer applications, namely in small volume heat exchangers and micro-channels. Thermal conductivity and density play a crucial role for the chemical plant design of green processes. Existing data are very scarce and inaccurate, mostly affected by impurities and the presence of water in the ionic liquids. In the present paper, we report new data on the thermal conductivity and density of 1- n -butyl-3-methyl-imidazolium dicyanamide ([C 4 mim][dca]), 1-ethyl-3-methyl-imidazolium dicyanamide ([C 2 mim][dca]) and 1-butyl-1-methyl-pyrrolidinium dicyanamide ([C 4 mpyr][dca]) at temperatures between (293 and 343) K at p = 0.1 MPa and IoNanofluids based on them with MWCNTs (multi-walled carbon nanotubes), in order to understand the effect of adding nanomaterials to a ionic liquid matrix and its modification of the heat transfer mechanism. Discussion about the effect of the cation, its side alkyl chain, head group and anion structure in the properties studied concluded that it is essential to understand better the mechanism of heat transfer in these systems, namely the role played by the interface ionic liquid (cation and anion)-nanoparticle, whatever molecular shape they have. Current theories used to calculate the thermal conductivity enhancement are insufficient to predict its value and variation with volume fraction of the nanomaterial. [ABSTRACT FROM AUTHOR]

Separation of aromatic and aliphatic hydrocarbons is a complex process in the petrochemical industry due to overlapping boiling points and azeotrope formation. In this paper, liquid extraction of aromatic compounds (toluene and ethylbenzene) from aliphatic compounds (hexane and cyclohexene) using ionic liquids (1-butyl-3-methylimidazolium methylsulfate, BMimMSO4, 1-propyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide, PMimNTf2, and 1-butyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide, BMimNTf2) as solvent was studied. (Liquid + liquid) equilibrium (ELL) data for the ternary systems {hexane (1) + ethylbenzene (2) + BMimMSO4, or BMimNTf2, or PMimNTf2 (3)}, {hexane (1) + toluene (2) + BMimMSO4 (3)} and {cyclohexene (1) + ethylbenzene (2) + BMimMSO4 (3)} were experimentally determined at T = 298.15 K and atmospheric pressure. Moreover, an analysis of the influence of the structure of each compound on the phase behavior was also carried out. The ability of the studied ILs to separate aromatic from aliphatic compounds was evaluated in terms of the solute distribution ratio, β, and the selectivity, S. The Non Random Two-Liquid (NRTL) and UNIversal QUAsiChemical (UNIQUAC) thermodynamic models were used to correlate the experimental LLE data. Furthermore, the COnductor-like Screening MOdel for Real Solvents (COSMO-RS) was applied to predict the (liquid + liquid) equilibrium. The suitability of this model to describe the phase behavior of the studied mixtures was evaluated comparing the experimental and calculated data. [ABSTRACT FROM AUTHOR]

Abstract: The use of ionic liquids as a media for dissolving DNA holds great promise for the development of new base materials in electrochemistry. This paper reports the systematic study of the effect of two nucleic acid bases, uracil and adenine, on the ionicity of 1-alkyl-3-methylimidazolium acetates achieved by monitoring several thermodynamic and transport properties. Density, dynamic viscosity, speed of sound, refractive index and ionic conductivity of 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium acetate were studied as a function of temperature at atmospheric pressure. The thermal expansion coefficients and molar volumes of these ionic liquids were calculated from the experimental density values. The various properties of the binary mixtures 1-ethyl-3-methylimidazolium acetate with uracil or adenine, namely, their ionic conductivity, density and viscosity in the temperature range 298K–343K were determined as a function of the nucleobase content. Walden plots were determined and used to clarify the role of the nucleobases in the ionic liquids ionicity. [Copyright &y& Elsevier]

Abstract: This paper presents new data on activity coefficients at infinite dilution, for 62 different solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, and water in the ionic liquid 4-(2-methoxyethyl)-4-methylmorpholinium trifluorotris(perfluoroethyl)phosphate, [COC2mMOR][FAP]. The data were determined by inverse gas chromatography at six temperatures from T =318.15K to T =368.15K. These values were compared with ionic liquid based on the same cation and bis(trifluoromethylsulfonyl)-amide anion, [COC2mMOR][NTf2]. Additionally the partial molar excess Gibbs free energies , enthalpies , and entropies at infinite dilution were calculated from the experimental values obtained over the temperatures range. The selectivities and capacities at infinite dilution for hexane/benzene, cyclohexane/benzene, and heptane/thiophene extraction problems were calculated from the to verify the possibility of investigated ionic liquid as an entrainer in liquid–liquid extraction and desulphurization of fuels. Obtained values were compared with literature data of other ionic liquids based on trifluorotris(perfluoroethyl)phosphate and bis(trifluoromethylsulfonyl)-amide anions and industrial solvents: NMP and sulfolane. Also the Abraham solvation parameter model was used for evaluation of the solvation characteristic of the ionic liquid. Linear free energy relationship (LFER) system constants as a function of temperature were calculated. [Copyright &y& Elsevier]

Abstract: Bahe–Varela (B–V) theory, based in the pseudo-lattice model, explains the thermodynamics of electrolyte solutions over the whole composition range. Thus, Bahe in 1972 extended the Debye–Huckel theory, developed for the most diluted electrolytes, to more concentrated solutions taking into account long range inter-ionic Coulombian forces. The introduction of long range interactions in the model generates naturally a pseudo-lattice arrangement of the ions in the concentrated liquid. As Bahe’s description fails at very concentrated solutions, in 1997 Varela and co-workers extended that pseudo-lattice theory by including the short range interactions with solvent molecules and other ions. In recent years, with the discovery of ionic liquids, B–V theory has attracted an increasing interest because these compounds can be seen as very concentrated electrolyte solutions (in fact they can be seen as “solutions” in the limit of no solvent!). Following this line, Turmine and co-workers in 2007 adapt the B–V theory to explain the volumetric properties of ionic liquid solutions up to saturation (i.e. the pure compound). They applied the equation extracted to fit the variation of the partial molar volume of three different aqueous solutions of IL with good results. In the present paper, we extend that analysis for systems formed by eight ILs and two solvents: water and ethanol. We have used density measurements for six aqueous mixtures recently published, two with 1-alkyl-3-methyl imidazolium tetrafluoroborate at T = 298K and four with 1-ethyl-3-methyl imidazolium alkyl sulphate at (288, 298, 308 and 318)K. Also we analyze seven mixtures with ethanol of the two same IL families and for the same temperatures than the aqueous systems. From the original data, we calculated the partial molar volume of the IL for all concentrations, being its variation lower than 2% for the aqueous systems (except that with EMIM-BF4, where it is 5%) and lower than 4% for those with ethanol. In spite of the simplicity of the Bahe–Varela equation, with only three fitting parameters, and of the three different forms of the partial molar volume versus concentration behaviour observed, the fitting quality of the B–V equation is excellent for all analyzed systems, which tends to confirm its universal validity. [Copyright &y& Elsevier]

Abstract: In this paper, the separation of toluene from the aliphatic hydrocarbons heptane and cyclohexane employing the ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [HMim][NTf2], 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, [HMim][TfO] and 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [BMim][TfO], as solvents was studied and discussed. Liquid–liquid equilibrium data for the ternary systems {heptane, or cyclohexane+toluene+[HMim][NTf2], or [HMim][TfO], or [BMim][TfO]} and {heptane+cyclohexane+[HMim][NTf2], or [HMim][TfO], or [BMim][TfO]} were measured at T =298.15K and atmospheric pressure. The degree of consistency of the tie-lines was tested using the Othmer–Tobias equation. The solute distribution ratio and selectivity, derived from the experimental tie-lines, were used to determine if these ionic liquids can be used as potential solvents on the extraction of toluene from aliphatic hydrocarbons; a comparison with literature data where sulfolane is used as solvent was also included. Finally, the experimental data were correlated with the NRTL and UNIQUAC thermodynamic models. [Copyright &y& Elsevier]

Abstract: In this paper, experimental densities and dynamic viscosities of 1-ethyl-3-methylimidazolium based ionic liquids (ILs) with the anions acetate and dicyanamide are presented in a wide temperature range (298.15 to 343.15K) at atmospheric pressure. Surface tension of these ILs was measured at T =298.15K. The effect of water and/or ethanol compositions on densities and dynamic viscosities of these ILs are studied in binary and ternary mixtures. A quadratic mixing rule was used to correlate binary and ternary liquid densities. The Eyring–Patel–Teja model, which is recommended for polar and aqueous systems, is used to correlate dynamic viscosity data over the whole range of compositions and temperatures in binary and ternary mixtures. Temperature-dependent interaction parameters are introduced here to account for the changes of viscosities with temperature showing good agreements with experimental data. [Copyright &y& Elsevier]

Abstract: In this paper, densities and speeds of sound for five binary systems {alcohol+1-butyl-3-methylimidazolium dicyanamide} were measured from T =(293.15 to 323.15)K and atmospheric pressure. From these experimental data, apparent molar volume and apparent molar isentropic compression have been calculated and fitted to a Redlich–Meyer type equation. This fit was also used to calculate the apparent molar volume and apparent molar isentropic compression at infinite dilution for the studied binary mixtures. Moreover, the osmotic and activity coefficients and vapor pressures of these binary mixtures were also determined at T =323.15K using the vapor pressure osmometry technique. The experimental osmotic coefficients were correlated using the Extended Pitzer model of Archer. The mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures were calculated from the parameters obtained in the correlation. [Copyright &y& Elsevier]

Abstract: In this paper, the interactions between cationic dyes and the ionic liquids (ILs) have been studied by 31P nuclear magnetic resonance (NMR), UV–Vis spectroscopy and conductometric measurements at different temperatures. It was shown that a decrease in the measured specific conductance of the (dye+IL) mixtures was caused by the formation of non-conducting or less conducting (dye+IL) associates. The associates were formed by 1:1 ratio of cation of the cationic dyes and anion of the ILs by using the 31P NMR and UV–Vis spectroscopy methods. The association constants were calculated by theoretical model based on the deviation from linear behavior, and the association constants were as high as 106 (L·mol−1)2. Thermodynamic results imply that the formation process of association was exothermic nature. It is expected that the associates reported here would have promising application as active materials for the preparation of ion-selective electrode used in the determination of ILs concentrations. [Copyright &y& Elsevier]

Abstract: In this paper, we demonstrate that it is possible to know the refractive index, nD , of every given mixture of 1-alkyl-3methyl imidazolium tetrafluoroborate with water and ethanol just from the knowledge of the refractive index and density of pure components. To do that, we measured nD for seven different mixtures in all range of existing concentrations and, independently, we deduce nD theoretically. Both sets of values differ less than a 0.2% on average. The theoretical deduction takes into account that these mixtures are quasi-ideal from the molar volume point of view, as recently published, and so density for any composition of the mixture can be obtained with a precision better than 0.5% from the pure compounds value. Now we simply apply Newton or Gladstone–Dale models, which relate the refractive index of a binary mixture with its density from the value of both pure components, without any fitting parameter. Both models are very similar in form and in the values they deduce (less than a 0.2% of difference), but while that of Newton performs slightly better for ethanol mixtures, the model of Gladstone–Dale gives some better results for aqueous mixtures. We think that these results can be extended to the majority of ionic liquid plus solvent systems. [Copyright &y& Elsevier]

Abstract: Efforts to make existing separation methods more efficient and eco-friendly may get a boost from the use of a relatively new class of compounds known as ionic liquids (ILs). The separation of azeotropic mixtures has conventionally been one of the most challenging tasks in industrial processes due to the fact that their separation by simple distillation is basically impossible. This paper provides a critical review of methods using ILs as azeotrope breakers. Three separation processes were addressed: liquid–liquid extraction, extractive distillation, and supported liquid membranes. We examine the azeotrope breaking potential of ILs and compare their performance to that of conventional solvents. A systematic analysis of the influence of the structure of ILs on their azeotrope breaking capacity contributes to the establishment of guidelines for selecting the most suitable ILs for the separation of specific azeotropic mixtures. [Copyright &y& Elsevier]

Abstract: In this paper, physical properties of a high purity sample of the ionic liquid 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [PMim][NTf2], and its binary mixtures with methanol, ethanol, 1-propanol, and 2-propanol were measured at atmospheric pressure. The temperature dependence of density, refractive index and speed of sound (293.15 to 343.15)K and dynamic viscosity (298.15 to 343.15)K were studied at atmospheric pressure by conventional techniques for the pure ionic liquid. For its mixtures with alcohols, density, speed of sound, and refractive index were measured at T =298.15K over the whole composition range. The thermal expansion coefficient of the [PMim][NTf2] was calculated from the experimental results using an empirical equation, and values of the excess molar volume, excess refractive index, and excess molar isentropic compressibility for the binary systems at the above mentioned temperature, were calculated and fitted to the Redlich–Kister equation. The heat capacity of the pure ionic liquid at T =298.15K was determined using DSC. [Copyright &y& Elsevier]

Abstract: This paper focuses on the study of the solubility behaviour of 1-hexyl-3-methylimidazolium tetracyanoborate [HMIM][TCB] and 1-butyl-3-methylimidazolium tetracyanoborate [BMIM][TCB] in combination with methylcyclohexane and toluene as representatives for non-aromatic and aromatic components. Binary and ternary (liquid+liquid) equilibrium data were collected at three different temperatures and at atmospheric pressure (0.1MPa). The experimental data were well-correlated with the NRTL and UNIQUAC thermodynamic models; however, the UNIQUAC model gave better predictions than the NRTL, with a root mean square error below 0.97%. The non-aromatic/aromatic selectivities of the ionic liquids make them suitable solvents to be used in extractive distillation processes. [Copyright &y& Elsevier]

Abstract: This paper reports the density, refraction index, and (vapor+liquid) equilibria (VLE) for binary systems {aldehyde+1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4])}: {propionaldehyde+[emim][EtSO4]} and {valeraldehyde+[emim][EtSO4]}. The uncertainties for the temperature, pressure, and compositions measurements for the phase equilibria are ±0.1K, ±0.01kPa and ±0.0004, respectively. A qualitative analysis of the variation of the properties with changes in solvent and temperature was performed. The Peng–Robinson equation of state (PR EoS), coupled with the Wong–Sandler mixing rule (WS), is used to describe the experimental data. To calculate activity coefficients we used three different models: NRTL, UNIQUAC, and COSMO-SAC. Since the predictive liquid activity coefficient model COSMO-SAC is used in the Wong–Sandler mixing rule, the resulting thermodynamic model is a completely predictive one. The prediction results for the density and for the (vapor+liquid) equilibria have a deviation lower than 2.3% and 1.6%, respectively. The (vapor+liquid) equilibria predictions show a good description for the propionaldehyde system and only a qualitative description for the valeraldehyde system. [Copyright &y& Elsevier]

Abstract: In this paper the extraction of toluene from cyclic hydrocarbons (cyclohexane, or methylcyclohexane, or cyclooctane, or cyclohexene) was analyzed by liquid extraction with 1-butyl-3-methylimidazolium methylsulfate ionic liquid, [BMim][MSO4], as solvent. The experimental (liquid+liquid) equilibrium (LLE) data were determined at T =298.15K and atmospheric pressure. Solubility curves were obtained by the cloud point method and tie-line compositions were determined by density measurement. An analysis of the influence of different cyclic hydrocarbons on the extraction was performed. The effectiveness of the extraction of toluene from cyclic hydrocarbons was evaluated by means of the solute distribution ratio and selectivity values. The degree of consistency of the experimental LLE data was ascertained using the Othmer–Tobias and Hand equations. The experimental data for the (liquid+liquid) equilibria of the ternary systems were correlated with the Non-Random Two-Liquid (NRTL) and UNIversal QUAsi-Chemical (UNIQUAC) thermodynamic models. [Copyright &y& Elsevier]

Abstract: In this paper, the feasibility of using 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid, [EMim][ESO4], as solvent for the extraction of toluene from aliphatic compounds (hexane, heptane, octane, or nonane) was analyzed. (Liquid+liquid) equilibrium (LLE) data for the ternary systems {alkane (1)+toluene (2)+[EMim][ESO4] (3)} were measured at T =298.15K and atmospheric pressure. Selectivity and solute distribution ratio were calculated from the experimental LLE data, and the obtained values were compared to those previously reported using other ionic liquids and sulfolane. The degree of consistency of the experimental LLE data was ascertained using the Othmer–Tobias equation. Finally, the experimental LLE data were satisfactorily correlated with NRTL and UNIQUAC models. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the ionic liquids 1,2-diethylpyridinium ethylsulfate, EEpyESO4; 1-methylpyridinium methylsulfate, MpyMSO4; 1,3-dimethylpyridinium methylsulfate, MMpyMSO4; and 2-ethyl-1-methylpyridinium methylsulfate, EMpyMSO4; were synthesized in our laboratory, and their experimental densities, speeds of sound, dynamic viscosities, and refractive indices were studied as a function of temperature at atmospheric pressure. Thermal expansion coefficient, molar volume, and molar refraction of these ionic liquids were calculated from the experimental density and refractive index values. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the separation of toluene from aliphatic hydrocarbons (heptane, or octane, or nonane) was analyzed by solvent extraction with 1-ethyl-3-methylpyridinium ethylsulfate ionic liquid, [EMpy][ESO4]. Liquid−liquid equilibrium (LLE) data for the ternary systems {heptane (1)+toluene (2)+[EMpy][ESO4] (3)}, {octane (1)+toluene (2)+[EMpy][ESO4] (3)}, and {nonane (1)+toluene (2)+[EMpy][ESO4] (3)} were obtained by measurements at T =298.15K and atmospheric pressure. The selectivity, % removal of aromatic, and solute distribution ratio, obtained from experimental equilibrium results, were used to determine the ability of [EMpy][ESO4] as a solvent. The degree of consistency of the experimental LLE values was ascertained using the Othmer–Tobias and Hand equations. The experimental results for the ternary systems were correlated with the NRTL model. Finally, the results obtained were compared with other ionic liquids and other solvents. [Copyright &y& Elsevier]

Abstract: The ionic liquid 1-ethyl-3-methylpyridinium ethylsulfate, [EMpy][ESO4], was studied for the separation of benzene from aliphatic hydrocarbons (octane or nonane) by solvent extraction through the determination of the (liquid+liquid) equilibrium (LLE) of the ternary systems: {octane (1)+benzene (2)+[EMpy][ESO4] (3)} and {nonane (1)+benzene (2)+[EMpy][ESO4] (3)} at T =(283.15 and 298.15)K and atmospheric pressure. Binodal curves were determined using the “cloud point” method, and tie-line compositions were obtained by density measurements. The values of selectivity and distribution coefficient, derived from the tie-line data, were used to decide if this ionic liquid can be used as potential solvent for the separation of benzene from aliphatic hydrocarbons using liquid extraction. These results were analyzed and compared to those previously reported for the systems {hexane+benzene+[EMpy][ESO4]} and {heptane+benzene+[EMpy][ESO4]}. The experimental results show that this ionic liquid is suitable for the extraction of benzene from mixtures containing octane and nonane. The consistency of tie-line data was ascertained by applying the Othmer–Tobias and Hand equations. The experimental results for the ternary systems were well correlated with the NRTL model. No literature data were found for the mixtures discussed in this paper. [Copyright &y& Elsevier]

Abstract: The density of seven {(0.0087, 0.0433, 0.1302, 0.2626, 0.4988, 0.7501, and 0.9102)mole fraction of [BMIM][BF4]} binary {methanol (1)+[BMIM][BF4] (2)} (1-butyl-3-methylimidazolium tetrafluoroborate) mixtures has been measured with a vibrating-tube densimeter. Measurements were performed at temperatures from (298 to 398)K and at pressures up to 40MPa. The total uncertainties of density, temperature, pressure, and concentration measurements was estimated to be less than 0.15kg·m−3, 15mK, 5kPa, and 10−4, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95% confidence level with a coverage factor of k =2. The effect of temperature, pressure, and concentration on the density and derived volumetric properties such as excess, apparent, and partial molar volumes was studied. The measured densities were used to develop a Tait-type equation of state for the mixture. The structural properties such as direct and total correlation function integrals and cluster size were calculated using the Krichevskii function concept and the equation of state for the mixture at infinite dilution. [Copyright &y& Elsevier]

Abstract: In the last years, new strict environmental regulations to reduce sulfur content in liquid fuels have been established. Thiophene derivates can be considered as the key substances to be separated from liquid fuel oils. This paper reports the ability of the ionic liquid 1-methyl-3-octylimidazolium tetrafluoroborate to act as solvent in the (liquid+liquid) extraction of thiophene from aliphatic hydrocarbons. Tie-line data have been determined for ternary systems containing the ionic liquid, thiophene, and some n-alkanes at T =298.15K. Extraction process has been analyzed by means of thiophene distribution ratio and selectivity. The solute distribution coefficient decreases and the selectivity increases as the chain length of n-alkane increases. The use of 1-methyl-3-octylimidazolium tetrafluoroborate as potential solvent for separation of thiophene from n-alkanes is feasible using the necessary quantity of solvent. A correlation of the equilibrium data reported here has also been made, using the NRTL activity coefficient model, in order to facilitate their use in simulation and design processes. [Copyright &y& Elsevier]

The liquid–liquid equilibrium data are presented for ternary mixtures {1-methyl-3-octyl-imidazoliumchloride (MeOctImCl) + benzene + an alkane} at T=298.2 K. The alkanes used were heptane, dodecane, and hexadecane. The compositions of the ternary mixtures on the coexistence curve and the conjugate solutions were evaluated using densities and a standard density calibration curve. The solvent MeOctImCl is an ionic liquid, which has a very low vapour pressure and a very high boiling temperature, and is therefore, a potentially environmentally friendly solvent. This ‘neoteric’ solvent is soluble in water and stable in air. There are very few data in the literature on ternary mixtures involving ionic liquids. The NRTL equation was used to correlate the experimental tie-lines. The NRTL equation gave good correlation of the tie-line data. There are no data in the literature for the mixtures discussed in this paper. The effectiveness of the extraction of benzene from an alkane by MeOctImCl is reported as a ratio of solubilities in the two phases. This quantity, known as the ‘selectivity’, was found to increase with increasing carbon number of the alkane. [Copyright &y& Elsevier]

• Phase behaviour and heat capacities of additional eight [C 1 C 2 Im] ionic liquids are studied calorimetrically. • Special attention is payed to drying of the samples and evaluation of the effect of impurities content. • Good agreement is observed between one of the previous adiabatic calorimetry studies of [C 1 C 2 Im][EtSO 4 and this work. • Yet undescribed complex polymorphic behaviour is reported for [C 1 C 2 Im][DCA] and [C 1 C 2 Im][MeSO 3. • Crystal structure of one polymorph of rarely crystallizing compound [C 1 C 2 Im][MeSO 3 is resolved. Ionic liquids are widely studied compounds with various potential applications, which are restricted by limited availability and understanding of their properties. Despite being commercially produced in a relatively high purity nowadays, the data on thermodynamic properties of ILs published in the most recent papers still keep large discrepancies. Phase behaviour, heat capacities, and crystal structures are studied in this work for additional eight common ionic liquids based on the 1-ethyl-3-methylimidazolium cation, [C 1 C 2 Im], coupled with simple organic or inorganic anions. Special attention is paid for drying of the samples, evaluation of the water content and its impact on the studied properties. All the samples were found to exhibit glass transitions, temperatures of which are determined with respect to the heating rate to simplify comparison with future works. The resulting melting temperatures, fusion enthalpies, and heat capacities are critically compared with the available data from the literature. Yet undescribed complex polymorphic behaviour is detected and resolved for methanesulfonate and dicyanamide salts, [C 1 C 2 Im][MeSO 3 and [C 1 C 2 Im][DCA], respectively. The X-ray powder diffraction analysis for samples melting above the room temperature was performed to support our results. A crystal structure for one of the polymorphs of [C 1 C 2 Im][MeSO 3 is reported for the first time. [ABSTRACT FROM AUTHOR]

• [C 2 2O1IM][SCN] was synthesized and confirmed. • The viscosities of binary mixtures were measured. • The Gibbs energy of activation for viscous flow of the relative viscosity for the mixture, Δ G ≠ r , was obtained. In this paper, a ether-group functionalized ionic liquid 1-(2-methoxyethyl)-3-ethylimidazolium thiocyanate [C 2 2O1IM][SCN] was synthesized and characterized by 1H NMR, 13C NMR, ESI mass spectrometry and elemental analysis, and the viscosities of [C 2 2O1IM][SCN] and of binary mixtures with monohydric alcohols (ethanol, 1-propanol, isopropanol and 1-butanol) were measured over the entire range of mole fraction in the temperature range from 288.15 K to 318.15 K and atmospheric pressure. The Arrhenius equation was used to describe the changing trends of viscosity with temperature. To investigate the internal interactions of the mixtures, the viscosity deviations, Δ η , and the Gibbs energy of activation for viscous flow of the relative viscosity for the mixture, Δ G ≠ r , were calculated based on the experimental viscosity, they were all negative values indicating that the hydrogen bond formation between ionic liquid and alcohol. In addition, the related entropies and enthalpies were also calculated and discussed. [ABSTRACT FROM AUTHOR]

• Volumetric properties of IL, [EMIM][ES] in four deep eutectic solvent were measured. • Redlich-Mayer equation was used to correlate of V φ and κ φ in infinite dilution. • The solute-solvent interactions are in order: ChCl/U > ChCl/EG > ChCl/Gly > ChCl/OX. Nowadays, green neteric solvents are replaced the conventional organic solvents. In this regard, deep eutectic solvents (DESs) have evolved as neoteric solvents similar to ionic liquids (ILs) with various applications in different fields. This paper reports the density, and speed of sound data of the ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM][ES] in the some DESs, choline chloride/urea, choline chloride/ethylene glycol, choline chloride/glycerol and choline chloride/oxalic acid in dilute region concentration of the IL at temperature ranges T = (298.15 to 318.15) K and at atmospheric pressure. On the basis of these data, the apparent molar volume V φ and apparent molar isentropic compressibility κ φ were calculated. From these quantities and with help of Redlich-Mayer equation, the standard partial molar volumes and partial molar isentropic compressibility were obtained. The structure making or breaking behaviour of the [EMIM][ES] in the DESs studied has been described with the help of standard partial molar isobaric expansions E φ 0 and Hepler constant. The obtained parameters show that solute-solvent interactions between the IL and the DES are stronger for the choline chloride/urea solutions than the other investigated DESs. Finally, the Pitzer model have been used to correlate the values of V φ and κ φ , which indicates the Pitzer model has a good compatibility than the other models. [ABSTRACT FROM AUTHOR]

• Phase behaviour and heat capacities of eight [C 1 C 2 Im] ionic liquids are studied calorimetrically. • Special attention is payed to drying of the samples and evaluation of the effect of water content. • Calorimetric results are critically compared with the literature data proving superior purity and lower uncertainty. • Crystal structures are determined for [C 1 C 2 Im][Me 2 PO 4 ], [C 1 C 2 Im][OTs], and two polymorphs of [C 1 C 2 Im][NO 3 ]. Ionic liquids start to leave the position of novel and astonishing compounds and become commercially available in a relatively high purity. Consequently, their thermodynamic properties should be described in a more thorough way than in the times of first pioneering studies revealing the importance of the water content. Available thermodynamic data, however, contradict this assumption keeping large discrepancies even among the data published in the most recent papers. Eight common ionic liquids based on the 1-ethyl-3-methylimidazolium cation, [C 1 C 2 Im], which are coupled with simple organic or inorganic anions are selected in this work and their phase behaviour, heat capacities, and crystal structures are studied. Special attention is paid to drying of the samples and evaluation of the effect of water content on the melting temperature. Resulting melting temperatures, fusion enthalpies, and heat capacities are compared to the available literature data. For the compounds, which melt above the room temperature, crystal structures were determined using the X-ray powder diffraction experiments to identify the studied crystalline phases. The thermodynamic and crystallographic data were used simultaneously to interpret the polymorphism of the investigated ionic liquids, where it occurred. Moreover, a crystal structure for the dimethyl phosphate salt [C 1 C 2 Im][Me 2 PO 4 ] is reported for the first time. [ABSTRACT FROM AUTHOR]