Marek Królikowski

Phase equilibria and modeling of ammonium ionic liquid, C2NTf2, solutions.

Novel quaternary ammonium ionic liquid, ethyl(2-hydroxyethyl)dimethylammonium bis(trifluomethylsulfonyl)imide (C2NTf2), has been prepared from N,N-dimethylethanolamine as a substrate. The paper includes a specific basic characterization of the synthesized compound by NMR and the basic thermophysical properties: the melting point, enthalpy of fusion, enthalpy of solid-solid phase transition, glass transition determined by the differential scanning calorimetry (DSC), temperature of decomposition, and water content. The density of the new compound was measured. The solid-liquid or liquid-liquid phase equilibria of binary mixtures containing {C2NTf2+water or an alcohol (propan-1-ol, butan-1-ol, hexan-1-ol, octan-1-ol, decan-1-ol), aromatic hydrocarbons (benzene, toluene), aliphatic hydrocarbons (n-hexane, n-octane), dimethylsulfoxide (DMSO), or tetrahydrofuran (THF)} have been measured by a dynamic method in a wide range of temperatures from 230 to 430 K. These data were correlated by means of the nonrandom two-liquid (NRTL) equation utilizing temperature-dependent parameters derived from the solid-liquid or liquid-liquid equilibrium. From the solubility results, the negative value of the partition coefficient of ionic liquid in binary system octan-1-ol/water (log P) at 298.15 K has been calculated.

Excess Enthalpies of Mixing of Piperidinium Ionic Liquids with Short-Chain Alcohols: Measurements and PC-SAFT Modeling

This work is a continuation of our systematic study on thermodynamic properties of 1-n-alkyl-1-methylpiperdinium bis[(trifluoromethyl)sulfonyl]imides homologous series of ionic liquids ([CnC1Pip][NTf2]). Excess enthalpies of mixing (H(E)) of four binary systems containing two ionic liquids, namely [C4C1Pip][NTf2] and [C6C1Pip][NTf2], and two short-chain alcohols, namely ethanol and 1-propanol, were measured by isothermal titration calorimetry. Alcohol-to-ionic liquid and ionic liquid-to-alcohol titration experiments were carried out at temperature T = 298.15 K and atmospheric pressure. The experimental data were modeled in terms of perturbed-chain statistical associating fluid theory (PC-SAFT). Wolbach-Sandler combining rules were adopted in order to account for ionic liquid-alcohol cross-association. The model was applied in a conventional manner (i.e., without any binary corrections) as well as in a novel predictive mode developed previously by our group [Paduszyński, K.; Domańska, U. J. Phys. Chem. B 2012, 116, 5002-5018; Domańska et al. J. Phys. Chem. B 2012, 116, 8191-8200]. The latter approach employs temperature-dependent binary correction fitted to experimental limiting activity coefficient of alcohol in ionic liquid.

Perturbed-Chain SAFT as a Versatile Tool for Thermodynamic Modeling of Binary Mixtures Containing Isoquinolinium Ionic Liquids

This contribution reports a recapitulation of our experimental and modeling study on thermodynamic behavior of binary systems containing N-alkylisoquinolinium ionic liquids (ILs) based on bis(trifluoromethylsulfonyl)imide anion, [CniQuin][NTf2] (n = 4,6,8). In particular, we report isothermal vapor-liquid equilibrium (VLE) phase diagrams and molar excess enthalpies of mixing (H(E)) for binary mixtures of [C8iQuin][NTf2] IL with various organic solutes including benzene, toluene, thiophene, pyridine, and butan-1-ol. The measured VLE data represented simple homozeotropic behavior with either negative or positive deviations from ideality, depending on polarity of the solute, temperature, and mole fraction of IL. In turn, the obtained data on H(E) were negative and positive for the mixtures containing aromatic hydrocarbons or thiophene and butan-1-ol, respectively, in the whole range of ILs concentration. All of the measured and some previously published data regarding phase behavior of [C8iQuin][NTf2] IL were analyzed and successfully described in terms of perturbed-chain statistical associating fluid theory (PC-SAFT). The methodology used in this work was described by us previously. In general, the proposed modeling results in VLE diagrams, which are in excellent agreement with experimental data. In the case of H(E), the results obtained are good as well but not so satisfactory such as those for VLE. Nevertheless, they seem to be very promising if one take into account the simplicity of the utilized molecular model against significant complexity of IL-based systems. Thus, we concluded that PC-SAFT equation of state can be viewed as a powerful and robust tool for modeling of systems involving ILs.

Excess enthalpies of mixing, effect of temperature and composition on the density, and viscosity and thermodynamic properties of binary systems of {ammonium-based ionic liquid + alkanediol}.

In the present work the excess enthalpies of butyltrimethylammonium bis(trifluoromethyl-sulfonyl)imide, [N1114][NTf2], with 1,2-propanediol, or 1,2-butanediol, or 2,3-butanediol have been measured at T = 298.15 K. Additionally, the density, ρ, and dynamic viscosity, η, for binary solutions containing ionic liquids (ILs) and alkanedioles, {butyltrimethylammonium bis(trifluoromethyl-sulfonyl)imide, [N1114][NTf2], + 1,2-propanediol, 1,2-butanediol, 2,3-butanediol} and {(2-hydroxyethyl)trimethylammonium bis(trifluoro-methylsulfonyl)imide, [N1112OH][NTf2], + 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol}, at wide temperature and composition ranges at ambient pressure have been investigated. From experimental values of the density, ρ, and dynamic viscosity, η, the excess molar volumes, V(E), and dynamic viscosity deviations, Δη, were calculated and correlated using the Redlich-Kister polynomial equation. The temperature dependence of density and viscosity for the tested binary systems was described by an empirical second-order polynomial and by the Vogel-Fucher-Tammann equation, respectively. The variation of density and viscosity as a function of composition has been described by the polynomial correlations. Comparison of the experimental results for the binary mixtures tested in this work allows us to determine the influence of alkanediol carbon chain length, the position of the hydroxyl group in the alcohol, and the influence of the structure of the cation of the ionic liquid on the presented properties.

Thermodynamic Study of Binary Mixtures of 1-Butyl-1-methylpyrrolidinium Dicyanamide Ionic Liquid with Molecular Solvents: New Experimental Data and Modeling with PC-SAFT Equation of State

This work is concerned with thermodynamic properties of binary mixtures composed of 1-butyl-1-methylpyrrolidinium dicyanamide ionic liquid (IL) and the following molecular solvents: n-heptane, benzene, toluene, ethylbenzene, thiophene, 1-butanol, 1-hexanol, and 1-octanol. This is the very first time when experimental data on liquid-liquid equilibrium (LLE) phase diagrams and excess enthalpies of mixing (H(E)) for these systems are reported. An impact of the molecular solvent structure on LLE and H(E) is discussed. Furthermore, modeling of the properties under study is presented by using perturbed-chain statistical associating fluid theory (PC-SAFT). The equation of state is used in purely predictive and semipredictive mode. The latter one involves temperature-dependent binary corrections to combining rules employed in the PC-SAFT model determined on the basis of infinite dilution activity coefficients. The results shown indicate that such an approach can serve as an interesting modern thermodynamic tool for representation of thermodynamic data for complex ILs-based systems.

Phase equilibria and modeling of pyridinium-based ionic liquid solutions.

The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide ([BM(4)Py][NTf(2)]) with water, an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), an aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), an alkane (n-hexane, n-heptane, n-octane), or cyclohexane have been measured at atmospheric pressure using a dynamic method. This work includes the characterization of the synthesized compound by water content and also by differential scanning calorimetry. Phase diagrams for the binary systems of [BM(4)Py][NTf(2)] with all solvents reveal eutectic systems with regards to (solid-liquid) phase equilibria and show immiscibility in the liquid phase region with an upper critical solution temperature (UCST) in most of the mixtures. The phase equilibria (solid, or liquid-liquid) for the binary systems containing aliphatic hydrocarbons reported here exhibit the lowest solubility and the highest immiscibility gap, a trend which has been observed for all ILs. The reduction of experimental data has been carried out using the nonrandom two-liquid (NRTL) correlation equation. The phase diagrams reported here have been compared with analogous phase diagrams reported previously for systems containing the IL N-butyl-4-methylpyridinium tosylate and other pyridinium-based ILs. The influence of the anion of the IL on the phase behavior has been discussed.

Thermodynamics and activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid N-hexyl-3-methylpyridinium tosylate.

The activity coefficients at infinite dilution, γ13(∞), for 44 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, tetrahydrofuran, ethers, and ketones in the ionic liquid (IL) N-hexyl-3-methylpyridinium tosylate (p-toluenesulfonate), [HM3Py][TOS], were determined by gas-liquid chromatography at temperatures from 338.15 to 368.15 K. The densities of [HM3Py][TOS] as a function of temperature have been measured at temperatures higher than the melting temperature and were extrapolated to T = 298.15 K. The gas-liquid partition coefficients, K(L) were calculated for all solutes. The partial molar excess Gibbs energies ΔG1(E,∞), enthalpies ΔH1(E,∞), and entropies ΔS1(E,∞) at infinite dilution were calculated from the experimental γ13(∞) values obtained over the temperature range. The selectivities for different separation problems including n-heptane/benzene, cyclohexane/benzene, and n-heptane/thiophene were calculated from γ13(∞) and compared to literature values for tosylate-based ILs, or hexyl-substituted cations of ILs, or pyridynium-based IL, or N-methyl-2-pyrrolidinone (NMP), and sulfolane.

Heat Capacity, Excess Molar Volumes and Viscosity Deviation of Binary Systems of N-octylisoquinolinium bis{(trifluoromethyl)sulfonyl}imide Ionic Liquid

Abstract Heat capacities were determined for two binary systems {N-octylisoquinolinium bis{(trifluoromethyl)sulfonyl} imide, ([C8iQuin][NTf2]) + benzene, or butan-1-ol} from (288.15 to 388.15) K. Density and viscosity were determined for four binary mixtures containing {[C8iQuin][NTf2]) + benzene, or toluene, or thiophene or pyridine} at six temperatures (298.15, 308.15, 318.15, 328.15, 338.15 and 348.15) K, ambient pressure, and covering the entire composition range. The influence of temperature and composition was discussed. As usually the heat capacity increases with an increase of the ionic liquid concentration. The molar heat capacities, densities and viscosities were correlated with suitable equations. The excess molar heat capacities, Δ Cp, the excess molar volumes, VmE and dynamic viscosity deviations, Δη were described by the Redlich–Kister polynomial expansion. The Δ Cp was negative for benzene and S-shaped for butan-1-ol, the VmE and Δη were low and negative. From the experimental values, the volume expansivity and the excess volume expansivity was calculated. The obtained results indicate that ionic liquid interactions with aromatic hydrocarbons are strong dependent on the packing effects and π–π interactions.