Prediction of liquid–liquid equilibrium for ternary systems containing ionic liquids with the tetrafluoroborate anion using ASOG (original) (raw)
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Fluid Phase Equilibria, 2015
A B S T R A C T Ionic liquids are neoteric, environmentally friendly solvents (since they do not produce emissions) composed of large organic cations and relatively small inorganic anions. They have favorable physical properties, such as negligible volatility and wide range of liquid existence. Liquid-liquid equilibrium (LLE) data for systems including ionic liquids, although essential for the design, optimization and operation of separation processes, are still scarce. However, some recent studies have presented ternary LLE data involving several ionic liquids and organic compounds such as alkanes, alkenes, alkanols, water, ethers and aromatics. In this work, the ASOG model for the activity coefficient is used to predict LLE data for 15 binary and 09 ternary systems at 101.3 kPa and several temperatures; all the systems are formed by ionic liquids including the tetrafluoroborate anion plus alkanes, alkanols, water, ethers, esters and aromatics. New group interaction parameters were determined using a modified Simplex method, minimizing a composition-based objective function of experimental data obtained from literature. The results are satisfactory, with rms deviations of about 3%.
The Journal of Chemical Thermodynamics, 2015
Ionic liquids are neoteric, environmentally friendly solvents (as they do not produce emissions) composed of large organic cations and relatively small inorganic anions. They have favorable physical properties, such as negligible volatility and a wide range of liquid existence. (Liquid + liquid) equilibrium (LLE) data for systems including ionic liquids, although essential for the design, optimization and operation of separation processes, remain scarce. However, some recent studies have presented ternary LLE data involving several ionic liquids and organic compounds such as alkanes, alkenes, alkanols, ethers and aromatics, as well as water. In this work, the ASOG model for the activity coefficient is used to predict LLE data for 25 binary and 07 ternary systems at 101.3 kPa and several temperatures; all the systems are formed by ionic liquids including the bis[(trifluoromethyl)sulfonyl]imide (NTf 2 ) anion plus alkanes, alkenes, cycloalkanes, alkanols, water, thiophene and aromatics. New group interaction parameters were determined using a modified Simplex method, minimizing a composition-based objective function of experimental data obtained from the literature. The results are satisfactory, with rms deviations of approximately 3%.
Fluid Phase Equilibria, 2009
Ionic liquids are neoteric, environmentally friendly solvents (since they do not produce emissions) composed of large organic cations and relatively small inorganic anions. They have favorable physical properties, such as negligible volatility and wide range of liquid existence. Moreover, many different cations and anions can be used to synthesize ionic liquid, so the properties can be designed by the use of selected combinations of anions and cations. Liquid–liquid equilibrium (LLE) data for systems including ionic liquids, although essential for the design and operation of separation processes, are still scarce. However, some recent studies have presented ternary LLE data involving several ionic liquids and organic compounds such as alkanes, alkenes, alkanols, water, ethers and aromatics. In this work, the ASOG model for the activity coefficient is used to predict the LLE for 11 binary and 17 ternary systems including the ionic liquid 1-alkyl-3-methylimidazolium hexafluorophosphate plus alkanes, alkenes, alkanols, ketones, carboxylic acids and aromatics. New group interaction parameters were determined by using a modified Simplex method, minimizing a composition-based objective function. The results are satisfactory, with rms deviations of about 4%.
Journal of Molecular Liquids, 2012
Ionic liquids (ILs) with their limitless combination of cations and anions can offer an optimal solvent for a specific purpose especially separation processes. Among ionic liquids, alkyl-sulfate derivatives are the most promising ILs to be applied in industrial processes. The present work investigates liquid-liquid equilibrium phase behavior of 12-ILs comprising sulfate-based anions. Computation of liquid-liquid equilibrium for 36 ternary systems is carried out using three local composition models, namely non-random two liquid (NRTL), non-random two liquid non-random factor (NRTL-NRF) and universal quasi chemical (UNIQUAC) activity coefficient models. All the interaction parameters of the three models are regressed using an optimization program based on Simplex method of Nelder and Mead. Comparison of the results is expressed by root mean square deviation (rmsd) between the experimental and calculated compositions. It is demonstrated that the NRTL-NRF model presents very good satisfactory results with rmsd values of about 1.05 so that this model is highly appropriate to calculate thermodynamic properties of ionic liquid solutions.
Fluid Phase Equilibria, 2004
Liquid-liquid equilibrium data are presented for mixtures of {1-hexyl-3-methylimidozolium(tetrafluoroborate or hexafluorophospate) + ethanol + (1-hexene or 1-heptene)} at T = 298.2 K. The data presented provides valuable insight into how variation of the anion of the environmentally friendly ionic liquid solvent can have a marked effect upon the separation power of ionic liquids. The sloping of the tie lines towards the ethanol vertex is observed for mixtures of {1-hexyl-3-methylimadozolium tetrafluoroborate + ethanol + (1-hexene or 1-heptene)}, whilst the reverse, i.e. sloping of the tie lines towards the ionic liquid vertex is observed for mixtures of {1-hexyl-3-methylimadozolium hexafluorophospate + ethanol + (1-hexene or 1-heptene)}. The tie line data have been correlated through the use of the NTRL model for statistical consistency. Selectivity values, derived from the tie line data, indicate that these two ionic liquids are suitable solvents for the liquid-liquid extraction of ethanol from olefins.
Predicting the ionicity of ionic liquids in binary mixtures based on solubility data: II
Fluid Phase Equilibria, 2023
"Ionic liquids (ILs) have been deeply investigated as possible substitutes for hazardous organic solvents, but their recently acknowledged ionicity, together with their generally high viscosity, has been hampering their further application. The ionicity (or degree of dissociation) of electrolytes affects properties such as viscosity, solubility and density, so it is of the utmost importance for the proper thermodynamic description of systems containing electrolytes. However, the experimental quantifications of this property are difficult to perform, which creates the need for more predictive approaches. In this work, the ionicity of 12 ionic liquids in binary mixtures composed of water, ethanol, 1-propanol or 1-butanol was predicted based on solubility data available in literature by the Pitzer-Debye-Hückel (PDH) equation combined with the UNIversal QUAsi-Chemical (UNIQUAC) model, which is often referred as PDH+UNIQUAC. The ionicity of the ionic liquids was modelled as function of mole composition for a total of 17 binary systems, comprising ILs of three chemical families: hexafluorophosphates, tetrafluoroborates, and bis(trifluoromethylsulfonyl)imides, continuing a previous work. This novel methodology provided a useful tool to estimate the ionicity of ionic liquids containing imidazolium cations without undergoing long experimental determinations, which could be applied in the design of separation processes."
Journal of Chemical & Engineering Data, 2003
Activity coefficients at infinite dilution, γ ∞ i , have been determined for polar and non-polar organic solutes in the high molecular weight ionic liquid, trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl) trifluorophosphate at T = 308.15, 318.15 and 328.15 K. The experimental activity coefficient data presented are the first to be reported for the phosphonium-based ionic liquid. For the measurement of γ ∞ i , the technique of steady-state gas-liquid chromatography has been employed. The organic solutes that were investigated were normal alkanes (pentane, hexane, heptane and octane), alkenes (1-hexene, 1-heptene and 1-octene), alkynes (1-hexyne, 1-heptyne and 1-octyne), cycloalkanes (cyclopentane, cyclohexane and cycloheptane), alcohols (methanol, ethanol and propanol) and benzene. The partial molar excess enthalpies at infinite dilution, H E, ∞ i , were also determined for the solutes from the temperature dependency of the γ ∞ i values. The γ ∞ i data obtained for trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl) trifluorophosphate in this investigation have been compared to that obtained for other ionic liquids available in literature and the potential for the use of ionic liquids as solvents in industrial solvent-enhanced separation processes such as extractive distillation has been discussed.
Predicting the ionicity of ionic liquids in binary mixtures based on solubility data
Fluid Phase Equilibria, 2023
"Ionic liquids (ILs) are ionic compounds which are liquid at room temperature and pressure, and can be applied in many fields, such as industrial synthesis, catalysis, electrochemistry, and liquid-liquid separations. To enhance the description of mixtures containing ILs and, consequently, to allow a more rigorous evaluation of the feasibility of chemical processes, it is important to study properties such as the ionicity (α) of ionic liquids, i.e., the fraction of dissociated molecules. However, experimental determinations of ionicity (also known as dissociation degree or dissociation extent) are time-consuming and require the handling of expensive equipment, so the prediction of this property as a function of the system's composition using thermodynamic modelling is of great relevance. For that purpose, the UNIversal QUAsi-Chemical (UNIQUAC) model was combined with the Pitzer-Debye-Hückel (PDH) equation, which is often referred as PDH+UNIQUAC, and it was used to predict the ionicity of ILs in binary mixtures based on liquid-liquid equilibria (LLE) data. The results were compared with the available experimental data from literature and low deviations were observed, validating thereafter the developed approach. In total, the IL ionicity was predicted, as function of composition, for fourteen ionic liquid / solvent (water or 1-butanol) binary systems. Further, a sensitivity analysis was performed to evaluate the influence of the LLE uncertainties on ionicity (α), and it was concluded that α was not significantly affected by small deviations, for which the methodology proposed in this work was considered robust. The prediction of IL ionicity with composition using PDH+UNIQUAC thermodynamic modelling was considered a breakthrough, since very accurate results were achieved without the need of undergoing complex experiments."
Experiments and Modelling of Systems with Ionic Liquids
This paper presents the high-pressure phase behavior of the binary system 1-octyl-3- methylimidazolium tetrafluoroborate ((omim)(BF4)) + carbon dioxide (CO2) in the mole fraction range 0.1< xCO2< 0.75, and in the pressure and temperature range of 0.1-100 MPa and 303-363 K, respectively. High solubilities of CO2 for xCO2< 0.6 were established at relatively low pressure, while for xCO2 > 0.6 a dramatic increase of the equilibrium pressure was observed. The Group Contribution Equation of State (GC-EOS) was applied to predict the phase behavior of binary systems of ionic liquids of the homologous family like 1-alkyl-3-methylimidazolium hexafluorophosphate and tetrafluoroborate with CO2. Pure group parameters for the new ionic liquid functional group (-mim)(BF4) and interaction parameters between these groups and the paraffin (CH3, CH2) and CO2 groups were estimated. The GC-EOS was applied to predict the high-pressure phase equilibria in binary mixtures of the ionic liquids (...