Separation of toluene from cyclic hydrocarbons using 1-butyl-3-methylimidazolium methylsulfate ionic liquid at T = 298.15 K and atmospheric pressure

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 = 298.15 K 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.     

Densities and volumetric properties of binary mixtures of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate with benzaldehyde at T = (298.15 to 313.15) K

The densities of the binary mixtures formed by 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF₄] with aromatic compound (benzaldehyde) have been determined over the full range of compositions at the temperature range from (298.15 to 313.15) K and at atmospheric pressure using a vibrating-tube densimeter (DMA4500). Excess molar volumes $(V_{\text{m}}^{\text{E}})$ have been obtained from these experimental results, and been fitted by the fourth-order Redlich–Kister equation. In addition, partial molar volumes, apparent molar volumes, and partial molar volumes at infinite dilution have been calculated for each component. Our results show $V_{\text{m}}^{\text{E}}$ decreases slightly when temperature increases in the systems studied. The results have been interpreted in terms of ion–dipole interactions and structural factors of the ionic liquid and these organic molecular liquids.     

Excess thermodynamic properties of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate and N-octyl-2-pyrrolidone from T = (298.15 to 323.15) K at atmospheric pressure

Density (ρ), refractive index (n_D) and speed of sound (u) values are measured for the binary mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and N-octyl-2-pyrrolidone over the entire range of mole fraction at temperatures from T = (298.15 to 323.15) K under atmospheric pressure. Using the basic experimental data, various acoustic and excess thermodynamic parameters are calculated and are discussed in terms of molecular interactions between the present investigated binary system. The excess values are fitted to Redlich–Kister polynomial equation to estimate the binary coefficients and standard deviation between the experimental and calculated values. Further, the molecular interactions in the binary mixture system are analysed using the experimental FT-IR spectrum recorded at room temperature.     

Separation of toluene from alkanes using 1-ethyl-3-methylpyridinium ethylsulfate ionic liquid at T = 298.15 K and atmospheric pressure

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 = 298.15 K 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.     

Monte Carlo simulations of gas solubility in the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate

The Henry's constants of water, carbon dioxide, ethane, ethene, methane, oxygen, and nitrogen are computed in the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) using test particle insertion and expanded ensemble Monte Carlo methods. The partial molar enthalpy and partial molar entropy of solvation are also computed for water, carbon dioxide, and oxygen. The results from the simulations are compared against experimental data from the literature. In addition, the accuracy and precision of the two methods in determining the Henry's constant are examined. Local organization of the ionic liquid around a solute molecule is analyzed, and the interactions responsible for the experimentally observed solubility trends are identified.     

Diffusion coefficients of nickel chloride in aqueous solutions of lactose at T = 298.15 K and T = 310.15 K

Binary mutual diffusion coefficients (interdiffusion coefficients) of nickel chloride in water at T = 298.15 K and T = 310.15 K, and at concentrations between (0.000 and 0.100) mol · dm^?3, using a Taylor dispersion method have been measured. These data are discussed on the basis of the Onsager–Fuoss and Pikal models. The equivalent conductance at infinitesimal concentration of the nickel ion in these solutions at T = 310.15 K has been estimated using these results. Through the same technique, ternary mutual diffusion coefficients (D₁₁, D₂₂, D₁₂, and D₂₁) for aqueous solutions containing NiCl₂ and lactose, at T = 298.15 K and T = 310.15 K, and at different carrier concentrations were also measured. These data permit us to have a better understanding of the structure of these systems and the thermodynamic behaviour of NiCl₂ in different media.     

Effect of tri-potassium phosphate on volumetric,acoustic, and transport behaviour of aqueous solutions of 1-ethyl-3-methylimidazolium bromide at T = (298.15 to 318.15) K

Density, sound velocity, and viscosity of 1-ethyl-3-methylimidazolium bromide, [Emim][Br], in aqueous solutions of tri-potassium phosphate with salt weight fractions (w_s = 0.00, 0.10, 0.15, and 0.20) have been measured as a function of concentration of [Emim][Br] at atmospheric pressure and T = (298.15, 303.15, 308.15, 313.15, and 318.15) K. The apparent molar volume, isentropic compressibility, apparent isentropic compressibility, and relative viscosity values have been evaluated from the experimental data. The partial molar volume and isentropic compressibility at infinite dilution, and viscosity B-coefficient obtained from these data have been used to calculate the corresponding transfer parameters for the studied IL from water to the aqueous tri-potassium phosphate solutions. Also, an empirical equation was satisfactorily used to correlate the experimental viscosity data.     

Diffusion of sodium alginate in aqueous solutions at T = 298.15 K

Taylor dispersion technique was used for measuring mutual diffusion coefficients of sodium alginate aqueous solutions at T = 298.15 K, by using as carrier stream solution both pure water and solutions of this polyelectrolyte at a slightly different concentration. The limiting values found at infinitesimal ionic strength, D⁰, were determined by extrapolating to c → 0. These studies were complemented by molecular mechanics calculations. From the experimental data, it was possible to estimate both the limiting conductivity and the tracer diffusion coefficient values for the alginate anion, and the hydrodynamic radius of the sodium alginate (NaC₆H₇O₆), as well as to discuss the influence of the kinetic, thermodynamic and viscosity factors on the diffusion of sodium alginate in aqueous solutions at finite concentrations. Thus, the aim of our innovative research is to contribute to a better understanding of the structure and the thermodynamic behavior of these polymeric systems in solution and supplying the scientific and technological communities with data on these important parameters in solution transport processes.     

Non-ideal behaviour of imidazolium based room temperature ionic liquids in ethylene glycol at T = (298.15 to 318.15) K

Non-ideal behaviour of the room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF₄]; 1-octyl-3-methylimidazolium tetrafluoroborate [omim][BF₄] and 1-butyl-3-methylimidazolium octylsulfate [bmim][C₈OSO₃] in ethylene glycol [HOCH₂CH₂OH] (EG) have been investigated over the whole composition range at T = (298.15 to 318.15) K. For the purpose, volumetric properties such as excess molar volumes, $V_m^E$, apparent molar volumes, $V_{?\text{,}i}$, partial molar volumes, ${\overline{V}}_{m\text{,}i}$, excess partial molar volumes, ${\overline{V}}_{m\text{,}i}^E$, and their limiting values at infinite dilution, $V_{?\text{,}i}^{\infty }$, ${\overline{V}}_{m\text{,}i}^{\infty }$, and ${\overline{V}}_{m\text{,}i}^{E\text{,}\infty }$ respectively have been calculated from the experimental density measurements. The $V_m^E$ results have been analyzed using the Prigogine–Flory–Patterson (PFP) theory. PFP theory has satisfactorily explained the volumetric behaviour of the binary mixtures. Refractive index measurements at 298.15 K have been used to calculate the deviations in refractive indices ${\Delta }_{?}n$ and the deviation of molar refraction Δ_xR from their respective ideal values. Refractive index results have been correlated with volumetric results, and have been interpreted in terms of molecular interactions. Excess properties are fitted to the Redlich–Kister polynomial equation to obtain the binary coefficients and the standard errors.     

Investigation of 1-(2-carboxyethyl)-3-methylimidazolium chloride[HOOCEMIM][Cl] ionic liquid effect on water activity and solubility of l-serine at T = 298.15 K

Water activity measurements by the isopiestic method have been carried out on the aqueous ternary system of {l-serine + 1-(2-carboxyethyl)-3-methylimidazolium chloride[HOOCEMIM][Cl]} ionic liquid and the aqueous binary system of IL at T = 298.15 K and atmospheric pressure. The data obtained were used to calculate the vapor pressure and osmotic coefficient of solution as a function of concentration. The experimental results for the activity of water were accurately correlated with segment-based local composition models of modified NRTL and UNIQUAC. The fitting quality of the above models has been favorably compared with the NRTL and Wilson models. From these data, the corresponding activity coefficients have been calculated. For the same system, the solubility of the l-serine at various [HOOCEMIM][Cl] ionic liquid concentrations was measured at T = 298.15 K using the gravimetric method. A chemical model was employed to describe the dissociation equilibria of all amino acid species with hydrogen ions in water. Moreover, for l-serine, the chemical model indicated that the formation of cations is insignificant in the [HOOCEMIM][Cl] solution. Also the above local composition models were used to predict the solubility of l-serine in aqueous IL solutions. To provide information regarding (solute + solute) interactions, transfer Gibbs free energies (ΔG_tr) of amino acid from water to aqueous IL solutions have been determined.     

Heat of solution of polyhalite and its analogues at T = 298.15 K

Calorimetric measurements have been performed to determine the heat of dissolution of polyhalite K₂SO₄ · MgSO₄ · 2CaSO₄ · 2H₂O and its analogues K₂SO₄ · MSO₄ · 2CaSO₄ · 2H₂O (M = Mn, Co, Ni, Cu, and Zn) at T = 298.15 K. The dissolution experiments were carried out in NaClO₄ solution with varying concentrations (0.5 to 2.0) mol kg^?1. All polyhalites dissolve exothermically. Exothermicity increases with concentration of NaClO₄. An extrapolation to infinite dilution was done using the SIT model.Within the limits of experimental uncertainty, the enthalpies of dissolution for the triple salts K₂MgCa₂(SO₄)₄ · 2H₂O with M = Mg, Mn, Ni, and Zn coincide. The value for the cobalt salt is noticeably less exothermic. Dissolution enthalpy of leightonite K₂CuCa₂(SO₄)₄ · 2H₂O, which does not crystallize in the polyhalite structure, deviates considerably within the series.     

Densities of aqueous solutions containing model compounds of amino acids and ionic salts at T = 298.15 K

Densities of amino acids in aqueous and in aqueous electrolyte solutions have been measured by a high precision vibrating tube digital densitometer at T = 298.15 K under atmospheric pressure. The investigated systems contained amino acids of zwitterionic glycine peptides: glycine (Gly), diglycine (Gly₂), triglycine (Gly₃), and tetraglycine (Gly₄) and cyclic glycylglycine (c(GG)) with electrolytes of potassium chloride (KCl), potassium bromide (KBr) and potassium acetate (KAc). In this series of measurements, the aqueous samples were prepared with various concentrations of the amino acids, up to saturated conditions, and over salt concentrations from 1 to 4 M. The density increments resulting from the addition of the different model compounds of amino acids and the ionic salts were investigated, respectively. An empirical linear combination equation with an augmented term to account the interactions between amino acid and ionic salt was used to quantitatively correlate the experimental densities over the entire concentration ranges.     

Volumetric and isentropic compressibility behaviour of aqueous solutions of (polyvinylpyrrolidone + sodium citrate) at T = (283.15 to 308.15) K

The apparent specific volumes and isentropic compressibilities have been determined for polyvinylpyrrolidone in aqueous solutions of sodium citrate by density and sound velocity measurements at T = (283.15 to 308.15) K at atmospheric pressure. The results show a positive transfer volume of PVP from an aqueous solution to an aqueous sodium citrate solution. For low concentrations of PVP, the apparent specific volumes of PVP in water increased along with an increase in the polymer mass fraction, while in aqueous sodium citrate solutions decreased along with an increase in the polymer mass fraction. For high concentrations of PVP, the apparent specific volumes of PVP in water and in aqueous sodium citrate solutions were independent of the polymer mass fraction. The apparent specific isentropic compressibility of PVP is negative at T = (283.15 and 288.15) K, which imply that the water molecules around the PVP molecules are less compressible than the water molecules in the bulk solutions. The positive values of apparent specific isentropic compressibility at T = (298.15, 303.15, and 308.15) K imply that the water molecules around the PVP molecules are more compressible than the water molecules in the bulk solutions. Finally, it was found that the apparent specific isentropic compressibility of PVP increases as the concentration of sodium citrate increases.