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    Phase equilibria measurements of ternary mixtures (sulfolane + a carboxylic acid + pentane) at 303.15 K
    (Elsevier, 2015) Xhakaza, Nokukhanya Mavis; Bahadur, Indra; Redhi, Gan G.; Ebenso, Eno E.
    The Liquid–liquid equilibrium (LLE) data for the mixtures of {sulfolane (1) + a carboxylic acid (2) + pentane (3)} at 303.15 K are reported, where a carboxylic acid refers to acetic acid, propanoic acid, butanoic acid, 2-methylpropanoic acid, pentanoic acid and 3-methylbutanoic acid. The shape of the binodal curves show that the solubility of pentane in (sulfolane + a carboxylic acid) is very much dependent on the carbon number and the type of carboxylic acid. The area of the two phase heterogeneous region for the carboxylic mixtures decreases in the order of acetic acid > propanoic acid > 2-methylpropanoic acid ∼ butanoic acid > pentanoic acid ∼ 3-methylbutanoic acid. Three parameter equations have been fitted to the binodal curve data. The NRTL and UNIQUAC models were used to correlate the experimental data. The NRTL model fitted the experimental data better than the UNIQUAC model with the average mean square deviation of 0.072 mole fraction as compared to 0.359 mole fraction for UNIQUAC model.
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    Influence of the alkyl group on thermophysical properties of carboxylic acids in 1-butyl-3-methylimidazolium thiocyanate ionic liquid at various temperatures
    (Elsevier, 2015) Redhi, Gan G.; Ebenso, Eno E.; Singh, Suren; Bahadur, Indra; Ramjugernath, Deresh
    In the present study, influence of the alkyl group and temperature on the interactions between the carboxylic acid and ionic liquid (IL) mixtures were discussed in term of density and sound velocity measurements. The IL used in this study was 1-butyl-3-methylimidazolium thiocyanate ([BMIM]+[SCN]−). The density (ρ), and sound velocity (u), of the IL, acetic acid, propionic acid, and their corresponding binary systems {[BMIM]+[SCN]− (x1) + acetic or propionic acid (x2)} have been measured at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K and at p = 0.1 MPa. The excess molar volumes, View the MathML sourceVmE, isentropic compressibility, κs, and deviation in isentropic compressibility, Δκs, were calculated using experimental density and sound velocity data, respectively. The Redlich–Kister polynomial equation was used to fit the excess/deviation properties. These results are useful for describing the intermolecular interactions that exist between the IL and carboxylic acid mixtures.
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    Liquid–liquid equilibria measurements of ternary systems (acetonitrile + a carboxylic acid + dodecane) at 303.15 K
    (Elsevier, 2015) Redhi, Gan G.; Bahadur, Indra; Xhakaza, Nokukhanya Mavis
    Liquid–liquid equilibrium (LLE) data are reported for the ternary mixtures of (acetonitrile + a carboxylic acid + dodecane) at 303.15 K under atmospheric pressure, where a carboxylic acid refers to acetic acid, propanoic acid, butanoic acid, 2-methylpropanoic acid, pentanoic acid and 3-methylbutanoic acid. The area of the two-phase heterogeneous region for the carboxylic acid mixtures decreases in the order: acetic acid > propanoic acid > butanoic acid > 2-methylbutanoic acid > pentanoic acid > 3-methylbutanoic acid. The relative mutual solubility of each of the carboxylic acids is higher in acetonitrile layer than in dodecane layer. Three 3-parameter equations have been fitted to the binodal curve data. The NRTL and UNIQUAC models were used to correlate the experimental data. The NRTL model fitted the experimental data far better than the UNIQUAC model with the average mean square deviation of 0.0030 mole fraction as compared to 0.2870 mole fraction for UNIQUAC. Selectivity values for solvent separation efficiency were calculated from the tie-line data and show that separation of carboxylic acids from dodecane is feasible by extraction with acetonitrile.
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    Density and speed of sound of 1-ethyl-3-methylimidazolium ethyl sulphate with acetic or propionic acid at different temperatures
    (Elsevier, 2014-11) Singh, Sangeeta; Bahadur, Indra; Redhi, Gan G.; Ramjugernath, Deresh; Ebenso, Eno, E.
    In this work, new density, ρ, and speed of sound, u, were measured for IL, acetic acid, propionic acid, and their binary systems {IL (x1) + acetic or propionic acid (x2)} at 293.15, 298.15, 303.15, 308.15 and 313.15 K under at-mospheric pressure. The IL used in this study was 1-ethyl-3-methylimidazolium ethyl sulphate ([EMIM]+[EtSO4]−). The derived properties such as excess molar volumes, Vm, isentropic compressibility, κs, and deviation in isentropic compressibility, Δκs, were calculated using experimental density and speed of sound data, respectively. Derived properties such as excess molar volumes, Vm, and deviation in isentropic com-pressibility, Δκs, data were fitted to the Redlich–Kister polynomial equation. The measured and calculated data were interpreted on the basis of intermolecular interactions and structural effects between like and unlike mol-ecules upon mixing.