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Research Publications (Applied Sciences)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/213

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Author: search.filters.author.Ebenso, Eno, E.

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    Influence of temperature on molecular interactions of imidazolium-based ionic liquids with acetophenone: thermodynamic properties and quantum chemical studies
    (Royal Society of Chemistry, 2016) Bahadur, Indra; Masilo, Kgomotso; Ebenso, Eno, E.; Redhi, Gan G.
    The physicochemical properties namely: densities (ρ), sound velocities (u), viscosities (η), and refractive indices (nD) of a series of alkyl imidazolium-based ionic liquids (ILs) with same cation and different anion and vice versa of ILs: 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]+[BF4]−, 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM]+[PF6]−, 1-ethyl-3-methylimidazoium ethyl sulphate [EMIM]+[EtSO4]− and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM]+[BF4]−, with acetophenone over the wide range of composition and at (293.15, 303.15, 313.15, 323.5 and 333.15) K under atmospheric pressure is reported in this study. The excess molar volumes, (VEm), deviation in isentropic compressibilities (Δκs), deviation in viscosities (Δη) and deviation in refractive indices (ΔnD) were derived from experimental results. The VEm, Δκs and ΔnD values for the mentioned systems are both negative and positive over the entire composition range while the Δη values are negative under the same experimental conditions. The derived properties were fitted to the Redlich–Kister polynomial equation to check the accuracy of experimental results. Furthermore, the inter-ionic interactions between the cations and anions of the ILs both in vacuo and in acetophenone (using continuum solvation) were confirmed using quantum chemical technique such as [Density Functional Theory (DFT)]. The quantum chemical results are in good agreement with the experimental results suggesting that there exist appreciable interactions between the ILs and acetophenone. The theoretical and measured data were interpreted in terms of intermolecular interfaces and structural effects between similar and dissimilar molecules upon mixing in order to obtain more information on the thermophysical and thermodynamic properties of ILs and their binary mixtures. This study will contribute to the data bank of thermodynamic properties of IL mixtures, so as to establish principles for the molecular design for chemical separation processes and to enhance the applications of ILs in certain aspects of research or industrial application.
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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.