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Title: Application of selected ionic liquids for different separation problems : liquid-liquid equilibria and activity coefficients at infinite dilution
Authors: Kabane, Bakusele 
Issue Date: 2021
This work focusses on the application and pre-screening of selected ILs for different industrial separation problems based on limiting activity coefficients at infinite dilution,
and liquid-liquid equilibrium data at different temperatures. The selected ionic liquids for
pre-screening based on activity coefficients at infinite dilution data include (1,3-
dimethyimidazolium dimethylphosphate, trioctylmethylammonium chloride,
trihexyltetradecylphosphonium dicyanamide, 2,3-dihydroxypropyl-N-methyl-2-
oxopyrrolidinium chloride, 2,3-epoxypropyl methyl-2-oxopyrrolidinium chloride) and deep
eutectic solvent (1-butyl-3-methylimidazolium chloride + glycerol) at 1:2 molar ratio. These
ionic liquids were tested in 33 solutes (alkanes, alkenes, alkynes, alcohols, tetrahydrofuran,
ketones, aromatic hydrocarbons, thiophene, acetonitrile) and water at T = (313 – 343) K and
at p = 101 kPa. The use of ionic liquid as a stationary phase on the column loading ranged
between (30 – 36) % by mass.
Thermodynamic functions at infinite dilution such as (Gibbs free energy,
, entropy
term, Tref
and partial molar enthalpy,
) were also computed to further elucidate
the types of intermolecular interactions existing between solutes and the investigated ionic
liquids. The separation potential of the ionic liquids was determined from the selectivity
), and capacity (
), values. Different ionic liquids (1-ethyl-3-methylimidazolium
tetrafluoroborate, 1-ethyl-3-methylimidazolim dicyanamide, 1,3-dimethylimidazolium
dimethylphosphate) were also tested in the separation of azeotropic mixture (ethyl
acetate/hexane) and in the desulfurization (thiophene/hexadecane or octane) process.
The extraction process was conducted at varying temperatures, T = (308 and 298) K and at p
= 101 kPa. The results were compared to previously published ionic liquids involving thermodynamic data found in the literature. The separation capacity was based on the
calculated values of selectivities (S) and distribution ratio (β). The data was successfully
correlated using the thermodynamic non-random two liquids (NRTL). From this study, it was
found that the investigated ionic liquids showed some possible application for selected
industrial separation problems.
Submitted in the fulfilment of the academic requirements for the degree of Doctor of Philosophy in Chemistry, Faculty of Applied Sciences, Department of Chemistry, Durban University of Technology, 2021.
Appears in Collections:Theses and dissertations (Applied Sciences)

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