Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid 4-(2-methoxyethyl)-4-methylmorpholinium trifluorotris(perfluoroethyl)phosphate

Abstract

This paper presents new data on activity coefficients at infinite dilution, γ∞ for 62 different solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, and water in the ionic liquid 4-(2-methoxyethyl)-4-methylmorpholinium trifluorotris(perfluoroethyl)phosphate, [COC2mMOR][FAP]. The data were determined by inverse gas chromatography at six temperatures from T=318.15K to T=368.15K. These values were compared with ionic liquid based on the same cation and bis(trifluoromethylsulfonyl)-amide anion, [COC2mMOR][NTf2]. Additionally the partial molar excess Gibbs free energies ΔG1E,∞, enthalpies ΔH1E,∞, and entropies ΔS1E,∞ at infinite dilution were calculated from the experimental γ∞ values obtained over the temperatures range. The selectivities and capacities at infinite dilution for hexane/benzene, cyclohexane/benzene, and heptane/thiophene extraction problems were calculated from the γ∞ to verify the possibility of investigated ionic liquid as an entrainer in liquid–liquid extraction and desulphurization of fuels. Obtained values were compared with literature data of other ionic liquids based on trifluorotris(perfluoroethyl)phosphate and bis(trifluoromethylsulfonyl)-amide anions and industrial solvents: NMP and sulfolane. Also the Abraham solvation parameter model was used for evaluation of the solvation characteristic of the ionic liquid. Linear free energy relationship (LFER) system constants as a function of temperature were calculated.