Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

Activity coefficients at infinite dilution (c1 i ) and (gas-liquid) partition coefficients (KL) for organic compounds (alkanes, alkenes, alkyl benzenes, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, 1,4- dioxane, chloromethanes, and alcohols) in the ionic liquid (IL) 1-octyl-2,3-dimethylimidazolium bis(tri fluoromethylsulfonyl)imide ([OMMIM][NTf2]) have been measured by the gas-liquid chromatographic (GLC) method in the temperature range of (313.15 to 353.15) K. Density, q as a function of temperature for [OMMIM][NTf2] at pressure p 1/4 101:3 kPa were measured. The values of the partial molar excess enthalpies at infinite dilution ( HE;1 i ) were derived from the temperature dependence of the c1 i values. The entropies (Tref SE;1 i ) and Gibbs energies ( GE;1 i ) of organic solutes in [OMMIM][NTf2] at a reference temperature Tref 1/4 298:15 K were also calculated from the c1 i values. The Hildebrand s solubility parameters of the IL [OMMIM][NTf2] were also determined by the regular solution theory (RST) combined with Flory combinatorial equation. The linear free energy relationship (LFER) analysis of the results was performed to disclose molecular interactions operating between the IL and the individual solutes. Selectivity (Sij1) and capacity (k1 j ) at infinite dilution at 323.15 K have been determined for n-hexane (i)/benzene (j), cyclohexane (i)/benzene (j) and compared to literature values for [NTf2]-based ILs for the same separation problems. For three isomeric xylenes separation problems, Sij1 at 323.15 K was also obtained from the c1 i values.