Measurement of activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-hexyl-1,4-diaza[2.2.2]bicyclooctanium bis(trifluoromethylsulfonyl)imide using gas-liquid chromatography

Based on gas-liquid chromatography (GLC) retention data, activity coefficients at infinite dilution of 39 different solutes in the ionic liquid 1-hexyl-1,4-diaza[2.2.2]bicyclooctanium bis(trifluoromethylsulfonyl)imide ([HDABCO][NTf2]) have been determined. Measurements covered a broad range of types of organic solutes including alkanes, alcohols, ketones, benzene derivatives and McReynold's compounds. Activity coefficients were measured over the temperature range (331.15-363.15) K. The partial molar excess enthalpies of mixing at infinite dilution have been determined based on Gibbs-Helmholtz relationship. Selectivity at infinite dilution values have been also calculated for exemplary separation processes in the systems hexane/benzene and cyclohexane/benzene. The results obtained were analyzed in comparison to literature data for ionic liquids with the same [NTf2]− anion. The obtained results indicate the potential for the application of the investigated ionic liquid in separation problems.