Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid trihexyl-tetradecyl-phosphonium tricyanomethanide

The activity coefficients at infinite dilution, γ13∞ and gas-liquid partition coefficients, KL for 62 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, butanal, nitrogen compounds and water in the ionic liquid trihexyl-tetradecyl-phosphonium tricyanamide were determined by gas-liquid chromatography at the temperatures from 328.15 K to 368.15 K. The partial molar excess Gibbs energies ΔG1E,∞, enthalpies ΔH1E,∞ and entropies ΔS1E,∞ at infinite dilution were calculated from the experimental γ13∞ values obtained over the temperature range. The selectivities and capacities at infinite dilution for water/butan-1-ol separation problem were calculated from the γ13∞ and compared to the literature values for other ionic liquids. High selectivity was obtained in comparison to other ionic liquids. Butanol is considered as possible biofuel. This alcohol is produced by fermentation and it must be separated from the aqueous fermentation broth. The values of KL were used to determine the linear free energy relationship (LFER) system constants as a function of temperature. The density of the investigated ionic liquid was also measured at temperatures from 298.15 K to 368.15 K.