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

Abstract The activity coefficients at infinite dilution, γ 13 ∞ and gas-liquid partition coefficients, K L 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 Δ G 1 E, ∞ , enthalpies Δ H 1 E, ∞ and entropies Δ S 1 E, ∞ at infinite dilution were calculated from the experimental γ 13 ∞ values obtained over the temperature range. The selectivities and capacities at infinite dilution for water/butan-1-ol separation problem were calculated from the γ 13 ∞ 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 K L 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.