Limiting Activity Coefficients and Gas–Liquid Partition Coefficients of Various Solutes in Piperidinium Ionic Liquids: Measurements and LSER Calculations

This paper is a continuation of our systematic investigations on piperidinium ionic liquids and presents new data on activity coefficients at infinite dilution for 43 solutes: linear and branched alkanes, cycloalkanes, alkenes, alkynes, benzene, alkylbenzenes, alcohols, water, thiophene, tetrahyrdofuran (THF), methyl tert-butyl ether (MTBE), linear ethers, acetone, and linear ketones in the ionic liquid 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide, [BMPIP][NTf2]. The data were determined by gas–liquid chromatography (GLC) at temperatures from 308.15 to 358.15 K. These values were compared to those previously published for the bis(trifluoromethylsulfonyl)imide-based ionic liquids. The partial molar excess enthalpies ΔH 1 E,∞ and entropies ΔS 1 E,∞ at infinite dilution were calculated from the experimental γ13 ∞ values obtained over the temperature range. The values of the selectivities for different separation problems were calculated from γ13 ∞ and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and additional ionic liquids. Experimental limiting activity coefficients were used to calculate gas-IL partition coefficients of solutes, K L. The modeling with specific linear solvation energy relationship (LSER) equations was performed for data obtained in this work and those reported earlier for 1-butyl-1-methylpiperidinium thiocyanate, [BMPIP][SCN].