Separation of binary mixtures based on limiting activity coefficients data using specific ammonium-based ionic liquid and modelling of thermodynamic functions

摘要

Thermodynamic properties of quaternary ionic liquid (IL),N-benzyl-N-dimethyl-N-tetradecylammonium cinnamate, [NBz,1,1,14][Cyn] were investigated by the inverse chromatography with 65 different solvents: alkanes (C5-C10), cycloalkanes (C5-C8), alkenes (C5-C10), alkynes (C5-C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene,o-,m-,p-xylene, thiophene), alcohols (C1-C5), water, ethers (diethyl-, di-n-propyl-, di-n-butylether, methyl-tert-butylether, MTBE, tetrahydrofuran, THF) and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) at five temperatures ranging from (328.15–368.15) K. The limiting activity coefficients, the thermodynamic functions, the limiting partial molar excess Gibbs energy, enthalpy and entropy were calculated. The values of selectivity and capacity for water/butan-1-ol, water/ethanol, water/THF, water/1,4-dioxane and many others separation problems were calculated fromγ13∞and compared to literature values for selected ionic liquids. On the basis of the results, the intermolecular interactions of the chosen IL and solutes were discussed. The data presented here shows that [NBz,1,1,14][Cyn] reveals very large selectivity for the hexane/ethanol and heptane/ethanol separation. It allows expanding our knowledge about nature of the [NBz,1,1,14][Cyn], influence of polar functional groups and the structure on thermodynamical properties of [NBz,1,1,14][Cyn] and designing suitable solvent for specific extraction problem. It was shown earlier in many data that the selectivities of ammonium-based ILs in separating organic liquids are often higher than those for commonly used solvents. However, the examination has to be always done of the selectivity together with capacity for a variety of solute in entrainers to provide a picture of interactions and costs.