Volumetric and sound speed study of ammonium-based ionic liquid mixtures with ethanol

• Published in: The Journal of chemical thermodynamics Vol. 104; pp. 118 - 127
• Main Authors: Santos, Ângela F.S., Moita, Maria-Luísa C.J., Silva, João F.C.C., Lampreia, Isabel M.S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2017
• Subjects: Ammonium-based ionic liquids; Ethanol; Excess molar volumes and isentropic compression; Packing effects; Specific interactions; Excess molar volumes and isentropic compression; Ammonium-based ionic liquids; Specific interactions; Packing effects; Ethanol
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/j.jct.2016.09.024

[Display omitted] •Densities and sound speeds were measured at five temperatures in three ammonium-based ionic liquids mixtures with ethanol.•Excess molar and limiting molar and partial molar properties were derived and interpreted.•Specific interactions and packing effects were compared in the three systems.•Reduced variables were used to highlight differences in cation size and solvophilic effects. Thermodynamic studies embracing molecular interactions between ionic liquids (ILs) and molecular solvents are scarce and are required to explore molecular interactions and structural effects with interest in engineering applications. Ammonium-based are interesting ILs since they can be tailored to provide information concerning both chain length and solvophobic/solvophilic effects. In this work from accurately measured density and sound speed data in the systems ethanol+{[N4111]; [N4441] or [choline]}[NTf2] derived quantities such as excess partial molar volumes and isentropic compressions including their limiting values were obtained. The reasoning of the results permitted to conclude that while in the [N4441][NTf2] case packing effects due to the difference in size of the components prevail, in the other two cases specific interaction ethanol–cation explains both the lower minimums in the excess properties and the higher magnitude of the negative limiting excess partial molar, volumes and isentropic compression values in the mixture containing [N4111][NTf2] in relation to [N4441][NTf2] and the negative limiting partial molar isentropic compression in the [choline][NTf2] case in contrast with positive values for the other two ILs.