Phase equilibria study of the (N-octylisoquinolinium thiocyanate ionic liquid + aliphatic and aromatic hydrocarbon, or thiophene) binary systems

• The LLE for n-alkanes and aromatic hydrocarbons in [C8iQuin][SCN] have been determined.
• The NRTL equation was used to correlate experimental data.
• The influence of the ionic liquid structure on mutual solubility was discussed.

Binary liquid + liquid phase equilibria for 8 systems containing N-octylisoquinolinium thiocyanate, [C8iQuin][SCN] and aliphatic hydrocarbon (n-hexane, n-heptane), cyclohexane, aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene) and thiophene have been determined using dynamic method. The experiment was carried out from room temperature to the boiling-point of the solvent at atmospheric pressure. For the tested binary systems the mutual immiscibility with an upper critical solution temperature (UCST) for {IL + aliphatic hydrocarbon, or thiophene} were observed. The immiscibility gap with lower critical solution temperature (LCST) for the {IL + aromatic hydrocarbon} were determined. The parameters of the LLE correlation equation for the tested binary systems have been derived using NRTL equation. The phase equilibria diagrams presented in this paper are compared with literature data for the corresponding ionic liquids with N-alkylisoquinolinium, or N-alkylquinolinium cation and with thiocyanate – based ionic liquids. The influence of the ionic liquid structure on mutual solubility with aliphatic and aromatic hydrocarbons and thiophene is discussed.

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