High-Pressure Density of Bis(1-alkyl-3-methylimidazolium) Tetraisothiocyanatocobaltate Ionic Liquids: Experimental and PC-SAFT with Volume-Shift Modeling


Tetraisothiocyanatocobaltate-based ionic liquids (ILs) have shown interesting thermophysical properties, mainly surprisingly low melting points and moderate viscosity. In addition, they have been tested to separate aromatics from aliphatics because of the high molar relation between cyano groups per molecule, with highlighted results. In this work, high-pressure density data (rho pT) were measured for bis(1-alkyl-3-methylimidazolium) tetraisothiocyanato-cobaltate ILs ([C(n)C(1)im](2)[Co(NCS)(4)]) (n = 1, 2) over wide ranges of temperature (283-363 K) and pressure (0.1-95 MPa). The new rho pT data and derivative properties, namely, the isothermal compressibility and isobaric expansivity, were successfully modeled with perturbed-chain statistical association fluid theory (PC-SAFT) and using the so-called volume shift, allowing us to propose a new molecular model and parameters for these solvents. The proposed model for tetraisothiocyanatocobaltate-based ILs is shown to be robust enough to model the phase equilibria of this new class of compounds.



subject category

Thermodynamics; Chemistry; Engineering


Navarro, P; Palma, AM; Garcia, J; Rodriguez, F; Coutinho, JAP; Carvalho, PJ

our authors


This work was developed in the scope of the CICECO-Aveiro Institute of Materials project, POCI-01-0145-FEDER-007679 (ref. FCT UID/CTM/50011/2013) funded by FEDER through COMPETE2020 Programa Operational Competitividade e Internacionalizacio (POCI) and by national funds through FCT Fundacao para a Ciencia e a Tecnologia. The authors are also grateful to Ministerio de Economia y Competitividad (MINECO) of Spain and Comunidad AutOnoma de Madrid for financial support of projects CTQ2017-85340-R and S2013/MAE-2800, respectively. P.N. and P.J.C. also thank the FCT for awarding their postdoctoral grant (SFRH/BPD/117084/2016) and contract under the Investigator FCT 2015 (IF/00758/2015), respectively. The authors thank KBC Advanced Technologies Limited (a Yokogawa Company) for the Multiflash thermodynamics package used in this work.

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