Liquid phase behaviour in the binary system 1-ethyl-3-methylimidazolium ethylsulfate + alkane (n-heptane, methylcyclohexane, toluene)
Sustainable process-product development & green chemistry
Modelling of Ionic Liquids (T1-1)
Keywords: liquid-liquid equilibrium, ionic liquids, thermodynamic model, gnostic regression
Liquid phase behaviour in the binary system 1-ethyl-3-methylimidazolium ethylsulfate + alkane (n-heptane, methylcyclohexane, toluene)
Magdalena Bendová, Zdeněk Wagner
Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojová 135, 165 02 Prague 6, Czech Republic
e-mail bendova@icpf.cas.cz
Ionic liquids as possible greener an more efficient solvent alternatives to volatile organic compounds have been paid increased attention over more than a decade now. Their large number and tunability to required applications has already made them designer solvents. In addition, they can be used as lubricants, entrainers in extractive distillation, and due to their practically zero vapour pressure solvents utilisable at low to vacuum pressures.
In the present contribution, liquid-liquid equilibrium in three binary systems 1-ethyl-3-methylimidazolium (abbr. [emim][C2H5SO4]) + alkane is investigated. Two experimental methods are available in our laboratory: the volumetric and the direct analytical methods. Tie lines were obtained in previous work [1] by the volumetric method [2]. It consists of calculating the equilibrium compositions from the volumes of the equilibrium phases using simple mass balance formulas. To check the data, the direct analytical method was used to measure the solubility of the ionic liquid in the studied alkanes. This method consists of determining the compositions of the equilibrium phases by means of a suitable analytical method. As the imidazolium-based ionic liquids absorb UV rays, UV/Vis spectrophotometry was used to determine the contents of [emim][C2H5SO4].The data were also compared with those by Meindersma et al. [3].
The experimental data were subsequently described by the modified Flory-Huggins equation proposed by de Sousa and Rebelo [4] any by the molecular-thermodynamic lattice model proposed by Qin and Prausnitz [5]. The choice of these models primarily designed for mixtures of polymers is based on findings that ionic liquids swowed to some extent polymer-like behaviour [6, 7] and also on the previous succesful use of the modified Flory-Huggins equation in descriptions of thermodynamic properties of mixtures of ionic liquids[2, 8, 9]. Gnostic regression approach [2] was used to obtain parameters of the thermodynamic models.
References
1. Bendová, M. Distillation and Absorption 2006 ICheME Symposium Series 152, 2006, 574 – 580.
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9. Rebelo, L. P. N.; Najdanovic-Visak, V.; Visak, Z. P.; Nunes da Ponte, M.; Szydlowski, J.; Cerdeiriña, C. A.; Troncoso, J.; Romaní, L.; Esperança, J. M. S. S.; Guedes, H. J. R.; De Sousa, H. C. Green. Chem. 2004, 6, 369 – 381.
Acknowledgment
This work was supported by the Czech Science Foundation under grant No. 104/06/P066.
Presented Monday 17, 11:51 to 12:09, in session Modelling of Ionic Liquid Systems (T1-1).
