A. Arce, M. Earle, H. Rodríguez
Dec 1, 2008
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Journal
Green Chemistry
Abstract
The ionic liquid 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide ([C2mim][NTf2]) was tested as solvent for the separation of aromatic and aliphatic hydrocarbons containing 7 or 8 carbon atoms (the C7- and C8-fractions). The liquid–liquid equilibria (LLE) of the ternary systems (heptane + toluene + [C2mim][NTf2]) and (octane + ethylbenzene + [C2mim][NTf2]), at 25 °C, were experimentally determined. The performance of the ionic liquid as the solvent in such systems was evaluated by means of the calculation of the solute distribution ratio and the selectivity. The results were compared to those previously reported for the extraction of benzene from its mixtures with hexane by using the same ionic liquid, therefore analysing the influence of the size of the hydrocarbons. It was found that the ionic liquid is also good for the extraction of C7- and C8-fraction aromatic compounds, just a greater amount of ionic liquid being needed to perform an equivalently efficient separation than for the C6-fraction. It is also discussed how [C2mim][NTf2] performs comparably better than the conventional solvent sulfolane. The original ‘Non-Random Two-Liquid’ (NRTL) equation was used to adequately correlate the experimental LLE data.