Application of mutually immiscible ionic liquids to the separation of aromatic and aliphatic hydrocarbons by liquid extraction: a preliminary approach

The recently discovered class of ionic liquids-mutually immiscible ionic liquids-are explored in this work for their first practical application: the separation of aromatic and aliphatic hydrocarbons by solvent extraction. For this preliminary approach, benzene and hexane were chosen as representatives of each group of hydrocarbons; the ionic liquids 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide and trihexyl(tetradecyl)phosphonium bis{(trifluoromethyl)sulfonyl}amide, which are both liquid at room temperature and hydrophobic, were selected as potential solvents. Liquid-liquid equilibrium experiments were carried out at 25 degrees C for the quaternary system formed by the two hydrocarbons and the two ionic liquids. Typical extraction parameters were calculated and analysed in order to evaluate the possibilities of the mutual immiscible ionic liquids in accomplishing the separation target. A comparison with the case of using just one of the ionic liquids was made.