ABSTRACT
Unlike water-soluble compounds that can be extracted with water, or the removal of chemicals with high vapor pressures by distillation, ionic liquids require very high temperatures to effect separation of compounds. This post-separation of chemical products from ionic liquids may be difficult to achieve since the heat needed may cause the products to degrade. Furthermore, the energy needed to drive these reactions may be too expensive. If these problems can be solved, ionic liquids may become safer, greener solvents since they do not possess any measur-
able vapor pressure and so, unlike chlorinated/organic solvents, do not evaporate to be inhaled by workers or to be emitted into the atmosphere and cause air pollution. (The dermatological consequences of exposure to ionic liquids as well as their impact on water pollution are currently unknown.)
To address this separation issue, Brennecke and Beckman performed experiments using a combination of an ionic liquid and supercritical carbon dioxide at room temperature [5]. Their experiment, first reported in 1999, is diagramed in Figure 5.
