Phase equilibria of water and ionic liquids [emim][PF6] and [bmim][PF6]

In this work, solid-liquid and liquid-liquid equilibria of [emim][PF6] + water and liquid-liquid equilibria of [bmim][PF6] + water are studied using DSC, Karl-Fischer analysis, UV and DSC. An eutectic melting point for [emim][PF6] + water is found at 314 K with about 5 wt.% of water. The solubility of [emim][PF6] in water increases from about 5 wt.% at 308 K to 8 wt.% at 323 K. The solubility of water in liquid [emim][PF6] is around 5 wt.% and relatively independent of temperature. The solubility of [bmim][PF6] in water measured by UV increases from 2.4 wt.% at 303 K to 3.7 wt.% at 323 K. The solubility of water in [bmim][PF6] measured by Karl-Fischer increases from 2.67 wt.% at 303 K to 3.70 wt.% at 323 K. (C) 2002 Published by Elsevier Science B.V.