Micro-scale processes occurring in ionic liquid–water phases during extraction

Abstract For the first time, extraction process in ionic liquids was visualized by direct electron microscopy observation. Microscopy images revealed the micro-heterogeneous nature of the studied extraction systems. Depending on the nature of ionic liquids and studied compounds, four main systems were observed at micro-scale level: (a) uniform homogeneous phase; (b) microcompartments in the liquid phase; (c) solid microinclusions on the phase boundary; and (d) solid microinclusions inside the separated microphases. The microscopic monitoring showed the stepwise sequence of the extraction process, and the retention ability of the ionic liquid–water system decreased in the following order: homogeneous phase > microcompartments > solid microinclusions.