Ionic Liquids for Green Energy Applications - Local Structure and Dynamics by Advanced Spectroscopic Techniques

By definition ILs are molecular salts that melt at low temperatures, i.e. around room tem‐ perature or below 100 °C [2]. ILs also combine a remarkable set of properties such as high ion density (only ions!), wide temperature ranges of chemical and thermal stability, in‐ flammability and negligible vapor pressure. Hence ILs are particularly suitable for appli‐ cations where loss to the vapor phase limits the performance or constitutes an hazard, and have therefore been highlighted as the solvents for ”green chemistry” in industrial chemical processes [3]. More recently (and as we will see in this chapter), the application of ILs has extended to other fields like electrochemistry, food science and pharmacy [4, 5]. Yet another field of application for ILs is in the metal extraction process from waste water using emulsion ionic liquid membranes, where the IL contributes significantly to the membrane’s stability [6].