Room temperature ionic liquids (ILs) are liquid salts at room temperature. They are usually composed of large asymmetric organic cations and inorganic or organic anions. Most commonly considered for extraction and synthesis are those with cations based on the imidazolium or pyridinium ring with one or more alkyl groups attached to the nitrogen or carbon atoms [1]. ILs have many fascinating properties including: wide liquid ranges, low volatilities (negligible vapor pressure), good thermal stabilities, electrolytic conductivity, wide range of viscosities, adjustable miscibility, reusability, non-flammability and so on [2]. Due to their negligible vapor pressure and electrolyte properties, they can be applied as replacements for conventional toxic, flammable and volatile organic solvents, and become very interesting entrainers in separation processes (e.g. extractive distillation, liquid–liquid extraction and absorption) [3]. From a physical point of view, ILs are complex (and more difficult to understand) because they combine properties from two vastly different types of materials: molten salts (e.g. NaCl above 801 °C) and organic liquids (e.g. molecular solvents like benzene or cyclohexane) [4].