Ionic liquids are non-volatile, thermally stable organic compounds with a wide array of potential applications in industrial processes. Many of the useful properties of ionic liquids, such as high polarity, varying degrees of solubility in organic compounds, significant electrical conductivity, thermal stability, and negligible vapor pressure, support their use as replacement solvents and/or catalysts for many synthetic reactions. Due to the potential wide-spread use of the ionic liquids, the question of their environmental impact has been a pressing matter for several years. It is therefore important to assess the effects of ionic liquids on the common wastewater treatment bacteria. The reason for this is twofold: (1) based on this information disposal techniques for ionic liquids can be developed, and (2) the impacts of an ionic liquid release from a process upset can be design into normal wastewater treatment systems.

A series of experiments have been conducted using relevant assays to estimate the toxicity of selected imidazolium-based ionic liquids. Our results show that these compounds will be toxic to wastewater treatment bacteria. Further analysis has been performed on the synthesis of ionic liquids to categorize the environmental impact using green engineering techniques. A discussion of new developments will also be covered.