The Toxicological Impacts of Selected Ionic Liquids on Industrial Wastewater Treatment Bacteria

Samuel A. Morton III, Chemical Engineering, Lafayette College, 266 Acopian Engineering Center, Easton, TN 18042 and Maria A. Azimova, Department of Chemical Engineering, Lafayette College, 230 Acopian Engineering Center, Easton, PA 18042.

Ionic liquids are negligibly-volatile, thermally stable organic compounds with a wide array of potential applications in industrial processes. The nature and properties of these unique compounds support their use as replacement solvents for many large scale chemical processes. 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. A number of research efforts are underway to assess the toxicity of ionic liquids relative to human health and the environment. Since these compounds are increasingly likely to be adopted by the chemical industry, it is important to assess the effects of ionic liquids on 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 designed into normal wastewater treatment systems.

In this study, toxicity measurements were obtained for a selection of common room-temperature ionic liquids. These measurements were then correlated to the octanol-water partition coefficients, present in the literature as well as evaluated experimentally. The work presented in this study has shown that most ionic liquids exhibit levels of toxicity comparable with many common organic solvents. The understanding of the potential toxicity of these ionic liquids can be used to drive development of effective treatment and/or mitigation strategies that will allow for their industrial use while maintaining the integrity of industrial wastewater treatment systems.