Inventory of biodegradation data of ionic liquids. (July 2022)

• Record Type: Journal Article
• Authors: Amsel, Ann-Kathrin; Olsson, Oliver; Kümmerer, Klaus
• Is Part Of: Chemosphere. Volume 299(2022)
• Publication Date: 2022-07
• Subjects: Ionic liquids -- Ready biodegradability -- OECD 301 -- ISO 14593 -- Green and sustainable chemistry; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.134385
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Ionic liquids (ILs) are increasingly of interest for environmentally open applications. Therefore, completely mineralising ILs are highly desirable. We reviewed the current state of knowledge on ILs' environmental biodegradability and identified research needs. Literature data were evaluated as for applied standard methods (e.g. OECD, ISO, APHA) for biodegradation of ILs in order to get an overview on the validity of the test results received and ILs' biodegradability. 109 studies were evaluated. The ILs were categorised based on the cation's core structure. The biodegradation data was classified according to a traffic light system (red: 0–19% degradation, amber: 20–59% degradation, green: ≥ 60% degradation). Not all studies could be assessed for compliance with the test guidelines due to missing test parameters. Moreover, no study discussed all validation criteria as defined by the test guidelines. Consequently, the reliability and quality of the existing biodegradation data is restrained. With regard to the different cations classified for ≥ 60% biodegradability, phosphonium ILs are the least biodegradable, followed by imidazolium ones. The most ILs that were biodegradable are cholinium ILs. The results indicate the need for more and qualitatively better testing according to standard methods including application and reporting of all validation criteria in order to get reliable data that enables the comparison of the test data and a comprehensive understanding of ILs' biodegradability. Moreover, reliable data allows the selection of sufficiently environmentally biodegradable ILs if an introduction into the environment during use cannot be excluded. Graphical abstract: Image 1 Highlights: Review delivered 109 ILs biodegradation studies that applied standardised methods. Methods were evaluated on compliance with the guidelines, validity of the data. Biodegradation data on 716 different ILs including 29 ILs mixtures were provided. 34 ILs classified as readily biodegradable in accordance with the guidelines. More valid ILs biodegradation data based on standard methods needed.