Progress in evaluation of risk potential of ionic liquids—basis for an eco-design of sustainable products

Abstract

Motivated by the prevailing need for a sustainable development and taking the principles of Green Chemistry as a starting point, the present paper describes new and updated findings regarding a sustainable product design for ionic liquids. The focus is on environmental risk. Nevertheless, cytotoxicity testing and first indicative results from a genotoxicity study extend present knowledge also with regard to possible effects on humans. The structural variability of commercially available ionic liquids as well as the abundance of theoretically accessible ionic liquids is illustrated and the consequences for an integrated risk assessment accompanying the development process are discussed. The side chain effect on toxicity for imidazolium type ionic liquids was confounded by more complex biological testing. Also, an influence of an anion on cytotoxicity is shown for the first time. Testing of presumed metabolites of the imidazolium type cations showed a significantly lower biological activity in cytotoxicity studies than their parent compounds. The importance of a purity assessment for ionic liquids is pointed out and a collection of methods that is believed to be adequate is presented. In addition to risk analysis, the use of life cycle analysis for the multi-objective problem of designing ionic liquids is sketched and an eco-design scheme for ionic liquids is proposed. In conclusion, the paper illustrates the complex nature of the development processes ionic liquids are currently undergoing and provides guidance on which aspects have to be kept in mind.

Physicochemical properties and toxicities of hydrophobic piperidinium and pyrrolidinium ionic liquids

“…There is growing interest in cytotoxicities, in aqueous environmental impact as well as in structureactivity relationship for ILs. [17][18][19][20][21][22][23][24][25][26][27][28] Only few reports have used human cancer cells. 18,22,26 For extraction of organic solutes or offensive metallic cations from water, we require highly hydrophobic ionic liquids that have very low solubility in water.…”

Biodegradable, non-bactericidal oxygen-functionalised imidazolium esters: A step towards ‘greener’ ionic liquids

“…Toxicity and antimicrobial studies have been performed on a range of bacteria and fungi, 14-17 acute toxicity studies have been carried out on fish, 18 growth inhibition studies have been carried out on algae, 19,20, 21 and also on terrestrial plants. 22, 23 The variety of organisms studied now extends to higher classes such as the soil nematode 24 and the freshwater snail.…”

A New Salt Bridge Based on the Hydrophobic Room-Temperature Molten Salt

“…While KCl is safe and chemically fairly inert, the risk potential of ionic liquids are currently under scrutiny. [34][35][36] In the present study, C 8 mimC 1 C 1 N was chosen as a representative of RTMSs that form a nonpolarized interface with an aqueous phase. Moderately hydrophobic ions, in particular anions, are potentially uncouplers in biological systems and must be handled with care.…”