Pyrrolidinium-based Ionic Liquids: Aquatic Ecotoxicity, Biodegradability, and Algal Subinhibitory Stimulation

Pyrrolidinium imides are considered among the most promising electrolytes for the development of novel and sustainable portable energy devices. Because of this widespread potentiality, a risk scenario of an erroneous disposal of ionic liquids-based batteries in the environment has to be taken into account. In the present study, some of the best energy performing pyrrolidinium-based ionic liquids were evaluated in terms of persistence in aquatic environments and hazard toward freshwater organisms (crustacean Daphnia magna and unicellular green alga Raphidocelis subcapitata). The examined ionic liquids were not aerobically biodegradable (biodegradation less than 5% in 28 days), but they demonstrated low toxicity toward algae and crustaceans, according to the standard bioassay end points (EC50 > 100 mg L-1). However, ionic liquids were able to alter the cellular morphology of R subcapitata and an increased amount of proteins (30%) was observed in the exposed cells, suggesting an inhibition of cellular division.