Ecotoxicity of Choline Ionic Liquids with Different Anions

Five choline ionic liquids were selected to evaluate their toxicity to green alga (Chlorella vulgaris) and Daphnia magna. Their influence on chlorophyll content, respiration rate, antioxidase activity, and malondialdehyde content of Chlorella vulgaris and the acute and chronic toxicity of Daphnia magna were investigated. The studied ionic liquids slightly inhibited the algal growth with the median effective concentrations (EC50) > 1900 mg/L. Chlorophyll contents, respiration rate, and protein contents of the alga after 96 h of exposure decreased with the higher concentrations of the ionic liquids, while superoxide dismutase and catalase activity and malondialdehyde content increased firstly and then decreased. The acute toxicity of Daphnia magna after 48 h of exposure (indicated by the median effective concentrations, EC50) was 200.44 and 184.50 mg/L for choline acetate and choline D-lactate, respectively, which was above the toxicity of other ionic liquids. The studied ionic liquids presented low toxicity to Chlorella vulgaris and Daphnia magna.