Acute toxicity and effects of 1-alkyl-3-methylimidazolium bromide ionic liquids on green algae

In the present study, the acute toxicity of 1-Alkyl-3-methylimidazolium bromide ([C(n)mim]Br) on the green algal Scenedesmus obliquus and Chlorella ellipsoidea was determined. The length of alkyl side chain of these imidazolium ionic liquids were C-4, C-6, C-8, C-10 and C-12. The primary production of S. obliquus was also assessed after they were exposed to 0.01, 0.05, 0.10, 0.50 and 1.00 mg/L of [C(10)mim]Br for 96 h. The results showed that the acute toxicity of these ionic liquids was positively correlated with the alkyl chain length. Meanwhile, the concentration of the ionic liquid strongly influenced the primary production of algae. These results indicate that [C(n)mim]Br with longer alkyl length have toxic effects on the green algae, and the risk to aquatic ecosystems by ionic liquid's leaking into the water body must be evaluated in the future. (C) 2009 Elsevier Inc. All rights reserved.