Alkyl chain length affecting uptake of imidazolium based ionic liquids by ryegrass (Lolium perenne L.).

Imidazolium based ionic liquids (ILs) have been extensively used in the various industrial fields, however, the dependence of their structure on toxicity and bioavailability by plants is not clear. Thus, in this study, uptake of imidazolium based ILs with different alkyl chain lengths (e.g., [C ₂ mim] ⁺ and [C ₈ mim] ⁺ ) by ryegrass and their toxicity to plant growth were investigated. Results show that the two ILs could be removed by ryegrass with high efficiencies, and a higher uptake efficiency and accumulation was observed for [C ₂ mim] ⁺ with shorter chain length compared with that for [C ₈ mim] ⁺ . A higher growth inhibition of ryegrass by [C ₈ mim] ⁺ was observed compared with that by [C ₂ mim] ⁺ , indicating the long alkyl chain length of ILs had a negative effect on the plant growth. ILs taken up by ryegrass was retained in the roots and their translocation from roots to shoots was restricted. The IL concentration in roots was 0.68 mg/g-fresh weight for [C ₂ mim] ⁺ and 0.08 mg/g- fresh weight for [C ₈ mim] ⁺ when the ryegrass was exposed to 10 mg/L ILs. This study proved that plant assimilation of ILs depended on their alky chain lengths, which would be useful for understanding the fate of ILs with various structures in phytoremediation for ILs-contaminated water.
(Copyright © 2020 Elsevier B.V. All rights reserved.)