Copper-uptake mediated by an ecofriendly zwitterionic ionic liquid: A new challenge for a cleaner bioeconomy

This study aims to investigate the ability of an imidazolium biobased Zwitterionic Ionic Liquids (ZILs) in enhancing the phytoavailability of copper from garden (G) and vineyard (V) soils using the model plant ryegrass. Uncontaminated and artificially contaminated CuSO4 soils, unamended and ZIL-amended soil modalities were designed. The copper/ZIL mo-lar ratio (1/4) introduced was rationally established based on molecular modeling and on the maximal copper concentration in artificially contaminated soil. Higher accumulation of copper in the shoots was detected for the uncontaminated and copper contaminated ZIL amended V soils (18.9 and 23.3 mg/kg, respectively) contrary to G soils together with a ZIL concentration of around 3% (W/W) detected by LC-MS analyses. These data evidenced a Cu-accumulation improvement of 38% and 66% compared to non-amended V soils (13.6 and 13.9 mg/kg respectively). ZIL would be mainly present under Cu(II)-ZIL4 complexes in the shoots. The impact on the chemical composition of shoot was also studied. The results show that depending on the soils modalitity, the presence of free copper and/or ZIL led to different chemical compositions in lignin and monomeric sugar contents. In the biorefinery context, performances of enzymatic hydrolysis of shoots were also related to the presence of both ZIL and copper under free or complex forms. Ecotoxicity assessment of the vineyard soil samples indicated that the quantity of copper and ZIL remaining in the soils had no sig-nificant toxicity. ZIL amendment in a copper-contaminated soil was demonstrated as being a promising way to promote the valorization of phytoremediation plants.(c) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

The study investigates the efficacy of imidazolium biobased Zwitterionic Ionic Liquids (ZILs) in enhancing copper phytoavailability from garden and vineyard soils. Different soil modalities with and without ZIL amendment were designed, and copper/ZIL molar ratio was rationalized based on molecular modeling. The results showed higher copper accumulation in shoots for ZIL amended vineyard soils compared to garden soils, and ZIL mainly existed in Cu(II)-ZIL4 complexes. The chemical composition of shoots and enzymatic hydrolysis performance were influenced by the presence of free copper and/or ZIL in the soils. The ecotoxicity assessment indicated no significant toxicity from the copper and ZIL remaining in the soils. ZIL amendment in copper-contaminated soil showed promise in promoting phytoremediation plant valorization.