Radiation Effect of Carboxyl-Functionalized Task-Specific Ionic Liquids on UO₂²⁺ Removal: Experimental Study with DFT Validation

Experimental study with DFT validation on the effect of radiation on 1-carboxymethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl) imide ([HOOCCH₂MIM]­[NTf₂]) as a solvent and extractant in rapid homogeneous extraction of UO₂²⁺ was performed for the first time. The radiolytic products of the anions and cations of [HOOCCH₂MIM]­[NTf₂] were identified by ¹⁹F NMR and high-resolution ESI-MS, respectively, and they were attributed to a decrease in UO₂²⁺ partitioning. Experimental study with DFT validation for complexing reactions between [HOOCCH₂MIM]­[NTf₂] and radiolytic products proved that F^– competition was one of the main reasons for the decrease in UO₂²⁺ partitioning. However, UO₂²⁺ partitioning in irradiated [HOOCCH₂MIM]­[NTf₂] can largely be recovered after thorough water washing because of the removal of radiolytic products of [NTf₂]⁻.