Towards understanding the color change of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide during gamma irradiation: an experimental and theoretical study

Abstract

The application of room-temperature ionic liquids (RTILs) in nuclear spent fuel recycling requires a comprehensive knowledge of radiation effects on RTILs. Although preliminary studies indicate a relatively high radiation stability of RTILs, little attention is paid to the color change of RTILs, an obvious phenomenon of RTILs during irradiation. In this paper, we have investigated radiation-induced darkening and decoloration of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIm][NTf2]), an ionic liquid representing the most popular class of RTILs, by means of UV-Vis analysis and time-dependent density functional theory calculations. Based on the experimental and computational results, it is proposed that the color change of [BMIm][NTf2] upon irradiation originates from the formation of double bonds in the aliphatic chains of pristine organic cations (or radiolytic products of RTILs) and various associated species containing these "double-bond products". This work sheds light on the understanding of the radiation-induced color change of RTILs.

Comparative uptake studies on trivalent f-cations from acidic feeds using two extraction chromatography resins containing a diglycolamide in molecular diluent and ionic liquid

“…The S-O stretch is expected at around 1150 cm −1 . The two peaks at 3105 cm −1 and 3152 cm −1 refer to the C-H stretching bands in the imidazolium ring [32] . A careful observation of the FTIR spectra (supporting information) confirms the presence of the ionic liquid inside the resin pores.…”

Selective Liquid‐Liquid Extraction of Uranium by Phosphoramidate‐Group Bearing Ionic Liquid

“…The synthesized TSIL (viscosity; η determined =2836±8 cP at 298 K) being highly viscous has been diluted in 1‐Butyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide ([C 4 mim][NTf 2 ]; η reported =50.34 cP at 298 K) medium and then used in LLE procedure. The diluent ionic liquid viz., [C 4 mim][NTf 2 ] has been choosen by considering its chemical stability towards concentrated HNO 3 medium, very low viscosity compared to the TSIL, low water solubility and α and γ radiation stability . Increase or decrease in the alkyl chain length or branching of the cationic part of this ionic liquid would result in either higher viscosity or higher water solubility.…”

Optical properties of irradiated imidazolium based room temperature ionic liquids: new microscopic insights into the radiation induced mutations

“…Similar types of products were noticed in the case of the irradiated FAP1 IL. 9 Moreover, recently, Wang et al,12a by means of UV-Vis analysis and density functional theory calculations, proposed that the color darkening in imidazolium based IL [BMIm][NTf 2 ] upon irradiation originates from the formation of double bonds in the aliphatic chains of pristine organic cations (or radiolytic products of RTILs) and various associated species containing these ''double bond products''. Therefore, our vibrational analysis provides direct evidence for the formation of aforesaid radiolytic products containing double bonds, which eventually might act as chromophoric units.…”