Radiolysis of crown ether–ionic liquid systems: identification of radiolytic products and their effect on the removal of Sr²⁺ from nitric acid

Abstract

The quantitative analysis and identification of the radiolytic products of dicyclohexano-18-crown-6 (DCH18C6), 4',4''(5'')-di-tert-butyldicyclohexano-18-crown-6 (DtBuCH18C6) and benzo-18-crown-6 (B18C6) in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([C4mim][NTf2]) ionic liquid after irradiation were performed for the first time. It was found that the yield for radiolytic destruction of DCH18C6 and DtBuCH18C6 was less than that for B18C6. The main radiolytic products were identified as substituted crown ethers formed between crown ether and active radicals such as methyl, trifluoromethyl, butyl, and [C4mim]˙ radicals generated during the irradiation of the crown ether-[C4mim][NTf2] system. The radiation effect on the Sr(2+) partitioning of the crown ether-[C4mim][NTf2] system shows further that DCH18C6-[C4mim][NTf2] and DtBuCH18C6-[C4mim][NTf2] still have good extractability for Sr(2+) after irradiation. The extraction ability of DCH18C6-[C4mim][NTf2] and DtBuCH18C6-[C4mim][NTf2] system for Sr(2+) decreased by 14.4% and 18.2% even at 500 kGy, respectively.

Separation of samarium and europium by solvent extraction with an undiluted quaternary ammonium ionic liquid: towards high-purity medical samarium-153

“…Moreover, DCH18C6 already proved to be signicantly radiation-resistant. [38][39][40][41][42] The alkaline extraction capacities of the ionic liquid itself were used in a second approach, without the addition of any extractants. Trivalent lanthanide ions have the advantage of being able to form anionic complexes with bidentate nitrate ligands, whereas divalent metal ions are unable to form these species.…”

Evidence for Indirect Action of Ionizing Radiation in 18-Crown-6 Complexes with Halogenous Salts of Strontium: Simulation of Radiation-Induced Transformations in Ionic Liquid/Crown Ether Compositions

“…As discussed above, the extractants based of RTIL/CE solutions have demonstrated enhanced radiation sensitivity in a number of cases. − It is one of the serious drawbacks for a practical applicability of these compositions in nuclear reprocessing. In our opinion, the relatively high degradation of the functional characteristics of RTIL/CE under their irradiation may be partially explained by the effects of indirect action of ionizing radiation on individual components of the system.…”

“…In this situation, the RTIL/CE solutions would expose to ionizing irradiation, and radiation stability of the whole system is one of the key issues for its practical applicability. Although the radiation stability of neat RTIL at least is acceptable, , the multicomponent RTIL/CE compositions have demonstrated a sharp decrease in cation binding ability due to radiation destruction under irradiation. − Up to now, several concepts were developed to explain a sensitivity of the RTIL/CE extractants to ionizing radiation. One of them relies on chemical “blocking” the macrocycle with acidic stable radiolytic products generated from ionic liquid .…”

“…A high radiation destruction of the crown ethers in γ-irradiated RTIL/CE solutions has been alternatively ascribed to covalent addition of radical species produced from anions of RTIL to a macrocycle. 5 Despite the possibility of a contribution from these reactions into the secondary processes of radiolysis, one can expect more efficient interaction of these radical intermediates with RTIL cations.…”

Cesium and Strontium Uptake Utilizing a New Ternary Solid-State Supramolecular Adsorbent under a Framework of Group Partitioning

“…Cs was strongly and selectively recognized by calix[4]­arene-crown-6 families, − while Sr was removed based on the supramolecular recognition agent with some derivatives of crown ethers such as dicyclohexyl-18-crown-6 (DCH18C6) and 4,4′(5′)-di- tert -butyldicyclo­hexano-18-crown-6 (DT). − Some extraction processes such as cesium extraction (CSEX), caustic-side solvent extraction (CSSX), and strontium extraction (SREX) used to remove Sr or Cs were reported. However, research on the simultaneous separation of Cs and Sr which was of significant interest for its great advantages on simple devices and elimination of regenerated liquid waste, was relatively few.…”