Anion effect on radiochemical stability of room-temperature ionic liquids under gamma irradiation

Abstract

Radiochemical stability of imidazolium-based ionic liquids constituted of the BuMeIm(+) cation and associated with four commonly used anions (X(-): Tf(2)N(-), TfO(-), PF(6)(-) and BF(4)(-)) has been investigated under gamma irradiation for high irradiation doses (up to 2.0 MGy). The anion effect has been examined by quantifying the radiolytic yields of disappearance for cation and anions and by identifying corresponding radiolysis products with several analytical techniques. On the one hand, a large number of radiolysis products are formed throughout the irradiation in ionic liquid solutions, resulting from reactions of primary generated species of cation and anion by indirect radiolysis. Primary generated species can react together throughout the irradiation by indirect radiolysis to form numerous radiolysis products in small quantities, indicating that several complex degradation pathways are involved for these radiation doses. This degradation pattern has been confirmed by identification of numerous gaseous radiolytic products. On the other hand, quantitative studies show that radiochemical stabilities of ionic liquids are in the same range of values as systems envisioned in nuclear fuel reprocessing with relatively low hydrogen yields. Indeed, this present work emphasizes the suitability of ionic liquids for applications in the nuclear fuel cycle.

Effect of gamma irradiation on gas-ionic liquid and water-ionic liquid interfacial stability

“…Inspection of the products listed above and the related IL structures shows that they are formed by decomposition of one or both of the anionic and cationic moieties of the ILs. Similar results were observed by Le Rouzo et al [14] during c-irradiation of an IL having the same imide anion as we have studied but a different cation. There were no noticeable changes in the gas phase product speciation with increased irradiation time suggesting that the radiolytic decomposition of the ILs reached a steady state quickly with continuous irradiation.…”

“…In the intended application, a water-IL system will be exposed to continuous ionizing radiation that can strongly influence the chemical state of the system and the chemical parameters affecting the separation efficiency of the system. Studies on the effects of radiation on the stability of ILs are rare and have been limited to studies of pure IL phases [11][12][13][14][15][16][17]. These studies, mostly confined to ammoniumbased ILs (AILs), have shown that ILs are relatively radiation resistant, compared to water or organic solvents, because of the smaller probability of 'dry' electrons escaping geminate or recombination reactions before they are solvated [9,15].…”

On continuous, solvent-free synthesis of ionic liquid [BMIM]Br in a microbore tube

“…ILs have intrinsic ionic conductivity at room temperature and thus can offer, unlike molecular solvents, a wide electrochemical window which can be harnessed in several processes [4][5][6]. Also their chemical and physical properties are tunable by selection of suitable cation and anion [7][8][9][10]. Owing to these advantages, ILs find many applications as novel solvents in organic synthesis and separation processes [11][12][13][14][15][16].…”

Electrochemical behaviour of tetrachloro and tetrabromo uranyl complexes in room temperature ionic liquids

“…For these reasons, they are currently considered as ''green'' solvents to replace the traditional solvents, especially the volatile organic compounds, in many fields: organic and inorganic synthesis, catalysis, polymerization and various electrochemical devices [5]. They are also under investigation in the field of nuclear power industry, as recent work has shown their good stability under a, b and c irradiation [5][6][7][8][9]. Indeed, ILs could be involved in some specific steps of separation or purification of actinides in the frame of nuclear fuel reprocessing, especially in electrodeposition processes.…”