Ionic Liquid Radiation Chemistry

Wishart, James F.

doi:10.1002/9781118839706.ch10

Cited by 10 publications

(9 citation statements)

References 49 publications

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“…Before radiolysis kinetics studies were performed using a given batch of C 4 mpyrr NTf 2 , the lifetime of the solvated electron in Ar-purged C 4 mpyrr NTf 2 was measured by transient absorption at 900 nm. If the electron lifetime was on the order of 1 μs or longer, the batch of IL was deemed sufficiently free of adventitious scavengers to be used for kinetics measurements . In order to obtain the rate constant for the reaction of solvated electrons with TMDGA, solutions of 0, 65, 115, 203, and 247 mM TMDGA in C 4 mpyrr NTf 2 were prepared in 1 cm Suprasil self-masking semi-micro spectrophotometer cuvettes capped with silicone septa and purged with argon.…”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

“…If the electron lifetime was on the order of 1 μs or longer, the batch of IL was deemed sufficiently free of adventitious scavengers to be used for kinetics measurements. 34 In order to obtain the rate constant for the reaction of solvated electrons with TMDGA, solutions of 0, 65, 115, 203, and 247 mM TMDGA in C 4 mpyrr NTf 2 were prepared in 1 cm Suprasil self-masking semi-micro spectrophotometer cuvettes capped with silicone septa and purged with argon. The experimental data collection system were described in a previous publication.…”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

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Radiation-Induced Fragmentation of Diamide Extraction Agents in Ionic Liquid Diluents

et al. 2012

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N,N,N',N'-Tetraalkyldiglycolamides are extracting agents that are used for liquid-liquid extraction of trivalent metal ions in wet processing of spent nuclear fuel. This application places such agents in contact with the decaying radionuclides, causing radiolysis of the agent in the organic diluent. Recent research seeks to replace common molecular diluents (such as n-dodecane) with hydrophobic room-temperature ionic liquids (ILs), which have superior solvation properties. In alkane diluents, rapid radiolytic deterioration of diglycolamide agents can be inhibited by addition of an aromatic cosolvent that scavenges highly reactive alkane radical cations before these oxidize the extracting agent. Do aromatic ILs exhibit a similar radioprotective effect? To answer this question, we used electron paramagnetic resonance spectroscopy to study the fragmentation pathways in radiolysis of neat diglycolamides, their model compounds, and their solutions in the ILs. Our study indicates that aromatic ILs do not protect these types of solutes from extensive radiolytic damage. Previous research indicated a similar lack of protection for crown ethers, whereas the ILs readily protected di- and trialkyl phosphates (another large class of metal-extracting agents). Our analysis of these unanticipated failures suggests that new types of organic anions are required in order to formulate ILs capable of radioprotection for these classes of solutes. This study is a cautionary tale of the fallacy of analogical thinking when applied to an entirely new and insufficiently understood class of chemical materials.

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Section: Experimental and Computational Methodsmentioning

confidence: 99%

Section: Experimental and Computational Methodsmentioning

confidence: 99%

Radiation-Induced Fragmentation of Diamide Extraction Agents in Ionic Liquid Diluents

et al. 2012

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“…Identical concerns about excessive solvent viscosity exist for the use of hydrophobic ILs as diluents for liquid–liquid extraction in nuclear separations . Radiation stability of such diluents is important, − and radiation-induced redox reactions are frequently similar to the redox reactions occurring on the electrode(s) during electrolyte breakdown. ,− As spectroscopic observations of reactive intermediates are more amenable in a bulk of the material, radiolysis provides a convenient method for probing mechanisms of electrolyte breakdown. − …”

Section: Introductionmentioning

confidence: 99%

Why Bis(fluorosulfonyl)imide Is a “Magic Anion” for Electrochemistry

et al. 2014

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Ionic liquids consisting of bis(fluorosulfonyl)imide (FSI − ) anion show promise as electrolytes for Li-ion-based electric storage devices, as they exhibit relatively low viscosity, high chemical stability, and form robust solid−electrolyte interphase (SEI) protecting liquid electrolyte from further breakdown on the electrode. These ionic liquids have been reported to inhibit dendrite formation on lithium metal and lithiated graphite electrodes, which also relates to the unusual SEI properties. In this study, we examine the chemistry aspects that may account for this behavior. Radiolysis was used to induce redox reactions of FSI − anions in model systems, and matrix isolation electron paramagnetic resonance was used to identify radical (ion) intermediates generated in these reactions. Our results suggest that qualitative differences between such ionic liquid electrolytes versus common carbonate electrolytes reflect ease of mineralization of the reduced anion without the concurrent generation of organic radicals and/or elimination of gaseous products in side reactions of the corresponding radical intermediates.

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“…The desired IL property that is examined in this study is radiation stability. − This property is important in a diluent that is used for processing of spent nuclear fuel, as the cumulative dose per life cycle of the solvent used in liquid–liquid extractions of radionuclide cations can exceed 100 Mrad (100 rad = 1 J/kg). Ionizing radiation excites the constituent ions, causing them to fragment and/or ionize.…”

Section: Introductionmentioning

confidence: 99%

The AHA Moment: Assessment of the Redox Stability of Ionic Liquids Based on Aromatic Heterocyclic Anions (AHAs) for Nuclear Separations and Electric Energy Storage

Shkrob

Marin

2015

J. Phys. Chem. B

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Because of their extended conjugated bond network, aromatic compounds generally have higher redox stability than less saturated compounds. We conjectured that ionic liquids (ILs) consisting of aromatic heterocyclic anions (AHAs) may exhibit improved radiation and electrochemical stability. Such properties are important in applications of these ILs as diluents in radionuclide separations and electrolytes in the electric energy storage devices. In this study, we systematically examine the redox chemistry of the AHAs. Three classes of these anions have been studied: (i) simple 5-atom ring AHAs, such as the pyrazolide and triazolides, (ii) AHAs containing an adjacent benzene ring, and (iii) AHAs containing electron-withdrawing groups that were introduced to reduce their basicity and interaction with metal ions. It is shown that fragmentation in the reduced and oxidized states of these AHAs does not generally occur, and the two main products, respectively, are the H atom adduct and the imidyl radical. The latter species occurs either as an N σ-radical or as an N π-radical, depending on the length of the N-N bond, and the state that is stabilized in the solid matrix is frequently different from that having the lowest energy in the gas phase. In some instances, the formation of the sandwich π-stack dimer radical anions has been observed. For trifluoromethylated anions, H adduct formation did not occur; instead, there was facile loss of fluoride from their fluorinated groups. The latter can be problematic in nuclear separations, but beneficial in batteries. Overall, our study suggests that AHA-based ILs are viable candidates for use as radiation-exposed diluents and electrolytes.

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Ionic Liquid Radiation Chemistry

Cited by 10 publications

References 49 publications

Radiation-Induced Fragmentation of Diamide Extraction Agents in Ionic Liquid Diluents

Radiation-Induced Fragmentation of Diamide Extraction Agents in Ionic Liquid Diluents

Why Bis(fluorosulfonyl)imide Is a “Magic Anion” for Electrochemistry

The AHA Moment: Assessment of the Redox Stability of Ionic Liquids Based on Aromatic Heterocyclic Anions (AHAs) for Nuclear Separations and Electric Energy Storage

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