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Room-temperature ionic liquids (RTILs) are regarded asgreen solventsdue to their low volatility, low flammability, and thermal stability.RTILs exhibit wide electrochemical windows, making them prime candidatesas media for electrochemically driven reactions such as electro-catalysisand electro-plating for separations applications. Therefore, understandingthe factors determining edges of the electrochemical window, the electrochemicalstability of the RTILs, and the degradation products is crucial toimprove the efficiency and applicability of these systems. We presenthere computational investigations of the electrochemical propertiesof a variety of RTILs covering a wide range of electrochemical windows.We proposed four different approaches with different degrees of approximationand computational cost from gas-phase calculations to full explicitsolvation models. It was found that, whereas the simplest model hassignificant flaws in accuracy, implicit and explicit solvent modelscan be used to reliably predict experimental data. The general trendof electrochemical windows of the RTILs studied is well reproduced,showing that it increases in the order of imidazolium < ammonium< pyrrolidinium < phosphonium giving confidence to the methodologypresented to use it in screening studies of ionic liquids. [ABSTRACT FROM AUTHOR]

In alkaline carbonate solutions both technetium and uraniumexistas anionic species, TcO4–and UO2(CO3)34–, which makesseparating Tc and U from each other more challenging compared to acidicPUREX type solutions where uranium forms neutral or cationic complexes.We tested the batch separation of 99Tc, 238U,and 239Pu from carbonate solutions using anion exchangeresins with different properties, including Purolite A530E, ReillexHPQ, and Dowex Marathon WBA. Overall, the highest Kdvalues for pertechnetate were achieved using the strongbase resins in solutions of the lowest carbonate concentration. Pretreatingthe resins in higher carbonate concentrations before use was shownto increase the Kdvalues for pertechnetate.The measured Kdvalues for uranium generallywere low, resulting in high selectivity for the separation of pertechnetatefrom uranium in carbonate solutions. [ABSTRACT FROM AUTHOR]

In alkaline carbonate solutions, hydrogen peroxide can selectively replace one of the carbonate ligands in UO2(CO3)34- to form the ternary mixed U(VI) peroxo-carbonato species UO2(O2)(CO3)24-. Orange rectangular plates of K4UO2(CO3)2(O2)] · H2O were isolated and characterized by single crystal X-ray diffraction studies. Crystallographic data: monoclinic, space group P21/n, a = 6.9670(14) Å, b = 9.2158(10) Å, c = 18.052(4) Å, Z = 4. Spectrophotometric titrations with H2O2 were performed in 0.5 M K2CO3, with UO2(O2)(CO3)24- concentrations ranging from 0.1 to 0.55 mM. The molar absorptivities (M-1 cm-1) for UO2(CO3)34- and UO2(O2)(CO3)24- were determined to be 23.3 ± 0.3 at 448.5 nm and 1022.7 ± 19.0 at 347.5 nm, respectively. Stoichiometric analyses coupled with spectroscopic comparisons between solution and solid state indicate that the stable solution species is UO2(O2)(CO3)24-, which has an apparent formation constant of log K′ = 4.70 ± 0.02 relative to the tris-carbonato complex. [ABSTRACT FROM AUTHOR]

Task-specific ionic liquids (TSILs) present an opportunity to replace traditional organic solvents for metal dissolution or separation. To date, a thorough investigation of the physical properties of biphask TSIL-- H2O systems and the effects of metal loading is lacking. In this work, the change in the liquid--liquid equilibrium of [HBet][Tf2N]-H2O upon the addition of Nd(IIl) is investigated by doud-point measurements. The addition of Nd(III), drops the upper critical solution temperature by over 20 °C. Further investigation of the [HBet][Tf2N]- Nd(III) system led to the formation of single crystals of [Nd,(H2O)8(µ2-Bet)2(µ3-Bet)2][(Cl)2(Tf2N)4] from the TSIL phase. [ABSTRACT FROM AUTHOR]