Uranium, electrochemistry

Molten salt-based uranium electrochemistry continues to be an important area of research because of the use of pyrochemi-cal processes within the nuclear industry. Previous reviews have covered a large portion of the literature but recent reports have added to the body of knowledge. The recent review by Wdlit etal. on the electrorefining of uranium and plutonium offers comprehensive literature coverage from... 

The electrochemistry of the uranium(lV) and thorium(IV) complexes M(acac)2L (L = Pc, oep dianions) has been studied in benzonitrile solution. In the complexes of both elements, a series of reversible redox processes have been detected, most of which are centred on the macrocyclic rings (Table 21). 

Allen PG, Conradson SD, Wilson MS, Gottesfeld S, Raistrick ID (1993) Real time structural electrochemistry of platinum clusters using dispersive XAFS. Mat Res Soc Symp Proc 307 (Applications of Synchrotron Radiation Techniques to Materials Science) 51-56 Allen PG, Conradson SD, Wilson MS, Gottesfeld S, Raistrick ID, Valerio J, Lovato M (1995b) Direct observation of surface oxide formation and reduction on platinum clusters by time-resolved X-ray absorption spectroscopy. J. Electroanal Chem 384 99-103 Allen PG, Shuh DK, Bucher JJ, Edelstein NM, Palmer CEA, Silva RJ, Nguyen SN, Marquez LN, Hudson EA (1996b) Determinations of uranium structures by EXAFS schoepite and other U(VT) oxide precipitates. Radiochim Acta 75 47-53... 

Baston et al. [60] studied the samples of ionic liquid after the anodization of uranium metal in [EMIMjCl using the U Lm-edge EXAFS to establish both the oxidation state and the speciation of uranium in the ionic liquid. This was part of an ongoing study to replace high-temperature melts, such as LiQ KQ [61], with ionic liquids. Although it was expected that, when anodized, the uranium would be in the +3 oxidation state, electrochemistry showed that the uranium is actually in a mixture of oxidation states. The EXAFS of the solution showed an edge jump at 17166.6 eV, indicating a mixture of uranium(IV) and uranium(VI). The EXAFS data and pseudo-radial distribution functions for the anodized uranium in [EMIMjCl are shown in Eig. 4.1-12. 

Uses Solvent in coatings, inks, electrochemistry, polymer and boron chemistry, physical processes such as gas absorption, extraction, stabilization, industrial prods, such as fuels, lubricants, textiles, pharmaceuticals, pesticides diluent in VC dispersions extractant for uranium ores selective solvent for extraction of gold coupling solvent solvent, carrier, stabilizer in pharmaceuticals Features High-boiling inert... 

Mikheev (1988,1989,1992) has obtained extensive evidence through cocrystallization that almost all the tripositive lanthanide (except for Sm, Eu, Tm and Yb) and actinide ions (U, Np, Pu, Cm, Bk) can be reduced and have (M /M ) in the neighborhood of — 2.5 to — 2.9 V. The lanthanide potentials are not consistent with the experimentally confirmed generalized f electron energetics scheme developed by Nugent (1975). The potentials are not consistent with potentials inferred from pulse-radiolysis studies (Sullivan et al. 1976,1983,1988). If the potentials (M /M ) proposed by Mikheev for uranium, —2.54 V, and plutonium, —2.59 V, at macroscopic concentrations (Mikheev etal. 1991) were correct, phase diagram studies and electrochemistry ih molten salts should have revealed the ions and Pu ", but no evidence other than cocrystallization has been presented. In fact, the crystal chemistry of the reduced uranium halide NaUjCl (Schleid and Meyer 1989) is consistent with ions and metallic electrons. The cocrystallization model (Mikheev and Merts 1990) may not be transferable to aqueous solution and thus Mikheev s (M /M ) potentials are not cited in table 5. 

However, osmium is a very rare resource and osmium oxide volatilize easily. Therefore, it was necessary to develop cheaper catalysts with excellent performances for ammonia synthesis. Since then, Haber identified that uranium is active for ammonia synthesis. However, in 1912, he was appointed as the director of Institute of Physical Chemistry and Electrochemistry in the Kaiser Wilhelm Institute, indicating the end of the research activity of Haber in the field of ammonia synthesis. Since then, Bosch and Mittasch became the principal researchers in BASF to continue the industrialization process for the ammonia synthesis. Bosch was the leader of the whole research group, and Mittasch became the main investigator for the exploration of catalysts. 

Straka, M., Korenko, M., and Lisy, F. (2010) Electrochemistry of uranium in LiF-Bep2 melt. J. Radioanal. Nucl. Chem, 284, 245. 

Kryukova, A.I., Korshunov, LA., Mitrofanova, V.A. et al. (1979) Uranium and rare earth element phosphates in molten alkali chlorides (in Russian), in Physical Chemistry and Electrochemistry Molten and Solid Electrolytes, Part 1, Akad Nauk SSSR Ural skii Nauchnyi Tsentr, Sverdlovsk, pp. 138-139. 

Carbonate complexes analogous to those found for the various oxidation states of uranium are to be expected for other actinides. Their stabilities certainly depend mainly upon the oxidation state and hence do not differ very much from what has been found for the analogous uranium complexes [248]. Maya [272] and Wester and Sullivan [274] determined the Np(vi)/Np(v) and Pu(vi)/Pu(v) potentials respectively in carbonate media. Electrochemistry, equilibria, and kinetics of actinide carbonate complexes have been critically reviewed [271]. 

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