[en] The development method for uranyl ion determination by the optimization of chemical reaction and instrumental parameters is shown. This method is based on preconcentration stage, where in adsorptive accumulation of metallic complex in a static electrode is presented. (author)

[en] The electrochemical reduction of uranyl ion at the dropping mercury electrode and/or mercury microelectrode has been studied in popanediol-1,2-carbonate(PDC) by voltammetric techniques. The position of the peak potentials, the nature of the limiting currents, their dependency on the temperature and on the concentrations, reversibility or irreversibility of the electrode reactions, and influence of phenol are described. The influence of PDC in aqueous solution of uranyl ion was also described. The values of kinetic parameters, viz. transfer coefficient, formalrate constant for the electrode reactions have been determined by Kouteck's method as extended by Meites and Israel. The values of ΔH, ΔG, and ΔS have been calculated. (Author)

[en] Extraction has been studied of uranium(VI) from solutions of sodium trifluor-, trichloro-, and tribromo- acetates and sodium naphthalenesulfonate with chloroform solution of diantipyrylmethane. Conditions of quantitative extraction and composition of the extracted uranium(VI) complex UO₂LX₂ have been determined. Chemical features of the extraction process are discussed

No abstract available

[en] The use of uranium as a nuclear energy source has made it a valuable mineral resource over the past forty years. Processing uranium generally involves leaching the metal as the uranyl ion (UO₂)²⁺ from ore, followed by solvent extraction, precipitation or batch adsorption onto ion exchange-type resins. Uranium reserves exist also in the form of UO₂(CO₃)₃^4- dissolved in seawater, and although these concentrations are very low they represent globally some 4.9 x 10⁹ tons. In the interest of tapping this resource efforts toward developing more efficient and selective means of UO₂²⁺ ion sequestering have been underway for some time. The authors have measured the stability and protonation constants of the different complexes formed in aqueous solution between the UO₂²⁺ ion and the compounds N,N'-dimethylaminomethylenebis(phosphonic acid) (MAMDP) and aminomethylenebis(phosphonic acid) (AMDP). From these data one can evaluate the potential for compounds of this type to be useful as uranyl ion sequestering agents

[en] Published in summary form only

[en] The tetrahydrofuran complex of uranyl nitrate UO₂(NO₃)₂ 2C₄H₈O was prepared and its crystal structure was determined. Cell parameters of a = 9.412 (7) A, b = 12.649 (9) A, C = 7.237 (5) A, β = 117.12 (6), and V = 766.8A were determined. The molecular structure was found to consist of a U atom on a center of symmetry coordinated to eight O atoms. The two uranyl O atoms were found to be perpendicular to the plane of the remaining coordinating O atoms

[en] The highly anisotropic uranyl complexes (with very short U-O distances and very long distances to the ligating atoms in the equatorial plane) are compared with trans-dioxo complexes of 4d²Ru(VI) and 5d²Re(V) and Os(VI). A major difference is the low-lying empty 5f orbitals, and the first excited state is highly oxidizing, and sufficiently long-lived to abstract hydrogen atoms from most organic molecules. It is argued that even the low concentrations of uranyl carbonate present in sea water is excited by solar radiation roughly every 10 minutes. Octahedral U(VI)O₆ in perovskites and UF₆ are also discussed, as well as trans-lawrencium chemistry

[en] The stability constant of the complex of UO₂⁺⁺ ion with N-glycylglycine was determined polarographically. (M.G.B.)

[en] By the application of suitable spectrophotometric methods and pH-metric measurements it has been established that uranyl ion and 3-hydroxyflavone from a [UO₂(C₁₅H₉O₃)]⁺ complex. The concentration stability constant of the complex was determined by Bent-French's (β₁ = 8,59 at pH = 3,5) and Bjerrum's (from 8,68 at pH = 4 to 6,14 at pH = 7) methods. Conditions are given for the spectrophotometric determination of 3-hydroxyflavone by means of the complex. The regression equation is calculated and the accuracy of the method is determined. All investigations were carried out with 80 % ethanolic solutions at room temperature (20 %), the spectrophotometric measurements being performed at a constant pH (3,5) and a constant ionic strength (0,01 M). (Authors)