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Sample records for synthesized uranyl phases

  1. Investigation of uranyl-ion hydrolysis in uranyl pertechnetate and uranyl perchlorates solutions by two-phases potentiometric titration method

    International Nuclear Information System (INIS)

    Volk, V.I.; Belikov, A.D.

    1977-01-01

    The applicability of the method of two-phase potentiometric titration for studying hydrolysis of multi-charge ions has been shown. Hydrolysis of uranyl-ion has been investigated and hydrolysis constants in the solutions of uranyl pertechnetate and perchlorate have been calculated equal to (6.2+-0.15)x10 -5 and (9.25+-0.5)10 -5 , respectively. Infrared spectra of the initial crystallohydrates of uranyl pertechnetate and perchlorate has been analyzed. The data on hydrolysis of an uranyl-ion and IR spectra of crystallohydrates of the investigated salts have revealed the ability of pertechnetate ion to complexing with an uranyl group

  2. Hydrothermal syntheses and characterization of uranyl tungstates with electro-neutral structural units

    Energy Technology Data Exchange (ETDEWEB)

    Balboni, Enrica; Burns, Peter C. [Univ. of Notre Dame, IN (United States). Dept. of Civil and Enviromental Engineering and Earth Sciences; Univ. of Notre Dame, IN (United States). Dept. of Chemistry and Biochemistry

    2015-11-01

    Two uranyl tungstates, (UO{sub 2})(W{sub 2}O{sub 7})(H{sub 2}O){sub 3} (1) and (UO{sub 2}){sub 3}(W{sub 2}O{sub 8})F{sub 2}(H{sub 2}O){sub 3} (2), were synthesized under hydrothermal conditions at 220 C and were structurally, chemically, and spectroscopically characterized. 1 Crystallizes in space group Pbcm, a = 6.673(5) Aa, b = 12.601(11) Aa, c = 11.552 Aa; 2 is in C2/m, a = 13.648(1) Aa, b = 16.852(1) Aa, c = 9.832(1) Aa, β = 125.980(1) {sup circle}. In 1 the U(VI) cations are present as (UO{sub 2}){sup 2+} uranyl ions that are coordinated by five oxygen atoms to give pentagonal bipyramids. These share two edges with two tungstate octahedra and single vertices with four additional octahedra, resulting in a sheet with the iriginite-type anion topology. Only water molecules are located in the interlayer. The structural units of 2 consist of (UO{sub 2}){sup 2+} uranyl oxy-fluoride pentagonal bipyramids present as either [UO{sub 2}F{sub 2}O{sub 3}]{sup -6} or [UO{sub 2}FO{sub 4}]{sup -5}, and strongly distorted tungstate octahedra. The linkage of uranyl pentagonal bipyramids and tungstate octahedra gives a unique sheet anion topology consisting of pentagons, squares and triangles. In 2, the uranyl tungstates sheets are connected into a novel electro-neutral three-dimensional framework through dimers of uranyl pentagonal bipyramids. These dimers connecting the sheets share an edge defined by F anions. 2 is the first example of a uranyl tungstate oxy-fluoride, and 1 and 2 are rare examples of uranyl compounds containing electro-neutral structural units.

  3. Hydrothermal Phase Relations Among Uranyl Minerals at the Nopal I Analog Site

    International Nuclear Information System (INIS)

    Murphy, William M.

    2007-01-01

    Uranyl mineral paragenesis at Nopal I is an analog of spent fuel alteration at Yucca Mountain. Petrographic studies suggest a variety of possible hydrothermal conditions for uranium mineralization at Nopal I. Calculated equilibrium phase relations among uranyl minerals show uranophane stability over a broad range of realistic conditions and indicate that uranyl mineral variety reflects persistent chemical potential heterogeneity. (author)

  4. Np Incorporation into Uranyl Alteration Phases: A Quantum Mechanical Approach

    International Nuclear Information System (INIS)

    L.C. Huller; R.C. Win; U.Ecker

    2006-01-01

    Neptunium is a major contributor to the long-term radioactivity in a geologic repository for spent nuclear fuel (SNF) due to its long half-life (2.1 million years). The mobility of Np may be decreased by incorporation into the U 6+ phases that form during the corrosion of SNF. The ionic radii of Np (0.089nm) and U (0.087nm) are similar, as is their chemistry. Experimental studies have shown Np can be incorporated into uranyl phases at concentrations of ∼ 100 ppm. The low concentration of Np in the uranyl phases complicates experimental detection and presents a significant challenge for determining the incorporation mechanism. Therefore, we have used quantum mechanical calculations to investigate incorporation mechanisms and evaluate the energetics of Np substituting for U. CASTEP, a density functional theory based code that uses plane waves and pseudo-potentials, was used to calculate optimal H positions, relaxed geometry, and energy of different uranyl phases. The incorporation energy for Np in uranyl alteration phases was calculated for studtite, [(UO 2 )O 2 (H 2 O) 2 ](H 2 ) 2 , and boltwoodite, HK(UO 2 )(SiO 4 )* 1.5(H 2 O). Studtite is the rare case of a stable uranyl hydroxyl-peroxide mineral that forms in the presence of H 2 O 2 from the radiolysis of H 2 O. For studtite, two incorporation mechanisms were evaluated: (1) charge-balanced substitution of Np 5+ and H + for one U 6+ , and (2) direct substitution of Np 6+ for U 6+ . For boltwoodite, the H atomic positions prior to Np incorporation were determined, as well as the Np incorporation mechanisms and the corresponding substitution energies. The preferential incorporation of Np into different structure types of U 6+ minerals was also investigated. Quantum mechanical substitution energies have to be derived at Np concentrations higher than the ones found in experiments or expected in a repository. However, the quantum mechanical results are crucial for subsequent empirical force-field and Monte

  5. Structural contributions to the third-law entropy of uranyl phases

    International Nuclear Information System (INIS)

    Chen, F.; Ewing, R.C.

    1999-01-01

    Entropies that are used in geochemical calculations are usually based on calorimetric measurements. However, because of the contributions of neglected residual entropies which cannot be determined by calorimetric measurements, the true third-law entropies for many phases may be quite different from those derived from thermal data. The residual entropies are caused by site-mixing, structural disorder and magnetic spin disorder and may result in a considerable contribution to the third-law entropy of solid phases. Magnetic spin-configurational entropy is not expected to be significant in uranyl phases. However, because most uranyl phases are based on sheet or chain structures and usually contain several molecular water groups, site-mixing, vacancies, as well as disorder in the orientation of hydrogen bonds and the polar H 2 O molecules may occur. Calculations of the ideal site-mixing configurational entropy for some uranyl phases indicate that the residual contributions that arise from substitution and vacancies to the third-law entropies of uranyl phases may be large. A brief examination of the crystal chemistry of water molecules in uranyl phases suggests that considerable residual entropy may be caused by the disorder of hydrogen bonds associated with interstitial H 2 O groups

  6. Solid phase syntheses of oligoureas

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, K.; Linthicum, D.S.; Russell, D.H.; Shin, H.; Shitangkoon, A.; Totani, R.; Zhang, A.J.; Ibarzo, J. [Texas A& M Univ., College Station, TX (United States)

    1997-02-19

    Isocyanates 7 were formed from monoprotected diamines 3 or 6, which in turn can be easily prepared from commercially available N-BOC- or N-FMOC-protected amino acid derivatives. Isocyanates 7, formed in situ, could be coupled directly to a solid support functionalized with amine groups or to amino acids anchored on resins using CH{sub 2}Cl{sub 2} as solvent and an 11 h coupling time at 25 {degree}C. Such couplings afforded peptidomimetics with an N-phthaloyl group at the N-terminus. The optimal conditions identified for removal of the N-phthaloyl group were to use 60% hydrazine in DMF for 1-3 h. Several sequences of amino acids coupled to ureas (`peptidic ureas`) and of sequential urea units (`oligoureas`) were prepared via solid phase syntheses and isolated by HPLC. Partition coefficients were measured for two of these peptidomimetics, and their water solubilities were found to be similar to the corresponding peptides. A small library of 160 analogues of the YGGFL-amide sequence was prepared via Houghten`s tea bag methodology. This library was tested for binding to the anti-{beta}-endorphin monoclonal antibody. Overall, this paper describes methodology for solid phase syntheses of oligourea derivatives with side chains corresponding to some of the protein amino acids. The chemistry involved is ideal for high-throughput syntheses and screening operations. 51 refs., 3 figs., 2 tabs.

  7. Re-evaluating neptunium in uranyl phases derived from corroded spent fuel

    International Nuclear Information System (INIS)

    Fortner, J. A.; Finch, R. J.; Kropf, A. J.; Cunnane, J. C.; Chemical Engineering

    2004-01-01

    Interest in mechanisms that may control radioelement release from corroded commercial spent nuclear fuel (CSNF) has been heightened by the selection of the Yucca Mountain site in Nevada as the repository for high-level nuclear waste in the United States. Neptunium is an important radionuclide in repository models owing to its relatively long half-life and its high aqueous mobility as neptunyl [Np(V)O+2]. The possibility of neptunium sequestration into uranyl alteration phases produced by corroding CSNF would suggest-a process for lowering neptunium concentration and subsequent migration from a geologic repository. However, there remains little experimental evidence that uranyl compounds will, in fact, serve as long-term host phases for the retention of neptunium under conditions expected in a deep geologic repository. To directly explore this possibility, we examined specimens of uranyl alteration phases derived from humid-air-corroded CSNF by X-ray absorption spectroscopy to better determine neptunium uptake in these phases. Although neptunium fluorescence was readily observed from as-received CSNF, it was not observed from the uranyl alteration rind. We establish upper limits for neptunium incorporation into CSNF alteration phases that are significantly below previously reported concentrations obtained by using electron energy loss spectroscopy (EELS). We attribute the discrepancy to a plural-scattering event that creates a spurious EELS peak at the neptunium-MV energy

  8. Formation of the second organic phase during uranyl nitrate extraction from aqueous solution by 30% tributylphosphate solution in paraffin

    International Nuclear Information System (INIS)

    Yhrkin, V.G.

    1996-01-01

    For extraction systems aqueous solution of uranyl nitrate-30% solution of tributylphosphate in individual paraffins from C 13 to C 17 the influence of the second organic phase of uranyl nitrate concentration in aqueous and organic phases, the length of hydrocarbon chain of paraffin hydrocarbon and temperature from 25 to 50 deg C on formation conditions has been defected. A special method of achieving the conditions of organic phase stratification from three-phase region, involving definition of equilibrium phases composition by density and refractive index, has been elaborated for more precise definition of organic phase homogeneity region. It has been revealed that without addition of nitric acid to uranyl nitrate solution the organic phase homogeneity limits can be achieved solely on paraffins C 15 , C 16 and C 17 and only under conditions similar to equeous phase saturation in terms of uranyl nitrate. 16 refs., 2 figs

  9. Infrared spectra of volatile adduct of uranyl pivaloyltrifluoroacetonate with hexamethylphosphorotriamide

    International Nuclear Information System (INIS)

    Bukhmarina, V.N.; Dushin, R.B.; Sidorenko, G.V.; Suglobov, D.N.

    1983-01-01

    Adduct of uranyl pivaloyltrifluoroacetonate with hexamethylphosphortriamide (1), sublimated without decomposition and characterized by a high thermal stability, has been synthesized, as well as adducts of uranyl dipivaloylmethanate with hexamethylphosphortriamide (2) and dimethyl sulfoxide (3), sublimated with partial dissociation. IR spectra of crystalline adducts 1-3, their solutions in benzene; gaseous and matrix-isolated adduct 1 have been measured. It is shown that in gaseous phase 1 exists practically completely in non-dissociated form. It is detected that uranyl group in crystalline 1 and 2 and in matrix-isolated 1 in contrast to crystalline 3 and previously studied adducts of uranyl β-diketonates has an asymmetric structure. Strength constants of uranyl group in crystalline 1-3 and matrix-isolated 1 are determined

  10. Oxo-exchange of gas-phase uranyl, neptunyl, and plutonyl with water and methanol.

    Science.gov (United States)

    Lucena, Ana F; Odoh, Samuel O; Zhao, Jing; Marçalo, Joaquim; Schreckenbach, Georg; Gibson, John K

    2014-02-17

    A challenge in actinide chemistry is activation of the strong bonds in the actinyl ions, AnO2(+) and AnO2(2+), where An = U, Np, or Pu. Actinyl activation in oxo-exchange with water in solution is well established, but the exchange mechanisms are unknown. Gas-phase actinyl oxo-exchange is a means to probe these processes in detail for simple systems, which are amenable to computational modeling. Gas-phase exchange reactions of UO2(+), NpO2(+), PuO2(+), and UO2(2+) with water and methanol were studied by experiment and density functional theory (DFT); reported for the first time are experimental results for UO2(2+) and for methanol exchange, as well as exchange rate constants. Key findings are faster exchange of UO2(2+) versus UO2(+) and faster exchange with methanol versus water; faster exchange of UO2(+) versus PuO2(+) was quantified. Computed potential energy profiles (PEPs) are in accord with the observed kinetics, validating the utility of DFT to model these exchange processes. The seemingly enigmatic result of faster exchange for uranyl, which has the strongest oxo-bonds, may reflect reduced covalency in uranyl as compared with plutonyl.

  11. The gas-phase bis-uranyl nitrate complex ((UO2)2(NO3)5)-: infrared spectrum and structure

    International Nuclear Information System (INIS)

    Groenewold, G.S.; van Stipdonk, Michael J.; Oomens, Jos; De Jong, Wibe A.; McIlwain, Michael E.

    2011-01-01

    The infrared spectrum of the bis-uranyl nitrate complex ((UO 2 ) 2 (NO 3 ) 5 ) - was measured in the gas phase using multiple photon dissociation (IRMPD). Intense absorptions corresponding to the nitrate symmetric and asymmetric vibrations, and the uranyl asymmetric vibration were observed. The nitrate v 3 vibrations indicate the presence of nitrate in a bridging configuration bound to both uranyl cations, and probably two distinct pendant nitrates in the complex. The coordination environment of the nitrate ligands and the uranyl cations were compared to those in the mono-uranyl complex. Overall, the uranyl cation is more loosely coordinated in the bis-uranyl complex ((UO 2 ) 2 (NO 3 ) 5 ) - compared to the mono-complex (UO 2 (NO 3 ) 3 ) - , as indicated by a higher O-U-O asymmetric stretching (v 3 ) frequency. However, the pendant nitrate ligands are more strongly bound in the bis-complex than they are in the mono-uranyl complex, as indicated by the v 3 frequencies of the pendant nitrate, which are split into nitrosyl and O-N-O vibrations as a result of bidentate coordination. These phenomena are consistent with lower electron density donation per uranyl by the nitrate bridging two uranyl centers compared to that of a pendant nitrate in the mono-uranyl complex. The lowest energy structure predicted by density functional theory (B3LYP functional) calculations was one in which the two uranyl molecules bridged by a single nitrate coordinated in a bis-bidentate fashion. Each uranyl molecule was coordinated by two pendant nitrate ligands. The corresponding vibrational spectrum was in excellent agreement with the IRMPD measurement, confirming the structural assignment.

  12. The gas-phase bis-uranyl nitrate complex ((UO2)2(NO3)5)-: infrared spectrum and structure

    International Nuclear Information System (INIS)

    Groenewold, Gary S.; van Stipdonk, Michael J.; Oomens, Jos; de Jong, Wibe; McIlwain, Michael E.

    2011-01-01

    The infrared spectrum of the bis-uranyl nitrate complex ((UO 2 ) 2 (NO 3 ) 5 ) - was measured in the gas phase using multiple photon dissociation (IRMPD). Intense absorptions corresponding to the nitrate symmetric and asymmetric vibrations, and the uranyl asymmetric vibration were observed. The nitrate nu3 vibrations indicate the presence of nitrate in a bridging configuration bound to both uranyl cations, and probably two distinct pendant nitrates in the complex. The coordination environment of the nitrate ligands and the uranyl cations were compared to those in the mono-uranyl complex. Overall, the uranyl cation is more loosely coordinated in the bis-uranyl complex ((UO 2 ) 2 (NO 3 ) 5 ) - compared to the mono-complex (UO 2 (NO 3 ) 3 ) - , as indicated by a higher O-U-O asymmetric stretching (nu3) frequency. However, the pendant nitrate ligands are more strongly bound in the bis-complex than they are in the mono-uranyl complex, as indicated by the ν 3 frequencies of the pendant nitrate, which are split into nitrosyl and O-N-O vibrations as a result of bidentate coordination. These phenomena are consistent with lower electron density donation per uranyl by the nitrate bridging two uranyl centers compared to that of a pendant nitrate in the mono-uranyl complex. The structure was calculated using density functional theory (B3LYP functional), which produced a structure in which the two uranyl molecules bridged by a single nitrate coordinated in a bis-bidentate fashion. Each uranyl molecule was coordinated by two pendant nitrate ligands. The corresponding vibrational spectrum was in excellent agreement with the IRMPD measurement, confirming the structural assignment.

  13. Syntheses, structures, and IR spectroscopic characterization of new uranyl sulfate/selenate 1D-chain, 2D-sheet and 3D-framework

    Energy Technology Data Exchange (ETDEWEB)

    Ling Jie; Sigmon, Ginger E.; Ward, Matthew; Roback, Nancy; Burns, Peter C. [Dept. of Civil Engineering and Geological Science, Univ. of Notre Dame, IN (United States)

    2010-07-01

    Three uranyl sulfates, (C{sub 6}H{sub 20}N{sub 4})[(UO{sub 2}){sub 2} . (SO{sub 4}){sub 4}(H{sub 2}O){sub 2}](H{sub 2}O){sub 6} (TETAUS), (C{sub 15}H{sub 14}N{sub 3})[(UO{sub 2}) . (SO{sub 4}){sub 2}](NO{sub 3})(H{sub 2}O){sub 2} (TPUS), and K{sub 2}[(UO{sub 2})(SO{sub 4}){sub 2}(H{sub 2}O)] . H{sub 2}O (KUS), and two uranyl selenates, K(H{sub 3}O)[(UO{sub 2}){sub 2} . (SeO{sub 4}){sub 3}(H{sub 2}O)](H{sub 2}O){sub 6} (KUSe) and (H{sub 3}O){sub 2}[(UO{sub 2}){sub 2}(SeO{sub 4}){sub 3} . (H{sub 2}O)] (USe), were synthesized by slow evaporation of aqueous solutions at room temperature. TETAUS crystallizes in space group P anti 1, a = 6.7186(5) A, b = 9.2625(7) A, c = 13.1078(9) A, {alpha} = 72.337(2) , {beta} = 89.198(2) , {gamma} = 70.037(1) , V = 726.89(9) A{sup 3}, Z = 1. TPUS is triclinic, P anti 1, a = 6.9732(7) A, b = 13.569(1) A, c = 13.641(1) A, {alpha} = 111.809(2) , {beta} = 102.386(2) , {gamma} = 93.833(2) , V = 1150.0(2) A{sup 3}, Z = 2. KUS is orthorhombic, Cmca, a = 12.171(2) A, b = 16.689(3) A, c = 10.997(2) A, V = 2233.8(6) A{sup 3}, Z = 8. These uranyl sulfates are built from infinite one-dimensional uranyl sulfate chains with different topologies. KUSe is monoclinic, P2{sub 1}/n, a = 14.715(1) A, b = 10.1557(7) A, c = 15.833(1) A, {beta} = 114.415(1) , V = 2154.5(3) A{sup 3}, Z = 4. Its structure is based on a two-dimensional uranyl selenate sheet. USe crystallizes in space group P2{sub 1}/c, a = 10.6124(2) A, b = 14.7717(3) A, c = 13.7139(3) A, {beta} = 96.989(1) , V = 2133.86(8) A{sup 3}, Z = 4, with a complex three-dimensional uranyl selenate framework containing channels extending in three directions. (orig.)

  14. Synthesizing lattice structures in phase space

    International Nuclear Information System (INIS)

    Guo, Lingzhen; Marthaler, Michael

    2016-01-01

    In one dimensional systems, it is possible to create periodic structures in phase space through driving, which is called phase space crystals (Guo et al 2013 Phys. Rev. Lett. 111 205303). This is possible even if for particles trapped in a potential without periodicity. In this paper we discuss ultracold atoms in a driven optical lattice, which is a realization of such a phase space crystals. The corresponding lattice structure in phase space is complex and contains rich physics. A phase space lattice differs fundamentally from a lattice in real space, because its coordinate system, i.e., phase space, has a noncommutative geometry, which naturally provides an artificial gauge (magnetic) field. We study the behavior of the quasienergy band structure and investigate the dissipative dynamics. Synthesizing lattice structures in phase space provides a new platform to simulate the condensed matter phenomena and study the intriguing phenomena of driven systems far away from equilibrium. (paper)

  15. Spherical agarose-coated magnetic nanoparticles functionalized with a new salen for magnetic solid-phase extraction of uranyl ion

    International Nuclear Information System (INIS)

    Serenjeh, Fariba Nazari; Hashemi, Payman; Ghiasvand, Ali Reza; Naeimi, Hossein; Zakerzadeh, Elham

    2016-01-01

    The authors describe a method for magnetic solid phase extraction of uranyl ions from water samples. It is based on the use of spherical agarose-coated magnetic nanoparticles along with magnetic field agitation. The salen type Schiff base N,N’-bis(4-hydroxysalicylidene)-1,2-phenylenediamine was synthesized from resorcinol in two steps and characterized by infrared and nucleic magnetic resonance spectroscopies. The particles were then activated by an epichlorohydrin method and functionalized with the Schiff base which acts as a selective ligand for the extraction of UO 2 (II). Following preconcentration and elution with HCl, the ions were quantified by spectrophotometry using Arsenazo III as the indicator. The effects of pH value, ionic strength and amount of the adsorbent on the extraction of UO 2 (II) were optimized by a multivariate central composite design method. Six replicate analyses under optimized conditions resulted in a recovery of 96.6 % with a relative standard deviation of 3.4 % for UO 2 (II). The detection limit of the method (at a signal-to-noise ratio of 3σ) is 10 μg L -1 . The method was successfully applied to the determination of UO 2 (II) in spiked water samples. (author)

  16. Synthesis of phosphorylated calix[4]arene derivatives for the design of solid phases immobilizing uranyl cations

    International Nuclear Information System (INIS)

    Maroun, E.B.; Hagege, A.; Asfari, Z.; Basset, CH.; Quemeneur, E.; Vidaud, C.

    2009-01-01

    With the aim of developing supports for uranyl cations immobilisation, new 1, 3-alternate calix[4]arenes bearing both phosphonic acid functions as chelating sites and N-succinimide-4-oxa-butyrate as the anchoring arm were synthesised in good yields. The coupling of such calixarenes to a gel was performed and a successful immobilisation of uranyl cations was obtained. (authors)

  17. Synthesis of phosphorylated calix[4]arene derivatives for the design of solid phases immobilizing uranyl cations

    Energy Technology Data Exchange (ETDEWEB)

    Maroun, E.B.; Hagege, A.; Asfari, Z. [Laboratoire de Chimie Analytique et Minerale, UMR 7178 ULP/CNRS/IN2P3 LC4, ECPM, Strasbourg Cedex (France); Basset, CH.; Quemeneur, E.; Vidaud, C. [CEA IBEB, SBTN, Centre de Marcoule, Bagnols-sur-Ceze (France)

    2009-07-01

    With the aim of developing supports for uranyl cations immobilisation, new 1, 3-alternate calix[4]arenes bearing both phosphonic acid functions as chelating sites and N-succinimide-4-oxa-butyrate as the anchoring arm were synthesised in good yields. The coupling of such calixarenes to a gel was performed and a successful immobilisation of uranyl cations was obtained. (authors)

  18. Thermochemical investigations on uranyl phosphates and arsenates

    International Nuclear Information System (INIS)

    Barten, H.

    1986-11-01

    The results are described of a study of the thermochemical stability of anhydrous uranyl phosphates and arsenates. A number of aspects of chemical technological importance are indicated in detail. The synthesized anhydrous uranyl phosphates and arsenates were very hygroscopic, so that experiments on these compounds had to be carried out under moisture-free conditions. Further characterisation of these compounds are given, including a study of their thermal stabilities and phase relations. The uranyl phosphates reduced reversibly at temperatures of the order of 1100 to 1600 0 C. This makes it possible to express their relative stabilities quantitatively, in terms of the oxygen pressures of the reduction reactions. The thermal decomposition of uranyl arsenates did not occur by reduction, as for the phosphates, but by giving off arsenic oxide vapour. The results of measurements of enthalpies of solution led to the determination of the enthalpies of formation, heat capacity and the standard entropies of the uranyl arsenates. The thermochemical functions at high-temperatures could consequently be calculated. Attention is paid to the possible formation of uranium arsenates, whose uranium has a valency lower than six, hitherto not reported in literature. It was not possible to prepare arsenates of tetravalent uranium. However, three new compounds were observed, one of these, UAsO 5 , was studied in some detail. (Auth.)

  19. Syntheses and crystal structures of two novel alkaline uranyl chromates A2(UO2)(CrO4)2 (A=Rb, Cs) with bidentate coordination mode of uranyl ions by chromate anions

    International Nuclear Information System (INIS)

    Siidra, Oleg I.; Nazarchuk, Evgeny V.; Krivovichev, Sergey V.

    2012-01-01

    Single crystals of Cs 2 (UO 2 )(CrO 4 ) 2 and Rb 2 (UO 2 )(CrO 4 ) 2 were prepared by solid state reactions. The structures are based upon the [(UO 2 )(CrO 4 ) 2 ] 2− chains. Within the chains, UrO 5 pentagonal bipyramids (Ur=uranyl) form Ur 2 O 8 dimers, which are linked via CrO 4 tetrahedra into one-dimensional chains. The CrO 4 tetrahedra coordinate uranyl ions in both mono- and bidentate fashion, which is unusual for uranyl chromates. The bidentate coordination has a strong influence upon geometrical parameters of both U and Cr coordination polyhedra. The conformation of the chains in 1 and 2 is different due to the different size of the Cs + and Rb + cations. - Graphical abstract: Uranyl chromate chain with monodentate and bidentate coordination mode of uranyl cations by CrO 4 tetrahedra in Cs 2 (UO 2 )(CrO 4 ) 2 . Highlights: ► Single crystals of novel uranyl chromates were prepared by solid state reactions. ► The CrO 4 tetrahedra coordinate uranyl ions in both mono- and bidentate fashion. ►The bidentate coordination has a strong influence upon geometrical parameters.

  20. Mass-spectrometric study of volatile uranyl β-diketonates and their adducts

    International Nuclear Information System (INIS)

    Adamov, V.M.; Belyaev, B.N.; Berezinskij, S.O.; Sidorenko, G.V.; Suglobov, D.N.

    1985-01-01

    The mass spectra of a number of uranyl β-diketonates containing methyl, trifluoromethyl and tert-butyl substituents in β-diketonate anion, and their adducts are measured. The form of the unsolvated β-diketonates and their adducts in gas phase is studied. The ways of fragmentation of uranyl β-diketonates and their adducts are investigated. The data concerning the thermal and chemical side reactions proceeding with uranyl β-diketonates and their addicts in an ion source are obtained. The mass spectra of the samples of neptunyl and plutonyl β-diketonate adducts synthesized for the first time are measured

  1. Phase Transformation of Hydrothermally Synthesized Nanoparticle ...

    African Journals Online (AJOL)

    Mild hydrothermal hydrolysis of TiCl4 produces nanorods of the rutile phase of titanium dioxide in high yield, while in the presence of organic acids (citric, acetic, D-tartaric and benzoic acids) anatase is the only product. The effect of these organic acids on the products of the hydrolysis reaction as well as the reaction kinetics ...

  2. EXTRACTION OF URANYL NITRATE FROM AQUEOUS SOLUTIONS

    Science.gov (United States)

    Furman, N.H.; Mundy, R.J.

    1957-12-10

    An improvement in the process is described for extracting aqueous uranyl nitrate solutions with an organic solvent such as ether. It has been found that the organic phase will extract a larger quantity of uranyl nitrate if the aqueous phase contains in addition to the uranyl nitrate, a quantity of some other soluble nitrate to act as a salting out agent. Mentioned as suitable are the nitrates of lithium, calcium, zinc, bivalent copper, and trivalent iron.

  3. Tritium distribution ratios between the 30 % tributyl phosphate(TBP)-normal dodecane(nDD) organic phase and uranyl nitrate-nitric acid aqueous phase

    International Nuclear Information System (INIS)

    Fujine, Sachio; Uchiyama, Gunzou; Sugikawa, Susumu; Maeda, Mitsuru; Tsujino, Takeshi.

    1989-10-01

    Tritium distribution ratios between the organic and aqueous phases were measured for the system of 30 % tributyl phosphate(TBP)-normal dodecane(nDD)/uranyl nitrate-nitric acid water. It was confirmed that tritium is extracted by TBP into the organic phase in both chemical forms of tritiated water (HTO) and tritiated nitric acid (TNO 3 ). The value of tritium distribution ratio ranged from 0.002 to 0.005 for the conditions of 0-6 mol/L nitric acid, 0.5-800 mCi/L tritium in aqueous phase, and 0-125 g-U/L uranium in organic phase. Isotopic distribution coefficient of tritium between the organic and aqueous phases was observed to be about 0.95. (author)

  4. Chemical phase analysis of seed mediated synthesized anisotropic silver nanoparticles

    International Nuclear Information System (INIS)

    Bharti, Amardeep; Goyal, Navdeep; Singh, Suman; Singla, M. L.

    2015-01-01

    Noble-metal nanoparticles are of great interest because of its broad applications almost in every stream (i.e. biology, chemistry and engineering) due to their unique size/shape dependant properties. In this paper, chemical phase of seed mediated synthesized anisotropic silver nanoparticle (AgNPs) has been investigated via fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These nanaoparticles were synthesized by seed-growth method controlled by urea and dextrose results to highly stable 12-20 nm particle size revealed by zeta potential and transmission electron microscopy (TEM)

  5. Synthesis and complexation properties towards uranyl cation of carboxylic acid derivatives of p-tert-butyl-calix[6]arene; Synthese et proprietes complexantes vis-a-vis de l'ion uranyle de derives carboxyliques du p-tert-butyl-calix[6]arene

    Energy Technology Data Exchange (ETDEWEB)

    Souane, R

    2005-03-15

    In the fuel reprocessing plants radioactive metals, and more particularly, uranium in UO{sub 2}{sup 2+} form in the various installations, have many varied physico-chemical forms and there is a risk of exposure and internal contamination in the nuclear industry. It is necessary to exert a medical control to ensure the protection of the health of the workers. This medical control is done by dosing uranyl cation in the urine of the exposed people. This work forms part of this context. Indeed, we prepared a ligand able to complex the ion uranyl and which is also to be grafted on a solid support. In the family of calixarenes, the calix[6]arenes functionalized by three or four carboxylic functions were selected like chelating molecules of the ion uranyl. The properties of complexation of these calixarenes were studied by potentiometry in methanol, under these conditions balances of protonation and complexation were determined and the constant partners were obtained using the Hyperquad program. We synthesized tri-carboxylic calix[6]arenes comprising of the groupings nitro (NO{sub 2}) in para position of phenol in order to see the influence of a substitution in para position on the complexation. We also synthesized calix[6]arenes tetra-carboxylic in order to show the role of an additional carboxylic acid grouping. The potentiometric study determined thermodynamic parameters of protonation and complexation of carboxylic calix[6]arenes. The results of the complexation highlighted which complex UO{sub 2}L corresponding to the ligand para-tert-butyl-calix[6]arene tetra-acid is more stable than that corresponding to the ligand mono-nitro calix[6]arene tri-acid ({delta}log{beta}110 = 4.3), and than the effect of the groupings nitro in para position has low influence on the complexation of UO{sub 2}{sup 2+}. This makes it possible to consider as possible the grafting of the calix[6]arenes which one knows the behaviour of trapping. To this end we synthesized the ligand 23

  6. Functionalized hydrothermal carbon derived from waste pomelo peel as solid-phase extractant for the removal of uranyl from aqueous solution.

    Science.gov (United States)

    Li, Feize; Tang, Yu; Wang, Huilin; Yang, Jijun; Li, Shoujian; Liu, Jun; Tu, Hong; Liao, Jiali; Yang, Yuanyou; Liu, Ning

    2017-10-01

    To develop a high-performance solid-phase extractant for the separation of uranyl f, pomelo peel, a kind of waste biomass, has been employed as carbon source to prepare carbonaceous matrix through low-temperature hydrothermal carbonization (200 °C, 24 h). After being oxidized by Hummers method, the prepared hydrothermal carbon matrix was functionalized with carboxyl and phenolic hydroxyl groups (1.75 mmol g -1 ). The relevant characterizations and batch studies had demonstrated that the obtained carbon material possessed excellent affinity toward uranyl (436.4 mg g -1 ) and the sorption process was a spontaneous, endothermic and rapid chemisorption. The selective sorption of U(VI) from the simulated nuclear effluent demonstrated that the sorbent displayed a desirable selectivity (56.14% at pH = 4.5) for the U(VI) ions over the other 11 competitive cations from the simulated industrial nuclear effluent. The proposed synthetic strategy in the present work had turned out to be effective and practical, which provides a novel approach to prepare functional materials for the recovery and separation of uranyl or other heavy metals from aqueous environment.

  7. Conducting polymer networks synthesized by photopolymerization-induced phase separation

    Science.gov (United States)

    Yamashita, Yuki; Komori, Kana; Murata, Tasuku; Nakanishi, Hideyuki; Norisuye, Tomohisa; Yamao, Takeshi; Tran-Cong-Miyata, Qui

    2018-03-01

    Polymer mixtures composed of double networks of a polystyrene derivative (PSAF) and poly(methyl methacrylate) (PMMA) were alternatively synthesized by using ultraviolet (UV) and visible (Vis) light. The PSAF networks were generated by UV irradiation to photodimerize the anthracene (A) moieties labeled on the PSAF chains, whereas PMMA networks were produced by photopolymerization of methyl methacrylate (MMA) monomer and the cross-link reaction using ethylene glycol dimethacrylate (EGDMA) under Vis light irradiation. It was found that phase separation process of these networks can be independently induced and promptly controlled by using UV and Vis light. The characteristic length scale distribution of the resulting co-continuous morphology can be well regulated by the UV and Vis light intensity. In order to confirm and utilize the connectivity of the bicontinuous morphology observed by confocal microscopy, a very small amount, 0.1 wt%, of multi-walled carbon nanotubes (MWCNTs) was introduced into the mixture and the current-voltage (I-V) relationship was subsequently examined. Preliminary data show that MWCNTs are preferentially dispersed in the PSAF-rich continuous domains and the whole mixture became electrically conducting, confirming the connectivity of the observed bi-continuous morphology. The experimental data obtained in this study reveal a promising method to design various scaffolds for conducting soft matter taking advantages of photopolymerization-induced phase separation.

  8. Influence of nitric acid on the kinetic of complexation of uranyl nitrate extracted by TBP

    International Nuclear Information System (INIS)

    Pushlenkov, M.F.; Zimenkov, V.V.

    1982-02-01

    The effect of nitric acid on the solvatation rate of uranyl nitrate with tributyl phosphate is studied. In the process of mass transfer, it is shown that nitric acid enables the extraction of uranyl nitrate, therefore its concentration in the organic phase exceeds that in equilibrium solution. Subsequently uranyl nitrate ''displaces'' nitric acid. The presence of the acid in aqueous and organic phases affects in a complicated manner the rate of solvatation of uranyl nitrate with tributyl phosphate [fr

  9. Extraction of uranyl sulfate with primary amine

    International Nuclear Information System (INIS)

    Mrnka, M.; Bizek, V.; Nekovar, P.; Cizevska, S.; Schroetterova, D.

    1984-01-01

    PRIMENE JM-T was used for extraction. Its composition was found to approach the general formula C 21 H 43 NH 2 . It was found that the extraction of uranyl sulfate is lower in case of a higher steady-state concentration of sulfuric acid in the aqueous phase. Extraction is accompanied with coextraction of water. The results obtained showed that uranyl sulfate passes into the organic phase by two mechanisms: extraction with amine sulfate and extraction with free amine. A mathematical description of the process was made based on the obtained results. (E.S.)

  10. Specific capture of uranyl protein targets by metal affinity chromatography

    International Nuclear Information System (INIS)

    Basset, C.; Dedieu, A.; Guerin, P.; Quemeneur, E.; Meyer, D.; Vidaud, C.

    2008-01-01

    To improve general understanding of biochemical mechanisms in the field of uranium toxicology, the identification of protein targets needs to be intensified. Immobilized metal affinity chromatography (IMAC) has been widely developed as a powerful tool for capturing metal binding proteins from biological extracts. However uranyl cations (UO 2 2+ ) have particular physico-chemical characteristics which prevent them from being immobilized on classical metal chelating supports. We report here on the first development of an immobilized uranyl affinity chromatography method, based on the cation-exchange properties of amino-phosphonate groups for uranyl binding. The cation distribution coefficient and loading capacity on the support were determined. Then the stability of the uranyl-bonded phase under our chromatographic conditions was optimized to promote affinity mechanisms. The successful enrichment of uranyl binding proteins from human serum was then proven using proteomic and mass spectral analysis. (authors)

  11. Infrared Spectroscopy of Discrete Uranyl Anion Complexes

    International Nuclear Information System (INIS)

    Groenewold, G. S.; Gianotto, Anita K.; McIIwain, Michael E.; Van Stipdonk, Michael J.; Kullman, Michael; Moore, David T.; Polfer, Nick; Oomens, Jos; Infante, Ivan A.; Visscher, Lucas; Siboulet, Bertrand; De Jong, Wibe A.

    2008-01-01

    The Free-Electron Laser for Infrared Experiments (FELIX) w 1 as used to study the wavelength-resolved multiple photon photodissociation of discrete, gas phase uranyl (UO2 2 2+) complexes containing a single anionic ligand (A), with or without ligated solvent molecules (S). The uranyl antisymmetric and symmetric stretching frequencies were measured for complexes with general formula [UO2A(S)n]+, where A was either hydroxide, methoxide, or acetate; S was water, ammonia, acetone, or acetonitrile; and n = 0-3. The values for the antisymmetric stretching frequency for uranyl ligated with only an anion ([UO2A]+) were as low or lower than measurements for [UO2]2+ ligated with as many as five strong neutral donor ligands, and are comparable to solution phase values. This result was surprising because initial DFT calculations predicted values that were 30-40 cm-1 higher, consistent with intuition but not with the data. Modification of the basis sets and use of alternative functionals improved computational accuracy for the methoxide and acetate complexes, but calculated values for the hydroxide were greater than the measurement regardless of the computational method used. Attachment of a neutral donor ligand S to [UO2A]+ produced [UO2AS]+, which produced only very modest changes to the uranyl antisymmetric stretch frequency, and did not universally shift the frequency to lower values. DFT calculations for [UO2AS]+ were in accord with trends in the data, and showed that attachment of the solvent was accommodated by weakening of the U-anion bond as well as the uranyl. When uranyl frequencies were compared for [UO2AS]+ species having different solvent neutrals, values decreased with increasing neutral nucleophilicity

  12. Uranyl tris-beta-diketonate complexes

    International Nuclear Information System (INIS)

    Sidorenko, G.V.; Adamov, V.M.; Shcherbakova, L.L.; Suglubov, D.N.

    1986-01-01

    Uranyl tris-pivaloyltrifluoroacetonates (M/IOTA/UO 2 L 3 ; M/IOTA/ = Na, K, Cs, 1/2Ba, NR 4 ; R = C 8 H 17 ) and tris-dipivaloylmethanate (M/IOTA/UO 2 L/IOTA/ 3 , M/IOTA/ = K) have been synthesized for the first time. The compounds were characterized by chemical analysis and IR, NMR, and mass spectra. NaUO 2 L 3 , KUO 2 L 3 , CsUO 2 L 3 and Ba(UO 2 ) 2 L 6 sublime in high vacuum with partial decomposition. Specifically, decomposition gives UL 4 , identified by mass spectrometry. All the tris-complexes except those with outer-sphere NR 4 cation are characterized by an asymmetric structure of the uranyl group, recorded by IR spectroscopy using isotopic substitution of 18 O in uranyl. NMR spectra of the tris-complexes indicate the equivalence of all beta-diketonate groups, i.e., a coordination number of six for uranyl

  13. Sintering, microstructural and dilatometric studies of combustion synthesized Synroc phases

    International Nuclear Information System (INIS)

    Muthuraman, M.; Patil, K.C.; Senbagaraman, S.; Umarji, A.M.

    1996-01-01

    Sintering, microstructure, and linear thermal expansion properties of Synroc-B and constituent phases, viz. perovskite CaTiO 3 , zirconolite ZrTi 2 O 7 , hollandite (ideal formula BaAl2Ti 6 O 16 ) have been investigated. Synroc-B powder when pelletized and sintered at 1250 C for 2 h achieved >95% theoretical density. Sintered Synroc-B has a linear thermal expansion coefficient α of 8.72 x 10 -6 K -1 and Vicker's microhardness 9.88 GPa. The linear thermal expansion curves did not show any hysteresis indicating the absence of microcracking in the sintered bodies

  14. Influence of uranyl dibutylphosphate on the UV/VIS spectrophotometric online monitoring of uranium in tributylphosphate/hydrocarbon solvent

    International Nuclear Information System (INIS)

    Creech, E.T.; Rutenberg, A.C.; Smithwick, R.W.; Seals, R.D.

    1984-01-01

    In the uranium recovery process at the Y-12 Plant uranium is recovered from aqueous uranyl solutions by extraction into a solvent consisting of 30% tributylphosphate (TBP) and 70% hydrocarbon solvent. Within this process the uranium is continuously monitored by a UV/VIS absorbance measurement of the uranyl/tributylphosphate complex in the organic phase. The uranium is then further extracted from the organic phase to a final water phase. Dibutylphosphate (DBP), which is a decomposition product of TBP, builds up in the organic solvent. A very strong complex of uranyl/dibutylphosphate is formed which cannot be extracted into the aqueous phase. Prior to this work the uranyl/dibutylphosphate complex absorbance was assumed to be the same as the uranyl tributylphosphate complex. To determine the effect of the presence of uranyl/dibutylphosphate on the continuous UV/VIS monitor required (a) the purification of commercial dibutylphosphate, (b) the synthesis, and (c) the characterization of uranyl/dibutylphosphate

  15. Separation of uranyl ion using polyaniline

    International Nuclear Information System (INIS)

    Jayshree Ramkumar; Chandramouleeswaran, S.

    2013-01-01

    Polyaniline (Pani) was synthesized by the chemical oxidation of aniline. The use of persulphate instead of dichromate was desired in order to avoid the incorporation of chromium in the polymer matrix. The presence of chromium in the matrix, when dichromate was used as an oxidant, was confirmed by various techniques. The batch mode experiments showed that Pani could be used for separation of different metal ions. These ions were converted into their anionic complexes using suitable complexing agents. It was found that EDTA was used as a suitable reagent for the separation of Cu 2+ from Zn 2+ whereas the uranyl ion uptake could be increased to about 95 % when carbonate was used instead of EDTA as complexing agent. A possible application of the above exchange system to preconcentration of uranyl ion from seawater has also been examined. (author)

  16. On uranyl phosphites

    International Nuclear Information System (INIS)

    Avduevskaya, K.A.; Ragulina, N.B.; Rozanov, I.A.; Koval', E.M.

    1978-01-01

    The medium and single-substituted uranyl phosphites of the UO 2 HPO 3 x 3H 2 O and UO 2 (H 2 PO 3 ) 2 x3H 2 O composition were separated in crystal state for the first time. The medium phosphite is fully dehydrated above H 2 SO 4 , intermediate hydrates not being formed. Waterless phosphite decomposes at the temperature above 360 deg C into the mixture of uranium and uranyl phosphates, hydrogen being liberated. The thermal decomposition of single-substituted phosphite starts at the temperature above 150 deg C and is accompanied by the full reduction of uranium up to U(4). The product of calcination is identified as cubic UP 2 O 7

  17. Nanosize stabilization of cubic and tetragonal phases in reactive plasma synthesized zirconia powders

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, S., E-mail: sjayakumar.physics@gmail.com [Research and Development Centre, Bharathiar University, Coimbatore 641 014 (India); Department of Physics, Pollachi Institute of Engineering and Technology, Pollachi 642 205 (India); Ananthapadmanabhan, P.V.; Thiyagarajan, T.K. [Laser and Plasma Technology Division, BARC, Trombay, Mumbai 400 085 (India); Perumal, K. [Vision for Wisdom, Temple of Consciousness, Aliyar 642 101 (India); Mishra, S.C. [Department of Metallurgical and Materials Engg, National Institute of Technology, Rourkela 769 008 (India); Suresh, G. [Department of Physics, Park College of Engineering and Technology, Coimbatore 641 659 (India); Su, L.T.; Tok, A.I.Y. [School of Materials Science and Engg, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639 798 (Singapore)

    2013-06-15

    Pure zirconium oxide powders with particle size 2–33 nm are synthesized by reactive plasma processing. Transmission electron microscopy investigation of these particles revealed size dependent behavior for their phase stabilization. The monoclinic phase is found to be stable when particle size is ≥20 nm; Tetragonal is found to be stabilized in the range of 7–20 nm and as the particle size decreases to 6 nm and less, the cubic phase is stabilized. - Highlights: ► Direct conversion of micron-sized zirconium hydride powder to single crystal ZrO{sub 2} nanopowder. ► Size dependent stabilization of cubic, tetragonal and monoclinic phases in the reactive plasma synthesized ZrO{sub 2} nanopowder. ► Transmission electron microscopic investigation to identify particles of different sizes and their corresponding phase structure.

  18. Analysis Ratio of Uranyl/Urea and Uranyl/HMTA on the ComplexesUranyl-Urea and Uranyl-HMTA with Spectrophotometry Method

    International Nuclear Information System (INIS)

    Simbolon, Sahat

    2000-01-01

    Reaction between uranyl and urea and uranyl and HMTA was investigated atpH = 4 and room temperature. The result of the reaction was measured withspectrophotometer, each absorbance was pictured between mol fraction andabsorbance for uranyl - urea and uranyl - HMTA. The linear and horizontalcurve was found for reaction uranyl - urea, meanwhile S curve for thereaction uranyl and HMTA. It was found that reaction between uranyl and HMTAon mol fraction value less than 0.25 was complexes meanwhile on the range of0.25 and 0.5 the reaction between uranyl and HMTA was stoichiometries.(author)

  19. Volatile uranyl hexafluoroacetoacetonate complexes

    International Nuclear Information System (INIS)

    Dines, M.B.; Hall, R.B.; Kaldor, A.; Kramer, G.M.; Maas, E.T. Jr.

    1980-01-01

    A composition of matter is described, characterized by the formula UO 2 (CF 3 COCHCOCF 3 ).L where L is a ligand selected from isopropanol, ethanol, isobutanol, tert-butanol, methanol, tetrahydrofuran, acetone, dimethylformamide, n-propanol and ethyl acetate. A process for producing the complex comprises reacting uranyl chloride with a hexafluoroacetylacetonate dissolved in a ligand L: experimental details are given. (U.K.)

  20. The bare uranyl(2+) ion, UO22+

    International Nuclear Information System (INIS)

    Cornehl, H.H.; Heinemann, C.; Marcalo, J.; Pires de Matos, A.; Schwarz, H.

    1996-01-01

    Ion-molecule reactions between U 2+ and oxygen donors or charge-stripping collisions between singly charged UO 2 2 ions and O 2 collision partners generate uranyl(2+) ions in the gas phase. These do not readily dissociate into singly charged fragments. The standard enthalpy of formation for UO 2 2+ is estimated to be 371±60 kcal mol -1 , in accord with the results of ab initio calculations. (orig.)

  1. Spectroscopic characterization of alkaline earth uranyl carbonates

    International Nuclear Information System (INIS)

    Amayri, Samer; Reich, Tobias; Arnold, Thuro; Geipel, Gerhard; Bernhard, Gert

    2005-01-01

    A series of alkaline uranyl carbonates, M[UO 2 (CO 3 ) 3 ].nH 2 O (M=Mg 2 , Ca 2 , Sr 2 , Ba 2 , Na 2 Ca, and CaMg) was synthesized and characterized by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) after nitric acid digestion, X-ray powder diffraction (XRD), and thermal analysis (TGA/DTA). The molecular structure of these compounds was characterized by extended X-ray absorption fine-structure (EXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS). Crystalline Ba 2 [UO 2 (CO 3 ) 3 ].6H 2 O was obtained for the first time. The EXAFS analysis showed that this compound consists of (UO 2 )(CO 3 ) 3 clusters similar to the other alkaline earth uranyl carbonates. The average U-Ba distance is 3.90+/-0.02A.Fluorescence wavelengths and life times were measured using time-resolved laser-induced fluorescence spectroscopy (TRLFS). The U-O bond distances determined by EXAFS, TRLFS, XPS, and Raman spectroscopy agree within the experimental uncertainties. The spectroscopic signatures observed could be useful for identifying uranyl carbonate species adsorbed on mineral surfaces

  2. Training of secondary phases on UO{sub 2}. Uranyl phosphates and uranium peroxide; Formacion de fases secundarias sobre UO{sub 2}. Fosfatos de uranilo y peroxido de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez, J.; Rey, A.; Pablo, J. de; Casas, I.

    2008-07-01

    One of the main processes that can control radionuclides migration is mineral phase precipitation, known as secondary phases. The formation of one of these phases more stable than UO{sub 2} at repository conditions, could act as a barrier between nuclear waste and groundwater. This modifies the radiation that arrives to the dissolution, blocking dissolution of UO{sub 2} matrix and affecting to radionuclide release. So, is important to know the possible secondary phases to precipitate during SNF (spent nuclear fuel) alteration and its stability at repository conditions. Several experiments of SNF dissolution in groundwater have observed the formation of uranium secondary phases. Nevertheless, these experiments have been developed in specific conditions and they haven't arrived to study the effect of several parameters, such as complexions as phosphate. The rol of phosphate on to dissolution of UO{sub 2} and uranium-phosphate phase formation is necessary to know repository assessment. Uranyl peroxides have been found also in several studies about lixiviation in presence of hydrogen peroxide, which is the expected oxidant for med from the water radiolysis. In this work we performed a study about the stability of these phases. The phases obtained have been characterized with X ray diffraction (XRD). The particle size, shape and chemical composition have been studied by scanning electron microscopy (SEM). A topographic analysis of UO{sub 2} surface in contact with ground water and phosphate media have been performed by means of atomic force microscopy (AFM). The uranium concentration evolution in solution have been followed with ICP-MS. Stability in relation to radiation of uranyl peroxide have been developed with electron transmission microscopy (TEM), and thermal stability with a thermo gravimetry device (TG) and Differential scanning calorimetry (DSC). (Author)

  3. Benchmarking uranyl peroxide capsule chemistry in organic media

    Energy Technology Data Exchange (ETDEWEB)

    Neal, Harrison A.; Nyman, May [Department of Chemistry, Oregon State University, Corvallis, OR (United States); Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN (United States)

    2017-01-03

    Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Benchmarking uranyl peroxide capsule chemistry in organic media

    International Nuclear Information System (INIS)

    Neal, Harrison A.; Nyman, May; Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C.

    2017-01-01

    Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Uranyl Oxalate Solubility

    Energy Technology Data Exchange (ETDEWEB)

    Leturcq, G.; Costenoble, S.; Grandjean, S. [CEA Marcoule DEN/DRCP/SCPS/LCA - BP17171 - 30207 Bagnols sur Ceze cedex (France)

    2008-07-01

    The solubility of uranyl oxalate was determined at ambient temperature by precipitation in oxalic-nitric solutions, using an initial uranyl concentration of 0.1 mol/L. Oxalic concentration varied from 0.075 to 0.3 mol/L while nitric concentration ranged between 0.75 and 3 mol/L. Dissolution tests, using complementary oxalic-nitric media, were carried out for 550 hours in order to study the kinetic to reach thermodynamic equilibrium. Similar solubility values were reached by dissolution and precipitation. Using the results, it was possible to draw the solubility surface versus oxalic and nitric concentrations and to determine both the apparent solubility constant of UO{sub 2}C{sub 2}O{sub 4}, 3H{sub 2}O (Ks) and the apparent formation constant of the first uranyl-oxalate complex UO{sub 2}C{sub 2}O{sub 4} (log {beta}1), for ionic strengths varying between 1 and 3 mol/L. Ks and log {beta}1 values were found to vary from 1.9 10{sup -8} to 9.2 10{sup -9} and from 5.95 to 6.06, respectively, when ionic strength varied from 1 to 3 mol/L. A second model may fit our data obtained at an ionic strength of 3 mol/L suggesting as reported by Moskvin et al. (1959) that no complexes are formed for [H{sup +}] at 3 M. The Ks value would then be 1.3 10{sup -8}. (authors)

  6. Thermochemical investigations on uranyl phosphates and arsenates

    International Nuclear Information System (INIS)

    Barten, H.

    1986-01-01

    Results are described of a study of the thermochemical stability of anhydrous phosphates and arsenates. The results of phase studies deal with compound formation and characterization, coexisting phases and limiting physical or chemical properties. The uranyl phosphates evolve oxygen at higher temperatures and the arsenates lose arsenic oxide vapour. These phenomena give the possibility to describe their thermodynamic stabilities. Thus oxygen pressures of uranyl phosphates have been measured using a static, non-isothermal method. Having made available the pure anhydrous compounds in the course of this investigation, molar thermodynamic quantities have been measured as well. These include standard enthalpies of formation from solution calorimetry and high-temperature heat-capacity functions derived from enthalpy increments measured. Some attention is given to compounds with uranium in valencies lower than six which have been met during the investigation. An evaluation is made of the thermodynamics of the compounds studied, to result in tabulized high-temperature thermodynamic functions. Relative stabilities within the systems are discussed and comparisons of the uranyl phosphates and the arsenates are made. (Auth.)

  7. Preparation of working calibration and test materials: uranyl nitrate solution

    International Nuclear Information System (INIS)

    Yamamura, S.S.; Spraktes, F.W.; Baldwin, J.M.; Hand, R.L.; Lash, R.P.

    1977-05-01

    Reliable working calibration and test materials (WCTMs) are essential to a meaningful analytical measurements quality assurance program. This report describes recommended methods for the preparation of uranyl nitrate solution WCTMs for testing analytical methods, for calibrating methods, and for testing personnel. Uranyl nitrate solution WCTMs can be synthesized from characterized starting materials or prepared from typical plant materials by thorough characterization with reference to primary or secondary reference calibration and test materials (PRCTMs or SRCTMs). Recommended starting materials are described along with detailed procedures for (a) preparing several widely-used types of uranyl nitrate solution WCTMs, (b) packaging the WCTMs, (c) analyzing the WCTMs to establish the reference values or to confirm the synthesis, and (d) statistically evaluating the analytical data to assign reference values and to assess the accuracy of the WCTMs

  8. Crystal chemistry of uranyl carboxylate coordination networks obtained in the presence of organic amine molecules

    Energy Technology Data Exchange (ETDEWEB)

    Mihalcea, Ionut; Henry, Natacha; Loiseau, Thierry [Unite de Catalyse et Chimie du Solide (UCCS) - UMR CNRS 8181, Universite de Lille Nord de France, USTL-ENSCL, Villeneuve d' Ascq (France)

    2014-03-15

    Three uranyl isophthalates (1,3-bdc) and two uranyl pyromellitates (btec) of coordination-polymer type were hydrothermally synthesized (200 C for 24 h) in the presence of different amine-based molecules [1,3-diaminopropane (dap) or dimethylamine (dma) originating from the in situ decomposition of N,N-dimethylformamide]. (UO{sub 2}){sub 2}(OH){sub 2}(H{sub 2}O)(1,3-bdc).H{sub 2}O (1) is composed of inorganic tetranuclear cores, which are linked to each other through the isophthalato ligand to generate infinite neutral ribbons, which are intercalated by free H{sub 2}O molecules. The compounds (UO{sub 2}){sub 1.5}(H{sub 2}O)(1,3-bdc){sub 2}.0.5H{sub 2}dap.1.5H{sub 2}O (2) and UO{sub 2}(1,3-bdc){sub 1.5}.0.5H{sub 2}dap.2H{sub 2}O (3) consist of discrete uranyl-centered hexagonal bipyramids connected to each other by a ditopic linker to form a single-layer network for 2 or a double-layer network for 3. The protonated diamine molecules are located between the uranyl-organic sheets and balance the negative charge of the layered sub-networks. The phase (UO{sub 2}){sub 2}O(btec).2Hdma.H{sub 2}O (4) presents a 2D structure built up from tetranuclear units, which consist of two central sevenfold coordinated uranium centers and two peripheral eightfold coordinated uranium centers. The connection of the resulting tetramers through the pyromellitate molecules generates an anionic layerlike structure, in which the protonated dimethylammonium species are inserted. The compound UO{sub 2}(btec).2Hdma (5) is also a lamellar coordination polymer, which contains isolated eightfold coordinated uranium cations linked through pyromellitate molecules and intercalated by protonated dimethylammonium species. In both phases 4 and 5, the btec linker has non-bonded carboxyl oxygen atoms, which preferentially interact with the protonated amine molecules through a hydrogen-bond network. The different illustrations show the structural diversity of uranyl-organic coordination polymers with organic

  9. A fully-differential phase-locked loop frequency synthesizer for 60-GHz wireless communication

    International Nuclear Information System (INIS)

    Kuang Lixue; Chi Baoyong; Chen Lei; Wang Zhihua; Jia Wen

    2014-01-01

    A 40-GHz phase-locked loop (PLL) frequency synthesizer for 60-GHz wireless communication applications is presented. The electrical characteristics of the passive components in the VCO and LO buffers are accurately extracted with an electromagnetic simulator HFSS. A differential tuning technique is utilized in the voltage controlled oscillator (VCO) to achieve higher common-mode noise rejection and better phase noise performance. The VCO and the divider chain are powered by a 1.0 V supply while the phase-frequency detector (PFD) and the charge pump (CP) are powered by a 2.5 V supply to improve the linearity. The measurement results show that the total frequency locking range of the frequency synthesizer is from 37 to 41 GHz, and the phase noise from a 40 GHz carrier is −97.2 dBc/Hz at 1 MHz offset. Implemented in 65 nm CMOS, the synthesizer consumes a DC power of 62 mW, including all the buffers. (semiconductor integrated circuits)

  10. A fully-differential phase-locked loop frequency synthesizer for 60-GHz wireless communication

    Science.gov (United States)

    Lixue, Kuang; Baoyong, Chi; Lei, Chen; Wen, Jia; Zhihua, Wang

    2014-12-01

    A 40-GHz phase-locked loop (PLL) frequency synthesizer for 60-GHz wireless communication applications is presented. The electrical characteristics of the passive components in the VCO and LO buffers are accurately extracted with an electromagnetic simulator HFSS. A differential tuning technique is utilized in the voltage controlled oscillator (VCO) to achieve higher common-mode noise rejection and better phase noise performance. The VCO and the divider chain are powered by a 1.0 V supply while the phase-frequency detector (PFD) and the charge pump (CP) are powered by a 2.5 V supply to improve the linearity. The measurement results show that the total frequency locking range of the frequency synthesizer is from 37 to 41 GHz, and the phase noise from a 40 GHz carrier is -97.2 dBc/Hz at 1 MHz offset. Implemented in 65 nm CMOS, the synthesizer consumes a DC power of 62 mW, including all the buffers.

  11. Probing uranyl(VI) speciation in the presence of amidoxime ligands using electrospray ionization mass spectrometry.

    Science.gov (United States)

    Mustapha, Adetayo M; Pasilis, Sofie P

    2013-10-15

    Extraction processes using poly(acrylamidoxime) resins are being developed to extract uranium from seawater. The main complexing agents in these resins are thought to be 2,6-dihydroxyiminopiperidine (DHIP) and N(1),N(5)-dihydroxypentanediimidamide (DHPD), which form strong complexes with uranyl(VI) at the pH of seawater. It is important to understand uranyl(VI) speciation in the presence of these and similar amidoxime ligands to understand factors affecting uranyl(VI) adsorption to the poly(acrylamidoxime) resins. Experiments were carried out in positive ion mode on a quadrupole ion trap mass spectrometer equipped with an electrospray ionization source. The ligands investigated were DHIP, DHPD, and N(1),N(2)-dihydroxyethanediimidamide (DHED). DHED and DHPD differ only in the number of carbons separating the oxime groups. The effects on the mass spectra of changes in uranyl(VI):ligand ratio, pH, and ligand type were examined. DHIP binds uranyl(VI) more effectively than DHPD or DHED in the pH range investigated, forming ions derived from solution-phase species with uranyl(VI):DHIP stoichiometries of 1:1, 1:2, and 2:3. The 2:3 uranyl(VI):DHIP complex appears to be a previously undescribed solution species. Ions related to uranyl(VI):DHPD complexes were detected in very low abundance. DHED is a more effective complexing agent for uranyl(VI) than DHPD, forming ions having uranyl(VI):DHED stoichiometries of 1:1, 1:2, 1:3, and 2:3. This study presents a first look at the solution chemistry of uranyl(VI)-amidoxime complexes using electrospray ionization mass spectrometry. The appearance of previously undescribed solution species suggests that the uranyl-amidoxime system is a rich and relatively complex one, requiring a more in-depth investigation. Copyright © 2013 John Wiley & Sons, Ltd.

  12. Uranyl sorption onto alumina

    International Nuclear Information System (INIS)

    Jacobsson, A.M.M.

    1997-01-01

    The mechanism for the adsorption of uranyl onto alumina from aqueous solution was studied experimentally and the data were modeled using a triple layer surface complexation model. The experiments were carried out at low uranium concentrations (9 x 10 -11 --5 x 10 -8 M) in a CO 2 free environment at varying electrolyte concentrations (0.01--1 M) and pH (4.5--12). The first and second acid dissociation constants, pK a1 and pK a2 , of the alumina surface were determined from potentiometric titrations to be 7.2 ± 0.6 and 11.2 ± 0.4, respectively. The adsorption of uranium was found to be independent of the electrolyte concentration. The authors therefore conclude that the uranium binds as an inner sphere complex. The results were modeled using the code FITEQL. Two reactions of uranium with the surface were needed to fit the data, one forming a uranyl complex with a single surface hydroxyl and the other forming a bridged or bidentate complex reacting with two surface hydroxyls of the alumina. There was no evidence from these experiments of site heterogeneity. The constants used for the reactions were based in part on predictions made utilizing the Hard Soft Acid Base, HSAB, theory, relating the surface complexation constants to the hydrolysis of the sorbing metal ion and the acid dissociation constants of the mineral oxide surface

  13. In vitro toxicity test of nano-sized magnesium oxide synthesized via solid-phase transformation

    Science.gov (United States)

    Zheng, Jun; Zhou, Wei

    2018-04-01

    Nano-sized magnesium oxide (MgO) has been a promising potential material for biomedical pharmaceuticals. In the present investigation, MgO nanoparticles synthesized through in-situ solid-phase transformation based on the previous work (nano-Mg(OH)2 prepared by precipitation technique) using magnesium nitrate and sodium hydroxide. The phase structure and morphology of the MgO nanoparticles are characterized by X-ray powder diffraction (XRD), selected area electronic diffraction (SAED) and transmission electron microscopy (TEM) respectively. In vitro hemolysis tests are adopted to evaluate the toxicity of the synthesized nano-MgO. The results evident that nano-MgO with lower concentration is slightly hemolytic, and with concentration increasing nano-MgO exhibit dose-responsive hemolysis.

  14. Synthesis and physicochemical properties of uranyl molybdate complexes of ammonium, potassium, rubidium, and cesium ions

    International Nuclear Information System (INIS)

    Fedoseev, A.M.; Budantseva, N.A.; Shirokova, I.B.; Yurik, T.K.; Andreev, G.B.; Krupa, Zh-K.

    2001-01-01

    Effect of experimental conditions on composition and intimacy of yield of crystal phases in the UO 2 MoO 4 -M 2 MoO 4 -H 2 O system, where M is cation of alkali metal or ammonium, is studied. The compounds of morphotropic raw with overall formula M 2 UO 2 (MoO 4 ) 2 ·H 2 O, where M=K, Ru, Cs, NH 4 , are synthesized by hydrothermal method from aqueous solutions at 160-180 Deg C. The dependence of composition and certain physico-chemical properties of the binary uranyl molybdates is investigated from the nature of out-spherical cation as well as IR-spectra and thermal behavior of synthesized compounds are inspected [ru

  15. A non-binary direct digital synthesizer with an extended phase accumulator.

    Science.gov (United States)

    Nosaka, H; Yamaguchi, Y; Muraguchi, M

    2001-01-01

    We describe a new direct digital synthesizer (DDS) in which output tuning resolution is flexibly controlled. The new DDS has an extended phase accumulator (EPA) controlled by two frequency control words; one determines the wave number within a single EPA operation cycle, and the other determines the length of the cycle. The EPA allows the DDS to provide jitter-free signals, the frequencies of which are given by arbitrary fractional expressions. (The denominator is fixed in conventional DDS that use normal phase accumulators.) Experimental results showed that the EPA worked well, allowing flexible output tuning resolution.

  16. Amorphous phase formation in intermetallic Mg2Ni alloy synthesized by ethanol wet milling

    International Nuclear Information System (INIS)

    Wang, H.-W.; Chyou, S.-D.; Wang, S.-H.; Yang, M.-W.; Hsu, C.-Y.; Tien, H.-C.; Huang, N.-N.

    2009-01-01

    The hydriding/dehydriding properties of an intermetallic Mg 2 Ni alloy synthesized by wet ball milling in ethanol have been investigated. The appearance of the particle surface after different milling methods is one obvious difference. The alloyed powders prepared by either dry milling or wet milling under ethanol were characterized for phase content by X-ray diffractometer (XRD). The results show that two broad diffuse peaks, which are an ionic-organic-Mg amorphous material, appear in addition to the nickel element peaks. This unexpected amorphous phase has the special hydrogen absorbing/desorbing features.

  17. Barium uranyl diphosphonates

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Anna-Gay D., E-mail: nelsoa@umich.edu [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Alekseev, Evgeny V. [Institute of Energy and Climate Research (IEK-6), Forschungszentrum Juelich Wilhelm-Johnen-Strasse, Juelich 52428 (Germany); Ewing, Rodney C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Albrecht-Schmitt, Thomas E. [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2012-08-15

    Three Ba{sup 2+}/UO{sub 2}{sup 2+} methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200 Degree-Sign C. These compounds, Ba[UO{sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{center_dot}1.4H{sub 2}O (Ba-1), Ba{sub 3}[(UO{sub 2}){sub 4}(CH{sub 2}(PO{sub 3}){sub 2}){sub 2}F{sub 6}]{center_dot}6H{sub 2}O (Ba-2), and Ba{sub 2}[(UO{sub 2}){sub 2}(CH{sub 2}(PO{sub 3}){sub 2})F{sub 4}]{center_dot}5.75H{sub 2}O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO{sub 5}F{sub 2} pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO{sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{sup 2-} sheets. The interlayer space of the structures is occupied by Ba{sup 2+}, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance. - Graphical abstract: Illustration of the stacking of the layers in Ba{sub 3}[(UO{sub 2}){sub 4}(CH{sub 2}(PO{sub 3}){sub 2}){sub 2})F{sub 6}]{center_dot}6H{sub 2}O viewed along the c-axis. The structure is constructed from UO{sub 7} pentagonal bipyramidal units, U(1)O{sub 7}=gray, U(2)O{sub 7}=yellow, barium=blue, phosphorus=magenta, fluorine=green, oxygen=red, carbon=black, and hydrogen=light peach. Highlights: Black-Right-Pointing-Pointer The polymerization of the UO{sub 2}{sup 2+} sites to form uranyl dimers leads to structural variations in compounds. Black-Right-Pointing-Pointer Barium cations stitch uranyl diphosphonate anionic layers together, and help mediate structure formation. Black-Right-Pointing-Pointer HF acts as both a

  18. Phase controlled synthesis and cathodoluminescence properties of ZnS nanobelts synthesized by PVD

    Science.gov (United States)

    Jin, Changqing; Zhu, Kexin; Peterson, George; Zhang, Zhihong; Jian, Zengyun; Wei, Yongxing; Zheng, Deshan

    2018-01-01

    Zinc sulfide (ZnS) nanobelts were synthesized via physical vapor deposition to explore the electronic properties of optoelectronic nano-devices. It was determined that the mass ratio of wurtzite (WZ) phase to zincblende (ZB) phase and the preferential orientation (100) are related to the carrier-gas flow rate. The high concentration of planar defects within the phase boundary enhances phase transition. Cathodoluminescence measurements show a red shift of the 337 nm band-gap emission due to stacking and twin faults. We find a direct correlation between the magnitude of the red shift and the mass ratio of ZB phase. With an increase in the ZB phase, there is an increase in the concentration of stacking and twin faults introduced by the phase transformation, as indicated by an increasing red shift in the data. The absorption peaks at 666 and 719 nm were found by UV-vis absorption spectrum, which is attributed to surface defects. This work would help to better understand the important roles of planar defects in the phase transition and also provide us with a feasible route to control phase ratio and cathodoluminescence properties of ZnS nanobelts and other II-VI semiconductor nanostructures.

  19. Infrared studies on complexes between octaethyltetraamidepyrophosphate (OETAPP) and uranyl salts

    International Nuclear Information System (INIS)

    Grychowski, P.; Mikulski, J.; Moravets, Ya.; Shara, V.; Shourkova, L.

    1981-01-01

    Uranyl nitrate and uranyl chloride were extracted from the water phase with CHCl 3 solution of octaethyltetraamidepyrophosphate (OETAPP). Infrared spectra of the organic phases were recorded before and after the extraction. For both systems, the frequency of the P=O stretching mode of OETAPP after the extraction was lowered, which indicates for the formation of OETAPP UO 2 (NO 3 ) 2 and OETAPP UO 2 Cl 2 complexes. If uranyl nitrate was extracted with OETAPP in CCl 4 a precipitate was formed in the solution. From the analysis of the IR spectrum of the precipitate it was concluded that the complex OETAPP UO 2 (NO 3 ) 2 was formed also in this case, however, the complex was insoluble in CCl 4 . (author)

  20. Series of mixed uranyl-lanthanide (Ce, Nd) organic coordination polymers with aromatic polycarboxylates linkers.

    Science.gov (United States)

    Mihalcea, Ionut; Volkringer, Christophe; Henry, Natacha; Loiseau, Thierry

    2012-09-17

    Three series of mixed uranyl-lanthanide (Ce or Nd) carboxylate coordination polymers have been successfully synthesized by means of a hydrothermal route using either conventional or microwave heating methods. These compounds have been prepared from mixtures of uranyl nitrate, lanthanide nitrate together with phthalic acid (1,2), pyromellitic acid (3,4), or mellitic acid (5,6) in aqueous solution. The X-ray diffraction (XRD) single-crystal revealed that the phthalate complex (UO(2))(4)O(2)Ln(H(2)O)(7)(1,2-bdc)(4)·NH(4)·xH(2)O (Ln = Ce(1), Nd(2); x = 1 for 1, x = 0 for 2), is based on the connection of tetranuclear uranyl-centered building blocks linked to discrete monomeric units LnO(2)(H(2)O)(7) via the organic species to generate infinite chains, intercalated by free ammonium cations. The pyromellitate phase (UO(2))(3)Ln(2)(H(2)O)(12)(btec)(3)·5H(2)O (Ce(3), Nd(4)) contains layers of monomeric uranyl-centered hexagonal and pentagonal bipyramids linked via the carboxylate arms of the organic molecules. The three-dimensionality of the structure is ensured by the connection of remaining free carboxylate groups with isolated monomeric units LnO(2)(H(2)O)(7). The network of the third series (UO(2))(2)(OH)Ln(H(2)O)(7)(mel)·5H(2)O (Ce(5), Nd(6)) is built up from dinuclear uranyl units forming layers through connection with the mellitate ligands, which are further linked to each other through discrete monomers LnO(3)(H(2)O)(6). The thermal decomposition of the various coordination complexes led to the formation of mixed uranium-lanthanide oxide, with the fluorite-type structure at 1500 °C (for 1, 2) or 1400 °C for 3-6. Expected U/Ln ratio from the crystal structures were observed for compounds 1-6.

  1. Spectroscopic studies of 2-thenoyltrifluoro acetonate of uranyl salts doped with europium

    International Nuclear Information System (INIS)

    Nakagawa, F.T.; Luiz, J.E.M. de Sa; Felinto, M.C.F.C.; Brito, H.F.; Teotonio, E.E.S.

    2006-01-01

    Uranyl compounds present a great potential as luminescence materials. Some examples of applications are: in laser technology, cathode ray tube, X-rays diagnostic. In this work it was studied the synthesis, characterization and spectroscopic properties study of uranyl 2-thenoyl trifluoroacetonate and uranyl 2- thenoyl trifluoroacetonate doped with europium. The compounds were synthesized and characterized by infrared absorption spectroscopy, thermal analysis, scanning electronic microscopy, and electronic spectroscopy of emission and excitation. The Eu 3+ ion acted as an effective luminescent probe, however the process of energy transfer from UO 2 2+ to Eu 3+ ion has not been efficient. (author)

  2. Solid solutions of hydrogen uranyl phosphate and hydrogen uranyl arsenate. A family of luminescent, lamellar hosts

    International Nuclear Information System (INIS)

    Dorhout, P.K.; Rosenthal, G.L.; Ellis, A.B.

    1988-01-01

    Hydrogen uranyl phosphate, HUO 2 PO 4 x 4H 2 O (HUP), and hydrogen uranyl arsenate, HUO 2 AsO 4 x 4H 2 O (HUAs), form solid solutions of composition HUO 2 (PO 4 ) 1-x (AsO 4 )x (HUPAs), representing a family of lamellar, luminescent solids that can serve as hosts for intercalation chemistry. The solids are prepared by aqueous precipitation reactions from uranyl nitrate and mixtures of phosphoric and arsenic acids; thermogravimetric analysis indicates that the phases are tetrahydrates, like HUP and HUAs. Powder x-ray diffraction data reveal the HUPAs solids to be single phases whose lattice constants increase with X, in rough accord with Vegard's law Spectral shifts observed for the HUPAs samples. Emission from the solids is efficient (quantum yields of ∼ 0.2) and long-lived (lifetimes of ∼ 150 μs), although the measured values are uniformly smaller than those of HUP and HUAs; unimolecular radiative and nonradiative rate constants for excited-state decay of ∼ 1500 and 5000 s -1 , respectively, have been calculated for the compounds. 18 refs., 5 figs., 2 tabs

  3. Growth of uranyl hydroxide nanowires and nanotubes with electrodeposition method

    International Nuclear Information System (INIS)

    Wang Lin; Yuan Liyong; Chai Zhifang; Shi Weiqun

    2013-01-01

    Actinides nanomaterials have great potential applications in fabrication of novel nuclear fuel and spent fuel reprocessing in advanced nuclear energy system. However, the relative research so far still lacks systematic investigation on the synthetic methods for actinides nanomaterials. In this work, we use track-etched membranes as hard templates to synthesize uranium based nanomaterials with novel structures by electrodeposition method. Through electrochemical behavior investigations and subsequent product characterizations such as energy dispersive spectrometer (EDS), fourier transform infrared spectroscopy (FTIR), the chemical composition of deposition products have been confirmed as the uranyl hydroxide. More importantly, accurate control of morphology and structures (nanowires and nanotubes) could be achieved by carefully adjusting the growth parameters such as deposition time and deposition current density. It was found that the preferred morphology of electrodeposition products is nanowire when a low current density was applied, whereas nanotubes could be formed only under conditions of high current density and the short deposition time. The mechanism for the formation of nanowires in track-etched membranes is based on the precipitation of uranyl hydroxide from uranyl nitrate solution, according to the previous researches about obtaining nanostructures of hydroxides from nitrate salt solutions. And we have concluded that the formation of nanotubes is attributed to the hydrogen bubbles generated by water electrolysis under the condition of over-potential electro-reduction. The conveying of hydrogen bubbles plays the role of dynamic template which can prevent the complete filling of uranyl hydroxide in the channels. Additionally, we transform the chemical composition of deposition products from uranyl hydroxide to triuranium octoxide by calcining them at 500 and 800 degree centigrade, respectively, and SEM results show the morphologies of nanowires and

  4. Uranyl oxalate hydrates: structures and IR spectra

    International Nuclear Information System (INIS)

    Giesting, P.A.; Porter, N.J.; Burns, P.C.

    2006-01-01

    The novel compound (UO 2 ) 2 C 2 O 4 (OH) 2 (H 2 O) 2 (UrOx2A) and the previously studied compound UO 2 C 2 O 4 (H 2 O) 3 (UrOx3) have been synthesized by mild hydrothermal methods. Single crystal diffraction data collected at 125 K using MoK α radiation and a CCD-based area detector were used to solve and refine the crystal structures by full-matrix least-squares techniques to agreement indices (UrOx2A, UrOx3) wR 2 = 0.037, 0.049 for all data, and R1 0.015, 0.024 calculated for 1285, 2194 unique reflections respectively. The compound UrOx2A is triclinic, space group P1, Z = 1, a = 5.5353(4), b 6.0866(4), c = 7.7686(6) Aa, α = 85.6410(10) , β = 89.7740(10) , γ = 82.5090(10) , V = 258.74(3) Aa 3 . The compound UrOx3 is monoclinic, space group P2 1 /c, Z = 4, a = 5.5921(4), b = 16.9931(13), c = 9.3594(7) Aa, β = 99.5330(10) , V = 877.11(11) Aa 3 . The structures consist of chains of uranyl pentagonal bipyramids connected by oxalate groups and, in UrOx2A, hydroxyl groups; UrOx2A is also notable for its high (2:1) ratio of uranyl to oxalate groups, higher than any observed in other published structures of uranyl oxalates. The structure determined for UrOx3, previously studied by Jayadevan and Chackraburtty (1972); Mikhailov et al. (1999) is in agreement with the previous results; however, the increased precision of the present low-temperature structure refinement allows for the assignment of H atom positions based on the difference Fourier map of electron density. The infrared spectra of these two materials collected at room temperature are also presented and compared with previous work on uranyl oxalate systems. (orig.)

  5. Synthesis and characterization of heterometallic uranyl pyridinedicarboxylate compounds

    Science.gov (United States)

    Jayasinghe, Ashini S.; Payne, Maurice K.; Forbes, Tori Z.

    2017-10-01

    The incorporation of transition metals into hybrid uranyl materials can result in more diverse structural topologies and variations in physical and chemical properties. To explore the impact of transition metals on the uranyl cation, five uranium containing bimetallic chain compounds, [(UO2)M(PDC)2(H2O)4]·4(H2O) (PDC = 2,6 pyridinedicarboxylate; M = Ni2+, Co2+, Fe2+, Zn2+, and Cu2+) were synthesized by evaporation of aqueous solutions at room temperature. The uranyl cation is complex by two PDC ligands and the transition metal cations bond to the complex to form a one-dimensional chain topology. The presence of the transition metal leads to the presence of a stronger uranyl oxo bonds as shown by the single-crystal X-ray diffraction data and the Raman spectra. Solid state diffuse reflectance UV/Visible spectra confirmed the presence of the transition metals in the structure by the broad bands that appeared at relevant wavelengths.

  6. Influence of pH during modified sol-gel process to synthesized pure phased YBCO

    International Nuclear Information System (INIS)

    Barekat Rezaee, S.; Daadmehr, V.; Saeb, F.; Falahati, S.

    2007-01-01

    Full text: Among numerous studies of high-Tc superconductor compound, the YBCO system is the most studied system. During 3 last decades synthesized of high quality pure homogeneous powder were done. One of these methods was modified citrate gel that was widely used to obtain nanosized single phase YBCO. One of the most important factors to yield pure product is adjustment of the pH during the gelation. Then in this work, we adjusted different pH for gelatin and compare phase purity and elemental composition by using XRD and EDS. To synthesize the YBCO, we used Nitrate of metal (Y, Ba, Cu) as precursor. stoichiometric (1:2:3) amount of metal nitrate were solved in distilled water and mixed with constant stirring, (for each equivalent gram of metal nitrate add one equivalent gram of citric acid) and stirred up to have unclear light blue solution and the ethylendiamine was added drop wise to adjust pH from 4.56 to 7.45. Then the solution was heated up 80 C to achieve viscous gel. The color changed from dark blue to purple according to pH. The gel was heated on furnace up to 520 C and kept for 2 hours. During heating the gel swell and filled the baker then special attention is needed to use over sized baker. Obtained powder was calcined for 22h at 900 C to yield homogeneous pure phase and then pellets with 1 sm diameter in 10 ton pressure were produced and sintered for 19 h at 930 C and annealed to room temperature in oxygen. Resistivity measurement using standard four probe technique exhibit Tc (zero) from 90 K to 94 K. The samples were discussed by XRD, SEM and EDS. (authors)

  7. Magnetic properties and phase transformations of iron sulfides synthesized under the hydrothermal method

    Science.gov (United States)

    Li, S. H.; Chen, Y. H.

    2016-12-01

    The iron sulfide nano-minerals possess advantages of high abundance, low cost, and low toxicity. These advantages make them be competitive in the magnetic, electronic, and photoelectric applications. Mackinawite can be used in soil or water remediations. Greigite is very important for paleomagnetic and geochemical environment studies and the anode materials for lithium ion batteries. Besides, greigite is also utilized for hyperthermia and biomedicine. Pyrrhotite can be applied as geothermometry. Due to the above-mentioned reasons, iron sulfide minerals have specific significances and they must be further investigated, like their phase transformations, magnetic properties, and etc. In this study, the iron sulfide minerals were synthesized by using a hydrothermal method. The ex-situ and in-situ X-ray diffraction (XRD) was used to examine the crystal structure and phase transformation of iron sulfide minerals. The Transmission electron microscopy (TEM) and superconducting quantum interference device (SQUID) were carried out to investigate their morphology and magnetic properties, respectively. The results suggested that the phase transformation sequence was followed the order: mackinawite → greigite → (smythite) → pyrrhotite. Two pure mineral phases of greigite and pyrrhotite were obtained under the hydrothermal conditions. The morphology of the pure greigite is granular aggregates with a particle size of approximately 30 nm and pyrrhotite presented a hexagonal sheet stacking with a particle size of thousands nanometers. The greigite had a ferri-magnetic behavior and pyrrhotite was weak ferro-magnetic. Both of them had a pseudo-single magnetic domain (PSD) based on the Day's plot from SQUID data. The complete phase-transformation pathways and high magnetization of iron sulfide minerals are observed in this study and these kind of iron sulfide minerals are worthy to further study.

  8. A Phase-Separation Route to Synthesize Porous CNTs with Excellent Stability for Na+ Storage.

    Science.gov (United States)

    Chen, Zhi; Wang, Taihong; Zhang, Ming; Cao, Guozhong

    2017-06-01

    Porous carbon nanotubes (CNTs) are obtained by removing MoO 2 nanoparticles from MoO 2 @C core@shell nanofibers which are synthesized by phase-segregation via a single-needle electrospinning method. The specific surface area of porous CNTs is 502.9 m 2 g -1 , and many oxygen-containing functional groups (COH, CO) are present. As anodes for sodium-ion batteries, the porous CNT electrode displays excellent rate performance and cycling stability (110 mA h g -1 after 1200 cycles at 5 A g -1 ). Those high properties can be attributed to the porous structure and surface modification to steadily store Na + with high capacity. The work provides a facile and broadly applicable way to fabricate the porous CNTs and their composites for batteries, catalysts, and fuel cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. EXAFS Phase Retrieval Solution Tracking for Complex Multi-Component System: Synthesized Topological Inverse Computation

    International Nuclear Information System (INIS)

    Lee, Jay Min; Yang, Dong-Seok; Bunker, Grant B

    2013-01-01

    Using the FEFF kernel A(k,r), we describe the inverse computation from χ(k)-data to g(r)-solution in terms of a singularity regularization method based on complete Bayesian statistics process. In this work, we topologically decompose the system-matched invariant projection operators into two distinct types, (A + AA + A) and (AA + AA + ), and achieved Synthesized Topological Inversion Computation (STIC), by employing a 12-operator-closed-loop emulator of the symplectic transformation. This leads to a numerically self-consistent solution as the optimal near-singular regularization parameters are sought, dramatically suppressing instability problems connected with finite precision arithmetic in ill-posed systems. By statistically correlating a pair of measured data, it was feasible to compute an optimal EXAFS phase retrieval solution expressed in terms of the complex-valued χ(k), and this approach was successfully used to determine the optimal g(r) for a complex multi-component system.

  10. Detailed investigation of proposed gas-phase syntheses of ammonia in dense interstellar clouds

    International Nuclear Information System (INIS)

    Herbst, E.; Defrees, D.J.; Mclean, A.D.; Molecular Research Institute, Palo Alto, CA; IBM Almaden Research Center, San Jose, CA)

    1987-01-01

    The initial reactions of the Herbst and Klemperer (1973) and the Dalgarno (1974) schemes (I and II, respectively) for the gas-phase synthesis of ammonia in dense interstellar clouds were investigated. The rate of the slightly endothermic reaction between N(+) and H2 to yield NH(+) and H (scheme I) under interstellar conditions was reinvestigated under thermal and nonthermal conditions based on laboratory data. It was found that the relative importance of this reaction in synthesizing ammonia is determined by how the laboratory data at low temperature are interpreted. On the other hand, the exothermic reaction between N and H3(+) to form NH2(+) + H (scheme II) was calculated to possess significant activation energy and, therefore, to have a negligible rate coefficient under interstellar conditions. Consequently, this reaction cannot take place appreciably in interstellar clouds. 41 references

  11. Study On Precipitation Of UO2 Ex-AUC Powder. Part I: Precipitation Of AUC By (NH4)2CO3 From Uranyl Fluoride Solution

    International Nuclear Information System (INIS)

    Nguyen Trong Hung; Le Ba Thuan; Do Van Khoai; Nguyen Thanh Thuy; Nguyen Van Tung

    2011-01-01

    In this paper, Ammonium Uranyl Carbonate (AUC) powders were prepared by precipitation method in solution. UO 2 F 2 /HF, ammonium carbonate (AC), and ammonium hydroxide solution were used as precursors for precipitation. The influence of C/U ratio (mol/mol), AC concentration (g/L), reaction temperature ( o C), on characteristics of AUC powders was also investigated. Then, the synthesized AUC powders were analyzed (to define) phase composition (X-ray), fluorine content, morphology (by SEM), and specific surface area (BET). (author)

  12. Direct investigations of the immobilization of radionuclides in the alteration phases of spent nuclear fuel. 1998 annual progress report

    International Nuclear Information System (INIS)

    Burns, P.C.; Finch, R.J.

    1998-01-01

    'In an oxidizing environment, such as in the proposed repository at Yucca Mountain, rapid alteration rates are expected for spent nuclear fuel. Lab.-scale simulations have repeatedly shown that the dominant alteration products under repository conditions will be uranyl phases. There is an inadequate database that relates to the effects of the alteration products on the release of radionuclides, but this information is essential to provide a radionuclide release estimate. It is likely that many of the radionuclides contained in the fuel will be incorporated into the alteration products that form, potentially with a profound impact on the future mobility of radionuclides in the repository. The authors objective is to characterize the incorporation of radionuclides into alteration products by synthesis of uranyl phases doped with radionuclides, appropriate surrogate elements, or non-radioactive isotopes, followed by detailed phase characterization by diffraction and spectroscopic techniques. The research will permit a more realistic estimate of the release rates of the radionuclides from the near-field environment. This report summarizes work after 8 months of a 3-year project. The objective of investigating radionuclide incorporation in uranyl phases has required the development of synthesis techniques for various uranyl phases that are expected to form under repository conditions. The authors have synthesized and determined the structures of several uranyl phases that are new to science and that may be important alteration products under repository conditions. They have also undertaken the determination and refinement of the crystal structures of various uranyl phases that are likely to form under repository conditions. Other experiments include the investigation of the ion-exchange properties of uranyl phases under repository conditions.'

  13. Nanographene synthesized in triple-phase plasmas as a highly durable support of catalysts for polymer electrolyte fuel cells

    Science.gov (United States)

    Amano, Tomoki; Kondo, Hiroki; Takeda, Keigo; Ishikawa, Kenji; Hiramatsu, Mineo; Sekine, Makoto; Hori, Masaru

    2018-04-01

    Nanographene was synthesized in triple-phase plasmas comprising a gaseous phase, a gas-liquid boundary layer, and an in-liquid phase using a setup in which one electrode was placed in the gaseous phase while the other was immersed in the liquid phase. The triple-phase plasmas were generated using a pure alcohol, such as ethanol, 1-propanol, or 1-butanol, by applying a high voltage to a pair of electrodes made of copper or graphite. The nanographene synthesized using ethanol had high durability and thus could serve as a catalyst support in polymer electrolyte fuel cells (PEFCs). The PEFCs exhibited low degradation rates in the high-potential cycle test of a half-cell, as a result of which, a loss of only 10% was observed in the effective electrochemical surface area of Pt, even after 10,000 cycles.

  14. Investigation of uranyl phosphite interaction with some amides

    International Nuclear Information System (INIS)

    Avduevskaya, K.A.; Ragulina, N.B.; Rozanov, I.A.; Mukhajlov, Yu.N.; Kanishcheva, A.S.; Grevtseva, T.G.

    1981-01-01

    Uranyl (amide) phosphitocomplexes of [UO 2 HPO 3 H 2 OAA]xH 2 O, [UO 2 HPO 3 (AA) 2 ], [UO 2 HPO 3 H 2 O DMC], [UO 2 HPO 3 H 2 ODMFA], [UO 2 HPO 3 DAMA] and UO 2 HPO 3 x2FAxH 2 O compositions, where AA-acetamide; DMC-N, N-dimetyl carbamide, DMFA-dimetyl formamide; DAMA-diamide of malonic acid; FA-formamide, are separated, identified and investigated. Derivatives of mono substituted uranyl phosphite of UO 2 (H 2 PO 3 ) 2 x2FA and [UO 2 (H 2 PO 3 ) 2 H 2 O]x2TMC composition (where TMC-tetramethyl carbamide), are synthesized. Structures of complexes with DAMA, TMC, DMFA and acid dimethyl-ammonium diphosphitouranylate-(CH 3 ] 2 NH 2 x[UO 2 (HPO 3 ) 3 (H 2 PO 3 )] are investigated [ru

  15. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

    Beitz, J.V.; Williams, C.W.

    1996-01-01

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO 4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO 2 F 2 . Studies on the effect of added LiNO 3 or Na 2 WO 4 ·2H 2 O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF 6 content of WF 6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF 6

  16. ZnO Nanowires Synthesized by Vapor Phase Transport Deposition on Transparent Oxide Substrates

    Directory of Open Access Journals (Sweden)

    Taylor Curtis

    2010-01-01

    Full Text Available Abstract Zinc oxide nanowires have been synthesized without using metal catalyst seed layers on fluorine-doped tin oxide (FTO substrates by a modified vapor phase transport deposition process using a double-tube reactor. The unique reactor configuration creates a Zn-rich vapor environment that facilitates formation and growth of zinc oxide nanoparticles and wires (20–80 nm in diameter, up to 6 μm in length, density <40 nm apart at substrate temperatures down to 300°C. Electron microscopy and other characterization techniques show nanowires with distinct morphologies when grown under different conditions. The effect of reaction parameters including reaction time, temperature, and carrier gas flow rate on the size, morphology, crystalline structure, and density of ZnO nanowires has been investigated. The nanowires grown by this method have a diameter, length, and density appropriate for use in fabricating hybrid polymer/metal oxide nanostructure solar cells. For example, it is preferable to have nanowires no more than 40 nm apart to minimize exciton recombination in polymer solar cells.

  17. Chemistry of the uranyl group

    International Nuclear Information System (INIS)

    Zarli, B.; Dall'olio, G.; Sindellari, L.

    1976-01-01

    Some uranyl complexes with hexamethylphosphoramide (HMPA) and urea were prepared and characterized. The compounds with the former ligand have the general formula UO 2 X 2 .HMPA (where X = (C 2 H 5 ) 2 NCSe 2 - , (C 2 H 5 ) 2 NCS 2 - or CH 3 COO - ). For the acetato derivatives a dimeric acetato-bridged structure is suggested. Some properties of UO 2 (NO 3 ) 2 .2(HMPA) are also described. With the latter ligand, in addition to the complexes UO 2 (NO 3 ) 2 .2urea and [UO 2 (urea) 4 (H 2 0)](NO 3 ) 2 already known, the novel complexes UO 2 (pycrate) 2 .4urea and [UO 2 (CH 3 COO) 2 .urea]sub(n) (where n is probably 2) have been prepared. All attempts to obtain urea complexes of uranyl diethyldithio- or diethyldiselenocarbamate failed and only adducts of unsatisfactory stoichiometry were isolated. (author)

  18. Electrospray ionization of uranyl-citrate complexes

    Science.gov (United States)

    Somogyi, Árpád; Pasilis, Sofie P.; Pemberton, Jeanne E.

    2007-09-01

    Results presented here demonstrate the usefulness of electrospray ionization and gas-phase ion-molecule reactions to predict structural and electronic differences in complex inorganic ions. Electrospray ionization of uranyl citrate solutions generates positively and negatively charged ions that participate in further ion-molecule reactions in 3D ion trap and FT-ICR mass analyzers. Most ions observed are derived from the major solution uranyl-citrate complexes and involve species of {(UO2)2Cit2}2-, (UO2)3Cit2, and {(UO2)3Cit3}3-, where Cit indicates the citrate trianion, C6H5O73-. In a 3D ion trap operated at relatively high pressure, complex adducts containing solvent molecules, alkali and ammonium cations, and nitrate or chloride anions are dominant, and proton/alkali cation (Na+, K+) exchange is observed for up to six exchangeable protons in an excess of alkali cations. Adduct formation in a FT-ICR cell that is operated at lower pressures is less dominant, and direct detection of positive and negative ions of the major solution complexes is possible. Multiply charged ions are also detected, suggesting the presence of uranium in different oxidation states. Changes in uranium oxidation state are detected by He-CID and SORI-CID fragmentation, and certain fragments undergo association reactions in trapping analyzers, forming "exotic" species such as [(UO2)4O3]-, [(UO2)4O4]-, and [(UO2)4O5]-. Ion-molecule reactions with D2O in the FT-ICR cell indicate substantial differences in H/D exchange rate and D2O accommodation for different ion structures and charge states. Most notably, the positively charged ions [H2(UO2)2Cit2(H)]+ and [(UO2)2(Cit)]+ accommodate two and three D2O molecules, respectively, which reflects well the structural differences, i.e., tighter uranyl-citrate coordination in the former ion than in the latter. The corresponding negatively charged ions accommodate zero or two D2O molecules, which can be rationalized using suggested solution phase structures

  19. Pure phase LaFeO3 perovskite with improved surface area synthesized using different routes and its characterization

    International Nuclear Information System (INIS)

    Gosavi, Priti V.; Biniwale, Rajesh B.

    2010-01-01

    Three different wet chemistry routes, namely co-precipitation, combustion and sol-gel methods were used to synthesize LaFeO 3 perovskite with improved surface area. The synthesized perovskite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), Brunauer-Emmett-Teller (BET) nitrogen adsorption, ultraviolet diffused reflectance spectroscopy (UVDRS) and Fourier transform infrared (FTIR) spectroscopy techniques. Improved surface area was observed for all three methods as compared to the previously reported values. The perovskite synthesized using sol-gel method yields comparatively pure, crystalline phase of LaFeO 3 and relatively higher surface area of 16.5 m 2 g -1 and porosity. The material synthesized using co-precipitation method yielded other phases in addition to the targeted phase. The morphology of perovskite synthesized using co-precipitation method was uniform agglomerates. Combustion method yields flakes type morphology and that of sol-gel method was open pore type morphology. The selection of method for perovskite synthesis largely depends on the targeted application and the desired properties of perovskites. The results reported in this study are useful for establishing a simple scalable method for preparation of high surface area LaFeO 3 as compared to solid-oxide method. Further, the typical heating cycle followed for calcinations resulted in relatively high surface area in the case of all three methods.

  20. Phase evolution and infrared transmittance in monophasic VO{sub 2} synthesized by a rapid non-equilibrium process

    Energy Technology Data Exchange (ETDEWEB)

    Rajeswaran, Bharathi, E-mail: rajeswaran.bharathi@gmail.com; Umarji, A.M.

    2017-04-01

    VO{sub 2} displays a semiconducting to metallic (SMT) transition accessible near room temperature. This makes it one of the most sought after materials for electrical and optical switching. But this can be utilized only when the synthesis process yields phase pure VO{sub 2} without other oxides of vanadium. Across the SMT, VO{sub 2} exhibits difference crystal structures with a rich phase behavior of insulating monoclinic M1, M2 and T phases. The objective of this study is to synthesize phase pure VO{sub 2} and to investigate its structural evolution and infrared switching during the transition. In this work, a rapid non-equilibrium process namely Solution Combustion Synthesis (SCS) was employed. The structural phase transition (SPT) of VO{sub 2} nanostructures synthesized by SCS was investigated by in-situ temperature controlled XRD across the SMT. Gaussian curve fittings for measured XRD patterns revealed that competing phases of M1 and R significantly contribute to the observed pattern at every increase in temperature. The powders were further characterized by FTIR, DSC and DC electrical conductivity. These studies show that a sharp SMT was observed at 68–70 °C. Infrared transmittance experiments pinpointed the transition. Carrier density and mobility of VO{sub 2} were calculated. This suggests that this VO{sub 2} thus synthesized displays excellent phase transition behavior and can be utilized in optical and electrical switching. - Highlights: • VO{sub 2} has been synthesized by an easy, rapid, cost-effective, two-step, novel reaction. • High temperature XRD and DSC showed first order phase transition. • IR transmittance showed a decrease in transmittance at high temperatures enabling it to be used for IR sensing.

  1. Thermal analysis studies of ammonium uranyl carbonate

    International Nuclear Information System (INIS)

    Cao Xinsheng; Ma Xuezhong; Wang Fapin; Liu Naixin; Ji Changhong

    1988-01-01

    The simultaneous thermogravimetry and differential thermal analysis of the ammonium uranyl carbonate powder were performed with heat balance in the following atmosphers: Air, Ar and Ar-8%H 2 . The thermogravimetry and differential thermal analysis curves of the ammonium uranyl carbonate powder obtained from different source were reported and discussed

  2. Room-temperature saturated ferroelectric polarization in BiFeO3 ceramics synthesized by rapid liquid phase sintering

    International Nuclear Information System (INIS)

    Wang, Y.P.; Zhou, L.; Zhang, M.F.; Chen, X.Y.; Liu, J.-M.; Liu, Z.G.

    2004-01-01

    Single-phased ferroelectromagnet BiFeO 3 ceramics with high resistivity were synthesized by a rapid liquid phase sintering technique. Saturated ferroelectric hysteresis loops were observed at room temperature in the ceramics sintered at 880 deg. C for 450 s. The spontaneous polarization, remnant polarization, and the coercive field are 8.9 μC/cm 2 , 4.0 μC/cm 2 , and 39 kV/cm, respectively, under an applied field of 100 kV/cm. It is proposed that the formation of Fe 2+ and an oxygen deficiency leading to the higher leakage can be greatly suppressed by the very high heating rate, short sintering period, and liquid phase sintering technique. The latter was also found effective in increasing the density of the ceramics. The sintering technique developed in this work is expected to be useful in synthesizing other ceramics from multivalent or volatile starting materials

  3. Thermodynamics of Uranyl Minerals: Enthalpies of Formation of Uranyl Oxide Hydrates

    International Nuclear Information System (INIS)

    Kubatko, K.; Helean, K.; Navrotsky, A.; Burns, P.C.

    2005-01-01

    The enthalpies of formation of seven uranyl oxide hydrate phases and one uranate have been determined using high-temperature oxide melt solution calorimetry: [(UO 2 ) 4 O(OH) 6 ](H 2 O) 5 , metaschoepite; β-UO 2 (OH) 2 ; CaUO 4 ; Ca(UO 2 ) 6 O 4 (OH) 6 (H 2 O) 8 , becquerelite; Ca(UO 2 ) 4 O 3 (OH) 4 (H 2 O) 2 ; Na(UO 2 )O(OH), clarkeite; Na 2 (UO 2 ) 6 O 4 (OH) 6 (H 2 O) 7 , the sodium analogue of compreignacite and Pb 3 (UO 2 ) 8 O 8 (OH) 6 (H 2 O) 2 , curite. The enthalpy of formation from the binary oxides, ΔH f-ox , at 298 K was calculated for each compound from the respective drop solution enthalpy, ΔH ds . The standard enthalpies of formation from the elements, ΔH f o , at 298 K are -1791.0 ± 3.2, -1536.2 ± 2.8, -2002.0 ± 3.2, -11389.2 ± 13.5, -6653.1 ± 13.8, -1724.7 ± 5.1, -10936.4 ± 14.5 and -13163.2 ± 34.4 kJ mol -1 , respectively. These values are useful in exploring the stability of uranyl oxide hydrates in auxiliary chemical systems, such as those expected in U-contaminated environments

  4. Investigation of uranyl nitrate complexes with trialkylphosphine oxides

    International Nuclear Information System (INIS)

    Kobets, L.V.; Kopashova, I.M.; Dik, T.A.; Volodin, I.A.; Kovalenko, M.A.; Semenij, V.Ya.

    1982-01-01

    Using the methods of vibrational spectroscopy and thermal analysis a number of uranyl complexes with trialkylphosphine oxides of the general formula UO 2 (NO 3 ) 2 x2R 3 PO, where R-C 2 H 5 -C 10 H 21 have been studied. Infrared and Raman spectra are interpreted according to vibration types. Comparison of vibrational spectra of the complexes in solid phase and solutions of organic solvents permitted to find the differences in position and amount of acids responsible for complexing. It is detected that in the series of complexes investigated the strength of uranyl bond with phosphoryl group oxygen practically remains stable, whereas degree of covalence of nitrate groups is observed. The pointed out peculiarities are interpreted proceeding from the presence of bridge nitrate groups in the structure of the complexes. Thermal stability of the complexes is studied, chemism of their decomposition being suggested

  5. Solvent extraction of uranyl nitrate (1962); Extraction du nitrate d'uranyle par solvant (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Talmont, X; Regnaut, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires; Durandet, J; Renault, Ph; Gladel, Y L [Institut Francais du Petrole (IFP), Dept. de Physico-Chimie Appliquee, 92 - Rueil-Malmaison (France)

    1962-07-01

    The transfer of uranyl nitrate from an aqueous acid phase into a solvent (dilute tributylphosphate) is attended by nitric acid transfer. In these conditions, equilibrium data cannot be represented by a plane curve, which complicates the determination of the efficiency of the extractor used, i.e. the calculation of either the number of theoretical plates or the number of transfer units equivalent to the apparatus. The authors are presenting a simple method for estimating the efficiency of a column, based upon either uranium or acid transfer. This method can be used when the profile of uranium and acid concentrations in a phase circulating in the equipment bas been previously determined. On another hand, it enables to study the variation of local efficiency, i.e. the efficiency of different sections of the column. (authors) [French] Le transfert du nitrate d'uranyle d'une phase aqueuse acide dans un solvant (phosphate de tributyle dilue) s'accompagne d'un transfert d'acide nitrique. Dans ces conditions, les donnees d'equilibre ne sont pas representees par une courbe plane, ce qui complique la determination de l'efficacite de l'extracteur utilise, c'est-a-dire le calcul, soit du nombre d'etages theoriques, soit du nombre d'unites de transfert auquel l'appareil est equivalent. Les auteurs presentent une methode simple d'evaluation de l'efficacite d'une colonne basee, soit sur le transfert d'uranium, soit sur celui d'acide. Cette methode est utilisable lorsqu'en a determine au prealable le profil des concentrations en uranium et en acide d'une phase circulant dans l'appareil. Elle permet, d'autre part, d'etudier la variation de l'efficacite locale, c'est-a-dire l'efficacite de differentes sections de la colonne. (auteurs)

  6. Expanding the Library of Uranyl Amide Derivatives: New Complexes Featuring the tert-Butyldimethylsilylamide Ligand.

    Science.gov (United States)

    Pattenaude, Scott A; Coughlin, Ezra J; Collins, Tyler S; Zeller, Matthias; Bart, Suzanne C

    2018-04-16

    New uranyl derivatives featuring the amide ligand, -N(SiHMe 2 ) t Bu, were synthesized and characterized by X-ray crystallography, multinuclear NMR spectroscopy, and absorption spectroscopies. Steric properties of these complexes were also quantified using the computational program Solid-G. The increased basicity of the free ligand -N(SiHMe 2 ) t Bu was demonstrated by direct comparison to -N(SiMe 3 ) 2 , a popular supporting ligand for uranyl. Substitutional lability on a uranyl center was also demonstrated by exchange with the -N(SiMe 3 ) 2 ligand. The increased basicity of this ligand and diverse characterization handles discussed here will make these compounds useful synthons for future reactivity.

  7. Synthesis, X-ray crystallography, thermal studies, spectroscopic and electrochemistry investigations of uranyl Schiff base complexes.

    Science.gov (United States)

    Asadi, Zahra; Shorkaei, Mohammad Ranjkesh

    2013-03-15

    Some tetradentate salen type Schiff bases and their uranyl complexes were synthesized and characterized by UV-Vis, NMR, IR, TG, C.H.N. and X-ray crystallographic studies. From these investigations it is confirmed that a solvent molecule occupied the fifth position of the equatorial plane of the distorted pentagonal bipyramidal structure. Also, the kinetics of complex decomposition by using thermo gravimetric methods (TG) was studied. The thermal decomposition reactions are first order for the studied complexes. To examine the properties of uranyl complexes according to the substitutional groups, we have carried out the electrochemical studies. The electrochemical reactions of uranyl Schiff base complexes in acetonitrile were reversible. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Balanced Photodetection in One-Step Liquid-Phase-Synthesized CsPbBr3 Micro-/Nanoflake Single Crystals.

    Science.gov (United States)

    Zheng, Wei; Xiong, Xufan; Lin, Richeng; Zhang, Zhaojun; Xu, Cunhua; Huang, Feng

    2018-01-17

    Here, we reported a low-cost and high-compatibility one-step liquid-phase synthesis method for synthesizing high-purity CsPbBr 3 micro-/nanoflake single crystals. On the basis of the high-purity CsPbBr 3 , we further prepared a low-dimensional photodetector capable of balanced photodetection, involving both high external quantum efficiency and rapid temporal response, which is barely realized in previously reported low-dimensional photodetectors.

  9. Sorption of uranyl ions on hydrous oxides

    International Nuclear Information System (INIS)

    Gupta, A.R.; Venkataramani, B.

    1988-01-01

    Sorption of uranyl ions on hydrous titanium oxide (HTiO), magnetite (MAG), and hydrous thorium oxide (HThO) has been studied as a function of pH. Hydrous oxides have been characterized by their pH-titration curves, intrinsic dissociation constants (pK ai * ) and point of zero charge (pH pzc ). The fraction of protonated surface hydroxyl groups as well as the surface pH (pH surf ) as a function of solution pH have been computed. The distribution of various hydrolyzed species of uranyl ions with solution pH have been compared with uranyl sorption isotherm on these oxides. Sorption edge in all the cases occurs when free hydroxyl groups are available on the surface and pH surf is sufficiently high to favor the formation of dimer-like species on the surface. A new model for the sorption process, called surface hydrolysis model, which explains these and other features of uranyl sorption on hydrous oxides has been proposed. The model visualizes the sorption process as linking of uranyl ions with two adjacent free surface hydroxyl groups without deprotonation (provided the surface pH is high for the hydrolysis of uranyl ions) and formation of dimer-like structures on the surface. The new model has been successfully applied to the present and other available data on uranyl ion sorption on hydrous oxides. (author)

  10. Morphology and phase transformations of tin oxide nanostructures synthesized by the hydrothermal method in the presence of dicarboxylic acids

    International Nuclear Information System (INIS)

    Zima, Tatyana; Bataev, Ivan

    2016-01-01

    A new approach to the synthesis of non-stoichiometric tin oxide structures with different morphologies and the phase compositions has been evaluated. The nanostructures were synthesized by hydrothermal treatment of the mixtures of dicarboxylic acids ― aminoterephthalic or oxalic ― with nanocrystalline SnO 2 powder, which was obtained via the sol-gel technology. The products were characterized by Raman and IR spectroscopy, SEM, HRTEM, and XRD analysis. It was shown that the controlled addition of a dicarboxylic acid leads not only to a change in the morphology of the nanostructures, but also to SnO 2 –SnO 2 /Sn 3 O 4 –Sn 3 O 4 –SnO phase transformations. A single-phase Sn 3 O 4 in the form of the well-separated hexagonal nanoplates and mixed SnO 2 /Sn 3 O 4 phases in the form of hierarchical flower-like structures were obtained in the presence of organic additives. The effects of concentration, redox activity of the acids and heat treatment on the basic characteristics of the synthesized tin oxide nanostructures and phase transformations in the synthesized materials are discussed. - Graphical abstract: The controlled addition of aminoterephthalic or oxalic acid leads not only to a change in the morphology of the nanostructures, but also to SnO 2 –SnO 2 /Sn 3 O 4 –Sn 3 O 4 –SnO phase transformations. - Highlights: • A new approach to the synthesis of non-stoichiometric tin oxide structures is studied. • Tin oxide structures are synthesized via hydrothermal method with dicarboxylic acids. • Morphology and phase composition are changed with redox activity and dosage of acid. • The redox activity of acid has an effect on ratio of SnO and SnO 2 in crystal structure. • A pure phase Sn 3 O 4 nanoplates and SnO 2 /Sn 3 O 4 hierarchical structures are formed.

  11. Influence of the organic phase property on the extraction of tenoil - trifluoroacetonate uranyl, Annex 6; Prilog 6: Uticaj prirode organske faze na ekstrakciju tenoil - trifluoracetonata uranila

    Energy Technology Data Exchange (ETDEWEB)

    Milic, N; Petruhin, O M; Zolotov, J A [Institute of Nuclear Sciences Boris Kidric, Laboratorija za visoku aktivnost, Vinca, Beograd (Serbia and Montenegro)

    1963-12-15

    This paper describes the study of of uranium (VI) (2.5 10{sup -4}M) extraction from acetate puffer solutions with 0.01 M solution of tenoil trifluoroacetonate in benzene, chloroform, carbon tetrachloride, amyl acetate, cyclohexanon, n-butyl alcohol with the additions of 0.036 M TBP and 2.7 M acetone solution with 0.01 M solution of TTA. It was verified that the extraction depends on the property of the organic phase. Distribution coefficients for uranium when extracted by solvents containing oxygen is higher compared to the distribution coefficients obtained by solvents without oxygen (benzene, chloroform and carbon tetrachloride). TBP cyclohexanon, and acetone additions in the CCl{sub 4} cause more significant increase of distribution coefficients.

  12. Electrochemical behavior of uranyl in anhydrous polar organic media

    Energy Technology Data Exchange (ETDEWEB)

    Burn, Adam G.; Nash, Kenneth L. [Washington State Univ., Pullmann, WA (United States). Dept. of Chemistry

    2017-09-01

    Weak complexes between pentavalent and hexavalent actinyl cations have been reported to exist in acidic, non-complexing high ionic strength aqueous media. Such ''cation-cation complexes'' were first identified in the context of actinide-actinide redox reactions in acidic aqueous media relevant to solvent extraction-based separation systems, hence their characterization is of potential interest for advanced nuclear fuel reprocessing. This chemistry could be relevant to efforts to develop advanced actinide separations based on the upper oxidation states of americium, which are of current interest. In the present study, the chemical behavior of pentavalent uranyl was examined in non-aqueous, aprotic polar organic solvents (propylene carbonate and acetonitrile) to determine whether UO{sub 2}{sup +} cations generated at the reducing working electrode surface would interact with the UO{sub 2}{sup 2+} cations in the bulk phase to form cation-cation complexes in such media. In magnesium perchlorate media, the electrolyte adsorbed onto the working electrode surface and interfered with the uranyl reduction/diffusion process through an ECE (electron transfer/chemical reaction/electron transfer) mechanism. In parallel studies of uranyl redox behavior in tetrabutylammonium hexafluorophosphate solutions, an EC (electron transfer/chemical reaction) mechanism was observed in the cyclic voltammograms. Ultimately, no conclusive electrochemical evidence demonstrated uranyl cation-cation interactions in the non-aqueous, aprotic polar organic solvent solutions, though the results reported do not completely rule out the presence of UO{sub 2}{sup +}.UO{sub 2}{sup 2+} complexes.

  13. Mesomorphic phase behaviour of low molar mass PEP-PDMS diblock copolymers synthesized by anionic polymerization

    International Nuclear Information System (INIS)

    Vigild, M.E.

    1997-10-01

    The phase behaviour of low molar mass poly(ethylene-alt-propylene) -poly(dimethylsiloxane) (PEP-PDMS) is investigated in this thesis by the combination of dynamical mechanical spectroscopy (rheology) to measure phase transition temperatures, and small-angle x-ray scattering to identify the morphology of encountered phases. Samples of PEP-PDMS in the range of 0.2-0.7 in volume fraction of PEP are studied. This diblock copolymer system exhibits the three classical phases of lamellar sandwich structure (LAM), hexagonally packed cylinders (HEX), and spheres arranged on a body centered cubic lattice (BCC). Furthermore the gyroid phase (Ia3d symmetry) of two interpenetrating networks was also identified as a stable phase of the PEP-PDMS system. Time resolved measurements of small-angle neutron scattering in tandem with simultaneous in-situ rheological measurements are performed on samples showing transitions between different ordered phases. The identification of especially the BCC and gyroid phases from scattering experiments is treated. By performing mesoscopic crystallographic measurements using a custom built goniometer it was unambiguously shown that the application of shear to an unoriented powder-like sample introduces uniaxial orientation of the gyroid phase. The orientation of the ordered phase is otherwise random, causing a two-dimensional powder. Finally this dissertation presents a discussion of relevant parameters for the description of diblock copolymer phase behaviour together with descriptions of anionic polymerization for the synthesis of copolymers, and various experimental techniques for the characterization of diblocks. (au)

  14. Extraction of rare earth metals (3) from aqueous solutions containing thorium and uranyl nitrates

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kopyrin, A.A.; Berinskij, A.E.; Keskinov, V.A.

    2000-01-01

    Isotherms of extraction of rare earth metals (3) from aqueous solutions containing thorium and uranyl nitrates by solutions of tributylphosphate (TBP) and diisooctylmethylphosphonate (DIOMP) in kerosene at 298.15 Deg C and pH 1 are presented. Equations for description of interphase distribution of components of the systems considered are suggested. These equations describe distribution of components adequately in the systems of thorium nitrate (uranyl nitrate) - rare earth nitrates - (TBP, DIOMP) in the case of wide variation of phase compositions. Dependences of separation factors on composition of aqueous phase are considered [ru

  15. Design and Characterization of a 5.2 GHz/2.4 GHz Fractional- Frequency Synthesizer for Low-Phase Noise Performance

    Directory of Open Access Journals (Sweden)

    Dai Foster F

    2006-01-01

    Full Text Available This paper presents a complete noise analysis of a -based fractional- phase-locked loop (PLL based frequency synthesizer. Rigorous analytical and empirical formulas have been given to model various phase noise sources and spurious components and to predict their impact on the overall synthesizer noise performance. These formulas have been applied to an integrated multiband WLAN frequency synthesizer RFIC to demonstrate noise minimization through judicious choice of loop parameters. Finally, predicted and measured phase jitter showed good agreement. For an LO frequency of 4.3 GHz, predicted and measured phase noise was rms and rms, respectively.

  16. Design and Characterization of a 5.2 GHz/2.4 GHz ΣΔ Fractional- N Frequency Synthesizer for Low-Phase Noise Performance

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available This paper presents a complete noise analysis of a ΣΔ -based fractional- N phase-locked loop (PLL based frequency synthesizer. Rigorous analytical and empirical formulas have been given to model various phase noise sources and spurious components and to predict their impact on the overall synthesizer noise performance. These formulas have been applied to an integrated multiband WLAN frequency synthesizer RFIC to demonstrate noise minimization through judicious choice of loop parameters. Finally, predicted and measured phase jitter showed good agreement. For an LO frequency of 4.3 GHz, predicted and measured phase noise was 0.50 ° rms and 0.535 ° rms, respectively.

  17. Effects of cement organic additives on the adsorption of uranyl ions on calcium silicate hydrate phases: experimental determination and computational molecular modelling

    International Nuclear Information System (INIS)

    Androniuk, Iuliia

    2017-01-01

    Cementitious materials are extensively used in the design and construction of radioactive waste repositories. One of the ways to enhance their performance is to introduce organic admixtures into the cement structure. However, the presence of organics in the pore water may affect the radionuclide mobility: organic molecules can form water-soluble complexes and compete for sorption sites. This work was designed to get detailed understanding of the mechanisms of such interactions on the molecular level. The model system has three components. First, pure C-S-H phases with different Ca/Si ratios were chosen as a cement model. Secondly, gluconate (a simple well-described molecule) is selected as a good starting organic additive model to probe the interaction mechanisms on the molecular scale. A more complex system involving poly-carboxylate super-plasticizer (PCE) was also tested. The third, U(VI), is a representative of the actinide radionuclide series. The development of description of the effects of organics for radioactive waste disposal applications was the primary objective of this work. The study of binary systems provides reference data for the investigation of more complex ternary (C-S-H/organic/U(VI)). The interactions are studied by means of both experimental and computational molecular modelling techniques. Data on sorption and desorption kinetics and isotherms for additives and for U(VI) on C-S-H are acquired in this work. In parallel, atomistic models are developed for the interfaces of interest. Structural, energetic, and dynamic aspects of the sorption processes on surface of cement are quantitatively modeled by molecular dynamics technique. (author)

  18. Photoelectrochemical properties of orthorhombic and metastable phase SnS nanocrystals synthesized by a facile colloidal method

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Po-Chia [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Huang, Jow-Lay [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan, ROC (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan, ROC (China); Wang, Sheng-Chang; Shaikh, Muhammad Omar [Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan, ROC (China); Lin, Chia-Yu [Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

    2015-12-01

    SnS of orthorhombic (OR) and metastable (SnS) phases were synthesized by using a simple and facile colloidal method. The tin precursor was synthesized using tin oxide (SnO) and oleic acid (OA), while the sulfur precursor was prepared using sulfur powder (S) and oleyamine (OLA). The sulfur precursor was injected into the tin precursor and the prepared SnS nanocrystals were precipitated at a final reaction temperature of 180 °C. The results show that hexamethyldisilazane (HMDS) can be successfully used as a surfactant to synthesize monodisperse 20 nm metastable SnS nanoparticles, while OR phase SnS nanosheets were obtained without HMDS. The direct bandgap observed for the metastable SnS phase is higher (1.66 eV) as compared to the OR phase (1.46 eV). The large blueshift in the direct bandgap of metastable SnS is caused by the difference in crystal structure. The blueshift in the direct band gap value for OR-SnS could be explained by quantum confinement in two dimensions in the very thin nanosheets. SnS thin films used as a photo anode in a photoelectrochemical (PEC) cell were prepared by spin coating on the fluorine-doped tin oxide (FTO) substrates. The photocurrent density of the SnS (metastable SnS)/FTO and SnS (OR)/FTO are 191.8 μA/cm{sup 2} and 57.61 μA/cm{sup 2} at an applied voltage of − 1 V at 150 W, respectively. These narrow band gap and low cost nanocrystals can be used for applications in future optoelectronic devices. - Highlights: • A facile method to synthesize two different phases of SnS having different morphological and optical properties. • The phases and morphologies of SnS nanocrystal can be controlled by adding capping surfactant hexamethyldisilazane (HMDS). • As we know, this is the first metastable SnS photoanode for application in a photoelectrochemical cell.

  19. A microscopic study of the action of uranyl acetate on the erythrocyte at varying molarity and toxicity

    International Nuclear Information System (INIS)

    Wyatt, J.H.

    1977-03-01

    Phase contrast and dark field microphotographs were made to record variation of the shape and size changes seen when human erythrocytes are exposed in a number of ways to uranyl acetate in vitro. The degree of hemolysis produced by varying the toxicity of the uranyl acetate solutions was measured, and the results are discussed with particular reference to the possible influence of pH. (author)

  20. Mesomorphic phase behaviour of low molar mass PEP-PDMS diblock copolymers synthesized by anionic polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Vigild, M.E.

    1997-10-01

    The phase behaviour of low molar mass poly(ethylene-alt-propylene) -poly(dimethylsiloxane) (PEP-PDMS) is investigated in this thesis by the combination of dynamical mechanical spectroscopy (rheology) to measure phase transition temperatures, and small-angle x-ray scattering to identify the morphology of encountered phases. Samples of PEP-PDMS in the range of 0.2-0.7 in volume fraction of PEP are studied. This diblock copolymer system exhibits the three classical phases of lamellar sandwich structure (LAM), hexagonally packed cylinders (HEX), and spheres arranged on a body centered cubic lattice (BCC). Furthermore the gyroid phase (Ia3d symmetry) of two interpenetrating networks was also identified as a stable phase of the PEP-PDMS system. Time resolved measurements of small-angle neutron scattering in tandem with simultaneous in-situ rheological measurements are performed on samples showing transitions between different ordered phases. The identification of especially the BCC and gyroid phases from scattering experiments is treated. By performing mesoscopic crystallographic measurements using a custom built goniometer it was unambiguously shown that the application of shear to an unoriented powder-like sample introduces uniaxial orientation of the gyroid phase. The orientation of the ordered phase is otherwise random, causing a two-dimensional powder. Finally this dissertation presents a discussion of relevant parameters for the description of diblock copolymer phase behaviour together with descriptions of anionic polymerization for the synthesis of copolymers, and various experimental techniques for the characterization of diblocks. (au). 9 tabs., 40 ills., 81 refs.

  1. Phase transformations of high-purity PbI{sub 2} nanoparticles synthesized from lead-acid accumulator anodes

    Energy Technology Data Exchange (ETDEWEB)

    Malevu, T.D., E-mail: malevutd@ufs.ac.za; Ocaya, R.O.; Tshabalala, K.G.

    2016-09-01

    High-purity hexagonal lead iodide nanoparticles have been synthesized from a depleted sealed lead acid battery anode. The synthesized product was found to consist of the rare 6R polytype form of PbI{sub 2} that is thought to have good potential in photovoltaic applications. We investigate the effects of annealing time and post-melting temperature on the structure and optical properties using 1.5418 Å CuKα radiation. Photoluminescence measurements were done under 150 W/221 nm wavelength xenon excitation. Phase transformation was observed through XRD peaks when annealing time increased from 0.5–5 h. The nanoparticle grain size and inter-planar distance appeared to be independent of annealing time. PL measurements show three broad peaks in a range of 400 nm to 700 nm that are attributed to excitonic, donor–acceptor pair and luminescence bands from the deep levels.

  2. The dehydration of uranyl nitrate hexahydrate

    International Nuclear Information System (INIS)

    Badalov, A.; Kamalov, D.D.; Khamidov, B.O.; Mirsaidov, I.U.; Eshbekov, N.R.

    2010-01-01

    Present article is devoted to study of dehydration process of uranyl nitrate hexahydrate. The dehydration process of uranyl nitrate hexahydrate was studied by means of tensimeter method with membrane zero-manometer. The research was carried out under equilibrium conditions. It was defined that in studied temperature ranges (300-450 K) the dehydration process of UO_2(NO_3)_2 has a three stage character.

  3. Selectivity in ligand binding to uranyl compounds: A synthetic, structural, thermodynamic and computational study

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, John [Univ. of California, Berkeley, CA (United States)

    2015-01-21

    The uranyl cation (UO₂²⁺) is the most abundant form of uranium on the planet. It is estimated that 4.5 billion tons of uranium in this form exist in sea water. The ability to bind and extract the uranyl cation from aqueous solution while separating it from other elements would provide a limitless source of nuclear fuel. A large body of research concerns the selective recognition and extraction of uranyl. A stable molecule, the cation has a linear O=U=O geometry. The short U-O bonds (1.78 Å) arise from the combination of uranium 5f/6d and oxygen 2p orbitals. Due to the oxygen moieties being multiply bonded, these sites were not thought to be basic enough for Lewis acidic coordination to be a viable approach to sequestration. The goal of this research is thus to broaden the coordination chemistry of the uranyl ion by studying new ligand systems via synthetic, structural, thermodynamic and computational methods. It is anticipated that this fundamental science will find use beyond actinide separation technologies in areas such as nuclear waste remediation and nuclear materials. The focus of this study is to synthesize uranyl complexes incorporating amidinate and guanidinate ligands. Both synthetic and computational methods are used to investigate novel equatorial ligand coordination and how this affects the basicity of the oxo ligands. Such an understanding will later apply to designing ligands incorporating functionalities that can bind uranyl both equatorially and axially for highly selective sequestration. Efficient and durable chromatography supports for lanthanide separation will be generated by (1) identifying robust peptoid-based ligands capable of binding different lanthanides with variable affinities, and (2) developing practical synthetic methods for the attachment of these ligands to Dowex ion exchange resins.

  4. Selectivity in ligand binding to uranyl compounds: A synthetic, structural, thermodynamic and computational study

    International Nuclear Information System (INIS)

    Arnold, John

    2015-01-01

    The uranyl cation (UO 2 2+ ) is the most abundant form of uranium on the planet. It is estimated that 4.5 billion tons of uranium in this form exist in sea water. The ability to bind and extract the uranyl cation from aqueous solution while separating it from other elements would provide a limitless source of nuclear fuel. A large body of research concerns the selective recognition and extraction of uranyl. A stable molecule, the cation has a linear O=U=O geometry. The short U-O bonds (1.78 Å) arise from the combination of uranium 5f/6d and oxygen 2p orbitals. Due to the oxygen moieties being multiply bonded, these sites were not thought to be basic enough for Lewis acidic coordination to be a viable approach to sequestration. The goal of this research is thus to broaden the coordination chemistry of the uranyl ion by studying new ligand systems via synthetic, structural, thermodynamic and computational methods. It is anticipated that this fundamental science will find use beyond actinide separation technologies in areas such as nuclear waste remediation and nuclear materials. The focus of this study is to synthesize uranyl complexes incorporating amidinate and guanidinate ligands. Both synthetic and computational methods are used to investigate novel equatorial ligand coordination and how this affects the basicity of the oxo ligands. Such an understanding will later apply to designing ligands incorporating functionalities that can bind uranyl both equatorially and axially for highly selective sequestration. Efficient and durable chromatography supports for lanthanide separation will be generated by (1) identifying robust peptoid-based ligands capable of binding different lanthanides with variable affinities, and (2) developing practical synthetic methods for the attachment of these ligands to Dowex ion exchange resins.

  5. Enantioselective syntheses and biological studies of aeruginosin 298-A and its analogs: application of catalytic asymmetric phase-transfer reaction.

    Science.gov (United States)

    Fukuta, Yuhei; Ohshima, Takashi; Gnanadesikan, Vijay; Shibuguchi, Tomoyuki; Nemoto, Tetsuhiro; Kisugi, Takaya; Okino, Tatsufumi; Shibasaki, Masakatsu

    2004-04-13

    Aeruginosin 298-A was isolated from the freshwater cyanobacterium Microcystis aeruginosa (NIES-298) and is an equipotent thrombin and trypsin inhibitor. A variety of analogs were synthesized to gain insight into the structure-activity relations. We developed a versatile synthetic process for aeruginosin 298-A as well as several attractive analogs, in which all stereocenters were controlled by catalytic asymmetric phase-transfer reaction promoted by two-center asymmetric catalysts and catalytic asymmetric epoxidation promoted by a lanthanide-BINOL complex. Furthermore, serine protease inhibitory activities of aeruginosin 298-A and its analogs were examined.

  6. Thermodynamics of Uranyl Minerals: Enthalpies of Formation of Uranyl Oxide Hydrates

    Energy Technology Data Exchange (ETDEWEB)

    K. Kubatko; K. Helean; A. Navrotsky; P.C. Burns

    2005-05-11

    The enthalpies of formation of seven uranyl oxide hydrate phases and one uranate have been determined using high-temperature oxide melt solution calorimetry: [(UO{sub 2}){sub 4}O(OH){sub 6}](H{sub 2}O){sub 5}, metaschoepite; {beta}-UO{sub 2}(OH){sub 2}; CaUO{sub 4}; Ca(UO{sub 2}){sub 6}O{sub 4}(OH){sub 6}(H{sub 2}O){sub 8}, becquerelite; Ca(UO{sub 2}){sub 4}O{sub 3}(OH){sub 4}(H{sub 2}O){sub 2}; Na(UO{sub 2})O(OH), clarkeite; Na{sub 2}(UO{sub 2}){sub 6}O{sub 4}(OH){sub 6}(H{sub 2}O){sub 7}, the sodium analogue of compreignacite and Pb{sub 3}(UO{sub 2}){sub 8}O{sub 8}(OH){sub 6}(H{sub 2}O){sub 2}, curite. The enthalpy of formation from the binary oxides, {Delta}H{sub f-ox}, at 298 K was calculated for each compound from the respective drop solution enthalpy, {Delta}H{sub ds}. The standard enthalpies of formation from the elements, {Delta}H{sub f}{sup o}, at 298 K are -1791.0 {+-} 3.2, -1536.2 {+-} 2.8, -2002.0 {+-} 3.2, -11389.2 {+-} 13.5, -6653.1 {+-} 13.8, -1724.7 {+-} 5.1, -10936.4 {+-} 14.5 and -13163.2 {+-} 34.4 kJ mol{sup -1}, respectively. These values are useful in exploring the stability of uranyl oxide hydrates in auxiliary chemical systems, such as those expected in U-contaminated environments.

  7. FEBEX: Full-Scale engineered barriers experiment in crystalline host-rock: preoperational phase. Synthesized report

    International Nuclear Information System (INIS)

    1997-01-01

    The FEBEX project is being cofinanced by the EC under contract F 14WCT950006. In addition to the EC, seven partners from three countries of the EU. (France, Germany, and Spain) as well as one from EFTA (Switzerland) are participating in the project. ENRESA is the coordinating partner with NAGRA assisting in coordinating some aspects. The project consists of two large-scale tests and a series of complimentary laboratory tests. The work is being executed by the following organizations: CIEMAT, AITEMIN, UP-DIT (CIMNE), ULC, CSIC-Zaidin, and UPM (SPAIN) ANDRA and G.3S (FRANCE) GRS (GERMANY). This report includes a synthesized description of the experiment from its conception through the installation of the two large-scale tests (from the middle of 1994 to the beginning of 1997, preoperation stage). The experiment is described in detail in a series of specific reports. (Author)

  8. Structural phase transformations in KYF4:Er3+ nanoparticles synthesized by hydrothermal method for upconversion applications

    Science.gov (United States)

    Yamini, S.; Priya, P. Sakthi; Gunaseelan, M.; Senthilselvan, J.

    2017-05-01

    KYF4:10%Er3+ upconversion nanoparticles was synthesized by hydrothermal method with potassium hydroxides (KOH) as precursor. Prepared samples were calcined at 600 °C using double crucible method. XRD patterns of as prepared KYF4 and KYF4:Er3+ samples confirm the tetragonal structure, which is well matched with the standard data. Surface morphology is recorded for 600 °C calcined samples using High resolution scanning electron microscopy (HRSEM) shows spheroidal shape with particle sizes of ˜80 nm. From UV-Visible and EDX spectroscopy presence of Er3+ in KYF4:10%Er3+ is confirmed. The prepared KYF4:10%Er3+ can be used to improve efficiency of solar cells, display devices and fiber optical telecommunication applications.

  9. Crystallization Mechanism and Phase Transition Properties of W-doped VO2 Synthesized by Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    LI Yao

    2017-11-01

    Full Text Available VO2 sol was firstly prepared using vanadyl sulfate as a vanadium source by precipitation-peptization method. Then tungsten(W doping vanadium dioxide(W-VO2 was prepared by hydrothermal crystallization of prepared sol with the presence of ammonium metatungstate. The morphologies, crystal structure of the as-prepared samples and phase transition properties were studied by X-ray diffraction(XRD, field emission scanning electron microscope(FESEMand differential scanning calorimetry(DSC analysis. The results indicate that rod-like W-VO2(B crystal with length of 1-2μm and radius of 100-200nm is firstly formed during hydrothermal treatment for 4-48h at 280℃, then the rod-like crystal dissolves gradually and sheet-like or snowflake-like crystal is formed with the phase transition from W-VO2(B to W-VO2(M and eventually, the W-VO2(M crystals can further grow up while the W-VO2(B gradually dissolves; the phase transition temperature of VO2 decreases with the increase in W doping content, and the phase transition temperature of W-VO2(M reduces to about 28℃ when the nominal dopant concentration is 6.0%(atom fraction.The "nucleation-growth-transformation-ripening" mechanism is proposed as the formation mechanism based on the hydrothermal crystallization and morphological evolution process of W-VO2(M.

  10. Solid solution and amorphous phase in Ti–Nb–Ta–Mn systems synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzman, P. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Parra, C. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Bejar, L. [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Morelia C.P. 58000, Michoacán (Mexico); Medina, A. [Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, C.P. 58000, Michoacán (Mexico); Guzman, D. [Departamento de Metalurgia, Universidad de Atacama, Av. España 485, Copiapó (Chile)

    2016-06-15

    This work discusses the formation of Ti–30Nb–13Ta–xMn (x: 2, 4 and 6 wt%) solid solution by mechanical alloying using a shaker mill. A solid solution was formed after 15 h of milling and an amorphous phase was formed after 30 h of milling, according to X-ray diffraction results. Disappearance of strongest X-ray diffraction peaks of Nb, Ta and Mn indicated the formation of solid solution, while, X-ray diffraction patterns of powders milled for 30 h showed an amorphous hump with crystalline peaks in the angular range of 35–45° in 2θ. TEM image analysis showed the presence of nanocrystalline intermetallic compounds embedded in an amorphous matrix. Mn{sub 2}Ti, MnTi and NbTi{sub 4} intermetallic compounds were detected and revealed crystallites with size ranging from 3 to 20 nm. The Gibbs free energy for the formation of solid solution and amorphous phase of three ternary systems (Ti–Nb–Ta, Ti–Nb–Mn and Ti–Ta–Mn) was calculated using extended Miedema's model. Experimental and thermodynamic data confirmed that solid solution was first formed in the alloy with 6wt% Mn followed by the formation of an amorphous phase as milling time increases. The presence of Mn promoted the formation of amorphous phase because the atomic radius difference between Mn with Ti, Nb and Ta. - Highlights: • Thermodynamics analysis of extension of solid solution of the Ti–Nb–Ta–Mn system. • Formation of amorphous phase and intermetallic compounds were observed. • Nanocrystalline intermetallic compounds were formed with the sizes between 3 and 20 nm.

  11. Self-assembly of gas-phase synthesized magnesium nanoparticles on room temperature substrates

    International Nuclear Information System (INIS)

    Venturi, F; Calizzi, M; Pasquini, L; Bals, S; Perkisas, T

    2015-01-01

    Magnesium nanoparticles (NPs) with initial size in the 10–50 nm range were synthesized by inert gas condensation under helium flow and deposited on room temperature substrates. The morphology and crystal structure of the NPs ensemble were investigated as a function of the deposition time by complementary electron microscopy techniques, including high resolution imaging and chemical mapping. With increasing amount of material, strong coarsening phenomena were observed at room temperature: small NPs disappeared while large faceted NPs developed, leading to a 5-fold increase of the average NPs size within a few minutes. The extent of coarsening and the final morphology depended also on the nature of the substrate. Furthermore, large single-crystal NPs were seen to arise from the self-organization of primary NPs units, providing a mechanism for crystal growth. The dynamics of the self-assembly process involves the basic steps of NPs sticking, diffusion on substrate, coordinated rotation and attachment/coalescence. Key features are the surface energy anisotropy, reflected by the faceted shape of the NPs, and the low melting point of the material. The observed phenomena have strong implications in relation to the synthesis and stability of nanostructures based on Mg or other elements with similar features. (paper)

  12. Microporous uranyl chromates successively formed by evaporation from acidic solution

    Energy Technology Data Exchange (ETDEWEB)

    Siidra, Oleg I.; Nazarchuk, Evgeny V.; Bocharov, Sergey N.; Kayukov, Roman A. [St. Petersburg State Univ. (Russian Federation). Dept. of Crystallography; Depmeier, Wulf [Kiel Univ. (Germany). Inst. fuer Geowissenschaften

    2018-04-01

    The first microporous framework structures containing uranium and chromium have been synthesized and characterized. Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O){sub 2}](H{sub 2}O){sub 3} (1) was crystallized from uranyl chromate solution by evaporation. Further evaporation led to increased viscosity of the solution and overgrowing of Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}(H{sub 2}O)](H{sub 2}O) (2) on the crystals of 1. With respect to 1, the framework of 2 is partially dehydrated. Both frameworks differ compositionally by only one water molecule, but this seemingly small difference affects significantly the pore size and overall structural topology of the frameworks, which present very different flexibility of the U-O-Cr links. These are rigid in the pillared framework of 1, in contrast to 2 where the U-O-Cr angles range from 126.3 to 168.2 , reflecting the substantial flexibility of Cr-O-U connections which make them comparable to the corresponding Mo-O-U links in uranyl molybdates.

  13. Preparation and physicochemical characterization of anionic uranyl. beta. -ketoenolates

    Energy Technology Data Exchange (ETDEWEB)

    Marangoni, G; Paolucci, G [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi; Graziani, R; Celon, E

    1978-01-01

    New classes of anionic uranyl ..beta..-ketoenolates of formula (UO/sub 2/L/sub 2/X)/sup -/ (where L = 1,3-diphenylpropane-1,3-dionate (dppd), 4,4,4-trifluoro-1-phenylbutane-1,3-dionate (tfpbd), or 1-phenylbutane-1,3-dionate (pbd); X = Cl/sup -/, Br/sup -/, I/sup -/, (NO/sub 3/)/sup -/, (O/sub 2/CMe)/sup -/, or (NCS)/sup -/) and (L/sub 2/O/sub 2/U(..mu..-X) UO/sub 2/L/sub 2/)/sup -/ (where X = F/sup -/, and also Cl/sup -/ only in the case of L = dppd) have been synthesized and characterized by a number of physical measurements. The different ability of the various anionic ligands to enter into the co-ordination sphere of the uranyl ion, their potentially different bonding modes, and the possible correlations between physical parameters and the nature of either the chelate substituents or the anionic ligand are discussed.

  14. Chevrel phases superconductive and ultrafine powders synthesis and characterization; Synthese et caracterisation de poudres ultrafines supraconductrices de phases de Chevrel

    Energy Technology Data Exchange (ETDEWEB)

    Even-Boudjada, S

    1994-12-01

    This work deals with the Chevrel phases superconductive and ultrafine powders synthesis and characterization. The first part of this study presents some new way of synthesis (precipitation, coprecipitation) of Chevrel phases precursors powders (PbS, SnS, MoS{sub 2}) and their characterizations (X-ray fluorescence analysis, ICP mass spectroscopy, scanning electron microscopy, transmission electron microscopy and laser granulometry). These new synthesis methods lead to quasi spherical morphology grains and very weak size grains (0.2 to 0.5 {mu}m) whereas the chemical preparation from the solid state elements gives very different morphology grains (small plates) with a size of 1 to 20 {mu}m. In the second part is shown the interest of the binary Mo{sub 6} S{sub 8} as precursor in the synthesis of ternary superconductive phases (Li, Ni, Cu, Pb). The last part presents the formation reaction of the phase PbMo{sub 6} S{sub 8} and its main chemical and physical properties. Thus some calorimetric measures associated with X-ray diffraction analysis have been realized and have allowed to understand the different reactions occurring during the PbMo{sub 6}S{sub 8} synthesis. (O.L.). 100 refs., figs., tabs.

  15. Photochemical reduction of uranyl nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Duerksen, W.K.

    1993-10-20

    The photochemical reduction of uranyl nitrate solutions to tetravalent uranium was investigated as a means of producing uranium dioxide feed for the saltless direct oxide reduction (SDOR) process. At high uranium concentrations, reoxidation of U{sup +4} occurs rapidly. The kinetics of the nitric oxidation of tetravalent uranium depend on the concentrations of hydrogen ion, nitrate ion, nitrous acid, and tetravalent uranium in the same manner as was reported elsewhere for the nitrate oxidation of PU{sup +3}. Reaction rate data were successfully correlated with a mechanism in which nitrogen dioxide is the reactive intermediate. Addition of a nitrous acid scavenger suppresses the reoxidation reaction. An immersion reactor employing a mercury vapor lamp gave reduction times fast enough for routine production usage. Precipitation techniques for conversion of aqueous U(NO{sub 3}){sub 4} to hydrous UO{sub 2} were evaluated. Prolonged dewatering times tended to make the process time consuming. Use of 3- to 4-M aqueous NaOH gave the best dewatering times observed. Reoxidation of the UO{sub 2} by water of hydration was encountered, which required the drying process to be carried out under a reducing atmosphere.

  16. Metal complex derivatives of hydrogen uranyl phosphate

    International Nuclear Information System (INIS)

    Grohol, D.; Blinn, E.L.

    1994-01-01

    Derivatives of hydrogen uranyl phosphate were prepared by incorporating transition metal complexes into the uranyl phosphate matrix. The transition metal complexes employed include bis(ethylenediamine)copper(II), bis(1,3-propanediamine)copper(II) chloride, (triethylenetetramine)copper(II), (1,4,8,11-tetraazacyclotetradecane)copper(II), (1,4,8,12-tetraazacyclopentadecane)copper(II), (1,4,8,11-tetraazacyclotetradecane)nickel(II) chloride, (triethylenetetramine)nickel(II) and others. The chemical analyses of these derivatives indicated that the incorporation of the transition metal complexes into the uranyl phosphate matrix via ion exchange was not stoichiometric. The extent of ion exchange is dependent on the size and structure of the transition metal complex. All complexes were characterized by X-ray powder diffractometry, electronic and infrared spectra, thermal analyses and chemical analysis. An attempt was made to correlate the degree of quenching of the luminescence of the uranyl ion to the spacing between the uranyl phosphate layers in the derivatives

  17. Study of the structure and phase composition of nanocrystalline silicon oxynitride films synthesized by ICP-CVD

    International Nuclear Information System (INIS)

    Fainer, N.I.; Kosinova, M.L.; Maximovsky, E.A.; Rumyantsev, Yu.M.; Kuznetsov, F.A.; Kesler, V.G.; Kirienko, V.V.

    2005-01-01

    Thin nanocrystalline silicon oxynitride films were synthesized for the first time at low temperatures (373-750 K) by inductively coupled plasma chemical vapor deposition (ICP-CVD) using gas mixture of oxygen and hexamethyldisilazane Si 2 NH(CH 3 ) 6 (HMDS) as precursors. Single crystal Si (1 0 0) wafers 100 mm in diameter were used as substrates. Physicochemical properties of the thin films were examined using ellipsometry, IR spectroscopy, Auger electron and X-ray photoelectron spectroscopy and XRD using synchrotron radiation (SR). The studies of the phase composition of nanocrystalline films of silicon oxynitride showed that in the case of oxygen excess in the initial gas mixture, they contain a mixture of hexagonal phases: h-SiO 2 and α-Si 3 N 4 . These phases consist of oriented nanocrystals of 2-3 nm size. In case of decrease of oxygen concentration in the initial gas mixture, the fraction of the α-Si 3 N 4 phase increases

  18. Study of the structure and phase composition of nanocrystalline silicon oxynitride films synthesized by ICP-CVD

    Energy Technology Data Exchange (ETDEWEB)

    Fainer, N.I. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation)]. E-mail: nadezhda@che.nsk.su; Kosinova, M.L. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation); Maximovsky, E.A. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation); Rumyantsev, Yu.M. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation); Kuznetsov, F.A. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation); Kesler, V.G. [Institute of Semiconductor Physics SB RAS, Acad. Lavrentjev pr., 13, Novosibirsk 630090 (Russian Federation); Kirienko, V.V. [Institute of Semiconductor Physics SB RAS, Acad. Lavrentjev pr., 13, Novosibirsk 630090 (Russian Federation)

    2005-05-01

    Thin nanocrystalline silicon oxynitride films were synthesized for the first time at low temperatures (373-750 K) by inductively coupled plasma chemical vapor deposition (ICP-CVD) using gas mixture of oxygen and hexamethyldisilazane Si{sub 2}NH(CH{sub 3}){sub 6} (HMDS) as precursors. Single crystal Si (1 0 0) wafers 100 mm in diameter were used as substrates. Physicochemical properties of the thin films were examined using ellipsometry, IR spectroscopy, Auger electron and X-ray photoelectron spectroscopy and XRD using synchrotron radiation (SR). The studies of the phase composition of nanocrystalline films of silicon oxynitride showed that in the case of oxygen excess in the initial gas mixture, they contain a mixture of hexagonal phases: h-SiO{sub 2} and {alpha}-Si{sub 3}N{sub 4}. These phases consist of oriented nanocrystals of 2-3 nm size. In case of decrease of oxygen concentration in the initial gas mixture, the fraction of the {alpha}-Si{sub 3}N{sub 4} phase increases.

  19. Rapid hydrothermal route to synthesize cubic-phase gadolinium oxide nanorods

    International Nuclear Information System (INIS)

    Hazarika, Samiran; Paul, Nibedita; Mohanta, Dambarudhar

    2014-01-01

    An inexpensive fabrication route and growth mechanism is being reported for obtaining quality gadolinium oxide ( Gd 2 O 3 ) nanoscale rods. The elongated nanoscale systems, as produced via a hydrothermal process, were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), optical absorption spectroscopy, photoluminescence (PL) spectroscopy, Raman spectroscopy and magnetic hysteresis measurements. XRD patterns of the nanorods, as-prepared from independent precursors of different pH, depict a cubic crystal phase and an average crystallite size of 5-6.5 nm. As revealed from HRTEM micrographs, diameter of the nanorods prepared at pH = 13.3 (∼7 nm) was much smaller than the rods prepared at pH = 10.8 (∼19 nm). However, the aspect ratio was more than double in the former case than the latter case. PL response was found to be dominated by defect mediated emissions, whereas Raman spectrum of a given specimen (pH = 10.8) has revealed characteristic F g + A g modes of cubic phase of Gd 2 O 3 nanorods, apart from other independent modes. Furthermore, M ∼ H plot of the nanorod system (pH = 10.8) exhibited slight departure from the ideal superparamagnetic behaviour, with low remanence and coercive field values. The exploitation of one-dimensional Gd 2 O 3 nanorods have immense potential in the production of advanced contrast agents, smart drives and also in making novel ferrofluids of technological relevance. (author)

  20. Formation of polycrystalline MgB2 synthesized by powder in sealed tube method with different initial boron phase

    Science.gov (United States)

    Yudanto, Sigit Dwi; Imaduddin, Agung; Kurniawan, Budhy; Manaf, Azwar

    2018-04-01

    Magnesium diboride, MgB2 is a new high critical temperature superconductor that discovered in the beginning of the 21st century. The MgB2 has a simple crystal structure and a high critical temperature, which can be manufactured in several forms like thin films, tapes, wires including bulk in the large scale. For that reason, the MgB2 has good prospects for various applications in the field of electronic devices. In the current work, we have explored the synthesis of MgB2 polycrystalline using powder in a sealed tube method. Different initial boron phase for the synthesized of MgB2 polycrystalline were used. These were, in addition to magnesium powders, crystalline boron, amorphous boron and combination both of them were respectively fitted in the synthesis. The raw materials were mixed in a stoichiometric ratio of Mg: B=1:2, ground using agate mortar, packed into stainless steel SS304. The pack was then sintered at temperature of 800°C for 2 hours in air atmosphere. Phase formation of MgB2 polycrystalline in difference of initial boron phase was characterized using XRD and SEM. Referring to the diffraction pattern and microstructure observation, MgB2 polycrystalline was formed, and the formation was effective when using the crystalline Mg and fully amorphous B as the raw materials. The critical temperature of the specimen was evaluated by the cryogenic magnet. The transition temperature of the MgB2 specimen synthesized using crystalline magnesium and full amorphous boron is 42.678 K (ΔTc = 0.877 K).

  1. Photochemical reduction of uranyl ion with triphenylphosphine

    International Nuclear Information System (INIS)

    Brar, A.S.; Sidhu, M.S.; Sandhu, S.S.

    1981-01-01

    Photochemical reduction of uranyl ion with triphenylphosphine has been studied in acetone-water medium in the presence of sulphuric acid at 346nm, 400nm and 434nm wavelengths. The photochemical reduction is of second order and increases with increase in hydrogen ion concentration. Absorption spectra of uranyl ion in acidic medium and uranyl ion with triphenylphosphine do not show any ground state complex formation. The value of quantum yield increases with the wavelength of the radiation increase from 346 to 434nm. Plots of reciprocal of quantum yield for the formation of U(IV) versus reciprocal [triphenylphosphine] are linear. Products characterized by UV and visible, IR and TLC show the formation of U(IV) and triphenylphosphine oxide. On the basis of above observations mechanism of the photochemical reduction has been proposed. (author)

  2. Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

    International Nuclear Information System (INIS)

    Singh, S. C.; Gopal, R.; Kotnala, R. K.

    2015-01-01

    Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 ± 1.2 nm) and titanium dioxide (average size, 4.4 ± 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, related to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects

  3. Phase evolution, mechanical and corrosion behavior of Fe(100-x) Ni(x) alloys synthesized by powder metallurgy

    Science.gov (United States)

    Singh, Neera; Parkash, Om; Kumar, Devendra

    2018-03-01

    In the present investigation, Fe(100-x) Ni(x) alloys (x = 10, 20, 30, 40 and 50 wt%) were synthesized through the evolution of γ-taenite and α-kamacite phases by powder metallurgy route using commercially available Fe and Ni powders. Mechanically mixed powders of Fe and Ni were compacted at room temperature and sintered at three different temperatures 1000, 1200 and 1250 °C for 1 h. Both Ni concentration and sintering temperature have shown a strong impact on the phase formation, tribological and electrochemical behavior. Micro structural study has shown the formation of taenite (γ-Fe,Ni) and kamacite (α-Fe,Ni) phases in the sintered specimens. An increase in Ni fraction resulted in formation of more taenite which reduces hardness and wear resistance of specimens. Increasing the sintering temperature decreased the defect concentration with enhanced taenite formation, aiding to higher densification. Taenite formed completely in Fe50Ni50 after sintering at 1250 °C. Tribological test revealed the maximum wear resistance for Fe70Ni30 specimen due to the presence of both kamacite and taenite in significant proportions. The formation of taenite as well as the decrease in defect concentration improves the corrosion resistance of the specimens significantly in 1M HCl solution. A maximum corrosion protection efficiency of around ∼87% was achieved in acidic medium for Fe50Ni50, sintered at 1250 °C.

  4. Thermal decomposition of uranyl sulphate hydrate

    International Nuclear Information System (INIS)

    Sato, T.; Ozawa, F.; Ikoma, S.

    1980-01-01

    The thermal decomposition of uranyl sulphate hydrate (UO 2 SO 4 .3H 2 O) has been investigated by thermogravimetry, differential thermal analysis, X-ray diffraction and infrared spectrophotometry. As a result, it is concluded that uranyl sulphate hydrate decomposes thermally: UO 2 SO 4 .3H 2 O → UO 2 SO 4 .xH 2 O(2.5 = 2 SO 4 . 2H 2 O → UO 2 SO 4 .H 2 O → UO 2 SO 4 → α-UO 2 SO 4 → β-UO 2 SO 4 → U 3 O 8 . (author)

  5. Splitting of the luminescent excited state of the uranyl ion

    International Nuclear Information System (INIS)

    Flint, C.D.; Sharma, P.; Tanner, P.A.

    1982-01-01

    The luminescence spectra of some uranyl compounds has been studied. It has been proposed that the splitting of the luminescent excited state of the uranyl ion is due to a descent in symmetry experienced by the uranyl ion when it is placed in a crystal field. In recent years there has been developed a highly successful model of the electronic structure of the uranyl ion. In this paper the authors use this model to interpret the luminescence spectra of a variety of uranyl compounds

  6. Luminescence enhancement of uranyl ion by benzoic acid in acetonitrile

    International Nuclear Information System (INIS)

    Satendra Kumar; Maji, S.; Joseph, M.; Sankaran, K.

    2014-01-01

    Uranyl ion is known for its characteristic green luminescence and therefore luminescence spectroscopy is a suitable technique for characterizing different uranyl species. In aqueous medium, luminescence of uranyl ion is generally weak due to its quenching by water molecules and therefore in order to enhance the luminescence of uranyl ion in aqueous medium, luminescence enhancing reagents such as H 3 PO 4 , H 2 SO 4 , HCIO 4 have been widely used. The other method to enhance the uranyl luminescence is by ligand sensitized luminescence, a method well established for lanthanides. In this work, luminescence of uranyl ion is found to be enhanced by benzoic acid in acetonitrile medium. In aqueous medium benzoic acid does not enhance the uranyl luminescence although it forms 1:1 and 1:2 complexes with uranyl ion. Luminescence spectra of uranyl benzoate revealed that enhancement is due to sensitization of uranyl luminescence by benzoate ions. UV-Vis spectroscopy has been utilized to characterize the specie formed in the in acetonitrile medium. UV-Vis spectroscopy along with luminescence spectra revealed that the specie to be tribenzoate complex of uranyl (UO 2 (C 6 H 5 COO) 3 ) - having D 3 h symmetry. (author)

  7. Study of the extraction mechanisms by TBP saturated by uranyl nitrate; Etude des mecanismes d'extraction du TBP sature par le nitrate d'uranyle

    Energy Technology Data Exchange (ETDEWEB)

    Meze, F

    2004-02-15

    This work deals with a particular phenomenon likely to occur in the nuclear waste reprocessing process PUREX. It was shown earlier by Russian works that the extractant molecule, tributyl phosphate (TBP), saturated by uranyl nitrate keeps its extraction capacities for nitric acid and tetravalent actinides. This study is composed of three parts. Firstly, some liquid-liquid extraction experiments were conducted to verify the ability of TBP saturated by uranyl nitrate to conserve its extraction capacities for nitric acid. Then, during these experiments, the UV and infrared spectra of both phases were recorded to obtain the organic phase speciation. At last, the informations gathered during the experimental part were used to build a general species distribution model of the H{sub 2}O/HNO{sub 3}/UO{sub 2}(NO{sub 3}){sub 2}/TBP system. (author)

  8. Determination of uranyl nitrate diffusion coefficients in organic and aqueous media using the porous diaphragm method

    International Nuclear Information System (INIS)

    Chierice, G.O.

    1974-01-01

    The diffusion coefficient is one of the parameters necessary for the obtention of the extraction exponential coefficients, that are contained within the H.T.U. (height of transfer unity) calculation expression, when operating with continuous organic phase. The organic phase used was tri-n-butyl-phosphate (TBP) and varsol in the 35% and 65% proportions respectively. After each experiment, the uranium content present in each compartment was spectrophotometrically determined and the quantities contained in the aqueous phases were determined by means of volumetric titration. It was found out that the uranyl ion diffusion coefficient is two and one half times less in organic phase, this just being attributed to the greater interactions of the uranyl ions in organic than in aqueous medium

  9. Photochemical reduction of uranyl ion with amides

    International Nuclear Information System (INIS)

    Brar, A.S.; Chander, R.; Sandhu, S.S.

    1981-01-01

    The photochemical reduction of uranyl ion by formamide, acetamide, propionamide, butyramide, iso butyramids, n-methylformamide, N, N-dimethylformamide and N, N-diethylformamide in aqueous medium using radiation >= 380 nm from a medium pressure mercury vapour lamp has been investigated. The reduction with the said amides has been found to obey pseudo first order kinetics. The magnitude of the rate of reduction for the simple amides has been found to follow the following order formamide > isobutyramide approx. butyramide > propionamide > acetamide while the rate order for N-alkylformamides compared with that of the formamide has been found to be formamide > N-methylformamide > N,N-diethylformamide approx. N,N-dimethylformamide. The pseudo first order rate constants and quenching constants have been found from the kinetic data. It has been found that physical and chemical quenching compete with each other. Plots of reciprocal of quantum yields versus reciprocal [amide] have been found to be linear with intercepts on the ordinate axis. Absorption spectra of uranyl ion in doubly distilled water, in the presence of acid and in the presence of acid and amide reveal that there is no ground state interaction between uranyl ion and the amide. A mechanism of photoreduction of uranyl ion with amides has been proposed. (author)

  10. Treatment of uranyl nitrate and flouride solutions

    International Nuclear Information System (INIS)

    Rodrigo Otero, A.; Rodrigo Vilaseca, F.; Morales Calvo, G.

    1977-01-01

    A theoretical study on the fluoride complexes contained in uranyl and aluminium solutions has been carried out. Likewise concentration limits and Duhring diagrams for those solutions have been experimentally established. As a result, the optimum operation conditions for concentration by evaporation in the treatment plant, have been deduced. (Author) 12 refs

  11. The system uranyl nitrate-dietyl ether-water. Extraction by water in spray and packed columns from uranyl nitrate-either solutions

    International Nuclear Information System (INIS)

    Perez Luina, A.; Gutierrez Jodra, L.

    1960-01-01

    This paper is a continuation of the one published in Chemical Engineering Progress. Symposium Series, 50, n. 12, 127 (1954). New runs for spray columns, are given and other concentrations in uranyl nitrate for the packed columns. New correlations for the overall H.T.U. are also given. The individual H.T.U. have been grapycally calculated and show that the film resistances have similar values, being independent of the concentration of the ether phase. (Author) 24 refs

  12. Process control for a continuous uranyl nitrate evaporator

    International Nuclear Information System (INIS)

    Peterson, S.F.; MacIntyre, L.P.

    1984-07-01

    A continuous uranyl nitrate evaporator at the Savannah River Plant (SRP) in Aiken, South Carolina ws the subject of this work. A rigorous mathematical model of the evaporator was developed. A difference equation form of the model was then constructed and used for control studies. Relative gain analysis was done on the system in order to identify any promising multivariable control schemes. Several alternate control schemes were modeled, tuned, and compared against the scheme presently in use at SRP. As the pneumatic specific gravity instrumentation at SRP is very noisy, the noise was simulated and used in the second phase of the control study. In this phase, alternate tuning methods and filters were invesigated and compared. The control studies showed that the control algorithm now in use at SRP is the simplest and best available. 10 references, 53 figures, 22 tables

  13. Synthesis and investigation of uranyl molybdate UO2MoO4

    International Nuclear Information System (INIS)

    Nagai, Takayuki; Sato, Nobuaki; Kitawaki, Shin-ichi; Uehara, Akihiro; Fujii, Toshiyuki; Yamana, Hajimu; Myochin, Munetaka

    2013-01-01

    In order to examine easily synthetic conditions of uranyl molybdate, UO 2 MoO 4 , used for the reprocessing process study of spent nuclear oxide fuels in alkaline molybdate melts, the uranium molybdate compounds were produced from U 3 O 8 powder and anhydrous MoO 3 reagent. The results of having investigated them in solid state by using X-ray diffractometry and Raman spectrometry, it was confirmed that UO 2 MoO 4 could be synthesized by heating mixed powder of U 3 O 8 and MoO 3 with stoichiometric mole ratio at 770 °C for 4 h under air atmosphere. Moreover, adding this UO 2 MoO 4 into Li 2 MoO 4 -Na 2 MoO 4 eutectic melt, most of the dissolved uranium species in the melt were observed as hexa–valent uranyl ions by absorption spectrophotometry

  14. Interfacial tension in systems involving TBP in dodecane, nitric acid, uranyl nitrate and water

    International Nuclear Information System (INIS)

    Kolarik, Z.; Pipkin, N.

    1982-08-01

    The interfacial tension was measured at 25 0 C in the systems TBP - n-dodecane/nitric acid - water and TBP - n-dodecane/nitric acid - uranyl nitrate - water. Empirical equations describing the interfacial tension as a function of the concentration of TBP in the starting organic phase and of uranium-(VI) and nitric acid in the equilibrium aqueous phase were suggested. In the absence of uranium (VI), the interfacial tension can also be correlated with the concentration of water in the equilibrium organic phase. Free TBP, hydrated or nonhydrated, and hydrated TBP solvates of nitric acid are interfacially active. Anhydrous TBP solvates of nitric acid and the TBP solvate of uranyl nitrate, which neither is hydrated, do not exhibit any visible interfacial activity. (orig.) [de

  15. Comparison of morphology and phase composition of hydroxyapatite nanoparticles sonochemically synthesized with dual- or single-frequency ultrasonic reactor

    Science.gov (United States)

    Deng, Shi-ting; Yu, Hong; Liu, Di; Bi, Yong-guang

    2017-10-01

    To investigate how a dual- or single-frequency ultrasonic reactor changes the morphology and phase composition of hydroxyapatite nanoparticles (nHAPs), we designed and constructed the preparation of nHAPs using dual- or single-frequency ultrasonic devices, i.e., the single frequency ultrasonic generator with ultrasonic horn (25 kHz), the ultrasonic bath (40 kHz) and the dual-frequency sonochemical systems combined with the ultrasonic horn and the ultrasonic bath simultaneously (25 + 40 kHz). The results showed that the sonicated samples displayed a more uniform shape with less agglomeration than non-sonicated sample. The rod-shaped particles with 1.66 stoichiometry and without a second phase were synthesized successfully in the ultrasonic bath or horn systems. The nHAPs obtained from the dual-frequency ultrasonic systems exhibited a regular rod-shaped structure with better dispersion and more uniform shapes than those of obtained in either ultrasonic bath or horn systems. Additionally, the size of rod-shaped particles obtained in the dual-frequency ultrasound with a mean width of 35 nm and a mean length of 64 nm was smaller than other samples. A possible mechanism is that the dual-frequency ultrasound significantly enhances the cavitation yield over single frequency ultrasound and thus improves the dispersion of particles and reduces the size of the crystals. In addition, irregular holes can be observed in the nanoparticles obtained in the dual-frequency ultrasound. Therefore, the dual-frequency ultrasonic systems are expected to become a convenient, efficient and environmentally friendly synthetic technology to obtain well-defined nHAPs for specific biomedical applications.

  16. Influence of calcination temperature on sol-gel synthesized single-phase bismuth titanate for high dielectric capacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Thiruramanathan, Pandirengan; Marikani, Arumugam [Mepco Schlenk Engineering College, Tamil Nadu (India). Dept. of Physics; Madhavan, Durairaj [Mepco Schlenk Engineering College, Tamil Nadu (India). Dept. of Chemistry; Bharadwaj, Suresh; Awasthi, Anand Mohan [UGC-DAE Consortium for Scientific Research, Indore (India). Thermodynamics Lab.

    2016-05-15

    An inexpensive sol-gel combustion method using citric acid as fuel has been used to synthesize bismuth titanate, Bi{sub 4}Ti{sub 3}O{sub 12} nanopowders. Thermogravimetric analysis proved that a calcination temperature of 900 C is sufficient for the preparation of single-phase bismuth titanate. X-ray diffraction and Fourier transform infrared spectroscopy are used to examine the influence of calcination temperature on the structural growth of the Bi{sub 4}Ti{sub 3}O{sub 12} nanopowder. The average crystallite size estimated by using the Scherrer method and the Williamson-Hall method was found to increase with calcination temperature. Photoluminescence behavior as a function of calcination temperature was observed at two different excitation wavelengths of 300 nm and 420 nm. The morphology of the particles analyzed using images obtained from field emission scanning electron microscopy displayed irregular, random sized, and spherical-shaped structures. The stoichiometry and purity of the nanopowder are confirmed by energy-dispersive spectroscopy. The broadband dielectric results established the highest dielectric constant (ε{sub r} = 450) for a frequency of 100 Hz achieved with a potential capacitance of 138 pF m{sup -2}. This establishes Bi{sub 4}Ti{sub 3}O{sub 12} as a promising dielectric material for achieving high energy density capacitors for the next-generation passive devices.

  17. Synthesis, structural characterization, and dehydration analysis of uranyl zinc mellitate, (UO{sub 2})Zn(H{sub 2}O){sub 4}(H{sub 2}mel).2H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Olchowka, Jakub; Volkringer, Christophe; Henry, Natacha; Loiseau, Thierry [Unite de Catalyse et Chimie du Solide (UCCS) - UMR CNRS 8181, Universite de Lille Nord de France, USTL-ENSCL, Villeneuve d' Ascq (France)

    2013-04-15

    A new heterometallic uranyl zinc carboxylate, (UO{sub 2})Zn(H{sub 2}O){sub 4}(H{sub 2}mel).2H{sub 2}O, has been hydrothermally prepared (150 C, 24 h) by using 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid) as organic linker in order to form a three-dimensional network. Four of the six carboxylate groups of the mellitate ligand interact with mononuclear uranyl or zinc cations, which are eightfold (hexagonal bipyramid, UO{sub 8}) or sixfold [octahedron, ZnO{sub 2}(H{sub 2}O){sub 4}] coordinated, respectively. The remaining free carboxylate arms of the mellitate species preferentially interact through hydrogen bonds with water molecules trapped within the framework. Thermogravimetric and X-ray thermodiffraction (up to 800 C) analyses and in situ infrared spectroscopy (up to 210 C) indicated that both free and bound water species are evacuated from the structure in one step between 80 and 170 C, followed by its transformation into an unknown, anhydrous, poorly crystalline phase [UO{sub 2}Zn(mel)] up to 320 C. After the formation of an amorphous phase, the re-crystallization of oxides α-ZnU{sub 3}O{sub 10} and ZnO was observed from 460 C. The fluorescence spectrum of the as-synthesized uranyl zinc mellitate shows the six bands that are typical for vibronic couplings of the [O=U=O]{sup 2+} moiety. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Micro-SHINE Uranyl Sulfate Irradiations at the Linac

    Energy Technology Data Exchange (ETDEWEB)

    Youker, Amanda J. [Argonne National Lab. (ANL), Argonne, IL (United States); Kalensky, Michael [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States); Schneider, John [Argonne National Lab. (ANL), Argonne, IL (United States); Byrnes, James [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-08-01

    Peroxide formation due to water radiolysis in a uranyl sulfate solution is a concern for the SHINE Medical Technologies process in which Mo-99 is generated from the fission of dissolved low enriched uranium. To investigate the effects of power density and fission on peroxide formation and uranyl-peroxide precipitation, uranyl sulfate solutions were irradiated using a 50-MeV electron linac as part of the micro-SHINE experimental setup. Results are given for uranyl sulfate solutions with both high and low enriched uranium irradiated at different linac powers.

  19. Cyanex based uranyl sensitive polymeric membrane electrodes.

    Science.gov (United States)

    Badr, Ibrahim H A; Zidan, W I; Akl, Z F

    2014-01-01

    Novel uranyl selective polymeric membrane electrodes were prepared using three different low-cost and commercially available Cyanex extractants namely, bis(2,4,4-trimethylpentyl) phosphinic acid [L1], bis(2,4,4-trimethylpentyl) monothiophosphinic acid [L2] and bis(2,4,4-trimethylpentyl) dithiophosphinic acid [L3]. Optimization and performance characteristics of the developed Cyanex based polymer membrane electrodes were determined. The influence of membrane composition (e.g., amount and type of ionic sites, as well as type of plasticizer) on potentiometric responses of the prepared membrane electrodes was studied. Optimized Cyanex-based membrane electrodes exhibited Nernstian responses for UO₂(2+) ion over wide concentration ranges with fast response times. The optimized membrane electrodes based on L1, L2 and L3 exhibited Nernstian responses towards uranyl ion with slopes of 29.4, 28.0 and 29.3 mV decade(-1), respectively. The optimized membrane electrodes based on L1-L3 showed detection limits of 8.3 × 10(-5), 3.0 × 10(-5) and 3.3 × 10(-6) mol L(-1), respectively. The selectivity studies showed that the optimized membrane electrodes exhibited high selectivity towards UO₂(2+) ion over large number of other cations. Membrane electrodes based on L3 exhibited superior potentiometric response characteristics compared to those based on L1 and L2 (e.g., widest linear range and lowest detection limit). The analytical utility of uranyl membrane electrodes formulated with Cyanex extractant L3 was demonstrated by the analysis of uranyl ion in different real samples for nuclear safeguards verification purposes. The results obtained using direct potentiometry and flow-injection methods were compared with those measured using the standard UV-visible and inductively coupled plasma spectroscopic methods. © 2013 Published by Elsevier B.V.

  20. Studies on conductance of uranyl soaps

    International Nuclear Information System (INIS)

    Mehrotra, K.N.; Sharma, M.; Gahlaut, A.S.

    1987-01-01

    Specific conductance of uranyl soaps in dimethylformamide indicates two critical micelle concentrations CMC(I) and CMC(II). The value of CMC(II) decreases with the increase in chain length of the soap, whereas CMC(I) does not vary at all. The results show that the soaps behave as simple electrolyte. The major conductance at infinite dilution (μsub(o)) and dissociation constant (K) of these soaps have been evaluated. (author). 12 refs

  1. Thermal decomposition kinetics of ammonium uranyl carbonate

    International Nuclear Information System (INIS)

    Kim, E.H.; Park, J.J.; Park, J.H.; Chang, I.S.; Choi, C.S.; Kim, S.D.

    1994-01-01

    The thermal decomposition kinetics of AUC [ammonium uranyl carbonate; (NH 4 ) 4 UO 2 (CO 3 ) 3 [ in an isothermal thermogravimetric (TG) reactor under N 2 atmosphere has been determined. The kinetic data can be represented by the two-dimensional nucleation and growth model. The reaction rate increases and activation energy decreases with increasing particle size and precipitation time which appears in the particle size larger than 30 μm in the mechano-chemical phenomena. (orig.)

  2. Process for obtaining ammonium uranyl tri carbonate

    International Nuclear Information System (INIS)

    Santos, L.R. dos; Riella, H.G.

    1992-01-01

    The procedure adopted for obtaining Ammonium Uranyl Carbonate (AUC) from uranium hexafluoride (U F 6 ) in a aqueous solutions of ammonium hydrogen carbonate is described in this work. The precipitation is made in temperature and pH controlled. This process consists of three steps: evaporation of U F 6 , AUC precipitation and filtration of the AUC slurry. An attempt is made of correlate the parameters involved in the precipitation process of AUC with its and U O 2 characteristics. (author)

  3. A wide bandwidth fractional-N synthesizer for LTE with phase noise cancellation using a hybrid-ΔΣ-DAC and charge re-timing

    NARCIS (Netherlands)

    Ye, D.; Lu, Ping; Andreani, Pietro; van der Zee, Ronan A.R.

    2013-01-01

    This paper presents a 1MHz bandwidth, ΔΣ fractional-N PLL as the frequency synthesizer for LTE. A noise cancellation path composed of a novel hybrid ΔΣ DAC with 9 output bits is incorporated into the PLL in order to cancel the out-of-band phase noise caused by the quantization error. Further, a

  4. Metal organic vapor phase epitaxy growth of (Al)GaN heterostructures on SiC/Si(111) templates synthesized by topochemical method of atoms substitution

    DEFF Research Database (Denmark)

    Rozhavskaya, Mariia M.; Kukushkin, Sergey A.; Osipov, Andrey V.

    2017-01-01

    We report a novel approach for metal organic vapor phase epitaxy of (Al)GaN heterostructures on Si substrates. An approximately 90–100 nm thick SiC buffer layer is synthesized using the reaction between Si substrate and CO gas. Highresolution transmission electron microscopy reveals sharp...

  5. Effect of temperature on internal structure of uranyl gels

    International Nuclear Information System (INIS)

    Landspersky, H.; Urbanek, V.

    1983-01-01

    Tempering freshly prepared uranyl gel serves the homogenization of the volume of the individual spheres and the whole volume of the processed material. Tempering is carried out at a temperature of 90 degC in a special countercurrent through-flow column. The tempered gel particles were analyzed for specific surface and porosity using different methods, subjected to phase analysis, and the crystallite mean size was determined. It was found that the quality of the final gel depends on the residence time in the tempering column. Gel recrystallization probably takes place during tempering leading to stress and cracks which in the final stage lead to the disintegration of the xerogel. Maximum permissible gel residence time in the tempering column is 15 mins. (M.D.)

  6. Magnetic biosorbent for removal of uranyl ions

    International Nuclear Information System (INIS)

    Yamamura, Amanda P.G.; Yamaura, Mitiko; Costa, Caroline H.

    2009-01-01

    In this work magnetic biosorbent, which consisted of sugarcane bagasse as polymeric matrix with magnetite nanoparticles, was prepared. This magnetic composite has the purpose to remove uranyl ions from aqueous effluents. The magnetite was synthetized by simultaneous precipitation by addition a solution of NaOH to the aqueous solution containing Fe2+ and Fe3+. This magnetic bagasse biosorbent have presented superparamagnetic properties, that is, it have showed a high magnetization of saturation without hysteresis. The magnetic biosorbent was utilized to remove uranyl ions from water. Radioactive uranium waste is generated in hospitals, universities and it is used as fuel for nuclear power plants. Variables of adsorption process of uranyl ions by magnetic biosorbent in nitric solutions were investigated, such as, time required for the uranium-magnetic bagasse biosorbent equilibrium in the interval from 20 to 90 min, pH in the intervals from 2 to 5 and 10, stirring speed from 240 to 500 r.p.m. and biosorbent dose from 2 to 25 g.L-1 were investigated. Equilibrium isotherm was verified according to the Langmuir and Freundlich adsorption isotherm models. The highest adsorption capacity reached 17 mg.g-1. The Gibbs free energy indicated to be spontaneous adsorption. This work updates the paper was presented on the 2007 INAC.

  7. Friction and wear characteristics of Al-Cu/C composites synthesized using partial liquid phase casting process

    International Nuclear Information System (INIS)

    Ng, W.B.; Gupta, M.; Lim, S.C.

    1997-01-01

    During the sliding of aluminium alloys dispersed with graphite particulates, a layer of graphite is usually present at the sliding interface. This tribo-layer significantly reduces the amount of direct metal-to-metal contact, giving rise to low friction and a low rate of wear, making these composites useful candidate materials for anti-friction applications. Such self-lubricating composites are commonly fabricated via the squeeze casting, slurry casting or powder metallurgy route. These processes are expensive while the less-expensive conventional casting route is limited by the agglomeration of graphite particles in the composites, giving rise to poor mechanical properties. In this work, graphite particulate-reinforced Al-4.5 wt.% Cu composites with two effective graphite contents (Al-4.5 Cu/4.2 wt.% C and Al-4.5 Cu/6.8 wt.% C) were synthesized through an innovative partial liquid phase casting (rheocasting) technique, which is a modification of the conventional casting process. Unlubricated (without the use of conventional liquid lubrication) friction and wear performance of these composites as well as the un-reinforced aluminium alloy was determined using a pin-on-disk tester. The results revealed that the graphite-reinforced composites have a higher wear rate than the un-reinforced matrix alloy while their frictional characteristics are very similar within the range of testing conditions. Combining these with the information gathered from worn-surface examinations and wear-debris analysis, it is suggested that there exists a certain threshold for the amount and size of graphite particulates in these composites to enable them to have improved tribological properties. (Copyright (c) 1997 Elsevier Science B.V., Amsterdam. All rights reserved.)

  8. Solid-phase extraction of the alcohol abuse biomarker phosphatidylethanol using newly synthesized polymeric sorbent materials containing quaternary heterocyclic groups.

    Science.gov (United States)

    Duarte, Mariana; Jagadeesan, Kishore Kumar; Billing, Johan; Yilmaz, Ecevit; Laurell, Thomas; Ekström, Simon

    2017-10-13

    Phosphatidylethanol (PEth) is an interesting biomarker finding increased use for detecting long term alcohol abuse with high specificity and sensitivity. Prior to detection, sample preparation is an unavoidable step in the work-flow of PEth analysis and new protocols may facilitate it. Solid-phase extraction (SPE) is a versatile sample preparation method widely spread in biomedical laboratories due to its simplicity of use and the possibility of automation. In this work, SPE was used for the first time to directly extract PEth from spiked human plasma and spiked human blood. A library of polymeric SPE materials with different surface functionalities was screened for PEth extraction in order to identify the surface characteristics that control PEth retention and recovery. The plasma samples were diluted 1:10 (v/v) in water and spiked at different concentrations ranging from 0.3 to 5μM. The library of SPE materials was then evaluated using the proposed SPE method and detection was done by LC-MS/MS. One SPE material efficiently retained and recovered PEth from spiked human plasma. With this insight, four new SPE materials were formulated and synthesized based on the surface characteristics of the best SPE material found in the first screening. These new materials were tested with spiked human blood, to better mimic a real clinical sample. All the newly synthetized materials outperformed the pre-existing commercially available materials. Recovery values for the new SPE materials were found between 29.5% and 48.6% for the extraction of PEth in spiked blood. A material based on quaternized 1-vinylimidazole with a poly(trimethylolpropane trimethacrylate) backbone was found suitable for PEth extraction in spiked blood showing the highest analyte recovery in this experiment, 48.6%±6.4%. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Contribution to the study of the evaporation of aqueous uranyl nitrate solutions; Contribution a l'etude de l'evaporation des solutions aqueuses de nitrate d'uranyle

    Energy Technology Data Exchange (ETDEWEB)

    Billy, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-05-15

    This work was carried out with a view to define the conditions under which is affected the concentration of aqueous uranyl nitrate solutions one of the steps in uranium extraction metallurgy. The first port is devoted to the experimental determination of the physical characteristics of aqueous uranyl nitrate solutions, from dilute to concentrated solutions. The second part of this work is devoted to the isothermal evaporation of solution a west ted-wall column; this chemical engineering study has been more particularly devoted to the definition of the influence of the dynamics of the liquid phase on the exchange of matter between the two phases in contact. (author) [French] La concentration par evaporation des solutions aqueuses de nitrate d'uranyle constitue une etape de la metallurgie de l'uranium dont ce travail a voulu preciser la connaissance. Dans ce but, une premiere partie a ete consacree a la determination experimentale de caracteristiques physiques des solutions aqueuses de nitrate d'uranyle, des solutions diluees aux solutions saturees. Dans une deuxieme partie, ce travail a porte sur l'evaporation isotherme des solutions dans une colonne a paroi mouillee; cette etude de genie chimique a ete plus particulierement orientee de facon a preciser l'influence de la dynamique de la phase liquide sur l'echange de matiere entre les deux phases en contact. (auteur)

  10. Uranyl sulfate irradiations at the Van de Graaff: A means to combat uranyl peroxide precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Youker, Amanda J. [Argonne National Lab. (ANL), Argonne, IL (United States); Kalensky, Michael [Argonne National Lab. (ANL), Argonne, IL (United States); Quigley, Kevin J. [Argonne National Lab. (ANL), Argonne, IL (United States); Brossard, Thomas [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, Sergey D. [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-05-01

    As part of an effort to support SHINE Medical Technologies in developing a process to produce Mo-99 by neutron-induced fission, a series of irradiation experiments was performed with a 3 MeV Van de Graaff accelerator to generate high radiation doses in 0.5–2 mL uranyl sulfate solutions. The purpose was to determine what conditions result in uranyl peroxide precipitation and what can be done to prevent its formation. The effects of temperature, dose rate, uranium concentration, and the addition of known catalysts for the destruction of peroxide were determined.

  11. Determination of uranyl ion by potentiometric titration using an uranyl-selective electrode

    International Nuclear Information System (INIS)

    Nassory, N.S.

    1990-01-01

    A potentiometric titration of uranyl ion is described using an uranyl selective electrode based on a membrane containing a complex of UO 2 -bis[di-4-(1,1,3,3-tetramethylbutyl)phenyl phosphate] as an ion-exchanger and tritolyl phosphate as a solvent mediator. The titrations were carried out with various titrants: Sodium hydroxide, potassium fluoride and sodium salts of acetate, oxalate and citrate. The equivalence points were determined by Gran's method. Good results were obtained by using sodium oxalate as a titrant for the determination of uranium in several samples of ammonium diuranate. The results were quite comparable with those obtained by X-ray fluorescence spectrometry. (orig.)

  12. Influence of pH on structural morphology and magnetic properties of ordered phase cobalt doped lithium ferrites nanoparticles synthesized by sol-gel method

    International Nuclear Information System (INIS)

    Srivastava, Manish; Ojha, Animesh K.; Chaubey, S.; Sharma, Prashant K.; Pandey, Avinash C.

    2010-01-01

    Cobalt doped lithium ferrite nanoparticles were synthesized at different pH by sol-gel method. The effect of pH on the physical properties of cobalt doped lithium ferrite nanoparticles has been investigated. The nanoparticles synthesized at different pH were characterized through X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy (RS), Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and vibrating sample magnetometer (VSM). The XRD patterns were analyzed to determine the crystal phase of cobalt doped lithium ferrites nanoparticles synthesized at different pH. The XRD results show the formation of impurity free cobalt doped lithium ferrites having ordered phase spinel structure. A similar kind of conclusion was also drawn through the analysis of Raman spectra of the nanoparticles synthesized at different pH. SEM micrographs show that the structural morphology of the nanoparticles is highly sensitive to the pH during the synthesis process. The magnetic properties such as; saturation magnetization (Ms), remnant magnetization (Mr) and coercivety (Hc) have been also investigated and found to be different for the nanoparticles synthesized at different pH, which may be attributed to the different size and surface morphology of the nanoparticles.

  13. Synthesis and X-ray diffraction study of new uranyl malonate and oxalate complexes with carbamide

    International Nuclear Information System (INIS)

    Medvedkov, Ya. A.; Serezhkina, L. B.; Grigor’ev, M. S.; Serezhkin, V. N.

    2016-01-01

    Two new malonate-containing uranyl complexes with carbamide of the formulas [UO 2 (C 3 H 2 O 4 )(Urea) 2 ] (I) and [UO 2 (C 3 H 2 O 4 )(Urea) 3 ] (II), where Urea is carbamide, and one uranyl oxalate complex of the formula [UO 2 (C 2 O 4 )(Urea) 3 ] (III) were synthesized, and their crystals were studied by X-ray diffraction. The main structural units in crystals I are the electroneutral chains [UO 2 (C 3 H 2 O 4 )(Urea) 2 ] ∞ belonging to the crystal-chemical group AT 11 M 2 1 (A = UO 2 2+ , T 11 = C 3 H 2 O 4 2- , M 1 = Urea) of uranyl complexes. Crystals II and III are composed of the molecular complexes [UO 2 (L)(Urea) 3 ], where L = C 3 H 2 O 4 2- or C 2 O 4 2- , belonging to the crystal-chemical group AB 01 M 3 1 (A = UO 2 2+ , B 01 = C 3 H 2 O 4 2- or C 2 O 4 2- , M 1 = Urea). The characteristic features of the packing of the uranium-containing complexes are discussed in terms of molecular Voronoi–Dirichlet polyhedra. The effect of the Urea: U ratio on the structure of uranium-containing structural units is considered.

  14. An unprecedented two-fold nested super-polyrotaxane: sulfate-directed hierarchical polythreading assembly of uranyl polyrotaxane moieties

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Lei; Wu, Qun-yan; Yuan, Li-yong; Wang, Lin; An, Shu-wen; Xie, Zhen-ni; Hu, Kong-qiu; Shi, Wei-qun [Laboratory of Nuclear Energy Chemistry and Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing (China); Chai, Zhi-fang [Laboratory of Nuclear Energy Chemistry and Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing (China); School of Radiological and Interdisciplinary Sciences and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou (China); Burns, Peter C. [Department of Chemistry and Biochemistry, University of Notre Dame, IN (United States)

    2016-08-01

    The hierarchical assembly of well-organized submoieties could lead to more complicated superstructures with intriguing properties. We describe herein an unprecedented polyrotaxane polythreading framework containing a two-fold nested super-polyrotaxane substructure, which was synthesized through a uranyl-directed hierarchical polythreading assembly of one-dimensional polyrotaxane chains and two-dimensional polyrotaxane networks. This special assembly mode actually affords a new way of supramolecular chemistry instead of covalently linked bulky stoppers to construct stable interlocked rotaxane moieties. An investigation of the synthesis condition shows that sulfate can assume a vital role in mediating the formation of different uranyl species, especially the unique trinuclear uranyl moiety [(UO{sub 2}){sub 3}O(OH){sub 2}]{sup 2+}, involving a notable bent [O=U=O] bond with a bond angle of 172.0(9) . Detailed analysis of the coordination features, the thermal stability as well as a fluorescence, and electrochemical characterization demonstrate that the uniqueness of this super-polyrotaxane structure is mainly closely related to the trinuclear uranyl moiety, which is confirmed by quantum chemical calculations. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Can uranyl complexes encapsulate to carbon nanotubes? A ...

    Indian Academy of Sciences (India)

    K SRINIVASU

    We find that uranyl-aqua complex ([UO2(H2O)5]2+) binds stronger as compared to uranyl-hydroxo-complex .... until the maximum Hellmann–Feynman force on each atom ..... porters and near-infrared agents for selective cancer cell.

  16. Uranyl ion recovery from waste waters by microbiological collectors

    International Nuclear Information System (INIS)

    Cecal, Alexandru; Palamaru, Iliana; Navrotescu, Tinca

    1995-01-01

    This study deals with the bioaccumulation of uranyl ions from radioactive effluents by Scenedesmus quadricauda alga. From the experimental data one can observe a greater retaining capacity of uranyl ions after four days of contact time. Filtered uranium and alga content was determined by the arsenazo III spectrophotometric method. The colored compound was determined by using wavelength λ=665 nm. (authors)

  17. New insights into the acid mediated disproportionation of pentavalent uranyl

    Energy Technology Data Exchange (ETDEWEB)

    Mougel, Victor; Biswas, Biplab; Pecaut, Jacques; Mazzanti, Marinella [Laboratoire de Reconnaissance Ionique et Chimie de Coordination, SCIB, UMR-E 3 CEA-UJF FRE 3200 CNRS, INAC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 09 (France)

    2010-07-01

    The reaction of benzoic acid with the uranyl(V) complex [(UO{sub 2}Py{sub 5})(KI{sub 2}Py{sub 2})] in pyridine leads to immediate disproportionation with formation of a hexa-nuclear U(IV) benzoate cluster, a bis-benzoate complex of uranyl(VI) and water. (authors)

  18. Densities concentrations of aqueous of uranyl nitrate solutions

    International Nuclear Information System (INIS)

    Rodrigo Otero, A.; Rodriguez Hernandez, B.; Fernandez Rodriguez, L.

    1966-01-01

    The ratio density-concentration of aqueous uranyl nitrate solutions expressed as U 3 O 8 grams/liter, U grams/liter and hexahydrate uranyl nitrate weight percent at different temperatures, are established. Experimental values are graphically correlated and compared whit some published data. (Author) 2 refs

  19. Uranyl(VI)-acetylacetonate coordination compounds with various N-heterocyclic ligands

    International Nuclear Information System (INIS)

    Kawasaki, Takeshi; Nishimura, Tatsuru; Kitazawa, Takafumi

    2010-01-01

    Seven uranyl(VI) complexes, [UO 2 (acac) 2 (L)] [L=4-methylpyridine (1), 4-ethylpyridine (2), 2,4-dimethylpyridine (3), (-)-nicotine (4), and imidazole (5)], [{UO 2 (acac) 2 } 2 -(4,4'-bipyridine)] (6), and [(2,2'-bipyridine) 2 H][UO 2 (acac)(NO 3 ) 2 ] (7) have been synthesized and characterized crystallographically. The coordination geometry of U has a UNO 6 pentagonal-bipyramidal coordination in 1-6, and a UO 8 hexagonal-bipyramidal coordination in 7. (author)

  20. Beryllium(II), manganese(II) and uranyl(VI)-salicylamide complexes

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, P L; Agarwala, B V; Dey, A K [Allahabad Univ. (India)

    1977-01-01

    The preparation, composition, general properties and i.r. absorption spectra of the solid chelates formed by salicylamide with beryllium(II), manganese(II) and uranyl(VI) are described. The complexes have been synthesized by refluxing a mixture of ethanolic solutions of the reactants (metal:ligand :: 1:2) for several hours in the presence of alkali. Attempts to isolate the complexes by the interaction of ethanolic solutions of the metal salts and the ligand in the absence of alkali did not succeed.

  1. Design and synthesis of new poly-phosphorylated upper-rim modified calix[4]arenes as potential and selective chelating agents of uranyl ion

    International Nuclear Information System (INIS)

    Migianu-Griffoni, E.; Mbemba, C.; Burgada, R.; Lecouvey, M.; Lecercle, D.; Taran, F.

    2009-01-01

    New upper-rim poly-phosphorylated calix[4]arenes were designed for decorporation of uranium in case of nuclear contamination. A ligand system containing four pre-organized 1-hydroxymethylene-1, 1-bisphosphonic acid moieties anchored onto a calix[4]arene platform has been developed. Three calix[4]-arene-bis-phosphonates were efficiently prepared in multi-step syntheses with a variable carbon chain length between the bis-phosphonate and the calix[4]arene. Affinity constants towards uranyl ion were determined and compared with those of bis(HEDP) and tris(HEDP) phosphonates, known as efficient ligands for uranyl. (authors)

  2. Quantification of uranyl in presence of citric acid

    International Nuclear Information System (INIS)

    Garcia G, N.; Barrera D, C.E.; Ordonez R, E.

    2007-01-01

    To determine the influence that has the organic matter of the soil on the uranyl sorption on some solids is necessary to have a detection technique and quantification of uranyl that it is reliable and sufficiently quick in the obtaining of results. For that in this work, it intends to carry out the uranyl quantification in presence of citric acid modifying the Fluorescence induced by UV-Vis radiation technique. Since the uranyl ion is very sensitive to the medium that contains it, (speciation, pH, ionic forces, etc.) it was necessary to develop an analysis technique that stands out the fluorescence of uranyl ion avoiding the out one that produce the organic acids. (Author)

  3. Calorimetric measurement of the enthalpy of extraction of uranyl nitrate by tri-n-amyl phosphate

    International Nuclear Information System (INIS)

    Srinivasan, T.G.; Vasudeva Rao, P.R.; Venugopal, V.; Sood, D.D.

    2002-01-01

    Enthalpy of extraction of uranyl nitrate by tri n-amyl phosphate (TAP) and its solutions in n-dodecane has been directly measured by solution calorimetry for the first time. Measurements have been made at 303±1 K, in both forward as well as the reverse extraction modes. The enthalpies of the accompanying reactions such as the dilution of the uranyl nitrate in the aqueous phase, the hydration of TAP, the mixing of TAP and n-dodecane, the mixing of the metal-solvate (UO 2 (NO 3 ) 2 ·2TAP) and n-dodecane and mixing of the metal-solvate and TAP have also been independently measured and used to derive both the equilibrium state enthalpies and the standard state enthalpies for the extraction. Two distinct standard states have been used for the organic phase, viz., 1) all solutes infinitely diluted in diluent (ΔH*) and 2) all solutes infinitely diluted in the water saturated extractant (ΔH 0 ). The results have been compared with the enthalpies of extraction measured by employing the temperature dependence of the distribution ratio as well as calorimetry reported in the literature for extraction of uranyl nitrate by TAP and TBP. (author)

  4. The effect of poly vinyl alcohol (PVA) surfactant on phase formation and magnetic properties of hydrothermally synthesized CoFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jalalian, M.; Mirkazemi, S.M., E-mail: mirkazemi@iust.ac.ir; Alamolhoda, S.

    2016-12-01

    Nanoparticles of CoFe{sub 2}O{sub 4} were synthesized by hydrothermal process at 190 °C with and without poly vinyl alcohol (PVA) addition using treatment durations of 1.5–6 h. The synthesized powders were characterized with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and vibration sample magnetometer (VSM) techniques. XRD results show presence of CoFe{sub 2}O{sub 4} as the main phase and Co{sub 3}O{sub 4} as the lateral phase in some samples. The results show that in the samples synthesized without PVA addition considerable amount of lateral phase is present after 3 h of hydrothermal treatment while with PVA addition this phase is undetectable in the XRD patterns of the sample synthesized at the same conditions. Microstructural studies represent increasing of particle size with increasing of hydrothermal duration and formation of coarser particles with PVA addition. The highest maximum magnetization (M{sub max}) values in both of the samples that were synthesized with and without PVA addition are about 59 emu/g that were obtained after 4.5 h of hydrothermal treatment. Intrinsic coercive field ({sub i}H{sub c}) value of the sample without PVA addition increases from 210 to 430 Oe. While with PVA addition the {sub i}H{sub c} value changes from 83 Oe to 493 Oe. The mechanism of changes in M{sub max} and {sub i}H{sub c} values has been explained. - Highlights: • Nanoparticles of CoFe{sub 2}O{sub 4} hydrothermally synthesized with and without PVA addition. • PVA addition facilitates formation of single phase cobalt ferrite. • Coarser particles would be obtained with PVA addition. • The highest M{sub max} values in the samples with and without PVA are equal to 59 emu/g. • The highest {sub i}H{sub c} values are equalt to 320 and 493 Oe without and with PVA respectively.

  5. Structural evolution of a uranyl peroxide nano-cage fullerene: U60, at elevated pressures

    Science.gov (United States)

    Turner, K. M.; Lin, Y.; Zhang, F.; McGrail, B.; Burns, P. C.; Mao, W. L.; Ewing, R. C.

    2015-12-01

    U60 is a uranyl peroxide nano-cage that adopts a highly symmetric fullerene topology; it is topologically identical to C60. Several studies on the aqueous-phase of U60 clusters, [UO2(O2)(OH)]6060-, have shown its persistence in complex solutions and over lengthy time scales. Peroxide enhances corrosion of nuclear fuel in a reactor accident-uranyl peroxides often form near contaminated sites. U60 (Fm-3) crystallizes with approximate formula: Li68K12(OH)20[UO2(O2)(OH)]60(H2O)310. Here, we have used the diamond anvil cell (DAC) to examine U60 to understand the stability of this cluster at high pressures. We used a symmetric DAC with 300 μm culet diamonds and two different pressure-transmitting media: a mixture of methanol+ethanol and silicone oil. Using a combination of in situ Raman spectroscopy and synchrotron XRD, and electrospray ionization mass spectroscopy (ESI-MS) ex situ, we have determined the pressure-induced evolution of U60. Crystalline U60 undergoes an irreversible phase transition to a tetragonal structure at 4.1 GPa, and irreversibly amorphizes at 13 GPa. The amorphous phase likely consists of clusters of U60. Above 15 GPa, the U60 cluster is irreversibly destroyed. ESI-MS shows that this phase consists of species that likely have between 10-20 uranium atoms. Raman spectroscopy complements the diffraction measurements. U60 shows two dominant vibrational modes: a symmetric stretch of the uranyl U-O triple bond (810 cm-1), and a symmetric stretch of the U-O2-U peroxide bond (820 cm-1). As pressure is increased, these modes shift to higher wavenumbers, and overlap at 4 GPa. At 15 GPa, their intensity decreases below detection. These experiments reveal several novel behaviors including a new phase of U60. Notably, the amorphization of U60 occurs before the collapse of its cluster topology. This is different from the behavior of solvated C60 at high pressure, which maintains a hcp structure up to 30 GPa, while the clusters disorder. These results suggest

  6. A study on the phase transformation of the nanosized hydroxyapatite synthesized by hydrolysis using in situ high temperature X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Shih, W.-J. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan, 70101, Taiwan (China); Wang, J.-W. [Department of Enviromental and Safety Engineering, Chung Hwa College of Medical Technology, 89 Wen-Hua 1st St., Rende Shiang, Tainan, 71703, Taiwan (China); Wang, M.-C. [Department of Materials Science and Engineering, National United University, 1 Lien-Da, Kung-Ching Li, Miao Li 360, Taiwan (China)]. E-mail: mcwang@nuu.edu.tw; Hon, M.-H. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan, 70101, Taiwan (China); Dayeh University, 112 Shan-Jiau Road, Da-Tsuen, Changhua 515, Taiwan (China)

    2006-09-15

    The biodegradable hydroxyapatite (HA) was synthesized by hydrolysis and characterized using high temperature X-ray diffraction (HT-XRD), differential thermal analysis and thermogravimetry (DTA/TG), and scanning electron microscopy (SEM). The in situ phase transformation of the HA synthesized from CaHPO{sub 4}.2H{sub 2}O (DCPD) and CaCO{sub 3} with a Ca / P = 1.5 in 2.5 M NaOH{sub (aq)} at 75 deg. C for 1 h was investigated by HT-XRD between 25 and 1500 deg. C. The HA was crystallized at 600 deg. C and maintained as the major phase until 1400 deg. C. The HA steadily transformed to the {alpha}-tricalcium phosphate ({alpha}-TCP) which became the major phosphate phase at 1500 deg. C. At 700 deg. C, the minor CaO phase appeared and vanished at 1300 deg. C. The Na{sup +} impurity from the hydrolysis process was responsible for the formation of the NaCaPO{sub 4} phase, which appeared above 800 deg. C and disappeared at 1200 deg. C.

  7. Preparation and properties of uranyl bromate monohydrate

    International Nuclear Information System (INIS)

    Weigel, F.

    1983-01-01

    Uranyl bromate monohydrate UO 2 (BrO 3 ) 2 .H 2 O was obtained as a greenish-yellow solid by the metathesis of a uranyl sulfate solution with a stoichiometric amount of barium bromate solution. On evaporation of the supernatant of the precipitated BaSO 4 a greenish-yellow syrup was obtained which, on dehydration with anhydrous carbon tetrachloride, yielded a free-flowing greenish-yellow powder with stoichiometry UO 2 (BrO 3 ) 2 .H 2 O. Powder diffraction diagrams of UO 2 (BrO 3 ) 2 .H 2 O obtained using the Guinier method yielded an orthorhombic lattice (space group, Pbcn (no. 60)) with a = 8.533 +- 0.003 A, b = 7.639 +- 0.003 A and c = 12.293 +- 0.004 A; the X-ray density was 4.507 g cm -3 . The compound was characterized by chemical analysis, IR spectroscopy and differential thermal analysis. (Auth.)

  8. Structure and spectroscopy of uranyl salicylaldiminate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Tamasi, A.L.; Barnes, C.L.; Walensky, J.R. [Missouri Univ., Columbia, MO (United States). Dept. of Chemistry

    2013-07-01

    The synthesis of uranyl complexes coordinated to tridentate, monoanionic salicylaldiminate (Schiff base) ligands was achieved by the reaction of UO{sub 2}Cl{sub 2}(THF){sub 3}, 1, with one equivalent of the corresponding sodium salicylaldiminate salts affording [(C{sub 9}H{sub 6}N)N=C(H)C{sub 6}H{sub 2}'Bu{sub 2}O]UO{sub 2}Cl(THF), 2, [(NC{sub 5}H{sub 4})N=C(H)C{sub 6}H{sub 2}'Bu{sub 2}O]UO{sub 2}Cl(THF), 3, and [(C{sub 6}H{sub 4}SCH{sub 3})N=C(H)C{sub 6}H{sub 2}'Bu{sub 2}O]UO{sub 2}Cl(THF), 4. These are uncommon examples of uranyl complexes with a monoanionic ancillary ligand to stabilize the coordination sphere and one chloride ligand. Compounds 2-4 have been characterized by {sup 1}H and {sup 13}C NMR spectroscopy as well as IR and UVVis spectroscopy and their structures determined by X-ray crystallography. (orig.)

  9. Contribution to the study of the mechanism of extraction of uranyl chloride by long chain aliphatic amines

    International Nuclear Information System (INIS)

    Rubinstein, G.R.

    1965-06-01

    After having studied and developed the mechanisms which may 'a priori' explain the extraction process (co-ordination, ion association or intermediate mechanism), experience shows that ion association only should be taken into consideration. The structure of the organic complex of uranyl chloride has been defined on the basis of the study of the variation of the distribution coefficient of uranium between the two phases at the equilibrium as a function of successively the activity of Cl - ions in the aqueous phase, the concentration of amine salt in the organic phase and finally of the concentration of uranium in the aqueous phase. The plotting of the results in bi-logarithmic co-ordinates enables us to propose the following formula for the extracted compound: UO 2 Cl 4 -- (NR 3 H + ) 2 . The calculation of the equilibrium constant of formation of the organic compound of uranyl chloride has been possible in the case of diluted solutions of uranium only. (author) [fr

  10. Phase transformation and spectroscopic adjustment of Gd{sub 2}O{sub 3}:Eu{sup 3+} synthesized by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zijun; Wang, Pei; Zhong, Jiuping, E-mail: zhongjp@mail.sysu.edu.cn; Liang, Hongbin; Wang, Jing

    2014-08-01

    The microcrystalline Gd{sub 2}O{sub 3}:Eu{sup 3+} phosphors were synthesized by the hydrothermal method with post annealing treatment. The powder X-ray diffraction (XRD) indicated the phase transformation from cubic to monoclinic occurred at about 1673 K. The morphologies and sizes were characterized by scanning electron microscopy (SEM). It was found that the morphology of Gd{sub 2}O{sub 3}:Eu{sup 3+} was altered from nanorod to microparticle as the phase changed from cubic to monoclinic. In order to evaluate the effects of sites and phases on luminescence behaviors, the photoluminescence (PL) properties of both phases were investigated. Dominant red emission was observed due to an efficient energy transfer among the sites as well as the strong excitation of O{sup 2−}–Eu{sup 3+} charge transfer band. It was calculated that the monoclinic structure has a higher degree of distortion. More importantly, the phase transformation resulted in the red shift of the strongest emission peak of Eu{sup 3+} from 610.5 to 622.5 nm, closer to the optical transmission window for bioimaging. - Highlights: • Raising annealing temperature induces phase transformation from cubic to monoclinic. • Different phases and sites lead to distinct photoluminescence properties. • Monoclinic structure has higher degree of distortion and it is calculated. • Monoclinic phase emitting at longer wavelength is proposed for bioimaging.

  11. The extraction and effect in the system uranyl nitrate-dietyl ether-water

    International Nuclear Information System (INIS)

    Perez Luina, A.; Gutierrez Jodra, L.; Rius Miro, A.

    1960-01-01

    The solute transfer of uranyl nitrate from diethyl ether to water has been studied in a spray column using water as dispersed phase and a direction of extraction from ether to water. The column is 102 cm long and has a diameter of 4,7 cm. The entrances of the phases are 77 cm apart. The rates of flow of both phases have been used as variables and the concentration of the continuous phase has been determined at different heights. The curves of logarithm of concentration of the continuous phase vs. distance to interphase show the present of a drop of concentration in the entrance of the continuous phase. This depends on the rates of flow of the phases. No effect in the entrance of the dispersed phase has been found. (Author) 20 refs

  12. The final effect of extraction system in the uranyl nitrate-water-diethyl ether

    International Nuclear Information System (INIS)

    Perez Luina, A.; Gutierrez Jodra, L.; Miro, A. R.

    1957-01-01

    The solute transfer of uranyl nitrate from diallylether to water has been studied in a spray column using water as dispersed phase and a direction of extraction from ether to water. The column is 102 cm. long has a diameter of 4. 7 cm. The entrances of the phases are 7 7 cm. apart. The rates of flow of both phases have been used as variables and the concentration of the continuous phase has been determined; at different heights. The curves of logarithm of concentration of the continuous phase vs , distance to interphase show the presence of a drop of concentration in the entrance of the continuous phase. This depends on the rates of flow of the phases. No effect in the entrance of the dispersed phase has been found. (Author)

  13. Nano magnetic solid phase extraction for preconcentration of lead ions in environmental samples by a newly synthesized reagent.

    Science.gov (United States)

    Golshekan, Mostafa; Shariati, Shahab

    2013-01-01

    In this study, magnetite nanoparticles with particle size lower than 47 nm were synthesized and were applied for preconcentration of Pb2+ ions from aqueous solutions. To preconcentrate the Pb2+ ions, the surface of the synthesized nano particles was modified with sodium dodecyl sulfate (SDS) as an anionic surfactant. A new chelating agent (2-((E)-2-amino-4,5-dinitrophenylimino)methyl)phenol) was synthesized and used to form a very stable complex with Pb2+ ions. The lead ions formed complexes and were quantitatively extracted with SDS-coated magnetite nanoparticles. After magnetic separation of adsorbent, the adsorbent was eluted with 0.5% (v/v) HC1 in dimethyl sulfoxide (DMSO) prior to analysis by flame atomic absorption spectrometry (FAAS). Orthogonal array design (OAD) was used to study and optimize the different experimental parameters. Under the optimum conditions, enhancement factor up to 63.5 was achieved for extraction from only 10 mL of sample solution and the relative standard deviation (RSD %) of the method was lower than 2.8%. The obtained calibration curve was linear in the range of 1-300 pg L-' with reasonable linearity (r2 > 0.998). The limit of detection (LOD) based on S/N = 3 was 0.04 microg L(-1) for 10 mL sample volumes. Finally, applicability of the proposed method was successfully confirmed by preconcentration and determination of trace amounts of lead ions in environmental samples and satisfactory results were obtained.

  14. Uranyl soaps - thermal, electronic and infrared spectral study

    International Nuclear Information System (INIS)

    Solanki, A.K.; Bhandari, A.M.

    1981-01-01

    The electronic and infrared spectra and TGA thermogram of uranyl soaps (laurate, mystrate, palmitate and stearate) have been studied. The environment about the UO 2+ 2 ion would comprise two 'short bite' bidentate carboxylate groups and oxygen atoms bridging from adjacent carboxylic molecules. The uranyl soaps have UO 2+ 2 vibronic absorption (approx. equal to 22730 cm -1 ) in the range found for eight coordinate uranyl complexes. The greater resistance to thermal degradation (approx. equal to 300 0 C) of these soaps and their stepwise thermal degradation infer strong metal-ligand interaction. (orig.) [de

  15. Dehydration-driven evolution of topological complexity in ethylamonium uranyl selenates

    Energy Technology Data Exchange (ETDEWEB)

    Gurzhiy, Vladislav V., E-mail: vladgeo17@mail.ru [Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg (Russian Federation); Krivovichev, Sergey V. [Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg (Russian Federation); Tananaev, Ivan G. [Far Eastern Federal University, Suhanova st. 8, 690950 Vladivostok (Russian Federation)

    2017-03-15

    Single crystals of four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules, (C{sub 2}H{sub 8}N){sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)](H{sub 2}O) (I), (C{sub 2}H{sub 8}N){sub 3}[(UO{sub 2})(SeO{sub 4}){sub 2}(HSeO{sub 4})] (II), (C{sub 2}H{sub 8}N)[(UO{sub 2})(SeO{sub 4})(HSeO{sub 3})] (III), and (C{sub 2}H{sub 8}N)(H{sub 3}O)[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)] (IV) have been prepared by isothermal evaporation from aqueous solutions. Uranyl-containing 1D and 2D units have been investigated using topological approach and information-based complexity measurements that demonstrate the evolution of structural units and the increase of topological complexity with the decrease of H{sub 2}O content. - Graphical abstract: Single crystals of four novel uranyl selenate and selenite-selenate oxysalts with protonated ethylamine molecules have been prepared by isothermal evaporation from aqueous solutions. Structural analysis and information-based topological complexity calculations points to the possible sequence of crystalline phases formation, showing both topological and structural branches of evolution. - Highlights: • Single crystals of four novel uranyl oxysalts were prepared by evaporation method. • The graph theory was used for investigation of topologies of structural units. • Dehydration processes drives the evolution of topological complexity of 1D and 2D structural units.

  16. Thermal decomposition of ammonium diuranate, uranyl nitrate hexahydrate and uranyl peroxide

    International Nuclear Information System (INIS)

    Yulianto, T.; Mutiara, E.

    2011-01-01

    The behaviors of three types of starting powder had been investigated during their thermal decomposition processes in nitrogen, air, and hydrogen. The powder types were the products of uranyl nitrate precipitation, i.e. ADU (ammonium diuranate), UNH (uranyl nitrate hexahydrate), and UPO (uranyl peroxide). The objective of the investigation was to find out the best atmosphere that would result in good quality powder in a thermal decomposition process with the lowest temperature and the shortest period of time in order to reduce the cost of UO 2 powder preparation. Before the thermal decomposition process was initiated, all powder types were characterized for their crystal structures. The investigation was conducted by TG-DTA instrument at temperature up to 800°C and the heating rate of 10°C/minute. The crystal structures were identified by X-Ray Diffractometer with Cu-Ka radiation. The specific surface area of the powder was also observed using BET method, especially for the powder that underwent the process in hydrogen heated up to 800°C. The Results showed that the process took place faster in hydrogen, and UNH required lower thermal decomposition temperature in relations with other types of powder. (author)

  17. Quasirelativistic pseudopotential study of species isoelectronic to uranyl and the equatorial coordination of uranyl

    International Nuclear Information System (INIS)

    Pyykkoe, P.; Li, J.; Runeberg, N.

    1994-01-01

    The calculated trends of geometries and vibrational frequencies of several uranyl isoelectronic species, like the known NUN and CUO, and the unknown CUN - , NUO + , and NUF 2+ , are reported. The NUN and CUO results support the matrix spectroscopic assignments. The simplest example of equatorial coordination to uranyl is the C 2d species UO 3 . Its calculated vibrational frequencies also support matrix spectroscopic ones. We earlier suggested that the large range of uranyl bond lengths in UO 6 6- -type systems could be interpreted in terms of a open-quotes frozen, soft e g vibrational modeclose quotes. Further studies on UF 6 , U(OH) 6 , [(OUO)(F eq ) n ] (n-2) -, [(OUO)(NO 3 ) 3 ] - , and [(OUO)(CO 3 ) 3 ] 4- show only small variation of R ax as function of R eq . Thus, the all-oxide case is a special one, where all ligands are capable of single and multiple bonding. 44 refs., 10 figs., 7 tabs

  18. Adsorption of uranyl in SiO2 porous glass

    International Nuclear Information System (INIS)

    Benedetto, F. E.; Prado, M. O.

    2013-01-01

    Vitreous SiO 2 porous matrices can be used in many applications involving the uptake of chemical species on its solid surface. In this work, vitreous silica sponges were prepared from a sodium borosilicate glass manufactured in our laboratory. The product obtained was then separated into phases with subsequent leaching of the soluble phase rich in B and Na. The resulting porous matrices have a specific surface of 35 m2/gr. Adsorption of uranyl ions onto the SiO 2 porous surface was studied to evaluate the use of this material as a filter for treatment of uranium containing water. The effects of contact time, adsorbent mass and equilibrium concentration of solution were studied. The porous adsorbent exhibits a pseudo-second-order kinetic behavior. The sponges with adsorbed uranium were thermally sealed as a way of U immobilization. Retention of uranium was confirmed during the matrix sealing by TGA. Uranium concentration before and after adsorption tests were made by means of ICP-OES. For uranium concentration of 800 ppm, 72 hours contact time and pH of 3.5, the amount of uranium adsorbed was 21.06 ± 0.02 mg U per gram of vitreous porous SiO 2 . (author)

  19. Synthesis of microspheres of triuranium octaoxide by simultaneous water and nitrate extraction from ascorbate-uranyl sols

    International Nuclear Information System (INIS)

    Brykala, M.; Deptula, A.; Rogowski, M.; Lada, W.; Olczak, T.; Wawszczak, D.; Smolinski, T.; Wojtowicz, P.; Modolo, G.

    2014-01-01

    A new method for synthesis of uranium oxide microspheres (diameter <100 μm) has been developed. It is a variant of our patented Complex Sol-Gel Process, which has been used to synthesize high-quality powders of a wide variety of complex oxides. Starting uranyl-nitrate-ascorbate sols were prepared by addition of ascorbic acid to uranyl nitrate hexahydrate solution and alkalizing by aqueous ammonium hydroxide and then emulsified in 2-ethylhexanol-1 containing 1v/o SPAN-80. Drops of emulsion were firstly gelled by extraction of water by the solvent. Destruction of the microspheres during thermal treatment, owing to highly reactive components in the gels, requires modification of the gelation step by Double Extraction Process-simultaneously extraction of water and nitrates using Primene JMT, which completely eliminates these problem. Final step was calcination in air of obtained microspheres of gels to triuranium octaoxide. (author)

  20. Study of phase development and thermal stability in as synthesized TiO2 nanoparticles by laser pyrolysis: ethylene uptake and oxygen enrichment

    Science.gov (United States)

    Ilie, Alina Georgiana; Scarisoreanu, Monica; Dutu, Elena; Dumitrache, Florian; Banici, Ana-Maria; Fleaca, Claudiu Teodor; Vasile, Eugenia; Mihailescu, Ion

    2018-01-01

    Laser pyrolysis has proven a viable and trustworthy method of TiO2 nanoparticles fabrication, ensuring good quality and wide variety of nanoparticle morphologies and sizes. This work is aimed to phase control, experimentally studied, by parameter modulation, during one step laser pyrolysis synthesis or in combination with thermal annealing. High phase purity anatase and rutile TiO2 nanoparticles, oxygen abundant, are synthesized from TiCl4 and C2H4 gas mixtures, in the presence of air as oxygen donor, under CO2 laser radiation. The nano-titania samples are analyzed by X-ray Diffraction, EDAX, TEM and Raman spectroscopy and reveal good phase stability and distinct morphology. This study extends the method applicability onto rutile majoritarian TiO2 synthesis and generation of thermally stable anatase titania, a well-known catalyst.

  1. Synthesized research report in the second mid-term research phase. Mizunami Underground Research Laboratory project, Horonobe Underground Research Laboratory project and geo-stability project (Translated document)

    International Nuclear Information System (INIS)

    Hama, Katsuhiro; Sasao, Eiji; Iwatsuki, Teruki; Onoe, Hironori; Sato, Toshinori; Yasue, Kenichi; Asamori, Koichi; Niwa, Masakazu; Osawa, Hideaki; Nagae, Isako; Natsuyama, Ryoko; Fujita, Tomoo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Takeda, Masaki; Aoyagi, Kazuhei; Nakayama, Masashi; Miyakawa, Kazuya; Ito, Hiroaki; Ohyama, Takuya; Senba, Takeshi; Amano, Kenji

    2016-08-01

    We have synthesized the research results from the Mizunami/Horonobe Underground Research Laboratories (URLs) and geo-stability projects in the second mid-term research phase. This report can be used as a technical basis for the Nuclear Waste Management Organization of Japan/Regulator at each decision point from siting to beginning of disposal (Principal Investigation to Detailed Investigation Phase). High-quality construction techniques and field investigation methods have been developed and implemented, which will be directly applicable to the National Disposal Program (together with general assessments of hazardous natural events and processes). Acquisition of technical knowledge on decisions of partial backfilling and final closure from actual field experiments in the Mizunami/Horonobe URLs will be crucial as the main theme for the next phases. (author)

  2. Sodium dodecyl sulfate coated alumina modified with a new Schiff's base as a uranyl ion selective adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Tashkhourian, J., E-mail: tashkhourian@susc.ac.ir [Department of Chemistry, College of Science, Shiraz University, 71454 Shiraz (Iran, Islamic Republic of); Moradi Abdoluosofi, L.; Pakniat, M. [Department of Chemistry, Faculty of Science, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Montazerozohori, M. [Department of Chemistry, Faculty of Science, Yasouj University, Yasouj (Iran, Islamic Republic of)

    2011-03-15

    A simple and selective method was used for the preconcentration and determination of uranium(VI) by solid-phase extraction (SPE). In this method, a column of alumina modified with sodium dodecyl sulfate (SDS) and a new Schiff's base ligand was prepared for the preconcentration of trace uranyl(VI) from water samples. The uranium(VI) was completely eluted with HCl 2 M and determined by a spectrophotometeric method with Arsenazo(III). The preconcentration steps were studied with regard to experimental parameters such as amount of extractant, type, volume and concentration of eluent, pH, flow rate of sample source and tolerance limit of diverse ions on the recovery of uranyl ion. A preconcentration factor more than 200 was achieved and the average recovery of uranyl(VI) was 99.5%. The relative standard deviation was 1.1% for 10 replicate determinations of uranyl(VI) ion in a solution with a concentration of 5 {mu}g mL{sup -1}. This method was successfully used for the determination of spiked uranium in natural water samples.

  3. Synthesizing single-phase β-FeSi2 via ion beam irradiations of Fe/Si bilayers

    International Nuclear Information System (INIS)

    Milosavljevic, M.; Dhar, S.; Schaaf, P.; Bibic, N.; Lieb, K.P.

    2001-01-01

    This paper presents results on the direct synthesis of the β-FeSi 2 phase by ion beam mixing of Fe/Si bilayers with Xe ions. The influence of the substrate temperature, ion fluence and energy on the growth of this phase was investigated using Rutherford backscattering (RBS), X-ray diffraction (XRD) and conversion electron Moessbauer spectroscopy (CEMS). Complete growth of single-phase β-FeSi 2 was achieved by 205 keV Xe ion irradiation to a fluence of 2x10 16 ions/cm 2 at 600 deg. C. We propose a two-step reaction mechanism involving thermal and ion beam energy deposition

  4. Colorimetric peroxidase mimetic assay for uranyl detection in sea water

    KAUST Repository

    Zhang, Dingyuan; Chen, Zhuo; Omar, Haneen; Deng, Lin; Khashab, Niveen M.

    2015-01-01

    Uranyl (UO2 2+) is a form of uranium in aqueous solution that represents the greatest risk to human health because of its bioavailability. Different sensing techniques have been used with very sensitive detection limits especially the recently

  5. Uranyl phosphate mineral in Gapyeong area

    International Nuclear Information System (INIS)

    Chung, S.J.

    1980-01-01

    An uranyl phosphate crystal from Gapeong area is studied by means of single crystal x-ray diffraction and electron microscopic qualitative analysis of chemical contents. The crystal is identified as meta-ankoleite which has a unit cell of super structure with a=b=6.99 A, c=17.69 A and space group P4 2 22. There exists some indication in the total fluorescent spectrum of the sample that potassium may be partially substituted by calcium. The chemical formula of this meta-ankoleite may be expressed by Ksub(1-2x)Casub(x)(UO 2 PO 4 ) (H 2 O)sub(3-x). (Author)

  6. Glutathione attenuates uranyl toxicity in Lactococcus lactis

    Energy Technology Data Exchange (ETDEWEB)

    Fahmy, Karim; Oertel, Jana [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biophysics; Obeid, M. [Technische Univ. Dresden (Germany); Solioz, M. [Bern Univ. (Switzerland)

    2017-06-01

    We investigated the role of intracellular glutathione (GSH), which in a large number of taxa plays a role in the protection against the toxicity of heavy metals. Anaerobically grown Lactococcus lactis containing an inducible GSH synthesis pathway was used as a model organism allowing the study of GSH-dependent uranyl detoxification without interference from additional reactive oxygen species. Microcalorimetric measurements of the metabolic heat showed that intracellular GSH attenuates the toxicity of uranium at a concentration in the range of 10-150 μM. Isothermal titration calorimetry revealed the endothermic binding of U(VI) to the carboxyl group(s) of GSH. The data indicate that the primary detoxifying mechanism is the intracellular sequestration of carboxyl-coordinated U(VI) into an insoluble complex with GSH.

  7. Glutathione attenuates uranyl toxicity in Lactococcus lactis

    International Nuclear Information System (INIS)

    Fahmy, Karim; Oertel, Jana; Solioz, M.

    2017-01-01

    We investigated the role of intracellular glutathione (GSH), which in a large number of taxa plays a role in the protection against the toxicity of heavy metals. Anaerobically grown Lactococcus lactis containing an inducible GSH synthesis pathway was used as a model organism allowing the study of GSH-dependent uranyl detoxification without interference from additional reactive oxygen species. Microcalorimetric measurements of the metabolic heat showed that intracellular GSH attenuates the toxicity of uranium at a concentration in the range of 10-150 μM. Isothermal titration calorimetry revealed the endothermic binding of U(VI) to the carboxyl group(s) of GSH. The data indicate that the primary detoxifying mechanism is the intracellular sequestration of carboxyl-coordinated U(VI) into an insoluble complex with GSH.

  8. Complexes of uranyl nitrate with 2,6-pyridinedicarboxamides: synthesis, crystal structure, and DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Alyapyshev, Mikhail; Babain, Vasiliy [ITMO University, 49, Kronverksky pr., 197101, St. Petersburg (Russian Federation); ThreeArc Mining Ltd., 5, Stary Tolmachevskiy per., 115184, Moscow (Russian Federation); Tkachenko, Lyudmila; Lumpov, Alexander [Khlopin Radium Institute, 28, 2nd Murinskiy pr., 194021, St. Petersburg (Russian Federation); Gurzhiy, Vladislav; Zolotarev, Andrey; Dar' in, Dmitriy [St. Petersburg State University, 7-9, Universitetskaya nab., 199034, St. Petersburg (Russian Federation); Ustynyuk, Yuriy; Gloriozov, Igor [M.V. Lomonosov Moscow State University, 119991, Moscow (Russian Federation); Paulenova, Alena [Department of Nuclear Engineering, Oregon State University, Corvallis, OR (United States)

    2017-05-04

    Two complexes of uranyl nitrate with N,N,N',N'-tetrabutyl-2,6-pyridinedicarboxamide (TBuDPA) and N,N'-diethyl-N,N'-diphenyl-2,6-pyridinedicarboxamide (EtPhDPA) were synthesized and studied. The complex of tetraalkyl-2,6-pyridinedicarboxamide with metal nitrate was synthesized for the first time. XRD analysis revealed the different type of complexation: a 1:1 metal:ligand complex for EtPhDPA and complex with polymeric structure for TBuDPA. The quantum chemical calculations (DFT) confirm that both ligands form the most stable complexes that match the minimal values pre-organization energy of the ligands. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Enantioselective syntheses of aeruginosin 298-A and its analogues using a catalytic asymmetric phase-transfer reaction and epoxidation.

    Science.gov (United States)

    Ohshima, Takashi; Gnanadesikan, Vijay; Shibuguchi, Tomoyuki; Fukuta, Yuhei; Nemoto, Tetsuhiro; Shibasaki, Masakatsu

    2003-09-17

    We developed a versatile synthetic process for aeruginosin 298-A as well as several attractive analogues, in which all stereocenters were controlled by a catalytic asymmetric phase-transfer reaction and epoxidation. Furthermore, drastic counteranion effects in phase-transfer catalysis were observed for the first time, making it possible to three-dimensionally fine-tune the catalyst (ketal part, aromatic part, and counteranion).

  10. Thermodynamics of dehydration process of uranyl nitrate pentahydrate of thorium

    International Nuclear Information System (INIS)

    Khamidov, F.A.; Mirsaidov, I.U.; Nazarov, K.M.; Nasriddinov, S.K.; Badalov, A.B.

    2010-01-01

    Present article is devoted to thermodynamics of dehydration process of uranyl nitrate pentahydrate of thorium. The results of researches of dehydration process of uranyl nitrate pentahydrate of thorium Th(NO_3)_4·5H_2O were considered. The researches were carried out by means of tensimeter method with membrane zero-manometer under equilibrium conditions and at 300-450 K temperature ranges. The thermodynamic characteristics of dehydration process of initial crystalline hydrate was defined.

  11. Radiolysis studies of uranyl nitrate solution in nitric acid medium

    International Nuclear Information System (INIS)

    Siri, Sandra; Mondino, Angel V.

    2005-01-01

    The radiolysis of acidic uranyl nitrate solutions was investigated using Co-60 gamma radiation. Hydrogen peroxide was determined as a function of increasing dose. The UV-vis absorption spectra of the irradiated solutions were measured and the spectral changes were analyzed. The increasing dose increases the absorbance intensities, possibly by an increment in nitrate concentration produced by radiolysis, which can originate the formation of different uranyl complexes in solution. (author)

  12. Magnetic response of polycrystalline YBaCo4O7+δ synthesized through the physical and chemical route: The role of phase inhomogeneities

    International Nuclear Information System (INIS)

    Vallejos, E.; Galeano, V.; Gómez, L.; Izquierdo, J.L.; Montoya, J.F.; Mera, J.; Córdoba, C.; Gómez, A.; Paucar, C.; Morán, O.

    2014-01-01

    Polycrystalline YBaCo 4 O 7+δ samples were obtained through a standard solid state reaction, and their structural, morphological, electrical, and magnetic properties are carefully studied. The X-ray powder diffraction (XRD) patterns showed reflections of a pure hexagonal structure (space group P6 3 mc) with lattice parameters being very close to those reported in the literature. Although XRD analysis showed that the main phase present is 114, the presence of secondary phases could not be ruled out based solely on the XRD characterization. Indeed, sensitive SQUID magnetic measurements showed that the samples were affected by very small quantities of the 112 phase (YBaCo 2 O 5.5 ), which typically manifests itself through a conspicuous increase in the magnetization at∼300 K. The results achieved corroborated the predictions concerning the difficulty of stabilizing the 114 phase when synthesized via the standard solid-state reaction. With this in mind, we next attempted to obtain the compound with improved phase purity. In so doing, the YBaCo 4 O 7+δ compound was synthesized through a wet chemistry method based on a citrates route. The XRD patterns recorded for these samples revealed well-defined peaks corresponding to a pure hexagonal structure. More interestingly, SQUID measurements show no sign of features in the M(T) curve at temperatures as low as∼80 K. This result was consistent with the magnetic behavior observed in YBaCo 4 O 7+δ single-crystals. At temperatures below∼80 K, a clear feature was observed which seemed to correlate with a transition into an antiferromagnetic state. Isothermal magnetization recorded at 70 K showed that field-induced effects manifested themselves through the appearance of a ferromagnetic-like component. This ferromagnetic component may arise from spin canting of the underlying antiferromagnetic state or through field-induced structural transition (at least at local scale). Although a definitive interpretation of the in

  13. Magnetic response of polycrystalline YBaCo{sub 4}O{sub 7+δ} synthesized through the physical and chemical route: The role of phase inhomogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Vallejos, E. [Universidad de Nariño, Centro de Materiales Avanzados, Torobajo, Pasto (Colombia); Galeano, V.; Gómez, L.; Izquierdo, J.L.; Montoya, J.F. [Universidad Nacional de Colombia, Campus Medellín, Departamento de Física, Laboratorio de Materiales Cerámicos y Vítreos, A.A. 568 Medellín (Colombia); Mera, J.; Córdoba, C. [Universidad de Nariño, Centro de Materiales Avanzados, Torobajo, Pasto (Colombia); Gómez, A. [Universidad Nacional de Colombia, Campus Medellín, Facultad de Minas, Laboratorio de caracterización de materiales, A.A. 568 Medellín (Colombia); Paucar, C. [Universidad Nacional de Colombia, Campus Medellín, Departamento de Física, Laboratorio de Materiales Cerámicos y Vítreos, A.A. 568 Medellín (Colombia); Morán, O., E-mail: omoranc@unal.edu.co [Universidad Nacional de Colombia, Campus Medellín, Departamento de Física, Laboratorio de Materiales Cerámicos y Vítreos, A.A. 568 Medellín (Colombia)

    2014-06-01

    Polycrystalline YBaCo{sub 4}O{sub 7+δ} samples were obtained through a standard solid state reaction, and their structural, morphological, electrical, and magnetic properties are carefully studied. The X-ray powder diffraction (XRD) patterns showed reflections of a pure hexagonal structure (space group P6{sub 3}mc) with lattice parameters being very close to those reported in the literature. Although XRD analysis showed that the main phase present is 114, the presence of secondary phases could not be ruled out based solely on the XRD characterization. Indeed, sensitive SQUID magnetic measurements showed that the samples were affected by very small quantities of the 112 phase (YBaCo{sub 2}O{sub 5.5}), which typically manifests itself through a conspicuous increase in the magnetization at∼300 K. The results achieved corroborated the predictions concerning the difficulty of stabilizing the 114 phase when synthesized via the standard solid-state reaction. With this in mind, we next attempted to obtain the compound with improved phase purity. In so doing, the YBaCo{sub 4}O{sub 7+δ} compound was synthesized through a wet chemistry method based on a citrates route. The XRD patterns recorded for these samples revealed well-defined peaks corresponding to a pure hexagonal structure. More interestingly, SQUID measurements show no sign of features in the M(T) curve at temperatures as low as∼80 K. This result was consistent with the magnetic behavior observed in YBaCo{sub 4}O{sub 7+δ} single-crystals. At temperatures below∼80 K, a clear feature was observed which seemed to correlate with a transition into an antiferromagnetic state. Isothermal magnetization recorded at 70 K showed that field-induced effects manifested themselves through the appearance of a ferromagnetic-like component. This ferromagnetic component may arise from spin canting of the underlying antiferromagnetic state or through field-induced structural transition (at least at local scale). Although a

  14. Probing the influence of N-donor capping ligands on supramolecular assembly in molecular uranyl materials

    Energy Technology Data Exchange (ETDEWEB)

    Carter, Korey P.; Kalaj, Mark; Cahill, Christopher L. [Department of Chemistry, The George Washington University, Washington, DC (United States)

    2016-01-15

    The syntheses and crystal structures of six new compounds containing the UO{sub 2}{sup 2+} cation, 3,5-dichlorobenzoic acid, and a chelating N-donor [2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (dimethylphen), 2,2{sup '}:6{sup '},2''-terpyridine (terpy), 4{sup '}-chloro-2,2{sup '}:6{sup '},2''-terpyridine (Cl-terpy), or 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ)] are reported. Single-crystal X-ray diffraction analysis of these materials enabled the exploration of the structural relationship between the benzoic acids and the chelating N-donor as well as providing a platform to evaluate the effects of ligand choice on uranyl hydrolysis and subsequent oligomerization. At an unadjusted pH (ca. 3), a mix of uranyl monomers and dimers are observed, dimer formation resulting from both bridging carboxylate linkers and hydroxo bridges. Assembly by halogen- and hydrogen-bonding interactions as well as π-π interactions was observed depending on the experimental conditions utilized. Further, spectroscopic characterization (both vibrational and luminescence) of complexes 1, 4, and 5 to explore the effects of the electron-donating ability of the capping ligand on the corresponding uranyl luminescence and vibrational spectra suggests that there is a relationship between the observed bathochromic shifts and the electron-donating ability of the capping ligands. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Synthesis and X-ray diffraction study of new uranyl malonate and oxalate complexes with carbamide

    Energy Technology Data Exchange (ETDEWEB)

    Medvedkov, Ya. A.; Serezhkina, L. B., E-mail: Lserezh@samsu.ru [Samara State University (Russian Federation); Grigor’ev, M. S. [Russian Academy of Sciences, Frumkin Institute of Physical Chemistry and Electrochemistry (Russian Federation); Serezhkin, V. N. [Samara State University (Russian Federation)

    2016-05-15

    Two new malonate-containing uranyl complexes with carbamide of the formulas [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 2}] (I) and [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 3}] (II), where Urea is carbamide, and one uranyl oxalate complex of the formula [UO{sub 2}(C{sub 2}O{sub 4})(Urea){sub 3}] (III) were synthesized, and their crystals were studied by X-ray diffraction. The main structural units in crystals I are the electroneutral chains [UO{sub 2}(C{sub 3}H{sub 2}O{sub 4})(Urea){sub 2}]{sub ∞} belonging to the crystal-chemical group AT{sup 11}M{sub 2}{sup 1} (A = UO{sub 2}{sup 2+}, T{sup 11} = C{sub 3}H{sub 2}O{sub 4}{sup 2-}, M{sup 1} = Urea) of uranyl complexes. Crystals II and III are composed of the molecular complexes [UO{sub 2}(L)(Urea){sub 3}], where L = C{sub 3}H{sub 2}O{sub 4}{sup 2-} or C{sub 2}O{sub 4}{sup 2-}, belonging to the crystal-chemical group AB{sup 01}M{sub 3}{sup 1} (A = UO{sub 2}{sup 2+}, B{sup 01} = C{sub 3}H{sub 2}O{sub 4}{sup 2-} or C{sub 2}O{sub 4}{sup 2-}, M{sup 1} = Urea). The characteristic features of the packing of the uranium-containing complexes are discussed in terms of molecular Voronoi–Dirichlet polyhedra. The effect of the Urea: U ratio on the structure of uranium-containing structural units is considered.

  16. Probing the influence of N-donor capping ligands on supramolecular assembly in molecular uranyl materials

    International Nuclear Information System (INIS)

    Carter, Korey P.; Kalaj, Mark; Cahill, Christopher L.

    2016-01-01

    The syntheses and crystal structures of six new compounds containing the UO 2 2+ cation, 3,5-dichlorobenzoic acid, and a chelating N-donor [2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (dimethylphen), 2,2 ' :6 ' ,2''-terpyridine (terpy), 4 ' -chloro-2,2 ' :6 ' ,2''-terpyridine (Cl-terpy), or 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ)] are reported. Single-crystal X-ray diffraction analysis of these materials enabled the exploration of the structural relationship between the benzoic acids and the chelating N-donor as well as providing a platform to evaluate the effects of ligand choice on uranyl hydrolysis and subsequent oligomerization. At an unadjusted pH (ca. 3), a mix of uranyl monomers and dimers are observed, dimer formation resulting from both bridging carboxylate linkers and hydroxo bridges. Assembly by halogen- and hydrogen-bonding interactions as well as π-π interactions was observed depending on the experimental conditions utilized. Further, spectroscopic characterization (both vibrational and luminescence) of complexes 1, 4, and 5 to explore the effects of the electron-donating ability of the capping ligand on the corresponding uranyl luminescence and vibrational spectra suggests that there is a relationship between the observed bathochromic shifts and the electron-donating ability of the capping ligands. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Characterization of Cr-rich Cr-Sb multilayer films: Syntheses of a new metastable phase using modulated elemental reactants

    International Nuclear Information System (INIS)

    Regus, Matthias; Mankovsky, Sergiy; Polesya, Svitlana; Kuhn, Gerhard; Ditto, Jeffrey; Schürmann, Ulrich; Jacquot, Alexandre; Bartholomé, Kilian; Näther, Christian; Winkler, Markus; König, Jan D.; Böttner, Harald; Kienle, Lorenz; Johnson, David C.; Ebert, Hubert; Bensch, Wolfgang

    2015-01-01

    The new metastable compound Cr 1+x Sb with x up to 0.6 has been prepared via a thin film approach using modulated elemental reactants and investigated by in-situ X-ray reflectivity, X-ray diffraction, differential scanning calorimetry, energy dispersive X-ray analysis as well as transmission electron microscopy and atomic force microscopy. The new Cr-rich antimonide crystallizes in a structure related to the Ni 2 In-type structure, where the crystallographic position (1/3, 2/3, 3/4) is partially occupied by excess Cr. The elemental layers of the pristine material interdiffused significantly before Cr 1+x Sb crystallized. A change in the activation energy was observed for the diffusion process when crystal growth starts. First-principles electronic structure calculations provide insight into the structural stability, magnetic properties and resistivity of Cr 1+x Sb. - Graphical abstract: 1 amorphous multilayered film 2 interdiffused amorphous film 3 metastable crystalline phase 4 thermodynamic stable phase (and by-product). - Highlights: • Interdiffusion of amorphous Cr and Sb occurs before crystallization. • Crystallization of a new metastable phase Cr 1.6 Sb in Ni 2 In-type structure. • The new Cr-rich phase shows half-metallic behavior

  18. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    Energy Technology Data Exchange (ETDEWEB)

    François, B. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France); INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Calosso, C. E.; Micalizio, S. [INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Abdel Hafiz, M.; Boudot, R. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France)

    2015-09-15

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be −109 and −141 dB rad{sup 2}/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is −105 and −138 dB rad{sup 2}/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10{sup −14} for the Cs cell clock and 2 × 10{sup −14} for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10{sup −15} level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  19. Effect of ambient pressure on the crystalline phase of nano TiO2 particles synthesized by a dc thermal plasma reactor

    International Nuclear Information System (INIS)

    Banerjee, I.; Karmakar, Soumen; Kulkarni, Naveen V.; Nawale, Ashok B.; Mathe, V. L.; Das, A. K.; Bhoraskar, S. V.

    2010-01-01

    The synthesis of nanoparticles of titanium dioxide (TiO 2 ) with varying percentages of anatase and rutile phases is reported. This was achieved by controlling the operating pressure in a transferred-arc, direct current thermal plasma reactor in which titanium vapors are evaporated, and then exposed to ambient oxygen. The average particle size remained around 15 nm in each case. The crystalline structure of the as-synthesized nanoparticles of TiO 2 was studied with X-ray diffraction analysis; whereas the particle morphology was investigated with the help of transmission electron microscopy. The precursor species responsible for the growth of these nanoparticles was studied with the help of optical emission spectroscopy. As inferred from the X-ray diffraction analysis, the relative abundance of anatase TiO 2 was found to be dominant when synthesized at 760 Torr, and the same showed a decreasing trend with decreasing chamber pressure. The study also reveals that anatase TiO 2 is a more effective photocatalytic agent in degrading methylene blue by comparison to its rutile phase.

  20. Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

    KAUST Repository

    Biausque, Gregory; Laveille, Paco; Anjum, Dalaver H.; Caps, Valerie; Basset, Jean-Marie

    2015-01-01

    Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

  1. Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

    KAUST Repository

    Biausque, Gregory

    2015-04-28

    Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

  2. Tetragonal-cubic phase boundary in nanocrystalline ZrO2-Y2O3 solid solutions synthesized by gel-combustion

    International Nuclear Information System (INIS)

    Fabregas, Ismael O.; Craievich, Aldo F.; Fantini, Marcia C.A.; Millen, Ricardo P.; Temperini, Marcia L.A.; Lamas, Diego G.

    2011-01-01

    Research highlights: → Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO 2 -Y 2 O 3 nanopowders, that exhibit the presence at room temperature of three different phases depending on Y 2 O 3 content, namely two tetragonal forms (t' and t'') and the cubic phase. → Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. → The crystallographic features of ZrO 2 -Y 2 O 3 nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. → Compositional t'/t'' and t''/cubic phase boundaries are located at (9 ± 1) and (10.5 ± 0.5) mol% Y 2 O 3 , respectively. → For the whole series of nanocrystalline ZrO 2 -Y 2 O 3 solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO 2 -Y 2 O 3 solid solutions, the presence at room temperature of three different phases depending on Y 2 O 3 content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO 2 -Y 2 O 3 solid solutions exhibit the same phases reported in the literature for compositionally homogeneous materials containing larger (micro

  3. Tetragonal-cubic phase boundary in nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions synthesized by gel-combustion

    Energy Technology Data Exchange (ETDEWEB)

    Fabregas, Ismael O. [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Craievich, Aldo F.; Fantini, Marcia C.A. [Instituto de Fisica, Universidade de Sao Paulo, Travessa R da Rua do Matao, No. 187, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Millen, Ricardo P.; Temperini, Marcia L.A. [Instituto de Quimica, Universidade de Sao Paulo, Avenida Prof. Lineu Prestes 748, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Lamas, Diego G., E-mail: dlamas@uncoma.edu.ar [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Laboratorio de Caracterizacion de Materiales, Facultad de Ingenieria, Universidad Nacional del Comahue, Buenos Aires 1400, (8300) Neuquen Capital, Prov. de Neuquen (Argentina)

    2011-04-21

    Research highlights: > Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders, that exhibit the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms (t' and t'') and the cubic phase. > Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. > The crystallographic features of ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. > Compositional t'/t'' and t''/cubic phase boundaries are located at (9 {+-} 1) and (10.5 {+-} 0.5) mol% Y{sub 2}O{sub 3}, respectively. > For the whole series of nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions, the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid

  4. PULSE SYNTHESIZING GENERATOR

    Science.gov (United States)

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  5. Kinetic of liquid-liquid extraction for uranyl nitrate and actinides (III) and lanthanides (III) nitrates by amide extractants

    International Nuclear Information System (INIS)

    Toulemonde, V.; CEA Centre d'Etudes de la Vallee du Rhone, 30 -Marcoule

    1995-01-01

    The kinetics of liquid-liquid extraction by amide extractants have been investigated for uranyl nitrate (monoamide extractants), actinides (III) and lanthanides (III) nitrates (diamide extractants). The transfer of the metallic species from the aqueous phase to the organic phase was studied using two experimental devices: ARMOLLEX (Argonne Modified Lewis cell for Liquid Liquid Extraction) and RSC (Rotating Stabilized Cell). The main conclusions are: for the extraction of uranyl nitrate by DEHDMBA monoamide, the rate-controlling step is the complexation of the species at the interface of the two liquids. Thus, an absorption-desorption (according to Langmuir theory) reaction mechanism was proposed; for the extraction of actinides (III) and lanthanides (III) nitrates in nitric acid media by DMDBTDMA diamide, the kinetic is also limited by interfacial reactions. The behavior of Americium and Europium is very similar as fare as their reaction kinetics are concerned. (author)

  6. Study on the transport behavior of uranyl nitrate in aqueous and non-aqueous systems

    International Nuclear Information System (INIS)

    Roesel, B.

    1985-01-01

    The analytical ultracentrifuge has proven itself through diffusion measurements to be well suited for studying radioactive compounds. In the framework of this paper the extent to which the UV and schlieren optics of an analytical ultracentrifuge can be used for extraction-kinetic tests was tested. With this method there is also the possibility of determining the distribution coefficients right at the phase boundary. The results show the good possibility of application of the absorption and schlieren optics to the study of the transport behavior of uranyl nitrate in practice oriented solutions. (orig.) [de

  7. Effect of n-octanol on -uranyl extraction by tri-n-octylammonium sulfate

    International Nuclear Information System (INIS)

    Ochkin, A.V.; Kudrov, A.N.

    1984-01-01

    The effect of n-octanol on the extraction of uranyl sulfate by solutions of tri-n-octylamine sulfate in benzene has been studied. With the increase of alcohol concentration the coefficient of uranium distribution passes through the maximum. At low alcohol concentrations a decrease in water content in the organic phase is observed. It is shown that the increase in ammonium salt activity in replacement of part of hydrate At high alcohol concentration the decrease in uranium distribution coefficients is observed, which is related to TOA sulfate solvation by alcohol

  8. Thermal Analysis of the Decomposition of Ammonium Uranyl Carbonate (AUC) in Different Atmospheres

    DEFF Research Database (Denmark)

    Hälldahl, L.; Sørensen, Ole Toft

    1979-01-01

    The intermediate products formed during thermal decomposition of ammonium uranyl carbonate (AUC) in different atmospheres, (air, helium and hydrogen) have been determined by thermal analysis, (TG, and DTA) and X-ray analysis. The endproducts observed are U3O8 and UO2 in air/He and hydrogen, respe......, respectively. The following intermediate products were observed in all atmospheres: http://www.sciencedirect.com.globalproxy.cvt.dk/cache/MiamiImageURL/B6THV-44K80TV-FB-1/0?wchp=dGLzVlz-zSkWW X-ray diffraction analysis showed that these phases were amorphous....

  9. NMR studies of hydrogen diffusion in hydrogen uranyl phosphate tetrahydrate (HUP)

    International Nuclear Information System (INIS)

    Metcalfe, K.

    1988-01-01

    1 H NMR spin-lattice relaxation times, T 1 (Zeeman) and T 1p (rotating frame) and spin-spin relaxation times, T 2 , and 31 P NMR solid-echoes are reported for phase I and II of hydrogen uranyl phosphate tetrahydrate (HUP) at temperatures in the range 200-323 K. The spectral density functions extracted from the measured relaxation times for phases I and II are consistent with a 2D diffusion mechanism for hydrogen motion. 31 P second moments determined from the solid-echoes show that all the hydrogens diffuse rapidly in phase I, and that the hydrogen-bond site nearest to the phosphate oxygen is not occupied in phase II. The mechanism for diffusion in phase II is discussed. 30 refs.; 6 figs.; 2 tabs

  10. Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

    Directory of Open Access Journals (Sweden)

    Mahdi ES

    2011-06-01

    Full Text Available Elrashid Saleh Mahdi1, Mohamed HF Sakeena1, Muthanna F Abdulkarim1, Ghassan Z Abdullah1,3, Munavvar Abdul Sattar2, Azmin Mohd Noor11Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia; 3Department of Pharmaceutical Technology, International Medical University, Bukit Jalil, Kuala Lumpur, MalaysiaBackground: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature.Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters.Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant

  11. Efficient tetracycline adsorption and photocatalytic degradation of rhodamine B by uranyl coordination polymer

    Science.gov (United States)

    Ren, Ya-Nan; Xu, Wei; Zhou, Lin-Xia; Zheng, Yue-Qing

    2017-07-01

    Two mixed uranyl-cadmium malonate coordination polymers [(UO2)2Cd(H-bipy)2(mal)4(H2O)2]·4H2O 1 and [(UO2)Cd(bipy)(mal)2]·H2O 2 (H2mal = malonic acid, bipy =4,4‧-bipyridine) have been synthesized in room temperature. Compound 1 represents a one-dimensional (1D) chain assembly of Cd(II) ions, uranyl centers and malonate ligands. Compound 2 exhibits a two-dimensional (2D) 2D +2D → 3D polycatenated framework based on inclined interlocked 2D 44 sql grids. The two compounds have been characterized by elemental analysis, IR and UV-vis spectroscopy, thermal analysis, powder X-ray diffraction and photoluminescence spectroscopy. And the ferroelectric property of 2 also has been studied. Moreover, compound 2 exhibits good photocatalytic activity for dye degradation under UV light and is excellent adsorbent for removing tetracycline antibiotics in the aqueous solution.

  12. Syntheses and modulations in the chromatin contents of histones H1/sup o/ and H1 during G1 and S phases in Chinese hamsters cells

    International Nuclear Information System (INIS)

    D'Anna, J.A.; Gurley, L.R.; Tobey, R.A.

    1982-01-01

    Flow cytometry, conventional autoradiography, and autoradiography employing high concentrations of high specific activity [ 3 H]thymidine indicate that (1) treatment of Chinese hamster ovary (line CHO) cells with butyrate truly blocks cells in G 1 and (2) cells blocked in G 1 by isoleucine deprivation remain blocked in G 1 when they are released into complete medium containing butyrate. Measurements of H1/sup o/ content relative to core histones and H1/sup o/:H1 ratios indicate that H1/sup o/ is enhanced somewhat in G 1 cells arrested by isoleucine deprivation; however, (1) treatment with butyrate greatly increases the H1/sup o/ content in G 1 -blocked cells, and (2) the enhancement is very sensitive to butyrate concentration. Measurements of relative histone contents in the isolated chromatin of synchronized cultures also suggest that the acid-soluble content of histone H1 (relative to core histones) becomes greatly depleted in the isolated chromatin when synchronized cells are blocked in early S phase by sequential use of isoleucine deprivation and hydroxyurea blockade. We also have measured [ 3 H]lysine incorporation, various protein ratios, and relative rates of deposition of newly synthesized H1/sup o/, H1, and H4 onto chromatin during G 1 and S in the absence of butyrate. The results suggest a dynamic picture of chromatin organization in which (1) newly synthesized histone H1/sup o/ binds to chromatin during traverse of G 1 and S phases and (2) histone H1 dissociates from (or becomes loosely bound to) chromatin during prolonged early S-phase block with hydroxyurea

  13. G1- and S-phase syntheses of histones H1 and H1o in mitotically selected CHO cells: utilization of high-performance liquid chromatography

    International Nuclear Information System (INIS)

    D'Anna, J.A.; Thayer, M.M.; Tobey, R.A.; Gurley, L.R.

    1985-01-01

    The authors have employed high-performance liquid chromatography (HPLC) to investigate the syntheses of histones H1 and H1o as synchronized cells traverse from mitosis to S phase. Chinese hamster (line CHO) cells were synchronized by mitotic selection, and, at appropriate times, they were pulse labeled for 1 h with [ 3 H]lysine. Histones H1 and H1o were extracted by blending radiolabeled and carrier cells directly in 0.83 M HC1O 4 ; the total HC1O 4 -soluble, Cl 3 CCO 2 H-precipitable proteins were then separated by a modification of an HPLC system employing three mu Bondapak reversed-phase columns. These procedures (1) produce minimally perturbed populations of synchronized proliferating cells and (2) maximize the recovery of radiolabeled histones during isolation and analysis. Measurements of rates of synthesis indicate that the rate of H1 synthesis increases as cells traverse from early to mid G1; as cells enter S phase, the rate of H1 synthesis increases an additional congruent to 22-fold and is proportional to the number of S-phase cells. In contrast to H1, the rate of H1o synthesis is nearly constant throughout G1. As cells progress into S phase, the rate of H1o synthesis increases so that it also appears to be proportional to the number of S-phase cells. Except for the first 1-2 h after mitotic selection, these results are similar to those obtained when cells are synchronized in G1 with the isoleucine deprivation procedure

  14. Orientational order and dynamics of water in bulk and in aqueous solutions of uranyl ions

    International Nuclear Information System (INIS)

    Chopra, Manish; Choudhury, Niharendu

    2014-01-01

    Molecular dynamics simulations in canonical ensemble of aqueous solutions of uranyl nitrate and bulk water at ambient condition have been carried out to investigate orientational order and dynamics of water. The orientational distributions of water around a central water molecule in bulk water and around a uranyl ion in an aqueous uranyl solution have been calculated. Orientational dynamics of water in bulk and in aqueous uranyl nitrate solution have also been analysed. (author)

  15. Uranyl ion transport across tri-n-butyl phosphate/n-dodecane liquid membranes

    International Nuclear Information System (INIS)

    Shukla, J.P.; Misra, S.K.

    1991-01-01

    Carrier-facilitated transport of uranium (VI) against its concentration gradient from aqueous nitrate acidic solutions across organic bulk liquid membranes (BLM) and supported liquid membranes (SLM) containing TBP as the mobile carrier and n-dodecane as the membrane solvent was investigated. Extremely dilute uranyl nitrate solutions in about 2.5 M nitric acid generally constituted as the source phase. Uranyl transport appreciably increased with both stirring of the receiving phase and the carrier concentration in the organic membrane, while enhanced acidity of the strip side adversely affected the partioning of the cation into this phase. Among the several reagents tested, diluted ammonium carbonate (∼1M) solutions served efficiently as the stripant. Besides Accurel polypropylene (PP) film as the solid support for SLM, some silicon flat-sheet membranes with different inorganic fillers like silica, calcium silicate, calcium carbonate, chromium oxide, zinc oxide etc. and teflon membranes transported about 70% of uranium in nearly 7-8 hr employing 1 M ammonium carbonate as the strippant. Specifically, 30% TBP supported on Accurel flat-sheet supports transfered better than 70% of uranium from moderate acid feeds (2.5M) under similar conditions. Membranes supporting Aliquat-336, TLA, TOPO etc. yielded somewhat poor uranium recoveries. The feed : strip volume ratio showed an inverse relationship to the fraction of cation transported. (author). 9 refs., 2 tab s

  16. Photochemical reduction of uranyl ion by acetonitrile and propionitrile

    International Nuclear Information System (INIS)

    Brar, A.S.; Chander, R.; Sandhu, S.S.

    1979-01-01

    The photochemical reduction of uranyl ion by acetonitrile, propionitrile, benzonitrile, phenylacetonitrile, cyanoacetic acid and malononitrile in aqueous or aq. acetone medium using radiations >= 400 nm from a medium pressure mercury vapour lamp has been investigated. Except acetonitrile and propionitrile all other nitriles fail to bring about the reduction of uranyl ion. The reduction with aceto- and propionitriles has been found to obey pseudo-first order kinetics. The magnitude of rate of reduction with propionitrile is higher than that with acetonitrile. The pseudo-first order rate constants and quenching constant have been calculated from the kinetic data. It has been found that physical and chemical quenching compete with each other. The plot of reciprocal of quantum yield versus reciprocal (nitrile) is linear with a small intercept on the ordinate axis. Absorption spectra of uranyl ion in pure water, in the presence of acid and in the presence of acid+nitrile reveal that there is no ground state interaction between uranyl ion and the nitrile. A mechanism of photochemical reduction of uranyl ion based on α-hydrogen abstraction from the nitrile has been proposed. (auth.)

  17. Chemistry of the uranyl group. VI. Complexes of uranyl with hexamethylphosphoramide and urea

    Energy Technology Data Exchange (ETDEWEB)

    Zarli, B; Dall' olio, G; Sindellari, L [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi

    1976-01-01

    Some uranyl complexes with hexamethylphosphoramide (HMPA) and urea were prepared and characterized. The compounds with the former ligand have the general formula UO/sub 2/X/sub 2/.HMPA (where X = (C/sub 2/H/sub 5/)/sub 2/NCSe/sub 2//sup -/, (C/sub 2/H/sub 5/)/sub 2/NCS/sub 2//sup -/ or CH/sub 3/COO/sup -/). For the acetato derivatives a dimeric acetato-bridged structure is suggested. Some properties of UO/sub 2/(NO/sub 3/)/sub 2/.2(HMPA) are also described. With the latter ligand, in addition to the complexes UO/sub 2/(NO/sub 3/)/sub 2/.2urea and (UO/sub 2/(urea)/sub 4/(H/sub 2/0))(NO/sub 3/)/sub 2/ already known, the novel complexes UO/sub 2/(pycrate)/sub 2/.4urea and (UO/sub 2/(CH/sub 3/COO)/sub 2/.urea)sub(n) (where n is probably 2) have been prepared. All attempts to obtain urea complexes of uranyl diethyldithio- or diethyldiselenocarbamate failed and only adducts of unsatisfactory stoichiometry were isolated.

  18. Synthesizing A Phase Changing Bistable Electroactive Polymer And Silver Nanoparticles Coated Fabric As A Resistive Heating Element

    Science.gov (United States)

    Ren, Zhi

    Transducer technologies that convert energy from one form to another (e.g. electrical energy to mechanical energy or thermal energy and vise versa) are considered as the basic building blocks of robots and wearable electronics, two of the rapidly emerging technologies that impact our daily life. With an emphasis on developing the essential smart materials, this dissertation focuses on two specific transducer technologies, bistable large-strain electro-mechanical actuation and resistive Joule heating, in pursuit of refreshable Braille electronic displays and wearable thermal management element, respectively. Dielectric elastomers (DEs) have been intensively studied for their promising ability to mimic human muscles in providing efficient electro-mechanical actuation. They exhibit a unique combination of properties, including large strain, fast response, high energy density, mechanical compliancy, lightweight, and low cost. However, the softness of the DE materials, which is a prerequisite for electrically induced large actuation strain, has been hindering their application in adaptive structures. In these applications such as braille displays, a certain amount of mechanical support is necessary in addition to large strains for the device or system to function. Bistable electroactive polymers (BSEP) that leverage the electrically induced large-strain actuation of DE actuators and the bi-stable rigid-to-rigid deformation of shape memory polymers are innovated to provide large electrical actuation strain in their rubbery state and fix the deformation by cooling down to room temperature to incorporate mechanical rigidity. BSEP materials that can suppress electromechanical instability and exhibit stable mechanical properties in the rubbery state are desired. A bimodal BSEP material with a glass transition temperature right above room temperature has been synthesized employing simple UV curing process. The BSEP has a large storage modulus over 1GPa at room temperature

  19. Uranyl-organic assemblies with the macrocyclic ligand 1, 4, 8, 11-tetra-aza-cyclo-tetradecane-1, 4, 8, 11-tetraacetate (TETA)

    International Nuclear Information System (INIS)

    Thuery, Pierre

    2010-01-01

    Three uranyl ion complexes obtained from the reaction of uranyl nitrate hexahydrate and 1, 4, 8, 11-tetra-aza-cyclo-tetradecane-1, 4, 8, 11-tetraacetic acid (H 4 TETA) were characterized by their crystal structure. The centrosymmetric macrocycle, in the [3434] conformation with either carbon or nitrogen atoms as corners, is zwitterionic, with four carboxylate groups and two or four protonated nitrogen atoms. The complexes [(UO 2 ) 2 (H 2 TETA)(C 2 O 4 )(H 2 O) 2 ] (1) and [UO 2 (H 4 TETA)(H 2 O)].NO 3 .Cl (2) were synthesized under hydrothermal conditions and 1 includes additional oxalate ligands generated in situ. Both compounds are two-dimensional polymers in which the four-fold monodentate macrocyclic ligand unites either four uranyl oxalate dinuclear species (1) or isolated uranyl ions (2). Complex 3, [UO 2 (H 2 TETA)(H 2 O)].6H 2 O, was obtained at room temperature and, although it displays the same stoichiometry as 2, it differs from it by being a three-dimensional framework. Both 2 and 3 present channels containing either counter-ions or water molecules. As often observed, the water content of the low-temperature species, 3, is higher than that of the high-temperature one, 2. (author)

  20. Design and analysis of an energy-efficient O-QPSK coherent IR-UWB transceiver with a 0.52° RMS phase-noise fractional synthesizer

    Science.gov (United States)

    Ying, Yutong; Lin, Fujiang; Bai, Xuefei

    2018-03-01

    This paper explores an energy-efficient pulsed ultra-wideband (UWB) radio-frequency (RF) front-end chip fabricated in 0.18-μm CMOS technology, including a transmitter, receiver, and fractional synthesizer. The transmitter adopts a digital offset quadrature phase-shift keying (O-QPSK) modulator and passive direct-phase multiplexing technology, which are energy- and hardware-efficient, to enhance the data rate for a given spectrum. A passive mixer and a capacitor cross-coupled (CCC) source-follower driving amplifier (DA) are also designed for the transmitter to further reduce the low power consumption. For the receiver, a power-aware low-noise amplifier (LNA) and a quadrature mixer are applied. The LNA adopts a CCC boost common-gate amplifier as the input stage, and its current is reused for the second stage to save power. The mixer uses a shared amplification stage for the following passive IQ mixer. Phase noise suppression of the phase-locked loop (PLL) is achieved by utilizing an even-harmonics-nulled series-coupled quadrature oscillator (QVCO) and an in-band noise-aware charge pump (CP) design. The transceiver achieves a measured data rate of 0.8 Gbps with power consumption of 16 mW and 31.5 mW for the transmitter and the receiver, respectively. The optimized integrated phase noise of the PLL is 0.52° at 4.025 GHz. Project supported by the National Science and Technology Major Project of China (No. 2011ZX03004-002-01).

  1. A study of precipitation from pure solutions of uranyl nitrate

    International Nuclear Information System (INIS)

    Decrop, J.; Holder, J.; Sauteron, J.

    1961-01-01

    After its purification by extraction of the uranyl nitrate from the organic solvent, uranium has to be converted into solid form again: uranium trioxide (UO 3 ). It can be done either by thermal decomposition of uranyl nitrate or by precipitation of uranium, followed by filtration and calcination. Only the second method has been studied for now at the Bouchet plant. This paper reports the bench-scale and pilot-scale experiments of the studies of the precipitation of pure solutions of uranyl nitrate using ammonia (gaseous or in solution) or ammonium carbonate. These have been carried out at the Bouchet plant. It investigates the chemical aspect (pH, precipitates chemical composition) and the technical aspect of the different ways of precipitation (conditions of precipitation, decantation and filtration of precipitates). (M.P.)

  2. Uranyl Sulfate Nanotubules Templated by N-phenylglycine

    Directory of Open Access Journals (Sweden)

    Oleg I. Siidra

    2018-04-01

    Full Text Available The synthesis, structure, and infrared spectroscopy properties of the new organically templated uranyl sulfate Na(phgH+7[(UO26(SO410](H2O3.5 (1, obtained at room temperature by evaporation from aqueous solution, are reported. Its structure contains unique uranyl sulfate [(UO26(SO410]8− nanotubules templated by protonated N-phenylglycine (C6H5NH2CH2COOH+. Their internal diameter is 1.4 nm. Each of the nanotubules is built from uranyl sulfate rings sharing common SO4 tetrahedra. The template plays an important role in the formation of the complex structure of 1. The aromatic rings are stacked parallel to each other due to the effect of π–π interaction with their side chains extending into the gaps between the nanotubules.

  3. Study of water role during the complexing of uranyl aquanitrate compounds with cyclic polyethers

    International Nuclear Information System (INIS)

    Belomestnykh, V.I.; Sveshnikova, L.B.; Shabel'nik, K.S.

    1990-01-01

    By the method of vibrational spectroscopy and thermogravimetry the determining role of water molecules during complexing of uranyl aquonitrate compounds with macrocyclic polyethers is confirmed. It is ascertained that in the synthesized complexes of the composition UO 2 (NO 3 ) 2 (H 2 O) 2 ·mH 2 O·nL (m=0,1,2; L-18-crown-6, 15-crown-5, dibenzo-18-crown-6; n=1,2) molecules of macrocyclic ligand are joined at the expense of strong hydrogen bonds with participation of protons of crystallographically nonequivalent water molecules. In the compounds hydrogen bonds of water-water and water-nitrato group type are also realized. Energies of the above-mentioned bonds are calculated

  4. Electrochemical characterization of Uranyl-TODGA complex in a room temperature ionic liquid

    International Nuclear Information System (INIS)

    Sengupta, Arijit; Murali, M.S.; Mohapatra, P.K.

    2014-01-01

    Room temperature ionic liquids are new materials finding extensive use in many applications such as syntheses, catalysis, electrochemistry etc. including separation science. Some of them are known as green solvents set to be environment-friendly. With a view to apply the favourable properties of these neoteric solvents to separation science in nuclear related fields such as reprocessing and waste remediation, electrochemical characterization of the metal ions encountered in above fields e.g. U(VI), Pu(IV), Np(IV), Am(III) etc. their complexes with the ligands often becomes necessary and useful. In the present piece of work, electrochemical characterization has been carried out by cyclic voltammetry of uranyl complex with one of the most promising trivalent actinide extractants, namely, tetraoctyldiglycolamide (TODGA) dissolved/extracted into a room temperature ionic liquid, 1-methyl-3-octyl imidazolium bis(trifluoro methylsulphonyl) imide (C 8 mimNTf 2 )

  5. DNA conformational analysis in solution by uranyl mediated photocleavage

    DEFF Research Database (Denmark)

    Nielsen, Peter E.; Møllegaard, N E; Jeppesen, C

    1990-01-01

    Uranyl mediated photocleavage of double stranded DNA is proposed as a general probing for DNA helix conformation in terms of minor groove width/electronegative potential. Specifically, it is found that A/T-tracts known to constitute strong distamycin binding sites are preferentially photocleaved ......, uranyl photocleavage of the internal control region (ICR) of the 5S-RNA gene yields a cleavage modulation pattern fully compatible with that obtained by DNase I which also--in a more complex way--senses DNA minor groove width....

  6. Critical experiment study on uranyl nitrate solution experiment facility

    International Nuclear Information System (INIS)

    Zhu Qingfu; Shi Yongqian; Wang Jinrong

    2005-01-01

    The Uranyl Nitrate Solution Experiment Facility was constructed for the research on nuclear criticality safety. In this paper, the configuration of the facility is introduced; a series of critical experiments on uranyl nitrate solution is described later, which were performed for various uranium concentrations under different conditions, i.e. with or without neutron absorbers in the core and with or without water-reflector outside the core. Critical volume and the minimum 235U critical mass for different uranium concentrations are presented. Finally, theoretical analysis is made on the experimental results. (authors)

  7. Molecular approach of uranyl/mineral surfaces: theoretical approach

    International Nuclear Information System (INIS)

    Roques, J.

    2009-01-01

    As migration of radio-toxic elements through the geosphere is one of the processes which may affect the safety of a radioactive waste storage site, the author shows that numerical modelling is a support to experimental result exploitation, and allows the development of new interpretation and prediction codes. He shows that molecular modelling can be used to study processes of interaction between an actinide ion (notably a uranyl ion) and a mineral surface (a TiO 2 substrate). He also reports the predictive theoretical study of the interaction between an uranyl ion and a gibbsite substrate

  8. Uranyl peroxide enhanced nuclear fuel corrosion in seawater.

    Science.gov (United States)

    Armstrong, Christopher R; Nyman, May; Shvareva, Tatiana; Sigmon, Ginger E; Burns, Peter C; Navrotsky, Alexandra

    2012-02-07

    The Fukushima-Daiichi nuclear accident brought together compromised irradiated fuel and large amounts of seawater in a high radiation field. Based on newly acquired thermochemical data for a series of uranyl peroxide compounds containing charge-balancing alkali cations, here we show that nanoscale cage clusters containing as many as 60 uranyl ions, bonded through peroxide and hydroxide bridges, are likely to form in solution or as precipitates under such conditions. These species will enhance the corrosion of the damaged fuel and, being thermodynamically stable and kinetically persistent in the absence of peroxide, they can potentially transport uranium over long distances.

  9. Electronic structure and properties of uranyl compounds. Problems of electron-donor conception

    International Nuclear Information System (INIS)

    Glebov, V.A.

    1982-01-01

    Comparison of the series of the ligand mutual substitution in the uranyl compounds with the ligand series of d-elements and with the uranyl ''covalent model'', is made. The data on ionization potentials of the ligand higher valent levels and on the structure of some uranyl nitrate compounds are considered. It is concluded that the mechanism of the ligand effect on the properties of uranyl grouping is more complex, than it is supposed in the traditional representations on the nature of electron-donor interactions in the uranyl compounds

  10. Effect of metal-ion-to-fuel ratio on the phase formation of bioceramic phosphates synthesized by self-propagating combustion

    Directory of Open Access Journals (Sweden)

    Swamiappan Sasikumar and Rajagopalan Vijayaraghavan

    2008-01-01

    Full Text Available Synthetic calcium hydroxyapatite (HAP, Ca10 (PO46 (OH2 is a well-known bioceramic material used in orthopedic and dental applications because of its excellent biocompatibility and bone-bonding ability due to its structural and compositional similarity to human bone. Here we report, for the first time, the synthesis of HAP by combustion employing tartaric acid as a fuel. Calcium nitrate is used as the source of calcium and diammonium hydrogen phosphate serves as the source of phosphate ions. Reaction processing parameters such as the pH, fuel-oxidant ratio and autoignition temperature are controlled and monitored. The products were characterized by powder x-ray diffraction, which revealed the formation of a hexagonal hydroxyapatite phase. Fourier transform infrared spectroscopy (FT-IR spectra showed that the substitution of a carbonate ion occurs at the phosphate site. The morphology of the particles was imaged by scanning electron microscopy, which also revealed that the particles are of submicron size. Thermal analysis showed that the phase formation takes place at the time of combustion. Surface area and porosity analysis showed that the surface area is high and that the pores are of nanometer size. The mean grain size of the HAP powder, determined by the Debye–Scherrer formula, is in the range 20–30 nm. Chemical analyses to determine the Ca : P atomic ratio in synthesized ceramics were performed, and it was found to be 1 : 1.66.

  11. The interaction of uranyl ions with inorganic pyrophosphatase from baker's yeast

    International Nuclear Information System (INIS)

    Bienwald, B.; Heitmann, P.

    1978-01-01

    The interaction of uranyl ions with inorganic pyrophosphatase from baker's yeast was investigated by measurement of their effect on the protein fluorescence. Fluorescence titrations of the native enzyme with uranyl nitrate show that there is a specific binding of uranyl ions to the enzyme. It was deduced that each subunit of the enzyme binds one uranyl ion. The binding constant was estimated to be in the order of 10 7 M -1 . The enzyme which contains a small number of chemically modified carboxyl groups was not able to bind uranyl ions specifically. The modification of carboxyl groups was carried out by use of a water soluble carbodiimide and the nucleophilic reagent N-(2,4-dinitro-phenyl)-hexamethylenediamine. The substrate analogue calcium pyrophosphate displaced the uranyl ions from their binding sites at the enzyme From the results it is concluded that carboxyl groups of the active site are the ligands for the binding of uranyl ions. (author)

  12. Sorption of uranyl ions on hydrous silicon dioxide

    International Nuclear Information System (INIS)

    Lieser, K.H.; Quandt-Klenk, S.; Thybusch, B.

    1992-01-01

    Sorption of uranyl ions on SiO 2 .χH 2 O (silica gel) is investigated in absence and in presence of carbonate as function of pH. The curves obtained are very similar to those observed for sorption of uranyl ion on TiO 2 .χH 2 O, indicating the dominating influence of the uranium species in solution. Between pH 2 and 5 the sorption ratio R s increases with hydrolysis of uranyl ions (formation of UO 2 OH + ), around pH 7 it is nearly independent of pH, and at higher pH it decreases again. The equilibrium constants are calculated for these ranges. In presence of carbonate R s decreases drastically above pH 6, due to the formation of carbonato complexes in solution. Sorption of uranyl ions on SiO 2 .χH 2 O, on TiO 2 .χH 2 O, and on cryst. SiO 2 and Al 2 O 3 is compared. The problems of 'surface complexation' modelling are discussed. (orig.)

  13. Synthesis of pyrimidine carboxamide derivatives catalyzed by uranyl

    African Journals Online (AJOL)

    2014-09-02

    (Received September 2, 2014; revised January 1, 2016). ABSTRACT. An efficient and simple method was developed for the synthesis pyrimidine-5-carboxamides using. UO2(NO3)2.6H2O catalyst under conventional and microwave irradiation. The synthesis of dihydropyrimidine using uranyl nitrate had shown many ...

  14. Density functional study of uranyl (VI) amidoxime complexes

    International Nuclear Information System (INIS)

    Chi Fang-Ting; Xiong Jie; Hu Sheng; Xia Xiu-Long; Wang Xiao-Lin; Li Peng; Gao Tao

    2012-01-01

    Uranyl (VI) amidoxime complexes are investigated using relativistic density functional theory. The equilibrium structures, bond orders, and Mulliken populations of the complexes have been systematically investigated under a generalized gradient approximation (GGA). Comparison of (acet) uranyl amidoxime complexes ([UO 2 (AO) n ] 2−n , 1 ≤ n ≤ 4) with available experimental data shows an excellent agreement. In addition, the U−O(1), U−O(3), C(1)−N(2), and C(3)−N(4) bond lengths of [UO 2 (CH 3 AO) 4 ] 2− are longer than experimental data by about 0.088, 0.05, 0.1, and 0.056 Å. The angles of N(3)−O(3)−U, O(2)−N(1)−C(1), N(3)−C(3)−N(4), N(4)−C(3)−C(4), and C(4)−C(3)−N(3) are different from each other, which is due to existing interaction between oxygen in uranyl and hydrogen in amino group. This interaction is found to be intra-molecular hydrogen bond. Studies on the bond orders, Mulliken charges, and Mulliken populations demonstrate that uranyl oxo group functions as hydrogen-bond acceptors and H atoms in ligands act as hydrogen-bond donors forming hydrogen bonds within the complex

  15. Studying of the dehydration process of uranyl nitrate hexahydrate (Unh)

    International Nuclear Information System (INIS)

    Badalov, A.; Kamalov, J.J.; Homidov, B.J.; Mirsaidov, I.U.; Eshbekov, N.R.

    2005-01-01

    By the tensimeteric method is studying the dehydration process of uranyl nitrate hexahydrate (Unh). It is shown, that the temperature interval 300-400 K in equilibrium conditions the dehydration process of Unh runs in three stages. According to the equations of dependence of saturated steam pressure from temperature, the thermodynamic characteristics of each stage of the dehydration process of Unh are calculated

  16. Colorimetric peroxidase mimetic assay for uranyl detection in sea water

    KAUST Repository

    Zhang, Dingyuan

    2015-03-04

    Uranyl (UO2 2+) is a form of uranium in aqueous solution that represents the greatest risk to human health because of its bioavailability. Different sensing techniques have been used with very sensitive detection limits especially the recently reported uranyl-specific DNAzymes systems. However, to the best of our knowledge, few efficient detection methods have been reported for uranyl sensing in seawater. Herein, gold nanoclusters (AuNCs) are employed in an efficient spectroscopic method to detect uranyl ion (UO2 2+) with a detection limit of 1.86 ÎM. In the absence of UO2 2+, the BSA-stabilized AuNCs (BSA-AuNCs) showed an intrinsic peroxidase-like activity. In the presence of UO2 2+, this activity can be efficiently restrained. The preliminary quenching mechanism and selectivity of UO2 2+ was also investigated and compared with other ions. This design strategy could be useful in understanding the binding affinity of protein-stabilized AuNCs to UO2 2+ and consequently prompt the recycling of UO2 2+ from seawater.

  17. Multi-scale modelling of uranyl chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thanh-Nghi; Duvail, Magali, E-mail: magali.duvail@icsm.fr; Villard, Arnaud; Dufrêche, Jean-François, E-mail: jean-francois.dufreche@univ-montp2.fr [Institut de Chimie Séparative de Marcoule (ICSM), UMR 5257, CEA-CNRS-Université Montpellier 2-ENSCM, Site de Marcoule, Bâtiment 426, BP 17171, F-30207 Bagnols-sur-Cèze Cedex (France); Molina, John Jairo [Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-Nishihiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103 (Japan); Guilbaud, Philippe [CEA/DEN/DRCP/SMCS/LILA, Marcoule, F-30207 Bagnols-sur-Cèze Cedex (France)

    2015-01-14

    Classical molecular dynamics simulations with explicit polarization have been successfully used to determine the structural and thermodynamic properties of binary aqueous solutions of uranyl chloride (UO{sub 2}Cl{sub 2}). Concentrated aqueous solutions of uranyl chloride have been studied to determine the hydration properties and the ion-ion interactions. The bond distances and the coordination number of the hydrated uranyl are in good agreement with available experimental data. Two stable positions of chloride in the second hydration shell of uranyl have been identified. The UO{sub 2}{sup 2+}-Cl{sup −} association constants have also been calculated using a multi-scale approach. First, the ion-ion potential averaged over the solvent configurations at infinite dilution (McMillan-Mayer potential) was calculated to establish the dissociation/association processes of UO{sub 2}{sup 2+}-Cl{sup −} ion pairs in aqueous solution. Then, the association constant was calculated from this potential. The value we obtained for the association constant is in good agreement with the experimental result (K{sub UO{sub 2Cl{sup +}}} = 1.48 l mol{sup −1}), but the resulting activity coefficient appears to be too low at molar concentration.

  18. Structure and dynamics of aqueous solution of uranyl ions

    International Nuclear Information System (INIS)

    Chopra, Manish; Choudhury, Niharendu

    2014-01-01

    The present work describes a molecular dynamics simulation study of structure and dynamics of aqueous solution of uranyl ions in water. Structural properties of the system in terms of radial distribution functions and dynamical characteristics as obtained through velocity autocorrelation function and mean square displacements have been analyzed. The results for radial distribution functions show the oxygen of water to form the first solvation shell at 2.4 Å around the uranium atom, whereas the hydrogen atoms of water are distributed around the uranium atom with the major peak at around 3.0 Å. Analyses of transport behaviors of ions and water through MSD indicates that the diffusion of the uranyl ion is much less as compared to that of the water molecules. It is also observed that the dynamical behavior of water molecules gets modified due to the presence of uranyl ion. The effect of increase in concentration of uranyl ions on the structure and dynamics of water molecules is also studied

  19. Contribution to the study of the mechanism of extraction of uranyl chloride by long chain aliphatic amines; Contribution a l'etude du mecanisme d'extraction du chlorure d'uranyle par les amines aliphatiques a longues chaines

    Energy Technology Data Exchange (ETDEWEB)

    Rubinstein, G R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    After having studied and developed the mechanisms which may 'a priori' explain the extraction process (co-ordination, ion association or intermediate mechanism), experience shows that ion association only should be taken into consideration. The structure of the organic complex of uranyl chloride has been defined on the basis of the study of the variation of the distribution coefficient of uranium between the two phases at the equilibrium as a function of successively the activity of Cl{sup -} ions in the aqueous phase, the concentration of amine salt in the organic phase and finally of the concentration of uranium in the aqueous phase. The plotting of the results in bi-logarithmic co-ordinates enables us to propose the following formula for the extracted compound: UO{sub 2}Cl{sub 4}{sup --}(NR{sub 3}H{sup +}){sub 2}. The calculation of the equilibrium constant of formation of the organic compound of uranyl chloride has been possible in the case of diluted solutions of uranium only. (author) [French] Apres avoir expose et developpe les mecanismes qui a priori pouvaient expliquer le processus d'extraction (coordination, association d'ions ou mecanisme intermediaire), le recours a l'experience a finalement permis de ne retenir que l'association d'ions. La structure du complexe organique de chlorure d'uranyle a ete definie a partir de l'etude de la variation du coefficient de partage de l'uranium entre les deux phases a l'equilibre en fonction successivement de l'activite des ions Cl{sup -} en phase aqueuse, de la concentration de sel d'amine en phase organique et enfin de la concentration d'uranium de la phase aqueuse. La representation bilogarithmique des resultats de ces essais a permis de proposer la formule suivante pour le compose extrait: UO{sub 2}Cl{sub 4}{sup --}(NR{sub 3}H{sup +}){sub 2}. Le calcul de la constante d'equilibre de formation du compose organique de chlorure d'uranyle a ete seulement possible pour les solutions diluees en uranium. (auteur)

  20. New thermo-sensitive chelating surfactants for selective solvent-free extraction of uranyl nitrate

    International Nuclear Information System (INIS)

    Prevost, S.; Larpent, C.; Testard, F.; Coulombeau, H.; Baczko, K.; Berthon, L.; Desvaux, H.; Madic, C.; Zemb, T.

    2004-01-01

    Functional surfactants were synthesised by grafting a chelating group (amino-acid residue) to the tip of a poly-ethoxylated nonionic surfactant chain (C i E j : C i H 2i +1(OCH 2 CH 2 ) j OH)) or in a branched position. C i E j nonionic surfactants are known to be thermo-reversible and to exhibit a clouding phenomenon associated to phase separation of micelles. The functional surfactants retain both surface-active properties, characteristic thermo-reversible behaviour and have efficient complexing properties toward uranyl. In the presence of uranyl nitrate, small micelles are formed at ambient temperature and the de-mixing leads to a separation of the target ion trapped by the functional surfactant (cloud point extraction). Those surfactants are more efficient than mixture of classical C i E j and complexing agent solubilized in the micelles. This reveals a synergistic effect of the covalent bond between the chelating group and the nonionic surfactant C i E j . This paper presents a systematic study of the extraction and aggregation properties and the influence of the nature of the ions. (authors)

  1. PMR spectra and proton magnetic relaxation in uranyl nitrate-hexamethylenetetramine-urea-water gel forming system

    International Nuclear Information System (INIS)

    Vashman, A.A.; Pronin, I.S.; Brylkina, T.V.; Makarov, V.M.

    1979-01-01

    PMR spectra and proton relaxation in the nitrate-hexamethylenetetramine (HMTA)-urea-water gelling system are studied. According to PMR spectra products of HMTA chemical decomposition, which are supposed to be formed in the gelling process, have not been detected. Effect of hydrogen exchange upon PMR spectra of urea and water in the presence of HMTA and uranyl nitrate is studied. Periods of spin-lattice and spin-spin relaxations of water and HMTA protons in gels on the base of uranyl nitrate are found. Data on relaxation permitted to make qualitative conclusions upon the gel structure and HMTA molecule distribution over ''phases''. Nonproducibility of the results of period measurements in gels is the result of nonproducibility of the gel structure in the course of transformation of liquid solution into gel. Temperature dependences of proton relaxation in the gels are impossible yet to interpret on the basis of temperature behaviour of one correlation period, controlling dipole-dipole nuclear magnetic relaxation, and obeying Arrhenius dependence on the temperature

  2. Weathering of natural uranyl oxide hydrates: Schoepite polytypes and dehydration effects

    International Nuclear Information System (INIS)

    Finch, R.J.; Miller, M.L.; Ewing, R.C.

    1992-01-01

    Partial dehydration of schoepite, UO 3 x2H 2 O, is reported to produce three discrete schoepite polytypes with characteristic unit cell parameters, but this has not been confirmed. The loss of structural water from the schoepite interlayer results in progressive modification to the structure; expansion parallel to schoepite cleavage planes, and extensive fracturing. Dehydration of schoepite commences at grain boundaries and progresses inward until the entire grain is converted to dehydrated schoepite, UO 3 x0.8H 2 O. The volume decrease associated with dehydration results in expanded grain boundaries. These gaps can provide pathways for the access of groundwater, and uranyl silicates and uranyl carbonates have precipitated within these gaps, replacing both schoepite and dehydrated schoepite. Schoepite, however, is not observed to re-precipitate where in contact with dehydrated schoepite. Thus, while the formation of schoepite early during the corrosion of uraninite may be favored, schoepite is not a long-term solubility limiting phase for oxidized uranium in natural ground waters containing dissolved silica or carbonate. (orig.)

  3. Luminescent properties of [UO{sub 2}(TFA){sub 2}(DMSO){sub 3}], a promising material for sensing and monitoring the uranyl ion

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Ramos, Pablo; Silva, Manuela Ramos; Silva, Pedro S. Pereira da [Centro de Fisica da Universidade de Coimbra (CFisUC), Department of Physics, Universidade de Coimbra (Portugal); Costa, Ana L.; Melo, J. Sergio Seixas de [Centro de Quimica de Coimbra, Department of Chemistry, Universidade de Coimbra (Portugal); Pereira, Laura C.J. [Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, Universidade de Lisboa, Bobadela LRS (Portugal); Martin-Gil, Jesus, E-mail: pmr@unizar.es [Advanced Materials Laboratory, Escuela Tecnica Superior de Ingenierias Agrarias, University of Valladolid, Palencia (Spain)

    2016-03-15

    An uranyl complex [UO{sub 2}(TFA){sub 2}(DMSO){sub 3}] (TFA=deprotonated trifluoroacetic acid; DMSO=dimethyl sulfoxide) has been successfully synthesized by reacting UO{sub 2}(CH{sub 3}COO){sub 2} ·H{sub 2} O with one equivalent of (CF{sub 3} CO){sub 2} O and DMSO. The complex has been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis, FTIR spectroscopy, thermal analysis and absorption and emission spectroscopies. The spectroscopic properties of the material make it suitable for its application in the sensing and monitoring of uranyl in the PUREX process. (author)

  4. Antimicrobial activity of silica coated silicon nano-tubes (SCSNT) and silica coated silicon nano-particles (SCSNP) synthesized by gas phase condensation.

    Science.gov (United States)

    Tank, Chiti; Raman, Sujatha; Karan, Sujoy; Gosavi, Suresh; Lalla, Niranjan P; Sathe, Vasant; Berndt, Richard; Gade, W N; Bhoraskar, S V; Mathe, Vikas L

    2013-06-01

    Silica-coated, silicon nanotubes (SCSNTs) and silica-coated, silicon nanoparticles (SCSNPs) have been synthesized by catalyst-free single-step gas phase condensation using the arc plasma process. Transmission electron microscopy and scanning tunneling microscopy showed that SCSNTs exhibited a wall thickness of less than 1 nm, with an average diameter of 14 nm and a length of several 100 nm. Both nano-structures had a high specific surface area. The present study has demonstrated cheaper, resistance-free and effective antibacterial activity in silica-coated silicon nano-structures, each for two Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) was estimated, using the optical densitometric technique, and by determining colony-forming units. The MIC was found to range in the order of micrograms, which is comparable to the reported MIC of metal oxides for these bacteria. SCSNTs were found to be more effective in limiting the growth of multidrug-resistant Staphylococcus aureus over SCSNPs at 10 μg/ml (IC 50 = 100 μg/ml).

  5. IR spectra and structure of uranyl pivaloyltrifluoroacetylacetonate isolated in argon matrix

    International Nuclear Information System (INIS)

    Belyaeva, A.A.; Dushin, R.B.; Sidorenko, G.V.; Suglobov, D.N.

    1985-01-01

    When studying IR absorption spectra of a number of isotopomers of uranyl pivaloyl trifluoroacetonate (UPTFA), isolated in the matrix of argon and dissolved in benzene, and comparing them with the spectra of uranyl hexafluoroacetylacetonate (UHFA) vapours, it has been ascertained, that UPTFA vapours consist of monomers and dimers, and UPTFA solution in benzene - of dimers.It is shown, that the dimers have T-shaped structure, at that, the bond inside the dimer is realized by yl-atom of oxygen of an uranyl ion, included in the equatorial coordination sphere of another uranyl ion. Proofs of the dimer T-like structure distortion in gaseous or matrix-isolated state, as a result of which the difference of the angles between uranyl axes from 90 deg is observed, are given. In the framework of approximated model of isolated uranyl-ion the force constants for all the compounds investigated are calaculted

  6. Transuranium element incorporation into the β-U3O8 uranyl sheet

    International Nuclear Information System (INIS)

    Miller, M.L.; Burns, P.C.; Ewing, R.C.; Finch, R.J.

    1997-01-01

    Spent nuclear fuel (SNF) is unstable under oxidizing conditions. Although recent studies have determined the paragenetic sequence for uranium phases that result from the corrosion of SNF, there are only limited data on the potential of alteration phases for the incorporation of transuranium elements. The crystal chemical characteristics of transuranic elements (TUE) are to a certain extent similar to uranium; thus TUE incorporation into the sheets of uranyl oxide hydrate structures can be assessed by examination of the structural details of the β-U 3 O 8 sheet type. The sheets of uranyl polyhedra observed in the crystal structure of β-U 3 O 8 also occur in the mineral billietite, where they alternate with α-U 3 O 8 type sheets. Preliminary crystal structure determinations for the minerals ianthinite, and wyartite, indicate that these phases also contain β-U 3 O 8 type sheets. The β-U 3 O 8 sheet anion topology contains triangular, rhombic, and pentagonal sites in the proportions 2:1:2. In all structures containing β-U 3 O 8 type sheets, the triangular sites are vacant. The pentagonal sites are filled with U 6+ O 2 forming pentagonal bipyramids. The rhombic dipyramids filling the rhombic sites contain U 6+ O 2 in billietite, U 4+ O 2 in β-U 3 O 8 , U 4+ (H 2 O) 2 in ianthinite, and U 4+ O 3 in wyartite-II. Interlayer species include: H 2 O (billietite, wyartite II, and ianthinite), Ba 2+ (billietite) Ca 2+ wyartite II, and Co 3 2- wyartite II; there is no interlayer in β-U 3 O 8 . The similarity of known TUE coordination polyhedra with those of U suggests that the β-U 3 O 8 sheet will accommodate TUE substitution coupled with variations in apical anion configuration and interlayer population providing the required charge balance

  7. Selective Se-for-S substitution in Cs-bearing uranyl compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gurzhiy, Vladislav V., E-mail: vladgeo17@mail.ru [Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg, Russia Federation (Russian Federation); Tyumentseva, Olga S.; Krivovichev, Sergey V. [Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg, Russia Federation (Russian Federation); Tananaev, Ivan G. [Far Eastern Federal University, Suhanova st. 8, Vladivostok 690950 (Russian Federation)

    2017-04-15

    Phase formation in the mixed sulfate-selenate aqueous system of uranyl nitrate and cesium nitrate has been investigated. Two types of crystalline compounds have been obtained and characterized using a number of experimental (single crystal XRD, FTIR, SEM) and theoretical (information-based complexity calculations, topological analysis) techniques. No miscibility gaps have been observed for Cs{sub 2}[(UO{sub 2}){sub 2}(TO{sub 4}){sub 3}] (T= S, Se), which crystallizes in tetragonal system, P-42{sub 1}m, a =9.616(1)–9.856(2), c =8.105(1)–8.159(1) Å, V =749.6(2)–792.5(3) Å{sup 3}. Nine phases with variable amount of S and Se have been structurally characterized. The structures of the Cs{sub 2}[(UO{sub 2}){sub 2}(TO{sub 4}){sub 3}] (T= S, Se) compounds are based upon the [(UO{sub 2}){sub 2}(TO{sub 4}){sub 3}]{sup 2-} layers of corner-sharing uranyl pentagonal bipyramids and TO{sub 4} tetrahedra. The layers contain two types of tetrahedral sites: T1 (3-connected, i.e. having three O atoms shared by adjacent uranyl polyhedra) and T2 (4-connected). The Se-for-S substitution in tetrahedral sites is highly selective with smaller S{sup 6+} cation showing a strong preference for the more tightly bonded T2 site. Crystallization in the pure Se system starts with the formation of Cs{sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)](H{sub 2}O) crystals, its subsequent dissolution and formation of Cs{sub 2}[(UO{sub 2}){sub 2}(SeO{sub 4}){sub 3}]. The information-based structural complexity calculations for these two phases support the rule that more topologically complex structures form at the latest stages of crystallization. - Graphical abstract: Nine phases representing the Cs{sub 2}[(UO{sub 2}){sub 2}(TO{sub 4}){sub 3}] (T= S, Se) solid solution series with variable amount of S and Se have been prepared by isothermal evaporation from aqueous solutions and characterized using a number of experimental and theoretical techniques. No immiscibility is observed between the

  8. The state of uranyl ions in water-dioxane solvent mixtures

    International Nuclear Information System (INIS)

    Geipel, G.; Nebel, D.; Baraniak, L.

    1985-01-01

    A comparison of the spectra of uranyl ions in HCl and dioxane solutions leads to the conclusion that dioxane promotes complex formation. The investigation of spectra showed that taking into account the hydrolysis of uranyl ions in dioxane containing solutions, two successive equilibrium reactions take place. The formation constants were determined. Conductivity measurements confirmed the spectrophotometrically determined equilibria. In solutions containing up to 60 % dioxane there is no incorporation of dioxane in the solvating envelope of the uranyl ion. (author)

  9. Uranyl oxo activation and functionalization by metal cation coordination

    International Nuclear Information System (INIS)

    Arnold Polly, L.; Pecharman, A. F.; Hollis, E.; Parsons, S.; Love, J. B.; Yahia, A.; Maron, L.; Yahia, A.; Maron, L.

    2010-01-01

    The oxo groups in the uranyl ion [UO 2 ] 2+ - one of many oxo cations formed by metals from across the periodic table - are particularly inert, which explains the dominance of this ion in the laboratory and its persistence as an environmental contaminant. In contrast, transition metal oxo (M=O) compounds can be highly reactive and carry out difficult reactions such as the oxygenation of hydrocarbons. Here we show how the sequential addition of a lithium metal base to the uranyl ion constrained in a 'Pacman' environment results in lithium coordination to the U=O bonds and single-electron reduction. This reaction depends on the nature and stoichiometry of the lithium reagent and suggests that competing reduction and C-H bond activation reactions are occurring. (authors)

  10. Uranyl oxo activation and functionalization by metal cation coordination

    Energy Technology Data Exchange (ETDEWEB)

    Arnold Polly, L; Pecharman, A F; Hollis, E; Parsons, S; Love, J B [Univ Edinburgh, EaStCHEM Sch Chem, Edinburgh EH9 3JJ, Midlothian (United Kingdom); Yahia, A; Maron, L [Univ Toulouse 3, LPCNO, UMR 5215, INSA, CNRS, F-31077 Toulouse 4 (France); Yahia, A; Maron, L [Univ Montpellier 2, ENSCM, CNRS, ICSM, UMR 5257, CEA, Ctr Marcoule, F-30207 Bagnols Sur Ceze (France)

    2010-07-01

    The oxo groups in the uranyl ion [UO{sub 2}]{sup 2+} - one of many oxo cations formed by metals from across the periodic table - are particularly inert, which explains the dominance of this ion in the laboratory and its persistence as an environmental contaminant. In contrast, transition metal oxo (M=O) compounds can be highly reactive and carry out difficult reactions such as the oxygenation of hydrocarbons. Here we show how the sequential addition of a lithium metal base to the uranyl ion constrained in a 'Pacman' environment results in lithium coordination to the U=O bonds and single-electron reduction. This reaction depends on the nature and stoichiometry of the lithium reagent and suggests that competing reduction and C-H bond activation reactions are occurring. (authors)

  11. New chemistry of the uranyl ion in non aqueous media

    International Nuclear Information System (INIS)

    Siffredi, G.

    2008-12-01

    This work deals with new aspects of the chemistry of the uranyl(VI) ion {UO 2 } 2+ in anhydrous polar organic solvents such as the activation of the reputedly inert U-O yl bond and the controlled reduction of this species which represent a particularly active field of research that attracts much attention for both its fundamental aspects and applications. Treatment of uranyl(VI) compounds UO 2 X' 2 (X' = I, OTf, Cl) with Me 3 SiX (X = Cl, Br, I) reagents, in various anhydrous polar organic solvents, has been first considered. In most cases, reduction into tetravalent species with complete de-oxygenation of the uranyl {UO 2 } 2+ ion is observed. The reaction is particularly efficient in acetonitrile where the tetravalent [UX 4 (MeCN) 4 ] complexes, which are useful precursors in uranium chemistry, are isolated. In the course of these reactions, the influence of the solvent, the nature of X' and X in the UO 2 X' 2 precursor and the Me 3 SiX reagent are pointed out. Reaction of the uranyl(VI) UO 2 X 2 (X = I, Cl, OTf, NO 3 ) precursors with the anionic MC 5 R 5 (M = K, R = H, Me; M= Li, R = Me; M= Tl, R = H) reagents did not lead to the organometallic [(η 5 -C 5 R 5 ) n UO 2 X 2-n ] species (n = 1, 2) but to pentavalent uranyl(V) complexes. This method is a facile and rapid route towards the formation of stable pentavalent uranyl which offers promising sources for further U(V) chemical developments and for fundamental and applied interests. Their structure is strongly dependent on the nature of the solvent, the additional ligands X and of the M + cation. In pyridine, the {UO 2 (py) 5 } + ion appears to be an ubiquitous and a quite stable entity. The coordinating properties of the basic oxo groups, which coordinate easily to M + ions (M= Li, K, Tl), favour structural diversity with formation of hetero-polymetallic complexes such as [{UO 2 (py) 5 }{MX(py) 2 }] (M= Li, X I), [{UO 2 (py) 5 }{MX 2 (py) 2 }] ∞ (M= K, Tl, X= OTf; M= K, X= I), [{UO 2 (py) 5 }(M 2 X 3 )]

  12. Critical experiments on low enriched uranyl nitrate solution with STACY

    International Nuclear Information System (INIS)

    Miyoshi, Yoshinori

    1996-01-01

    As the STACY started steady operations, systematic criticality data on low enriched uranyl nitrate solution system could be accumulated. Main experimental parameters for the cylindrical tank of 60 cm in diameter were uranium concentration and the reflector condition. Basic data on a simple geometry will be helpful for the validation of the standard criticality safety codes, and for evaluating the safety margin included in the criticality designs. Experiments on the reactivity effects of structural materials such as borated concrete and polyethylene are on schedule next year as the second series of experiments using 10 wt% enriched uranyl solution. Furthermore, neutron interacting experiments with two slab tanks will be performed to investigate the fundamental properties of neutron interaction effects between core tanks. These data will be useful for making more reasonable calculation models and for evaluating the safety margin in the criticality designs for the multiple unit system. (J.P.N.)

  13. Uranyl(VI) luminescence spectroscopy at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Steudtner, Robin; Franzen, Carola; Brendler, Vinzenz [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Div. Surface Processes; Haubitz, Toni [Brandenburg Univ. of Technology, Cottbus-Senftenberg (Germany)

    2016-07-01

    We studied the influence of temperature and ionic strength on the luminescence characteristics (band position, decay time and intensity) of the free uranyl ion (UO{sub 2}{sup 2+}) in acidic aqueous solution. Under the chosen conditions an increasing temperature reduced both intensity and luminescence decay time of the UO{sub 2}{sup 2+} luminescence, but the individual U(VI) emission bands did not change.

  14. Tritium gettering from air with hydrogen uranyl phosphate

    International Nuclear Information System (INIS)

    Souers, P.C.; Uribe, F.S.; Stevens, C.G.; Tsugawa, R.T.

    1985-01-01

    Hydrogen uranyl phosphate (HUP), a solid proton electrolyte, getters tritium gas and water vapor from air by DC electrical action. We have reduced the formation of residual tritiated water to less than 2%, and demonstrated that HUP can clean a 5.5 m 3 working glove box. Data are presented to illustrate the parameters of the gettering and a model is derived. Two other tritium gettering electrolytes have been discovered. 9 refs., 5 figs., 3 tabs

  15. Tritium gettering from air with hydrogen uranyl phosphate. Revision 1

    International Nuclear Information System (INIS)

    Souers, P.C.; Uribe, F.S.; Stevens, C.G.; Tsugawa, R.T.

    1985-01-01

    Hydrogen uranyl phosphate (HUP), a solid proton electrolyte, getters tritium gas and water vapor from air by DC electrical action. We have reduced the formation of residual tritiated water to less than 2%, and demonstrated that HUP can clean a 5.5 m 3 working glove box. Data are presented to illustrate the parameters of the gettering and a model is derived. Two other tritium gettering electrolytes have been discovered. 9 refs., 5 figs., 3 tabs

  16. Structural determination of some uranyl compounds by vibrational spectroscopy

    International Nuclear Information System (INIS)

    Rodriguez S, A.; Martinez Q, E.

    1990-07-01

    The vibrational spectra of different uranyl compounds has been studied and of it spectral information has been used the fundamental asymmetric vibrational frequency, to determine the length and constant bond force U=O by means of the combination of the concept of absorbed energy and the mathematical expression of Badger modified by Jones. It is intended a factor that simplifies the mathematical treatment and the results are compared with the values obtained for other methods. (Author)

  17. Crystal structure of the uranyl-oxide mineral rameauite

    Czech Academy of Sciences Publication Activity Database

    Plášil, Jakub; Škoda, R.; Čejka, J.; Bourgoin, V.; Boulliard, J.C.

    2016-01-01

    Roč. 28, č. 5 (2016), s. 959-967 ISSN 0935-1221 R&D Projects: GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : rameauite * uranyl-oxide hydroxy-hydrate * crystal structure * Raman spectrum Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.362, year: 2016

  18. Development of the process for production of UO2 powder by atomization of uranyl nitrate

    International Nuclear Information System (INIS)

    Oliveira Lainetti, P.E. de.

    1991-01-01

    A method of direct conversion of uranyl nitrate hexahydrate (UNH) solution to ceramic grade uranium dioxide powders by thermal denitration in a furnace that combines atomization nozzle and a gas stirred bed is described. The main purpose of this work is to show that this alternative process is technically viable, specially if the recovery of the scrap generated in the nuclear fuel pellet production is required, without further generation of new liquid wastes. The steps for the development of the denitration unit as well as the characteristics of the final powders are described. Powder production experiments have been carried out for different atomization gas pressures and furnace upper section temperatures. Determination of impurity content, specific surface area, particle size and pore size distribution, density, U content, and O/U rate of uranium dioxide powders have been done; phase identification and morphology studies have also been performed. Sintered pellets have been studied by hydrostatic density determination and microstructure analyses. (author)

  19. Thermal and X-ray diffraction analysis studies during the decomposition of ammonium uranyl nitrate

    OpenAIRE

    Kim, B. H.; Lee, Y. B.; Prelas, M. A.; Ghosh, T. K.

    2012-01-01

    Two types of ammonium uranyl nitrate (NH4)2UO2(NO3)4?2H2O and NH4UO2(NO3)3, were thermally decomposed and reduced in a TG-DTA unit in nitrogen, air, and hydrogen atmospheres. Various intermediate phases produced by the thermal decomposition and reduction process were investigated by an X-ray diffraction analysis and a TG/DTA analysis. Both (NH4)2UO2(NO3)4?2H2O and NH4UO2(NO3)3 decomposed to amorphous UO3 regardless of the atmosphere used. The amorphous UO3 from (NH4)2UO2(NO3)4?2H2O was crysta...

  20. Preparation and thermogravimetric study of some uranyl phosphates

    International Nuclear Information System (INIS)

    Schaekers, J.M.

    1970-10-01

    The preparation of uranyl ammonium phosphate trihydrate (UAP = UO 2 NH 4 PO 4 .3H 2 O), acid uranyl phosphate tetrahydrate(AUP = UO 2 HPO 4 .4H 2 O) and neutral uranyl phosphate tetrahydrate (NUPT = (UO 2 ) 3 (PO 4 ) 2 .4H 2 O) was investigated during the data from the literature. The thermal decomposition in different atmospheres, such as air, oxygen, nitrogen and argon, was studied in the temperature range 25-1000 0 C. It was found that the pyrophosphate U 2 O 3 P 2 O 7 is a stable decomposition product of UAP as well as of AUP. A mixture of U 3 O 8 and U 2 O 3 P 2 O 7 is obtained when the NUPT is decomposed in an oxygen-free atmosphere. NUPT however is stable in an oxidising atmosphere. Hydrogen and carbon reductions were also carried out, and UO 2 or (UO) 2 P 2 O 7 as well as mixtures of these two products can be obtained, depending on the starting material and the reduction temperature. The different reduction and decomposition reactions were studied by means of thermogravimetric analysis, and activation energies were calculated where possible. I.R. spectral analysis was also used to identify various products with the same composition [af

  1. Safe use and waste disposal of uranyl acetate

    International Nuclear Information System (INIS)

    Sanchez, A.; Calvo, S.; Caparros, G.; Gallego, E.; Rascon, J.; Valladares, M.C.

    2006-01-01

    Radioactive labelled molecules are widely used in Biological Research Centres. The most common radioisotopes are: 32 P, 33 P, 35 S, 3 H, 14 C, 125 I and 45 Ca.Due to the inherent risk in the manipulation of these radiation unsealed sources, in these radioactive installations there are established radiological protection programs to reduce this potential risk and the professional exposure in the manipulation and in the radioactive waste generated. In these Biological Research Centres we used techniques with other radioactive products less used, that we must to control. It is the case of the use of uranyl acetate. Uranyl acetate is a uranium salt used in the preparation of samples for analysis in the electron microscope. Although the amounts used are relatively small, both the chemical and radiological toxicities of these compounds are significant and require working whit that some cautions, with the main emphasis on avoiding the possibility of inhalation of fine particulates or vapours. Due to changes in the Spanish regulations for this product, it was necessary to establish a specific control program in its manipulation. The purpose of this work is the accomplishment of specific protocols for the acquisition, manipulation, contamination measurements, inspections of the work zone and waste management, in order to minimize the risks in the manipulation of uranyl acetate,as well as apply the knowledge and use of specific norms for working with this product. (authors)

  2. Safe use and waste disposal of uranyl acetate

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, A.; Calvo, S.; Caparros, G.; Gallego, E.; Rascon, J.; Valladares, M.C. [Centro de Biologia Molecular, Madrid (Spain)

    2006-07-01

    Radioactive labelled molecules are widely used in Biological Research Centres. The most common radioisotopes are: {sup 32}P,{sup 33}P, {sup 35}S,{sup 3}H,{sup 14}C,{sup 125}I and {sup 45}Ca.Due to the inherent risk in the manipulation of these radiation unsealed sources, in these radioactive installations there are established radiological protection programs to reduce this potential risk and the professional exposure in the manipulation and in the radioactive waste generated. In these Biological Research Centres we used techniques with other radioactive products less used, that we must to control. It is the case of the use of uranyl acetate. Uranyl acetate is a uranium salt used in the preparation of samples for analysis in the electron microscope. Although the amounts used are relatively small, both the chemical and radiological toxicities of these compounds are significant and require working whit that some cautions, with the main emphasis on avoiding the possibility of inhalation of fine particulates or vapours. Due to changes in the Spanish regulations for this product, it was necessary to establish a specific control program in its manipulation. The purpose of this work is the accomplishment of specific protocols for the acquisition, manipulation, contamination measurements, inspections of the work zone and waste management, in order to minimize the risks in the manipulation of uranyl acetate,as well as apply the knowledge and use of specific norms for working with this product. (authors)

  3. Design of one evaporation system for uranyl nitrate solution

    International Nuclear Information System (INIS)

    Mancilla Romero, R.J.

    1975-01-01

    The authors propose an instant evaporation system with recirculation of the concentrated solution to raise the concentration from 50 to 1500 g of uranium per litre of solution. The capacity of the plant is to be 14.1 kg of uranium per hour. The main equipment used in the system is as follows: 1. Ring-type heat exchanger, for increasing the temperature of the mixture of fresh and recirculated solution from 80 to 115 0 C; 2. Separation tank, in which instant evaporation is carried out. The absolute pressure inside the tank will be 500 mmHg, with steam separation from a concentrated (78.5 wt.%) uranyl nitrate solution; 3. Desuperheater-condenser of horizontal tubular type for condensing water vapour and recovering any uranyl nitrate that may have been entrained; 4. Storage tank for the concentrate, with a capacity for one day's normal operation, and a heating coil to prevent crystallization of the concentrated solution; 5. Two storage tanks for feed and condensate with capacity for one day's normal operation; 6. Supporting structure for the above components. Virtually all equipment in contact with the uranyl nitrate solution will be made of 304 stainless steel. Saturated steam at 143.3 0 C will be required. The cost of the proposed system is $543 030.00. (author)

  4. Photochemistry and exciplex of the uranyl ion in aqueous solution

    International Nuclear Information System (INIS)

    Marcantonatos, M.D.

    1980-01-01

    The effects of acidity, temperature, self-quenching and H-donor concentration on the luminescent state of the aqua-uranyl(VI) ion have been studied in aqueous acidic nitrate and perchlorate solution. The detailed results cannot be explained by any single simple mechanism such as radiative, non-radiative or spontaneous collisional quenching, or irreversible hydrogen abstraction from water. Quantitative analysis of the results shows a far more complex mechanism, involving the adiabatic formation of the species *UO 2 H 2+ and *U 2 O 4 H 4+ , as already proposed by the author. This mechanism is supported by state and m.o. correlations. The abstraction of hydrogen from water is shown to take place by H atom transfer in a *uranyl-water complex intermediate, rather than by attack of H + on the fully occupied πsub(u) orbitals of uranium(V) in a well-defined uranyl water complex with strong charge transfer character. A qualitative description of the exciplex *U 2 O 4 H 4+ is shown to be possible in a v.b. formalism and the origin of its radiative properties is discussed on this basis. (author)

  5. Variable Denticity in Carboxylate Binding to the Uranyl Coordination Complexes

    International Nuclear Information System (INIS)

    Groenewold, G.S.; De Jong, Wibe A.; Oomens, Jos; Van Stipdonk, Michael J.

    2010-01-01

    Tris-carboxylate complexes of the uranyl (UO2)2+ cation with acetate and benzoate were generated using electrospray ionization mass spectrometry, and then isolated in a Fourier transformion cyclotron resonance mass spectrometer. Wavelength-selective infrared multiple photon dissociation (IRMPD) of the tris-acetatouranyl anion resulted in a redox elimination of an acetate radical, which was used to generate an IR spectrum that consisted of six prominent absorption bands. These were interpreted with the aid of density functional theory calculations in terms of symmetric and antisymmetric -CO2 stretches of both the monodentate and bidentate acetate, CH3 bending and umbrella vibrations, and a uranyl O-U-O asymmetric stretch. The comparison of the calculated and measured IR spectra indicated that the tris-acetate complex contained two acetate ligands bound in a bidentate fashion, while the third acetate was monodentate. In similar fashion, the tris-benzoate uranyl anion was formed and photodissociated by loss of a benzoate radical, enabling measurement of the infrared spectrum that was in close agreement with that calculated for a structure containing one monodentate, and two bidentate benzoate ligands.

  6. The study of kinetics of uranyl nitrate extraction and reextraction, di-n-butylphosphoric acid reextraction in the flow mixer in the system aqueous solutions - tri-n-butyl phosphate in diluent

    International Nuclear Information System (INIS)

    Shchepetil'nikov, N.N.; Timofeev, A.N.; Kharitonov, V.V.

    1992-01-01

    Kinetics of uranyl nitrate and HNO 3 extraction and reextraction in a flow-type mixer for the system 30 vol.% TBP in extractant dearomatized diluent (EDD) was studied. Kinetics of dibutylphosphate acid reextraction was considered and the influence of uranium and zirconium presence on the process was investigated. It is shown that in laboratory mixer of continuous action in case of phase contact duration of 1 min. in system 30 % solution of TBP in EDD extraction sufficiently similar to equilibrium extraction of uranyl nitrate and nitric acid during their extraction and reextraction is achieved

  7. A series of sheet-structured alkali metal uranyl oxalate hydrates: structures and IR spectra

    International Nuclear Information System (INIS)

    Giesting, P.A.; Porter, N.J.; Burns, P.C.

    2006-01-01

    The novel compounds K[(UO 2 ) 2 (C 2 O 4 ) 2 OH] . 2 H 2 O (KUrO x ), Rb[(UO 2 ) 2 (C 2 O 4 ) 2 OH] . 2 H 2 O (RbUrO x ), and Cs[(UO 2 ) 2 (C 2 O 4 ) 2 OH] . H 2 O (CsUrO x ) have been synthesized by mild hydrothermal methods. Single crystal diffraction data collected at 125 K using MoK α radiation and a CCD-based area detector were used to solve and refine the crystal structures by full-matrix least-squares techniques to agreement indices (KUrO x , RbUrO x , CsUrO x ) wR 2 = 0.045, 0.062, 0.042 for all data, and R1 = 0.023, 0.030, 0.022 calculated for 1834, 1863, 1821 unique reflections respectively. The compounds KUrO x , RbUrO x , and CsUrO x are all monoclinic, space group P2 1 /m, Z = 2. The unit cell of KUrO x has the dimensions a = 5.6427(4), b = 13.7123(9), c = 9.2669(6) Aa, β = 98.7490(10) , V = 708.68(8) Aa 3 . The unit cell of RbUrO x has the dimensions a = 5.6225(4), b = 13.8339(9), c = 9.3308(6) Aa, β = 98.1590(10) , V = 718.41(8) Aa 3 . The unit cell of CsUrO x has the dimensions a = 5.4688(3), b = 13.5710(8), c = 9.5408(5) Aa, β = 97.5830(10) , V = 701.90(7) Aa 3 . The structures consist of chains of uranyl pentagonal bipyramids connected by oxalate groups and hydroxyl groups, and are isotypic with the compound NR 4 [(UO 2 ) 2 (C 2 O 4 ) 2 OH] . 2 H 2 O studied by Artem'eva et al. (2003); all four of these compounds are structurally composed of sheets made by polymerizing the chains of UO 2 C 2 O 4 (H 2 O) . 2 H 2 O (Jayadevan and Chackraburtty, 1972; Mikhailov et al., (1999)), this being achieved by removing a H atom from an H 2 O group in the coordination sphere of the uranyl ion to form a hydroxyl vertex that is shared by two uranyl ions. Compensating positive charges are provided by the inclusion of large monovalent cations in channels that run through the sheets; these channels also contain hydrogen-bound H 2 O groups. The positions of the cations and H 2 O groups change in relation to the uranyl oxalate sheets and to each other through the

  8. A family of uranyl-aromatic dicarboxylate (pht-, ipa-, tpa-) framework hybrid materials: photoluminescence, surface photovoltage and dye adsorption.

    Science.gov (United States)

    Gao, Xue; Wang, Che; Shi, Zhong-Feng; Song, Jian; Bai, Feng-Ying; Wang, Ji-Xiao; Xing, Yong-Heng

    2015-07-07

    Four uranyl complexes [(UO2)(pht)H2O]·H2O (pht = phthalic acid) (1), (UO2)2(Hipa)4(H2O)2 (Hipa = isophthalic acid) (2), (UO2)(tpa)(DMF)2 (tpa = terephthalic acid) (3) and (UO2)(box)2 (box = benzoic acid) (4) were synthesized by the reaction of UO2(CH3COO)2·2H2O as the metal source and phthalic acid, isophthalic acid, terephthalic acid or benzoic acid as the ligand. They were characterized by elemental analyses, IR, UV-Vis, XRD, single crystal X-ray diffraction analysis and thermal gravimetric analysis. The structural analysis reveals that complex 1 exhibits a one-dimensional chain structure constructed by the building unit [(UO2)2(pht)4(H2O)2] and further extends the chain into a 2D supramolecular architecture by hydrogen bonding interactions. Complex 2 is a discrete [(UO2)2(Hipa)4(H2O)2] structure, and by the hydrogen bonding interaction, forms a 3D supramolecular structure. In complexes 3 and 4, adjacent uranyl polyhedra form a 1D chain through bridging terephthalic acid and benzoic acid, respectively. In order to extend their functional properties, their photoluminescence, surface photovoltage and dye adsorption properties have been studied.

  9. Functional polyterthiophene-appended uranyl-salophen complex: electropolymerization and ion-selective response for monohydrogen phosphate.

    Science.gov (United States)

    Kim, Junghwan; Kang, Dong Min; Shin, Sung Chul; Choi, Myong Yong; Kim, Jineun; Lee, Shim Sung; Kim, Jae Sang

    2008-04-28

    We have synthesized a bis(terthiophene)-appended uranyl-salophen complex, comprising N,N'-bis[4-(5,2':5',2''-terthiophen-3'-yl)salicylidene]-1,2-ethanediamine-uranyl complexes (TUS), and used it as a monomer for the electrochemical polymerizations (poly-TUS) on glassy carbon surfaces to prepare functionalized conducting polymer (CP) films. The poly-TUS films prepared from propylene carbonate/0.1 M tetrabutyl ammonium perchlorate (TBAP) on a glassy carbon electrode have both the functionality of ion-to-electron transducers (solid contact) and Lewis-acidic binding sites for a monohydrogen phosphate (MHP) ion-selective electrode (ISE). The CP/poly-TUS sensor showed a linear range between 1.0 x 10(-1) and 1.0 x 10(-4.5) M with a near-Nernstian behavior (-30.4 mV decade(-1)) at a pH of 8.2. The detection limit of the electrode was 10(-5.0) M and the response time was improved (polyvinyl chloride (PVC) liquid membrane with or without tridodecylmethylammonium chloride (TDMACl) as an additive was also constructed and its performance as an MHP-ISE were studied. The superior selectivity and sensitivity of the CP/poly-TUS sensor enabled the direct measurement of MHP in a wide variety of applications.

  10. Uranyl ion sorption mechanisms on titanium oxide: a multi-scale approach

    International Nuclear Information System (INIS)

    Vandenborre, J.; Drot, R.; Simoni, E.; Dong, W.; Du, J.; Dossot, M.; Humbert, B.; Ehrhardt, J.J.

    2005-01-01

    Full text of publication follows: Radionuclides retention mechanisms onto mineral phases is of primary importance for nuclear waste management. The aim of the presented study is to demonstrate that it is possible to predict the retention properties of a methodological powdery substrate from the study of its natural crystallographic orientations. Among the radionuclides of interest, U(VI) can be seen as a model of the radionuclides oxo-cations. The substrate under study is the titanium oxide (TiO 2 ). In fact, rutile can be found as powder and also as manufactured single crystal which allows to study the retention processes on perfectly known crystallographic planes. Since the repartition of the different crystallographic orientations are known for the powder, the results obtained for the single crystals can directly be used to account for the powder retention properties. By using combined spectroscopic techniques such as TRLFS, XPS, DRIFT and SHG, it is possible to determine the nature of the reactive surface sites and also the surface species. XPS and TRLFS measurements allowed to determine that two same uranyl surface species were formed on titania (110) and (001). Only, the relative intensities of these species vary with the surface coverage. Atomic Force Microscopy was carried out to verify that no surface precipitation occurs for the higher surface coverages. Moreover, these analysis have also evidenced that the U(VI) sorption is homogeneous. These observations were corroborated by SHG experiments (mainly for (001)) which have also shown that the sorption occurs, in a first step, onto preferential surface symmetry axis. For rutile powder, the preferential crystallographic orientations are (110), (100) and (101) in the ratio 60/20/20. TRLFS and XPS experiments have shown that two uranyl surface species are formed whatever the pH value ranged from 1 to 5. The spectroscopic characteristics of these species are the same as the ones observed on (110) and (001

  11. Synthesis and complexation properties towards uranyl cation of carboxylic acid derivatives of p-tert-butyl-calix[6]arene

    International Nuclear Information System (INIS)

    Souane, R.

    2005-03-01

    In the fuel reprocessing plants radioactive metals, and more particularly, uranium in UO 2 2+ form in the various installations, have many varied physico-chemical forms and there is a risk of exposure and internal contamination in the nuclear industry. It is necessary to exert a medical control to ensure the protection of the health of the workers. This medical control is done by dosing uranyl cation in the urine of the exposed people. This work forms part of this context. Indeed, we prepared a ligand able to complex the ion uranyl and which is also to be grafted on a solid support. In the family of calixarenes, the calix[6]arenes functionalized by three or four carboxylic functions were selected like chelating molecules of the ion uranyl. The properties of complexation of these calixarenes were studied by potentiometry in methanol, under these conditions balances of protonation and complexation were determined and the constant partners were obtained using the Hyperquad program. We synthesized tri-carboxylic calix[6]arenes comprising of the groupings nitro (NO 2 ) in para position of phenol in order to see the influence of a substitution in para position on the complexation. We also synthesized calix[6]arenes tetra-carboxylic in order to show the role of an additional carboxylic acid grouping. The potentiometric study determined thermodynamic parameters of protonation and complexation of carboxylic calix[6]arenes. The results of the complexation highlighted which complex UO 2 L corresponding to the ligand para-tert-butyl-calix[6]arene tetra-acid is more stable than that corresponding to the ligand mono-nitro calix[6]arene tri-acid (ΔlogΒ110 = 4.3), and than the effect of the groupings nitro in para position has low influence on the complexation of UO 2 2+ . This makes it possible to consider as possible the grafting of the calix[6]arenes which one knows the behaviour of trapping. To this end we synthesized the ligand 23. (author)

  12. Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures

    International Nuclear Information System (INIS)

    Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

    2012-01-01

    Highlights: ► The stability of peroxide in uranyl peroxo carbonato complex solutions with different temperatures was characterized. ► The decomposition rate of uranyl peroxo carbonato complex ion to uranyl tris-carbonato complex ion was observed to increase with temperature ► The decomposition kinetics of uranyl peroxo carbonato complex ions was evaluated by absorption and Raman spectroscopies. ► A precipitate of uranyl peroxo carbonato complex solution was evaluated with XRD. - Abstract: This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144 × 10 3 J mol −1 . The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature.

  13. Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kwang-Wook, E-mail: nkwkim@kaeri.re.kr [Korea Atomic Energy Research Institute, 1045 Daedeok daero, Yuseong, Daejeon 305-353 (Korea, Republic of); Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon [Korea Atomic Energy Research Institute, 1045 Daedeok daero, Yuseong, Daejeon 305-353 (Korea, Republic of); Shin, Dong-Woo [Gyeongsang National University, 900 Gajwa, Jinju 660-701 (Korea, Republic of)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer The stability of peroxide in uranyl peroxo carbonato complex solutions with different temperatures was characterized. Black-Right-Pointing-Pointer The decomposition rate of uranyl peroxo carbonato complex ion to uranyl tris-carbonato complex ion was observed to increase with temperature Black-Right-Pointing-Pointer The decomposition kinetics of uranyl peroxo carbonato complex ions was evaluated by absorption and Raman spectroscopies. Black-Right-Pointing-Pointer A precipitate of uranyl peroxo carbonato complex solution was evaluated with XRD. - Abstract: This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144 Multiplication-Sign 10{sup 3} J mol{sup -1}. The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature.

  14. Effect of lead salts on phase, morphologies and photoluminescence of nanocrystalline PbMoO4 and PbWO4 synthesized by microwave radiation

    Directory of Open Access Journals (Sweden)

    Phuruangrat Anukorn

    2016-09-01

    Full Text Available PbMoO4 and PbWO4 were successfully synthesized by microwave radiation using different lead salts (acetate, chloride, nitrate and sulfate and Na2MO4 (M = Mo, W in propylene glycol. The products were characterized by X-ray diffraction (XRD, scanning and transmission electron microscopy (SEM, TEM, Fourier transform infrared (FT-IR, Raman spectroscopy and photoluminescence (PL spectroscopy. In this research, morphologies, crystallization and photoluminescence of the products were influenced by the kinetics of anions, including the detection of M–O (M = Mo, W stretching modes in the (MO42− tetrahedrons. Photoluminescence of PbMoO4 synthesized from Pb(NO32 and of PbWO4 synthesized from PbCl2 showed the strongest blue emission due to the electronic diffusion in tetrahedrons at room temperature.

  15. Energy transfer and quenching processes of excited uranyl ion and lanthanide ions in solutions

    International Nuclear Information System (INIS)

    Yamamura, Tomoo; Tomiyasu, Hiroshi

    1995-01-01

    Deactivation processes of photoexcited uranyl ion by various lanthanide ions in aqueous solution were studied. Each lanthanide ions show different interaction with excited uranyl ion depending on its lowest excited energy level, the number of 4f electrons and the acid concentration of the solution. (author)

  16. A surface structural model for ferrihydrite II: Adsorption of uranyl and carbonate

    NARCIS (Netherlands)

    Hiemstra, T.; Riemsdijk, van W.H.; Rossberg, A.; Ulrich, K.

    2009-01-01

    The adsorption of uranyl (UO22+) on ferrihydrite has been evaluated with the charge distribution (CD) model for systems covering a very large range of conditions, i.e. pH, ionic strength, CO2 pressure, U(VI) concentration, and loading. Modeling suggests that uranyl forms bidentate inner sphere

  17. A protein engineered to bind uranyl selectively and with femtomolar affinity

    Science.gov (United States)

    Zhou, Lu; Bosscher, Mike; Zhang, Changsheng; Özçubukçu, Salih; Zhang, Liang; Zhang, Wen; Li, Charles J.; Liu, Jianzhao; Jensen, Mark P.; Lai, Luhua; He, Chuan

    2014-03-01

    Uranyl (UO22+), the predominant aerobic form of uranium, is present in the ocean at a concentration of ~3.2 parts per 109 (13.7 nM) however, the successful enrichment of uranyl from this vast resource has been limited by the high concentrations of metal ions of similar size and charge, which makes it difficult to design a binding motif that is selective for uranyl. Here we report the design and rational development of a uranyl-binding protein using a computational screening process in the initial search for potential uranyl-binding sites. The engineered protein is thermally stable and offers very high affinity and selectivity for uranyl with a Kd of 7.4 femtomolar (fM) and >10,000-fold selectivity over other metal ions. We also demonstrated that the uranyl-binding protein can repeatedly sequester 30-60% of the uranyl in synthetic sea water. The chemical strategy employed here may be applied to engineer other selective metal-binding proteins for biotechnology and remediation applications.

  18. Production and Characterization of Desmalonichrome Relative Binding Affinity for Uranyl Ions in Relation to Other Siderophores

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Kai-For; Dai, Ziyu; Wunschel, David S.

    2016-06-24

    Siderophores are Fe binding secondary metabolites that have been investigated for their uranium binding properties. Much of the previous work has focused on characterizing hydroxamate types of siderophores, such as desferrioxamine B, for their uranyl binding affinity. Carboxylate forms of these metabolites hold potential to be more efficient chelators of uranyl, yet they have not been widely studied and are more difficult to obtain. Desmalonichrome is a carboxylate siderophore which is not commercially available and so was obtained from the ascomycete fungus Fusarium oxysporum cultivated under Fe depleted conditions. The relative affinity for uranyl binding of desmalonichrome was investigated using a competitive analysis of binding affinities between uranyl acetate and different concentrations of iron(III) chloride using electrospray ionization mass spectrometry (ESI-MS). In addition to desmalonichrome, three other siderophores, including two hydroxamates (desferrioxamine B and desferrichrome) and one carboxylate (desferrichrome A) were studied to understand their relative affinities for the uranyl ion at two pH values. The binding affinities of hydroxymate siderophores to uranyl ion were found to decrease to a greater degree at lower pH as the concentration of Fe (III) ion increases. On the other hand, lowering pH has little impact on the binding affinities between carboxylate siderophores and uranyl ion. Desmalonichrome was shown to have the greatest relative affinity for uranyl at any pH and Fe(III) concentration. These results suggest that acidic functional groups in the ligands are critical for strong chelation with uranium at lower pH.

  19. Widely tunable THz synthesizer

    Science.gov (United States)

    Hindle, F.; Mouret, G.; Eliet, S.; Guinet, M.; Cuisset, A.; Bocquet, R.; Yasui, T.; Rovera, D.

    2011-09-01

    The generation of cw-THz radiation by photomixing is particularly suited to the high resolution spectroscopy of gases; nevertheless, until recently, it has suffered from a lack of frequency metrology. Frequency combs are a powerful tool that can transfer microwave frequency standards to optical frequencies and a single comb has permitted accurate (10-8) THz frequency synthesis with a limited tuning range. A THz synthesizer composed of three extended cavity laser diodes phase locked to a frequency comb has been constructed and its utility for high resolution gas phase spectroscopy demonstrated. The third laser diode allows a larger tuning range of up to 300 MHz to be achieved without the need for large frequency excursions, while the frequency comb provides a versatile link to be established from any traceable microwave frequency standard. The use of a single frequency comb as a reference for all of the cw-lasers eliminates the dependency of synthesized frequency on the carrier envelope offset frequency. This greatly simplifies the frequency comb stabilization requirements and leads to a reduced instrument complexity.

  20. Structural investigation of the complexation of uranyl and lanthanide ions by CMPO-functionalized calixarenes

    International Nuclear Information System (INIS)

    Cherfa, S.

    1998-12-01

    A way to reduce the volume of nuclear wastes is to make a simultaneous extraction of actinides and lanthanides for their ulterior separation. Historically, the two first series of extractants used for the reprocessing of these wastes are the phosphine oxides and the CMPO (carbamoyl methyl phosphine oxide). In order to better know the type of complexes formed during the extraction, have been carried out structural studies concerning these two series (uranyl complexes and lanthanide nitrates). These studies have been carried out by X-ray diffraction on monocrystals. More recently, a new series of extracting molecules of lanthanides (III) and actinides (III) have been developed. It has been shown that in functionalizing an organic macrocycle of calixarene type (cyclic oligomer resulting of the poly-condensation of phenolic units) by a ligand of CMPO type, the extracting power of these molecules in terms of yield and selectivity towards the lighter lanthanides was superior to those of the CMPO alone. This study, carried out by X-ray diffraction on monocrystals of complexes formed between these ligands calix[4]arenes-CMPO (with 4 phenolic units) with uranyl and lanthanides nitrates, has allowed to define the type of the formed complexes, that is to say to establish the stoichiometry and the coordination mode (monodentate or bidentate) of the CMPO functions. These different steps of characterization have allowed too to determine the correlations existing between the complexes structures in the one hand and the selectivity and the exacerbation of the extracting power measured in liquid phase on the other hand. (O.M.)

  1. Quantification of uranyl in presence of citric acid; Cuantificacion de uranilo en presencia de acido citrico

    Energy Technology Data Exchange (ETDEWEB)

    Garcia G, N.; Barrera D, C.E. [UAEM, Facultad de Quimica, 50000 Toluca, Estado de Mexico (Mexico); Ordonez R, E. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: nidgg@yahoo.com.mx

    2007-07-01

    To determine the influence that has the organic matter of the soil on the uranyl sorption on some solids is necessary to have a detection technique and quantification of uranyl that it is reliable and sufficiently quick in the obtaining of results. For that in this work, it intends to carry out the uranyl quantification in presence of citric acid modifying the Fluorescence induced by UV-Vis radiation technique. Since the uranyl ion is very sensitive to the medium that contains it, (speciation, pH, ionic forces, etc.) it was necessary to develop an analysis technique that stands out the fluorescence of uranyl ion avoiding the out one that produce the organic acids. (Author)

  2. Comparative study of uranyl(VI) and -(V) carbonato complexes in an aqueous solution.

    Science.gov (United States)

    Ikeda, Atsushi; Hennig, Christoph; Tsushima, Satoru; Takao, Koichiro; Ikeda, Yasuhisa; Scheinost, Andreas C; Bernhard, Gert

    2007-05-14

    Electrochemical, complexation, and electronic properties of uranyl(VI) and -(V) carbonato complexes in an aqueous Na2CO3 solution have been investigated to define the appropriate conditions for preparing pure uranyl(V) samples and to understand the difference in coordination character between UO22+ and UO2+. Cyclic voltammetry using three different working electrodes of platinum, gold, and glassy carbon has suggested that the electrochemical reaction of uranyl(VI) carbonate species proceeds quasi-reversibly. Electrolysis of UO22+ has been performed in Na2CO3 solutions of more than 0.8 M with a limited pH range of 11.7 < pH < 12.0 using a platinum mesh electrode. It produces a high purity of the uranyl(V) carbonate solution, which has been confirmed to be stable for at least 2 weeks in a sealed glass cuvette. Extended X-ray absorption fine structure (EXAFS) measurements revealed the structural arrangement of uranyl(VI) and -(V) tricarbonato complexes, [UO2(CO3)3]n- [n = 4 for uranyl(VI), 5 for uranyl(V)]. The bond distances of U-Oax, U-Oeq, U-C, and U-Odist are determined to be 1.81, 2.44, 2.92, and 4.17 A for the uranyl(VI) complex and 1.91, 2.50, 2.93, and 4.23 A for the uranyl(V) complex, respectively. The validity of the structural parameters obtained from EXAFS has been supported by quantum chemical calculations for the uranyl(VI) complex. The uranium LI- and LIII-edge X-ray absorption near-edge structure spectra have been interpreted in terms of electron transitions and multiple-scattering features.

  3. Comparing uranyl sorption complexes on soil and reference clays

    International Nuclear Information System (INIS)

    Chisholm-Brause, C.J.; Berg, J.M.; Conradson, S.D.; Morris, D.E.; McKinley, J.P.; Zachara, J.M.

    1993-01-01

    Clay minerals and other components in natural soils may play a key role in limiting the mobility of uranium in the environment through the formation of sorption complexes. Reference clays are frequently used as models to study sorption processes because they have well-known chemical and physical properties, but they may differ chemically and morphologically from clays derived from natural soils. Therefore, inferences based on reference clay data have been questioned. The authors have used luminescence and x-ray absorption spectroscopies to characterize the sorption complexes of aqueous uranyl (UO 2 2+ ) species on two soil smectites from the Kenoma and Ringold formations, and compared these results to those obtained on reference smectite clays. The pH dependence of uptake suggests that the ratio of sorption on amphoteric edge sites is greater for the soil smectites than for reference clays such as Wyoming montmorillonite (SWy-1). The luminescence spectra for uranyl sorbed to the soil clays are very similar to those for uranyl sorbed principally to the edge sites of SWy-1. This observation supports the solution data suggesting that adsorption to amphoteric sites is a more important mechanism for soil clays. However, the spectral data indicate that the sorption complexes on natural and reference clays are quite similar. Furthermore, as with the reference clays, the authors have found that the chemistry of the solution plays a greater role in defining the sorption complex than does the clay matrix. Thus, if differences in surface properties are adequately taken into account, the reference clays may serve as useful analogs for soil clays in investigations of metal-ion sorption

  4. Determination of free nitric acid in uranyl nitrate solution

    International Nuclear Information System (INIS)

    Mayankutty, P.C.; Ravi, S.; Nadkarni, M.N.

    1981-01-01

    Potentiometric titration of uranyl nitrate solution with sodium hydroxide exhibits two peaks. The first peak characterises the following reaction, UO 2 (C 2 O 4 )+NaOH Na[UO 2 (C 2 O 4 )(OH)]. This reaction, indicating the partial hydrolysis of uranyl oxalate complex, appears to be complete at pH9. If the titration is carried out to this end-point pH, the total alkali consumed can be equated to the sum of uranium content and the free acidity present in the sample volume. Based on this, a method was standardised to determine the free acidity in uranyl nitrate solution. The sample, taken in a solution of potassium oxalate previously adjusted to pH9, is titrated to this pH with standard sodium hydroxide. The free acidity in the sample can be computed by subtracting the alkali reacted with uranium from the total alkali consumed. Analyses of several synthetic samples containing uranium and nitric acid in a wide range of combinations indicate that the free acidity can be accurately determined by this method, if uranium concentration in the sample is known. The results are compared to those obtained by two other widely used methods, viz., (i) titration of pH7 in the presence of neutral potassium oxalate to suppress hydrolysis and (ii) separation of hydrolyzable ions on a cationic resin and alkali titration of the free acid released. The advantages of and the precision obtained with the present method over the above two methods are discussed. (author)

  5. Kinetic of liquid-liquid extraction for uranyl nitrate and actinides (III) and lanthanides (III) nitrates by amide extractants; Cinetique d`extraction liquide-liquide du nitrate d`uranyle et des nitrates d`actinides (III) et de lanthanides (III) par des extractants a fonction amide

    Energy Technology Data Exchange (ETDEWEB)

    Toulemonde, V [CEA Centre d` Etudes Nucleaires de Saclay, 91 -Gif-sur-Yvette (France); [CEA Centre d` Etudes de la Vallee du Rhone, 30 -Marcoule (France). Dept. d` Exploitation du Retraitement et de Demantelement

    1995-12-20

    The kinetics of liquid-liquid extraction by amide extractants have been investigated for uranyl nitrate (monoamide extractants), actinides (III) and lanthanides (III) nitrates (diamide extractants). The transfer of the metallic species from the aqueous phase to the organic phase was studied using two experimental devices: ARMOLLEX (Argonne Modified Lewis cell for Liquid Liquid Extraction) and RSC (Rotating Stabilized Cell). The main conclusions are: for the extraction of uranyl nitrate by DEHDMBA monoamide, the rate-controlling step is the complexation of the species at the interface of the two liquids. Thus, an absorption-desorption (according to Langmuir theory) reaction mechanism was proposed; for the extraction of actinides (III) and lanthanides (III) nitrates in nitric acid media by DMDBTDMA diamide, the kinetic is also limited by interfacial reactions. The behavior of Americium and Europium is very similar as fare as their reaction kinetics are concerned. (author). 89 refs.

  6. Liquid-liquid extraction kinetics of uranyl nitrate and actinides (III)-lanthanides nitrates by extractants with amide function

    International Nuclear Information System (INIS)

    Toulemonde, V.

    1995-01-01

    Nowadays, the most important part of electric power is generated by fission energy. But spent fuels have then to be reprocessed. The production of these reprocessed materials separately and with a high purity level is done according to a liquid-liquid extraction process (Purex process) with the use of tributyl phosphate as solvent. Optimization studies concerning the extracting agent have been undertaken. This work gives the results obtained for the uranyl nitrate and the actinides (III)-lanthanides (III) nitrates extraction by extractants with amide function (monoamide for U(VI) and diamide for actinides (III) and lanthanides (III)). The extraction kinetics have been studied in the case of a metallic specie transfer from the aqueous phase towards the organic phase. The experiments show that the nitrates extraction kinetics is limited by the complexation chemical reaction of the species at the interface between the two liquids. An adsorption-desorption interfacial reactional mechanism (Langmuir theory) is proposed for the uranyl nitrate. (O.M.)

  7. Study of diamagnetism in uranyl complexes of some Schiff bases

    International Nuclear Information System (INIS)

    Dodwad, S.S.; Sawant, A.S.

    1992-01-01

    Uranyl complexes of Schiff bases obtained by condensing salicylaldehyde with aromatic amines have been isolated and characterised. The complexes have the formula M (LH) 2 (NO 3 ) 2 where M = UO 2 and LH = Schiff base. The magnetic susceptibilities of these complexes have been measured on a Gouy balance. These values have been compared with the computed ones. The percentage deviation between the observed and computed values of molar magnetic susceptibilities clearly show that they are outside experimental error and therefore significant. These deviations have been discussed in the light of VanVleck's, equation for molar susceptibility of polyatomic molecule. (author). 3 refs., 1 tab

  8. Acute toxicity of uranium hexafluoride, uranyl fluoride and hydrogen fluoride

    International Nuclear Information System (INIS)

    Just, R.A.

    1988-01-01

    Uranium hexafluoride (UF 6 ) released into the atmosphere will react rapidly with moisture in the air to form the hydrolysis products uranyl fluoride (UO 2 F 2 ) and hydrogen fluoride (HF). Uranium compounds such as UF 6 and UO 2 F 2 exhibit both chemical toxicity and radiological effects, while HF exhibits only chemical toxicity. This paper describes the development of a methodology for assessing the human health consequences of a known acute exposure to a mixture of UF 6 , UO 2 F 2 , and HF. 4 refs., 2 figs., 5 tabs

  9. Biosolubilization of uranyl ions in uranium ores by hydrophyte plants

    International Nuclear Information System (INIS)

    Cecal, Alexandru; Calmoi, Rodica; Melniciuc-Puica, Nicoleta

    2006-01-01

    This paper investigated the bioleaching of uranyl ions from uranium ores, in aqueous medium by hydrophyte plants: Lemna minor, Azolla caroliniana and Elodea canadensis under different experimental conditions. The oxidation of U(IV) to U(VI) species was done by the atomic oxygen generated in the photosynthesis process by the aquatic plants in the solution above uranium ores. Under identical experimental conditions, the capacity of bioleaching of uranium ores decreases according to the following series: Lemna minor > Elodea canadensis > Azolla caroliniana. The results of IR spectra suggest the possible use of Lemna minor and Elodea canadensis as a biological decontaminant of uranium containing wastewaters. (author)

  10. The system uranyl nitrate-dietyl ether-water. Extraction by water in spray and packed columns from uranyl nitrate-either solutions; El sistema nitrato de uranilo-eter dietilico-agua, extraccion de nitrato de uranilo con agua a partir de disoluciones etereas en columnas de pulverizacion y de relleno

    Energy Technology Data Exchange (ETDEWEB)

    Perez Luina, A; Gutierrez Jodra, L

    1960-07-01

    This paper is a continuation of the one published in Chemical Engineering Progress. Symposium Series, 50, n. 12, 127 (1954). New runs for spray columns, are given and other concentrations in uranyl nitrate for the packed columns. New correlations for the overall H.T.U. are also given. The individual H.T.U. have been grapycally calculated and show that the film resistances have similar values, being independent of the concentration of the ether phase. (Author) 24 refs.

  11. Interpenetrated Uranyl-Organic Frameworks with bor and pts Topology: Structure, Spectroscopy, and Computation.

    Science.gov (United States)

    Liu, Chao; Chen, Fang-Yuan; Tian, Hong-Rui; Ai, Jing; Yang, Weiting; Pan, Qing-Jiang; Sun, Zhong-Ming

    2017-11-20

    Two novel three-dimensional interpenetrated uranyl-organic frameworks, (NH 4 ) 4 [(UO 2 ) 4 (L 1 ) 3 ]·6H 2 O (1) and [(UO 2 ) 2 (H 2 O) 2 L 2 ]·2H 2 O (2), where L 1 = tetrakis(3-carboxyphenyl)silicon and L 2 = tetrakis(4-carboxyphenyl)silicon, were synthesized by a combination of two isomeric tetrahedral silicon-centered ligands with 3-connected triangular [(UO 2 )(COO) 3 ] - and 4-connected dinuclear [(UO 2 ) 2 (COO) 4 ] units, respectively. Structural analyses indicate that 1 possesses a 2-fold interpenetrating anion bor network, while 2 exhibits a 3-fold interpenetrated 4,4-connected neutral network with pts topology. Both compounds were characterized by thermogravimetric analysis and IR, UV-vis, and photoluminescence spectroscopy. A relativistic density functional theory (DFT) investigation on 10 model compounds of 1 and 2 shows good agreement of the structural parameters, stretching vibrational frequencies, and absorption with experimental results; the time-dependent DFT calculations unravel that low-energy absorption bands originate from ligand-to-uranium charge transfer.

  12. Synthesis, structure, and photoluminescence properties of an organically-templated uranyl selenite

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dong-Sheng; Kuang, Han-Mao; Chen, Wen-Tong; Luo, Qiu-Yan; Sui, Yan [Institute of Applied Chemistry, School of Chemistry and Chemical Engineering, Jinggangshan University, Ji' an, Jiangxi 343009 (China)

    2015-09-15

    The organically-templated uranyl selenite, (H{sub 2}en)[(UO{sub 2})(SeO{sub 3})(HSeO{sub 3})](NO{sub 3}).0.5H{sub 2}O (1) (en = 1,2-ethylenediamine) was synthesized and characterized by elemental analyses, IR spectroscopy, TG, and single-crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic system, space group Pbca, with a = 13.170(3) Aa, b = 11.055(2) Aa, c = 18.009(4) Aa, V = 2621.8(9) Aa{sup 3}, M = 1316.19, Z = 4, D{sub cal} = 3.334 g.cm{sup -3}, μ(Mo-K{sub α}) = 17.998 mm{sup -1}, GOF = 1.059, R{sub 1} = 0.0263, wR{sub 2} = 0.0532 [I>2σ(I)]. The X-ray diffraction analysis reveals that compound 1 has a three-dimensional (3D) supramolecular structure. It contains negatively charged [UO{sub 2}(HSeO{sub 3})(SeO{sub 3})]{sup -} inorganic anion layers and is balanced by [H{sub 2}en]{sup 2+} cations and NO{sub 3}{sup -} anions located in the interlayers. Furthermore, the photoluminescence properties of 1 were investigated. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures.

    Science.gov (United States)

    Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

    2012-09-30

    This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144×10(3) J mol(-1). The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. SEPARATION OF BARIUM VALUES FROM URANYL NITRATE SOLUTIONS

    Science.gov (United States)

    Tompkins, E.R.

    1959-02-24

    The separation of radioactive barium values from a uranyl nitrate solution of neutron-irradiated uranium is described. The 10 to 20% uranyl nitrate solution is passed through a flrst column of a cation exchange resin under conditions favoring the adsorption of barium and certain other cations. The loaded resin is first washed with dilute sulfuric acid to remove a portion of the other cations, and then wash with a citric acid solution at pH of 5 to 7 to recover the barium along with a lesser amount of the other cations. The PH of the resulting eluate is adjusted to about 2.3 to 3.5 and diluted prior to passing through a smaller second column of exchange resin. The loaded resin is first washed with a citric acid solution at a pH of 3 to elute undesired cations and then with citric acid solution at a pH of 6 to eluts the barium, which is substantially free of undesired cations.

  15. Bases for DOT exemption uranyl nitrate solution shipments

    International Nuclear Information System (INIS)

    Moyer, R.A.

    1982-07-01

    Uranyl nitrate solutions from a Savannah River Plant reprocessing facility have been transported in cargo tank trailers for more than 20 years without incident during transit. The solution is shipped to Oak Ridge for further processing and returned to SRP in a solid metal form for recycle. This solution, called uranyl nitrate hexahydrate (UNH) solution in Department of Transportation (DOT) regulations, is currently diluted about 2-fold to comply with DOT concentration limits (10% of low specific activity levels) specified for bulk low specific activity (LSA) liquid shipments. Dilution of the process solution increases the number of shipments, the cost of transportation, the cost of shipper preparations, the cost of further reprocessing in the receiving facility to first evaporate the added water, and the total risk to the population along the route of travel. However, the radiological risk remains about the same. Therefore, obtaining an exemption from DOT regulations to permit shipment of undiluted UNH solution, which is normally about two times the present limit, is prudent and more economical. The radiological and nonradiological risks from shipping a unit load of undiluted solution are summarized for the probable route. Data and calculations are presented on a per load or per shipment basis throughout this memorandum to keep it unclassified

  16. Modulation of the unpaired spin localization in Pentavalent Uranyl Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Vetere, V.; Maldivi, P.; Mazzanti, M. [CEA Grenoble, INAC, SCIB, laboratoire de reconnaissance ionique et chimie de coordination, 38 (France); Vetere, V. [UMR5626, laboratoire de chimie et physique quantique, universite de Toulouse, 31 - Toulouse (France)

    2010-06-15

    The electronic structure of various complexes of pentavalent uranyl species, namely UO{sub 2}{sup +}, is described, using DFT methods, with the aim of understanding how the structure of the ligands may influence the localisation of the unpaired 5f electron of uranium (V) and, finally, the stability of such complexes towards oxidation. Six complexes have been inspected: [UO{sub 2}py{sub 5}]{sup +} (1), [(UO{sub 2}py{sub 5})KI{sub 2}] (2), [UO{sub 2}(salan-{sup t}Bu{sub 2})(py)K] (3), [UO{sub 2}(salophen-{sup t}Bu{sub 2})(thf)K] (4), [UO{sub 2}(salen-{sup t}Bu{sub 2})(py)K] (5), [and UO{sub 2}-cyclo[6]pyrrole]{sup 1-} (6), chosen to explore various ligands. In the five first complexes, the UO{sub 2}{sup +} species is well identified with the unpaired electron localized on the 5f uranium orbital. Additionally, for the salan, salen and salophen ligands, some covalent interactions have been observed, resulting from the presence of both donor and acceptor binding sites. In contrast, the last complex is best described by a UO{sub 2}{sup 2+} uranyl (VI) coordinated by the anionic radical cyclo-pyrrole, the highly delocalized p orbitals set stabilizing the radical behaviour of this ligand. (authors)

  17. Photophysics of the excited uranyl ion in aqueous solutions

    International Nuclear Information System (INIS)

    Formosinho, S.J.; Miguel, M. da G.M.

    1985-01-01

    The effect of the micelles of Triton X-100 on the biexponential decay of (UO 2 2+ )* has been investigated. Data are analysed in terms of a reversible crossing mechanism for the decay. Azulene fluorescence quenching and 13 C n.m.r. studies strongly suggest that uranyl ions are able to penetrate deep inside the micelle core. Micelle quenching for the reversible decay of (UO 2 2+ )* occurs in the interior (ksub(q) = 3 x 10 10 dm 3 mol -1 s -1 ) and at the surface (Ksub(q) = 1.5 x 10 9 mol -1 dm 3 s -1 ) of the micelles. The latter process has a rate virtually identical to that for the free surfactant molecules. Penetration of (UO 2 2+ )* inside the non-polar regions of the micelle core increases solvent exchange rates by ca. two orders of magnitude. Uranyl-ion excimers are formed in occupied micelles. The quenching processes decrease strongly for these species because excimers do not penetrate the micelles. (author)

  18. Effect of the substitutional groups on the electrochemistry, kinetic of thermal decomposition and kinetic of substitution of some uranyl Schiff base complexes

    Energy Technology Data Exchange (ETDEWEB)

    Asadi, Zahra; Nasrollahi, Rahele; Ranjkeshshorkaei, Mohammad; Firuzabadi, Fahimeh Dehghani [Shiraz Univ. (Iran, Islamic Republic of). Chemistry Dept.; Dusek, Michal; Fejfarova, Karla [ASCR, Prague (Czech Republic). Inst. of Physics

    2016-05-15

    Uranyl(VI) complexes, [UO{sub 2}(X-saloph)(solvent)], where saloph denotes N,N{sup '}-bis(salicylidene)-1,2-phenylenediamine and X = NO{sub 2}, Cl, Me, H; were synthesized and characterized by 61H NMR, IR, UV-Vis spectroscopy, thermal gravimetry (TG), cyclic voltammetry, elemental analysis (C.H.N) and X-ray crystallography. X-ray crystallography of [UO{sub 2}(4-nitro-saloph)(DMF)] revealed coordination of the uranyl by the tetradentate Schiff base ligand and one solvent molecule, resulting in seven-coordinated uranium. The complex of [UO{sub 2}(4-nitro-saloph)(DMF)] was also synthesized in nano form. Transmission electron microscopy image showed nano-particles with sizes between 30 and 35 nm. The TG method and analysis of Coats-Redfern plots revealed that the kinetics of thermal decomposition of the complexes is of the first-order in all stages. The kinetics and mechanism of the exchange reaction of the coordinated solvent with tributylphosphine was investigated by spectrophotometric method. The second-order rate constants at four temperatures and the activation parameters showed an associative mechanism for all corresponding complexes with the following trend: 4-Nitro > 4-Cl > H > 4-Me. It was concluded that the steric and electronic properties of the complexes were important for the reaction rate. For analysis of anticancer properties of uranyl Schiff base complexes, cell culture and MTT assay was carried out. These results showed a reduction of jurkat cell line concentration across the complexes.

  19. Enhanced Adsorption and Recovery of Uranyl Ions by NikR Mutant-Displaying Yeast

    Directory of Open Access Journals (Sweden)

    Kouichi Kuroda

    2014-04-01

    Full Text Available Uranium is one of the most important metal resources, and the technology for the recovery of uranyl ions (UO22+ from aqueous solutions is required to ensure a semi-permanent supply of uranium. The NikR protein is a Ni2+-dependent transcriptional repressor of the nickel-ion uptake system in Escherichia coli, but its mutant protein (NikRm is able to selectively bind uranyl ions in the interface of the two monomers. In this study, NikRm protein with ability to adsorb uranyl ions was displayed on the cell surface of Saccharomyces cerevisiae. To perform the binding of metal ions in the interface of the two monomers, two metal-binding domains (MBDs of NikRm were tandemly fused via linker peptides and displayed on the yeast cell surface by fusion with the cell wall-anchoring domain of yeast α-agglutinin. The NikRm-MBD-displaying yeast cells with particular linker lengths showed the enhanced adsorption of uranyl ions in comparison to the control strain. By treating cells with citrate buffer (pH 4.3, the uranyl ions adsorbed on the cell surface were recovered. Our results indicate that the adsorption system by yeast cells displaying tandemly fused MBDs of NikRm is effective for simple and concentrated recovery of uranyl ions, as well as adsorption of uranyl ions.

  20. Surface complexation modeling of uranyl adsorption on corrensite from the Waste Isolation Pilot Plant Site

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang-Won; Leckie, J.O. [Stanford Univ., CA (United States); Siegel, M.D. [Sandia National Labs., Albuquerque, NM (United States)

    1995-09-01

    Corrensite is the dominant clay mineral in the Culebra Dolomite at the Waste Isolation Pilot Plant. The surface characteristics of corrensite, a mixed chlorite/smectite clay mineral, have been studied. Zeta potential measurements and titration experiments suggest that the corrensite surface contains a mixture of permanent charge sites on the basal plane and SiOH and AlOH sites with a net pH-dependent charge at the edge of the clay platelets. Triple-layer model parameters were determined by the double extrapolation technique for use in chemical speciation calculations of adsorption reactions using the computer program HYDRAQL. Batch adsorption studies showed that corrensite is an effective adsorbent for uranyl. The pH-dependent adsorption behavior indicates that adsorption occurs at the edge sites. Adsorption studies were also conducted in the presence of competing cations and complexing ligands. The cations did not affect uranyl adsorption in the range studied. This observation lends support to the hypothesis that uranyl adsorption occurs at the edge sites. Uranyl adsorption was significantly hindered by carbonate. It is proposed that the formation of carbonate uranyl complexes inhibits uranyl adsorption and that only the carbonate-free species adsorb to the corrensite surface. The presence of the organic complexing agents EDTA and oxine also inhibits uranyl sorption.

  1. Influence of Acidity on Uranyl Nitrate Association in Aqueous Solutions: A Molecular Dynamics Simulation Study

    International Nuclear Information System (INIS)

    de Almeida, Valmor F.; Cui, Shengting; Khomami, Bamin; Ye, Xianggui; Smith, Rodney Bryan

    2010-01-01

    Uranyl ion complexation with water and nitrate is a key aspect of the uranium/plutonium extraction process. We have carried out a molecular dynamics simulation study to investigate this complexation process, including the molecular composition of the various complex species, the corresponding structure, and the equilibrium distribution of the complexes. The observed structures of the complexes suggest that in aqueous solution, uranyls are generally hydrated by 5 water molecules in the equatorial plane. When associating with nitrate ions, a water molecule is replaced by a nitrate ion, preserving the five-fold coordination and planar symmetry. Analysis of the pair correlation function between uranyl and nitrate suggests that nitrates bind to uranyl in aqueous solution mainly in a monodentate mode, although a small portion of bidentates occur. Dynamic association and dissociation between uranyls and nitrates take place in aqueous solution with a substantial amount of fluctuation in the number of various uranyl nitrate species. The average number of the uranyl mononitrate complexes shows a dependence on acid concentration consistent with equilibrium-constant analysis, namely, the concentration of [UO2NO3]+ increases with nitric acid concentration.

  2. Surface complexation modeling of uranyl adsorption on corrensite from the Waste Isolation Pilot Plant Site

    International Nuclear Information System (INIS)

    Park, Sang-Won; Leckie, J.O.; Siegel, M.D.

    1995-09-01

    Corrensite is the dominant clay mineral in the Culebra Dolomite at the Waste Isolation Pilot Plant. The surface characteristics of corrensite, a mixed chlorite/smectite clay mineral, have been studied. Zeta potential measurements and titration experiments suggest that the corrensite surface contains a mixture of permanent charge sites on the basal plane and SiOH and AlOH sites with a net pH-dependent charge at the edge of the clay platelets. Triple-layer model parameters were determined by the double extrapolation technique for use in chemical speciation calculations of adsorption reactions using the computer program HYDRAQL. Batch adsorption studies showed that corrensite is an effective adsorbent for uranyl. The pH-dependent adsorption behavior indicates that adsorption occurs at the edge sites. Adsorption studies were also conducted in the presence of competing cations and complexing ligands. The cations did not affect uranyl adsorption in the range studied. This observation lends support to the hypothesis that uranyl adsorption occurs at the edge sites. Uranyl adsorption was significantly hindered by carbonate. It is proposed that the formation of carbonate uranyl complexes inhibits uranyl adsorption and that only the carbonate-free species adsorb to the corrensite surface. The presence of the organic complexing agents EDTA and oxine also inhibits uranyl sorption

  3. Use of uranyl nitrate as a shift reagent in polar and inert solvents

    International Nuclear Information System (INIS)

    Nosov, B.P.

    1988-01-01

    This work examines the effect of uranyl nitrate as a shift reagent on the PMR spectra of different organic molecules in polar and inert solvents. In order to identify the coordination site of the uranyl ion, its effect on the spectra of amino acids and acetic or propionic acids in water was compared. It was found that the induced shifts of the protons in the corresponding positions of the different acids after addition of uranyl nitrate agreed to within ±0.01 ppm. When nitrogenous bases such as diethylamine and pyridine were added to solutions of the carboxylic acids with uranyl nitrate, an increase in the induced chemical shift of the resonance signals occurred. These facts suggest the coordination of the uranyl ion with the carboxyl oxygen both for acetic and propionic acids and for amino acids. The authors established that the addition of uranyl nitrate to solutions of organic compounds caused different downfield shifts of the resonance signals from the protons. In polar solvents shifts induced by uranyl nitrate in the PMR spectra of carboxylic acids occur only when nitrogenous bases are added

  4. Hydrothermal Synthesis of Disulfide-Containing Uranyl Compounds. In Situ Ligand Synthesis versus Direct Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Rowland, Clare E. [George Washington Univ., Washington, DC (United States); Belai, Nebebech [George Washington Univ., Washington, DC (United States); Knope, Karah E. [George Washington Univ., Washington, DC (United States); Cahill, Christopher L. [George Washington Univ., Washington, DC (United States)

    2010-01-29

    Three disulfide-containing uranyl compounds, [UO2(C7H4O2S)3]·H2O (1), [UO2(C7H4O2S)2(C7H5O2S)] (2), and [UO2(C7H4O2S)4] (3) have been hydrothermally synthesized. Both in situ disulfide bond formation from 3- and 4-mercaptobenzoic acid (C7H5O2S, MBA) to yield 3,3'- and 4,4'-dithiobisbenzoic acid (C14H8O4S2, DTBA) and direct assembly with the presynthesized dimeric ligands have been explored. While the starting materials 4-MBA and 4,4'-DTBA both yield 2 via in situ ligand synthesis and direct assembly, respectively, we observe the formation of 1 from the starting material 3-MBA via in situ ligand synthesis and of 3 from the direct assembly of the uranyl cation with 3,3'-DTBA. Concurrently with the synthesis of 1 and 2, we have observed the in situ formation of the crystalline dimeric organic species, 3,3'-DTBA, [(C7H5O2S)2] (4) and 4,4'-DTBA, [(C7H5O2S)2] (5). Herein we report the synthesis and crystallographic characterization of 1-5, as well as observations regarding the utility of product formation via direct assembly and in situ ligand synthesis.

  5. Structural study of the uranyl and rare earth complexation functionalized by the CMPO; Etude structurale de la complexation de l'uranyle et des ions lanthanides par des calixarenes fonctionnalises par le CMPO

    Energy Technology Data Exchange (ETDEWEB)

    Cherfa, S

    1998-12-10

    In view of reducing the volume of nuclear waste solutions, a possible way is to extract simultaneously actinide and lanthanide ions prior to their ulterior separation.. Historically, the two extractant families used for nuclear waste reprocessing are the phosphine oxides and the CMPO (Carbamoyl Methyl Phosphine Oxide). For a better understanding of the complexes formed during extraction, we undertook structural studies of the complexes formed between uranyl and lanthanide (III) ions and the two classes of ligands cited above. These studies have been performed by X-ray diffraction on single crystals. Recently, a new type of extractants of lanthanide (III) and actinide (III) ions has been developed. When the Organic macrocycle called calixarene (an oligomeric compound resulting from the poly-condensation of phenolic units) is functionalized by a CMPO ligand, the extracting power, in terms of yield and selectivity towards lightest lanthanides, is greatly enhanced compared to the one measured for the single CMPO. Our X-ray diffraction studies allowed us to characterise, in terms of stoichiometry and monodentate or bidentate coordination mode of the CMPO functions, the complexes of calix[4]arene-CMPO (with four phenolic units) with lanthanide nitrates and uranyl. These different steps of characterisation enabled us to determine the correlation between the structures of the complexes and both selectivity and exacerbation of the extracting power measured in the liquid phase. (author)

  6. Study of the influence of the citric and oxalic acid in the uranyl sorption in ZrP2O7 for their use in contention barriers

    International Nuclear Information System (INIS)

    Garcia G, N.

    2009-01-01

    Countries which produce electricity by nuclear means, such as Mexico, need to develop a technology for that at long term safe containment of nuclear waste that are produced in nuclear power plants, for now, the arrangement of these is made by international companies, as which is extremely expensive. The most accepted proposal for the containment of radioactive waste is the Deep Geological Repository (DGR), which consists of a number of natural barriers and of engineering barriers. Currently, barriers to engineering and materials that the make up are still under study, because must meet a series of structural criteria and chemical such as high insolubility, thermal and chemical stability with ionizing radiation. The surface must have adsorbed features of ions and organic compounds dissolved in infiltration water that could penetrate for a crack in the DGR. This study focuses, as first stage, is the uranyl sorption on zirconium diphosphate in various conditions of time, concentration and ph, then evaluates the influence of citric acid and oxalic acid on the sorption of uranyl on ZrP 2 O 7 , in order to model the behaviour of alpha emitters that are dissolved by percolating water laden with salts and organic matter, that infiltrates might during catastrophic events in the DGR. It was confirmed the purity of the zirconium diphosphate because it was synthesized from sea sand with the physicochemical characterization and superficial. The proposed methodology included elemental analysis by neutron activation and X-ray emission induced by charged particles, functional group analysis with infrared spectroscopy, morphology with scanning electron microscopy, crystallinity with transmission electron microscopy and X-ray diffraction. For properties surface was determined, the specific area using Bet multipoint technique, acidity constants in the FITEQL 4.0 program, the hydration time was obtained from literature, the point of zero charge was identified with a mass titration and

  7. Uranyl and/or rare-earth mellitates in extended organic-inorganic networks: A unique case of hetero-metallic cation-cation interaction with U-VI=O-Ln(III) bonding (Ln = Ce, Nd)

    International Nuclear Information System (INIS)

    Volkringer, Christophe; Henry, Natacha; Grandjean, Stephane; Loiseau, Thierry

    2012-01-01

    A series of uranyl and lanthanide (trivalent Ce, Nd) mellitates (mel) has been hydrothermally synthesized in aqueous solvent. Mixtures of these 4f and 5f elements also revealed the formation of a rare case of lanthanide-uranyl coordination polymers. Their structures, determined by XRD single-crystal analysis, exhibit three distinct architectures. The pure lanthanide mellitate Ln 2 (H 2 O) 6 (mel) possesses a 3D framework built up from the connection of isolated LnO 6 (H 2 O) 3 polyhedra (tri-capped trigonal prism) through the mellitate ligand. The structure of the uranyl mellitate (UO 2 ) 3 (H 2 O) 6 - (mel).11.5H 2 O is lamellar and consists of 8-fold coordinated uranium atoms linked to each other through the organic ligand giving rise to the formation of a 2D 3 6 net. The third structural type, (UO 2 ) 2 Ln(OH)(H 2 O) 3 (mel).2.5H 2 O, involves direct oxygen bondings between the lanthanide and uranyl centers, with the isolation of a hetero-metallic dinuclear motif. The 9-fold coordinated Ln cation, LnO 5 (OH)(H 2 O) 3 , is linked to the 7-fold coordinated uranyl (UO 2 )O-4(OH) (pentagonal bipyramid) via one μ 2 -hydroxo group and one μ 2 -oxo group. The latter is shared between the uranyl bonding (U=O = 1.777(4)1.779(6) angstrom) and a long Ln-O bonding (Ce-O = 2.822(4) angstrom; Nd-O = 2.792(6) angstrom). This unusual linkage is a unique illustration of the so-called cation cation interaction associating 4f and 5f metals. The dinuclear motif is then further connected through the mellitate ligand, and this generates organic inorganic layers that are linked to each other via discrete uranyl (UO 2 )O 4 units (square bipyramid), which ensure the three-dimensional cohesion of the structure. The mixed U-Ln carboxylate is thermally decomposed from 260 to 280 degrees C and then transformed into the basic uranium oxide (U 3 O 8 ) together with U-Ln oxide with the fluorite structural type ('(Ln,U)O 2 '). At 1400 degrees C, only fluorite type '(Ln,U)O 2 ' is formed with

  8. XAFS spectroscopic study of uranyl coordination in solids and aqueous solution

    International Nuclear Information System (INIS)

    Thompson, H.A.; Brown, G.E. Jr.; Parks, G.A.

    1997-01-01

    To evaluate the ability of X-ray absorption fine structure (XAFS) spectroscopy to elucidate the coordination environment of U 6+ at the solid-water interface, we conducted an in-depth analysis of experimental XAFS data from U 6+ solid and solution model compounds. Using the ab initio XAFS code FEFF6, we calculated phase-shift and amplitude functions for fitting experimental data. The code FEFF6 does a good job of reproducing experimental data and is particularly valuable for providing phase-shift and amplitude functions for neighboring atoms whose spectral contributions are difficult to isolate from experimental data because of overlap of Fourier transform features. In solid-phase model compounds at ambient temperature, we were able to fit spectral contributions from axial O (1.8 Angstrom), equatorial O (2.2-2.5 Angstrom), N (2.9 Angstrom), C (2.9 Angstrom), Si (3.2 Angstrom), P (3.6 Angstrom), distant 0 (4.3 Angstrom), and U (4.0, 4.3, 4.9, and 5.2 Angstrom) atoms. Contributions from N, C, Si, P, distant O, and distant U (4.9 and 5.2 Angstrom) are weak and therefore might go undetected in a sample of unknown composition. Lowering the temperature to 10 K extends detection of U neighbors to 7.0 Angstrom. The ability to detect these atoms suggests that XAFS might be capable of discerning inner-sphere U sorption at solid aluminosilicate-water interfaces. XAFS should definitely detect multinuclear U complexes and precipitates. Multiple-scattering paths are minor contributors to uranyl XAFS beyond k = 3 Angstrom -1 . Allowing shell-dependent disorder parameters (σ 2 ) to vary, we observed narrow ranges of σ 2 values for similar shells of neighboring atoms. Knowledge of these ranges is necessary to constrain the fit of XAFS spectra for unknowns. Finally, we found that structures reported in the literature for uranyl diacetate and rutherfordine are not completely correct. 50 refs., 6 figs., 2 tabs

  9. Study of structural phase transformation and hysteresis behavior of inverse-spinel α-ferrite nanoparticles synthesized by co-precipitation method

    Science.gov (United States)

    Dabagh, Shadab; Chaudhary, Kashif; Haider, Zuhaib; Ali, Jalil

    2018-03-01

    Substitution of cobalt (Co2+) ions in cobalt ferrite (CoFe2O4) with copper (Cu2+) and aluminum (Al3+) ions allows variations in their electric and magnetic properties which can be optimized for specific applications. In this article, synthesis of inverse-spinel Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) nanoparticles by substituting Cu2+ and Al3+ ions in CoFe2O4 via co-precipitation method is reported. By controlling copper and aluminum (Cu-Al) substituent ratio, the magnetic moment and coercivity of synthesized cobalt ferrite nanoparticles is optimized. The role of substituents on the structure, particle size, morphology, and magnetic properties of nano-crystalline ferrite is investigated. The Co1-xCuxFe2-xAlxO4 (0.0 ≤ x≤ 0.8) nanoparticles with crystallite size in the range of 23.1-26.5 nm are observed, 26.5 nm for x = 0.0-23.1 nm for x = 0.8. The inverse-spinel structure of synthesized Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) nano-particles is confirmed by characteristic vibrational bands at tetrahedral and octahedral sites using Fourier transform infrared spectroscopy. A decreases in coercive field and magnetic moment is observed as Cu-Al contents are increased (x = 0.0-0.8). The positive anisotropy of synthesized particles Co1-xCuxFe2-xAlxO4 (0.0 ≤ x ≤ 0.8) is obtained in the range 1.96 × 105 J/m3 for x = 0.0 to 0.29 × 105 J/m3 for x = 0.8.

  10. Unusual case of a polar copper(II) uranyl phosphonate that fluoresces

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, A.G.D.; Albrecht-Schmitt, Th.E. [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, 156 Fitzpatrick Hall, University of Notre Dame, Notre Dame, Indiana (United States)

    2010-06-15

    A polar Cu(II) uranyl diphosphonate, Cu(H{sub 2}O){sub 4}(UO{sub 2}){sub 3}(H{sub 2}O){sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{sub 2}.5H{sub 2}O, has been prepared under mild hydrothermal conditions. This compound has direct linkages between the oxo atoms of the uranyl moieties and the Cu(II) centers. Despite the presence of Cu(II) in the structure, vibronically-coupled emission is still observed, most likely because there are two crystallographically unique uranyl moieties, only one of which bonds to Cu(II). (authors)

  11. Density Functional Studies on the Complexation and Spectroscopy of Uranyl Ligated with Acetonitrile and Acetone Derivatives

    International Nuclear Information System (INIS)

    Schoendorff, George E.; Windus, Theresa L.; De Jong, Wibe A.

    2009-01-01

    The coordination of nitrile (acetonitrile, propionitrile, and benzonitrile) and carbonyl (formaldehyde, ethanal, and acetone) ligands to the uranyl dication (UO22+) has been examined using density functional theory (DFT) utilizing relativistic effective core potentials (RECPs). Complexes containing up to six ligands have been modeled for all ligands except formaldehyde, for which no minimum could be found. A comparison of relative binding energies indicates that five coordinate complexes are predominant while a six coordinate complex involving propionitrile ligands might be possible. Additionally, the relative binding energy and the weakening of the uranyl bond is related to the size of the ligand and, in general, nitriles bind more strongly to uranyl than carbonyls.

  12. Removal of uranyl ions from residual waters using some algae types

    International Nuclear Information System (INIS)

    Cecal, A.; Palamaru, I.; Humelnicu, D.; Popa, K.; Salaru, V.V.; Rudic, V.; Gulea, A.

    1999-01-01

    This paper deals with a study on the bioaccumulation of uranyl ions resulted from residual effluents by means of some microbiological collectors: Scenedesmus quadricauda, Anabaena karakumica, Calothrix brevissima, Penicillinium sp, as well as the Glucid extract of Porphyridium cruentum, under various experimental conditions. The retaining degree of the bioaccumulated uranyl ions, as well as the leaching degree, in HCl and H 2 O media, of the same ions previously retained on algae were established. The retaining degree decreases in the series: Scenedesmus quadricauda > Anabaena karakumica > Penicillinium sp > Calothrix brevissima. The leaching effect of bioaccumulated uranyl ions is higher in hydrochloric acid than in water. (author)

  13. Removal of uranyl ions from residual waters using some algae types

    International Nuclear Information System (INIS)

    Cecal, Al.; Rudic, V.; Gulea, A.; Palamaru, I.; Humelnicu, D.; Salaru, V.V.; Popa, K.

    1997-01-01

    This paper deals with a study on the bioaccumulation of uranyl ions resulted from residual effluents, by means of some microbiological collectors: Scenedesmus quadricauda, Anabaena karakumica, Calothrix brevissima, Penicillium sp, as well as the Glucide extract of Porphyridium cruentum, in several experimental conditions. The retaining degree of the bioaccumulated uranyl ions, as well as the leaching degree, in HCl and H 2 O media, of the same ions previously retained on algae, were karakumica >Penicillium sp> Calothrix brevissima. The leaching effect of bioaccumulated uranyl ions is higher in hydrochloric acid then in water. (authors)

  14. Physico-chemical study of new functionalized surfactants having thermo sensitive de-mixing behaviour: use in extraction of uranyl nitrate

    International Nuclear Information System (INIS)

    Prevost, S.

    2006-04-01

    New thermo-sensitive functionalized surfactants with metal-chelating properties have been developed and their physical-chemistry studied. They associate a polyethoxylated nonionic surfactant (CiEj) block and a amino-acid residue as a chelating group. Functionalization preserves both properties of the thermo-sensitive surfactant moiety and the chelating group, a diamide closed to uranyl ionophore.The complexing group participates to the polar head group of the surfactant, increasing the area per molecule. As a result, functionalized surfactants form spherical micelles when diluted in water, and the concentrated part of their phase diagrams exhibits structures having higher curvatures than the nonionic precursor CiEj. The structure of the uranyl - diamide complex has been elucidated by NMR and ESI-MS and is of the type UO 2 (NO 3 ) 2 .L; the associated complexation constant, which is very low, has been evaluated by 1 H NMR.A nitrate salt, LiNO 3 , is added at high concentration to improve complexation. The effect of this salt has been analyzed, and was found to be rather similar to the effect on classical CiEj. When uranyl nitrate complexation occurs, the cloud point decreases dramatically, together with the reduction of the area per head group at micelle/solution interface. This effect can be minimized by using a nonionic precursor having a larger polar head group. The functionalized surfactants have been tested in the cloud point extraction of uranyl nitrate, and have proved their efficiency. Those results demonstrate the viability of the functionalized surfactants design, with a covalent link between a thermo-sensitive surfactant block and a chelating group. (author)

  15. Structure and dynamics of the uranyl tricarbonate complex in aqueous solution: insights from quantum mechanical charge field molecular dynamics.

    Science.gov (United States)

    Tirler, Andreas O; Hofer, Thomas S

    2014-11-13

    This investigation presents the characterization of structural and dynamical properties of uranyl tricarbonate in aqueous solution employing an extended hybrid quantum mechanical/molecular mechanical (QM/MM) approach. It is shown that the inclusion of explicit solvent molecules in the quantum chemical treatment is essential to mimic the complex interaction occurring in an aqueous environment. Thus, in contrast to gas phase cluster calculations on a quantum chemical level proposing a 6-fold coordination of the three carbonates, the QMCF MD simulation proposes a 5-fold coordination. An extensive comparison of the simulation results to structural and dynamical data available in the literature was found to be in excellent agreement. Furthermore, this work is the first theoretical study on a quantum chemical level of theory able to observe the conversion of carbonate (CO₃²⁻) to bicarbonate (HCO₃⁻) in the equatorial coordination sphere of the uranyl ion. From a comparison of the free energy ΔG values for the unprotonated educt [UO₂(CO₃)₃]⁴⁻ and the protonated [UO₂(CO₃)₂(HCO₃)]³⁻, it could be concluded that the reaction equilibrium is strongly shifted toward the product state confirming the benignity for the observed protonation reaction. Structural properties and the three-dimensional arrangement of carbonate ligands were analyzed via pair-, three-body, and angular distributions, the dynamical properties were evaluated by hydrogen-bond correlation functions and vibrational power spectra.

  16. Ionic flotation of complexing oxyanions. Thermodynamics of uranyl complexation in a sulfuric medium. Definition of selectivity conditions of the process

    International Nuclear Information System (INIS)

    Bouzat, G.

    1987-01-01

    Oxyanion ionic flotation process with dodecylamine hydrochloride as collector is studied by investigation of flotation and filtration recovery curves, suspension turbidity, conductimetric measurements, and solubility of ionic species. The process is controlled by chemical reactions of precipitation and by adsorption of surfactant confering hydrophobic or hydrophilic surface properties to the solid phase respectively when one or two monolayers of surfactant are successively adsorbed. Equilibrium constants (in terms of activity) of the uranium (VI) complexation with sulphate oxyanions are calculated through Raman spectroscopic study of uranyl sulphate aqueous solutions. The complexation results in a shift of the symmetrical stretching vibration band of U0 2 to low wavenumbers and an increase of their cross section. The solubility curves of ionic species in the precipitation of uranyl -sulphate complexes by dodecylamine hydrochloride are modelled. The knowledge of solubility products, activity coefficients of the species and critical micellar concentration of the surfactant allow the modelling of flotation recovery curves. Temperature and collector structure modifications are studied in terms of optimization parameters and uranium extraction of mine drainage water is processed. Residual concentration of surfactant is considerably lowered by adsorption on montmorillonite

  17. Determination of total and extractable hydrogen peroxide in organic and aqueous solutions of uranyl nitrate

    International Nuclear Information System (INIS)

    Goodall, Ph.

    1999-01-01

    The development of a spectrophotometric method for the determination of hydrogen peroxide in uranyl nitrate solutions is reported. The method involves the measurement of the absorbance at 520 mm of a vanadyl peroxide species. This species was formed by the addition of a reagent consisting of vanadium (V) (50 mmol x dm -3 ) in dilute sulphuric acid (2 mol x dm -3 H 2 SO 4 ). This reagent, after dilution, was also used as an extractant for organic phase samples. The method is simple and robust and tolerant of nitric acid and U(VI). Specificity and accuracy were improved by the application of solid phase extraction techniques to remove entrained organic solvents and Pu(VI). Reverse phase solid phase extraction was used to clean-up aqueous samples or extracts which were contaminated with entrained solvent. A solid phase extraction system based upon an extraction chromatography system was used to remove Pu(IV). Detection limits of 26 μmol x dm -3 (0.88 μg x cm -3 ) or 7 μmol x dm -3 (0.24 μg x cm -3 ) for, respectively, a 1 and 4 cm path length cell were obtained. Precisions of RSD = 1.4% and 19.5% were obtained at the extremes of the calibration curve (5 mmol x dm -3 and 50 μmol x dm -3 H 2 O 2 , 1 cm cell). The introduction of the extraction and clean-up stages had a negligible effect upon the precision of the determination. The stability of an organic phase sample was tested and no loss of analyte could be discerned over a period of at least 5 days. (author)

  18. Charge-density matching in organic-inorganic uranyl compounds

    International Nuclear Information System (INIS)

    Krivovichev, S.V.; Krivovichev, S.V.; Tananaev, I.G.; Myasoedov, B.F.

    2007-01-01

    Single crystals of [C 10 H 26 N 2 ][(UO 2 )(SeO 4 ) 2 (H 2 O)](H 2 SeO 4 ) 0.85 (H 2 O) 2 (1), [C 10 H 26 N 2 ][(UO 2 )(SeO 4 ) 2 ] (H 2 SeO 4 ) 0.50 (H 2 O) (2), and [C 8 H 20 N] 2 [(UO 2 )(SeO 4 ) 2 (H 2 O)] (H 2 O) (3) were prepared by evaporation from aqueous solution of uranyl nitrate, selenic acid and the respective amines. The structures of the compounds have been solved by direct methods and structural models have been obtained. The structures of the compounds 1, 2, and 3 contain U and Se atoms in pentagonal bipyramidal and tetrahedral coordinations, respectively. The UO 7 and SeO 4 polyhedra polymerize by sharing common O atoms to form chains (compound 1) or sheets (compounds 2 and 3). In the structure of 1, the layers consisting of hydrogen-bonded [UO 2 (SeO 4 ) 2 (H 2 O)] 2- chains are separated by mixed organic-inorganic layers comprising from [NH 3 (CH 2 ) 10 NH 3 ] 2+ molecules, H 2 O molecules, and disordered electroneutral (H 2 SeO 4 ) groups. The structure of 2 has a similar architecture but a purely inorganic layer is represented by a fully connected [UO 2 (SeO 4 ) 2 ] 2- sheet. The structure of 3 does not contain disordered (H 2 SeO 4 ) groups but is based upon alternating [UO 2 (SeO 4 ) 2 (H 2 O)] 2- sheets and 1.5-nm-thick organic blocks consisting of positively charged protonated octylamine molecules, [NH 3 (CH 2 ) 7 CH 3 ] + . The structures may be considered as composed of anionic inorganic sheets (2D blocks) and cationic organic blocks self-organized according to competing hydrophilic-hydrophobic interactions. Analysis of the structures allows us to conclude that the charge-density matching principle is observed in uranyl compounds. In order to satisfy some basic peculiarities of uranyl (in general, actinyl) chemistry, it requires specific additional mechanisms: (a) in long-chain-amine-templated compounds, protonated amine molecules inter-digitate; (b) in long-chain-diamine-templated compounds, incorporation of acid-water interlayers into

  19. The application of time-resolved luminescence spectroscopy to a remote uranyl sensor

    International Nuclear Information System (INIS)

    Varineau, P.T.; Duesing, R.; Wangen, L.E.

    1991-01-01

    Time resolved luminescence spectroscopy is an effective method for the determination of a wide range of uranyl concentrations in aqueous samples. We have applied this technique to the development of a remote sensing device using fiber optic cables coupled with a micro flow cell in order to probe for uranyl in aqueous samples. This sensor incorporates a Nafion membrane through which UO 2 2+ can diffuse in to a reaction/analysis chamber which holds phosphoric acid, a reagent which enhances the uranyl luminescence intensity and lifetime. With this device, anionic and fluorescing organic interferences could be eliminated, allowing for the determination of uranyl over a concentration range of 10 4 to 10 -9 M. 17 refs., 5 figs

  20. Aggregation-induced emission active tetraphenylethene-based sensor for uranyl ion detection.

    Science.gov (United States)

    Wen, Jun; Huang, Zeng; Hu, Sheng; Li, Shuo; Li, Weiyi; Wang, Xiaolin

    2016-11-15

    A novel tetraphenylethene-based fluorescent sensor, TPE-T, was developed for the detection of uranyl ions. The selective binding of TPE-T to uranyl ions resulted in a detectable signal owing to the quenching of its aggregation-induced emission. The developed sensor could be used to visually distinguish UO2(2+) from lanthanides, transition metals, and alkali metals under UV light; the presence of other metal ions did not interfere with the detection of uranyl ions. In addition, TPE-T was successfully used for the detection of uranyl ions in river water, illustrating its potential applications in environmental systems. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Uranyl determination using pyridylazoresorcinol as complexing active by adsorb voltametry technique with cathodic redissolution

    International Nuclear Information System (INIS)

    Ohara, A.K.; Farias, P.A.M.

    1990-01-01

    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)

  2. The uranyl influence on a mutation process in germ and somatic cells of mice

    International Nuclear Information System (INIS)

    Kostrova, L.N.; Mosseh, I.B.; Molofej, V.P.

    2008-01-01

    The mutagenic effect of uranyl was revealed by the chromosome rearrangement test in germ and somatic cells of mice. The effect value depended on duration of substance administration into organism. (authors)

  3. Sorption rate of uranyl ions by hyphan cellulose exchangers and by hydrated titanium dioxide

    International Nuclear Information System (INIS)

    Ambe, F.; Burba, P.; Lieser, K.H.

    1979-01-01

    Sorption of uranyl ions by the cellulose exchanger Hyphan proceeds rather fast. Two steps are observed with half-times of the order of 10 s and 2 min. The majority of the uranyl ions is bound in 1 min. Sorption of uranyl ions by titanium dioxide is a very slow process. For particle sizes between 0,1 and 0,5 mm the half-time is about 3 h and equilibrium is attained in about 1 day. The effect of stirring suspensions of inorganic sorbents like titanium dioxide in solution is investigated in detail. Sorption of uranyl ions by titanium dioxide and change in pH in solution are measured simultaneously as a function of time. (orig.) [de

  4. Giant regular polyhedra from calixarene carboxylates and uranyl

    Science.gov (United States)

    Pasquale, Sara; Sattin, Sara; Escudero-Adán, Eduardo C.; Martínez-Belmonte, Marta; de Mendoza, Javier

    2012-01-01

    Self-assembly of large multi-component systems is a common strategy for the bottom-up construction of discrete, well-defined, nanoscopic-sized cages. Icosahedral or pseudospherical viral capsids, built up from hundreds of identical proteins, constitute typical examples of the complexity attained by biological self-assembly. Chemical versions of the so-called 5 Platonic regular or 13 Archimedean semi-regular polyhedra are usually assembled combining molecular platforms with metals with commensurate coordination spheres. Here we report novel, self-assembled cages, using the conical-shaped carboxylic acid derivatives of calix[4]arene and calix[5]arene as ligands, and the uranyl cation UO22+ as a metallic counterpart, which coordinates with three carboxylates at the equatorial plane, giving rise to hexagonal bipyramidal architectures. As a result, octahedral and icosahedral anionic metallocages of nanoscopic dimensions are formed with an unusually small number of components. PMID:22510690

  5. Pilot scale for preparation of ammonium uranyl carbonate

    International Nuclear Information System (INIS)

    Santos, L.R. dos.

    1989-01-01

    The procedure adopted for obtaining Ammonium Uranyl Carbonate (AUC) from uranium hexafluoride (UF sub(6)) or aqueous solutions of uranylnitrate (UO sub(2)(NO sub(3)) sub(2)) is described in the present work. This procedure involves the precipitation of AUC in a chemical reactor by the addition of gaseous UF sub(6) or solutions of uranylnitrate to NH sub(3) and CO sub(2) gases in a solution containing ammonium bicarbonate, where pH and temperature are controlled. Details regarding the characterization and quality control methods in the preparation of AUC are presented along with their physical and chemical properties. Some informations about effluents generated during the process are presented too. An attempt is made to correlate the parameters involved in the precipitation process of AUC and their characteristics. (author)

  6. Cutaneous contamination after a uranyl nitrate skin burn: incident report

    International Nuclear Information System (INIS)

    Berard, P.; Chalabreysse, J.; Quesne, B.; Auriol, B.

    1994-01-01

    The authors review the circumstances of a handburn incident by a mixture of dilute nitric acid and uranyl nitrate. The burn was localised on the thumb and three fingers of the left hand. After abundant washing, external direct measurements revealed the presence of uranium on the fingers. The injured employee was maintained under observation for ten days, and therapy was performed until all the activity disappeared. External monitoring with various detectors, and measurements of the bandages and skin showed a rapid decrease of uranium fixation. All urine was collected throughout the duration of the treatment. The study shows that all the activity was retained on the burnt skin, with very little systemic uptake. Rapid peeling eliminated the cutaneous retention. Internal and external dose assessments were calculated and the committed effective dose equivalent and the committed dose equivalent for the skin and bone surfaces were low. (author)

  7. Complex formation between uranyl and various thiosemicarbazide derivatives

    International Nuclear Information System (INIS)

    Chuguryan, D.G.; Dzyubenko, V.I.

    1987-01-01

    Complex formation between hexavalent uranium and salicylaldehyde thiosemicarbazone (H 2 L), salicylaldehyde S-methyl-isothiosemicarbazone (H 2 Q), S-methyl-N 1 ,N 4 -bis(salicylidene)isothiosemicarbazide(H 2 Z), and thiosemicarbazidodiacetic acid (H 2 R) has been studied spectrophotometrically in solution. Stability constants for complexes having the composition UO 2 A have been calculated. Solid uranyl derivatives having the composition UO 2 L x 2H 2 O, UO 2 Q x 2H 2 O, UO 2 Z x 2H 2 O, and UO 2 R x 2H 2 O have been obtained. These derivatives were isolated and their IR spectroscopic behavior and thermal properties were investigated

  8. Synthesized research report in the second mid-term research phase. Mizunami Underground Research Laboratory project, Horonobe Underground Research Laboratory project and geo-stability project

    International Nuclear Information System (INIS)

    Hama, Katsuhiro; Sasao, Eiji; Iwatsuki, Teruki; Saegusa, Hiromitsu; Sato, Toshinori; Umeda, Koji; Yasue, Kenichi; Asamori, Koichi; Osawa, Hideaki; Koide, Kaoru; Nagae, Isako; Natsuyama, Ryoko; Mizuno, Takashi; Fujita, Tomoo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Yokota, Hideharu; Ishii, Eiichi; Aoyagi, Kazuhei; Nakayama, Masashi; Ito, Hiroaki; Tsusaka, Kimikazu; Ohyama, Takuya; Senba, Takeshi; Amano, Kenji

    2015-08-01

    We have synthesised the research results from Mizunami/Horonobe URLs and geo-stability projects in the second mid-term research phase. It could be used as technical bases for NUMO/Regulator in each decision point from siting to beginning of disposal (Principal Investigation to Detailed Investigation Phase). High quality construction techniques and field investigation methods have been developed and implemented and these will be directly applicable to the National Disposal Program (along with general assessments of hazardous natural events and processes). It will be crucial to acquire technical knowledge on decisions of partial backfilling and final closure by actual field experiments in Mizunami/Horonobe URLs as main themes for the next phases. (author)

  9. Ligand exchange in uranyl complexes in non-aqueous solutions: equilibrium properties

    International Nuclear Information System (INIS)

    Egozy, Y.; Weiss, S.

    1976-01-01

    The systems uranyl nitrate, tributylphosphate and 8-hydroxyquinoline or diphenylcarbazone were studied in chloroform, carbon tetrachloride and 1,2-dichloroethane at a number of temperatures. The nature of the complexes formed was determined and the equilibrium constants and several thermodynamic functions were measured. 8-hydroxyquinoline and diphenylcarbazone will be valuable as indicators for uranyl in kinetic studies. They are also interesting since they participate, along with tributylphosphate, in formation of synergistic complexes. (author)

  10. Investigation of uranyl sorbed to Wyoming montmorillonite at amphoteric and exchange sites by optical spectroscopy

    International Nuclear Information System (INIS)

    Morris, D.E.; Chisholm-Brause, C.J.; Berg, J.M.; McKinley, J.P.; Zachara, J.M.; Smith, S.C.

    1993-01-01

    Using optical spectroscopy, the authors have characterized aqueous uranyl (UO 2 2+ ) sorption complexes on a sodium-saturated Wyoming montmorillonite (SWy-1) at low and high ionic strength (IS, as NaClO 4 . McKinley et al. (1193), ACS Spring Meeting) have shown that uranyl uptake is suppressed at high IS at these pH values, reflecting increased cation competition for exchange sites, and an increase in the ratio of uranyl species sorbed on amphoteric edge sites to those in exchange sites. At higher pH, sorption is less dependent on IS, with complexation by amphoteric edge sites becoming dominant as pH increases. At low pH, emission spectra for uranyl sorbed to SWy-1 from solutions with high IS ([Na]/[U] > 1000) are distinct from those at low IS ([Na]/[U] < 10). The low IS spectra are dominanted by a short lifetime component (τ∼0.5μs), and have low integrated intensities (normalized for uranium concentration). However, gated detection clearly resolves an additional, longer-loved component. The high IS spectra have significant contributions form 2-3 longer-lived components (5<τ120μs), and have much stronger intensities. Based on comparison to solution data, these results suggest that the uranyl moiety in the exchange sites is strikingly similar to the fully aquated uranyl monomer in solution, whereas the uranyl species occupying the edge sites are structurally more similar to hydrolyzed uranyl species in solution. At higher pH values, the emission spectra represent composites of at least the two distinct spectra identified at lower pH. However, the ratios of the different components and thus the overall emission spectra vary as a function of ionic strength. These results demonstrate that several spectroscopically (and therefore structurally) distinct sorption complexes exist in exchange and edges of SWy-1

  11. High-affinity uranyl-specific antibodies suitable for cellular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Reisser-Rubrecht, L.; Torne-Celer, C.; Renier, W.; Averseng, O.; Plantevin, S.; Quemeneur, E.; Bellanger, L.; Vidaud, C. [CEA Valrho, DSV, IBEB, Serv Biochim et Toxicol Nucl, F-30207 Bagnols Sur Ceze (France)

    2008-07-01

    Monoclonal antibodies (mAbs) have proved to be valuable models for the study of protein-metal interactions, and previous reports have described very specific antibodies to chelated metal ions, including uranyl. We raised specific mAbs against UO{sub 2}{sup 2+}-DCP-BSA (DCP, 1, 10-phenanthroline-2,9-dicarboxylic acid) to generate new sets of antibodies that might cross-react with various complexed forms of uranyl in different environments for further application in the field of toxicology. Using counter-screening with UO{sub 2}{sup 2+}-DCP-casein, we selected two highly specific mAbs against uranyl-DCP (K{sub D} = 10-100 pM): U04S and U08S. Competitive assays in the presence of different metal ions (UO{sub 2}{sup 2+}, Fe{sup 3+}, Zn{sup 2+}, Cu{sup 2+}, and Ca{sup 2+}) showed that uranyl in solution can act as a good competitor, suggesting some antibody ability to cross-react with chelating groups other than DCP in the UO{sub 2}{sup 2+} equatorial coordination plane. Interestingly, one of the antibodies could be used for revealing uranyl cations in cell samples. Fluorescence activated cell sorting analyses after immuno-labeling revealed the interaction of uranyl with human kidney cells HK2. The intracellular accumulation of uranyl could be directly visualized by metal-immunostaining using fluorescent-labeled mAb. Our results suggest that U04S mAb epitopes mostly include the uranyl fraction and its para-topes can accommodate a wide variety of chelating groups. (authors)

  12. Nephrotoxicity of uranyl acetate: effect on rat kidney brush border membrane vesicles

    International Nuclear Information System (INIS)

    Goldman, M.; Yaari, A.; Moran, A.; Doshnitzki, Z.; Cohen-Luria, R.

    2006-01-01

    Since the Gulf war exposure to depleted uranium, a known nephrotoxic agent, there is a renewed interest in the toxic effects of uranium in general and its mechanism of nephrotoxicity which is still largely unknown in particular. In order to investigate the mechanism responsible for uranium nephrotoxicity and the therapeutic effect of urine alkalization, we utilized rat renal brush border membrane vesicles (BBMV). Uranyl acetate (UA) caused a decrease in glucose transport in BBMV. The apparent K i of uranyl was 139±30 μg uranyl/mg protein of BBMV. Uranyl at 140 μg/mg protein of BBMV reduced the maximal capacity of the system to transport glucose [V max 2.2±0.2 and 0.96±0.16 nmol/mg protein for control and uranyl treated BBMV (P m (1.54±0.33 and 1.54±0.51 mM for control, and uranyl treated BBMV, respectively). This reduction in V max is at least partially due to a decrease in the number of sodium-coupled glucose transporters as apparent from the reduction in phlorizin binding to the uranyl treated membranes, V max was reduced from 247±13 pmol/mg protein in control BBMV to 119±3 pmol/mg protein in treated vesicles (P<0.001). The pH of the medium has a profound effect on the toxicity of UA on sodium-coupled glucose transport in BBMV: higher toxicity at neutral pH (around pH 7.0), and practically no toxicity at alkaline pH (7.6). This is the first report showing a direct inhibitory dose and pH dependent effect of uranyl on the glucose transport system in isolated apical membrane from kidney cortex. (orig.)

  13. High-affinity uranyl-specific antibodies suitable for cellular imaging

    International Nuclear Information System (INIS)

    Reisser-Rubrecht, L.; Torne-Celer, C.; Renier, W.; Averseng, O.; Plantevin, S.; Quemeneur, E.; Bellanger, L.; Vidaud, C.

    2008-01-01

    Monoclonal antibodies (mAbs) have proved to be valuable models for the study of protein-metal interactions, and previous reports have described very specific antibodies to chelated metal ions, including uranyl. We raised specific mAbs against UO 2 2+ -DCP-BSA (DCP, 1, 10-phenanthroline-2,9-dicarboxylic acid) to generate new sets of antibodies that might cross-react with various complexed forms of uranyl in different environments for further application in the field of toxicology. Using counter-screening with UO 2 2+ -DCP-casein, we selected two highly specific mAbs against uranyl-DCP (K D = 10-100 pM): U04S and U08S. Competitive assays in the presence of different metal ions (UO 2 2+ , Fe 3+ , Zn 2+ , Cu 2+ , and Ca 2+ ) showed that uranyl in solution can act as a good competitor, suggesting some antibody ability to cross-react with chelating groups other than DCP in the UO 2 2+ equatorial coordination plane. Interestingly, one of the antibodies could be used for revealing uranyl cations in cell samples. Fluorescence activated cell sorting analyses after immuno-labeling revealed the interaction of uranyl with human kidney cells HK2. The intracellular accumulation of uranyl could be directly visualized by metal-immunostaining using fluorescent-labeled mAb. Our results suggest that U04S mAb epitopes mostly include the uranyl fraction and its para-topes can accommodate a wide variety of chelating groups. (authors)

  14. A study of precipitation from pure solutions of uranyl nitrate; Etude de la precipitaion de solutions pures de nitrate d'uranyle

    Energy Technology Data Exchange (ETDEWEB)

    Decrop, J; Holder, J; Sauteron, J [Commissariat a l' Energie Atomique, Usine du Bouchet, Service des Lab. de Recherches et de Controle, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    After its purification by extraction of the uranyl nitrate from the organic solvent, uranium has to be converted into solid form again: uranium trioxide (UO{sub 3}). It can be done either by thermal decomposition of uranyl nitrate or by precipitation of uranium, followed by filtration and calcination. Only the second method has been studied for now at the Bouchet plant. This paper reports the bench-scale and pilot-scale experiments of the studies of the precipitation of pure solutions of uranyl nitrate using ammonia (gaseous or in solution) or ammonium carbonate. These have been carried out at the Bouchet plant. It investigates the chemical aspect (pH, precipitates chemical composition) and the technical aspect of the different ways of precipitation (conditions of precipitation, decantation and filtration of precipitates). (M.P.)

  15. Functional polyterthiophene-appended uranyl-salophen complex: Electropolymerization and ion-selective response for monohydrogen phosphate

    International Nuclear Information System (INIS)

    Kim, Junghwan; Kang, Dong Min; Shin, Sung Chul; Choi, Myong Yong; Kim, Jineun; Lee, Shim Sung; Kim, Jae Sang

    2008-01-01

    We have synthesized a bis(terthiophene)-appended uranyl-salophen complex, comprising N,N'-bis[4-(5,2':5',2''-terthiophen-3'-yl)salicylidene] -1,2-ethanediamine-uranyl complexes (TUS), and used it as a monomer for the electrochemical polymerizations (poly-TUS) on glassy carbon surfaces to prepare functionalized conducting polymer (CP) films. The poly-TUS films prepared from propylene carbonate/0.1 M tetrabutyl ammonium perchlorate (TBAP) on a glassy carbon electrode have both the functionality of ion-to-electron transducers (solid contact) and Lewis-acidic binding sites for a monohydrogen phosphate (MHP) ion-selective electrode (ISE). The CP/poly-TUS sensor showed a linear range between 1.0 x 10 -1 and 1.0 x 10 -4.5 M with a near-Nernstian behavior (-30.4 mV decade -1 ) at a pH of 8.2. The detection limit of the electrode was 10 -5.0 M and the response time was improved (<10 s) compared to that of conventional ISEs (<20 s). For comparison, a conventional ISE (with an internal aqueous solution) based on a TUS monomer/o-nitrophenyl octylether (o-NPOE)/polyvinyl chloride (PVC) liquid membrane with or without tridodecylmethylammonium chloride (TDMACl) as an additive was also constructed and its performance as an MHP-ISE were studied. The superior selectivity and sensitivity of the CP/poly-TUS sensor enabled the direct measurement of MHP in a wide variety of applications

  16. Observation of phase noise reduction in photonically synthesized sub-THz signals using a passively mode-locked laser diode and highly selective optical filtering

    DEFF Research Database (Denmark)

    Criado, A. R.; Acedo, P.; Carpintero, G.

    2012-01-01

    A Continuous Wave (CW) sub-THz photonic synthesis setup based on a single Passively Mode-Locked Laser Diode (PMLLD) acting as a monolithic Optical Frequency Comb Generator (OFCG) and highly selective optical filtering has been implemented to evaluate the phase noise performance of the generated sub...

  17. Phase Evolution and Mechanical Properties of AlCoCrFeNiSi x High-Entropy Alloys Synthesized by Mechanical Alloying and Spark Plasma Sintering

    Science.gov (United States)

    Kumar, Anil; Swarnakar, Akhilesh Kumar; Chopkar, Manoj

    2018-05-01

    In the current investigation, AlCoCrFeNiSi x (x = 0, 0.3, 0.6 and 0.9 in atomic ratio) high-entropy alloy systems are prepared by mechanical alloying and subsequently consolidated by spark plasma sintering. The microstructural and mechanical properties were analyzed to understand the effect of Si addition in AlCoCrFeNi alloy. The x-ray diffraction analysis reveals the supersaturated solid solution of the body-centered cubic structure after 20 h of ball milling. However, the consolidation promotes the transformation of body-centered phases partially into the face-centered cubic structure and sigma phases. A recently proposed geometric model based on the atomic stress theory has been extended for the first time to classify single phase and multi-phases on the high-entropy alloys prepared by mechanical alloying and spark plasma sintering process. Improved microhardness and better wear resistance were achieved as the Si content increased from 0 to 0.9 in the present high-entropy alloy.

  18. Temperature and pH driven association in uranyl aqueous solutions

    Directory of Open Access Journals (Sweden)

    M. Druchok

    2012-12-01

    Full Text Available An association behavior of uranyl ions in aqueous solutions is explored. For this purpose a set of all-atom molecular dynamics simulations is performed. During the simulation, the fractions of uranyl ions involved in dimer and trimer formations were monitored. To accompany the fraction statistics one also collected distributions characterizing average times of the dimer and trimer associates. Two factors effecting the uranyl association were considered: temperature and pH. As one can expect, an increase of the temperature decreases an uranyl capability of forming the associates, thus lowering bound fractions/times and vice versa. The effect of pH was modeled by adding H+ or OH- ions to a "neutral" solution. The addition of hydroxide ions OH- favors the formation of the associates, thus increasing bound times and fractions. The extra H+ ions in a solution produce an opposite effect, thus lowering the uranyl association capability. We also made a structural analysis for all the observed associates to reveal the mutual orientation of the uranyl ions.

  19. Aggregation-induced emission active tetraphenylethene-based sensor for uranyl ion detection

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Jun; Huang, Zeng; Hu, Sheng [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, Sichuan Province (China); Li, Shuo, E-mail: lishuo@cqut.edu.cn [School of Chemical Engineering, Chongqing University of Technology, Chongqing 400054 (China); Li, Weiyi, E-mail: weiyili@mail.xhu.edu.cn [School of Science, Xihua University, Chengdu, Sichuan, 610065 (China); Wang, Xiaolin, E-mail: xlwang@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, Sichuan Province (China)

    2016-11-15

    Highlights: • A novel AIE fluorescent sensor for the detection of uranyl has been developed. • TPE-T is capable of visually distinguish UO{sub 2}{sup 2+} among many metals owing to the AIE phenomenon. • TPE-T showed a wide effective pH range, high selectivity and good anti-interference qualities. • TPE-T showed good accuracy in the determination of uranyl in river water. - Abstract: A novel tetraphenylethene-based fluorescent sensor, TPE-T, was developed for the detection of uranyl ions. The selective binding of TPE-T to uranyl ions resulted in a detectable signal owing to the quenching of its aggregation-induced emission. The developed sensor could be used to visually distinguish UO{sub 2}{sup 2+} from lanthanides, transition metals, and alkali metals under UV light; the presence of other metal ions did not interfere with the detection of uranyl ions. In addition, TPE-T was successfully used for the detection of uranyl ions in river water, illustrating its potential applications in environmental systems.

  20. Theoretical insights into the uranyl adsorption behavior on vanadium carbide MXene

    Science.gov (United States)

    Zhang, Yu-Juan; Zhou, Zhang-Jian; Lan, Jian-Hui; Ge, Chang-Chun; Chai, Zhi-Fang; Zhang, Peihong; Shi, Wei-Qun

    2017-12-01

    Remediation of the contamination by long-lived actinide wastes is extremely important but also challenging. Adsorption based techniques have attracted much research attention for their potential as low-cost and effective methods to reduce the radioactive waste from solution. In this work, we have investigated the adsorption behavior of uranyl species [with the general form UO2(L1)x(L2)y(L3)z, where L1, L2 and L3 stand for ligands H2O, OH and CO3, respectively] on hydroxylated vanadium carbide V2C(OH)2 MXene nanosheets using density functional theory based simulation methods We find that all studied uranyl species can stably bond to hydroxylated MXene with binding energies ranging from -3.3 to -4.6 eV, suggesting that MXenes could be effective adsorbers for uranyl ions. The strong adsorption is achieved by forming two Usbnd O bonds with the hydroxylated Mxene. In addition, the axial oxygen atoms from the uranyl ions form hydrogen bonds with the hydroxylated V2C, further strengthening the adsorption. We have also investigated the effects of F termination on the uranyl adsorption properties of V2C nanosheets. Usbnd F bonds are in general weaker than Usbnd O bonds on the adsorption site, suggesting that F terminated Mexne is less favorable for uranyl adsorption applications.

  1. Raman spectral titration method: an informative technique for studying the complexation of uranyl with uranyl(vi)-DPA/oxalate systems as examples.

    Science.gov (United States)

    Liu, Qian; Zhang, Qianci; Yang, Suliang; Zhu, Haiqiao; Liu, Quanwei; Tian, Guoxin

    2017-10-10

    The Raman band at about 870 cm -1 originating from the symmetric stretch vibration (ν 1 ) of uranyl, UO 2 2+ , has proven to be very informative for investigating the complexation of uranyl using perchlorate or nitrate of known concentration as internal standards. The concentration of uranyl can be conveniently calculated by using the ratio of the directly read band intensities of uranyl and the added reference, ClO 4 - , with a factor of 1.72. While with NO 3 - of concentration lower than 1.8 M as the reference, a factor of 0.85 should be used. Furthermore, with added internal standards, the linear relationship between the Raman intensity and the concentration of the corresponding species is illustrated by the spectral titration of U(vi) with a very strong ligand, dipicolinic acid (DPA); and the application of a spectral titration method with Raman spectroscopy in studying the complexation of uranyl is demonstrated by the titration of U(vi) with oxalate. The stepwise changes in the Raman shift of 18, 17, and 6 cm -1 , corresponding to the three oxalate anions successively bonding to UO 2 2+ , imply that the coordination modes are different. In the 1 : 1 and 1 : 2 ratios of metal to ligand complexes, the oxalate anions bond to the uranyl ion in side-on bidentate mode, but in the 1 : 3 complex the third oxalate bonds in head-on mode, which is much weaker than the first two.

  2. Contribution to the study of uranyl salts in butyl phosphate solutions; Contribution a l'etude des solutions de sels d'uranyle dans les phosphates butyliques

    Energy Technology Data Exchange (ETDEWEB)

    Coulon, A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1965-06-01

    A spectroscopic study in the normal infrared region and involving the following associations: tri-alkyl phosphates (tri-butyl, tri-ethyl, tri-methyl), uranyl salts (nitrate, chloride, acetate) has confirmed the existence of an interaction between the phosphoryl group and the uranium atom, as shown by a movement of absorption band for the valency P = 0 from {approx} 1270 cm{sup -1} to {approx} 1180 cm{sup -1}. A study of the preparation, analysis and spectroscopy of the solids obtained by the precipitation of uranyl salts by acid butyl phosphates has been carried out. By infrared spectrophotometry it has been shown that the tri-butyl and di-butyl phosphates are associated in non-polar diluents even before the uranium is introduced. The extraction of uranyl salts from acid aqueous solutions by a diluted mixture of tri-butyl and di-butyl phosphates proceeds by different mechanisms according to the nature of the ion (nitrate or chloride). (author) [French] Une etude spectroscopique dans l'infrarouge moyen portant sur les associations: - phosphates trialcoyliques (tributylique - triethylique - trimethylique) - sels d'uranyle (nitrate, chlorure, acetate) a confirme l'existence d'une interaction entre le groupement phosphoryle et l'atome d'uranium, se manifestant par un deplacement de la bande d'absorption de la vibration de valence P = 0 de {approx} 1270 cm{sup -1} a {approx} 1180 cm{sup -1}. Une etude preparative, analytique et spectroscopique des solides obtenus par precipitation de sels d'uranyle par les phosphates butyliques acides a ete effectuee. La spectrophotomerie infrarouge met en evidence l'association, anterieure a toute introduction d'uranium, des phosphates tributylique et dibutylique dans des diluants non polaires. L'extraction de sels d'uranyle, d'une solution aqueuse acide par un melange dilue de phosphates tributylique et dibutylique, s'effectue suivant des processus differents a la nature de l'anion (nitrate ou chlorure). (auteur)

  3. Thermolysis synthesis of pure phase NiO from novel sonochemical synthesized Ni(II) nano metal-organic supramolecular architecture.

    Science.gov (United States)

    Hanifehpour, Younes; Morsali, Ali; Mirtamizdoust, Babak; Joo, Sang Woo; Soltani, Behzad

    2017-07-01

    Nano-structures of a new supramolecular coordination compound of divalent nickel with the pyrazol (pzH) containing the terminal azide anions, [Ni(pzH) 2 (N 3 ) 2 ] (1), with discrete molecular architecture (DMA) in solid state was synthesized via sonochemical method. The new nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction, IR, and elemental analysis. Compound 1 was structurally characterized by single crystal X-ray diffraction and the single-crystal X-ray data shows that the coordination number of Ni (II) ions is six, (NiN 6 ), with four N-donor atoms from neutral "pzH" ligands and two N-donors from two terminal azide anions. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The structure of the title complex was optimized by density functional theory calculations. Calculated structural parameters and IR spectra for the title complex are consistent with the crystal structure. The NiO nanoparticles were obtained by thermolysis of 1 at 180°C with oleic acid as a surfactant. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Stoichiometry of the U3O8 phase formed during calcination of some uranium compounds

    International Nuclear Information System (INIS)

    El-Fekey, S.A.; Farah, M.Y.; Rofail, N.H.

    1981-01-01

    Although recent work has shown U 3 O 8 phase to be the decomposition product obtained after calcining uranyl nitrate, sulphate or ammonium uranate, neither the necessary conditions for obtaining stoichiometric U 3 O 8 nor the details of the reaction have been established. Presence of sulphate or nitrate ions during preparation greatly affects the O/U of the obtained oxides and the physico-chemical properties of uranium tetrafluoride prepared afterwards from it (1-3). The aim of the present investigation was to study the effect of calcination regimes on the stoichiometry of the U 3 O 8 phase produced by the thermal decomposition of uranyl nitrate, sulphate, and ammonium uranate, which was prepared by precipitation from nuclear-pure uranyl sulphate. Stoichiometry of the U 3 O 8 phase formed during calcination of ammonium uranate precipitated from nuclear pure uranyl nitrate solution was reported before (1)

  5. Reduction of uranyl carbonate and hydroxyl complexes and neptunyl carbonate complexes studied with chemical-electrochemical methods and rixs spectroscopy

    International Nuclear Information System (INIS)

    Butorin, Sergei; Nordgren, Joseph; Ollila, Kaija; Albinsson, Yngve; Werme, Lars

    2003-10-01

    Sweden and Finland plan to dispose of spent fuel from commercial nuclear power plants in deep underground repositories sited in granitic rocks. The fuel assemblies will be placed in canisters consisting of an outer corrosion-resistant copper shell with an inner cast iron insert that gives mechanical strength and reduces void space in the canister. The canister will be placed in a disposal borehole lined with compacted bentonite blocks. After sealing of the borehole, groundwater seepage will saturate the bentonite. The water flow path and transport mechanism between the host rock and the canister will be via diffusion through the swollen bentonite. Any oxygen trapped in the repository will be consumed by reaction with the host rock, pyrite in the bentonite and through microbial activity, giving long-term conditions with low redox potentials. Under these conditions, uranium dioxide - the matrix of unirradiated fuel - is a stable phase. This reducing near-field environment can upset by radiolysis of water caused by the radioactivity of the fuel, which after a few hundred years will be primarily alpha activity. Radiolysis of water produces equal amounts of oxidising and reducing species, but the reducing species produced by alpha radiolysis is molecular hydrogen, which is expected to be far less reactive than the produced oxidising species, H 2 O 2 . Alpha radiolysis could create locally oxidising conditions close to the fuel surface and oxidise the U(IV) in the uranium dioxide fuel to the more soluble U(VI) oxidation state. Furthermore, the solubility of U(VI) is enhanced in the presence of bicarbonate/carbonate by the formation of strong anionic uranyl carbonate complexes. This increase in solubility can amount to 4 to 5 orders of magnitude depending on the composition of the groundwater in contact with the fuel. The other tetravalent actinides in the fuel, Np and Pu, also have higher solubilities when oxidised beyond 4 + to neptunyl and plutonyl species. Once these

  6. Influence of uranyl speciation and iron oxides on uranium biogeochemical redox reactions

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, B.D.; Amos, R.T.; Nico, P.S.; Fendorf, S.

    2010-03-15

    Uranium is a pollutant of concern to both human and ecosystem health. Uranium's redox state often dictates its partitioning between the aqueous- and solid-phases, and thus controls its dissolved concentration and, coupled with groundwater flow, its migration within the environment. In anaerobic environments, the more oxidized and mobile form of uranium (UO{sub 2}{sup 2+} and associated species) may be reduced, directly or indirectly, by microorganisms to U(IV) with subsequent precipitation of UO{sub 2}. However, various factors within soils and sediments may limit biological reduction of U(VI), inclusive of alterations in U(VI) speciation and competitive electron acceptors. Here we elucidate the impact of U(VI) speciation on the extent and rate of reduction with specific emphasis on speciation changes induced by dissolved Ca, and we examine the impact of Fe(III) (hydr)oxides (ferrihydrite, goethite and hematite) varying in free energies of formation on U reduction. The amount of uranium removed from solution during 100 h of incubation with S. putrefaciens was 77% with no Ca or ferrihydrite present but only 24% (with ferrihydrite) and 14% (no ferrihydrite) were removed for systems with 0.8 mM Ca. Imparting an important criterion on uranium reduction, goethite and hematite decrease the dissolved concentration of calcium through adsorption and thus tend to diminish the effect of calcium on uranium reduction. Dissimilatory reduction of Fe(III) and U(VI) can proceed through different enzyme pathways, even within a single organism, thus providing a potential second means by which Fe(III) bearing minerals may impact U(VI) reduction. We quantify rate coefficients for simultaneous dissimilatory reduction of Fe(III) and U(VI) in systems varying in Ca concentration (0 to 0.8 mM), and using a mathematical construct implemented with the reactive transport code MIN3P, we reveal the predominant influence of uranyl speciation, specifically the formation of uranyl

  7. Sorption of strontium on uranyl peroxide: implications for a high-level nuclear waste repository.

    Science.gov (United States)

    Sureda, Rosa; Martínez-Lladó, Xavier; Rovira, Miquel; de Pablo, Joan; Casas, Ignasi; Giménez, Javier

    2010-09-15

    Strontium-90 is considered the most important radioactive isotope in the environment and one of the most frequently occurring radionuclides in groundwaters at nuclear facilities. The uranyl peroxide studtite (UO2O2 . 4H2O) has been observed to be formed in spent nuclear fuel leaching experiments and seems to have a relatively high sorption capacity for some radionuclides. In this work, the sorption of strontium onto studtite is studied as a function of time, strontium concentration in solution and pH. The main results obtained are (a) sorption is relatively fast although slower than for cesium; (b) strontium seems to be sorbed via a monolayer coverage of the studtite surface, (c) sorption has a strong dependence on ionic strength, is negligible at acidic pH, and increases at neutral to alkaline pH (almost 100% of the strontium in solution is sorbed above pH 10). These results point to uranium secondary solid phase formation on the spent nuclear fuel as an important mechanism for strontium retention in a high-level nuclear waste repository (HLNW). Copyright 2010 Elsevier B.V. All rights reserved.

  8. Improvement of the cloud point extraction of uranyl ions by the addition of ionic liquids.

    Science.gov (United States)

    Gao, Song; Sun, Taoxiang; Chen, Qingde; Shen, Xinghai

    2013-12-15

    The cloud point extraction (CPE) of uranyl ions by different kinds of extractants in Triton X-114 (TX-114) micellar solution was investigated upon the addition of ionic liquids (ILs) with various anions, i.e., bromide (Br(-)), tetrafluoroborate (BF4(-)), hexafluorophosphate (PF6(-)) and bis[(trifluoromethyl)sulfonyl]imide (NTf2(-)). A significant increase of the extraction efficiency was found on the addition of NTf2(-) based ILs when using neutral extractant tri-octylphosphine oxide (TOPO), and the extraction efficiency kept high at both nearly neutral and high acidity. However, the CPE with acidic extractants, e.g., bis(2-ethylhexyl) phosphoric acid (HDEHP) and 8-hydroxyquinoline (8-HQ) which are only effective at nearly neutral condition, was not improved by ILs. The results of zeta potential and (19)F NMR measurements indicated that the anion NTf2(-) penetrated into the TX-114 micelles and was enriched in the surfactant-rich phase during the CPE process. Meanwhile, NTf2(-) may act as a counterion in the CPE of UO2(2+) by TOPO. Furthermore, the addition of IL increased the separation factor of UO2(2+) and La(3+), which implied that in the micelle TOPO, NTf2(-) and NO3(-) established a soft template for UO2(2+). Therefore, the combination of CPE and IL provided a supramolecular recognition to concentrate UO2(2+) efficiently and selectively. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Development of processes for pilot plant production of purified uranyl nitrate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Alfredson, P. G.; Charlton, B. G.; Ryan, R. K.; Vilkaitis, V. K.

    1975-01-15

    Nuclear purity uranyl nitrate solutions were produced from Rum Jungle yellow cake by dissolution in nitric acid and purification by solvent extraction with 20 vol. per cent tributyl phosphate in kerosene using pump - mix mixer-settler contactors. The design of the equipment, experimental studies and operating experience are described. Dissolution of yellow cake and recycled uranium oxide materials was readily carried out in a 100 l dissolver to give solutions containing 300 gU l{sup -1} and 0.5 to 4 M nitric acid. Filtration of silica from this solution prior to solvent extraction was not necessary in this work for yellow cake containing 0.25 per cent silica. A low acid flowsheet for uranium purification was developed in which the nitric acid consumption was reduced by 76 per cent and the throughput of the mixer-settler units was increased by 67 per cent compared with the initial design flowsheet. Nine extraction and seven scrubbing stages were used with a feed solution containing 300 gU l{sup -1} and 1.0 M nitric acid and with a portion of the product recycled as scrub solution. The loaded organic phase was stripped in 16 stages with 0.05 M nitric acid heated to 60 deg C to give a 120 gU l{sup -1} product. The uranium concentration in the raffinate was < 0.04 g l{sup -1}, corresponding to approximately 0.01 per cent of the feed. (author)

  10. Uranium (VI) chemistry at the interface solution/minerals (quartz and aluminium hydroxide): experiments and spectroscopic investigations of the uranyl surface species

    International Nuclear Information System (INIS)

    Froideval, A.

    2004-09-01

    This study deals with the understanding of the uranyl chemistry at the 0.1 M NaNO 3 solution/mineral (quartz and aluminium hydroxide) interface. The aims are:(i) to identify and to characterize the different uranyl surface species (mononuclear, polynuclear complexes and/or precipitates...), i.e. the coordination environments of sorbed/precipitated uranyl ions, by using X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS) and time-resolved laser-induced fluorescence spectroscopy (TRLFS), and;(ii) to investigate the influence of pH, initial uranyl aqueous concentration and hydroxyl ligand concentration on the uranyl surface speciation. Our study on the speciation of uranyl ions at the quartz surface (i) confirms the formation of uranyl polynuclear/oligomers on quartz from moderate (1 μmol/m 2 ) to high (26 μmol/m 2 ) uranyl surface concentrations and (ii) show that theses polynuclear species coexist with uranyl mononuclear surface species over a pH range ≅ 5-8.5 and a wide range of initial uranyl concentration o f the solutions (10-100 μM). The uranyl concentration of these surface species depends on pH and on the initial uranyl aqueous concentration. Hydrate (surface-) precipitates and/or adsorbed polynuclear species and monomeric uranyl surface complexes are formed on aluminium hydroxide. Uranyl mononuclear complexes are predominant at acidic pH, as well as uranyl in solution or on the surface. Besides mononuclear species, precipitates and/or adsorbed polynuclear species are predominantly formed at neutral pH values on aluminium hydroxide. A main contribution of our investigations is that precipitation and/or adsorption of polynuclear species seem to occur at low uranyl surface concentrations (0.01-0.4 μmol/m 2 ). The uranyl surface speciation is mainly dependent on the pH and the aluminol ligand concentration. (author)

  11. Contribution to the study of the mechanism of extraction of uranyl chloride by long chain aliphatic amines; Contribution a l'etude du mecanisme d'extraction du chlorure d'uranyle par les amines aliphatiques a longues chaines

    Energy Technology Data Exchange (ETDEWEB)

    Rubinstein, G.R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    After having studied and developed the mechanisms which may 'a priori' explain the extraction process (co-ordination, ion association or intermediate mechanism), experience shows that ion association only should be taken into consideration. The structure of the organic complex of uranyl chloride has been defined on the basis of the study of the variation of the distribution coefficient of uranium between the two phases at the equilibrium as a function of successively the activity of Cl{sup -} ions in the aqueous phase, the concentration of amine salt in the organic phase and finally of the concentration of uranium in the aqueous phase. The plotting of the results in bi-logarithmic co-ordinates enables us to propose the following formula for the extracted compound: UO{sub 2}Cl{sub 4}{sup --}(NR{sub 3}H{sup +}){sub 2}. The calculation of the equilibrium constant of formation of the organic compound of uranyl chloride has been possible in the case of diluted solutions of uranium only. (author) [French] Apres avoir expose et developpe les mecanismes qui a priori pouvaient expliquer le processus d'extraction (coordination, association d'ions ou mecanisme intermediaire), le recours a l'experience a finalement permis de ne retenir que l'association d'ions. La structure du complexe organique de chlorure d'uranyle a ete definie a partir de l'etude de la variation du coefficient de partage de l'uranium entre les deux phases a l'equilibre en fonction successivement de l'activite des ions Cl{sup -} en phase aqueuse, de la concentration de sel d'amine en phase organique et enfin de la concentration d'uranium de la phase aqueuse. La representation bilogarithmique des resultats de ces essais a permis de proposer la formule suivante pour le compose extrait: UO{sub 2}Cl{sub 4}{sup --}(NR{sub 3}H{sup +}){sub 2}. Le calcul de la constante d'equilibre de formation du compose organique de chlorure d'uranyle

  12. Phase formation, morphology and magnetic properties of MgFe{sub 2}O{sub 4} nanoparticles synthesized by hydrothermal technique

    Energy Technology Data Exchange (ETDEWEB)

    Nonkumwong, Jeeranan [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Ananta, Supon [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Jantaratana, Pongsakorn [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 11900 (Thailand); Phumying, Santi; Maensiri, Santi [Advanced Materials Physics Laboratory (Amp.), School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Srisombat, Laongnuan, E-mail: slaongnuan@yahoo.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-05-01

    In the present work, the processing conditions for obtaining monodispersed magnesium ferrite (MgFe{sub 2}O{sub 4}) nanoparticles with the desired morphology and relatively high saturation magnetization via hydrothermal technique were developed. For the first time, the effects of base type and reaction conditions (i.e. temperature and time) on phase formation, morphology and magnetic properties of the obtained products were determined by using a combination of XRD, TEM/EDX and VSM techniques. It is seen that the saturation magnetization of the particles can be increased by employing lower reaction temperature and/or shorter reaction time, while narrow size distribution of the particles can be maintained. In addition, it was found that pure phase of superparamagnetic MgFe{sub 2}O{sub 4} nanoparticles with the smallest size of about 65 nm was obtained by using CH{sub 3}COONa as a base at 180 °C for 14 h. - Highlights: • Preparation of MgFe{sub 2}O{sub 4} nanoparticles by hydrothermal method. • Effects of base and reaction conditions on formation and morphology MgFe{sub 2}O{sub 4} particles. • Producing the 65 nm MgFe{sub 2}O{sub 4} nanoparticles with superparamagnetic property.

  13. Charge-density matching in organic-inorganic uranyl compounds

    Energy Technology Data Exchange (ETDEWEB)

    Krivovichev, S.V. [Saint Petersburg State Univ., Dept. of Crystallography, Faculty of Geology (Russian Federation); Krivovichev, S.V.; Tananaev, I.G.; Myasoedov, B.F. [Russian Academy of Sciences, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Moscow (Russian Federation)

    2007-10-15

    Single crystals of [C{sub 10}H{sub 26}N{sub 2}][(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)](H{sub 2}SeO{sub 4}){sub 0.85}(H{sub 2}O){sub 2} (1), [C{sub 10}H{sub 26}N{sub 2}][(UO{sub 2})(SeO{sub 4}){sub 2}] (H{sub 2}SeO{sub 4}){sub 0.50}(H{sub 2}O) (2), and [C{sub 8}H{sub 20}N]{sub 2}[(UO{sub 2})(SeO{sub 4}){sub 2}(H{sub 2}O)] (H{sub 2}O) (3) were prepared by evaporation from aqueous solution of uranyl nitrate, selenic acid and the respective amines. The structures of the compounds have been solved by direct methods and structural models have been obtained. The structures of the compounds 1, 2, and 3 contain U and Se atoms in pentagonal bipyramidal and tetrahedral coordinations, respectively. The UO{sub 7} and SeO{sub 4} polyhedra polymerize by sharing common O atoms to form chains (compound 1) or sheets (compounds 2 and 3). In the structure of 1, the layers consisting of hydrogen-bonded [UO{sub 2}(SeO{sub 4}){sub 2}(H{sub 2}O)]{sup 2-} chains are separated by mixed organic-inorganic layers comprising from [NH{sub 3}(CH{sub 2}){sub 10}NH{sub 3}]{sup 2+} molecules, H{sub 2}O molecules, and disordered electroneutral (H{sub 2}SeO{sub 4}) groups. The structure of 2 has a similar architecture but a purely inorganic layer is represented by a fully connected [UO{sub 2}(SeO{sub 4}){sub 2}]{sup 2-} sheet. The structure of 3 does not contain disordered (H{sub 2}SeO{sub 4}) groups but is based upon alternating [UO{sub 2}(SeO{sub 4}){sub 2}(H{sub 2}O)]{sup 2-} sheets and 1.5-nm-thick organic blocks consisting of positively charged protonated octylamine molecules, [NH{sub 3}(CH{sub 2}){sub 7}CH{sub 3}]{sup +}. The structures may be considered as composed of anionic inorganic sheets (2D blocks) and cationic organic blocks self-organized according to competing hydrophilic-hydrophobic interactions. Analysis of the structures allows us to conclude that the charge-density matching principle is observed in uranyl compounds. In order to satisfy some basic peculiarities of uranyl (in

  14. Sorption of uranyl species on zircon and zirconia

    International Nuclear Information System (INIS)

    Lomenech, C.; Drot, R.; Simoni, E.; Ehrhardt, J.J.; Mielczarski, J.

    2002-01-01

    The safety of a long-term storage of radioactive waste in deep geological repositories would be strongly affected by the migration properties of radionuclides through the different barriers to the surface of the earth. Since the main process involved in the retention of radioactive ions is their sorption at the water/ mineral interface, a quantitative description of the sorption reactions is needed. Macroscopic data have for a long time been the only source of information used to propose a modelling of sorption equilibria, although they bring no direct information on the nature of the sorbed species; a microscopic structural investigation of the surface complexes is difficult indeed, because of the small amount of matter sorbed. Thus, in this study, parallel to the macroscopic measurements, different complementary spectroscopic techniques have been used in order to determine the nature of the surface species. As the final purpose of such a study is the simulation of the experimental retention data, the precise structural identification of the sorption equilibria will then be very useful to constrain the data simulation code. In this work, we present the results of both macroscopic and microscopic studies of the sorption of uranyl species on zircon and zirconia. The first part of our macroscopic approach was the surface characterisation of the non-sorbed materials by the determination of the specific areas, of the pH of the isoelectric points, and of the sorption site numbers, while the second part aimed at obtaining the sorption isotherms (percentage of sorption versus pH), which was performed using alpha spectrometry, for different uranyl concentrations, media (NaClO 4 or KNO 3 ) and ionic strengths. The spectroscopic identification of the different surface complexes and sorption sites has been carried out using four different spectroscopies. Whereas tune-resolved laser spectro-fluorimetry gave a direct answer concerning the number of surface species (only for a

  15. Optical and Dielectric Properties of CuAl2O4 Films Synthesized by Solid-Phase Epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Leu, L. C. [University of Florida, Gainesville; Norton, David P. [University of Florida; Jellison Jr, Gerald Earle [ORNL; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York; Xiong, X. [SuperPower Incorporated, Schenectady, New York

    2007-01-01

    The synthesis and properties of CuAl{sub 2}O{sub 4} thin films have been examined. The CuAl{sub 2}O{sub 4} films were deposited via reactive direct current magnetron sputter using a CuAl{sub 2} target. As-deposited films were amorphous. Post-deposition annealing at high temperature in oxygen yielded solid-phase epitaxy on MgO. The film orientation was cube-on-cube epitaxy on (001) MgO single-crystal substrates. The films were transparent to visible light. The band gap of crystalline CuAl{sub 2}O{sub 4} was determined to be {approx} 4 eV using a Tauc plot from the optical transmission spectrum. The dielectric constant of the amorphous films was determined to be {approx} 20-23 at 1-100 kHz.

  16. 1H chemically induced dynamic nuclear polarization in the photodecomposition of uranyl carboxylates

    International Nuclear Information System (INIS)

    Rykov, S.V.; Khudyakov, I.V.; Skakovsky, E.D.; Burrows, H.D.; Formosinho, S.J.; Miguel, M. da G.M.

    1991-01-01

    Chemically induced dynamic nuclear polarization ( 1 H CIDNP) has been observed during photolysis of uranyl salts of pivalic, propionic, and acetic acids in D 2 O solution, [ 2 H 6 ]acetone, [ 2 H 4 ]methanol, or in some other solvent. The multiplet polarization of isobutene and isobutane protons has been found under photolysis of deoxygenated pivalate solution. The polarized compounds are formed in the triplet pairs of tert-butyl free radicals. 1 H Emission of the tert-butylperoxyl group and emission of 1 H from isobutene have been recorded under photolysis of air-saturated pivalate solutions. The CIDNP of butane protons stays as a multiplet. Such changes in the presence of air/oxygen have arisen apparently because of the formation of tert-butylperoxyl free radical and its reaction with tert-butyl radical products, i.e. hydroperoxide (peroxide) and isobutene. Isobutene probably forms a complex with molecular oxygen which has a very short proton relaxation time. During the photolysis of uranyl pivalate in the presence of p-benzoquinone (5 x 10 -2 -0.1 mol dm -3 ) we have not observed any CIDNP, whereas under p-benzoquinone concentrations of 10 -3 -10 -2 mol dm -3 the CIDNP from both hydroquinone and p-benzoquinone has been followed. Photolysis of uranyl propionate has led to CIDNP from butane protons. An emission from methyl group protons of a compound with an ethylperoxyl fragment in the presence of air/oxygen has been observed. The same polarization picture has arisen under interaction of photoexcited uranyl with propionic acid. During the photolysis of uranyl acetate at relatively low concentrations (10 -2 mol dm -3 ) a CIDNP very similar to that registered for uranyl propionate was recorded. The ethyl fragment is probably obtained in reactions for two methyl radicals formed from acetate with the parent uranyl acetate, namely hydrogen-atom abstraction and addition reactions. (author)

  17. Two-dimensional molybdenum disulphide nanoflakes synthesized by liquid-solid phase reaction method: regenerative photocatalytic performance under UV-visible light irradiation by advance oxidation process

    Science.gov (United States)

    Afsar, M. F.; Rafiq, M. A.; Siddique, Fizza; Saira, F.; Chaudhary, M. M.; Hasan, M. M.; Tok, A. I. Y.

    2018-05-01

    Molybdenum disulphide (MoS2) nanoflakes were prepared through liquid-solid phase reaction technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) analysis revealed the formation of pure, polycrystalline, hexagonal phase of MoS2 nanoflakes. The texture coefficient (T{c}hkl) analysis showed that (100) plane was preferentially oriented. The specific surface area of the nanoflakes was 21 m2 g‑1 as determined using Brunaure-Emmett-Teller (BET) technique. A band gap of ∼2.05 eV for MoS2 nanoflakes was estimated from UV-visible spectrum. Regenerative photocatalytic activity of MoS2 nanoflakes was assessed by degrading methylene blue (MB) and safranin-o (SO) dyes under UV-visible light irradiation. Under light irradiation, degradation efficiency for MB was ∼99.58% in 100 min while for SO it was ∼99.89% in 70 min. The MoS2 nanoflakes exhibited excellent photocatalytic performance and good stability in a wide pH range (3–11). MoS2 nanoflakes showed a high reaction rate constant (k app ) for SO ∼ 0.104 49 min‑1 and MB ∼ 0.092 18 min‑1 as compared to other MoS2 nanostructures. The obtained exceptional photocatalytic performance of MoS2 nanoflakes offers potential applications for the treatment of polluted water as well as in other correlated fields.

  18. Crystal structure of the uranyl-oxide mineral rameauite

    Energy Technology Data Exchange (ETDEWEB)

    Plasil, Jakub [ASCR, Prague (Czech Republic). Inst. of Physics; Skoda, Radek [Masaryk Univ., Brno (Czech Republic). Dept. of Geological Sciences; Cejka, Jiri [National Museum, Prague (Czech Republic). Dept. of Mineralogy and Petrology; Bourgoin, Vincent; Boulliard, Jean-Claude [Pierre et Marie Curie Univ., Paris (France). Association Jean Wyart, Collection des Mineraux de Jussieu

    2016-12-15

    Rameauite is a rare supergene uranyl-oxide hydroxy-hydrate mineral that forms during hydration-oxidation weathering of uraninite. On the basis of single-crystal X-ray diffraction data collected on a microfocus source, rameauite is monoclinic, space group Cc, with a = 13.9458(19), b = 14.3105(19), c = 13.8959(18) Aa, β = 118.477(14) , V = 2437.7(6) Aa{sup 3} and Z = 4, with D{sub calc} = 5.467 g cm{sup -3}. The structure of rameauite (R = 0.060 for 1698 unique observed reflections) contains sheets of the β-U{sub 3}O{sub 8} topology, with both UO{sub 6} and UO{sub 7} bipyramids, which is similar to the sheets found in spriggite, ianthinite and wyartite. The sheets alternate with the interlayer, which contains K{sup +}, Ca{sup 2+} and H{sub 2}O molecules. Interstitial cations are linked into infinite chains that extend along [10-1]. Adjacent sheets are linked through K-O, Ca-O and H-bonds. The structural formula of rameauite is K{sub 2} Ca(H{sub 2}{sup [3]}O){sub 1}(H{sub 2}{sup [5]}O){sub 4}[(UO{sub 2}) {sub 6}O{sub 6}(OH){sub 4}](H{sub 2}{sup [4]}O){sub 1}. The empirical formula obtained from the average of eight electron-microprobe analyses is (on the basi s of 6 U p.f.u.) K{sub 1.87}(Ca{sub 1.10}Sr{sub 0.04}){sub Σ1.14}[(UO 2){sub 6}O{sub 6}(OH){sub 4.15}].6H{sub 2}O. The Raman spectrum is dominate d by U.O and O.H vibrations. A discussion of related uranyl-oxide minerals is given.

  19. Growth of uranyl hydroxide nanowires and nanotubes by the electrodeposition method and their transformation to one-dimensional U{sub 3}O{sub 8} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin; Zhao, Ran; Gu, Zhan-jun; Zhao, Yu-liang; Shi, Wei-qun [Key Laboratory of Nuclear Radiation and Nuclear Energy Technology and Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing (China); Chai, Zhi-fang [School of Radiological and Interdisciplinary Sciences, Soochow University, Suzhou (China)

    2014-03-15

    Actinide nanomaterials have great potential for application in the fabrication of nuclear fuels and spent fuel reprocessing in advanced nuclear energy systems. In this work, we used track-etched nanoporous membranes as hard templates to synthesize uranium-based nanomaterials with new structures by electrodeposition. Through electrochemical behavior investigations and subsequent product characterization, the chemical compositions of the deposition product has been confirmed to be uranyl hydroxide. More importantly, accurate control of the morphologies of the deposition product (i.e., nanowires and nanotubes) could be achieved by carefully adjusting the growth parameters such as deposition time and current density. The preferred morphology of the electrodeposition product was nanowires when a low current density was applied, whereas nanotubes could be formed only when a high current density and a short deposition time were both applied. The formation of nanotubes is attributed to the hydrogen bubbles generated by water electrolysis under the overpotential electroreduction conditions. Additionally, we transformed the main chemical composition of the deposition products from uranyl hydroxide to triuranium octoxide by calcination, and SEM results showed that the morphologies of the nanowires and nanotubes were very well maintained after the calcination. Our work provides a useful protocol for the synthesis of one-dimensional uranium-based nanomaterials. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Growth of uranyl hydroxide nanowires and nanotubes by the electrodeposition method and their transformation to one-dimensional U3O8 nanostructures

    International Nuclear Information System (INIS)

    Wang, Lin; Zhao, Ran; Gu, Zhan-jun; Zhao, Yu-liang; Shi, Wei-qun; Chai, Zhi-fang

    2014-01-01

    Actinide nanomaterials have great potential for application in the fabrication of nuclear fuels and spent fuel reprocessing in advanced nuclear energy systems. In this work, we used track-etched nanoporous membranes as hard templates to synthesize uranium-based nanomaterials with new structures by electrodeposition. Through electrochemical behavior investigations and subsequent product characterization, the chemical compositions of the deposition product has been confirmed to be uranyl hydroxide. More importantly, accurate control of the morphologies of the deposition product (i.e., nanowires and nanotubes) could be achieved by carefully adjusting the growth parameters such as deposition time and current density. The preferred morphology of the electrodeposition product was nanowires when a low current density was applied, whereas nanotubes could be formed only when a high current density and a short deposition time were both applied. The formation of nanotubes is attributed to the hydrogen bubbles generated by water electrolysis under the overpotential electroreduction conditions. Additionally, we transformed the main chemical composition of the deposition products from uranyl hydroxide to triuranium octoxide by calcination, and SEM results showed that the morphologies of the nanowires and nanotubes were very well maintained after the calcination. Our work provides a useful protocol for the synthesis of one-dimensional uranium-based nanomaterials. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Microemulsion and Sol-Gel Synthesized ZrO2-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural

    Directory of Open Access Journals (Sweden)

    Almudena Parejas

    2017-12-01

    Full Text Available Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively. Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO2 (especially Zr-SG are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps.

  2. Microemulsion and Sol-Gel Synthesized ZrO₂-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural.

    Science.gov (United States)

    Parejas, Almudena; Montes, Vicente; Hidalgo-Carrillo, Jesús; Sánchez-López, Elena; Marinas, Alberto; Urbano, Francisco J

    2017-12-18

    Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively). Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water) reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO₂ (especially Zr-SG) are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps.

  3. A detailed study of Au-Ni bimetal synthesized by the phase separation mechanism for the cathode of low-temperature solid oxide fuel cells

    Science.gov (United States)

    Yang, Tao; Rodrigues de Almeida, Carlos Manuel; Ramasamy, Devaraj; Almeida Loureiro, Francisco José

    2014-12-01

    A facile co-reduction and annealing synthesis route of nanospheric particles of Au-Ni bimetal with adjustable composition was developed. In a typical synthesis, a direct co-reduction of HAuCl4.4H2O and NiCl2 in aqueous solution was performed with the assistance of reductive NaBH4 and an anionic surfactant sodium dodecyl sulfate (SDS) functioned as the structure-directing agent. Ultrasonic mixing was used at the same time to control the size of the particles. The morphology, microstructure and the state of the surface atoms were analyzed in detail. These nanospheres showed enhanced electrocatalytic activity towards oxygen reduction reaction than that of pure Au nanoparticles, demonstrated in the low temperature SOFC as cathode. The maximum power density generated is 810 mW cm-2 at 550 °C. This is a promising route of taking advantages the Phase Separation Mechanism to greatly reduce the use of noble metals in the ORR field without sacrificing the electrocatalytic activity.

  4. Ultrastructural and metabolic changes in osteoblasts exposed to uranyl nitrate

    International Nuclear Information System (INIS)

    Tasat, D.R.; Orona, N.S.; Mandalunis, P.M.; Cabrini, R.L.; Ubios, A.M.

    2007-01-01

    Exposure to uranium is an occupational hazard to workers who continually handle uranium and an environmental risk to the population at large. Since the cellular and molecular pathways of uranium toxicity in osteoblast cells are still unknown, the aim of the present work was to evaluate the adverse effects of uranyl nitrate (UN) on osteoblasts both in vivo and in vitro. Herein we studied the osteoblastic ultrastructural changes induced by UN in vivo and analyzed cell proliferation, generation of reactive oxygen species (ROS), apoptosis, and alkaline phosphatase (APh) activity in osteoblasts exposed to various UN concentrations (0.1, 1, 10, and 100 μM) in vitro. Cell proliferation was quantified by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, ROS was determined using the nitro blue tetrazolium test, apoptosis was morphologically determined using Hoechst 3332 and APh activity was assayed spectrophotometrically. Electron microscopy revealed that the ultrastructure of active and inactive osteoblasts exposed to uranium presented cytoplasmic and nuclear alterations. In vitro, 1-100 μM UN failed to modify cell proliferation ratio and to induce apoptosis. ROS generation increased in a dose-dependent manner in all tested doses. APh activity was found to decrease in 1-100 μM UN-treated cells vs. controls. Our results show that UN modifies osteoblast cell metabolism by increasing ROS generation and reducing APh activity, suggesting that ROS may play a more complex role in cell physiology than simply causing oxidative damage. (orig.)

  5. Reversible uranyl fluoride nephrotoxicity in the Long Evans rat

    International Nuclear Information System (INIS)

    Diamond, G.L.; Morrow, P.E.; Panner, B.J.; Gelein, R.M.; Baggs, R.B.

    1989-01-01

    Severity and duration of renal injury produced by low levels of uranyl fluoride (UO2F2) were examined in the rat. Rats received multiple ip injections of UO2F2 (cumulative dose: 0.66 or 1.32 mg U/kg body wt). Renal injury was characterized histologically by cellular and tubular necrosis of pars recta of proximal tubule (S2 and S3), with less severe cellular injury to thick ascending limb of loop of Henle and collecting tubule. Injury was evident when renal uranium levels were between 0.7 and 1.4 micrograms U/g wet kidney and was most severe when renal uranium burden was between 3.4 and 5.6 micrograms U/g. Repair of injury was rapid, with complete restoration within 35 days after exposure. Associated with injury were abnormalities in renal function, including impaired tubular reabsorption, proteinuria, and enzymuria, which appeared temporally related, to variable degrees, to progression of renal injury. Thus, reversible renal injury occurs in the rat at levels of uranium in kidney below the present Nuclear Regulatory Commission standard of 3 micrograms U/g kidney for renal injury in humans

  6. Tritium gettering from air with hydrogen uranyl phosphate

    International Nuclear Information System (INIS)

    Souers, P.C.; Uribe, F.S.; Stevens, C.G.; Tsugawa, T.T.

    1985-08-01

    The managers of all tritium facilities now worry about their emissions into the atmosphere. The only method for cleaning tritium out of air is to catalyze the formation of tritiated water which is adsorbed, along with the overwhelming bulk of naturally occurring water vapor, on a zeolite molecular sieve. This method generally costs several million dollars for a small system, because of the necessary steel ducting, compressors and holding tanks. We have long had the dream of finding another getter that might be cheaper to use and would, hopefully, not make tritiated water (HTO). In a previous paper, we discovered that hydrogen uranyl phosphate (HUP, with the formula HUO 2 PO 4 x 4H 2 O) getters 1 ppM of tritium gas out of moist air. This makes HUP the first known ''direct'' tritium getter to work in air. However, the tritium enters a hydroxyl network within the HUP, so that it is effectively still in ''water'' form within the HUP. Worse yet, we found up to 10% tritiated water formed during the previous gettering experiments. HUP is unusual in possessing the exceptionally low vapor pressure of 0.6 torr water vapor at 298 0 K. This allows HUP to be used in fairly dry environments. 14 refs., 3 figs., 2 tabs

  7. Ultrasonic assisted dispersive solid-phase microextraction of Eriochrome Cyanine R from water sample on ultrasonically synthesized lead (II) dioxide nanoparticles loaded on activated carbon: Experimental design methodology.

    Science.gov (United States)

    Bahrani, Sonia; Ghaedi, Mehrorang; Mansoorkhani, Mohammad Javad Khoshnood; Asfaram, Arash; Bazrafshan, Ali Akbar; Purkait, Mihir Kumar

    2017-01-01

    The present research focus on designing an appropriate dispersive solid-phase microextraction (UA-DSPME) for preconcentration and determination of Eriochrome Cyanine R (ECR) in aqueous solutions with aid of sonication using lead (II) dioxide nanoparticles loaded on activated carbon (PbO-NPs-AC). This material was fully identified with XRD and SEM. Influence of pH, amounts of sorbent, type and volume of eluent, and sonication time on response properties were investigated and optimized by central composite design (CCD) combined with surface response methodology using STATISTICA. Among different solvents, dimethyl sulfoxide (DMSO) was selected as an efficient eluent, which its combination by present nanoparticles and application of ultrasound waves led to enhancement in mass transfer. The predicted maximum extraction (100%) under the optimum conditions of the process variables viz. pH 4.5, eluent 200μL, adsorbent dosage 2.5mg and 5min sonication was close to the experimental value (99.50%). at optimum conditions some experimental features like wide 5-2000ngmL -1 ECR, low detection limit (0.43ngmL -1 , S/N=3:1) and good repeatability and reproducibility (relative standard deviation, <5.5%, n=12) indicate versatility in successful applicability of present method for real sample analysis. Investigation of accuracy by spiking known concentration of ECR over 200-600ngmL -1 gave mean recoveries from 94.850% to 101.42% under optimal conditions. The procedure was also applied for the pre-concentration and subsequent determination of ECR in tap and waste waters. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Covalent functionalization of MoS2 nanosheets synthesized by liquid phase exfoliation to construct electrochemical sensors for Cd (II) detection.

    Science.gov (United States)

    Gan, Xiaorong; Zhao, Huimin; Wong, Kwok-Yin; Lei, Dang Yuan; Zhang, Yaobin; Quan, Xie

    2018-05-15

    Surface functionalization is an effective strategy in the precise control of electronic surface states of two-dimensional materials for promoting their applications. In this study, based on the strong coordination interaction between the transition-metal centers and N atoms, the surface functionalization of few-layer MoS 2 nanosheets was successfully prepared by liquid phase exfoliation method in N, N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone, and formamide. The cytotoxicity of surface-functionalized MoS 2 nanosheets was for the first time evaluated by the methylthiazolyldiphenyl-tetrazoliumbromide assays. An electrochemical sensor was constructed based on glass carbon electrode (GCE) modified by MoS 2 nanosheets obtained in DMF, which exhibits relatively higher sensitivity to Cd 2+ detection and lower cytotoxicity against MCF-7 cells. The mechanisms of surface functionalization and selectively detecting Cd 2+ were investigated by density functional theory calculations together with various spectroscopic measurements. It was found that surface-functionalized MoS 2 nanosheets could be generated through Mo-N covalent bonds due to the orbital hybridization between the 5 s orbitals of Mo atoms and the 2p orbitals of N atoms of the solvent molecules. The high selectivity of the sensor is attributed to the coordination reaction between Cd 2+ and O donor atoms of DMF adsorbed on MoS 2 nanosheets. The robust anti-interference is ascribed to the strong binding energy of Cd 2+ and O atoms of DMF. Under the optimum conditions, the electrochemical sensor exhibits highly sensitive and selective assaying of Cd 2+ with a measured detection limit of 0.2 nM and a linear range from 2 nM to 20 μM. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Synthesis of uranyl ion imprinted polymer and its application in analysis

    International Nuclear Information System (INIS)

    Xiao Jingshui; Liu Huijun; Xiao Xilin; Huang Shengli

    2011-01-01

    Uranyl ion imprinted polymer beads were prepared by the copolymerization of styrene monomer and divinyl benzene as crosslinking agent in methanol solution,with the UO 2 2+ -o-dihydroxybenzene-4-vinyl pyridine ternary complex as template, the 2, 2'-azo-bis-isobutyronitrile as initiator and UO 2 2+ as the imprinting ion. The uranyl ions were removed from the polymer beads by treating with 6 mol/L HCl, leaving behind cavities that match uranyl ion in size. The treated polymer beads can preconcentrate uranyl ions from dilute aqueous solutions. The adsorption efficiency can reach 99% or above with good selectivity when pH is in the range of 5-7 and the adsorption time is more than 20 min. The elution rate can reach above 99% under the conditions of concentration of HCl being above 1.0 mol/L, elution time more than 20 min and the elution Janume more than 5 times the Janume of ion imprinted polymer. The uranyl ion imprinted polymer beads have been successfully applied to determine micro-uranium in brine samples. The results are satisfactory compared with NBS method.(authors)

  10. Electron spectra and mechanism of complexing of uranyl nitrate in water-acetone solutions

    International Nuclear Information System (INIS)

    Zazhogin, A.A.; Zazhogin, A.P.; Komyak, A.I.; Serafimovich, A.I.

    2003-01-01

    Based on the analysis of the luminescence and electronic absorption spectra, the processes of complexing in an aqueous solution of UO 2 (NO 3 ) 2 ·6H 2 O with small additions of acetone have been studied. In a pure aqueous solution, uranyl exists as the complex UO 2 ·5H 2 O. It is shown that the addition of acetone to the solution leads to the displacement of some water molecules out of the first coordination sphere of uranyl and the formation of the uranyl nitrate dihydrate complexes UO 2 (NO 3 ) 2 ·2H 2 O. It has been established that the stability of these complexes is determined by the decrease in the water activity and in the degree of hydration of uranyl and nitrate, which is the result of the local increase in the concentration of acetone molecules (due to their hydrophobicity) in the regions of the solution where uranyl and nitrate ions are found. The experimental facts supported the mechanism proposed are presented. (authors)

  11. Time-resolved luminescence studies in hydrogen uranyl phosphate intercalated with amines

    Energy Technology Data Exchange (ETDEWEB)

    Novo, Joao Batista Marques [Departamento de Quimica, Universidade Federal do Parana, CP 19081, 81531-990 Curitiba-PR (Brazil)]. E-mail: jbmnovo@quimica.ufpr.br; Batista, Fabio Roberto [Departamento de Quimica, Universidade Federal do Parana, CP 19081, 81531-990 Curitiba-PR (Brazil); Cunha, Carlos Jorge da [Departamento de Quimica, Universidade Federal do Parana, CP 19081, 81531-990 Curitiba-PR (Brazil); Dias, Lauro Camargo Jr. [Departamento de Quimica, Universidade Federal do Parana, CP 19081, 81531-990 Curitiba-PR (Brazil); Teixeira Pessine, Francisco Benedito [Instituto de Quimica, Universidade Estadual de Campinas, CP 6154, 13084-971 Campinas-SP (Brazil)

    2007-05-15

    Time-resolved luminescence decays of intercalated compounds of hydrogen uranyl phosphate (HUP) with p-toluidinium (HUPPT), benzylaminium (HUPBZ), {alpha}-methylbenzylaminium (HUPMBZ) and hydroxylaminium (HUPHAM) were studied. The prepared compounds belong to the tetragonal P4/ncc space group and showed 00 l reflections shifted to lower angles relative to HUP, indicating that the intercalation increases the c parameter of the unit cell. The luminescence decays of the compounds with 100% of intercalation ratio (HUPHAM and HUPBZ) were analyzed by Global Analysis, assuming Lianos' stretched exponential as the model function, which can be applied to compounds with restricted geometry and mobile donor and quencher molecules. It was remarkable that the luminescence decays showed that the quenching of the emission of the uranyl ions by the intercalated protonated amines is not restricted by low dimensionality of the host uranyl phosphate, and that a diffusion mechanism occurs. Benzylaminium cation efficiently quenches the excited energy of the uranyl ions at close distance, but the long-range and long-lifetime quenching is hindered. A different situation is found in the case of the small hydroxylaminium cation, where the long distance diffusion of the species is fast, playing an important role in the quenching of the excited uranyl ions at longer times.

  12. Time-resolved luminescence studies in hydrogen uranyl phosphate intercalated with amines

    International Nuclear Information System (INIS)

    Novo, Joao Batista Marques; Batista, Fabio Roberto; Cunha, Carlos Jorge da; Dias, Lauro Camargo Jr.; Teixeira Pessine, Francisco Benedito

    2007-01-01

    Time-resolved luminescence decays of intercalated compounds of hydrogen uranyl phosphate (HUP) with p-toluidinium (HUPPT), benzylaminium (HUPBZ), α-methylbenzylaminium (HUPMBZ) and hydroxylaminium (HUPHAM) were studied. The prepared compounds belong to the tetragonal P4/ncc space group and showed 00 l reflections shifted to lower angles relative to HUP, indicating that the intercalation increases the c parameter of the unit cell. The luminescence decays of the compounds with 100% of intercalation ratio (HUPHAM and HUPBZ) were analyzed by Global Analysis, assuming Lianos' stretched exponential as the model function, which can be applied to compounds with restricted geometry and mobile donor and quencher molecules. It was remarkable that the luminescence decays showed that the quenching of the emission of the uranyl ions by the intercalated protonated amines is not restricted by low dimensionality of the host uranyl phosphate, and that a diffusion mechanism occurs. Benzylaminium cation efficiently quenches the excited energy of the uranyl ions at close distance, but the long-range and long-lifetime quenching is hindered. A different situation is found in the case of the small hydroxylaminium cation, where the long distance diffusion of the species is fast, playing an important role in the quenching of the excited uranyl ions at longer times

  13. Kinetic studies of uranyl ion adsorption on acrylonitrile (AN) / polyethylene glycol (PEG) interpenetrating networks (IPN)

    International Nuclear Information System (INIS)

    Aycik, G.A.; Gurellier, R.

    2004-01-01

    The kinetics of the adsorption of uranyl ions on amidoximated acrylonitrile (AN)/ polyethylene glycol (PEG) interpenetrating network (IPNs) from aqueous solutions was studied as a function of time and temperature. Adsorption analyses were performed for definite uranyl ion concentrations of 1x10 -2 M and at four different temperatures as 290K, 298K, 308K and 318K. Adsorption time was increased from zero to 48 hours. Adsorption capacities of uranyl ions by PEG/AN IPNS were determined by gamma spectrometer. The results indicate that adsorption capacity increases linearly with increasing temperature. The max adsorption capacity was found as 602 mgu/g IPN at 308K. Adsorption rate was evaluated from the curve plotted of adsorption capacity versus time, for each temperature. Rate constants for uranyl ions adsorption on amidoximated ipns were calculated for 290K, 298K, 308K and 318K at the solution concentration of 1x10 -2 M . The results showed that as the temperature increases the rate constant increases exponentially too. The mean activation energy of uranyl ions adsorption was found as 34.6 kJ/mole by using arrhenius equation. (author)

  14. Quenching of excited uranyl ion during its photochemical reduction with triphenyl-phosphine : Part IV - effect of heterocyclic molecules

    International Nuclear Information System (INIS)

    Sidhu, M.S.; Bhatia, P.V.K.

    1994-01-01

    The presence of heterocyclic compounds triggers off a competition between photophysical and photochemical annihilation of excited uranyl ion during its photochemical reduction with triphenylphosphine. This competition is used to measure Stern-Volmer constant using UV visible spectrophotometer for quenching the uranyl ion luminescence with a number of heterocyclic molecules viz., pyridine, thiophene bipyridyl, tetrahydrofuran and piperidine. (author). 7 refs., 2 figs., 1 tab

  15. Aqueous uranyl complexes. 3. Potentiometric measurements of the hydrolysis of uranyl(VI) ion at 25 degrees C

    International Nuclear Information System (INIS)

    Palmer, D.A.; Nguyen-Trung, C.

    1995-01-01

    Potentiometric titrations of uranyl(VI) solutions were conducted using a standard glass/calomel electrode combination over the pH range 3 to 12 at 0.1 mol-kg -1 ionic strength with tetramethylammonium trifluoromethanesulfonate as the supporting electrolyte. The electrodes were calibrated directly on the hydrogen ion concentration scale during the initial stage of each titration. The species, UO 2 2+ , (UO 2 ) 2 (OH) 2 2+ , (UO 2 ) 3 (OH) 5 + , (UO 2 ) 3 (OH) 7 - , (UO 2 ) 3 (OH) 8 2- , and (UO 2 ) 3 (OH) 10 4- identified in an earlier Raman study were compatible with the analysis of the titration data. Based on this analysis and application of the extended Debye-Hueckel treatment, the polynuclear species indicated above were assigned overall formation constants at 25 degrees C and at infinite dilution of -5.51±0.04, -15.3±0.1, -27.77±0.09, -37.65±0.14, and -62.4±0.3, respectively. The results are discussed in reference to hydrolysis quotients reported in the literature for the first three species. Formation quotients for the last two species have not been reported previously

  16. Synthesis and crystal structure analysis of uranyl triple acetates

    Energy Technology Data Exchange (ETDEWEB)

    Klepov, Vladislav V., E-mail: vladislavklepov@gmail.com [Institute for Energy and Climate Research (IEK-6), Forschungszentrum Jülich GmbH, 52428 Jülich (Germany); Department of Chemistry, Samara National Research University, 443086 Samara (Russian Federation); Serezhkina, Larisa B.; Serezhkin, Victor N. [Department of Chemistry, Samara National Research University, 443086 Samara (Russian Federation); Alekseev, Evgeny V., E-mail: e.alekseev@fz-juelich.de [Institute for Energy and Climate Research (IEK-6), Forschungszentrum Jülich GmbH, 52428 Jülich (Germany); Institut für Kristallographie, RWTH Aachen University, 52066 Aachen (Germany)

    2016-12-15

    Single crystals of triple acetates NaR[UO{sub 2}(CH{sub 3}COO){sub 3}]{sub 3}·6H{sub 2}O (R=Mg, Co, Ni, Zn), well-known for their use as reagents for sodium determination, were grown from aqueous solutions and their structural and spectroscopic properties were studied. Crystal structures of the mentioned phases are based upon (Na[UO{sub 2}(CH{sub 3}COO){sub 3}]{sub 3}){sup 2–} clusters and [R(H{sub 2}O){sub 6}]{sup 2+} aqua-complexes. The cooling of a single crystal of NaMg[UO{sub 2}(CH{sub 3}COO){sub 3}]{sub 3}·6H{sub 2}O from 300 to 100 K leads to a phase transition from trigonal to monoclinic crystal system. Intermolecular interactions between the structural units and their mutual packing were studied and compared from the point of view of the stereoatomic model of crystal structures based on Voronoi-Dirichlet tessellation. Using this method we compared the crystal structures of the triple acetates with Na[UO{sub 2}(CH{sub 3}COO){sub 3}] and [R(H{sub 2}O){sub 6}][UO{sub 2}(CH{sub 3}COO){sub 3}]{sub 2} and proposed reasons of triple acetates stability. Infrared and Raman spectra were collected and their bands were assigned. - Graphical abstract: Single crystals of uranium based triple acetates, analytical reagents for sodium determination, were synthesized and structurally, spectroscopically and topologically characterized. The structures were compared with the structures of compounds from preceding families [M(H{sub 2}O){sub 6})][UO{sub 2}(CH{sub 3}COO){sub 3}]{sub 2} (M = Mg, Co, Ni, Zn) and Na[UO{sub 2}(CH{sub 3}COO){sub 3}]. Analysis was performed with the method of molecular Voronoi-Dirichlet polyhedra to reveal a large contribution of the hydrogen bonds into intermolecular interactions which can be a reason of low solubility of studied complexes.

  17. Decomposition of uranyl peroxo-carbonato complex ion in the presence of metal oxides in carbonate media

    International Nuclear Information System (INIS)

    Dong-Yong Chung; Min-Sung Park; Keun-Young Lee; Eil-Hee Lee; Kwang-Wook Kim; Jei-Kwon Moon

    2015-01-01

    Uranium oxide was dissolved in the form of the uranyl peroxo-carbonato complex ion, UO 2 (O 2 )(CO 3 ) 2 4- in carbonate solutions with hydrogen peroxide. When UO 2 (O 2 )(CO 3 ) 2 4- ions lose their peroxide component, they become a stable species of uranyl tricarbonato complex ion, UO 2 (O 2 )(CO 3 ) 2 4- . The uranyl peroxo-carbonato complex self-decomposed more rapidly into the uranyl tricarbonato complex ion in the presence of a metal oxide in the carbonate solution. In this study, decomposition of the uranyl peroxo-carbonato complex in a carbonate solution was investigated in the presence of several metal oxides using absorption spectroscopy. (author)

  18. Time-resolved luminescence spectroscopy of trace uranyl in wet sand

    International Nuclear Information System (INIS)

    Freed, D.

    1993-01-01

    The objective of the project was to develop a technique to observe and characterize the behaviour of uranium in unsaturated groundwater flow systems, particularly with regard to unstable ''fingered'' flow, which could drastically reduce time of travel. The actual experimental work described was a study of the feasibility of detecting uranyl at the parts-per-billion level in aqueous solution by means of its luminescence spectrum. A high-power UV laser was used to excite aqueous uranyl in a wet sand mixture; the characteristic green phosphorescence emitted in the decay transition was detected by a photomultiplier tube; and the amplified signal was sent to an oscilloscope in communication with Macintosh data acquisition software. At the time of the conference, a more sophisticated sample configuration for imaging the flow of uranyl was already under development. 5 refs., 3 figs

  19. Time-resolved luminescence spectroscopy of trace uranyl in wet sand

    Energy Technology Data Exchange (ETDEWEB)

    Freed, D [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1994-12-31

    The objective of the project was to develop a technique to observe and characterize the behaviour of uranium in unsaturated groundwater flow systems, particularly with regard to unstable ``fingered`` flow, which could drastically reduce time of travel. The actual experimental work described was a study of the feasibility of detecting uranyl at the parts-per-billion level in aqueous solution by means of its luminescence spectrum. A high-power UV laser was used to excite aqueous uranyl in a wet sand mixture; the characteristic green phosphorescence emitted in the decay transition was detected by a photomultiplier tube; and the amplified signal was sent to an oscilloscope in communication with Macintosh data acquisition software. At the time of the conference, a more sophisticated sample configuration for imaging the flow of uranyl was already under development. 5 refs., 3 figs.

  20. Contribution to the study of uranyl salts in butyl phosphate solutions

    International Nuclear Information System (INIS)

    Coulon, A.

    1965-06-01

    A spectroscopic study in the normal infrared region and involving the following associations: tri-alkyl phosphates (tri-butyl, tri-ethyl, tri-methyl), uranyl salts (nitrate, chloride, acetate) has confirmed the existence of an interaction between the phosphoryl group and the uranium atom, as shown by a movement of absorption band for the valency P = 0 from ∼ 1270 cm -1 to ∼ 1180 cm -1 . A study of the preparation, analysis and spectroscopy of the solids obtained by the precipitation of uranyl salts by acid butyl phosphates has been carried out. By infrared spectrophotometry it has been shown that the tri-butyl and di-butyl phosphates are associated in non-polar diluents even before the uranium is introduced. The extraction of uranyl salts from acid aqueous solutions by a diluted mixture of tri-butyl and di-butyl phosphates proceeds by different mechanisms according to the nature of the ion (nitrate or chloride). (author) [fr

  1. Uranyl adsorption kinetics within silica gel: dependence on flow velocity and concentration

    Science.gov (United States)

    Dodd, Brandon M.; Tepper, Gary

    2017-09-01

    Trace quantities of a uranyl dissolved in water were measured using a simple optical method. A dilute solution of uranium nitrate dissolved in water was forced through nanoporous silica gel at fixed and controlled water flow rates. The uranyl ions deposited and accumulated within the silica gel and the uranyl fluorescence within the silica gel was monitored as a function of time using a light emitting diode as the excitation source and a photomultiplier tube detector. It was shown that the response time of the fluorescence output signal at a particular volumetric flow rate or average liquid velocity through the silica gel can be used to quantify the concentration of uranium in water. The response time as a function of concentration decreased with increasing flow velocity.

  2. Engineering of specific uranyl-coordination sites in the calcium-binding motif of Calmodulin

    International Nuclear Information System (INIS)

    Beccia, M.; Pardoux, R.; Sauge-Merle, S.; Bremond, N.; Lemaire, D.; Berthomieu, C.; Delangle, P.; Guilbaud, P.

    2014-01-01

    Complete text of publication follows: Characterization of heavy metals interactions with proteins is fundamental for understanding the molecular factors and mechanisms governing ions toxicity and speciation in cells. This line of research will also help in developing new molecules able to selectively and efficiently bind toxic metal ions, which could find application for bio-detection or bioremediation purposes. We have used the regulatory calcium-binding protein Calmodulin (CaM) from A. thaliana as a structural model and, starting from it, we have designed various mutants by site-directed mutagenesis. We have analysed thermodynamics of uranyl ion binding to both sites I and II of CaM N-terminal domain and we have identified structural factors governing this interaction. Selectivity for uranyl ion has been tested by studying reactions of the investigated peptides with Ca 2+ , in the same conditions used for UO 2 2+ . Spectro-fluorimetric titrations and FTIR analysis have shown that the affinity for uranyl increases by phosphorylation of a threonine in site I, especially approaching the physiological pH, where the phospho-threonine side chain is deprotonated. Based on structural models obtained by Molecular Dynamics, we tested the effect of a two residues deletion on site I properties. We obtained an almost two orders of magnitude increase in affinity for uranyl, with a sub-nanomolar dissociation constant for the uranyl complex with the non phosphorylated peptide, and an improved uranyl/calcium selectivity. Allosteric effects depending on Ca 2+ and UO 2 2+ binding have been investigated by comparing thermodynamic parameters obtained for mutants having both sites I and II able to chelate metal ions with those of mutants consisting of just one active site

  3. Structural characterization of Mg{sub 3}MnH{sub {approx}}{sub 6}--a new high-pressure phase synthesized in a multi-anvil cell at 6 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Blomqvist, Helen; Roennebro, Ewa; Kyoi, Daisuke; Sakai, Tetsuo; Noreus, Dag

    2003-08-25

    With modern X-ray diffraction refinement methods it was shown to be possible to identify a new Mg{sub 3}MnH{sub {approx}}{sub 6} phase from a minute sample volume in spite of poor crystallinity and coexisting impurity phases. The new hydride was synthesized at 6 GPa in a high-pressure multi-anvil cell at 873 K. A monoclinic unit cell was found with a=8.827(2), b=4.657(2), c=4.676(2) A and {beta}=105.74(2) deg., space group P2{sub 1}/m (no. 11), Z=2, V=184.99 A{sup 3}. Manganese is surrounded by a distorted cube of magnesium with average Mn-Mg distances of 2.78(2) A. The cubes share edges in the b and c directions of the unit cell but are separated by a distance of {approx}3.6 A along a, forming a layered structure. The hydrogen positions were not possible to determine, as only a small sample amount could be prepared. If the metal atom structure of the title compound is compared to the already known Mg{sub 3}MnH{sub 7} it can be concluded that Mg{sub 3}MnH{sub {approx}}{sub 6} also consists of manganese hydrido complexes counterbalanced by magnesium ions, but with a different alignment of the magnesium cubes.

  4. Crystal field influence on vibration spectra: anhydrous uranyl chloride and dihydroxodiuranyl chloride tetrahydrate

    International Nuclear Information System (INIS)

    Perrin, Andre; Caillet, Paul

    1976-01-01

    Vibrational spectra of anhydrous uranyl chloride UO 2 Cl 2 and so called basic uranyl chloride: dihydroxodiuranyl chloride tetrahydrate /UO 2 (OH) 2 UO 2 /Cl 2 (H 2 O) 4 are reported. Factor group method analysis leads for the first time to complete and comprehensive interpretation of their spectra. Two extreme examples of crystal field influence on vibrational spectra are pointed out: for UO 2 Cl 2 , one is unable to explain spectra without taking into account all the elements of primitive crystalline cell, whilst for dihydroxodiuranyl dichloride tetrahydrate the crystal packing has very little effect on vibrational spectra [fr

  5. The treatment of uranyl nitrate from the AMOR process for VKTA Rossendorf

    International Nuclear Information System (INIS)

    Boessert, W.; Krempl, R.; Miller, J.W.

    2003-01-01

    The blending of uranyl nitrate solutions at VKTA and its subsequent treatment at BNFL-Sellafield is a significant step towards the safe and effective treatment of these enriched uranyl nitrate solutions. Overall the integration of the expertise of the international company BNFL/Westinghouse will lead to the achievement of a successful solution. This success has involved the integration of the project management and operational facilities of BNFL Sellafield with the local planning, design and manufacture capacities of Westinghouse Reaktor GmbH. (orig.)

  6. Controlled deprotection and reorganization of uranyl oxo groups in a binuclear macrocyclic environment

    International Nuclear Information System (INIS)

    Jones, Guy M.; Arnold, Polly L.; Love, Jason B.

    2012-01-01

    Switching on uranium(V) reactivity: The silylated uranium(V) dioxo complex [(Me_3SiOUO)_2(L)_2] (A) is inert to oxidation, but after two-electron reduction to [(Me_3SiOUO)_2(L)]"2"- (1), it can be desilylated to form [OU(μ-O)_2UO(L)_2]"2"- (2) with reinstated uranyl character. Removal of the silyl group uncovers new redox and oxo rearrangement chemistry for uranium, thus reforming the uranyl motif and involving the U"V"I"/"V couple in dioxygen reduction. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Controlled deprotection and reorganization of uranyl oxo groups in a binuclear macrocyclic environment

    International Nuclear Information System (INIS)

    Jones, Guy M.; Arnold, Polly L.; Love, Jason B.

    2012-01-01

    The silylated uranium(V) dioxo complex [(Me_3SiOUO)_2(L)_2] is inert to oxidation, but after two-electron reduction to [(Me_3SiOUO)_2(L)]"2"-, it can be desilylated to form [OU(μ-O)_2UO(L)_2]"2"- with reinstated uranyl character. Removal of the silyl group uncovers new redox and oxo rearrangement chemistry for uranium, thus reforming the uranyl motif and involving the U"V"I"/"V couple in dioxygen reduction. [de

  8. Kinetic analysis of laser induced phosphorescence in uranyl phosphate for improved analytical measurements

    International Nuclear Information System (INIS)

    Bushaw, B.A.

    1983-10-01

    Pulsed dye-laser excitation with multichannel scaler photon counting is used to obtain time resolved emission spectra of uranyl ions in aqueous solution. Kinetic analysis of this data corrects for matrix quenching and temperature effects which reduce the quantum yield of the uranyl ion luminescence. The method gives accurate measurements without separative prechemistry or the use of internal standards. Detection limits of one part-per-trillion (pptr) have been demonstrated, and in samples with concentrations greater than 100 pptr, relative standard deviations of less than 3% are achieved routinely

  9. Removal of uranyl ions by p-hexasulfonated calyx[6]arene acid

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, Ioana-Carmen [R and D National Institute for Metals and Radioactive Resources–ICPMRR, B-dul Carol I No.70, Sector 2, Bucharest 020917 (Romania); Petru, Filip [“C.D. Nenitescu” Institute of Organic Chemistry, Splaiul Independentei 202B, Sector 6, Bucharest 71141 (Romania); Humelnicu, Ionel [“Al.I. Cuza” University of Iasi, The Faculty of Chemistry, Bd. Carol-I No. 11, Iasi 700506 (Romania); Mateescu, Marina [National R and D Institute for Chemistry and Petrochemistry, Splaiul Independenţei No. 202, Bucharest 060021 (Romania); Militaru, Ecaterina [R and D National Institute for Metals and Radioactive Resources–ICPMRR, B-dul Carol I No.70, Sector 2, Bucharest 020917 (Romania); Humelnicu, Doina, E-mail: doinah@uaic.ro [“Al.I. Cuza” University of Iasi, The Faculty of Chemistry, Bd. Carol-I No. 11, Iasi 700506 (Romania)

    2014-10-15

    Radioactive pollution is a significant threat for the people’s health. Therefore highly effective radioactive decontamination methods are required. Ion exchange, biotechnologies and phytoremediation in constructed wetlands have been used as radioactive decontamination technologies for uranium contaminated soil and water remediation. Recently, beside those classical methods the calix[n]arenic derivatives’ utilization as radioactive decontaminators has jogged attention. The present work aims to present the preliminary research results of uranyl ion sorption studies on the p-hexasulfonated calyx[6]arenic acid. The effect of temperature, contact time, sorbent amount and uranyl concentration variation on sorption efficiency was investigated. Isotherm models revealed that the sorption process fit better Langmuir isotherm.

  10. Investigation of regularities of uranyl salts complexing with neutral bases in nonaqueous media

    International Nuclear Information System (INIS)

    Kobets, L.V.; Buchikhin, E.P.

    1986-01-01

    Anhydrous uranyl chloride complexing with neutral oxygen-containing organic bases (sulfoxides, organic phosphates, phosphinates, phosphinoxides, N-oxides) in the acetone medium depending on the donor capacity of neutral molecules is discussed. The constants of 1:1 complexes dissociation are shown to detect no correlation with the donor capacity of neutral bases. At the same time stability constants of complexes increase as the donor capacity of ligands grows. But the dependence is of a complex character and is determined by the nature of neutral molecules. Estimation of uranyl chloride and 0-donor contributions into the values of stability constants and complex formation heats is given

  11. Ultrastructure changes produced by the action of uranyl acetate on the human erythrocyte in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Wyatt, J H

    1975-06-01

    Human erythrocytes exposed in vitro to low concentrations of uranyl ions are immediately changed in shape to stomatocytes. Electron microscope examination demonstrates that cellular damage is confined to the plasma membrane. Endocytosis of the cell membrane produces groups of inside out membrane-lined vesicles within the cell; lipid from the membrane enters the cell, giving rise to intracellular myelin figures, and breaks are seen in the cell membrane. It is proposed that the lipid fraction of the cell membrane is the primary target for damage by uranyl ions.

  12. Determination of uranium in uranyl nitrate solutions of nuclear grade quality - Gravimetric method

    International Nuclear Information System (INIS)

    1990-01-01

    This international Standard specifies a precise and accurate gravimetric method for determining the uranium content in uranyl nitrate product solutions of nuclear grade quality at concentrations above 100 g/l of uranium. Non-volatile impurities influence the accuracy of the method. Uranyl nitrate is converted into uranium octoxide (U 3 O 8 ) by ignition in air to constant mass at 900 deg. C ± 10 deg. C. Calculation of the uranium content in the sample using a gravimetric conversion factor which depends on the isotopic composition of the uranium. The isotopic composition is determined by mass spectrometry

  13. First start-up of nuclear criticality safety experiment facility for uranyl nitrate solution

    International Nuclear Information System (INIS)

    Zhu Qingfu; Shi Yongqian; Shen Leisheng; Hu Dingsheng; Zhao Shouzhi; He Tao; Sun Zheng; Lin Shenghuo; Yao Shigui

    2005-01-01

    The uranyl nitrate solution experiment facility for the research on nuclear criticality safety is described. The nuclear fuel loading steps in the first start-up for water-reflected core are presented. During the experiments, the critical volume of uranyl nitrate solution was determined as 20479.62 mL with count rate inverse extrapolation method, reactivity interpolation method, and steady power method. By calculation, critical mass of 235 U was derived as 1579.184 g from experimental data. The worth of control rods was also calibrated in the first start-up of the facility. (authors)

  14. Interaction of aluminium(3) with uranyl ions in the course of joint hydrolysis

    International Nuclear Information System (INIS)

    Yusov, A.B.; Budantseva, N.A.; Fedoseev, A.M.; Astafurova, L.N.

    2001-01-01

    By means of spectrophotometry, luminescence and IR-spectroscopy one studied interaction of uranyl ions with Al 3+ ions in solutions at pH≥2 and in precipitates at pH≥5. It is shown that within 3-4 pH range the uranyl hydrolyzed forms interact with these of aluminium. Mixed hydroxoaquacomplexes are likely to be formed in solution with U:Al = 1:1 molar ratio. Large-size mixed polymers may be formed with pH increase. Varying of precipitation pH from 5 up to 14 does not minimize the importance of the oligomer mixed compounds for precipitation formation [ru

  15. Ultrastructure changes produced by the action of uranyl acetate on the human erythrocyte in vitro

    International Nuclear Information System (INIS)

    Wyatt, J.H.

    1975-06-01

    Human erythrocytes exposed in vitro to low concentrations of uranyl ions are immediately changed in shape to stomatocytes. Electron microscope examination demonstrates that cellular damage is confined to the plasma membrane. Endocytosis of the cell membrane produces groups of inside out membrane-lined vesicles within the cell; lipid from the membrane enters the cell, giving rise to intracellular myelin figures, and breaks are seen in the cell membrane. It is proposed that the lipid fraction of the cell membrane is the primary target for damage by uranyl ions. (author)

  16. Complete removal of uranyl nitrate from tissue matrix using supercritical fluid extraction

    International Nuclear Information System (INIS)

    Kumar, R.; Sivaraman, N.; Senthil Vadivu, E.; Srinivasan, T.G.; Vasudeva Rao, P.R.

    2003-01-01

    The removal of uranyl nitrate from tissue matrix has been studied with supercritical carbon dioxide modified with methanol alone as well as complexing reagents dissolved in methanol. A systematic study of various complexing agents led to the development of an extraction procedure for the quantitative recovery of uranium from tissue matrix with supercritical carbon dioxide modified with methanol containing small quantities of acetylacetone. The drying time and temperature employed in loading of uranyl nitrate onto tissue paper were found to influence the extraction efficiency significantly

  17. Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with Fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry.

    Science.gov (United States)

    Pasilis, Sofie; Somogyi, Arpád; Herrmann, Kristin; Pemberton, Jeanne E

    2006-02-01

    Electrospray ionization (ESI) of uranyl nitrate solutions generates a wide variety of positively and negatively charged ions, including complex adducts of uranyl ions with methoxy, hydroxy, and nitrate ligands. In the positive ion mode, ions detected by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry are sensitive to instrumental tuning parameters such as quadrupole operating frequency and trapping time. Positive ions correspond to oligomeric uranyl nitrate species that can be characterized as having a general formula of [(UO(2))(n)(A)(m)(CH(3)OH)(s)](+) or [(UO(2))(n)(O)(A)(m)(CH(3)OH)(s)](+) with n = 1-4, m = 1-7, s = 0 or 1, and A = OH, NO(3), CH(3)O or a combination of these, although the formation of NO(3)-containing species is preferred. In the negative ion mode, complexes of the form [(UO(2))(NO(3))(m)](-) (m = 1-3) are detected, although the formation of the oxo-containing ions [(UO(2))(O)(n)(NO(3))(m)](-) (n = 1-2, m = 1-2) and the hydroxy-containing ions [(UO(2))(OH)(n)(NO(3))(m)](-) (n = 1-2, m = 0-1) are also observed. The extent of coordinative unsaturation of both positive and negative ions can be determined by ligand association/exchange and H/D exchange experiments using D(2)O and CD(3)OD as neutral reaction partners in the gas-phase. Positive ions are of varying stability and reactivity and may fragment extensively upon collision with D(2)O, CD(3)OD and N(2) in sustained off-resonance irradiation/collision-induced dissociation (SORI-CID) experiments. Electron-transfer reactions, presumably occurring during electrospray ionization but also in SORI-CID, can result in reduction of U(VI) to U(V) and perhaps even U(IV).

  18. Characterization of osteopontin-uranyl interaction: role of multiple phosphorylations

    International Nuclear Information System (INIS)

    Qi, Lei

    2014-01-01

    While some metals are essential for Life, other ones are only toxicants for living organisms, tolerated below well-definite concentrations. This is the case for uranium, a natural element which has no known biological function. It is a low α emitter and its chemical toxicity rather than its radiological toxicity is a subject of concern. Once in the body, this metal reaches the blood and accumulates in the bones under the action of unknown mechanisms. Uranium mainly exists in form of uranyl ion (UO 2 2+ ) in aqueous media and particularly reacts with carboxylates, phenolates and phosphates of the proteins. Previous studies have highlighted that UO 2 2+ modulates the SPP1 expression, a gene which codes for osteopontin (OPN). This highly phosphorylated glycoprotein plays an important role in bone homeostasis. This role and its biochemical properties led us to hypothesize that OPN might be a potential target of UO 2 2+ and involved in its accumulation in bones. A simple and original purification process was optimized to produce very highly purified OPN starting from human and bovine milk. Various biophysical approaches were set up and confirmed that both bovine and human OPN display very high affinity for UO 2 2+ . Moreover, the formation of stable UO 2 -protein complexes originating from structural changes was evidenced. The major role of phosphorylations, both on the OPN's affinity for UO 2 2+ and the stability of the UO 2 -protein complexes, was confirmed. These results demonstrate that OPN presents all the characteristics to be a major UO 2 2+ binding-protein in vitro, and they open new insights in the understanding of the UO 2 2+ mineralization process mechanisms. (author) [fr

  19. Mechanism of acute renal failure after uranyl nitrate

    International Nuclear Information System (INIS)

    Blantz, R.C.; Konnen, K.

    1975-01-01

    Administration of 25 mg/kg uranyl nitrate (UN) to rats leads to a brief period of polyuria followed by progressive oliguria with death at 5 days. Factors that determine glomerular filtration rate (GFR) were examined in control Munich--Wistar rats (n = 16) and 2 h after either 15 mg/kg (n = 8) or 25 kg/kg (n = 7) of UN (i.v.) utilizing direct measurements of hydrostatic and oncotic pressures and plasma flow. Total kidney GFR was reduced to 47 percent of control in the low dose group and to 21 percent in the high dose group. The simultaneous nephron filtration rate (sngfr) was 28.6 +- 0.8 nl/min/g kidney wt in control, 29.1 +- 1.0 in the low dose group, and 18.1 +- 1.2 (P less than 0.001) in the higher dose group. Nephron plasma flow was equal to control at both doses of UN. Also directly measured hydrostatic pressure gradient across the glomerular capillary was not changed. The effective filtration pressure achieved equilibrium in control animals but became significantly positive at the efferent end of the capillary at both doses of UN and increased. Total glomerular permeability (L/sub p/A) was progressively reduced from control (0.089 +- 0.005 nl/s/g kidney wt/mm Hg) at low dose UN (0.047 +- 0.013) and high dose (0.024 +- 0.003 nl/s/g kidney wt/mm Hg). Therefore UN decreases GFR by two mechanisms: (a) tubular damage leading to back-diffusion of solutes and (b) a primary reduction in sngfr due to reduced L/sub p/A

  20. Standard test method for isotopic analysis of hydrolyzed uranium hexafluoride and uranyl nitrate solutions by thermal ionization mass spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This method applies to the determination of isotopic composition in hydrolyzed nuclear grade uranium hexafluoride. It covers isotopic abundance of 235U between 0.1 and 5.0 % mass fraction, abundance of 234U between 0.0055 and 0.05 % mass fraction, and abundance of 236U between 0.0003 and 0.5 % mass fraction. This test method may be applicable to other isotopic abundance providing that corresponding standards are available. 1.2 This test method can apply to uranyl nitrate solutions. This can be achieved either by transforming the uranyl nitrate solution to a uranyl fluoride solution prior to the deposition on the filaments or directly by depositing the uranyl nitrate solution on the filaments. In the latter case, a calibration with uranyl nitrate standards must be performed. 1.3 This test method can also apply to other nuclear grade matrices (for example, uranium oxides) by providing a chemical transformation to uranyl fluoride or uranyl nitrate solution. 1.4 This standard does not purport to address al...

  1. Precipitation characteristics of uranyl ions at different pHs depending on the presence of carbonate ions and hydrogen peroxide.

    Science.gov (United States)

    Kim, Kwang-Wook; Kim, Yeon-Hwa; Lee, Se-yoon; Lee, Jae-Won; Joe, Kih-Soo; Lee, Eil-Hee; Kim, Jong-Seung; Song, Kyuseok; Song, Kee-Chan

    2009-04-01

    This work studied the dissolution of uranium dioxide and precipitation characteristics of uranyl ions in alkaline and acidic solutions depending on the presence of carbonate ions and H2O2 in the solutions at different pHs controlled by adding HNO3 or NaOH in the solution. The chemical structures of the precipitates generated in different conditions were evaluated and compared by using XRD, SEM, TG-DT, and IR analyses together. The sizes and forms of the precipitates in the solutions were evaluated, as well. The uranyl ions were precipitated in the various forms, depending on the solution pH and the presences of hydrogen peroxide and carbonate ions in the solution. In a 0.5 M Na2CO3 solution with H2O2, where the uranyl ions formed mixed uranyl peroxy-carbonato complexes, the uranyl ions were precipitated as a uranium peroxide of UO4(H20)4 at pH 3-4, and precipitated as a clarkeite of Na2U2Ox(OH)y(H2O)z above pH 13. In the same carbonate solution without H2O2, where the uranyl ions formed uranyl tris-carbonato complex, the uranyl ions were observed to be precipitated as a different form of clarkeite above pH 13. The precipitate of uranyl ions in a nitrate solution without carbonate ions and H2O2 at a high pH were studied together to compare the precipitate forms in the carbonate solutions.

  2. Application of the NICADonnan model for proton, copper and uranyl binding to humic acid

    NARCIS (Netherlands)

    Saito, T.; Nagasaki, S.; Tanaka, S.; Koopal, L.K.

    2004-01-01

    Humic acids are natural organic materials that play an important role in the migration of heavy metal and actinide ions in aquatic and soil systems. In the present study, the binding of protons, copper ions and uranyl ions to the purified Aldrich humic acid (PAHA) is investigated and the results are

  3. Vibrational spectra of monouranates and uranium hydroxides as reaction products of alkali with uranyl nitrate

    International Nuclear Information System (INIS)

    Komyak, A.I.; Umrejko, D.S.; Posledovich, M.R.

    2013-01-01

    Vibrational (IR absorption and Raman scattering) spectra for the reaction products of uranyl nitrate hexahydrate with NaOH and KOH have been studied. As a result of exchange reactions, the uranyl-ion coordinated nitrate groups are completely replaced by hydroxyl ions and various uranium and uranyl oxides or hydrates are formed. An analysis of the vibrations has been performed in terms of the frequencies of a free or coordinated nitrate group; comparison with the vibrations of the well-known uranium oxides and of the uranyl group UO 2 2+ has been carried out. Vibrational spectra of a free nitrate group are characterized by four vibrational frequencies 1050, 724, 850, and 1380 cm -1 , among which the frequencies at 724 and 1380 cm -1 are doubly degenerate and attributed to E’ symmetry of the point group D 3h . When this group is uranium coordinated, its symmetry level is lowered to C 2v , all vibrations of this group being active both in Raman and IR spectra. The doubly degenerate vibrations are exhibited as two bands and a frequency of the out-of-plane vibration is lowered to 815 cm -1 . (authors)

  4. Identification of Uranyl Surface Complexes an Ferrihydrite: Advanced EXAFS Data Analysis and CD-MUSIC Modeling

    NARCIS (Netherlands)

    Rossberg, A.; Ulrich, K.U.; Weiss, S.; Tsushima, S.; Hiemstra, T.; Scheinost, A.C.

    2009-01-01

    Previous spectroscopic research suggested that uranium(VI) adsorption to iron oxides is dominated by ternary uranyl-carbonato surface complexes across an unexpectedly wide pH range. Formation of such complexes would have a significant impact on the sorption behavior and mobility of uranium in

  5. Modeling of critical experiments employing Raschig rings in uranyl nitrate solution

    International Nuclear Information System (INIS)

    Tanner, J.E.

    1989-01-01

    Four critical experiments employing borated glass rings in concentrated uranyl nitrate solution yielded k eff higher by 0. 04 when modeled with a flux-weighted, homogenized cross section set than when modeled with discrete rings. k eff varied by 0.014 for a 10% boron uncertainty and by up to 0.04 for a 10% packing fraction uncertainty

  6. Study of the mechanism and kinetics of the reduction of uranyl ions in phosphoric acid solutions

    International Nuclear Information System (INIS)

    El Kacemi, K.; Tyburce, B.; Belcadi, S.

    1982-01-01

    The electrochemical reduction of uranyl ions in 0.1 to 9 M phosphoric acid has been investigated by polarography, cyclic voltammetry, chronopotentiometry and potentiostatic coulometry. In concentrated phosphoric acid solutions (H 3 PO 4 3 PO 4 concentrations. So, when the concentration of U(VI) increases and/or that of H 3 PO 4 reduces, the system becomes reversible. (author)

  7. Recuperation of uranyl ions from effluents by means of microbiological collectors

    International Nuclear Information System (INIS)

    Cecal, A.; Palamaru, I.; Humelnicu, D.; Goanta, M.; Rudic, V.; Salaru, V.V.; Gulea, A.

    1997-01-01

    This paper deals with the study of bioaccumulation of uranyl ions (UO 2 2+ ) from industrial effluents, using microbiological collectors: Nostoc linkia sp., Tolipotrix sp., Spirulina sp., Porphyridium cruentum and also the glucide extract of P. cruentum. The values of retaining degree of UO 2 2+ on the biomass, for several experimental conditions, were established between 14.22 and 91.99%

  8. Surface analysis of uranyl fluoride layers with a glow discharge lamp

    International Nuclear Information System (INIS)

    Nel, J.T.; Stander, C.M.; Boehmer, R.G.

    1991-01-01

    Surface analysis with a Grimm-type glow discharge lamp was used to analyse uranyl fluoride layers that had formed on a nickel substrate after exposure to UF 6 . Narrow-band optical filters were used to isolate the intensities of three fluorine emission lines. An in-depth profile of layer composition was obtained. (author)

  9. Method of separation of uranium from contaminating ions in an aqueous feed liquid containing uranyl ions

    International Nuclear Information System (INIS)

    Sundar, P.S.; Elikan, L.; Lyon, W.L.

    1975-01-01

    A coupled cationic/anionic method for the separation of uranium from contaminated aqueous solutions which contain uranyl ions is proposed. The fluid is extracted using an organic solvent containing a reagent which, together with the uranyl ions, forms a soluble aggregate in that solvent. As an example, 0.1 - 1 Mol/l Di-2-ethyl-hexyl-phosphorous acid in kerosene is mentioned. The organic solvent is then treated with a sealing liquid (volume ratio 20 - 35). For separation, an aqueous carbonate solution or a sulfuric acid solution can be used; the most favorable pH-values and concentrations for both cases are mentioned. The U +4 -ion at the sulfuric acid separation is subsequently oxidized to the uranyl ion with air. In each case, an extraction with an amine follows; after that, the amine is separated using an ammonium-carbonate solution and the uranium aggregate is precipitated, for example as ammonium uranyl tricarbonate, and then further processed to uranium oxide. The solvents and fluids used are led back in closed circuit; a flow diagram is given. (UWI) [de

  10. Complexes of uranyl with N-oxides of heterocyclic amines. Electron-vibrational absorption spectra

    International Nuclear Information System (INIS)

    Jezowska-Trzebiatowska, B.; Wieczorek, M.

    1977-01-01

    A number of coordination compounds formed by uranyl chloride and nitrate with N-oxides of heterocyclic amines have been prepared and characterized by spectral measurements in the absorption region 20000-50000 cm -1 . The electrons and vibronic transitions have been determined and discussed. (author)

  11. Kinetic investigation of uranyl-uranophile complexation. 1. Macrocyclic kinetic effect and macrocyclic protection effect

    International Nuclear Information System (INIS)

    Tabushi, I.; Yoshizawa, A.

    1986-01-01

    Equilibria and rates of ligand-exchange reactions between uranyl tricarbonate and dithiocarbamates and between uranyl tris-(dithiocarbamates) and carbonate were studied under a variety of conditions. The dithiocarbamates used were acyclic diethyl-dithiocarbamate and macrocyclic tris(dithiocarbamate). The acyclic ligand showed a triphasic (successive three-step) equilibrium with three different equilibrium constants while the macrocyclic ligand showed a clear monophasic (one-step) equilibrium with a much larger stability constant for the dithiocarbamate-uranyl complex. The macrocyclic ligand showed the S/sub N/2-type ligand-exchange rate in the forward as well as reverse process, while the first step of the acyclic ligand-exchange reaction proceeded via the S/sub N/1-type mechanism. This kinetic macrocyclic effect on molecularity is interpreted as the result of a unique topological requirement of uranyl complexation. The macrocyclic ligand also exhibited a clear protection effect, leading to the large stability constant. 19 references, 10 figures, 2 tables

  12. Cyclic phosphopeptides to rationalize the role of phosphoamino acids in uranyl binding to biological targets

    Energy Technology Data Exchange (ETDEWEB)

    Starck, Matthieu; Laporte, Fanny A.; Oros, Stephane; Sisommay, Nathalie; Gathu, Vicky; Lebrun, Colette; Delangle, Pascale [INAC/SyMMES, UMR5819, Universite Grenoble Alpes, CEA, CNRS, Grenoble (France); Solari, Pier Lorenzo [Synchrotron SOLEIL, L' orme des Merisiers, Saint-Aubin, Gif-sur-Yvette (France); Creff, Gaelle; Den Auwer, Christophe [Institut de Chimie de Nice, UMR7272, Universite Cote d' Azur, Nice (France); Roques, Jerome [Institut de Physique Nucleaire d' Orsay, CNRS-IN2P3, Univ. Paris-Sud, Universite Paris-Saclay (France)

    2017-04-19

    The specific molecular interactions responsible for uranium toxicity are not yet understood. The uranyl binding sites in high-affinity target proteins have not been identified yet and the involvement of phosphoamino acids is still an important question. Short cyclic peptide sequences, with three glutamic acids and one phosphoamino acid, are used as simple models to mimic metal binding sites in phosphoproteins and to help understand the mechanisms involved in uranium toxicity. A combination of peptide design and synthesis, analytical chemistry, extended X-ray absorption fine structure (EXAFS) spectroscopy, and DFT calculations demonstrates the involvement of the phosphate group in the uranyl coordination sphere together with the three carboxylates of the glutamate moieties. The affinity constants measured with a reliable analytical competitive approach at physiological pH are significantly enhanced owing to the presence of the phosphorous moiety. These findings corroborate the importance of phosphoamino acids in uranyl binding in proteins and the relevance of considering phosphoproteins as potential uranyl targets in vivo. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Nuclear fuel technology - Determination of uranium in uranyl nitrate solutions of nuclear grade quality - Gravimetric method

    International Nuclear Information System (INIS)

    2003-01-01

    This International Standard specifies a precise and accurate gravimetric method for determining the mass fraction of uranium in uranyl nitrate solutions of nuclear grade quality containing more than 100 g/kg of uranium. Non-volatile impurities influence the accuracy of the method

  14. Potential New Ligand Systems for Binding Uranyl Ions in Seawater Environments

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, John [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-12-13

    Work began this quarter on a new project involving a combined computational and biosynthetic approach to selective recognition of uranyl ion in aqueous solution. This project exploits the results of computational studies to discover new ligand classes. Synthetic studies will follow to generate target systems for uranyl binding and determination of binding constants. The process will be iterative, with results from computation informing synthesis, and vice versa. The theme of the ligand classes to be examined initially will be biologically based. New phosphonate-containing α-amino acid N-carboxyanhydride (NCA) monomers were used recently to prepare well-defined phosphonate-containing poly-peptides and block copolypeptides. Our first approach is to utilize these phosphate- and phosphonate-containing NCAs for the coordination of uranyl. The work includes the laboratory-scale preparation of a series of NCAs and the full thermodynamic and spectroscopic characterization of the resulting uranyl complexes. We are also evaluating the sequestering activity in different physiological and environmental conditions of these copolymers as well as their biodegradability.

  15. Synthesis, structural investigation and kinetic studies of uranyl(VI) unsymmetrical Schiff base complexes

    Czech Academy of Sciences Publication Activity Database

    Asadi, Z.; Asadi, M.; Zeinali, A.; Ranjkeshshorkaei, M.; Fejfarová, Karla; Eigner, Václav; Dušek, Michal; Dehnokhalaji, A.

    2014-01-01

    Roč. 126, č. 6 (2014), s. 1673-1683 ISSN 0974-3626 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : uranyl schiff base complexes * kinetic study * kinetics of thermal decomposition * X-ray crystallography * cyclic voltammetry Subject RIV: CA - Inorganic Chemistry Impact factor: 1.191, year: 2014

  16. Kinetics of thermal decomposition and kinetics of substitution reaction of nano uranyl Schiff base complexes

    Czech Academy of Sciences Publication Activity Database

    Asadi, Z.; Zeinali, A.; Dušek, Michal; Eigner, Václav

    2014-01-01

    Roč. 46, č. 12 (2014), s. 718-729 ISSN 0538-8066 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : uranyl * Schiff base * kinetics * anticancer activity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.517, year: 2014

  17. Uranyl Photocleavage of Phosphopeptides Yields Truncated C-Terminally Amidated Peptide Products

    DEFF Research Database (Denmark)

    Elnegaard, Rasmus L B; Møllegaard, Niels Erik; Zhang, Qiang

    2017-01-01

    photocleavage reaction of a tetraphosphorylated β-casein model peptide. We show that the primary photocleavage products of the uranyl-catalysed reaction are C-terminally amidated. This could be of great interest to the pharmaceutical industry, as efficient peptide amidation reactions are one of the top...

  18. Criticality parameters for uranyl nitrate or plutonium nitrate systems in tributyl phosphate/kerosine and water

    International Nuclear Information System (INIS)

    Weber, W.

    1985-01-01

    This report presents the calculated values of smallest critical masses and volumina and neutron physical parameters for uranyl nitrate (3, 4, 5% U-235) or plutonium nitrate (5% Pu-240), each in a 30 per cent solution of tributyl phosphate (TBP)/kerosine. For the corresponding nitrate-water solutions, newly calculated results are presented together with a revised solution density model. A comparison of the data shows to what extent the criticality of nitrate-TBP/kerosine systems can be assessed on the basis of nitrate-water parameters, revealing that such data can be applied to uranyl nitrate/water systems, taking into account that the smallest critical mass of uranyl nitrate-TBP/kerosine systems, up to a 5 p.c. U-235 enrichment, is by 4.5 p.c. at the most smaller than that of UNH-water solutions. Plutonium nitrate (5% Pu-240) in the TBP/kerosine solution will have a smallest critical mass of up to 7 p.c. smaller, as compared with the water data. The suitability of the computing methods and cross-sections used is verified by recalculating experiments carried out to determine the lowest critical enrichment of uranyl nitrate. The calculated results are well in agreement with experimental data. The lowest critical enrichment is calculated to be 2.10 p.c. in the isotope U-235. (orig.) [de

  19. Inhibition Mechanism of Uranyl Reduction Induced by Calcium-Carbonato Complexes

    Science.gov (United States)

    Jones, M. E.; Bargar, J.; Fendorf, S. E.

    2015-12-01

    Uranium mobility in the subsurface is controlled by the redox state and chemical speciation, generally as minimally soluble U(IV) or soluble U(VI) species. In the presence of even low carbonate concentrations the uranyl-carbonato complex quickly becomes the dominant aqueous species; they are, in fact, the primary aqueous species in most groundwaters. Calcium in groundwater leads to ternary calcium-uranyl-carbonato complexes that limit the rate and extent of U(VI) reduction. This decrease in reduction rate has been attributed to surface processes, thermodynamic limitations, and kinetic factors. Here we present a new mechanism for the inhibition of ferrous iron reduction of uranyl-carbonato species in the presence of calcium. A series of experiments under variable Ca conditions were preformed to determine the role of Ca in the inhibition of U reduction by ferrous iron. Calcium ions in the Ca2UO2(CO3)3 complex sterically prevent the interaction of Fe(II) with U(VI), in turn preventing the Fe(II)-U(VI) distance required for electron transfer. The mechanism described here helps to predict U redox transformations in suboxic environments and clarifies the role of Ca in the fate and mobility of U. Electrochemical measurements further show the decrease of the U(VI) to U(V) redox potential of the uranyl-carbonato complex with decreasing pH suggesting the first electron transfer is critical determining the rate and extent of uranium reduction.

  20. The final effect ef extraction system in the uranyl nitrate-water-diethyl ether; El efecto final de la extraccion en el sistema nitro de uranilo-eter dietilico-agua

    Energy Technology Data Exchange (ETDEWEB)

    Perez Luina, A; Gutierrez Jodra, L; Miro, A R

    1957-07-01

    The solute transfer of uranyl nitrate from diallylether to water has been studied in a spray column using water as dispersed phase and a direction of extraction from ether to water. The column is 102 cm. long has a diameter of 4. 7 cm. The entrances of the phases are 7 7 cm. apart. The rates of flow of both phases have been used as variables and the concentration of the continuous phase has been determined; at different heights. The curves of logarithm of concentration of the continuous phase vs , distance to interphase show the presence of a drop of concentration in the entrance of the continuous phase. This depends on the rates of flow of the phases. No effect in the entrance of the dispersed phase has been found. (Author)

  1. Effect of sonochemical synthesized TiO2 nanoparticles and coagulation bath temperature on morphology, thermal stability and pure water flux of asymmetric cellulose acetate membranes prepared via phase inversion method

    Directory of Open Access Journals (Sweden)

    Abedini Reza

    2012-01-01

    Full Text Available In this study, asymmetric pure CA and CA/ TiO2 composite membranes were prepared via phase inversion by dispersing TiO2 nanopaticles in the CA casting solutions induced by immersion precipitation in water coagulation bath. TiO2 nanoparticles, which were synthesized by the sonochemical method, were added into the casting solution with different concentrations. Effects of TiO2 nanoparticles concentration (0 wt. %, 5wt.%, 10wt.%, 15wt.%, 20wt.% and 25wt.% and coagulation bath temperature (CBT= 25°C, 50°C and 75°C on morphology, thermal stability and pure water flux (PWF of the prepared membranes were studied and discussed. Increasing TiO2 concentration in the casting solution film along with higher CBT resulted in increasing the membrane thickness, water content (WC, membrane porosity and pure water flux (PWF, also these changes facilitate macrovoids formation. Thermal gravimetric analysis (TGA shows that thermal stability of the composite membranes were improved by the addition of TiO2 nanopaticles. Also TGA results indicated that increasing CBT in each TiO2 concentration leads to the decreasing of decomposition temperature (Td of hybrid membranes.

  2. Hybrid molecularly imprinted polymers synthesized with 3-aminopropyltriethoxysilane-methacrylic acid monomer for miniaturized solid-phase extraction: A new and economical sample preparation strategy for determination of acyclovir in urine.

    Science.gov (United States)

    Yan, Hongyuan; Wang, Mingyu; Han, Yehong; Qiao, Fengxia; Row, Kyung Ho

    2014-06-13

    The miniaturized molecularly imprinted solid-phase extraction (mini-MISPE) coupled with high-performance liquid chromatography was proposed for the determination of acyclovir in urine. 1.5-mL tapered plastic centrifuge tube filled with hybrid molecularly imprinted polymers (HMIPs) was used as the cartridge of mini-MISPE, and the HMIPs synthesized with 3-aminopropyltriethoxy silane-methacrylic acid as monomer exhibited good recognition and selectivity for acyclovir. Under the optimized condition, good linear calibration was obtained in a range of 0.5-15μgmL(-1) with the correlation coefficient of 0.9994, and the recoveries at three spiked levels were 91.6-103.3% in urine with the relative standard deviation (RSD) of ≤3.5%. Excellent intra-day and inter-day repeatability were achieved with RSD of ≤2.6% and 4.0% in three different concentrations. This method combined the advantages of HMIPs and mini-MISPE, and it could become an alternative tool for analyzing the residues of acyclovir in complex urine matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Structural, optical, and redox properties of lamellar solids derived from copper(I) complexes and n-butylammonium uranyl phosphate and arsenate

    International Nuclear Information System (INIS)

    Jacob, A.T.; Ellis, A.B.

    1989-01-01

    A family of hydrated, layered solids has been prepared from intercalative ion-exchange reactions of n-butylammonium uranyl phosphate (BAUP) or arsenate (BAUAs), (n-C 4 H 9 NH 3 )UO 2 EO 4 ·3H 2 O (E = P, As), with Cu(LL) 2 + complexes (LL is dmp = 2,9-dimethyl-1,10-phenanthroline or bcp = 2,9-dimethyl-4,7-dipheyl-1,10-phenanthroline). The products obtained were analyzed as having compositions [Cu(LL) 2 ] x [BA] 1-x UO 2 EO 4 ·2H 2 O with x ∼ 0.2. X-ray powder diffraction data reveal that the compounds are single phases that can be indexed on the basis of a tetragonal unit cell. The solids exhibit absorption and photoluminescence (PL) properties characteristic of the Cu(LL) 2 + species; the Cu(I) complexes completely quench the uranyl PL. Once intercalated, the Cu(I) complexes can be oxidized by using Br 2 vapor and rereduced either by photochemical means or by N 2 H 4 vapor, as shown by changes in electronic and EPR spectra. 37 refs., 7 figs., 2 tabs

  4. Observation of Radiolytic Field Alteration of the Uranyl Cation in Bicarbonate Solution

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Lanee A.; McNamara, Bruce K.; Sinkov, Sergey I.; Cho, Herman M.; Friese, Judah I.

    2006-12-01

    In previous work we demonstrated that radiolysis of uranyl tris carbonate in near neutral pH to alkaline carbonate solutions, could be followed by 13C NMR. Radiolysis of the complex produced novel uranyl peroxo carbonate solution state species, whose structures depended on the pH and radiolytic dose rate. In this work, we investigate speciation of the uranyl carbonate trimer which is predominant in bicarbonate solution near pH 5.9. We observe radiolytically derived speciation to different mixed peroxy carbonate species than seen in the higher pH solutions. Auto radiolysis of uranium (VI) carbonate solutions between pH 5.9 and 7.2 is shown to alter the uranium speciation over relatively short periods of time and was followed by 13C NMR and visible spectrophotometry, using dissolved 233(UO2)3(CO3)6 6- both as the radiolysis source (D= 14.9 Gy/hr) and as a trap for the newly formed hydrogen peroxide. Direct addition of hydrogen peroxide to solutions of the uranyl-carbonate trimer is shown to reproduce the 13 C NMR signatures of the complexe(s) formed by radiolysis, but additionally a variety of new complexes are revealed. Ratios of H2O2/trimer < 1.5 produced a uranyl peroxo carbonate adduct, that is shown to be common to the radiolytically produced species. Ratios of H2O2/ trimer >1 resulted in formation of stable higher order peroxo carbonate complexes. The 13C NMR signatures and visible spectra of these complexes are described here. Rigorous characterization of the species is an ongoing effort.

  5. Corrosion evaluation of uranyl nitrate solution evaporator and denitrator in Tokai reprocessing plant

    International Nuclear Information System (INIS)

    Yamanaka, Atsushi; Hashimoto, Kowa; Uchida, Toyomi; Shirato, Yoji; Isozaki, Toshihiko; Nakamura, Yoshinobu

    2011-01-01

    The Tokai reprocessing plant (TRP) adopted the PUREX method in 1977 and has reprocessed spent nuclear fuel of 1140 tHM (tons of heavy metals) since then. The reprocessing equipment suffers from various corrosion phenomena because of high nitric acidity, solution ion concentrations, such as uranium, plutonium, and fission products, and temperature. Therefore, considering corrosion performance in such a severe environment, stainless steels, titanium steel, and so forth were employed as corrosion resistant materials. The severity of the corrosive environment depends on the nitric acid concentration and the temperature of the solution, and uranium in the solution reportedly does not significantly affect the corrosion of stainless steels and controls the corrosion rates of titanium steel. The TRP equipment that handles uranyl nitrate solution operates at a low nitric acid concentration and has not experienced corrosion problems until now. However, there is a report that corrosion rates of some stainless steels increase in proportion to rising uranium concentrations. The equipment that handles the uranyl nitrate solution in the TRP includes the evaporators, which concentrate uranyl nitrate to a maximum concentration of about 1000 gU/L (grams of uranium per liter), and the denitrator, where uranyl nitrate is converted to UO 3 powder at about 320degC. These equipments are therefore required to grasp the degree of the progress of corrosion to handle high-temperature and high-concentration uranyl nitrate. The evaluation of this equipment on the basis of thickness measurement confirmed only minor corrosion and indicated that the equipment would be fully adequate for future operation. (author)

  6. Partitioning of uranyl between ferrihydrite and humic substances at acidic and circum-neutral pH

    Science.gov (United States)

    Dublet, Gabrielle; Lezama Pacheco, Juan; Bargar, John R.; Fendorf, Scott; Kumar, Naresh; Lowry, Gregory V.; Brown, Gordon E.

    2017-10-01

    As part of a larger study of the reactivity and mobility of uranyl (U(VI)O22+) cations in subsurface environments containing natural organic matter (NOM) and hydrous ferric oxides, we have examined the effect of reference humic and fulvic substances on the sorption of uranyl on 2-line ferrihydrite (Fh), a common, naturally occurring nano-Fe(III)-hydroxide. Uranyl was reacted with Fh at pH 4.6 and 7.0 in the presence and absence of Elliott Soil Humic Acid (ESHA) (0-835 ppm) or Suwanee River Fulvic Acid (SRFA) (0-955 ppm). No evidence was found for reduction of uranyl by either form of NOM after 24 h of exposure. The following three size fractions were considered in this study: (1) ≥0.2 μm (Fh-NOM aggregates), (2) 0.02-0.2 μm (dispersed Fh nanoparticles and NOM macro-molecules), and (3) <0.02 μm (dissolved). The extent to which U(VI) is sorbed in aggregates or dispersed as colloids was assessed by comparing U, Fe, and NOM concentrations in these three size fractions. Partitioning of uranyl between Fh and NOM was determined in size fraction (1) using X-ray absorption spectroscopy (XAS). Uranyl sorption on Fh-NOM aggregates was affected by the presence of NOM in different ways depending on pH and type of NOM (ESHA vs. SRFA). The presence of ESHA in the uranyl-Fh-NOM ternary system at pH 4.6 enhanced uranyl uptake more than the presence of SRFA. In contrast, neither form of NOM affected uranyl sorption at pH 7.0 over most of the NOM concentration range examined (0-500 ppm); at the highest NOM concentrations (500-955 ppm) uranyl uptake in the aggregates was slightly inhibited at pH 7.0, which is interpreted as being due to the dispersion of Fh aggregates. XAS at the U LIII-edge was used to characterize molecular-level changes in uranyl complexation as a result of sorption to the Fh-NOM aggregates. In the absence of NOM, uranyl formed dominantly inner-sphere, mononuclear, bidentate sorption complexes on Fh. However, when NOM concentration was increased at pH 4.6, the

  7. Souper: A Synthesizing Superoptimizer

    OpenAIRE

    Sasnauskas, Raimondas; Chen, Yang; Collingbourne, Peter; Ketema, Jeroen; Lup, Gratian; Taneja, Jubi; Regehr, John

    2017-01-01

    If we can automatically derive compiler optimizations, we might be able to sidestep some of the substantial engineering challenges involved in creating and maintaining a high-quality compiler. We developed Souper, a synthesizing superoptimizer, to see how far these ideas might be pushed in the context of LLVM. Along the way, we discovered that Souper's intermediate representation was sufficiently similar to the one in Microsoft Visual C++ that we applied Souper to that compiler as well. Shipp...

  8. The key role of U{sub 28} in the aqueous self-assembly of uranyl peroxide nanocages

    Energy Technology Data Exchange (ETDEWEB)

    Falaise, Clement; Nyman, May [Energy Frontier Research Center, Materials Science of Actinides, Department of Chemistry, Oregon State University, Corvallis, OR (United States)

    2016-10-04

    For 11 years now, the structural diversity and aesthetic beauty of uranyl-peroxide capsules have fascinated researchers from the diverse fields of mineralogy, polyoxometalate chemistry, and nuclear fuel technologies. There is still much to be learned about the mechanisms of the self-assembly process, and the role of solution parameters including pH, alkali template, temperature, time, and others. Here we have exploited the high solubility of the UO{sub 2}{sup 2+}/H{sub 2}O{sub 2}/LiOH aqueous system to address the effect of the hydroxide concentration. Important techniques of this study are single-crystal X-ray diffraction, small-angle X-ray scattering, and Raman spectroscopy. Three key phases dominate the solution speciation as a function of time and the LiOH/UO{sub 2}{sup 2+} ratio: the uranyl-triperoxide monomer [UO{sub 2}(O{sub 2}){sub 3}]{sup 4-}and the two capsules [(UO{sub 2})(O{sub 2})(OH)]{sub 24}{sup 24-}(U{sub 24}) and [(UO{sub 2})(O{sub 2}){sub 1.5}]{sub 28}{sup 28-}(U{sub 28}). When the LiOH/U ratio is around three, U{sub 28} forms rapidly and this cluster can be isolated in high yield and purity. This result was most surprising and challenges the hypothesis that alkali templating is the most important determinant in the cluster geometry. Moreover, analogous experiments with KOH, NH{sub 4}OH, and TEAOH (TEA=tetraethylammonium) also rapidly yield U{sub 28}, which suggests that U{sub 28} is the kinetically favored species. Complete mapping of the pH-time phase space reveals only a narrow window of the U{sub 28} dominance, which is why it was previously overlooked as an important kinetic species in this chemical system, as well as others with different counterions. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Kinetic studies of uranyl ion adsorption on acrylonitrile (AN)/polyethylene glycol (PEG) interpenetrating networks (IPN)

    International Nuclear Information System (INIS)

    Aycik, G.A.; Gurellier, R.

    2004-01-01

    Full text: The kinetics of the adsorption of uranyl ions on amidoximated acrylonitrile (AN)/ polyethylene glycol (PEG) interpenetrating network (IPNs) from aqueous solutions was studied as a function of time and temperature. The IPNs were prepared by irradiation initiated gamma polymerisation using Co-60 gamma source. Adsorption capacities were performed for definite uranyl ion concentrations of 1x10 -2 M and at four different temperatures as 290K, 298K, 308K and 318K by gamma spectrometer. Adsorption time was increased from zero to 48 hours. The results indicate that adsorption capacity increases linearly with increasing temperature. Temperature and agitation hardly influence equilibrium and kinetics and decreasing of temperature results in a slightly greater time to reach equilibrium. The adsorption of uranyl ions has been studied in a multi step mechanism processes thus comparing chemical sorption and diffusion sorption processes. The experimental data was analysed using various kinetic models to determine the best-fit equation for the adsorption mechanisms. However, it was shown that all models, in general according to the reaction time and uranyl ion concentration in the solution, could describe the adsorption of uranyl ion onto amidoximated IPN, the adsorption kinetics was best described by zeroth order and intraparticle diffusion model whereas that of in increasing time by pseudo first and pseudo second order response respectively. External-intraparticle diffusion and zeroth order process in the IPN structure is proposed as a mass transfer mechanism and the results indicate a diffusion-controlled process. The Mean Activation Energy Of Uranyl Ions Adsorption Was Found As 4,1 Kj/Mole By Using Arrhenius Equation. The Rate Constant, The Equilibrium Adsorption Capacity And The Initial Adsorption Rate Were Calculated For All Models At Each Temperature. Kinetic Parameters Of All Models And The Normalized Standard Deviations Between The Measured And Predicted

  10. SYNTHESIZER CONTROLLED BEAM TRANSFER FROM THE AGS TO RHIC

    International Nuclear Information System (INIS)

    DELONG, J.; BRENNAN, J.M.; FISCHER, W.; HAYES, T.; SMITH, K.; VALENTINO, S.

    2001-01-01

    To ensure minimal losses and to preserve longitudinal emittance, beam is transferred from the AGS to the RHIC bunch to bucket. This requires precision frequency and phase control for synchronization and kicker timing. The required precision is realized with a set of Direct Digital Synthesizers. Each synthesizer can be frequency and phase modulated to align the AGS bunch to the target bucket in the RHIC phase

  11. Isolation of a star-shaped uranium(V/VI) cluster from the anaerobic photochemical reduction of uranyl(VI)

    International Nuclear Information System (INIS)

    Chatelain, Lucile; White, Sarah; Scopelliti, Rosario; Mazzanti, Marinella

    2016-01-01

    Actinide oxo clusters are an important class of compounds due to their impact on actinide migration in the environment. The photolytic reduction of uranyl(VI) has potential application in catalysis and spent nuclear fuel reprocessing, but the intermediate species involved in this reduction have not yet been elucidated. Here we show that the photolysis of partially hydrated uranyl(VI) in anaerobic conditions leads to the reduction of uranyl(VI), and to the incorporation of the resulting U V species into the stable mixed-valent star-shaped U VI /U V oxo cluster [U(UO 2 ) 5 (μ 3 -O) 5 (PhCOO) 5 (Py) 7 ]. This cluster is only the second example of a U VI /U V cluster and the first one associating uranyl groups to a non-uranyl(V) center. The U V center in 1 is stable, while the reaction of uranyl(V) iodide with potassium benzoate leads to immediate disproportionation and formation of the U 12 IV U 4 V O 24 cluster {[K(Py) 2 ] 2 [K(Py)] 2 [U 16 O 24 (PhCOO) 24 (Py) 2 ]}.

  12. Reactive transport of uranyl: fixation mode on silica and goethite; experiments in columns and closed reactors; simulations

    International Nuclear Information System (INIS)

    Gabriel, U.

    1998-01-01

    Uranium contaminated areas are found in mine waste disposal sites, former military areas, etc. The present study focuses on the identification or mechanisms which may lead contaminated soils to become a sudden potential threat to surface and ground waters. Mechanisms were studied on model material at two levels. On the molecular scale, the complexation of uranyl at trace metal concentrations was investigated with amorphous silica. Complexation is shown to occur via the formation of surface complexes, characterised by different time-resolved laser-induced luminescence spectra and life times and stoichiometry. On the macro-scale the transport behaviour of uranyl in a cristobalite-goethite-carbonate-uranyl system was investigated with laboratory column and batch experiments. Uranium mobility was found to be controlled by the interaction between physical transport and a reversible, rate-controlled, fixation reaction. Sorption was shown to be an ensemble of competing solution and surface complexation reactions, leading to an apparent non-linear (Langmuir-like) adsorption isotherm. Finally the impact of a sudden change in background geochemistry was studied. Conditions leading to a dramatic mobilization of uranium from mildly contaminated systems were experimentally identified. Maximal uranyl concentration are controlled by the total extractable uranyl in the system and limited by uranyl solubility. Evolution of the background geochemical conditions is thus an important part of contaminated sites risk assessment. (author)

  13. Production of U3O8 by uranyl formate precipitation and calcination in a full-scale pilot facility

    International Nuclear Information System (INIS)

    Kendrick, L.S.; Wilson, W.A.; Mosley, W.C.

    1984-08-01

    The uranyl formate process for the production of U 3 O 8 with a controlled particle size has been extensively studied on a laboratory scale. Based on this study, a pilot-scale facility (the Uranyl Formate Facility) was built to investigate the key steps of the process on a larger scale. These steps were the precipitation of a uranyl formate monohydrate salt and the calcination of this salt to U 3 O 8 . Tests of the facility and process were conducted at conditions recommended by the laboratory-scale studies for a full-scale production facility. These tests demonstrated that U 3 O 8 of the required particle size for the PM process can be produced on a plant scale by the calcination of uranyl formate crystals. The performance of the U 3 O 8 produced by the uranyl formate process in fuel tube fabrication was also investigated. Small-scale extrusion tests of U 3 O 8 -Al cores which used the U 3 O 8 produced in the Uranyl Formate Facility were conducted. These tests demonstrated that the U 3 O 8 quality was satisfactory for the PM process

  14. Determination of the stability of the uranyl ion sipped in τ-hydrogen phosphate of zirconium in sodic form

    International Nuclear Information System (INIS)

    Ordonez R, E.; Fernandez V, S.M.; Drot, R.; Simoni, E.

    2005-01-01

    The stability of the uranyl sipped in the zirconium τ-hydrogen phosphate in sodic form (τ-NaZrP), was carried out characterizing the complexes formed by Laser spectroscopy in the visible region and by X-ray photoelectron spectroscopy. The material was prepared by a new synthesis technique working in nitrogen atmosphere and to low temperatures. The sorption of the uranyl ion was made in acid media with concentrations of 10 -4 and 10 -5 of uranyl nitrate and with ion forces of 0.1 and 0.5 M of NaClO 4 . The spectra of induced fluorescence with laser (TRLFS) show that the uranyl is fixed in very acid media in three well differentiated species, to pH less acid, the specie of long half life disappears and are only those of short half life. The results of the binding energy obtained by XPS indicate that the binding energy of the uranyl confer it a stable character to the complex formed in the τ-NaZP, that makes to this material appropriate to retain to the uranyl in solution to high ion forces and in acid media. (Author)

  15. Isolation of a star-shaped uranium(V/VI) cluster from the anaerobic photochemical reduction of uranyl(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Chatelain, Lucile; White, Sarah; Scopelliti, Rosario; Mazzanti, Marinella [Ecole Polytechnique Federale de Lausanne (EPFL) (Switzerland). Inst. de Sciences et Ingenierie Chimiques

    2016-11-07

    Actinide oxo clusters are an important class of compounds due to their impact on actinide migration in the environment. The photolytic reduction of uranyl(VI) has potential application in catalysis and spent nuclear fuel reprocessing, but the intermediate species involved in this reduction have not yet been elucidated. Here we show that the photolysis of partially hydrated uranyl(VI) in anaerobic conditions leads to the reduction of uranyl(VI), and to the incorporation of the resulting U{sup V} species into the stable mixed-valent star-shaped U{sup VI}/U{sup V} oxo cluster [U(UO{sub 2}){sub 5}(μ{sub 3}-O){sub 5}(PhCOO){sub 5}(Py){sub 7}]. This cluster is only the second example of a U{sup VI}/U{sup V} cluster and the first one associating uranyl groups to a non-uranyl(V) center. The U{sup V} center in 1 is stable, while the reaction of uranyl(V) iodide with potassium benzoate leads to immediate disproportionation and formation of the U{sub 12}{sup IV}U{sub 4}{sup V}O{sub 24} cluster {[K(Py)_2]_2[K(Py)]_2[U_1_6O_2_4(PhCOO)_2_4(Py)_2]}.

  16. Uranyl complexes as scaffolding or spacers for cucurbit[6]uril molecules in homo- and heterometallic species, including a uranyl-lanthanide complex

    Energy Technology Data Exchange (ETDEWEB)

    Thuery, Pierre [NIMBE, CEA, CNRS, Universite Paris-Saclay, CEA Saclay, Gif-sur-Yvette (France)

    2017-06-16

    The reaction of uranyl nitrate with cucurbit[6]uril (CB6) and carboxylic or sulfonic ligands under hydrothermal conditions and in the presence of additional metal cations (K{sup I} or Ce{sup III}) or cosolvents provided four complexes, which were crystallographically characterized. The compound [(UO{sub 2}){sub 2}K{sub 2}(CB6)(adc){sub 2}(NO{sub 3}){sub 2}(H{sub 2}O){sub 2}].5H{sub 2}O (1), where H{sub 2}adc is 1,3-adamantanedicarboxylic acid, crystallizes in the form of a central K{sub 2}(CB6){sup 2+} column surrounded by two one-dimensional (1D) polymeric UO{sub 2}(adc)(NO{sub 3}){sup -} chains attached to the column by nitrate bridges, with a perfect match of the repeat lengths in the two subunits. The longer 1,3-adamantanediacetic acid (H{sub 2}adac) gives the complex [(UO{sub 2}){sub 2}(adac){sub 2}(HCOOH){sub 2}].CB6.6H{sub 2}O (2), in which the 1D uranyl-containing polymer and columns of CB6 molecules form a layered arrangement held by weak CH..O hydrogen bonds. The complex formed with the dipotassium salt of methanedisulfonic acid (K{sub 2}mds), [(UO{sub 2}){sub 2}K{sub 2}(CB6)(mds){sub 2}(OH){sub 2}(H{sub 2}O){sub 8}].4H{sub 2}O (3), is a 1D polymer, in which K{sub 2}(CB6){sup 2+} units are connected to one another by doubly hydroxide-bridged uranyl dimers in which the disulfonates are terminal, chelating ligands; connection between the two subunits is solely through potassium oxo-bonding to uranyl. The complex [(UO{sub 2}){sub 2}Ce{sub 2}(CB6)(C{sub 2}O{sub 4}){sub 3}(NO{sub 3}){sub 4}(H{sub 2}O){sub 6}].2H{sub 2}O (4) is a 1D polymer containing bridging oxalate ligands formed in situ, in which CB6 is coordinated to the lanthanide cations only; one nitrate ligand and one water ligand, hydrogen-bonded to each other, are included in the CB6 cavity, with the possible occurrence of interactions between nitrate oxygen atoms and ureido carbon atoms. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. SYNTH: A spectrum synthesizer

    International Nuclear Information System (INIS)

    Hensley, W.K.; McKinnon, A.D.; Miley, H.S.; Panisko, M.E.; Savard, R.M.

    1994-07-01

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma-ray spectroscopy experiments. The code, dubbed SYNTH, allows a use r to specify physical characteristics of a gamma-ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the type and thickness of absorbers, the size and composition of the detector (Ge or NaI), and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function vs energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results will be presented

  18. SYNTH: A spectrum synthesizer

    International Nuclear Information System (INIS)

    Hensley, W.K.; McKinnon, A.D.; Miley, H.S.; Panisko, M.E.; Savard, R.M.

    1993-10-01

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma ray spectroscopy experiments. The code, dubbed SYNTH, allows a user to specify physical characteristics of a gamma ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the presence of absorbers, the type and size of the detector, and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function versus energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results are presented

  19. Thermodynamic study of uranyl sorption onto lanthanum monophosphate (LaPO4) and magnetite (Fe3O4)

    International Nuclear Information System (INIS)

    Felix, Olivia

    2012-01-01

    The migration of radio-toxic elements in the geosphere is mainly regulated by chemical parameters which control the partitioning of the elements between mineral phases and aqueous solutions. Variation in temperature may affect the retention properties of a mineral surface and requires a careful investigation in order to understand the radionuclides behavior in the geosphere. In this way, the interaction mechanisms between uranium(VI) and two minerals (LaPO 4 and Fe 3 O 4 ) have been studied. In a first step, the monazite (LaPO 4 ) has been chosen as methodological solid in order to clearly define all the different stages needed to completely characterize the influence of temperature on the sorption phenomena. To reach that goal, three media, more or less complexants towards aqueous uranyl and the mineral surface, have been considered. Physico-chemical as well as surface acid-base properties of the solid surface have been studied by considering three electrolytes (NaClO 4 , NaNO 3 and Na 2 SO 4 ) and temperatures ranged from 25 C to 95 C. The point of zero charge has been found to be identical for perchlorate and nitrate media (pH PZC =2.1) but it was found to be one pK unit higher for the sulfate medium indicating a sorption of the background electrolyte ions. The reaction heats associated to the hydration of the solid have been measured by using microcalorimetry and the nature of the reactive surface sites has been determined by carrying out Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS). On the basis of these experimental constraints, the titration curves obtained for the monazite suspensions were fitted by using the Constant Capacitance Model and the 1-pK model was preferred to characterize the surface charge evolution, due to the limited number of adjustable parameters. The surface protonation constants being determined, the behavior of U(VI) towards the monazite surface in the three electrolytes has been investigated. On the basis of both U

  20. Water structure and aqueous uranyl(VI) adsorption equilibria onto external surfaces of beidellite, montmorillonite, and pyrophyllite: results from molecular simulations.

    Science.gov (United States)

    Greathouse, Jeffery A; Cygan, Randall T

    2006-06-15

    Molecular dynamics simulations were performed to provide a systematic study of aqueous uranyl adsorption onto the external surface of 2:1 dioctahedral clays. Our understanding of this key process is critical in predicting the fate of radioactive contaminants in natural groundwaters. These simulations provide atomistic detail to help explain experimental trends in uranyl adsorption onto natural media containing smectite clays. Aqueous uranyl concentrations ranged from 0.027 to 0.162 M. Sodium ions and carbonate ions (0.027-0.243 M) were also present in the aqueous regions to more faithfully model a stream of uranyl-containing groundwater contacting a mineral system comprised of Na-smectite. No adsorption occurred near the pyrophyllite surface, and there was little difference in uranyl adsorption onto the beidellite and montmorillonite, despite the difference in location of clay layer charge between the two. At low uranyl concentration, the pentaaquouranyl complex dominates in solution and readily adsorbs to the clay basal plane. At higher uranyl (and carbonate) concentrations, the mono(carbonato) complex forms in solution, and uranyl adsorption decreases. Sodium adsorption onto beidellite occurred both as inner- and outer-sphere surface complexes, again with little effect on uranyl adsorption. Uranyl surface complexes consisted primarily of the pentaaquo cation (85%) and to a lesser extent the mono(carbonato) species (15%). Speciation diagrams of the aqueous region indicate that the mono(carbonato)uranyl complex is abundant at high ionic strength. Oligomeric uranyl complexes are observed at high ionic strength, particularly near the pyrophyllite and montmorillonite surfaces. Atomic density profiles of water oxygen and hydrogen atoms are nearly identical near the beidellite and montmorillonite surfaces. Water structure therefore appears to be governed by the presence of adsorbed ions and not by the location of layer charge associated with the substrate. The water

  1. Biosensing for the Environment and Defence: Aqueous Uranyl Detection Using Bacterial Surface Layer Proteins

    Directory of Open Access Journals (Sweden)

    David J.R. Conroy

    2010-05-01

    Full Text Available The fabrication of novel uranyl (UO22+ binding protein based sensors is reported. The new biosensor responds to picomolar levels of aqueous uranyl ions within minutes using Lysinibacillus sphaericus JG-A12 S-layer protein tethered to gold electrodes. In comparison to traditional self assembled monolayer based biosensors the porous bioconjugated layer gave greater stability, longer electrode life span and a denser protein layer. Biosensors responded specifically to UO22+ ions and showed minor interference from Ni2+, Cs+, Cd2+ and Co2+. Chemical modification of JG-A12 protein phosphate and carboxyl groups prevented UO22+ binding, showing that both moieties are involved in the recognition to UO22+.

  2. Controlled deprotection and reorganization of uranyl oxo groups in a binuclear macrocyclic environment

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Guy M.; Arnold, Polly L.; Love, Jason B. [EaStCHEM School of Chemistry, University of Edinburgh (United Kingdom)

    2012-12-07

    Switching on uranium(V) reactivity: The silylated uranium(V) dioxo complex [(Me{sub 3}SiOUO){sub 2}(L){sub 2}] (A) is inert to oxidation, but after two-electron reduction to [(Me{sub 3}SiOUO){sub 2}(L)]{sup 2-} (1), it can be desilylated to form [OU(μ-O){sub 2}UO(L){sub 2}]{sup 2-} (2) with reinstated uranyl character. Removal of the silyl group uncovers new redox and oxo rearrangement chemistry for uranium, thus reforming the uranyl motif and involving the U{sup VI/V} couple in dioxygen reduction. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Interaction of uranyl ions with snake venom proteins from Lachesis muta muta

    International Nuclear Information System (INIS)

    MacCordick, H.J.; Taghva, F.

    1997-01-01

    The reaction product of uranyl nitrate with whole-protein Bushmaster snake venom in nitrate buffer at pH 3.5 has been studied. The maximum uptake of uranium was 291 μmol U x g -1 of venom. The infrared spectrum of the product showed an asymmetric O-U-O vibration at 921 cm -1 typical of complex formation with the uranyl ion. Stability measurements with the UO 2 2+ -protein complex in neutral medium indicated moderate hydrolytic stability, with 14% dissociation after 16 hours at 0 deg C. Neutron irradiation and desorption studies with a 235 U-labelled complex showed that generated fission products such as lanthanides and barium were readily lixiviated at pH 7, whereas Ru and Zr were highly retained by the protein substrate. (author)

  4. Thermometric titration of a free acid and of uranyl in spent fuel element solutions

    International Nuclear Information System (INIS)

    Zamek, M.; Strafelda, F.

    1975-01-01

    A method was elaborated of determining nitric acid in the presence of uranyl nitrate in both aqueous and non-aqueous solutions using a pyridine aqueous solution as a titration agent, and of determining excess uranyl after a hydrogen peroxide addition by a further titration using the same agent. Even a hundred-fold excess of magnesium did not disturb the titration. The method is used in operating solution analyses in the extraction fuel reprocessing in the presence of a small amount of plutonium and of fission products. The reproducibility and accuracy of the method varied in the order of tens to units per cent depending on the concentration of components to be determined. The procedure is applicable for test volumes ranging between 0.1 and 10 ml in concentrations of 1 to 10 -3 M. (author)

  5. Obtention of Uo3 by means of denitration of uranyl nitrate in a fluidized-bed

    International Nuclear Information System (INIS)

    Santos, W.R. dos; Costa, P.A.

    1990-01-01

    A fluidized-bed pilot unit for the production of UO 3 installed at IPEN-CNEN/SP is described. Its capacity is of 20 kg U/h in a continuous process. The main components of this pilot unit are: a system for the concentration of nuclearly pure uranyl nitrate (≅ 100 g U/L), a system for the denitration of the concentrated uranyl nitrate, an absorption system for NO 2 produced during the denitration reaction and, finally, a system for the dissolution of UO 3 that does not meet the specifications. The operational troubles found during the initial runs are presented. The results of the physical and chemical analysis of the UO 3 produced are discussed and a comparison is made for the UO 3 obtained by both fluidized-bed and wet processes. (author) [pt

  6. PVC membrane based potentiometric sensor for uranyl ion using thenoyl trifluoro acetone as ionophore

    International Nuclear Information System (INIS)

    Nanda, D.; Chouhan, H.P.S.; Maiti, B.

    2004-01-01

    Uranyl ion selective electrode based on thenoyl trifluoro acetone (TTA) incorporated into a polyvinyl chloride (PVC) membrane has been developed where dibutyl phthalate and sodium tetraphenyl borate have been used as plasticizer and anion excluder respectively. The PVC membrane containing the active ionophore, TTA, and the other ingredients has been directly cast a graphite electrode. The electrode shows near Nernstian response to UO 2 2+ in the concentration range of 10 -1 to 10 -6 mol. L -1 an average slope of 30 mV/decade. Alkali and alkaline earth ions do not interfere with the determination of uranyl ion. Interference of transition metal ions and Th (IV) is eliminated using EDTA. (author)

  7. Crystallization characteristics of ammonium uranyl carbonate (AUC) in ammonium carbonate solutions

    International Nuclear Information System (INIS)

    Kim, T.J.; Jeong, K.C.; Park, J.H.; Chang, I.S.; Choi, C.S.

    1994-01-01

    Ammonium carbonate solutions with an excessive amount of NH 3 were produced in a commercial AUC (ammonium uranyl carbonate) conversion plant. In this study the AUC crystals, precipitated with uranyl nitrate and ammonium carbonate solutions prepared in the laboratory, were characterized to determine the feasibility of recycling ammonium carbonate solution. The AUC crystals were easily agglomerated with the increasing concentration of CO 3 2- and mole ratio of NH 4 + /CO 3 2- in ammonium carbonate solution. Effects of a mixing system for the solution in the AUC crystallizer and the feed location of the solution onthe agglomeration of AUC crystals were also studied along with the effects of agglomerated AUC powders on UO 2 powders. Finally, the feasibility of manufacturing UO 2 fuel with a sintered pellet density of 10.52 g/cm 3 , using the AUC powders generated in this experiment, was demonstrated. (orig.)

  8. Temperature effect on life-time of electron-excited uranyl ion. III. Effect of deuteration of solvent

    International Nuclear Information System (INIS)

    Lotnik, S.V.; Khamidullina, L.A.; Kazakov, V.P.

    2001-01-01

    Effect of deuteration of solvent was detected. The effect appeared in significant difference of shape of curves of uranyl ion (UO 2 2+ )* life-time temperature dependences in electron-excited state (τ). The curves were plotted during heating of frozen up to 77 K H 2 SO 4 solutions in H 2 O and D 2 SO 4 solutions in D 2 O. It was shown that in the case of D 2 SO 4 τ value in glass-like solution was lower then in polycrystalline sample, whereas in frozen H 2 SO 4 solutions there was opposite picture. Detected isotope effect was explained just as different proceeding of phase transition in H 2 SO 4 and D 2 SO 4 solutions so significant decrease of probability of nonradiating deactivation of (UO 2 2+ )* absorbed on D 2 SO 4 ·4D 2 O crystallohydrate surface in comparison with (UO 2 2+ )* absorbed on H 2 SO 4 ·4H 2 O and H 2 SO 4 ·6.5H 2 O crystallohydrate surfaces [ru

  9. Novel two-dimensional uranyl-organic assemblages in the citrate and D(-)-citramalate families

    International Nuclear Information System (INIS)

    Thuery, P.

    2008-01-01

    Uranyl nitrate reacts with D(-)-citramalic acid (H(3)citml) under mild hydrothermal conditions to give the two-dimensional polymer [UO 2 (Hcitml)] 1, in which each ligand chelates one metal atom through its hydroxyl and alpha- carboxylate groups and binds to three others in monodentate fashion. The resulting neutral layers display isolated uranyl pentagonal bipyramidal polyhedra. Whereas citric acid (H(4)cit) has been shown previously to give various three- and mono-dimensional uranyl organic assemblages, complexation under hydrothermal conditions in the presence of either NaOH/NEt 4 Cl or pyridine yields the complexes [NEt 4 ] 2 [(UO 2 ) 3 (cit) 2 (H 2 O) 2 ]· 2H 2 O 2 and [Hpy] 2 )[(UO 2 ) 3 (cit)(Hcit)(OH)] 3, respectively, which both crystallize as two- dimensional frameworks. The layers are either planar and separated by the counter ions in 2 or corrugated and hydrogen bonded to one another in 3. In both 2 and 3, [UO 2 (cit)] 2 4- dimeric subunits with edge-sharing pentagonal bipyramidal uranium coordination polyhedra are present but, in both cases and in contrast with previous structures containing [UO 2 (Hcit)] 2 2- dimers, the carboxylate group not involved in the dimer formation is coordinated to another uranyl unit, which is part of either a centrosymmetric hexagonal bipyramidal bis-aquated group or a different, [(UO 2 ) 2 (Hcit)(OH)] dimer. These examples of two- dimensional assemblages further illustrate the variety of architectures which can be obtained with citric and related acids and the important structure-directing effects of the counter ions. (author)

  10. Removal of toxic uranium from synthetic nuclear power reactor effluents using uranyl ion imprinted polymer particles.

    Science.gov (United States)

    Preetha, Chandrika Ravindran; Gladis, Joseph Mary; Rao, Talasila Prasada; Venkateswaran, Gopala

    2006-05-01

    Major quantities of uranium find use as nuclear fuel in nuclear power reactors. In view of the extreme toxicity of uranium and consequent stringent limits fixed by WHO and various national governments, it is essential to remove uranium from nuclear power reactor effluents before discharge into environment. Ion imprinted polymer (IIP) materials have traditionally been used for the recovery of uranium from dilute aqueous solutions prior to detection or from seawater. We now describe the use of IIP materials for selective removal of uranium from a typical synthetic nuclear power reactor effluent. The IIP materials were prepared for uranyl ion (imprint ion) by forming binary salicylaldoxime (SALO) or 4-vinylpyridine (VP) or ternary SALO-VP complexes in 2-methoxyethanol (porogen) and copolymerizing in the presence of styrene (monomer), divinylbenzene (cross-linking monomer), and 2,2'-azobisisobutyronitrile (initiator). The resulting materials were then ground and sieved to obtain unleached polymer particles. Leached IIP particles were obtained by leaching the imprint ions with 6.0 M HCl. Control polymer particles were also prepared analogously without the imprint ion. The IIP particles obtained with ternary complex alone gave quantitative removal of uranyl ion in the pH range 3.5-5.0 with as low as 0.08 g. The retention capacity of uranyl IIP particles was found to be 98.50 mg/g of polymer. The present study successfully demonstrates the feasibility of removing uranyl ions selectively in the range 5 microg - 300 mg present in 500 mL of synthetic nuclear power reactor effluent containing a host of other inorganic species.

  11. Stability and kinetics of uranyl ion complexation by macrocycles in propylene carbonate

    International Nuclear Information System (INIS)

    Fux, P.

    1984-06-01

    A thermodynamic study of uranyl ion complexes formation with different macrocyclic ligands was realized in propylene carbonate as solvent using spectrophotometric and potentiometric techniques. Formation kinetics of two UO 2 complexes: a crown ether (18C6) and a coronand (22) was studied by spectrophotometry in propylene carbonate with addition of tetraethylammonium chlorate 0.1M at 25 0 C. Possible structures of complexes in solution are discussed [fr

  12. Fabrication of ceramic grade UO2 by direct conversion of uranyl nitrate hexahydrate

    International Nuclear Information System (INIS)

    Lainetti, P.E.O.; Riella, H.G.

    1992-01-01

    A method of direct conversion of uranyl nitrate hexahydrate (UNH) solution to ceramic grade uranium dioxide powders by thermal denitration in a furnace that combines atomization nozzle and a gas stirred bed is described. The main purpose of this work is to show that this alternative process is technically viable, specially if the recovery of the scrap generated in the nuclear fuel pellet production is required, without further generation of new liquid wastes. (author)

  13. Crystal structure of the (REE)–uranyl carbonate mineral shabaite-(Nd)

    Czech Academy of Sciences Publication Activity Database

    Plášil, Jakub; Škoda, R.

    2017-01-01

    Roč. 62, č. 2 (2017), s. 97-105 ISSN 1802-6222 R&D Projects: GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : shabaite-(Nd) * uranyl carbonate * rare-earth elements * crystal structure * mineral evolution Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 0.609, year: 2016

  14. Rapid determination of fluoride in uranyl nitrate solution obtained in conversion process of uranium tetrafluoride

    International Nuclear Information System (INIS)

    Levin, R.; Feldman, R.; Sahar, E.

    1976-01-01

    In uranium production the conversion of impure uranium tetrafluoride by sodium hydroxide was chosen as a current process. A rapid method for determination of fluoride in uranyl-nitrate solution was developed. The method includes precipitation of uranium as diuranate, separation by centrifugation, and subsequent determination of fluoride in supernate by titration with thorium nitrate. Fluoride can be measured over the range 0.15-2.5 gr/gr U, with accuracy of +-5%, within 15 minutes. (author)

  15. Thermodynamic properties of actinide complexes. IV. Thorium(IV)- and uranyl(VI)-malonate systems

    Energy Technology Data Exchange (ETDEWEB)

    Di Bernardo, P; Di Napoli, V; Cassol, A; Magon, L [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi

    1977-01-01

    The stability constants and the enthalpies of formation of thorium(IV)- and uranyl(VI)-malonate complexes have been determined by potentiometric and calorimetric titrations in 1.00 M solutions of Na(ClO/sub 4/) at 25/sup 0/C. All complexes formed are found to be stabilized by a large entropy gain. The values for the stability constants agree with an ionic bonding model. The malonate behaves as a bidentate ligand forming only chelate complexes.

  16. Uranyl ion complexation by the tripodal ligand nitrilo-tri-acetate

    Energy Technology Data Exchange (ETDEWEB)

    Thuery, P. [CEA Saclay, DSM/DRECAM/SCM, F-91191 Gif Sur Yvette, (France)

    2007-07-01

    Reaction of uranyl nitrate with N-(2-acetamido)iminodiacetic acid (ADA) under hydrothermal conditions resulted in the hydrolysis of the amide group and the isolation of the complex [(UO{sub 2})(HNTA)(H{sub 2}O){sub 2}], in which each nitrilo-tri-acetate ligand, protonated at the N site, bridges three metal atoms to give rise to infinite ladder-like ribbons built from 2:2 metallacycles. (author)

  17. Selectivity in Ligand Binding to Uranyl Compounds: A Synthetic, Structural, Thermodynamic and Computational Study

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, John [Univ. of California, Berkeley, CA (United States)

    2017-12-06

    The uranyl cation (UO22+) is the most abundant form of uranium on the planet. It is estimated that 4.5 billion tons of uranium in this form exist in sea water. The ability to bind and extract the uranyl cation from aqueous solution while separating it from other elements would provide a limitless source of nuclear fuel. A large body of research concerns the selective recognition and extraction of uranyl. A stable molecule, the cation has a linear O=U=O geometry. The short U-O bonds (1.78 Å) arise from the combination of uranium 5f/6d and oxygen 2p orbitals. Due to the oxygen moieties being multiply bonded, these sites were not thought to be basic enough for Lewis acidic coordination to be a viable approach to sequestration. We believe that the goal of developing a practical system for uranium separation from seawater will not be attained without new insights into our existing fundamental knowledge of actinide chemistry. We posit that detailed studies of the kinetic and thermodynamic factors that influence interactions between f-elements and ligands with a range of donor atoms is essential to any major advance in this important area. The goal of this research is thus to broaden the coordination chemistry of the uranyl ion by studying new ligand systems via synthetic, structural, thermodynamic and computational methods. We anticipate that this fundamental science will find use beyond actinide separation technologies in areas such as nuclear waste remediation and nuclear materials.

  18. Engaging the Terminal: Promoting Halogen Bonding Interactions with Uranyl Oxo Atoms.

    Science.gov (United States)

    Carter, Korey P; Kalaj, Mark; Surbella, Robert G; Ducati, Lucas C; Autschbach, Jochen; Cahill, Christopher L

    2017-11-02

    Engaging the nominally terminal oxo atoms of the linear uranyl (UO 2 2+ ) cation in non-covalent interactions represents both a significant challenge and opportunity within the field of actinide hybrid materials. An approach has been developed for promoting oxo atom participation in a range of non-covalent interactions, through judicious choice of electron donating equatorial ligands and appropriately polarizable halogen-donor atoms. As such, a family of uranyl hybrid materials was generated based on a combination of 2,5-dihalobenzoic acid and aromatic, chelating N-donor ligands. Delineation of criteria for oxo participation in halogen bonding interactions has been achieved by preparing materials containing 2,5-dichloro- (25diClBA) and 2,5-dibromobenzoic acid (25diBrBA) coupled with 2,2'-bipyridine (bipy) (1 and 2), 1,10-phenanthroline (phen) (3-5), 2,2':6',2''-terpyridine (terpy) (6-8), or 4'-chloro-2,2':6',2''-terpyridine (Cl-terpy) (9-10), which have been characterized through single crystal X-ray diffraction, Raman, Infrared (IR), and luminescence spectroscopy, as well as through density functional calculations of electrostatic potentials. Looking comprehensively, these results are compared with recently published analogues featuring 2,5-diiodobenzoic acid which indicate that although inclusion of a capping ligand in the uranyl first coordination sphere is important, it is the polarizability of the selected halogen atom that ultimately drives halogen bonding interactions with the uranyl oxo atoms. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A bibliographical review on the radiolysis of uranyl nitrate solutions in nitric acid medium

    International Nuclear Information System (INIS)

    Siri, Sandra; Mondino, Angel V.

    2004-01-01

    A bibliographical study on the effects of ionizing radiation on uranyl nitrate solutions in nitric acid medium was performed, and the state of knowledge on this subject is presented. The main experimental and theoretical results on water, nitric acid and uranium solutions radiolysis are reviewed and critically evaluated. This paper provides a collection of references as an aid to the development of practical applications, and to stimulate new research on fundamental processes in these systems. (author) [es

  20. Crystal structure of the (REE)-uranyl carbonate mineral kamotoite-(Y)

    Czech Academy of Sciences Publication Activity Database

    Plášil, Jakub; Petříček, Václav

    2017-01-01

    Roč. 81, č. 3 (2017), s. 653-660 ISSN 0026-461X R&D Projects: GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : kamotoite-(Y) * uranyl carbonate * rare-earth elements * crystal structure Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 1.285, year: 2016

  1. Synthesis, X-ray crystallography, spectroscopy, electrochemistry, thermal and kinetic study of uranyl Schiff base complexes

    Czech Academy of Sciences Publication Activity Database

    Asadi, Z.; Golzard, F.; Eigner, Václav; Dušek, Michal

    2013-01-01

    Roč. 66, č. 20 (2013), s. 3629-3646 ISSN 0095-8972 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : X-ray crystallography * uranyl Schiff base complex * kinetics of thermal decomposition * cyclic voltammetry * kinetics and mechanism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.224, year: 2013

  2. Elaboration of y-fanjasite catalysts containing radioactive elements such as uranyl ion in order to obtain aromatic solvents and heavy amines

    International Nuclear Information System (INIS)

    Nibou, D.

    1990-06-01

    The present work has shown the possibility of ammonia alkylation by n-octanol-l in gaseous phase, in presence of zeolitic catalysts. These catalysts are Y faujasitic types being used in waste water demineralization containing radioactive elements such as uranyl ion. This ion gives to the Y faujasite similar activity and selectivity as those of catalysts containing rare earths or transition metals. Toluene disproportionation has permitted to test beforehand catalysts destined to ammonia alkylation and to compare their mechanism. We have also proved the possibility to produce heavy amines such as tertiary amines which are used as uranium extractant agent. Some zeolites such as ZSM-5, beta, X, A, analcime, HS and Y faujasite type are prepared by hydrothermal synthesis method and characterized by some analysis techniques

  3. Renal hemodynamics in uranyl acetate-induced acute renal failure of rabbits

    International Nuclear Information System (INIS)

    Sudo, M.; Honda, N.; Hishida, A.; Nagase, M.

    1977-01-01

    The role of renal hemodynamic alterations in the curtailment of renal function was studied in rabbits with uranyl acetate-induced acute renal failure. The day following the i.v. injection of uranyl acetate (2 mg/kg of body wt), renal blood flow (RBF) and clearance of creatinine (Ccr) decreased to approximately 60 and 20% of controls, respectively. Intracortical fractional flow distribution, estimated by radioactive microsphere method, did not change. The extraction ratio of para-aminohippurate (EPAH) decreased and the renal extraction of sodium (CNa/Ccr) increased, with minimal structural change in the kidney. Urine output increased two to three times that of the control. After three days oliguria appeared despite complete recovery of RBF. The zonal flow redistributed toward the deep cortex. CCr and EPAH reached their minimums, concomitantly with tubular necrosis and intratubular casts. After seven days animals could be divided into the oliguric and diuretic groups. CCr and EPAH were higher in the diuretic group, while there was no significant difference in RBF and the flow distribution between groups. Regeneration of damaged tubular cells was found in the diuretic group but not in the oliguric group. The findings suggest the minor roles of RBF and the intracortical flow distribution, and a fundamental role of back leakage of filtrate across damaged tubular epithelium in the maintenance of reduced CCR and urine output during the oliguric stage in rabbits with uranyl acetate-induced renal failure

  4. A relativistic density functional study of uranyl hydrolysis and complexation by carboxylic acids in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Rupashree Shyama

    2009-02-10

    In this work, the complexation of uranium in its most stable oxidation state VI in aqueous solution was studied computationally, within the framework of density functional (DF) theory. The thesis is divided into the following parts: Chapter 2 briefly summarizes the relevant general aspects of actinide chemistry and then focuses on actinide environmental chemistry. Experimental results on hydrolysis, actinide complexation by carboxylic acids, and humic substances are presented to establish a background for the subsequent discussion. Chapter 3 describes the computational method used in this work and the relevant features of the parallel quantum chemistry code PARAGAUSS employed. First, the most relevant basics of the applied density functional approach are presented focusing on relativistic effects. Then, the treatment of solvent effects, essential for an adequate modeling of actinide species in aqueous solution, will be introduced. At the end of this chapter, computational parameters and procedures will be summarized. Chapter 4 presents the computational results including a comparison to available experimental data. In the beginning, the mononuclear hydrolysis product of UO{sub 2}{sup 2+}, [UO{sub 2}OH]{sup +}, will be discussed. The second part deals with actinide complexation by carboxylate ligands. First of all the coordination number for uranylacetate will be discussed with respect to implications for the complexation of actinides by humic substances followed by the uranyl complexation of aromatic carboxylic acids in comparison to earlier results for aliphatic ones. In the end, the ternary uranyl-hydroxo-acetate are discussed, as models of uranyl humate complexation at ambient condition.

  5. Enhancement of uranyl fluorescence using trimesic acid: Ligand sensitization and co-fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Maji, S. [Chemistry Group, Materials Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Viswanathan, K.S., E-mail: vish@igcar.gov.in [Chemistry Group, Materials Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2011-09-15

    Trimesic acid (TMA) was shown to sensitize and enhance uranyl fluorescence in aqueous medium, with the enhancement being a maximum at pH 5.0. Fluorescence spectra and lifetime data together suggest that TMA complexes with uranyl (UO{sub 2}{sup 2+}). The fluorescence of UO{sub 2}{sup 2+} in its acid complex is further enhanced by more than two orders of magnitude following the addition of Y{sup 3+}; a process referred to as co-fluorescence, leading to the possibility of detecting uranium at sub ng/mL level. The present study demonstrates, for the first time, fluorescence enhancement of the uranyl species due to co-fluorescence. - Highlights: > Trimesic acid was shown to sensitize and enhance the fluorescence of uranium in aqueous medium. > This ligand also exhibited co-fluorescence of uranium with Y{sup 3+}. > To the best of our knowledge this is the first report of co-fluorescence in uranium. > The enhancement of uranium fluorescence, resulted in detection limits in the ng/mL regime.

  6. A relativistic density functional study of uranyl hydrolysis and complexation by carboxylic acids in aqueous solution

    International Nuclear Information System (INIS)

    Ray, Rupashree Shyama

    2009-01-01

    In this work, the complexation of uranium in its most stable oxidation state VI in aqueous solution was studied computationally, within the framework of density functional (DF) theory. The thesis is divided into the following parts: Chapter 2 briefly summarizes the relevant general aspects of actinide chemistry and then focuses on actinide environmental chemistry. Experimental results on hydrolysis, actinide complexation by carboxylic acids, and humic substances are presented to establish a background for the subsequent discussion. Chapter 3 describes the computational method used in this work and the relevant features of the parallel quantum chemistry code PARAGAUSS employed. First, the most relevant basics of the applied density functional approach are presented focusing on relativistic effects. Then, the treatment of solvent effects, essential for an adequate modeling of actinide species in aqueous solution, will be introduced. At the end of this chapter, computational parameters and procedures will be summarized. Chapter 4 presents the computational results including a comparison to available experimental data. In the beginning, the mononuclear hydrolysis product of UO_2"2"+, [UO_2OH]"+, will be discussed. The second part deals with actinide complexation by carboxylate ligands. First of all the coordination number for uranylacetate will be discussed with respect to implications for the complexation of actinides by humic substances followed by the uranyl complexation of aromatic carboxylic acids in comparison to earlier results for aliphatic ones. In the end, the ternary uranyl-hydroxo-acetate are discussed, as models of uranyl humate complexation at ambient condition.

  7. Mechanistic study of the interaction of uranyl ions with zirconium oxide and zirconium silicate

    International Nuclear Information System (INIS)

    Lomenech, C.

    2002-04-01

    This work deals with structural and thermodynamic studies of the sorption of uranyl species on zircon and zirconia. After determination of the specific areas, of the pH of the isoelectric points, and of the sorption site numbers, thermodynamic data were obtained using alpha spectrometry, for different uranyl concentrations, different background electrolytes (NaClO 4 or KNO 3 ) and different ionic strengths. The structural identification of the surface complexes and sorption sites was carried out using several spectroscopies: XPS spectroscopy allowed a determination of the nature of the sorption sites (≡Zr-O- on zirconia and ≡Si-O- on zircon). Whereas fluorescence decay measurements gave the number of surface species, the combined use of XPS spectroscopy and laser spectro-fluorimetry enabled us to correlate differences in bonding energies and emission wavelengths with differences in the nature of the background electrolyte or in the pH of sorption; DRIFT spectroscopy was a powerful tool for the determination of the presence of sorbed uranyl nitrate species. EXAFS results clearly showed a splitting of the equatorial oxygen atoms in two shells, corresponding to a polydentate, inner-sphere complex. EXAFS results also indicated strong similarities between dry samples and in situ experiments, which confirms the validity of all the spectroscopic measurements. Macroscopic thermodynamic data were then modeled using a surface complexation model (2 pK and constant capacitance models), the results of the structural study being used as constraints for the simulation code FITEQL. (author)

  8. Determination of parameters dissolution of yellow-cake. Production of uranyl nitrate - Gas precipitation of AUC

    International Nuclear Information System (INIS)

    Mellah, A.

    1987-07-01

    The different stages of the purification cycle of yellow-cakes have been studied thoroughly in order to obtain an ammonium uranyl carbonate (AUC) as an intermediate product of uranium dioxide (UO 2 ). The optimal parameters of yellow-cake dissolution, filtration, extraction by solvent, scrubbing and stripping were determined. An original program of thermodynamic calculation was developed for the determination of the free energies of yellow-cake dissolution reactions. Different numerical methods were used to determine the kinetic constant, the reaction order and correlation equations of uranyl nitrate density as a function of U and H + concentrations, before and after the extraction cycle. For the first time, Algerian filteraids were used for the filtration of uranyl nitrate solutions with satisfactory results. A laboratory designed installation enabled the precipitation of AUC by injection of ammonia and carbon dioxide gases. Interesting results have been obtained and further investigations should be carried out in order to optimize all the paremeters of the gas precipitation of AUC

  9. The thermal denigration in fluid-bed to make uranyl product

    International Nuclear Information System (INIS)

    Ma Zhenrong; Cui Yulin; Zhu Changbing; Fan Chuanyong; Liu Yanfeng

    2010-01-01

    Nuclear fuel reprocessing plant used the thermal denigration to high concentration of uranyl nitrate solution in fluid-bed to make uranyl product. First the uranyl nitrate solution were concentrated in evaporator, into 300 gU/L, 600 gU/L, 750 gU/L and 1000 gU/L.When the fluid-bed was in good fluidity state at 320 degree C, the solution was sprayed all over the surface of the fine crystal seeds through the dual-channel air-blast nozzles to make new crystal seed and to make them grow up. The denigration reaction occurred when the internal temperature of the fluid-bed was kept at about 300 degree C by the outside and inside heat apparatus. The product were transported crossing the valve and spiral transfer to pack. The tail gas was purified and discharged. Through the fluid-bed's running, the variation discipline of temperature and the pressure, the effect curve of the quality of product accumulated to pressure drop were determined. At the same time, the gentrification temperature, the distributed heat and the transfer mode were tested. (authors)

  10. Complexes of vanadyl and uranyl ions with the chelating groups of humic matter

    International Nuclear Information System (INIS)

    Goncalves, M.L.S.; Mota, A.M.

    1987-01-01

    The uranyl and vanadyl complexes formed with salicylic, phthalic and 3,4-dihydroxybenzoic acids have been studied by potentiometry in order to determine the stability constants of the Msub(m) Lsub(n) species formed in solution, and the constants for hydrolysis and polymeric complexes, at 25.0 0 , in 0.10, 0.40 and 0.70M sodium perchlorate. MINIQUAD was used in process the data to find the best models for the species in solution, and calculate the formation constants. The uranyl-salicylic acid sytem was also studied by spectrophotometry and the program SQUAD used to process the data obtained. The best models for these systems show that co-ordination of the uranyl ion by carboxylate groups is easier than for the vanadyl ion, whereas the vanadyl ion seems to form more stable complexes with phenolate groups. Both oxo-cations seem to tend to hydrolyse rather than form complexes when the L:M ratios are greater than unity. Although the change in the constants with ionic strength is small, the activity coefficients of the salicylate and phthalate species have been calculated at ionic strengths 0.40 and 0.70M, along with the interaction parameters with Na + , from the stability constants found for the species ML and H 2 L, according to the Bronsted-Guggenheim expression. (author)

  11. Water-Reflected 233U Uranyl Nitrate Solutions in Simple Geometry

    International Nuclear Information System (INIS)

    Elam, K.R.

    2001-01-01

    A number of critical experiments involving 233 U were performed in the Oak Ridge National Laboratory Building 9213 Critical Experiments Facility during the years 1952 and 1953. These experiments, reported in Reference 1, were directed toward determining bounding values for the minimum critical mass, minimum critical volume, and maximum safe pipe size of water-moderated solutions of 233 U. Additional information on the critical experiments was found in the experimental logbooks. Two experiments utilizing uranyl nitrate (UO 2 (NO 3 ) 2 ) solutions in simple geometry are evaluated in this report. Experiment 37 is in a 10.4-inch diameter sphere, and Experiment 39 is in a 10-inch diameter cylinder. The 233 U concentration ranges from 49 to 62 g 233 U/l. Both experiments were reflected by at least 6 inches of water in all directions. Paraffin-reflected uranyl nitrate experiments, also reported in Reference 1, are evaluated elsewhere. Experiments with smaller paraffin reflected 5-, 6-, and 7.5-inch diameter cylinders are evaluated in U233-SOL-THERM-004. Experiments with paraffin reflected 8-, 8.5-, 9-, 10-, and 12-inch diameter cylinders are evaluated in U233-SOL-THERM-002. Later experiments with highly-enriched 235 U uranyl fluoride solution in the same 10.4-inch diameter sphere are reported in HEU-SOL-THERM-010. Both experiments were judged acceptable for use as criticality-safety benchmark experiments

  12. Determination of small amounts of nitric acid in the presence of large amounts of uranium (VI) and extraction of nitric acid into TBP solutions highly loaded with uranyl nitrate

    International Nuclear Information System (INIS)

    Kolarik, Z.; Schuler, R.

    1982-10-01

    A new method for the determination of small amounts of nitric acid in the presence of large amounts of uranium(VI) was elaborated. The method is based on the precipitation of uranium(VI) as iodate and subsequent alkalimetric titration of the acid in the supernatant. The extraction of nitric acid and uranium(VI) with 30% TBP in dodecane was studied at high loading of the organic phase with uranyl nitrate and at 25, 40 and 60 0 C. The results are compared with available published data on the extraction of nitric acid under similar conditions. (orig.) [de

  13. Uranyl nitrate-exposed rat alveolar macrophages cell death: Influence of superoxide anion and TNF α mediators

    International Nuclear Information System (INIS)

    Orona, N.S.; Tasat, D.R.

    2012-01-01

    Uranium compounds are widely used in the nuclear fuel cycle, military and many other diverse industrial processes. Health risks associated with uranium exposure include nephrotoxicity, cancer, respiratory, and immune disorders. Macrophages present in body tissues are the main cell type involved in the internalization of uranium particles. To better understand the pathological effects associated with depleted uranium (DU) inhalation, we examined the metabolic activity, phagocytosis, genotoxicity and inflammation on DU-exposed rat alveolar macrophages (12.5–200 μM). Stability and dissolution of DU could differ depending on the dissolvent and in turn alter its biological action. We dissolved DU in sodium bicarbonate (NaHCO 3 100 mM) and in what we consider a more physiological vehicle resembling human internal media: sodium chloride (NaCl 0.9%). We demonstrate that uranyl nitrate in NaCl solubilizes, enters the cell, and elicits its cytotoxic effect similarly to when it is diluted in NaHCO 3 . We show that irrespective of the dissolvent employed, uranyl nitrate impairs cell metabolism, and at low doses induces both phagocytosis and generation of superoxide anion (O 2 − ). At high doses it provokes the secretion of TNFα and through all the range of doses tested, apoptosis. We herein suggest that at DU low doses O 2 − may act as the principal mediator of DNA damage while at higher doses the signaling pathway mediated by O 2 − may be blocked, prevailing damage to DNA by the TNFα route. The study of macrophage functions after uranyl nitrate treatment could provide insights into the pathophysiology of uranium‐related diseases. -- Highlights: ► Uranyl nitrate effect on cultured macrophages is linked to the doses and independent of its solubility. ► At low doses uranyl nitrate induces generation of superoxide anion. ► At high doses uranyl nitrate provokes secretion of TNFα. ► Uranyl nitrate induces apoptosis through all the range of doses tested.

  14. Hydrothermal synthesis of uranyl squarates and squarate-oxalates: hydrolysis trends and in situ oxalate formation.

    Science.gov (United States)

    Rowland, Clare E; Cahill, Christopher L

    2010-07-19

    We report the synthesis of two uranyl squarates and two mixed-ligand uranyl squarate-oxalates from aqueous solutions under hydrothermal conditions. These products exhibit a range of uranyl building units from squarates with monomers in (UO(2))(2)(C(4)O(4))(5).6NH(4).4H(2)O (1; a = 16.731(17) A, b = 7.280(8) A, c = 15.872(16) A, beta = 113.294(16) degrees , monoclinic, P2(1)/c) and chains in (UO(2))(2)(OH)(2)(H(2)O)(2)(C(4)O(4)) (2; a = 12.909(5) A, b = 8.400(3) A, c = 10.322(4) A, beta = 100.056(7) degrees , monoclinic, C2/c) to two squarate-oxalate polymorphs with dimers in (UO(2))(2)(OH)(C(4)O(4))(C(2)O(4)).NH(4).H(2)O (3; a = 9.0601(7) A, b = 15.7299(12) A, c = 10.5108(8) A, beta = 106.394(1) degrees , monoclinic, P2(1)/n; and 4; a = 8.4469(6) A, b = 7.7589(5) A, c = 10.5257(7) A, beta = 105.696(1) degrees , monoclinic, P2(1)/m). The dominance at low pH of monomeric species and the increasing occurrence of oligomeric species with increasing pH suggests that uranyl hydrolysis, mUO(2)(2+) + nH(2)O right harpoon over left harpoon [(UO(2))(m)(OH)(n)](2m-n) + nH(+), has a significant role in the identity of the inorganic building unit. Additional factors that influence product assembly include in situ hydrolysis of squaric acid to oxalic acid, dynamic metal to ligand concentration, and additional binding modes resulting from the introduction of oxalate anions. These points and the effects of uranyl hydrolysis with changing pH are discussed in the context of the compounds presented herein.

  15. Characterization of combustion synthesized zirconia powder by UV

    Indian Academy of Sciences (India)

    . The surface acidbase properties of these samples were also investigated by indicator titration method. The catalytic activity was probed with transfer hydrogenation reaction in liquid phase. It was found that combustion synthesized zirconia did ...

  16. Sol–gel synthesized mesoporous anatase titanium dioxide ...

    Indian Academy of Sciences (India)

    for dye sensitized solar cell (DSSC) applications. R GOVINDARAJ1,∗, M ... DSSC than rutile phase. In this work, we have synthesized hierarchically structured ... Hydrolysis and polycondensation reaction mechanism of sol–gel process. 2.

  17. Preparative conditions and vibrational study of HUP : phase transition and conductivity mechanisms

    International Nuclear Information System (INIS)

    Thi, M.P.; Novak, A.; Colomban, Ph.

    1985-01-01

    Among solid protonic conductors HUP (H 3 OUO 2 PO 4 .3 H 2 O) exhibits very high conducting properties. Uranyl/phosphate hydrates belonging to the HUP family (HUP ; UO 2 (H 2 PO 4 ) 2 .3 H 2 O ; (U= 2 ) 3 (PO 4 ) 2 .4 H 2 O ; (UO O 2 )sub(1.43)PO 4 Hsub(0.14) 2-3.5 H 2 O) have been synthesized in different forms (crystals, powders, films, ...) and characterized by various methods: chemical analysis, DTA, TGA, SEM, X-Ray diffraction, IR and Raman spectroscopy. Morphological studies reveal the presence of various particulat es, from ultrafine powders ( 2 O washing of HUP. Infrared and Raman spectra of polycrystalline H 3 OUO 2 PO 4 .3 H 2 O (HUP) have been investigated at various temperatures between 50 K and 300 K. The most temperature-sensitive bands correspond to PO 4 and H 2 O librations; U-OPO 3 stretching and OH stretching vibrations indicate four different phases of HUP and allow to propose a phasetransition mechanism from a bidimensionnal, quasi-liquid state of a protonated species in the room-temperature phase to a fully ordered crystal below 130 K. The protonic conductivity mechanism of room- and low-temperature phases is discussed. (author)

  18. Spurious in PLL-DDS frequency synthesizers

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Věnceslav František; Štursa, Jarmil

    2002-01-01

    Roč. 2, č. 1 (2002), s. 48-51 ISSN 1335-8243. [Digital Signal Processing and Multimedia Communications DSP-MCOM 2001 /5./. Košice, 27.11.2001-29.11.2001] R&D Projects: GA ČR GA102/00/0958 Institutional research plan: CEZ:AV0Z2067918 Keywords : frequency synthesizers * phase locked loops * direct digital synthesis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  19. Electrochemical studies on the reduction of uranyl ions in nitric acid-hydrazine media at platinum electrode

    International Nuclear Information System (INIS)

    Mishra, Satyabrata; Sini, K.; Mallika, C.; Kamachi Mudali, U.; Jagadeeswara Rao, Ch.

    2015-01-01

    Production of uranous nitrate with good conversion efficiency is one of the major steps in the aqueous reprocessing of spent fuels of nuclear reactors, as U(IV) is used for the separation of Pu from U by the selective reduction of Pu(IV) into practically non-extractable Pu(III) in aqueous streams. Electro-reduction of uranyl ions has the advantage of not introducing corrosive chemicals into the process stream. High current efficiency with maximum conversion of U(VI) to U(IV) can be achieved in continuous as well as batch mode electro-reduction, if the process is voltage-controlled rather than current controlled. As potentiostatic studies reveal the mechanism of reduction of uranyl ions in potential controlled electrolysis, the reduction behavior of uranyl ions (UO 2 2+ ) in nitric acid and nitric acid-hydrazine media were investigated by Cyclic Voltammetric (CV) and Chronopotentiometric (CP) techniques using platinum working electrode at 298 K. Heterogeneous electron transfer rate constant (ks) for uranyl reduction was estimated at a very low concentration of nitric acid (0.05 M) using Klinger and Kochi equation. Values of the diffusion coefficients were determined as a function of acidity with and without hydrazine. Reduction of uranyl ions was found to be under kinetic as well as diffusion control when the concentration of nitric acid was 0.05 M and in the absence of hydrazine. However, as the acidity of the supporting electrolyte increased, the reduction was purely under kinetic control. (author)

  20. Uranyl sensor based on a N,N?-bis(salicylidene)-2-hydroxy-phenylmethanediamine and multiwall carbon nanotube electrode

    International Nuclear Information System (INIS)

    Sayed Mehdi Ghoreishi; Mohsen Behpour; Samaneh Mazaheri; Hossein Naeimi

    2012-01-01

    The electrochemical determination of uranyl was investigated by using carbon paste electrode modified with a Schiff base namely N,N'-bis(salicylidene)-2-hydroxy-phenylmethanediamine (SHPMD/CPE) and also in the presence of carbon nanotube (SHPMD/CNT/CPE). The both modified electrodes displayed an irreversible peak at E pa = 0.798 V versus Ag/AgCl. The electrocatalytic reduction of uranyl has been studied on SHPMD/CNT/CPE, using cyclic and differential pulse voltammetry, chronocoulometry and linear sweep techniques. Electrochemical parameters including the diffusion coefficient (D), the electron transfer coefficient (α), the ionic exchange current (i) and the redox reaction rate constant (K) were determined for the reduction of uranyl on the surface of the modified electrodes. Linear range concentration is 0.002-0.6 μmol L -1 and the detection limit of uranyl is 0.206 nmol L -1 . The proposed method was used to detect uranyl in natural waters and good recovery was achieved. (author)

  1. Thermal decomposition of uranyl nitrate hexahydrate. Study of intermediate reaction products; Decomposition thermique du nitrate d'uranyle hexahydrate etude des intermediaires de cette decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Chottard, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1970-07-01

    The thermal decomposition of uranyl nitrate hexahydrate has been carried but at constant pressure and constant rate of reaction. The following intermediary products have been shown to exist and isolated: UO{sub 2}(NO{sub 3}){sub 2}.3H{sub 2}O; UO{sub 2}(NO{sub 3}){sub 2}. 2H{sub 2}O; UO{sub 2}(NO{sub 3}){sub 2}. H{sub 2}O; UO{sub 2}(NO{sub 3}){sub 2} and UO{sub 3}. These products, together with the hexahydrate UO{sub 2} (NO{sub 3}){sub 2}.6H{sub 2}O, have been studied by: - X-ray diffraction, using the Debye-Scherrer method.- infra-red spectrography: determination of the type of bonding for the water and the nitrate groups. - nuclear magnetic resonance: study of the mobility of water molecules. The main results concern: - the water molecule bonds in the series of hydrates with 6.3 and 2 H{sub 2}O. - isolation and characterization of uranyl nitrate monohydrate, together with the determination of its molecular structure. - the mobility of the water molecules in the series of the hydrates with 6.3 and 2 H{sub 2}O. An analysis is made of the complementary results given by infra-red spectroscopy and nuclear magnetic resonance; they are interpreted for the whole of the hydrate series. [French] La decomposition thermique du nitrate d'uranyle hexahydrate a ete effectuee en operant a pression et vitesse de decomposition constantes. Les produits intermediaires suivants ont ete mis en evidence et isoles: UO{sub 2}(NO{sub 3}){sub 2}, 3H{sub 2}O; UO{sub 2}(NO{sub 3}){sub 2}, 2H{sub 2}O; UO{sub 2}(NO{sub 3}){sub 2},H{sub 2}O; UO{sub 2}(NO{sub 3}){sub 2} et UO{sub 3}. Ces composes, ainsi que l'hexahydrate UO{sub 2}(NO{sub 3} ){sub 2}, 6H{sub 2}O ont ete etudies par: - diffraction des rayons X, selon la methode Debye-Scherrer.- spectrographie infra-rouge: determination des modes de liaison de l'eau et des groupements nitrate. - resonance magnetique nucleaire: etude de la mobilite des molecules d'eau. Les principaux resultats portent sur: - les liaisons des molecules d'eau dans la

  2. Derivation of an empirical formula for determining water content of mixed uranyl nitrate-thorium nitrate solutions

    International Nuclear Information System (INIS)

    Min, Duck Kee; Choi, Byung Il; Ro, Seung Gy; Eom, Tae Yoon; Kim, Zong Goo

    1986-01-01

    Densities of a large number of mixed uranyl nitrate-thorium nitrate solutions were measured with pycnometer. By the least squares analysis of the experimental result, an empirical formula for determining water content of mixed uranyl nitrate-thorium nitrate solutions as functions of uranium concentration, thorium concentration and nitric acid normality is derived; W=1.0-0.3580 C u -0.4538 C Th -0.0307H + where W, C u , C Th , and H + stand for water content(g/cc), uranium concentration (g/cc), thorium concentration(g/cc), and nitric acid normality, respectively. Water contents of the mixed uranyl nitrate-thorium nitrate solutions are calculated by using the empirical formular, and compared with the values calculated by Bouly's equation in which an additional data, solution density, is required. The two results show good agreements within 2.7%. (Author)

  3. Application of membrane LaF3 electrode in the determination of stability constants of Uranyl Fluoride complex in solution

    International Nuclear Information System (INIS)

    Muzakky; Iswani GS; Mintolo

    1996-01-01

    A membrane electrode LaF 3 has been applied in the determination of uranyl fluoride complex stability constant in solution. The determination is based on the detection of free F ion in solution as a result of hydrolysis reaction (process) of uranyl ions into the uranyl hydroxide form at low pH. The experiment results showed that there was no effect of ammonium carbonate 2 M titran, flow rate on the electrode response. The F release is optimum at pH 1. The free F ion in solution is calculated from the standard curve at pH 1, after the fluoride concentration at the same pH has been corrected. Using the plot of average number of ligand binding (n) versus minus log of free ligand (-log F) the value of β1 = 4.4, β2 = 7.48, β3=9.73, and β4 = 11.67

  4. Effect of uranyl nitrate and free acid concentration in feed solution of gelation on UO2 kernel quality

    International Nuclear Information System (INIS)

    Masduki, B.; Wardaya; Widarmoko, A.

    1996-01-01

    An investigation on the effect of uranium and free nitric acid concentration of uranyl nitrate as feed of gelation process on quality of UO 2 kernel was done.The investigation is to look for some concentration of uranyl nitrate solutions those are optimum as feed for preparation of gelled UO 3 . Uranyl nitrate solution of various concentration of uranium (450; 500; 550; 600; 650; 700 g/l) and free nitric acid of (0.9; 1.0; 1.1 N) was made into feed solutions by adding urea and HMTA with mole ratio of urea/uranium and HMTA/uranium 2.1 and 2.0. The feed solutions were changed into spherical gelled UO 3 by dropping was done to get the optimum concentrations of uranyl nitrate solutions. The gelled UO 3 was soaked and washed with 2.5% ammonia solution for 17 hours, dried at 70 o C, calcined at 350 o C for 3 hours then reduced at 850 o C for 3 hours. At every step of the steps process the colour and percentage of well product of gelled UO 3 were noticed. The density and O/U ratio of end product (UO 2 kernel) was determined, the percentage of well product of all steps process was also determined. The three factor were used to chose the optimum concentration of uranyl nitrate solution. From this investigation it was concluded that the optimum concentration of uranyl nitrate was 600 g/l uranium with free nitric acid 0,9 - 1,0 N, the percentage of well product was 97% density of 6.12 - 4.8 g/cc and O/U ratio of 2.15 - 2.06. (author)

  5. DFT study of uranyl peroxo complexes with H2O, F-, OH-, CO3(2-), and NO3(-).

    Science.gov (United States)

    Odoh, Samuel O; Schreckenbach, Georg

    2013-05-06

    The structural and electronic properties of monoperoxo and diperoxo uranyl complexes with aquo, fluoride, hydroxo, carbonate, and nitrate ligands have been studied using scalar relativistic density functional theory (DFT). Only the complexes in which the peroxo ligands are coordinated to the uranyl moiety in a bidentate mode were considered. The calculated binding energies confirm that the affinity of the peroxo ligand for the uranyl group far exceeds that of the F(-), OH(-), CO3(2-), NO3(-), and H2O ligands. The formation of the monoperoxo complexes from UO2(H2O)5(2+) and HO2(-) were found to be exothermic in solution. In contrast, the formation of the monouranyl-diperoxo, UO2(O2)2X2(4-) or UO2(O2)2X(4-/3-) (where X is any of F(-), OH(-), CO3(2-), or NO3(-)), complexes were all found to be endothermic in aqueous solution. This suggests that the monoperoxo species are the terminal monouranyl peroxo complexes in solution, in agreement with recent experimental work. Overall, we find that the properties of the uranyl-peroxo complexes conform to well-known trends: the coordination of the peroxo ligand weakens the U-O(yl) bonds, stabilizes the σ(d) orbitals and causes a mixing between the uranyl π- and peroxo σ- and π-orbitals. The weakening of the U-O(yl) bonds upon peroxide coordination results in uranyl stretching vibrational frequencies that are much lower than those obtained after the coordination of carbonato or hydroxo ligands.

  6. Extraction study on uranyl nitrate for energy applications

    Science.gov (United States)

    Giri, R.; Nath, G.

    2017-07-01

    Due to the ever-growing demand of energy nuclear reactor materials and the nuclear energy are now considered to be the most critical materials and source of energy for future era. Deposition of nuclear wastes in different industry, nuclear power sector are very much toxic in open environment which are hazardous to living being. There are different methods for extraction and reprocessing of these materials which are cost effective and tedious process. Ultrasonic assisted solvent extraction process is a most efficient and economical way for extraction of such type materials. The presence of third phase in mixing of extractants-diluent pair with aqueous phase imposes the problems in extraction of nuclear reactor materials. The appropriate solvent mixture in proper concentration is an important step in the solvent extraction process. Study of thermo-physical properties helps in selecting an optimum blend for extraction process. In the present work, the extraction of uranium with the binary mixture of Methyl Ethyl Ketone (MEK) and Kerosene was investigated and discussed with the variation of ultrasonic frequency for different temperatures. The result shows that the low frequency and low temperature is suitable environment for extraction. The extraction of uranium by this method is found to be a better result for extraction study in laboratory scale as well as industrial sector.

  7. The research of technology and equipment for a microwave denitration process of the uranyl nitrate solution

    International Nuclear Information System (INIS)

    Bao Weimin; Wang Xuejun; Ma Xuquan; Shi Miaoyi; Zhang Zhicheng; Bao Zhu Tian.

    1991-01-01

    In order to improve the present process of converting the plutonium nitrate into oxide powder in the nuclear fuel cycle, a new conversion process for the direct denitration using microwave heating has been developed. Microwave denitration is based on intramolecular polarization of a material in electric field and has no need of a process of heat transfer during microwave heating, so that the whole material can be heated quickly and uniformly. The thermal decomposition reactions of Pu, U, Th and RE nitrate have been analyzed and compared. The uranyl nitrate solution was chosen as imitative plutonium nitrate solution. The performance parameters ε r tanδ of U, Th and RE nitrate and oxide in microwave field were measured. The data obtained show that all of them could absorb microwave energy well and cause heating decomposition reactions. The microwave denitration test unit was designed and made. Denitration tests for rare-earths nitrate and uranyl nitrate solutions were performed. It could be completed in one step that the uranyl nitrate solution was evaporated, dryed and denitrated in a vessel. The denitrated products are a porous lump and easy to scrape off from the denitration vessel. The main forms of the products UO 3 ·0.8H 2 O and U 3 O 8 which have excellent powder properties. The capacity of the denitration unit is 1.3 kg UO 3 /h. According to the experimental results the simplicity, feasibility and good repeatability of the process have been fully proved. The unit operates easily and is adaptable to conversion of nitrate in nuclear fuel cycle. (author)

  8. Computer simulation of uranyl uptake by the rough lipopolysaccharide membrane of Pseudomonas aeruginosa.

    Science.gov (United States)

    Lins, Roberto D; Vorpagel, Erich R; Guglielmi, Matteo; Straatsma, T P

    2008-01-01

    Heavy metal environmental contaminants cannot be destroyed but require containment, preferably in concentrated form, in a solid or immobile form for recycling or final disposal. Microorganisms are able to take up and deposit high levels of contaminant metals, including radioactive metals such as uranium and plutonium, into their cell wall. Consequently, these microbial systems are of great interest as the basis for potential environmental bioremediation technologies. The outer membranes of Gram-negative microbes are highly nonsymmetric and exhibit a significant electrostatic potential gradient across the membrane. This gradient has a significant effect on the uptake and transport of charged and dipolar compounds. However, the effectiveness of microbial systems for environmental remediation will depend strongly on specific properties that determine the uptake of targeted contaminants by a particular cell wall. To aid in the design of microbial remediation technologies, knowledge of the factors that determine the affinity of a particular bacterial outer membrane for the most common ionic species found in contaminated soils and groundwater is of great importance. Using our previously developed model for the lipopolysaccharide (LPS) membrane of Pseudomonas aeruginosa, this work presents the potentials of mean force as the estimate of the free energy profile for uptake of sodium, calcium, chloride, uranyl ions, and a water molecule by the bacterial LPS membrane. A compatible classical parameter set for uranyl has been developed and validated. Results show that the uptake of uranyl is energetically a favorable process relative to the other ions studied. At neutral pH, this nuclide is shown to be retained on the surface of the LPS membrane through chelation with the carboxyl and hydroxyl groups located in the outer core.

  9. Structural variability in uranyl-lanthanide hetero-metallic complexes with DOTA and oxalato ligands

    International Nuclear Information System (INIS)

    Thuery, P.

    2009-01-01

    Four novel 4f-5f hetero-metallic complexes could be obtained from the reaction of uranyl and lanthanide nitrates with DOTA (H 4 L) under hydrothermal conditions. In all cases, as in the previous examples reported, additional oxalato ligands are formed in situ. Variations in the stoichiometry of the final products and the presence of hydroxo ions in some cases appear to result in a large structural variability. In the two isomorphous complexes [(UO 2 ) 2 Ln 2 (L) 2 (C 2 O 4 )] with Ln = Sm(1) or Eu(2), the lanthanide ion is located in the N 4 O 4 site and is also bound to a carboxylate oxygen atom from a neighbouring unit, to give zigzag chains which are further linked to one another by [(UO 2 ) 2 (C 2 O 4 )] 2+ di-cations, resulting in the formation of a 3D framework. In [(UO 2 ) 4 Gd 2 (L) 2 (C 2 O 4 ) 3 (H 2 O) 6 ].2H 2 O (3), 2D bilayer subunits of the 'double floor' type with uranyl oxalate pillars are assembled into a 3D framework by other, disordered uranyl ions. [(UO 2 ) 2 Gd(L)(C 2 O 4 )(OH)].H 2 O (4) is a 2D assembly in which cationic {[(UO 2 ) 2 (C 2 O 4 )(OH)] + } n chains are linked to one another by the [Gd(L)] - groups. The most notable feature of this compound is the environment of the 4f ion, which is eight-coordinate and twisted square anti-prismatic (TSA'), instead of nine-coordinate mono-capped square anti-prismatic (SA), as generally observed in DOTA complexes of gadolinium(III) and similarly-sized ions. (author)

  10. Effect of temperature on the mechanisms of interaction between uranyl ion and zirconium oxo-phosphate

    International Nuclear Information System (INIS)

    Almazan Torres, Maria Guadalupe

    2007-01-01

    Uranium sorption onto Zr 2 O(PO 4 ) 2 has been studied between 298 K and 363 K, in 0.1 M NaClO 4 medium. Potentiometric titrations were realized to determine temperature dependency of the acid-base properties (pH pcn , acidity constants). Classical batch experiments were performed at different temperatures. The sorption experiments revealed that the uranium sorption onto Zr 2 O(PO 4 ) 2 is favoured with the temperature. Structural characterization of the surface complexes was performed by both Time-Resolved Laser-Induced Fluorescence (TRLIF) and EXAFS spectroscopy. The TRLIF measurements vs. temperature revealed two uranyl surface complexes. No influence of the temperature onto the nature surface complex was observed. The EXAFS analysis showed a splitting of the equatorial oxygen atoms in two shells, corresponding to uranyl bidentate, inner-sphere complexes. The obtained structural uranyl surface complex information was used to simulate (using a constant capacitance model) the sorption edges. The proposed complexes equilibrium model consists of the following surface complexes: (≡ZrOH) 2 UO 2 2+ and (≡PO) 2 UO 2 . Besides the stability constants for the surface complexes, the thermodynamic parameters ΔH 0 and ΔS 0 were determined using the van't Hoff equation. The enthalpy values associated to the U(VI) retention onto Zr 2 O(PO 4 ) 2 , determined by the temperature dependence of the stability constants, testify that the formation of the complex (≡PO) 2 UO 2 (55 kJ/mol) is endothermic, while no influence of the temperature was observed for the formation of the complex (≡ZrOH) 2 UO 2 2+ . The adsorption reaction of the last complex is then driven by entropy. In addition, calorimetric measurements of uranium sorption onto Zr 2 O(PO 4 ) 2 were carried out to directly quantify the enthalpy associated to the retention processes. (author)

  11. Behind adhesion of uranyl onto montmorillonite surface: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.; Zaoui, A., E-mail: azaoui@polytech-lille.fr

    2013-10-15

    Highlights: • We investigated the adsorption of uranyl onto Montmorillonite surface. • We studied the surface energy between layered Montmorillonite sheets. • We studied the work of adhesion between radionuclide and charged Montmorillonite. -- Abstract: We have performed molecular dynamics simulations to investigate the adsorption of radionuclide elements species onto substituted Montmorillonite (001) surface in the presence of different counterions. The structure and the dynamics of uranyl ion as well as its aquo, chloride ion, and carbonate complexes are analyzed. In addition, we have studied the surface energy between layered Montmorillonite sheets and the work of adhesion between radionuclide and charged Montmorillonite. The clay model used here is a Wyoming-type Montmorillonite with 0.75e negative charge per unit cell resulting from substitutions in Octahedral and Tetrahedral sheets. The system model was constructed based on CLAYFF force field potential model. To evaluate the thermodynamic work of adhesion, each surface and clay layer regions are converted to a thin film model. One and two species of radionuclide elements (UO{sub 2}(H{sub 2}O){sub 5},UO{sub 2}CO{sub 3}(H{sub 2}O){sub 5}, and UO{sub 2}Cl{sub 2}(H{sub 2}O){sub 5}) were deposited near the clay surface in a pseudo-two-dimensional periodic cell. Analysis shows that the uranyl ion structure is preserved with two axial oxygen atoms detected at 1.8 Å. Radial distribution functions results indicate that average U-O{sub w} distances are 2.45–2.61 Å, and 2.29–2.40 Å for U-O{sub c} distance. Average U-Cl distances are 2.78–3.08 Å, which is relatively larger than that of Uranium atom-Oxygen atom because of electrostatic factors.

  12. Spectropolarimetric analysis. Communication 14. Determination of uranyl with d-tartaric acid

    Energy Technology Data Exchange (ETDEWEB)

    Bakalov, V D; Dunina, V V; Potapov, V M [Moskovskij Gosudarstvennyj Univ. (USSR)

    1982-02-01

    The possibility has been shown of improving the sensitivity and precision of determination of uranium (6) in the form of its tartrate complex by using spectropolarimetry instead of polarimetry and circular dichroism instead of optical rotatory dispersion. The method makes it possible to reduce reagent consumption, to expand a range of uranium(6) concentration, which could be determined, due to changes of the cell length and reading range. On the basis of the circular dichroism spectrum of the uranyl-tartrate complex, its symmetry has been estimated to be Dsub(4h) with the coordination number of four on the equatorial plane.

  13. Skin contamination resulting from an uranyl nitrate burn. An incident study

    International Nuclear Information System (INIS)

    Quesne, B.; Auriol, B.; Berard, P.; Chalabreysse, J.

    1993-01-01

    The authors describe the circumstances of a burn incident on hand by a mixture of diluted nitric acid and uranyl nitrate. The burn is located on the left hand fingers. After important washings uranium remains on the fingers. During about ten days, the worker is examined and the therapy is going on till the total radioactivity disappearance. Urine collection of twenty four hours is prescribed during the treatment. The whole activity is kept on the burnt skin. The quick desquamation is the elimination way of the skin retention. 6 refs., 3 figs., 4 tabs

  14. Development of a reduction process of ammonium uranyl carbonate to uranium dioxide in a fluidized bed

    International Nuclear Information System (INIS)

    Gomes, R.P.; Riella, H.G.

    1990-07-01

    Laboratory development of ammonium uranyl carbonate (AUC) reduction to uranium dioxide (UO 2 ) using fluidized bed furnace technique is described. The reaction is carried out at 500-550 0 C using hydrogen, liberated from cracking of ammonia, as a reducing agent. As the AUC used is obtained from uranium hexafluoride (UF 6 ) it contains considerable amount of fluoride (approx. 500μg/g) as contaminant. The presence of fluoride leads to high corrosion rates and hence the fluoride concentration is reduced by pyrohydrolisis of UO 2 . Physical and Chemical properties of the final product (UO 2 ) obtained were characterized. (author) [pt

  15. U3O8 powder from uranyl-loaded cation exchange resin

    International Nuclear Information System (INIS)

    Mosley, W.C.

    1985-01-01

    Large batches of U 3 O 8 , suitable for powder metallurgy fabrication of Al-U 3 O 8 cores for reactor fuel tubes, have been produced by deep-bed calcination of granular uranyl-loaded macroporous sulfonate cation exchange resin at 900 to 950 0 C in air. Deep-bed calcination is the backup process for the reference process of rotary calcination and sintering. These processes are to be used for recycling uranium, and to produce U 3 O 8 in the Fuel Production Facility to be built at the Savannah River Plant. 2 refs., 6 figs

  16. Interfacial Interaction of Titania Nanoparticles and Ligated Uranyl Species: A Relativistic DFT Investigation.

    Science.gov (United States)

    Zhao, Hong-Bo; Zheng, Ming; Schreckenbach, Georg; Pan, Qing-Jiang

    2017-03-06

    To understand interfacial behavior of actinides adsorbed onto mineral surfaces and unravel their structure-property relationship, the structures, electronic properties, and energetics of various ligated uranyl species adsorbed onto TiO 2 surface nanoparticle clusters (SNCs) were examined using relativistic density functional theory. Rutile (110) and anatase (101) titania surfaces, experimentally known to be stable, were fully optimized. For the former, models studied include clean and water-free Ti 27 O 64 H 20 (dry), partially hydrated (Ti 27 O 64 H 20 )(H 2 O) 8 (sol) and proton-saturated [(Ti 27 O 64 H 20 )(H 2 O) 8 (H) 2 ] 2+ (sat), while defect-free and defected anatase SNCs involving more than 38 TiO 2 units were considered. The aquouranyl sorption onto rutile SNCs is energetically preferred, with interaction energies of -8.54, -10.36, and -2.39 eV, respectively. Energy decomposition demonstrates that the sorption is dominated by orbital attractive interactions and modified by steric effects. Greater hydrogen-bonding involvement leads to increased orbital interactions (i.e., more negative energy) from dry to sol/sat complexes, while much larger steric interaction in the sat complex significantly reduces the sorption interaction (i.e., more positive energy). For dry SNC, adsorbates were varied from aquo to aquo-carbonato, to carbonato, to hydroxo uranyl species. Longer U-O surf /U-Ti distances and more positive sorption energies were calculated upon introducing carbonato and hydroxo ligands, indicative of weaker uranyl sorption onto the substrate. This is consistent with experimental observations that the uranyl sorption rate decreases upon raising solution pH value or adding carbon dioxide. Anatase SNCs adsorbing aquouranyl are even more exothermic, because more bonds are formed than in the case of rutile. Moreover, the anatase sorption can be tuned by surface defects as well as its Ti and O stoichiometry. All the aquouranyl-SNC complexes show similar

  17. Development of fluidized-bed furnace for thermal treatment of ammonium uranyl carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, U C; Anuradha, M; Meena, R [Nuclear Fuel Complex, Hyderabad (India)

    1994-06-01

    At present the ammonium uranyl carbonate (AUC) route is developed at a scale of 10 kg/day of UO{sub 2}. This UO{sub 2} is directly compactible and sinterable to densities of 10.55-10.65 gm/cc. The equipment developed include precipitation tank with filtration and methanol washing and fluidized bed furnaces for thermal treatment of AUC and U{sub 3}O{sub 8}. During the design and development of these furnaces many experiments were conducted to study fluidization of AUC powder. In this paper the findings of these studies are presented. (author). 3 refs., 4 figs., 3 tabs.

  18. Benchmark calculation for water reflected STACY cores containing low enriched uranyl nitrate solution

    International Nuclear Information System (INIS)

    Miyoshi, Yoshinori; Yamamoto, Toshihiro; Nakamura, Takemi

    2001-01-01

    In order to validate the availability of criticality calculation codes and related nuclear data library, a series of fundamental benchmark experiments on low enriched uranyl nitrate solution have been performed with a Static Experiment Criticality Facility, STACY in JAERI. The basic core composed of a single tank with water reflector was used for accumulating the systematic data with well-known experimental uncertainties. This paper presents the outline of the core configurations of STACY, the standard calculation model, and calculation results with a Monte Carlo code and JENDL 3.2 nuclear data library. (author)

  19. Recovery of uranium from uranyl nitrate raffinate. Contributed Paper PE-06

    International Nuclear Information System (INIS)

    Anilkumar Reddy, A.M.; Shiva Kumar, M.; Varadan, K.M.K.; Babaji, P.; Sairam, S. Sheela; Saibaba, N.

    2014-01-01

    At New Uranium Oxide Fuel Plant, NUOFP(O) of Nuclear Fuel Complex (NFC), the Uranyl Nitrate Raffinate (UNR) generated during solvent extraction process is washed with Treated Lean Solvent(TLS) to recover residual U. Earlier this UNR consisting of 0.5-1 gm/l and 2.5 FA was neutralised with vapour ammonia. The slurry was then filtered over pre coat drum filter and the resultant Uranyl Nitrate Raffinate cake (UNRC) was stored in polyethylene lined MS drums. The valuable U was thus being locked up in UNRC. Also, the storage of UNRC drums required lot of floor space which have to be repacked frequently to contain the radioactivity. Hence the need has come to avoid the generation of UNRC and the recovery of U from the already generated UNRC. The generation of UNRC was avoided by developing alternate process of UNR treatment with Treated Lean Solvent for the removal of residual U and the resulting Acidic Raffinate Slurry (ARS) is disposed. The Uranium recovery from UNRC is done by dissolving the cake in Uranyl Nitrate Raffinate solution to leach the hexavalent Uranium by utilizing the free acidity in UNR. The leaching time is about six hours and the uranium forms uranyl nitrate. The resulting leach solutions are relatively dilute but complex acidic nitrate solutions containing wide variety of ions. Metallic ions commonly present include uranium, iron, magnesium, aluminium, sodium, calcium etc. The uranium concentration is normally 1-1.5 g/L. This uranium is separated by solvent extraction. The active agent in solvent extraction is Tri Butyl Phosphate in kerosene that can selectively extract uranium into an organic complex which is insoluble in aqueous. The organic used for extraction is Treated Lean Solvent in the quality of freshly prepared solvent and the resulting Acidic Raffinate Slurry is disposed by sale. The leaching of Uranium from UNRC was done in plant scale and about 1200 kgs of UNRC was successfully processed in trial batch. The paper deals with details of

  20. Investigations on uranyl nitrate solubility in nitric acid in different concentrations at temperatures of 50C

    International Nuclear Information System (INIS)

    Deigele, E.

    1983-01-01

    The solubility of uranyl nitrate was studied in nitric acid solutions of different concentrations at a temperature of 5 0 C. This temperature was chosen with a view to using water as coolant and to facilitate the handling of the strong acid solutions. Accurate curves were established by a multitude of accurate measurements in the high concentration range. Further solubility curves can be derived from this basic curve. Some of the precipitates in the interesting regions of the solubility curve were analyzed. (orig./EF) [de