Showing papers on "Uranyl published in 1987"
134 citations
Journal Article•
TL;DR: The related crystal structures of three uranyl oxide hydrate minerals, becquerelite, billietite, and protasite, have been determined by single-crystal X-ray diffraction as mentioned in this paper.
Abstract: The related crystal structures of three uranyl oxide hydrate minerals, becquerelite, billietite, and protasite, have been determined by single-crystalX-ray diffraction. The chemical formulae have been determined by electron-microprobe analyses. Becquerelite, Ca[(U02)604(OH)6].8H20,is orthorhombic, Pn21a,a = 13.8378(8), b = 12.3781(12),c = 14.9238(9) A, Z = 4, R(Fobs)= 0.083 (2853 reflections). Billietite, Ba[(U02)604(OH)6]. 4H20, is orthorhombic, Pbn21,a = 12.0720(22), b = 30.167(4), c = 7.1455(5) A, Z = 4, R(Fobs) = 0.139 (4104 reflections). Protasite, Ba[(U02)30l0H)2]. 3H20, is monoclinic, Pn, a = 12.2949(16),b = 7.2206(10), c = 6.9558(8) A, (j = 90.401(15)°,Z = 2, R(Fobs) = 0.073 (2505 reflections). Each uranyl ion is coordinated to five other oxygen atoms in a plane nearly perpendicular to the uranyl axis forming infinite sheets that resemble those of aU308 in projection. The sheets are bonded together by large interlayer cations and water molecules.
82 citations
TL;DR: In this article, a porous, amidoxime-group-containing membrane was prepared by radiation-induced graft polymerization of acrylonitrile onto porous polyethylene film followed by chemical conversion of the produced cyano group to an amidoxide group.
Abstract: A porous, amidoxime-group-containing membrane was prepared by radiation-induced graft polymerization of acrylonitrile onto porous polyethylene film followed by chemical conversion of the produced cyano group to an amidoxime group. The amidoxime groups were uniformly distributed in the chelating membrane, and the amount of the amidoxime group was 1.8 molkg of the HCl-adsorbed membrane. The membrane was found to adsorb uranyl ion from natural seawater with sufficiently high rate, i.e., 0.85 gkg of adsorbent in 50 days. The concentration factor for uranium was more than 10/sup 5/, and those for magnesium and calcium were less than 10. This adsorbent was stable to the repeated adsorption-elution cycles.
58 citations
TL;DR: In this paper, a chelating membrane containing amidoxime groups for the recovery of uranium was synthesized by the radiation-induced graft polymerization of acrylonitrile onto high and low-density polyethylene films, followed by amidoximation of the cyano groups.
37 citations
TL;DR: In this article, a 1 H and 13 C NMR study of the complexation of citric acid to uranyl ion is reported over a wide pH range (1.3 − 10.3).
33 citations
TL;DR: In this article, the transport of uranyl ions through liquid membranes consisting of tri-n-butylphosphate (TBP) in kerosene oil supported in Celgard 2400 polypropylene microporous film has been studied.
Abstract: Transport of uranyl ions through liquid membranes consisting of tri-n-butylphosphate (TBP) in kerosene oil supported in Celgard 2400 polypropylene microporous film has been studied. Various parameters, such as the effect of nitric acid concentration in the feed solution, TBP concentration in the organic membrane phase, stripping agent concentration and temperature on the flux of uranium across the liquid membrane, have been investigated. The results obtained have been used to elucidate the mechanism of uranium transport and stoichiometry of the diffusing species.
31 citations
01 Mar 1987-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the diffusion coefficients of U(VI) in aqueous uranyl solutions were determined between 293.5 and 311.0 K by comparing the limiting current densities between the copper electrodeposition and the electrolytic reduction of uranyl sulfate under the same hydrodynamic condition.
Abstract: The diffusion coefficients of U(VI) in aqueous uranyl solutions were determined between 293.5 and 311.0 K by comparing the limiting current densities between the copper electrodeposition and the electrolytic reduction of uranyl sulfate under the same hydrodynamic condition. The diffusion coefficients thus determined were almost constant despite the change in agitation speed of electrolyte solutions, which suggests the appropriateness of the method employed in this study. On the other hand, the diffusion coefficients of U(VI) showed a slightly decreasing trend with increase in uranyl sulfate concentration, but when total uranium concentration was kept constant the diffusion coefficient appeared to be almost constant. The activation energies of diffusion coefficients of U(VI) were found to be 21 to 22 kJ mol−1 for the solution studied.
26 citations
TL;DR: The structure of the first U(III) macrocyclic coordinated complex, [U(III)(BH4)2 dicyclohexyl-(18-crown-6)]2U(IV)C15(BH 4) (complex I), has been determined from three dimensional X-ray diffraction data.
25 citations
TL;DR: In this paper, a study of the solvent extraction equilibria of sulphuric acid and uranyl sulphate has been carried out using kerosene solutions of Alamine 336, and a theory based on competing reactions and using mass action has been proposed to describe the observed trends in distribution ratio with pH and organic reagent concentration.
24 citations
TL;DR: In this paper, the new ligands (OCH 3 ) 2 CHHOC 6 H 2 ClCH N(CH 2 ) 2 ] 2 NH, H 2 (NAC), and [UO 2 (SAC)] have been prepared and characterized by infrared, 1 H and 13 C NMR and electronic spectroscopy.
23 citations
Patent•
10 Feb 1987TL;DR: In this article, a process for treating a waste water containing uranium and fluorine comprises a neutralizing precipitation step wherein slaked lime is added to the waste water and precipitate thus formed in separated and removed, and an adsorption step wherein supernatant from the neutralization precipitation step is contacted with a chelating resin which can selectively adsorb fluorine ions and another chelater resin that can selectively adorb uranyl ions to thereby adsorb and remove the fluorine and uranyl ion remaining in the supernatants.
Abstract: A process for treating a waste water containing uranium and fluorine comprises a neutralizing precipitation step wherein slaked lime is added to the waste water containing uranium and fluorine and precipitate thus formed in separated and removed, and an adsorption step wherein supernatant from the neutralizing precipitation step is contacted with a chelating resin which can selectively adsorb fluorine ions and another chelating resin which can selectively adsorb uranyl ions to thereby adsorb and remove the fluorine and uranyl ions remaining in the supernatant. Eluates of the ions adsorbed by the chelating resins and waste liquors for washing and regeneration of these resins are returned to the neutralizing precipitation step. Prior to the neutralizing precipitation step, a decarbonation step may be provided for decomposing carbonate ions, if they are contained in the waste water to be treated.
TL;DR: In this paper, the UO 2 2+ group is maintained in all these complexes with the ligand atoms arranged in the equatorial plane perpendicular to the linear uranyl group, indicating that the ligands function as tetrabasic hexadentate ligands.
TL;DR: In this article, the results indicate that the equilibrium constants of the organic phase addition reaction, log Ks, at 30°C are almost constant, viz., 2.72, 2.69 and 2.84, respectively, for the above three systems.
Abstract: Synergistic extraction of uranyl ion with acylpyrazolones such as 1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5 (HPMTFP, pKa=2.7), 1-phenyl-3-methyl-4-acetylpyrazolone (HPMAP, pKa=3.8) or 1-phenyl-3-methyl-4-benzoylpyrazolone-5 (HPMBP, pKa=4.2) in combination with dicyclohexano-18-crown-6 (DC-18-C6) has been studied at various fixed temperatures. The results indicate that the equilibrium constants of the organic phase addition reaction, log Ks, at 30°C are almost constant, viz., 2.72, 2.69 and 2.84, respectively, for the above three systems. The similarity and low log Ks values with DC-18-C6 as compared with TBP systems with these pyrazolones appears to arise due to the limitation to the approach of the large crown ether molecule in bonding with the uranyl chelate. This is in contrast to the fact that the relative basicities of the two donors (equilibrium constant for nitric acid uptake) are comparable. Thermodynamic data for chelate extraction with HPMTFP evaluated by the temperature coefficient method indicates that a hydrated chelate is extracted into the organic phase. Also, the organic phase addition reaction with DC-18-C6 is stabilized by exothermic enthalpy change, the entropy change counteracting in all the three cases.
TL;DR: It is concluded that the extrahaustorial membrane and haUSTorial plasma membrane are semipermeable in many of the isolated haustorial complexes but that some are damaged during isolation and purification procedures; that a barrier to diffusion exists where the extra exhaustorial membrane is joined to the wall of the haustors neck and in other parts of the neck wall so that the whole boundary of the extrahaulorial matrix restricts diffusion of solutes.
TL;DR: In this article, the UO 2 2+ cation was shown to interact with two D-fructose molecules through O2, O3 of the first and O4, O5 of the second sugar moiety, resulting into a sixcoordination geometry around the uranium ion.
TL;DR: 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 M(m)L(n) species formed in solution, and the constants for the hydrolysis and polymeric complexes.
TL;DR: A laser-induced fluorescence method (LFM) is described for determination of trace amounts of uranium(VI), with a detection limit of 4 x 10(-11) g/ml, using a repetitive pulsed laser, time discrimination and an averaging technique.
TL;DR: In this paper, a dioxouranium (VI) complex with the dibasic tridentate 7-carboxaldehyde-8-hydroxyquinoline-aroylhydrazone derivatives was synthesized and is bonded to the axial oxygen of the uranyl moiety and is easily substituted by dimethylsulphoxide.
Abstract: New dioxouranium(VI) complexes with the dibasic tridentate 7-carboxaldehyde-8-hydroxyquinoline-aroylhydrazone derivatives (1), have synthesized and is bonded to the axial oxygen of the uranyl moiety and is easily substituted by dimethylsulphoxide. The ligands contain intramolecular hydrogen bonds, one of which is from the enolic form of the hydrazone residue. The1H n.m.r. spectra show that the position of the hydrogenbonded proton of the hydrazone moiety is substituent dependent. The F(U−O) (mydn/A) and the bond length r(U−O) (A) of the UO bond are calculated from the i.r. data and related to the electronic properties of the substituents.
TL;DR: In this paper, the effect of sttrring rate, nitric acid concentration and TOA concentration in the organic membrane phase, on the flux of uranyl ions through the membrane has been studied.
Abstract: Tri-n-octylamine (TOA) dissolved in xylene has been used as carrier, constituting liquid membrane supported in Celgard 2400 polypropylene microporous film for the transport of uranyl ions against their concentration gradient from aqueous acid solutions to an alkaline aqueous phase. Effect of sttrring rate, nitric acid concentration and TOA concentration in the organic membrane phase, on the flux of uranyl ions through the membrane has been studied. Viscosity and density data have been obtained to estimate diffusion coefficients and hence the permeability coefficients to compare the same with experimental values, using distribution coefficient data, measured from solvent extraction experiments and available in the literature. Analysis of the flux data has been performed to study the stoichiometry of the chemical reaction involved in complex formation reaction. The results have been compared with simple liquid-liquid extraction data.
TL;DR: The structure of dioxobis (2,4-pentanedionato)(pyridine)uranium(VI) is described in this article, where two rings are twisted inwards towards each other about this plane, whilst the other two are directed above and below, and are twisted away from each other, forming a cavity into which the pyridine ring nests.
Abstract: Bis(1,3-diphenyl-l,3-propanedionato)oxo- (pyridine)uranium(VI) (1), (UO2(CasHllO2)2(CsHsN)), Mr= 795.6, monoclinic, P2Jn, a= 10.158 (2), b= 21.937 (8), c= 13.888 (4)A, t= 103.49 (1) ° , U = 3009 (2)/k 3, Z = 4, D x = 1.76 g cm -3, 2(Mo Ka) = 0.71069 A, /t = 51.48 cm -1, F(000) = 1536, T= 289 K, R = 0.036 for 3269 unique observed reflec- tions. Bis( 1-(tert-butoxy)- 1,3-butanedionato)dioxo- (pyridine)uranium(IV) (2), (UO2(CaHI303)2(CsHsN)), M r= 663.5, orthorhombic, Cmc2~, a = 15.939 (9), b = 19.532 (8), c= 9.777 (6) A, U= 3044 (1) A 3, Z = 4, D x = 1.45 gcm -a, 2(Mo Kct) = 0.71069/~, /t = 50.81 cm -1, F(000) = 1280, T= 289 K, R = 0.048 for 1178 unique observed reflections. Dioxobis(2,4-pen- tanedionato)(pyridine)neptunium(VI) (3), (NpO2(CsH 7- O2)2(CsHsN)), Mr=546.4, orthorhombic, Fdd2, a = 29.617 (5), b= 11.406 (2), c= 10.595 (4)A, U= 3579 (2) A 3, Z=8, D x=2.03gcm -3, 2(MoKa)= 0.71069 A, /a= 37.95 cm -~, F(000) = 2056, T= 173 K, R = 0.046 for 625 unique observed reflections. The bond angle of 177-9 (2) ° for (1) indicates a very slightly non-linear uranyl group. The neptunyl bond in complex (3) is slightly more distorted (176.5 (19)o), whilst in complex (2) the uranyl group deviates even more from linearity (175.8 (8)°). In (1), the phenyl groups are displaced out of the equatorial plane. Two rings are twisted inwards towards each other about this plane, whilst the other two are directed above and below, and are twisted away from each other, forming a cavity into which the pyridine ring nestles. The methyl groups of the tert-butoxy moiety in complex (2) and those of the 2,4-pentanedione ligand in (3) are displaced above and below the equatorial plane. The pyridine molecule of (2) is perpendicular to the equatorial plane, while those of (1) and (3) are set obliquely (dihedral angles 36.9 (2) and 49.0 (2)°). Introduction. We have previously reported the structure of dioxobis (2,4-pentanedionato)(pyridine)uranium(VI)
TL;DR: In this article, a series of nine complexes of uranyl nitrate with some Schiff bases derived from 4-aminoantipyrine and certain carbonyl compounds, such as benzaldehyde, 2-nitrobenzaldehyde, 3-naphthaldehyde, 4- methylbenzinaldehyde, N, N -dimethylaminobenzaldehyde and 2-hydroxy benzaldehyde have been synthesized, and the proposed general formula for the complexes suggests that the uranyl ion has a coordination number of eight in addition to the two oxygen atoms which have already been
TL;DR: In this article, the same authors have shown that the entropy values for sulfoxides with eight or more carbon atoms are much more negative as compared to the lower sulfoxide and are also in contrast to HTTA and BTFA systems with these sulfoxide compounds.
Abstract: Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoyl pyrazolone-5 (HPMBP) and aliphatic sulfoxides of varying basicities, viz di-isoamyl (DIASO), di-n-hexyl (DHSO), di-n-septyl (DSSO), di-n-octyl (DOSO), di-n-nonyl (DNSO), di-n-decyl (DDSO) or di-n-undecyl (DuDSO) sulfoxide has been studied at 30±0.1°C. Extraction with some of these sulfoxides has been studied at various fixed temperatures also. The organic phase equilibrium constant (log Ks) has been found to increase with the basicity of the sulfoxide up to DOSO beyond which there is a gradual decreasing trend which has been attributed to the effect of possible steric hindrance (spatial) involved in the bonding of the higher sulfoxides (greater than 8 carbon atoms) with UO2 (PMBP)2 chelate. This has been supported by thermodynamic data involved in these systems. The entropy values for sulfoxides with eight or more carbon atoms are much more negative as compared to the lower sulfoxides and are also in contrast to HTTA and BTFA systems with these sulfoxides studied earlier.
Patent•
30 Dec 1987TL;DR: In this article, a method of fabricating uranium dioxide (UO2) powder from uranium hexafluoride (UF6) is disclosed, which comprises (1) reacting UF6 gas with steam with controlling the temperature of reaction between said UO2 gas and said steam at a predetermined temperature within the range of 200° to 700° C., to form solid uranyl fluoride (UOLF) and/or uranium oxide with an O/U ratio (oxygen-to-uranium atomic ratio) of 2.7 to 3, dissolving said U
Abstract: A method of fabricating uranium dioxide (UO2) powder from uranium hexafluoride (UF6) is disclosed, which comprises (1) reacting UF6 gas with steam with controlling the temperature of reaction between said UF6 gas and said steam at a predetermined temperature within the range of 200° to 700° C., to form solid uranyl fluoride (UO2 F2) and/or uranium oxide with an O/U ratio (oxygen-to-uranium atomic ratio) of 2.7 to 3, (2) dissolving said UO2 F2 and/or uranium oxide in water or nitric acid to form an aqueous uranyl solution containing UO2 F2 and/or uranyl nitrate (UO2 (NO3)2), (3) reacting said aqueous uranyl solution with ammonia to precipitate ammonium diuranate (ADU), (4) filtering said precipitate, (5) drying said precipitate, (6) calcining said dry precipitate, and (7) reducing said calcined precipitate, whereby controlling the characteristics of said UO2 powder.
TL;DR: In this article, UO2(NO3)2(Hbmmppt)·acetone was characterized by elemental analysis and spectroscopic methods, and the corresponding anions were obtained from the reaction of 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (HBMppt), the 3-one analogue (Hbmppt).
TL;DR: In this article, the authors determined the apparent fractional dimensionality of four crystalline uranyl-exchanged zeolites from the observed decay of the uranyl ion(donor)emission in the presence of europium ions as acceptors and found that the zeolite with the lowest dimensionality is the most effective in the photocatalytical conversion of isopropyl alcohol to acetone.
Abstract: The temporal behavior of the intensity of an energy donor in the presence of energy acceptors distributed over a disordered lattice with dilation symmetry is predicted to give information about its fractal dimensionality. Using calculation and simulation, the authors have recently shown that the same procedure gives an apparent fractional dimensionality for lattices with translational symmetry possessing excluded volumes. In this letter, they have experimentally determined the apparent fractional dimensionality of four crystalline uranyl-exchanged zeolites from the observed decay of the uranyl ion(donor)emission in the presence of europium ions as acceptors. While no correlation is observed between the fractional dimensionality and the fraction of void or the energy-transfer efficiency on these four lattices, it is found that the zeolite with the lowest dimensionality is the most effective in the photocatalytical conversion of isopropyl alcohol to acetone.
TL;DR: In this article, an electron transfer mechanism was proposed for the formation of uranium(V) which disproportionates into uranium(IV) and uranium(VI) in aqueous acidic media.
TL;DR: In this paper, a complex of uranyl ion with 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 (PMAP) and various oxo-donors such as aliphatic sulphoxides [R2SO] was synthesized and characterized.
Patent•
06 Mar 1987TL;DR: In this paper, a uranyl ion selective electrode having a respon-sive membrane, an inner reference electrode, and an inner solution is disclosed, in which the responsive membrane is obtained by treating a membrane material with an ion-exchanger comprising at least one uranyl ions complex formed between a neutral phosphoric ester or neutral phosphorous ester as a complexing agent, and a solvent mediator having affinity for the membrane material.
Abstract: OF THE DISCLOSURE A uranyl ion selective electrode having a respon-sive membrane, an inner reference electrode, and a uranyl ion inner solution is disclosed, in which the responsive membrane is obtained by treating a membrane material with an ion-exchanger comprising at least one uranyl ion complex formed between a uranyl ion and a neutral phosphoric ester or a neutral phosphorous ester as a complexing agent, a diluent excellent in compatibility with the ion-exchanger, and a solvent mediator having affinity for the membrane material. The electrode is excel-lent in concentration responsiveness, reproducibility, accuracy, and durability and is particularly suitable for use in uranyl ion analysis in the atomic energy industry.
TL;DR: In this article, a series of dioxouranium(VI) complexes of a potential ONNO tetradentate donor 2-aminobenzoylhydrazone of butane-2,3-dione (L1H2) have been synthesized.
Abstract: A new series of dioxouranium(VI) complexes of a potential ONNO tetradentate donor 2-aminobenzoylhydrazone of butane-2,3-dione (L1H2) have been synthesized. At pH 2·5–4·0, the donor (L1H2) reacts in the keto form and complexes of the type [UO2(L1H2)(X)2] (X−=Cl−, Br−, NO
3
−
, NCS−, ClO
4
−
, CH3COO−, 1/2SO
4
2−
) are obtained. At higher pH (6·5–7), the complex of the enol form having the formula [UO2(L1)(H2O)] has been isolated. On reaction with a monodentate lewis base (B), both types of complexes yield adducts of the type [UO2(L1)(B)]. All these complexes have been characterised adequately by elemental analyses and other standard physicochemical techniques. Location of the bonding sites of the donor molecule around the uranyl ion, status of the uranium-oxygen bond and the probable structure of the complexes have also been discussed.