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Showing papers on "Uranyl published in 1981"


Journal ArticleDOI
TL;DR: In this article, the binding of tracer level UO 2 +2 to a soil humic acid was measured by a solvent extraction technique, and the binding was interpreted as involving only the carboxylate groups of the humate and both 1:1 and 1:2 UO2 +2 : CO 2 − binding was observed.

108 citations


Journal ArticleDOI
TL;DR: In this paper, the results showed that the adsorption isotherms of uranyl ions on the clay followed Lang- muir-type curves with increasing concentration of uranium.
Abstract: Wyoming montmorillonite, <2-/xm particle size, saturated with Na, K, Mg, Ca, and Ba ions, was reacted with uranyl nitrate solutions in the concentration range 1-300 ppm uranium. With constant amounts of clay and solution volume, the adsorption isotherms of uranyl ions on the clay followed Lang- muir-type curves with increasing concentration of uranium. The maximum adsorption derived from linear Langmuir plots corresponds to the exchange capacity of the clay. Experiments with solutions of constant volume and constant ionicity, but with variable proportions of uranyl and other cations, showed that uranyl ions were strongly preferred by the clay to Na + and K +, but less strongly than Mg 2+, Ca 2+, and Ba 2+. Chemical analyses of uranyl montmorillonites prepared with nitrate solutions, 0.05 M and pH - 2.0, gave interlayer cations (UO2)0.094Ho.l~. Addition of NaOH to the uranyl nitrate solution to increase the pH to 4.0 gave a montmorillonite with interlayer cations (UOz)0.083Na0.12H0.04. A fully exchanged uranyl mont- morillonite was prepared with 0.05 M uranyl acetate solution, pH - 4.0, followed by further treatment with 1.25 x 10 -5 M solution, pH - 4.5. The resulting interlayer composition was (UO2)0.i9(H20)H5 which corresponds with the hexahydrate ion, l(UO2)" 6H2Ol. X-ray powder diffraction and thermal dam are re- corded for the fully exchanged uranyl montmorillonite.

98 citations


Journal ArticleDOI
TL;DR: In this paper, the Raman spectra of aqueous uranyl ion have been measured as a function of pH and uranyl concentration, and the symmetric stretching vibration has been found to consist of three bands at 869, 851, and 836 cm/sup -1/ which are identified as belonging to the UO/sub 2/sup 2 +/ ions, respectively.
Abstract: Raman spectra of aqueous uranyl ion have been neasured as a function of pH and uranyl concentration. The ..nu../sub 1/ symmetrical stretching vibration has been found to consist of three bands at 869, 851, and 836 cm/sup -1/ which are identified as belonging to the UO/sub 2//sup 2 +/, (UO/sub 2/)/sub 2/(OH)/sub 2//sup 2 +/, and (UO/sub 2/)/sub 3/(OH)/sub 5//sup +/ ions, respectively. The Raman spectral measurements correlate with equilibrium thermodynamic measurements.

94 citations


Journal Article
TL;DR: A triclinic uranyl silicate mineral was discovered during this study, although there is not enough sample to describe it adequately as mentioned in this paper. But the locations of the uranium atoms in this structure indicate that it may not be composed of uranyl-silicate chains such as those found in all the other uranium silicate minerals.
Abstract: The uranyl silicate minerals have been divided into three groups on the basis of their uranium to silicon ratios. The 1:1 group includes uranophane, beta-uranophane, boltwoodite, sodium boltwoodite, kasolite, sklodowskite, and cuprosklodowskite. A structure refinement of uranophane, a structure determination of boltwoodite, and previously reported structure determinations of most of these minerals indicate that they are composed of uranyl silicate chains made of edge-shared uranium pentagonal bipyramidal groups and silicate tetrahedra. These chains have the composition ((UO/sub 2/)(SiO/sub 4/))/sub n/sup /sup -2/n/ and are crossliked by a bridging oxygen atom to form a uranyl silicate sheet. These sheets are crossbonded by the additional cations in the structure. The uranyl minerals with a uranium to silicon ratio of 1:3 include weeksite and haiweeite. A partial structure analysis of weeksite suggests that the structure type for this group consists of uranyl silicate chains, similar to those found in the 1:1 group, that are crosslinked by the additional silicate tetrahedra in the structure. The uranyl mineral group with a uranium to silicon ratio of 2:1 contains only the mineral soddyite. This structure is composed of uranyl silicate chains that are crossbonded by sharing a common silicon to give a three-dimensional framework structure. Amore » new triclinic uranyl silicate mineral was discovered during this study, although there is not enough sample to describe it adequately. The locations of the uranium atoms in this structure indicate that it may not be composed of uranyl silicate chains such as those found in all the other uranyl silicate minerals.« less

88 citations


Journal ArticleDOI
TL;DR: In this paper, the first reported peroxo complexes of uranium which contain organic moieties were described, and they were found to be unusually stable and relatively unreactive, and were used as oxidants in organic synthesis.
Abstract: Peroxo complexes of molybdenum and tungsten are attracting interest as oxidants in organic synthesis. As uranium somewhat resembles the group 6B elements, it was of interest to discover whether it would form analogous peroxo complexes which contain organic moieties. The preeminence of the UO/sub 2/ grouping distinguishes uranium from molybdenum and tungsten, however, and this factor may have hitherto prevented the generation of peroxo complexes from uranyl salts and organic reagents. The present paper describes the isolation and characterization of novel mono- and diperoxo complexes. These are found to be unusually stable, and they are relatively unreactive. They are the first reported examples of peroxo complexes of uranium which contain organic moieties.

75 citations


Journal ArticleDOI
TL;DR: The Raman spectra of a number of uranyl species in carbonate and alkaline solutions have been obtained as well as those of solids obtained from carbonate media as discussed by the authors.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water.
Abstract: The adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid during the first 10 min and was affected by pH of the solution, temperature, granule radius and the co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate.

53 citations


Journal ArticleDOI
TL;DR: The remote sensing of laser-induced uranyl ion fluorescence is examined as a potential indicator of uranium occurring in geologic materials at the earth's surface and the lifetime and brightness of the fluorescence from a wide variety of rocks, minerals, and soils are reported.
Abstract: The remote sensing of laser-induced uranyl ion fluorescence is examined as a potential indicator of uranium occurring in geologic materials at the earth’s surface. The lifetime and brightness of the fluorescence from a wide variety of rocks, minerals, and soils are reported. The distinctive characteristics of uranyl ion absorption and fluorescence were observed in diverse geologic materials such as chalcedonies and opals containing 15–3000 ppm of uranium and in surface coatings of uranyl minerals such as metaautunite, liebigite, and andersonite. The conditions which permit the excitation and selective detection of uranyl ion fluorescence from such targets are described.

50 citations


Journal ArticleDOI
TL;DR: In this article, a pulsed-lamp phosphorimeter was used to reject interference from organic fluorescence and to determine the alterations in spectra, intensities, and lifetimes produced by the addition of enhancers or quenchers.
Abstract: Phosphorescence from aqueous uranyl ions is examined with a pulsed-lamp phosphorimeter to reject interference from organic fluorescence and to determine the alterations in spectra, intensities, and lifetimes produced by the addition of enhancers or quenchers. Detection limits range from 100 parts per million (ppM) to 10 parts per trillion (pptr). Deviations from strict exponential decay are also discussed.

50 citations


Journal ArticleDOI
01 Feb 1981-Talanta
TL;DR: A sensitive and selective technique for the detection and assay of the uranyl ion is described and is based upon the measurement of the lumi.

31 citations


Journal ArticleDOI
TL;DR: In this paper, the solvent extraction of heptavalent technetium from aqueous nitric or hydrochloric acid by tributyl phosphate in n-dodecane (TBP-NDD) has been studied over a wide range of TBP and acid concentrations at 25, 50, and 60°C.
Abstract: The solvent extraction of heptavalent technetium from aqueous nitric or hydrochloric acid by tributyl phosphate in n-dodecane (TBP-NDD) has been studied over a wide range of TBP and acid concentrations at 25, 50, and 60°C. The extraction was found to proceed according to the reaction 3TBP + H+ + TcO4 − → (HTcO4 · 3TBP). A discussion of possible reaction mechanisms is presented, along with values for ΔG, ΔH, ΔS, and the equilibrium constant for the extraction reaction. Finally, evidence for the coextraction of technetium by uranyl ions is discussed.

Journal ArticleDOI
TL;DR: The /sup 13/C NMR identification of the uranyl tricarbonate complex (important in solution mining of U from ore and conventional carbonate leaching) is reported in this paper.
Abstract: The /sup 13/C NMR identification of the uranyl tricarbonate complex (important in solution mining of U from ore and conventional carbonate leaching) is reported. The NMR spectra show the transition from slow to fast carbonate exchange between uranyl ion and bulk water in an accessible temperature range. The taller NMR peak at 162.31 ppM is frm HCO/sub 3//sup -/ and the smaller peak at 168.86 ppM is from the uranyl tricarbonate complex. (DLC)

Journal ArticleDOI
TL;DR: In this paper, the sorption site densities calculated from saturation capacities, evaluated from Langmuir adsorption isotherm and surface areas, bear a direct relationship with the heat of sorption values.

Journal ArticleDOI
TL;DR: In this paper, the formation of the Am(V)-U(VI) complex obeys the mass action law and the constant of complexation was calculated to be K = 0.095 ± 0.030.

Book ChapterDOI
TL;DR: In this paper, various ratios of Eu and UO2 acetates were prepared by dissolving Eu in acetic acid and removing acetic acids in vacuum, and fluorescence intensities at 616 nm were measured under excitation at wavelength of 429 nm.
Abstract: Various ratios of Eu and UO2 acetates were prepared by dissolving Eu and UO2 acetates in acetic acid and removing acetic acid in vacuum. The fluorescence intensities at 616 nm of these mixed acetates were measured under excitation at wavelength of 429 nm. Strong energy transfer from UO 2 2+ to Eu3+ was observed. This result indicated that these ions were in very close contact in this system. Various concentrations of Eu3+ and UO 2 2+ salts of polymers containing carboxyl ligands were prepared and fluorescence properties of these polymers were investigated. The polymers investigated were poly (methacrylic acid) (PMA), and copolymers of styrene-acrylic acid (PSAA) and methyl methacrylate-methacrylic acid (PMM/MA). When Eu3+ and UO 2 2+ were introduced to the polymers of PSAA and PMM/MA, very effective energy transfer from UO 2 2+ to Eu3+ was observed because of the proximity of these metal ions in ionic aggregates of these ionomers. However, the PMA-UO2 and Eu salts did not show energy transfer even when a large excess of UO2+ 2 was added to the polymer. The PMA salts are reported to have no ion aggregate structure; it is concluded that Eu3+ and UO 2 2+ ions were uniformly dispersed throughout the polymer system so that the distances between these ions were far beyond the energy transfer range.

Journal ArticleDOI
TL;DR: In this paper, the title compound has been prepared and crystallized from acetonitrile, and the structure was determined from MoKα diffractometer data by standard methods and refined to R = 0.066.

Journal Article
TL;DR: The low inherent toxicity of Tiron may make it appropriate for possible clinical application and survival rates for animals receiving multiple injections of T iron were enhanced over those receiving Na3CaDTPA.
Abstract: Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) administered intraperitoneally was found to antagonize the lethal action of intraperitoneally induced uranium(VI) toxicity. In a comparative study Tiron was evaluated against Na3CaDTPA (sodium calcium diethylenetriaminepentaacetate). The ability of these compounds to detoxify the uranyl ion in simple and complexed form and their efficacy in delayed treatment regimens and determined. Toxicities of the complexes were assessed by the administration of uranyl acetate at levels of 40 mg/kg or 80 mg/kg complexed at a mole ratio of 3:1 or 2:1 of chelating agent to uranium, prior to injection, followed by two additional doses of chelating agent given one and three hours later at a 10:1 mole ratio of chelating agent to uranium. Therapy in delayed treatment regimens consisted of three injections of antidote given 20 minutes, one hour, and three hours, at a 10:1 mole ratio of chelating agent to uranium, subsequent to an injection of 40 mg/kg uranyl acetate. Survival rates for animals receiving multiple injections of Tiron were enhanced over those receiving Na3CaDTPA. The low inherent toxicity of Tiron may make it appropriate for possible clinical application.

Journal ArticleDOI
TL;DR: In this article, the complex UO/sub 2/(NO/sub 3/)/sub 2/O with tri-n-butylphosphine oxide was analyzed by single-crystal x-ray diffraction methods.
Abstract: The complex UO/sub 2/(NO/sub 3/)/sub 2/((C/sub 4/H/sub 9/)/sub 3/PO)/sub 2/, made by reacting UO/sub 2/(NO/sub 3/)/sub 2/.6H/sub 2/O with tri-n-butylphosphine oxide, was analyzed by single-crystal x-ray diffraction methods. The monoclinic unit cell has a = 8.496 (2) A, b = 29.630 (7) A, c = 14.063 (3) A, and ..beta.. = 94.92 (2)/sup 0/ at 23/sup 0/C; the space group is C2/c, and Z = 4. The structure was determined by the heavy-atom method and refined by least squares. Positions and anisotropic thermal parameters were adjusted for 22 nonhydrogen atoms, while hydrogen atoms were fixed in assumed positions; the agreement factor, R/sub F/, reached 0.043 for 1648 observations (> 3sigma). There are discrete molecules in the crystal consisting of uranyl ions surrounded at the equator by six oxygen atoms furnished by two bidentate nitrate ions and two tri-n-butylphosphine oxide molecules. Two of the n-butyl groups are anti and one is gauche in conformation. The bond between the phosphine oxide and the uranium atom is shorter than the corresponding water to uranium bond in each of two structurally analogous hydrates.

Journal ArticleDOI
TL;DR: Uranyl sulfate is a negative stain of high quality for electron microscopy of macromolecules below their isoelectric point as mentioned in this paper, which results in good contrast and high resolution as demonstrated by optical diffraction of periodic structure.
Abstract: Uranyl sulphate is a negative stain of high quality for electron microscopy of macromolecules below their isoelectric point. The stain results in good contrast and high resolution as demonstrated by optical diffraction of periodic structure. Analysis of scanning transmission electron microscopic data reveals that uranyl sulphate is lower in background noise level than uranyl acetate and is dramatically more resistant toward granularization upon continued exposure to electron irradiation.

Journal ArticleDOI
TL;DR: In this article, the four lowest excited states have B2g, B3g, Ag and B1g symmetry in D2h symmetry, analogous to the corresponding states in Cs2UOO2Cl4.
Abstract: Raman, polarised infrared, electronic absorption and luminescence spectra of [Me4N]2UO2Cl4 have been measured at temperatures down to 10 K. The four lowest excited states have B2g, B3g, Ag and B1g symmetry in D2h symmetry. These are analogous to the corresponding states in Cs2UO2Cl4. The crystals readily absorb water from laboratory air with the creation of non-equivalent uranyl sites. A previous interpretation of the spectra of this compound is incorrect.

Journal ArticleDOI
TL;DR: In this paper, an intermediate state adsorption model analogous to a kinetic model based on an enzyme - substrate coupling scheme was proposed to estimate correlative mass transfer coefficients with a constant transfer coefficient relating the rate of transfer to the concentration gradient.

Journal ArticleDOI
TL;DR: In this article, the luminescence spectra of crystals of M3UO2F5 (M=Cs, Rb, K, Na and NH4) were measured at temperatures down to 4 K.
Abstract: The luminescence spectra of crystals of M3UO2F5 (M=Cs, Rb, K, Na and NH4) and the polarized absorption spectrum of K3UO2F5 have been measured at temperatures down to 4 K. The lowest excited states have E″1 and E′2 (D 5h ) symmetry, as expected from the model of Denning. The E″1↔A′1 electronic origins are intense, due to the low site symmetry of the uranyl ion. At least four of the six possible vibronic origins due to internal motions of the UO2F5 3- ion are identified. Strong progressions in v 1[vs(O-U-O)] and weak progressions in v 2[vs(U-F)] are based on these vibronic origins. The spectra are compared with those of the D 4h anion UO2Cl4 2-.

Journal ArticleDOI
TL;DR: In this paper, it was shown that energy transfer from uranyl to europium perchlorates is pH dependent, and that the uranyl species involved is not the UO/sub 2/sup 2 +/ ion itself but one or more of the hydrolytic species.
Abstract: Fluorescence measurements on aqueous solutions containing uranyl(VI) and europium(III) perchlorates have shown that energy transfer from uranyl to europium is pH dependent. The uranyl species involved is not the UO/sub 2//sup 2 +/ ion itself but one or more of the hydrolytic species. Emission spectra of the europium ion in the presence of uranyl indicate the formation of a complex between the lanthanide ion and the hydrolyzed uranyl species. The relative intensities of the europium emission lines, the energy-transfer efficiency and the dependence of energy transfer on concentrations are all consistent with a mechanism which involves this complex.


Journal ArticleDOI
TL;DR: Perry as mentioned in this paper described an AIR-STABLE class of URANYL MONOTHIOCCARAMATE ALKOXIDES, an air-stable class of ALKXIDES.

Journal ArticleDOI
TL;DR: In this paper, the synthesis and crystal structure of the title compound are described, and the structure was solved by the heavy-atom method from 1252 counter reflections, and refined by least-squares methods to R 0.054.

Journal ArticleDOI
TL;DR: In this paper, the distribution of heavy metal ions in the intracellular soluble fraction was investigated in detail by gel filtration, which showed that copper ion was present in both the high and low molecular weight fractions, while cadmium and uranyl ions were present only in the high molecular weight fraction.
Abstract: Experiments were undertaken to determine whether the distribution of copper, cadmium, and uranyl ions in Chlorella cells differed with different heavy metal ions. The amounts of these three metals in each cell fraction were in the following decreasing order: intracellular soluble fraction > intracellular particle fraction >> cell wall fraction. Heavy metal ions were found most abundantly in the intracellular soluble fraction and only 3-5% of the heavy metal ions were in the cell wall fraction. The distribution of uranyl ion in Chlorella cells differed from both that of copper ion and cadmium ion. The distribution of heavy metal ions in the intracellular soluble fraction was investigated in detail by gel filtration, which showed that copper ion was present in both the high and low molecular weight fractions, while cadmium and uranyl ions were present only in the high molecular weight fraction. These results indicated that substances combined with heavy metal ions in Chlorella cells differed with different heavy metal ions. Next, the chemical state of cupric ion absorbed in cells was studied in detail using ESR. The values of g¦¦ and |A¦¦(Cu)| of cupric ion showedthat cupric ion was coordinated by two nitrogen and two oxygen atoms.

Journal ArticleDOI
TL;DR: In this article, a substoichiometric extraction of uranyl ion in a synergic system of a chelating reagent and a neutral ligand is described, which is applicable to > ca. 10 μg of uranium.

Journal ArticleDOI
TL;DR: Some 1∵1, 2∵3, and 1∶2 uranyl complexes of salicylaldehyde-2-hydroxyanil (H2SAP) and its substituted (3-methoxy-, 5-nitro, 5-chloro- and 3,5-dichloro-) derivatives have been synthesized and characterized.
Abstract: Some 1∶1, 2∶3, and 1∶2 uranyl complexes of salicylaldehyde-2-hydroxyanil (H2SAP) and its substituted (3-methoxy-, 5-nitro-, 5-chloro- and 3,5-dichloro-) derivatives have been synthesized and characterized. The conductivity, i.r.,1H n.m.r. and visible spectroscopic data allow discussion of the varying ligating behaviour of the potentially dibasic tridentate Schiff base ligands toward dioxouranium(VI).

Journal ArticleDOI
TL;DR: The chelated uranylhexafluoroacetylacetonate ion forms adducts with Lewis bases which are fluxional when studied by /sup 19/F NMR.
Abstract: The chelated uranylhexafluoroacetylacetonate ion forms adducts with Lewis bases which are fluxional when studied by /sup 19/F NMR. The compounds have a pentagonal-bipyramidal geometry in which the base occupies one site in the equatorial ring. The kinetic parameters suggest that the equilibrating process is one in which the base migrates to a complementary site on the other side of the uranyl ion via intermediate capped octahedral structures.