Uranyl Sulfate Research Articles

18-Electron rule and structure of uranyl sulfate complexes

Characteristics of the Voronoi-Dirichlet polyhedra were used to perform the crystal-chemical analysis of all known sulfate-containing uranyl compounds. The effect of the type of coordination of sulfate ions by U(VI) atoms on the characteristics of S-O and U-O bonds in the crystal structure is considered. The electrondonor properties of sulfate ions were estimated quantitatively on the basis of the 18-electron rule. Some predictive properties of the stereoatomic crystal structure model were demonstrated in relation to tri-and tetrasulfatouranylates.

Comparison between two commercial uranium resins and a uranyl sulphate imprinted resin based on self-assembling MIT

In recent years, resins prepared via molecular imprinting technology have received considerable attention owing to their recognition and selective adsorption. This paper deals with the comparative investigation between a uranyl sulphate imprinted ion-exchange based on self-assembling molecular imprinting technology and two kinds of commercial uranium resins (the medium pore resin D263 and strong base resin 201 × 7). The studies were focused on their kinetics performance, adaptability toward pH, and performance of saturation and elution in laboratory-scale column. The results show that the imprinted ion exchange resin has the fast kinetics, high adaptability toward pH, and good adsorption and elution performance.

Structure Determination and Infrared Spectroscopy of K(UO2)(SO4)(OH)(H2O) and K(UO2)(SO4)(OH)

Two potassium uranyl sulfate compounds were synthesized, and their crystal structures were determined by single-crystal X-ray diffraction. K(UO2)(SO4)(OH)(H2O) (KUS1) crystallizes in space group P21/c, a = 8.0521(4) A, b = 7.9354(4) A, c = 11.3177(6) A, beta = 107.6780(10) degrees , V = 689.01(6) A3, and Z = 4. K(UO2)(SO4)(OH) (KUS2) is orthorhombic Pbca, a = 8.4451(2) A, b = 10.8058(4) A, c = 13.5406(5)A, V = 1235.66(7)A3, and Z = 8. Both structures were refined on the basis of F2 for all unique data collected with Mo Kalpha radiation and a CCD-based detector to agreement indices R1 = 0.0251 and 0.0206 calculated for 2856 and 2616 reflections for KUS1 and KUS2, respectively. The structures contain vertex-sharing uranyl pentagonal bipyramids and sulfate tetrahedra linked into new chains and sheet topologies. Infrared spectroscopy provides additional information about the linkages between the sulfate and uranyl polyhedra, as well as the hydrogen bonding present in the structures. The U-O-S connectivity is examined in detail, and the local bond angle is impacted by the steric constraints of the crystal structure.

On the structure and relative stability of uranyl(VI) sulfate complexes in solution

The mode of coordination, mono-, bidentate, sulfate in UO2(SO4) and UO2(SO4)(2) (2-), and the relative energy of the various isomers have been studied at the DFT and MP2 levels using DFT-optimized ...

Crystal structure of the UO2SO4 · 2SO(CH3)2 compound: A new type of uranyl sulfate ribbons and the UO2SO4 · 2SO (CH3)2-UO2SO4 · 2CO(NH2)2 morphotropic transition

Single crystals of bis(dimethyl sulfoxide) uranyl sulfate are prepared, and their crystal structure is determined using X-ray diffraction analysis. The crystals are monoclinic, space group P21/c, a = 12.9189(8) A, b = 7.9008(5) A, c = 12.1405(7) A, β = 95.677(1)°, R1 = 0.0216, wR2 = 0.0468 for 2761 unique reflections with F > 2σ(F). The crystal structure of the UO2SO4 · 2Dmso compound (where Dmso is dimethyl sulfoxide) is built up of infinite uncharged ribbons of the composition [UO2SO4 · 2Dmso]∞, in which the SO4 tetrahedron is tridentately coordinated to two uranyl groups. The differences between the structures of the uranyl sulfate compounds formed upon replacement of dimethyl sulfoxide by other molecules are considered.

Raman spectroscopic study of the molecular structure of the uranyl mineral zippeite from Jáchymov (Joachimsthal), Czech Republic

Raman spectra at 298 and 77 K and infrared spectra of the uranyl sulfate mineral zippeite from Jáchymov (Joachimsthal), Czech Republic, K 0.6(H 3O) 0.4[(UO 2) 6(SO 4) 3(OH) 7]·8H 2O, were studied. Observed bands were tentatively attributed to the (UO 2) 2+ and (SO 4) 2− stretching and bending vibrations, the OH stretching vibrations of water molecules, hydroxyls and oxonium ions, and H 2O, oxonium, and δ U–OH bending vibrations. Empirical relations were used for the calculation of U–O bond lengths in uranyl R (Å) = f( ν 3 or ν 1(UO 2) 2+). Calculated U–O bond lengths are in agreement with U–O bond lengths from the single crystal structure analysis and those inferred for uranyl anion sheet topology of uranyl pentagonal dipyramidal coordination polyhedra. The number of observed bands supports the conclusion from single crystal structure analysis that at least two symmetrically distinct U 6+ (in uranyls) and S 6+ (in sulfates), water molecules and hydroxyls may be present in the crystal structure of the zippeite studied. Strong to very weak hydrogen bonds present in the crystal structure of zippeite studied were inferred from the IR spectra.

Pseudojohannite from Jachymov, Musonoi, and La Creusaz: A new member of the zippeite-group

Pseudojohannite is a hydrated copper(II) uranyl sulfate described from Jachymov, Northern Bohemia, Czech Republic (type locality). Pseudojohannite also occurs at the Musonoi quarry near Kolwezi, Shaba, Congo, and the La Creusaz prospect, Western Swiss Alps. At all three localities, pseudojohannite formed through the interaction of acid sulfate mine drainage waters with uraninite (Jachymov and La Creusaz) or uranyl silicates (Musonoi). Pseudojohannite forms moss green, non UV-fluorescent aggregates consisting of irregularly shaped crystals measuring up to 25 μm in length and displaying an excellent cleavage parallel to (101). d meas is 4.31 g/cm 3 , d calc 4.38 g/cm 3 , and the refractive indices are n min = 1.725 and n max = 1.740. A high-resolution synchrotron powder diffraction pattern on the material from Musonoi shows that pseudojohannite is triclinic ( P 1 or P 1), with a = 10.027(1) A, b = 10.822(1) A, c = 13.396(1) A, α = 87.97(1)°, β = 109.20(1)°, γ = 90.89(1)°, V = 1371.9(5) A 3 . The location of the uranium and sulfur atoms in the cell was obtained by direct methods using 1807 reflections extracted from the powder diffractogram. Pseudojohannite contains zippeite-type layers oriented parallel to (101). The empirical chemical formula calculated for a total of 70 O atoms is Cu 6.52 U 7.85 S 4.02 O 70 H 55.74 , leading to the simplified chemical formula Cu 6.5 [(UO 2 ) 4 O 4 (SO 4 ) 2 ] 2 (OH) 5 ·25H 2 O. The distance of 9.16 A between the uranyl-sulfate sheets in pseudojohannite shows that neighboring layers do not share O atoms with the same CuΦ 6 [Φ = (O,OH)] distorted octahedrons, such as in magnesium-zippeite. Rather, it is expected that CuΦ 6 forms a layer bound to the zippeite-type layers by hydrogen bonding, as in marecottite, or one apex of the CuΦ 6 polyhedron only is shared with a zippeite-type layer, as in synthetic SZIPPMg. The higher number of cations in the interlayer of pseudojohannite (Cu:S = 1.6:1) compared to marecottite (3:4) and SZIPPMg (1:1) indicates that pseudojohannite has a unique interlayer topology. Ab-initio powder structure solution techniques can be used to obtain important structural information on complex micro-crystalline minerals such as those found in the weathering environment. Pseudojohannite represents a new member of the zippeite group of minerals, and further illustrates the structural complexity of zippeite-group minerals containing divalent cations, which have diverse arrangements in the interlayer. Peudojohannite and other divalent zippeites are common, easily overlooked minerals in acid drainage environments around uranium deposits and wastes.

89Sr production in a reactor with solution fuel

The experimental results for the validation of a technology for producing 89Sr in a reactor with solution fuel are presented. The aggregate state of the fuel-a water solution of uranyl sulfate UO2SO4-opens up a unique possibility of acting not only on the target radionuclide but also on its genetic precursors, produced as a result of nuclear transformations of the fission products as a whole in the decay chain 89Se→89Br→ 89Kr→89Rb→89Sr. The half-life of 89Kr (T1/2 = 190 sec)-a gaseous precursor of 89Sr-is sufficient for it to leave the fuel solution and migrate into the gaseous medium.

Crystal structure and nonlinear optical properties of the K2UO2(SO4)2 · 2H2O compound at 293 K

Single crystals of potassium uranyl sulfate are grown, and their atomic structure is determined using X-ray diffraction analysis. The compound crystallizes in the orthorhombic crystal system with space group Pna2{sub 1} [a = 13.773(4) A, b = 7.288(2) A, c = 11.556(4) A, R{sub 1} = 0.033, wR{sub 2} = 0.0892 for 2630 reflections with I > 2{sigma}(I)]. The crystal structure of the K{sub 2}UO{sub 2}(SO{sub 4}){sub 2} . 2H{sub 2}O compound is built up of two-dimensional infinite, negatively charged layers of the composition [UO{sub 2}(SO{sub 4}){sub 2}.H{sub 2}O]{sub 2{infinity}}{sup {delta}}{sup -}], which are linked together through the K{sup +} ions. The specific features of the atomic arrangement in the structure of this compound are analyzed, and the second harmonic generation of laser radiation is investigated.

The Application of near Infrared Spectroscopy for the Detection of Secondary Uranium Minerals Using a Fibre-Optic Probe

The proposed increase in usage of nuclear power implies increased nuclear waste resulting in the formation of many uranyl secondary minerals. These minerals can translocate and a method of easy identification is required. Because many of the minerals contain water and/or OH units, the minerals lend themselves to near infrared spectroscopy. Spectra of a range of uranyl carbonate, sulphate and silicate minerals were obtained using a fibre optic-probe with an attenuated total reflectance cell in reflectance mode. The minerals include andersonite, liebigite, rutherfordine, uranopilite, zippeite, boltwoodite, soddyite, sklodowskite, uranophane and weeksite. These uranyl minerals are characterised by intense bands around 7000 cm−1 resulting from the second harmonic of the normal mode of the OH groups. Uranyl silicates show intense bands in the 4200 to 5400 cm−1 region. Two sets of bands, which are electronic in nature, are observed: one centred upon 10100 cm−1 and a second set around 8500 cm−1 in the high wavenumber region.

Crystal structure of CoUO2(SO4)2 · 5H2O at 293 K

Single crystals of cobalt uranyl sulfate are grown. The crystal structure is established by X-ray diffraction: the orthorhombic system, sp. gr. Pmc21, a = 6.452(2) A, b = 8.295(2) A, c = 11.288(3) A, R1 = 0.0303, wR2 = 0.0735 for reflections with I > 2σ(I). The structure of CoUO2(SO4)2 · 5H2O consists of infinite two-dimensional uncharged [CoUO2(SO4)2H2O]2∞ layers, which are linked to each other by hydrogen bonds.

Structures and syntheses of four Np 5+ sulfate chain structures: Divergence from U 6+ crystal chemistry

Four Np 5+ sulfates, X 4[(NpO 2)(SO 4) 2]Cl ( X=K, Rb) ( KS1 , RbS1), Na 3[(NpO 2)(SO 4) 2](H 2O) 2.5 ( NaS1), and CaZn 2[(NpO 2) 2(SO 4) 4](H 2O) 10 ( CaZnS1) were synthesized by evaporation of solutions derived from hydrothermal treatment. Their structures were solved by direct methods and refined on the basis of F 2 for all unique data collected with Mo Kα radiation and a CCD-based detector to agreement indices ( KS1, RbS1 , NaS1, CaZnS1) R 1 = 0.0237 , 0.0593, 0.0363, 0.0265 calculated for 2617, 2944, 2635, 2572 unique observed reflections, respectively. KS1 crystallizes in space group P2 /n, a = 10.0873 ( 4 ) , b = 4.5354 ( 2 ) , c = 14.3518 ( 6 ) , β = 103.383 ( 1 ) ° , V = 638.76 ( 5 ) Å 3 , Z = 2 . RbS1 is also monoclinic, P2/ n, with a = 10.5375 ( 8 ) , b = 4.6151 ( 3 ) , c = 16.0680 ( 12 ) , β = 103.184 ( 1 ) ° , V = 699.33 ( 9 ) Å 3 , Z = 2 . NaS1 is monoclinic, P2 1 /m, with a = 7.6615 ( 5 ) , b = 7.0184 ( 4 ) , c = 11.0070 ( 7 ) , β = 90.787 ( 1 ) ° , V = 591.81 ( 6 ) Å 3 , Z = 4 . CaZnS1 is monoclinic, P2 1 /m, with a = 8.321 ( 2 ) , b = 7.0520 ( 2 ) , c = 10.743 ( 3 ) , β = 91.758 ( 5 ) ° , V = 630.1 ( 3 ) Å 3 , Z = 2 . The structures of KS1 and RbS1 contain chains of edge-sharing neptunyl hexagonal bipyramids, with sulfate tetrahedra attached to either side of the chain by sharing edges with the bipyramids. NaS1 and CaZnS1 both contain chains of neptunyl pentagonal bipyramids and sulfate tetrahedra in which each bipyramid is linked to four tetrahedra, three by sharing vertices and one by sharing an edge. Bipyramids are bridged by sharing vertices with sulfate tetrahedra. Each of these structures exhibits significant departures from those of uranyl sulfates.

Molecular structure of the uranyl mineral zippeite - An XRD, SEM and Raman spectroscopic study

Raman spectra at 298 and 77 K and infrared spectra of the uranyl sulfate mineral zippeite, K2[(UO2)6(SO4)3O(OH)6]. 4 H2O, were studied. Observed bands were tentatively attributed to the (UO2)2+ and (SO4)2- stretching and bending vibrations, the OH stretching vibrations of water molecules and hydroxyls, H2O bending vibrations and libration modes, and ￤ U-OH bending vibrations. Empirical relations were used for calculation of U-O bond lengths in uranyl R = f(￮3 or ￮1 (UO2)2+) A. This was found in agreement with U-O bond lengths from the single crystal structure analysis. The number of observed bands supports the conclusion from single crystal structure analysis that at least two symmetrically distinct U6+ (in uranyl) and S6+ (in sulfate), and water molecules and hydroxyls may be present in the zippeite crystal structure. Some O-H…O bond lengths were attributed to the hydrogen-bonding network in zippeite crystal structure.

Comparative study of the flexibility of structural complexes in uranyl sulfates, chromates, and molybdates

Comparative study of the flexibility of structural complexes in uranyl sulfates, chromates, and molybdates involves statistical analysis of the U-Obr-T bond angles and T-O bond lengths in TO4 tetrahedra. The analysis is based on the available high-precision (R1 < 0.06) crystal structure data. The mean bond lengths in the TO4 tetrahedra are 1.473(1), 1.647(3), and 1.762(2) A for T = S, Cr, and Mo, respectively. The T-Obr bonds with bridging oxygen atoms are, as a rule, longer than the T-Ot bonds with the terminal oxygen atoms. Analysis of the distribution of U-Obr-T bond angles suggests increased flexibility of the U-Obr-Mo units compared to the corresponding units in the sulfates and chromates, which is responsible for the greater structural diversity of uranyl molybdates, with formation of framework structures being possible. The mean angles 〈U-Obr-T〉 are within 141.1°–142.6°.

Structure of the UO22+—SO42‐ Ion Pair in Aqueous Solution.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Structure of the UO2 2+-SO 4 2- ion pair in aqueous solution.

The structure of the ion pairs formed in aqueous uranyl sulfate solutions has been investigated with high-energy X-ray scattering. Sulfate binds to the uranyl as a monodentate ligand in equimolar solutions. The geometry of the ion pair is very similar to configurations found in crystalline structures; in particular, the U-O-S angle is bent in solution as well as in the solid state. It can therefore be concluded that an U-O-S angle of 143 degrees is an intrinsic property of the uranyl sulfate bond and not due to packing effects or interaction with the water in the primary solvation shell.

Formation of Excited Uranyl Ion in Oxidation of U(IV) with Xenon Trioxide in Aqueous Solutions of H2SO4and HClO4: I. Influence of Sulfate Anions

Kinetic and chemiluminescent parameters of U(IV) oxidation with xenon trioxide in 1 M H2SO4 were studied in relation to complexation of U(IV) with SO42- anions. The rate constant of oxidation of the sulfate complexes increases from ∼1 to 43 l mol-1 s-1 with increasing [Na2SO4] in the solution from 10-3 to 3×10-1 M. The equilibrium concentrations of aqua- and mono- and bisulfate complexes of U(IV) were calculated at different [Na2SO4] in the solution. The rate constant of reaction of U(SO4)2 with XeO3 [k = 72 l mol-1 s-1] is higher by an order of magnitude than the rate constant of oxidation of U(IV) monosulfate complex [k = 6.5 l mol-1 s-1]. The dependence of the lifetime of excited uranyl ions (τ) on the Na2SO4 concentration in 1 M HClO4 was measured. The chemiluminescence (CL) yield increases in the presence of sulfate anions owing to the growth of both the emission output of excited uranyl sulfate complexes and the yield of excitation of the CL emitter.

Programs of Experiments with Critical Assemblies at the Russian Research Centre “Kurchatov Institute”

The paper gives a brief overview of benchmark experiments that have been performed and are being performed at the Russian Research Centre “Kurchatov Institutes” (RRC KIs), satisfy requirements of the International Criticality Safety Benchmark Evaluation Project (ICSBEP), and have been published or will be published in the “International Handbook of Evaluated Criticality Safety Benchmark Experiments.”These experiments include critical experiments in water-moderated facilities pertaining to substantiation of reactor physics for VVER-type light water reactors with uranium enrichments varying from natural uranium to ˜6.5%; in heterogeneous critical assemblies with a widely varying uranium enrichment (from 5 to 96%) for small nuclear power systems of various applications; in critical assemblies with a uranyl sulfate solution core; and in critical assemblies simulating peculiarities of high-temperature gas-cooled reactors (HTGR), RBMK physics, etc.A list of critical assemblies currently in operation at RRC KI is given. Future experimental programs are briefly described; their implementation, if based on the ICSBEP requirements, will be useful for the international community.Using RRC KI as an example, it is demonstrated that Russian nuclear centers maintain capabilities for carrying out a wide range of new critical experiments, including international cooperation in this area.

A new uranyl carbonate sheet in the crystal structure of fontanite, Ca[(UO2)3(CO3)2O2](H2O)6

The structure of fontanite, Ca[(UO 2 ) 3 (CO 3 ) 2 O 2 ](H 2 O) 6 , is monoclinic, space group P2 1 /n, a = 6.968(3), b = 17.276(7), c = 15.377(6) Å, β = 90.064(6)°, V = 1851(1) Å 3 , Z = 4. The structure was solved by direct methods and refined on the basis of F 2 for all unique reflections using leastsquares techniques to an agreement index (R1) of 9.9%. The structure contains two symmetrically distinct uranyl pentagonal bipyramids, one uranyl hexagonal bipyramid, and two CO 3 triangles. The uranyl polyhedra form chains by sharing equatorial edges, and CO 3 groups occur on either side of the chains, where they share equatorial edges of the uranyl hexagonal bipyramids. The CO 3 groups share their third ligand with a uranyl pentagonal bipyramid of an adjacent chain, resulting in uranyl carbonate sheets of composition [(UO 2 ) 3 (CO 3 ) 2 O 2 ] 2- . The single symmetrically unique Ca 2+ cation is located between the sheets, and is coordinated by two O atoms of uranyl ions of adjacent sheets, and six H 2 O groups. The uranyl carbonate sheet in fontanite is novel, but is based upon the phosphuranylite anion topology that is the basis of uranyl phosphate, uranyl selenite, and uranyl sulfate sheets in a variety of minerals.

Contribution to the mineralogy of acid drainage of Uranium minerals: Marecottite and the zippeite-group

Sulfate-rich acid waters produced by oxidation of sulfide minerals enhance U mobility around U ores and U-bearing radioactive waste. Upon evaporation, several secondary uranyl minerals, including many uranyl sulfates, precipitate from these waters. The zippeite-group of minerals is one of the most common and diverse in such settings. To decipher the nature and crystal chemistry of the zippeite-group, the crystal structure of a new natural hydrated Mg uranyl sulfate related to Mgzippeite was determined. The mineral is named marecottite after the type locality, the La Creusaz U prospect near Les Marécottes, Western Swiss Alps. Marecottite is triclinic, P1, with a = 10.815(4), b = 11.249(4), c = 13.851(6) Å, a = 66.224(7), b = 72.412(7), and g = 69.95(2)°. The ideal structural formula is Mg 3 (H 2 O) 18 [(UO 2 ) 4 O 3 (OH)(SO 4 ) 2 ] 2 (H 2 O) 10 . The crystal structure of marecottite contains uranyl sulfate sheets composed of chains of edge-sharing uranyl pentagonal bipyramids that are linked by vertex-sharing with sulfate tetrahedra. The uranyl sulfate sheets are topologically identical to those in zippeite, K(UO 2 ) 2 (SO 4 )O 2 ·2H 2 O. The zippeite-type sheets alternate with layers containing isolated Mg(H 2 O) 6 octahedra and uncoordinated H 2 O groups. The uranyl sulfate and Mg layers are linked by hydrogen bonding only. Magnesium-zippeite is redefined as Mg(H 2 O) 3.5 (UO 2 ) 2 (SO 4 )O 2 , based on comparison of the powder X-ray diffraction pattern of micro-crystalline co-type material with the pattern of a synthetic phase. Magnesium-zippeite contains zippeite-type uranyl sulfate sheets with Mg located between the layers, where it is in octahedral coordination. In Mg-zippeite, distorted Mg octahedra are linked by sharing vertices, resulting in dimers. The apices of the Mg octahedra correspond to two O atoms of uranyl ions, and four H 2 O groups. Magnesium-zippeite and marecottite co-exist, sometimes in the same sample, at Lucky Strike no. 2 mine, Emery County, Utah (type locality of Mg-zippeite), at Jáchymov, Czech Republic, and at La Creusaz. This study provides insight into the complexity of the zippeite-group minerals containing divalent cations, where different arrangements in the interlayers result in different unit cells and space groups.