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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 bipyramidalmore » 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 mineralizing agent and a ligand.« less

Single crystals of barium iodate were grown by simple gel technique by single diffusion method. By varying various parameters, optimum conditions for the growth were established. Crystals having different morphologies and habits were obtained. Prismatic, prismatic pyramidal, dendritic crystals were obtained. Some of them were transparent, some were transluscent, and few others were opaque. The crystals were doped by impurities such as Fe 3+ and Cu 2+ . The formation of the compound was verified by X-ray diffractograms. The results were compared with the standard values given in JCPDS file. It confirms that the grown crystals are barium iodate, monohydrate. Structural analysis was carried out using FT-IR technique. It confirms the iodate group of the grown crystals. Nonlinear optical properties were studied by using powder second harmonic generation method. Effect of doping of Fe 3+ and Cu 2+ on the structure and nonlinear optical properties of bulk crystals was studied. Doping has no effect on the structure. Doping of Cu +2 inhibits nonlinear behavior of the substance, while Fe +3 doping of has less negative effect.

Single crystals of calcium iodate and barium iodate were grown by simple gel technique by single diffusion method. The optimum conditions were established by varying various parameters such as pH of gel solution, gel concentration, gel setting time, concentration of the reactants etc. Crystals having different morphologies and habits were obtained. Prismatic, dendritic crystals of barium iodate and prismatic, needle shaped, hopper crystals of calcium iodate were obtained. Some of them were transparent, some transluscent, and few others were opaque. Both the crystals were studied using XRD, FT-IR, and thermal analysis. The crystals were doped by iron impurity. The effect of doping was studied using IR spectroscopy and thermal analysis.

The solubility of Ba(IO(3))(2) has been determined in solutions containing a supporting electrolyte (KCl) to maintain the ionic strength in the 0-0.5 M range. The approach envisaged was based in the amperometric determination of iodine (or triiodide) generated in the reaction involving iodate in equilibrium in the saturated solutions and iodide contained in the solution carrier using a flow injection procedure, the electrode potential being maintained at +0.2 V in a wall-jet cell. The effect of the supporting electrolyte on the solubility of barium iodate was demonstrated and a good approximation of the value for the thermodynamic solubility constant of the precipitate was found by an appropriate correction of the solubility data using mean activity coefficients of barium iodate. The mean activity coefficients were estimated at each ionic strength by using the Debye-Hückel equation and the corrected solubility constant determined at 27 degrees C was found to be 2.7x10(-9) mol(3) l(-3).

A set of reactive chemical transport calculations was conducted with the Subsurface Transport Over Reactive Multiphases (STORM) code to evaluate the long-term performance of a representative low-activity waste glass in a shallow subsurface disposal system located on the Hanford Site. Two-dimensional simulations were run until the waste form release rates reached a quasi-stationary-state, usually after 2,000 to 4,000 yr. The primary difference between the waste form release simulations for the 2001 ILAW PA, and the simulations described herein, is the number of different materials considered. Whereas the previous PA considered only LAWABP1 glass, the current PA also describes radionuclide release from three different WTP glasses (LAWA44, LAWB45 and LAWC22), two different bulk vitrification glasses (6-tank composite and S-109), and three different grout waste forms (containing Silver Iodide, Barium Iodide and Barium Iodate). All WTP and bulk vitrification glasses perform well. However, the radionuclide release from the salt in the cast refractory surrounding the bulk vitrification waste packages is 2 to 170 times higher than the glass release rate, depending on the water recharge rate. Iodine-129 release from grouted waste forms is highly sensitive to the solubility of the iodine compound contained in the grout. The normalized iodine release rate from grout containing barium iodate is a factor of 10 higher than what the normalized release rate would be if the iodine were contained in LAWA44 glass.

Single crystals of iodates of barium and strontium grown by gel method are reported. Optimum conditions for good quality single crystals are worked out. Different habits of these crystals are reported. A brief report for characterization of these crystals by different methods is given.

The dimesoperiodates of the alkaline earths, M 2 I 2 O 9 . n H 2 O (Ca, n = 8; Sr and Ba, n = 3) on thermolysis form hexavalent iodates, MIO 4 as intermediate products which with increasing temperature decompose to their orthoperiodates, M 5 (10 6 ) 2 via presumably the formation of M 2 I 2 O 7 type compounds. MIO 4 compounds can be made from dimesoperiodates by heating at 220–240° for 2 hr. The hexavalent state of iodine in MIO 4 has been verified by chemical analysis, magnetic moment measurement and EPR spectra. These compounds undergo hydrolytic decomposition to metal iodate and hydroxide accompanied by the evolution of oxygen. Anhydrous barium iodate prior to its decomposition undergoes a phase transition, this change is less defined in the strontium compound and is not observed in calcium iodate. The energy of activation, the order of reaction and the enthalpy change for the conversion of the iodates to the orthoperiodates have been evaluated by non-isothermal kinetic study.

Three polarographic micro-methods are described for the determination of sulphur in organic compounds after oxygen-flask combustion. The products are converted into sulphuric acid by oxidation with hydrogen peroxide, the excess of which is expelled through boiling. The methods are based upon allowing the sulphuric acid to react with an excess of barium iodate or bromate, then recording polarographically the cathodic reduction wave of the iodate or bromate ion. The bromate methods are superior to the iodate method being simpler and more rapid, and the results are correct to within ca. ±0.5%.

Der thermische Zerfall der Bariumperjodate Ba(JO4)2·4 H2O, Ba2J2O9·9 H2O, Ba3(JO5)2·9 H2O und des Bariumjodats Ba(JO3)2·2 H2O wurde zwischen 20−700°C untersucht. Eines der Produkte der thermischen Zersetzung von Ba2J2O9·9 H2O ist BaJO4·H2O mit formal sechswertigem Jod. Die magnetischen Suszeptibilitaten wurden gemessen; alle Jodate und Perjodate sind diamagnetisch, wahrend BaJO4·H2O paramagnetisch ist. Es liegt also eine definierte Verbindung vor. The course of the thermal decomposition of the barium periodates Ba(JO4)2 · 4 H2O, Ba2J2O9 · 9 H2O, Ba3(JO5)2 · 9 H2O and of barium iodate, Ba(JO3)2 · 2 H2O, has been studied in the range of 20 to 700°C. One of the products of the thermal decomposition of the periodate Ba2J2O9 · 9 H2O is a substance which contains a formally hexavalent iodine atom, of the composition BaJO4 · H2O. The magnetic susceptibility values of all decomposition products as well as of the initial substances have been determined. All thc iodates and periodates are diamagnetic, only the product BaJO4 · H2O is paramagnetic, which is proof of the fact that this is a real compound of hexavalent iodine.

The rates of dissolution and growth of barium iodate crystals in contact with aqueous solutions show variations which can be interpreted in terms of a surface process and diffusion between the surface and bulk solution. The former may be treated in terms of a theory previously proposed.

A bench-scale model of a mercuric nitrate scrubber for removal of iodine from off-gas streams was constructed and operated in conjunction with a mercuric iodate-to-barium iodate conversion system to determine the feasibility of total recycle of all processing solutions. The two main aspects of the system examined were (1) the extent of contamination of the barium iodate product, and (2) the effect of cross-contamination of various process solutions on the efficiency of the process. The experimental evidence obtained indicates that, with appropriate control, all solutions can be recycled without significant contamination of the product that would be harmful to the host concrete or to the environment. Mercury contamination was found to be less than or equal to 0.5 wt % of the barium iodate product. The most significant effect on system efficiency was determined to be barium hydroxide contamination of the sodium hydroxide solution used to convert mercuric iodate to sodium iodate. A mole ratio of barium hydroxide to sodium hydroxide of about 1:225 caused a decrease in conversion efficiency of about 45%.

One of the problems to be solved in the nuclear waste management field is the disposal of radioactive iodine-129 (1). This nuclide is one of the more volatile and long-lived fission products. Studies at ORNL have shown that fission products can be fixed in concrete for permanent disposal (2,3). Current studies have demonstrated that practical cementitious grouts may contain up to 18% iodine as barium iodate. The waste disposal criterion is based on the fact that harmful effects to present or future generations can be avoided by isolation and/or dilution. Long-term isolation is effective in deep, dry repositories; however, since penetration by water is possible, although unlikely, release was calculated based on leach rates into water. Further considerations have indicated that sea disposal on or in the ocean floor may be a more acceptable alternative.

The phase transitions, thermal stabilities and crystal structures of strontium iodate, barium iodate, calcium iodate, zinc iodate and cadmium iodate have been investigated by means of X-ray powder diffraction and thermal analyses. The possibilities of formation of complex compound between divalent iodates have been studied. The stability of hydrated divalent iodates is expected to be related to the electronegativity of the corresponding cations.

Crystal data of barium iodate monohydrate single crystals obtained with oscillation and Weissenberg photographs are reported. Crystals are grown by gel technique. Ba(IO3)2.H2O is orthorhombic with space group Fdd2. The lattice parameters with four formula units per cell are a = 7.96 (2), b = 9.01 (3) and c = 9.78 (5) A.

The solubilities of barium iodate containing I/sup 131/, europium iodate containing Eu(/sup 152+154)/, and hexamnainecobalt iodate containing Co/sup 60/ in salt solutions of ion-pairing ligands were measured by relating the count rates to the solubilities in H/sub 2/O at 25 deg C as found by volumetric estimation of the iodate concentrations. The results, combined with Davies's general activity coefficient expression, were used to calculate the corresponding dissociation constants. It was also demonstrated that such calculations may be made with only rough estimates of the solubilities in H/sub 2/O combined with the relative count rates of the aqueous salt solutions. (auth)

Between 2 and 100 µmoles of sulphate (60 to 3200 µg of sulphur) can be determined in aqueous solution, by passing the solution through a column of iodine-131 labelled barium iodate and counting the filtrate. The blank can be reduced by using 20 per cent. methanol. Each determination takes only a few minutes, and the precision is ±2·5 per cent. The apparatus required is simple and inexpensive, apart from the counting equipment. The method has been tested with standard kale, and has been applied to the determination of sulphur in fruticose lichens.