Uranyl nitrate, aqueous solutions

In particular, when a solvent extraction system of uranyl nitrate, aqueous nitric acid, and tri-n-butyl phosphate (TBP) in a hydrocarbon diluent was irradiated with a CO2 laser, a change was observed in the equilibrium distribution of uranyl nitrate between the phases (14). When the solution was irradiated at 944 cm 1, close to the uranyl asymmetric stretching frequency, the effect was observed. When a nonresonant frequency was used or the energy was absorbed in the solvent, no effect was observed. Little heating could be expected, and, in any case, heating effects should have been in the opposite direction from that observed. 

Homogeneous Aqueous Reactors. As a part of the research on neutron multiphcation at Los Alamos in the 1940s, a small low power reactor was built using a solution of uranium salt. Uranyl nitrate [36478-76-9] U02(N0 2> dissolved in ordinary water, resulted in a homogeneous reactor, having uniformly distributed fuel. This water boiler reactor was spherical. The 235u... 

Inorganic extractions seem to have come into practical use without any great notice. Although Peligot in 1842 reported that uranyl nitrate could be recrystalhzed from ether, he never mentioned extraction of this salt from aqueous solutions. In textbooks after 1870, however, it is stated briefly that ether can even withdraw sublimate (HgCy from aqueous solution. It was also reported, for example, that cobalt thiocyanate is weakly extracted by ether, better by amyl alcohol, and even better by a mixture of both. 

The extraction of uranyl nitrate from 1 M aqueous solution into 30% tributylphosphate in oil is accompanied by an initial interfacial turbulence (41), with more transfer than calculated, even though re-solvation of each uranyl ion at the interface must be a relatively complex process. If the turbulence is suppressed with sorbitan mono-oleate, transfer proceeds at a rate in excellent agreement with theory. 

Solubility in Aqueous Solutions of Ammonium Sulfate, Ammonium Acid Sulfate, Sodium Chloride, Sodium Nitrate, Lead Nitrate, Uranyl Nitrate and Ammonium Thiocyanate... 

Stoichiometrical quantities of the HDBM (l,3-diphenyl-l,3-pentanedione) and U02 (CH3COO)2 were dissolved in tepid ethanol. The solution was concentrated and left at room temperature until crystallization. The product was washed with ether and dried at 130°C and a pressure of I0 7 mm Hg in an Abderhalden drying apparatus provided with P4O]0. Uranyl bis-(2-hydroxybenzaldehyde) [79] was synthesized from stoichiometric quantities of an alcoholic solution of 2-hydroxybenzaldehyde and an aqueous solution of uranyl nitrate trihydrate, U02(N03)2 3H20. It is noted [79] that, for uranyl P-diketonates his-(2-hydroxybenzaldehyde) and b is-(2 - h ydroxy-1 -naphtli a I d e h y de), their crystals do not exhibit the appropriate size and crystalline shape to perform polarization measurement in the solid state. 

Solvent Extraction. The yellow cake is dissolved in nitric acid and extracted from this aqueous phase by 5 percent tributyl phosphate (TBP) in a hydrocarbon diluent. The diluent reduces the density and viscosity of the TBP, enhancing the aqueous/solvent phase separation. The extraction is very specific for uranium, with separation factors of 103 to 105. The product thus obtained is an aqueous uranyl nitrate solution (Fig. 21.14). 

Hexavalent. Nitrate complexation with actinide ions is very weak, and the determination of the formation constants for aqueous nitrate solution species is extremely difficult. Under aqueous conditions with high nitric acid concentrations, complexes of the form An02(N03)(H20)x+, An02(N03)2(H20)2, and An02(N03)3 (An = U, Np, Pu) are likely to be present. Solids of the anionic trisnitrato complex have been isolated for U and Np however, minimal structural data have been obtained. Solid uranyl nitrate, U02(N03)2-xH20, is obtained as the orthorhombic hexahydrate from dilute nitric acid solutions and as the trihydrate from concentrated acid. The Np analog can be precipitated from a mixed aqneons HNO3 and MeCN solntion by the addition of 18-crown-6. Multiple structural determinations have been made for the hexavalent uranium nitrate complexes, and all show the common formula unit of... 

Uranyl Iodide, UOglj, is prepared by adding barium iodide in slight excess to an ethereal solution of uranyl nitrate. It separates in red crystals which are deliquescent and unstable, losing iodine in the air, and in aqueous solution forming hydriodic acid and free iodine. ... 

A solution of uranyl nitrate was used for the extraction of aluminum and chromium from acetate-buffered aqueous media with trifluoracetylacetone in benzene. 

U is then heated to 50-65 C, which assists the back extraction, and contacted with demineralized water to give a pure aqueous uranyl nitrate product stream and a barren solvent phase for recycle. The product solution might contain ca. 100 g dm while the aqueous raffinate from the first extraction may contain ca. 0.1 g dm The concentrations of boron and cadmium in the solid U02(N03)2 6H20 product obtained by evaporation of and crystallization from the product solution will be 0.2 p.p.m. or less. 

The U02 - XOs - H2O (X= C or N) systems have been chosen for analysis for two reasons. First, they are well studied experimentally, since carbonate and nitrate uranyl complexes are important from technological standpoints. Second, the isoelectronic anions XOs have the same planar structure (symmetry Dsh) and form bidentate coordination around uranyl ions (the type). However, their electron-donor characteristics are different El = 3.1 and 3.4 for the NOs and COs ions, respectively. From this viewpoint, it would be of interest to understand how the difference in the electron-donor properties influences complex formation in the U02 - XOs " - H2O systems. As in the case of aqua-complexes, we shall use the 18-electron rule to obtain answers to the following questions (a) what is the composition of stable complexes in aqueous solutions containing carbonate or nitrate uranyl complexes (b) what is the coordination number of U(VI) in these complexes. 

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