Uranyl nitrate preparation

EPA. 1983c. U.S. Enviromnental Protection Agency. Reportable quantity document for uranyl nitrate. Prepared by the Office of Health and Environmental Assessment, Cincinnati, OH, for the Office of Solid Waste and Emergency Response, Washington, DC. 

Another preparative method involves converting triuranium octaoxide to uranyl nitrate, U02(N0s)2, by treatment with nitric acid. Uranyl nitrate then is decomposed to uranium trioxide, UO3, which is reduced to the dioxide, UO2, with hydrogen. A fluidized bed of uranium dioxide is treated with hydrogen fluoride to produce uranium tetrafluoride, UF4, which then is treated with fluorine to form hexafluoride. The preparation should be done in copper apparatus. 

Uranyl nitrate is used to prepare several uranium salts. Also it is used to make uranium glaze and decorative porcelain, and as an intensifier in photography. It is an analytical reagent (e.g., Redox titration). 

Uranyl nitrate is obtained as an intermediate in recovering uranium from its minerals. The compound can be prepared by reacting triuranium octaoxide, UsOs, with nitric acid. It is separated and purified by extraction with ether. 

Diammino-uranyl Nitrate, [U02(NH3)2](N03)2, is formed when dry gaseous ammonia is passed into a boiling solution of dry uranyl nitrate in amyl alcohol until the liquid is decolorised. A voluminous yellow precipitate is formed, which is collected and dried in vacuo over sulphuric acid. The product is only freed from amyl alcohol by repeated evacuation over fresh quantities of sulphuric acid. It is a yellow amorphous powder, which is insoluble in ether and amyl alcohol. If the diammine is prepared in ether the same reaction takes place, and, after evacuation over sulphuric acid, a bright yellow powder is obtained of composition [UO2(NH3)2](NO3)2.C2H10O this, on keeping in vacuo, gradually loses ether, yielding the diammino-nitrate. 

Polymer and copolymer. Polymer and copolymer were prepared in our laboratory for strict control of purity, branching content and molecular weight. All monomers and solvents were carefully purified. PVC samples were prepared as powders in bulk using free radical photoinitiation with either AIBN or uranyl nitrate as initiators. The AIBN/UV initiation was used for photopolymerization at temperatures of 50°, 25°, and 0°C. 

Copolymers of vinyl chloride-vinyl bromide were prepared in bulk using the same conditions in the preparation of PVC, except that only uranyl nitrate was used as in initiator with visible light to avoid photodegradation during polymerization. Thermal analysis of the copolymer indicated random placement of the two comonomers. 

Two types of initiator were used in this work, AIBN and uranyl nitrate. Unreacted initiator was thoroughly removed from the polymer. A comparison of PVC samples prepared by the two different initiators showed identical behavior under ESR investigation. Therefore, end groups derived from the initiator do not appear to affect the course of degradation appreciably. 

Macroporous anion-exchange resin, useful for the sorption of uranyl nitrate, has been prepared by suspension polymerization of 4-methyl-2-vinylpyridine with trimethylene glycol dimethacrylate... 

Lin, R.H., Fu, W.M., Lin-Shiau, S.Y. (1988). Presynaptic action of uranyl nitrate on the phrenic nerve-diaphragm preparation of the mouse. Neuropharmacology 27 857-63. 

Two studies by MacDonald-Taylor et al. (1992, 1997) produced similar renal lesions in rabbits. In these studies, weanling New Zealand male rabbits were exposed to uranium for 91 days via drinking water containing 0, 24, or 600 mg/L uranyl nitrate Doses were not calculated from water intake. Calculations using default reference values for this species result in doses of 0, 0.93, and 23 mg U/kg/day (EPA 1998). Each treatment group was divided into 3 subgroups immediate sacrifice and either 45-day or 91-day recovery period. At the end of the recovery periods, rabbits were sacrificed and renal sections prepared... 

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. ... 

Uranous oxide is only difficultly soluble in hydrochloric and sulphuric acids, even when concentrated. With the latter acid, insoluble uranium sulphate is formed. It readily dissolves, however, in dilute nitric acid forming uranyl nitrate it is also soluble in aqua regia. The amounts of the oxide dissohdng in these acids in a given time vary widely with the mode of preparation of the oxide. 

Uranyl Nitrate, U02(N03)2.6H20, is the most important compound of uranium it has received much attention from investigators and is the most widely used uranyl salt of commerce. It is obtained directly from uraninite (see p. 277), and the commercial preparation, which generally contains a small amount of impurity, especially alkali, may be purified by reerystallising several times from water. 

BthylenediaminoIlium uranyl nitrate, C2H4(NH2)2.2HK03.U02(N03)2. 2H2O, has been prepared, ... 

The mixed oxide (U,Pu)02 can be prepared by adding ammonia to a mixed nitrate solution of plutonium(IV) nitrate and uranyl nitrate. The precipitate, which consists of Pu(OH)4 and (NH4)2U207, is converted to (U,Pu)02 by heating in hydrogen at 500-800°C. Typical conditions for the preparation of PUO2 and PUO2-UO2 powder are listed in Table 2. ... 

Derivation (pure oxide) Powdered uranium ore is digested with hot nitric-sulfuric acid mixture and filtered to remove the insoluble portion. Sulfate is precipitated from the solution with barium carbonate, and uranyl nitrate is extracted with ether. After re-extraction into water, it is heated to drive off nitric acid, leaving uranium trioxide. The latter is reduced with hydrogen to the dioxide. Can be prepared from uranium hexafluoride by treating with ammonia and subsequent heating of the ammonium diuranate. It is also recovered from phosphoric acid. 

Uranium trioxide or uranic oxide, UOs, may be prepared in pure form by long continued heating of uranyl-ammonium carbonate at 300° or of ammonium uranate at 250° uranyl nitrate also yields UOs on ignition, but the product contains basic nitrates unless the heating is done thoroughly. The color of the oxide varies from orange to red, depending on the method... 

Uranyl sulfate, UO2SO4 3 H20, is prepared by the crystallization of a solution of uranyl hydroxide in dilute sulfuric acid or by heating uranyl nitrate with sulfuric acid. It forms yellow-green crystals, which under the microscope show a beautiful fluorescence. On exposure to air they loose water slowly, and at 115° a monohydrate is formed while at 175° the anhydrous salt is produced. Both acid salts and double alkali sulfates are formed. 

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