Uranium peroxide

Actinide Peroxides. Many peroxo compounds of thorium, protactinium, uranium, neptunium, plutonium, and americium are known (82,89). The crystal stmctures of a number of these have been deterrnined. Perhaps the best known are uranium peroxide dihydrate [1344-60-1/, UO 2H20, and, the uranium peroxide tetrahydrate [15737-4-5] UO 4H2O, which are formed when hydrogen peroxide is added to an acid solution of a uranyl salt. 

Uranium Peroxide Hydrate. Add a 3% hydrogen peroxide solution dropwise to 5 ml of a 10% uranyl nitrate solution up to complete precipitation. Filter off the product on a small filter, wash it with water, and dry it in a drying cabinet at 70 °C. What is the composition of the product Test the reaction of uranium peroxide hydrate with 10% solutions of acids and alkalies in the cold and when heated. 

Uranium Oxides. Weigh 0.5 g of uranium peroxide hydrate in a crucible and heat it in a crucible furnace with constant stirring. 

Actinide Peroxides. Many peroxo compounds of thorium, protactinium, uranium, neptunium, plutonium, and americium are known. Uranium peroxide has found several applications in the nuclear energy industry . 

Hydrogen peroxide pale-yellow precipitate of uranium tetroxide U04.2H20 (sometimes called uranium peroxide), soluble in ammonium carbonate solution with the formation of a deep-yellow solution. Chromium, titanium, and vanadium interfere with this otherwise sensitive test. 

No dermal effects were seen following application of a single dose of 618 mg U/kg as uranyl fluoride, 666 mg U/kg as uranium trioxide, 195 mg U/kg as sodium diuranate, 198 mg U/kg as ammonium diuranate, 410 mg U/kg as uranium peroxide, 458 mg U/kg as uranium dioxide, or 147 mg U/kg as triuranium octaoxide in 50% aqueous solution to the shaved skin of New Zealand white rabbits (Orcutt 1949). No dermal effects were observed on the shaved backs of New Zealand white rabbits to which a single dose of 98 mg U/kg as a 65% concentration of the uranium tetrafluoride in lanolin was applied (Orcutt 1949). Similarly, application of 3,929 mg U/kg as uranyl acetate dihydrate or 2,103 mg U/kg as ammonium uranyl tricarbonate in water-Vasehne emulsion to a 3 cm shaved area of the uncovered backs of 20 male Wistar rats in 1-10 daily applications had no effect on the skin of the rats (De Rey et al. 1983). 

Evidence also suggests that the toxicity of uranium varies according to the route of exposure and to its compounds. This finding may be partly attributable to the relatively low gastrointestinal absorption of uranium compounds. Only <0.1-6% of even the more soluble uranium compounds are absorbed in the gastrointestinal tract. On the basis of the toxicity of different uranium salts in animals, it was concluded that the relatively more water-soluble salts (uranyl nitrate hexahydrate, uranyl fluoride, uranium pentachloride) were primarily renal and systemic toxicants. The less water-soluble compounds (uranium trioxide, sodium diuranate, ammonium diuranate) were of moderate-to-low toxicity, while the insoluble compounds (uranium tetrafluoride, uranium dioxide, uranium peroxide, triuranium octaoxide) were... 

The two chief oxides of uranium are the basic uranous oxide UO2 and the acid anhydride UO3. Intermediate between these two is a well-defined green oxide of composition UgOg. Less certain is the existence of a pentoxide UgOj, and a tetroxide, uranium peroxide, UO, though well-defined derivatives of the latter, peruranates, are known. 

Uranium peroxide U04 2H2 0 is prepared by precipitation of an aqueous solution of uranyl nitrate at 70 to 80°C and a pH of 3 to 4 with H2O2. Because few other cations form precipitates under these conditions, this is an effective way of purifying uranium. 

For the other actinide elements the usual starting material will be the dioxide. Although these reactions appear to be simple, they are in fact quite complex. Uranium trioxide as prepared by thermal decomposition of uranyl nitrate hexahydrate, uranium peroxide, or ammonium diuranate may exist in any one of at least four crystal modifications and in an important amorphous form. The reduction of U03 appears to be related both to the crystal form and to the surface area, and depending on these and perhaps other still unspecified variables, the hydrofluorination reaction on the... 

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