Uranous nitrate

Uranous Nitrate has not been obtained in the solid form. It appears to exist in the unstable green solution obtained on the addition of uranous hydroxide to a neutral solution of silver nitrate (see p. 302). A light green basic nitrate has been obtained by short exposure to light of an eoholic solution of uranyl nitrate, and rapid filtration of the product. ... 

Uranium Z, also thought to be a product of uranium X, was discovered by Hahn in 1921, who isolated it in the following manner. The mother-liquors from repeated fractional crj stallisations of uranous nitrate, containing uranium X and uranium Z, w ere treated with ferric chloride solution, and the iron precipitated by means of ammonia and ammonium carbonate. The precipitate, which contained both the uranium Xj and uranium Z, was treated with a solution of tantalum in hydrofluoric acid, lanthanum nitrate added, and the mixture digested on a water-bath with dilute hydrofluoric and sulphuric acids. Lanthanum fluoride was precipitated, and carried do%vn with it uranium The filtrate was evaporated to dryness and the residue ignited. The tantalum was thus rendered insoluble, whilst the iron could be removed by means of concentrated hydrochloric acid. The uranium Z remained with the tantalum. By this means Hahn obtained specimens of uranium Z which were 99-5 per cent, radioactively pure. 

Uranous nitrate [U(N03)4] solution is used for the quantitative reduction of plutonium from loaded tributyl phosphate (TBP) phase [8]. Membrane cell technology was investigated for the production of 100% uranous nitrate solution [9], which is to be used in the partition cycle of the PUREX process in the fuel reprocessing plant. The membranes used hitherto have suffered from mechanical instability. A study was carried out at the BARC to obtain 100% uranous nitrate solution using a membrane-based electrolytic cell. The membrane used in this study was a thin polymer film reinforced with a Teflon fabric. The film was used as a separator between the anolyte and catholyte chambers, which are made of perfluorinated polymers, thus offering high thermal and chemical stability. 

Singh, RK. et al. Role of Ion Transfer Membrane in the Production of Uranous Nitrate, BARC Report. BARC/1992/E/002. 

Pure uranous compounds may be prepared by precipitating U(OH)4 from aqueous solution with ammonium hydroxide and dissolving the precipitate in the appropriate acid. Uranous sulfate, the most common salt, is soluble in water, as are the chloride, bromide, and iodide. Uranous nitrate is unstable, gradually undergoing oxidation to uranyl nitrate with liberation of oxides of nitrogen. 

The particle size also tends to grow with increasing residence time in the bed, and this is particularly the case with uranyl nitrate concentrations above 70 per cent. This can be counteracted by recycling a proportion of the product continuously, after grinding. The finely ground particles act as nuclei for the deposition of further oxide and a satisfactory average particle size can be achieved. In practice, it is more convenient to employ a uranly nitrate concentration of about 70 per cent. 

Once plutonium and uranium are coextracted and codecontaminated, plutonium is separated from uranium in the partitioning contactor by reduction to Pu(III) with a reduc-tant. Over the years, a number of plutonium reductants have been proposed. The most widely used reductant to partition plutonium from uranium in the PUREX process was (Fe(S03NH2)2) other alternates were proposed such as hydrazine-stabilized ferrous nitrate or uranous nitrate, and hydroxylamine salts. 

Furthermore, uranous nitrate is being successfully used af the Rokkasho Mura reprocessing plant in Japan to separate uranium from plutonium. One of the advantages of U(IV) is that it does not introduce nonvolatile or corrosive constituents as compared with ferrous sulfamate or ferrous nitrate. 

Uran-metail, n. uranium metal, -nitrat, n. uranium nitrate. 

Uranous Salt. — The solution of 1 gm. of uranium nitrate in 20 cc. of water and 1 cc. of dilute sulphuric acid should be colored red on the addition of 0.1 to 0.2 cc. of decinormal potassium permanganate. 

Reactions in Molten Salt Solutions. I. Uranate and Neptunate Formation in Molten Lithium Nitrate-Sodium Nitrate, W.T. Camall, S.J. Neufeldt, and A. Walker, Inorg. Chem. 4, 1808-1813 (1965). 

The main oxides are U02, which is brown-black and highly non-stoichiometric, U308, greenish-black, and U03 orange yellow. The latter is best made by heating uranyl nitrate or ammonium uranate (see below) and the other oxides can be made from U03 ... 

Uranium Molybdates.—Uranyl nioh bdate, UO2M0O4, is obtained as a white amorphous precipitate when ammonium molybdate is added to uranyl nitrate solution in the dark. It is reduced to uranous molybdate. U(Mo04)2, becoming green by the action of ethyl or methyl alcohol or acetic acid, and dissolves in mineral acids with a yellovush-... 

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. 

Uranous Hydroxide.—The addition of alkali to a solution of a uranous salt produces a reddish-brown gelatinous precipitate, which darkens in colour on boiling the solution. If dried in vacuo it becomes black and has the composition UOg.HgO. This rapidly oxidises in the air and readily dissolves in dilute acids, forming uranous salts. It acts upon a neutral solution of silver nitrate, first precipitating silver oxide and forming a green solution which, however, soon turns yellow, and the oxide is reduced to metallic silver as the uranyl salt forms in solution, thus ... 

Uranium Trioxide, Uranic Oxide, Uranic Anhydride, or Uranyl Oxide, UO3, is obtained when uranic acid, ammonium diuranate, or ammonium uranyl carbonate is heated to a temperature not exceeding 300° Cd When uranyl nitrate is similarly heated the product always contains basic nitrate, but if this product is heated in a current of oxygen at 500° C. it yields pure uranium trioxide. ... 

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