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Uranyl ions precipitation

Isonltroso-N-phenvl-3-methylpyrazolone. Uranyl nitrate or acetate forms a reddish-orange precipitate with a Vft solution of the reagent in a 50 alcoholic solution. Precipitation is quantitative with the addition of sodium acetate. Mercury (l) and (ll), copper (l) and (ll) and uranyl ions precipitate In acidic media (nitrate or sulfate). In acetate solutions,... [Pg.53]

The hydrolysis of the uranyl(VI) ion, UO " 2> has been studied extensively and begins at about pH 3. In solutions containing less than lO " M uranium, the first hydrolysis product is the monomeric U02(OH)", as confirmed using time-resolved laser induced fluorescence spectroscopy. At higher uranium concentrations, it is accepted that polymeric U(VI) species are predominant in solution, and the first hydrolysis product is then the dimer, (U02)2(0H) " 2 (154,170). Further hydrolysis products include the trimeric uranyl hydroxide complexes (U02)3(0H) " 4 and (1102)3(OH)(154). At higher pH, hydrous uranyl hydroxide precipitate is the stable species (171). In studying the sol-gel U02-ceramic fuel process, O nmr was used to observe the formation of a trimeric hydrolysis product, ((U02)3( -l3-0)(p.2-0H)3) which then condenses into polymeric layers of a gel based on the... [Pg.326]

The dioxouranium(VI), or uranyl, ion is peculiar in forming two 8-quinolinol derivatives. Only the red crystalline compound containing an added mol of 8-quinolinol can be prepared by direct precipitation. This material has been recommended for the accurate determination of uranium-(VI)1,3,6,7 because of its insolubility, constancy of composition, ease of drying, and large molecular weight. [Pg.102]

This solid-phase disappears at pH 7.5 and U species including carbonate is formed above pH 7. The dominant species in the pH range of 7-9 and above 9 are (U02)2C03(0H)3" and 1102(003)3, respectively. The aqueous phases of uranyl ion, uranyl hydroxyl carbonate and uranyl carbonate are formed as the pHs of solution increase. The solid-phase is uranyl hydroxide around pH 7. It is found the equilibrium model calculations that the dominant species at pHs 5.5 or below is uranyl ion although the CO2 conditions were varied. Uranium is precipitated as a hydroxide form of 3 H02(0H)2(s) at a neutral pH. The aqueous phase of uranium hydroxide, hydroxyl carbonate and carbonate are dominant species at a high pH. These species have anionic charge. [Pg.556]

Calculations of metal ion speciation from literature data support the conclusions reached in the europium and uranyl systems. Literature data for the carbonate, hydroxide, and phosphate complexes of europium and uranium were used (5-72), with correction from infinite dilution to 0.1 M ionic strength via the Davies equation where necessary. The calculated fraction of metal ion precipitated as EUPO4... [Pg.282]

When sodium carbonate is present in excess, the uranyl ion forms a soluble carbonate complex, whereas most metals separate as carbonates, basic carbonates, or hydroxides [62] — with the exception of V, Be, and Th, which remain partly in solution together with uranium. If the precipitate contains several metals, double precipitation is necessary. The amount of uranium retained by the precipitate does not exceed a few percent. When a carbonate fusion is used for decomposition of the sample, and the melt is leached with water, uranium passes into solution. [Pg.447]

While investigating the radiochemical properties of uranium, W. Crookes and Becquerel made an important discovery. Precipitating a carbonate salt from a solution containing uranyl ions, they discovered that while the uranium remained in the supernatant liquid in... [Pg.2]

The uranyl ion, (U02), forms yellow azido complexes that are stable in dilute (0.01 M) aqueous solutions in the presence of excess azide a cation structure [(U02)(N3)] has been established and was used in the analysis of uranium [137,138]. The anion tetraazido complex has been isolated as the tetraphenylarsonium salt, [As(Ph)4]2 [(U02)(N3)4], by admixing a solution of 1 g uranyl nitrate in 2 N nitric acid in nitrogen environment to a solution of 7 g sodium azide. At 80°C the red solution was precipitated with tetraphenylarsonium chloride to obtain yellow crystallites that decomposed at 171°C [139]. [Pg.42]


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Uranyl

Uranyl ions

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