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Uranyl electrodes

Organophosphoric acids and a variety of organophosphorus mediators have been examined as liquid ion-exchanger systems for PVC uranyl ISEs (63,64) (Table 3.17). The sensors are readily made by multiple-stage extractions from [Pg.106]

Sensor Mediator Slope (mV decade ) Selectivity coefficients, /cyo. e (separate solution method)  [Pg.107]

After removing chloroform, the residual uranyl salt is incorporated with mediator into PVC membranes. This simple technique has proved useful for preparing other sensor material, e.g. zinc and beryllium organophosphates. [Pg.108]

The quest for improved uranyl sensors has rested with ionophores. lonophores suitable for calcium (5) and lithium (28) are subject to sodium and calcium interferences (Table 3.17) whereas amongst newer ones, (34) particularly is considered to provide a UOj device of unrivalled specificity (65). [Pg.108]

The hydrolysis of uranyl salts leads to four other uranium species, e.g., U02Cr, U020H-, U020H and (U02)2(OH)i-. From the standpoint of calibration, this problem is very readily accommodated by setting the pH of all standards at 3 so as to largely maintain the uranium (VI) as the primary species. The Nernstian slopes of this PVC-uranyl ISE in pH [Pg.108]


Partial regeneration of the product of the electrode reaction by a disproportionation reaction is characteristic for the reduction of the uranyl ion in acid medium, which, according to D. H. M. Kern and E. F. Orleman and J. Koutecky and J. Koryta, occurs according to the scheme... [Pg.361]

In the indirect amperometric method [560], saturated uranyl zinc acetate solution is added to the sample containing 0.1-10 mg sodium. The solution is heated for 30 minutes at 100 °C to complete precipitation. The solution is filtered and the precipitate washed several times with 2 ml of the reagent and then five times with 99% ethanol saturated with sodium uranyl zinc acetate. The precipitate is dissolved and diluted to a known volume. To an aliquot containing up to 1.7 mg zinc, 1M tartaric acid (2-3 ml) and 3 M ammonium acetate (8-10 ml) are added and the pH adjusted to 7.5-8.0 with 2 M aqueous ammonia. The solution is diluted to 25 ml and an equal volume of ethanol added. It is titrated amperometrically with 0.01 M K4Fe(CN)6 using a platinum electrode. Uranium does not interfere with the determination of sodium. [Pg.221]

SWV was used for the investigation of charge transfer kinetics of dissolved zinc(II) ions [215-218] and uranyl-acetylacetone [219], cadmium(II)-NTA [220] and mthenium(III)-EDTA complexes [221], and the mechanisms of electrode reactions of bismuth(III) [222], europium(III) [223,224] and indium(III) ions [225], 8-oxoguanine [226] and selenium(IV) ions [227,228]. It was also used for the speciation of zinc(II) [229,230], cadmium(II) and lead(II) ions in various matrices [231-235]. [Pg.154]

Serebrennikova, N.V., Kukushkina, I.I., and Plotnikova, N.V., A uranyl-selective membrane electrode based on a mixture of uranyl di-2-ethylhexyl phosphate and tributyl phosphate in benzene. Zhur. Anal. Khim. USSR, 1982, 37 645-649. [Pg.913]

Mikhajlov, V.A., Osipov, V.V., and Serebrennikova, N.V., Ion-selective electrode based on uranyl di-2-ethylhexylphosphate. Zhur. Anal. Khim USSR, 1978, 33 1154-1158. [Pg.913]

Current now tends to flow from the solution to the electrode Title-stad s expenments show that over the entire range of uranous-uranyl mixtures examined by him the electrode was positive with respect to the normal hydrogen half element, that is, reduction of uranyl was tending to take place The following numencal values are a few of those given by Titlestad, l c, and will illustrate the above processes —... [Pg.425]

To leach the more acid-resistant minerals containing tetravalent uranium, steam is fed to the second tank to bring the temperature to 49 to 60°C, and sodium chlorate NaQOj is added to bring the oxidation-reduction potential e, measured relative to the calomel electrode, to from —0.47 to —0.51 V. At —0.51 V, the equilibrium ratio of ferric iron to ferrous iron in the solution is 0.52. Ferric iron catalyzes the oxidation of insoluble tetravalent uranium to the soluble hexavalent uranyl form ... [Pg.243]

Figure 8.5.2 E-t curves for stepwise reduction of oxygen and uranyl ion at mercury electrode, a) 1 M LiCl solution saturated with oxygen at 25°C. O2 + 2H2O + 2e -> H2O2 + 20H H2O2 + 2e- 20H T2/T1 3. (/ ) 10 M uranyl nitrate in 0.1 M KCl + 0.01 M HCl. U(VI) + eU(V) U(V) + 2e U(III) T2/T1 8. [Reprinted with permission from T. Berzins and P. Delahay, J. Am. Chem. Soc., 75, 4205 (1953). Copyright 1953, American Chemical Society.]... Figure 8.5.2 E-t curves for stepwise reduction of oxygen and uranyl ion at mercury electrode, a) 1 M LiCl solution saturated with oxygen at 25°C. O2 + 2H2O + 2e -> H2O2 + 20H H2O2 + 2e- 20H T2/T1 3. (/ ) 10 M uranyl nitrate in 0.1 M KCl + 0.01 M HCl. U(VI) + eU(V) U(V) + 2e U(III) T2/T1 8. [Reprinted with permission from T. Berzins and P. Delahay, J. Am. Chem. Soc., 75, 4205 (1953). Copyright 1953, American Chemical Society.]...
Nitrates can also be determined after their reduction with zinc or cadmium amalgam to nitrites, employing photometry with sulphanilic acid and a-naphthylamine. In the case of polarographic determination nitrates are reduced on the mercury droping electrode in a weak acid medium under catalytic effects of uranyl ions. [Pg.316]

The recent literature in this area is focused on the electrochemistry of uranyl ions and complexes in mixtures of aqueous and organic solvents, the influence of different electrode surfaces and compositions, and the impact of the ligands surrounding the central uranyl moiety. [Pg.4204]


See other pages where Uranyl electrodes is mentioned: [Pg.106]    [Pg.106]    [Pg.230]    [Pg.459]    [Pg.463]    [Pg.476]    [Pg.440]    [Pg.1056]    [Pg.1057]    [Pg.1058]    [Pg.1059]    [Pg.1060]    [Pg.347]    [Pg.229]    [Pg.58]    [Pg.280]    [Pg.289]    [Pg.304]    [Pg.450]    [Pg.898]    [Pg.1056]    [Pg.1057]    [Pg.1058]    [Pg.1059]    [Pg.1060]    [Pg.425]    [Pg.425]    [Pg.425]    [Pg.427]    [Pg.428]    [Pg.292]    [Pg.213]    [Pg.593]    [Pg.542]    [Pg.569]    [Pg.707]    [Pg.4203]    [Pg.4205]    [Pg.4206]   


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Uranyl

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