Temat: uranyl ion - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Kinetics of uranyl ion polymerization in the presence of ammonium hydroxide
Autorzy:: Abdelrazek, I.
Zidan, W.
Farag, H.
Barakat, M.
Tematy:: uranyl ion
hydrolysis
kinetics
polymerization; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/148783.pdf Link otwiera się w nowym oknie
Opis:: Kinetics of the polymerization of UO2 2+ ion to UO2[(OH)2UO2]4 2+ in the ammonia-uranyl nitrate system has been studied. The deepening of the color formed with the addition of ammonia made it possible to estimate spectrophotometrically the concentration of the formed UO2[(OH)2UO2]4 2+ ions in the solution at 420.6 nm. The effects of pH, temperature as well as the concentration of uranyl ion have been investigated. The reaction rate equation for the polymerization reaction is presented. Linear dependencies of logarithm of the apparent reaction-rate constant on both pH and the reverse of temperature were observed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Application of Pt/Al2O3 catalysts produced by sol-gel process to uranyl ion reduction
Autorzy:: Deptuła, A.
Łada, W.
Olczak, T.
Chmielewski, A.
Tematy:: sol-gel
Pt/Al2O3 catalysts
uranyl ion reduction; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/146103.pdf Link otwiera się w nowym oknie
Opis:: Various kinds of active alumina supports were obtained by the Institute of Nuclear Chemistry and Technology (INCT) sol-gel process in the following steps: (1) preparation of alumina sols by extraction of nitrates with Primene JMT from aluminium nitrate solution; (2) gelation to spherical particles (with diameter < 100 žm) by extraction of water from sol emulsion in 2-ethyl-1-hexanol; (3) sometimes conversion of NO3 - stabilized gel to OH- form by reaction with ammonia; (4) calcination of gels to ?-Al2O3 with specific surface area > 100 m2/g at 500°C. The powders were then impregnated with chloroplatinic acid and recalcined at 500°C. Catalysts were also prepared by direct gelation of alumina sol containing hydroplatinic acid followed by steps (3) and (4). Pt/Al2O3 catalysts were used for the reduction of 1M UO2(NO3)2 - 0.5M HCOOH solution with hydrogen at atmospheric pressure. The course of the reduction was controlled analytically and by measuring the U(VI)/U(IV) redox potential. It was concluded that the catalysts obtained by impregnation of the supports prepared from nitrate stabilized gels exhibit the best activity and stability.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Determination of formation constants of uranyl(VI) complexes with a hydrophilic SO3-Ph-BTP ligand, using liquid-liquid extraction
Autorzy:: Steczek, L.
Narbutt, J.
Charbonnel, M. -C.
Moisy, P.
Tematy:: uranyl ion
hydrophilic poly-N-dentate ligands
complexes
solvent extraction
stripping
formation constant; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/147774.pdf Link otwiera się w nowym oknie
Opis:: Complex formation between uranyl ion, UO2 2+, and a hydrophilic anionic form of SO3-Ph-BTP4– ligand, L4–, in water was studied by liquid-liquid extraction experiments performed over a range of the ligand and HNO3 concentrations in the aqueous phase, at a constant concentration of nitrate anions at 25°C . The competition for UO2 2+ ions between the lipophilic TODGA extractant and the hydrophilic L4– ligand leads to the decrease in the uranyl distribution ratios, D, with an increasing L4– concentration. The model of the solvent extraction process used accounts – apart from uranyl complexation by TODGA and SO3-Ph-BTP4– – also for uranyl complexation by nitrates and for the decrease in the concentration of the free L4– ligand in the aqueous phase, due to its protonation, bonding in the uranyl complex and the distribution between the two liquid phases. The unusually strong dependence of the D values on the acidity, found in the experiment, could hardly be explained as due to L4– protonation merely. Three hypotheses were experimentally tested, striving to interpret the data in terms of additional extraction to the organic phase of ion associates of protonated TODGA cation with either partly protonated anionic L4– ligands or anionic UO2 2+ complexes with NO3 – or L4–. None of them has been confi rmed. The analysis of the results, based on the formal correction of free ligand concentrations, points to the formation of 1 : 1 and 1 : 2 uranyl – SO3-Ph-BTP complexes in the aqueous phase. The conditional formation constant of the 1:1 complex has been determined, logβL,1 = 2.95 ± 0.15.
Dostawca treści:: Biblioteka Nauki

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