Solubility of U(VI) in chloride solutions. II. The stable oxides/hydroxides in alkaline KCl solutions: Thermodynamic description and relevance in cementitious systems

Solubility of U(VI) in chloride solutions. II. The stable oxides/hydroxides in alkaline KCl solutions: Thermodynamic description and relevance in cementitious systems

The solubility of U(VI) is investigated from undersaturation conditions in 0.1, 0.51, 1.03, 3.31 and 4.58 m KCl–KOH solutions at pHm = 7.5–14.6 (with pHm = –log [H+] in molal units). All experiments were performed under Ar atmosphere at T = (22 ± 2)°C. XRD, quantitative chemical analysis, SEM–EDS an...

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Veröffentlicht in:Applied geochemistry 2018-11, Vol.98 (C), p.237-246
Hauptverfasser: Çevirim-Papaioannou, Neşe, Yalçıntaş, Ezgi, Gaona, Xavier, Altmaier, Marcus, Geckeis, Horst
Format: Artikel
Sprache:eng
Schlagworte:
Cement
Environmental Protection
GEOSCIENCES
Hydrolysis
KCl
MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
MATERIALS SCIENCE
SIT
Solubility
Thermodynamics
U(VI)
Uranium
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Zusammenfassung:The solubility of U(VI) is investigated from undersaturation conditions in 0.1, 0.51, 1.03, 3.31 and 4.58 m KCl–KOH solutions at pHm = 7.5–14.6 (with pHm = –log [H+] in molal units). All experiments were performed under Ar atmosphere at T = (22 ± 2)°C. XRD, quantitative chemical analysis, SEM–EDS and TG–DTA confirm that K2U2O7·1.5H2O(cr) is the solid phase controlling the solubility in all evaluated systems at pHm ≥ 9.5. Below this pHm and with decreasing KCl concentration, the formation of sub-stoichiometric phases with K:U 
ISSN:0883-2927
1872-9134
DOI:10.1016/j.apgeochem.2018.09.017