Influence of (Calcium−)Uranyl−Carbonate Complexation on U(VI) Sorption on Ca- and Na-Bentonites

2009 ◽  
Vol 43 (13) ◽  
pp. 4896-4901 ◽  
Author(s):  
A. Meleshyn ◽  
M. Azeroual ◽  
T. Reeck ◽  
G. Houben ◽  
B. Riebe ◽  
...  
Keyword(s):  
Uranyl Carbonate ◽  
Carbonate Complexation

scholarly journals The crystal structures and mechanical properties of the uranyl carbonate minerals roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite

2020 ◽  
Vol 7 (21) ◽  
pp. 4197-4221 ◽  
Author(s):  
Francisco Colmenero ◽  
Jakub Plášil ◽  
Jiří Sejkora
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonding ◽  
Diffraction Pattern ◽  
Crystal Structures ◽  
First Principles ◽  
X Ray Diffraction ◽  
Carbonate Minerals ◽  
X Ray ◽  
Uranyl Carbonate

The structure, hydrogen bonding, X-ray diffraction pattern and mechanical properties of six important uranyl carbonate minerals, roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite, are determined using first principles methods.

The crystal chemistry of the uranyl carbonate mineral grimselite, (K, Na)3Na[(UO2)(CO3)3](H2O), from Jáchymov, Czech Republic

2012 ◽  
Vol 76 (3) ◽  
pp. 443-453 ◽  
Author(s):  
J. Plášil ◽  
K. Fejfarová ◽  
R. Skála ◽  
R. Škoda ◽  
N. Meisser ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Czech Republic ◽  
Structure Refinement ◽  
Unit Cell ◽  
Carbonate Mineral ◽  
X Ray Diffraction ◽  
The Czech Republic ◽  
Cell Parameters ◽  
Uranyl Carbonate ◽  
Diffraction Peaks

AbstractTwo crystals of the uranyl carbonate mineral grimselite, ideally K3Na[(UO2)(CO3)3](H2O), from Jáchymov in the Czech Republic were studied by single-crystal X-ray diffraction and electron-probe microanalysis. One crystal has considerably more Na than the ideal chemical composition due to substitution of Na into KO8 polyhedra; the composition of the other crystal is nearer to ideal, and similar to synthetic grimselite. The presence of Na atoms in KO8 polyhedra, which are located in channels in the crystal structure, reduces their volume, and as a result the unit-cell volume also decreases. Structure refinement shows that the formula for the sample with the anomalously high Na content is (K2.43Na0.57)Σ3.00Na[(UO2)(CO3)3](H2O). The unit-cell parameters, refined in space group P2c, are a = 9.2507(1), c = 8.1788(1) Å, V = 606.14(3) Å3 and Z = 2. The crystal structure was refined to R1 = 0.0082 and wR1 = 0.0185 with a GOF = 1.33, based on 626 observed diffraction peaks [Iobs>3σ(I)].

CO 2 in haplo-phonolite melt: solubility, speciation and carbonate complexation

2002 ◽  
Vol 66 (10) ◽  
pp. 1809-1820 ◽  
Author(s):  
Y. Morizet ◽  
R.A. Brooker ◽  
S.C. Kohn
Keyword(s):  
Carbonate Complexation

scholarly journals Uranium-thorium mineralization process of the Ukrainian shield suture zones and evolution of the composition of depth fluids in Precambrian

2020 ◽  
pp. 45-53
Author(s):  
O.V. Usenko ◽  
Keyword(s):  
Geological Structure ◽  
Complex Compounds ◽  
Ukrainian Shield ◽  
Mineralization Process ◽  
Chloride Complexes ◽  
Geochemical Properties ◽  
Carbonate Ions ◽  
Uranyl Carbonate ◽  
Group Reduction ◽  
Acid Reaction

Тhe geochemical properties of uranium and thorium and the geological structure of the ore oc currences of the Golovanevskaya and Ingulo-Inguletskaya suture zones are correlated with changes in the composition of mantle melts and fluids in the Archean-Paleoproterozoic. It is shown that the formation of uranium and thorium deposits on the Ukrainian shield became possible in the Proterozoic, when oxidized and acidic melts prevailing in the Archean mantle were replaced by neutral and alkaline water-chloride-potassium. This led to the accumulation of tho rium (to a greater extent) and uranium (to a less extent) in granite magmas of the layer of partial melting of the crust, where they entered as chloride complexes. The ore occurrences of monazite in microcline granites and pegmatites of the Berdichev and Kirovograd complexes formed in the period 2.1-1.9 billion years ago are associated with these processes. The enrichment of crustal centers of melting with uranium occurred most intensively after 2.0 billion years ago (a maximum of 1.8-1.65 billion years ago), when uranyl-carbonate ions entered the crust as a part of mantle carbonate-fluoride-sodium fluids, they were mixed with melts of existing melting centers. A change in the pH of the medium led to the decomposition of complex compounds and the release of the uranyl group, reduction of uranium to U4+ in the presence of graphite and magnetite, and at geochemical barriers with an acid reaction, and the activity of hydroxyl ions ensured the creation of a brannerite structure.

Carbonate Complexation of Neptunyl(VI) Ion

1998 ◽  
Vol 82 (s1) ◽  
Author(s):  
Yoshiharu Kato ◽  
Takaumi Kimura ◽  
Zenko Yoshida ◽  
Noriko Nitani
Keyword(s):  
Carbonate Complexation
Sign in / Sign up

Export Citation Format

Share Document