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Solubility properties of synthetic and natural meta-torbernite

Fanny Cretaz, Stéphanie Szenknect

2013ensolubilitymeta-torbernitethermodynamicsuraniumminerals

Abstract

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Meta-torbernite, Cu(UO2)2(PO4)2/C1 8H2O, is one of the most common secondary minerals resulting from the alteration of pitchblende. The determination of the thermodynamic data associated to this phase appears to be a crucial step toward understanding the origin of uranium deposits or forecasting the fate and transport of uranium in natural media. A parallel approach based on the study of both synthetic and natural samples of meta-torbernite (H3O)0.4Cu0.8(UO2)2(PO4)2/C1 7.6H2O was set up to evaluate its solubility constant. The two solids were first thoroughly characterized and compared using XRD, SEM, X-EDS analyses, Raman spectroscopy, and BET measurements. The solubility constant was then determined in both under- and supersaturated conditions: the obtained value appeared close to logK/C14s;0(298 K) =/C0 52.9 ± 0.1 whatever the type of experiment and the sample considered. The joint determination of Gibbs free energy (DRG/C176(298 K) = 300 ± 2 kJ mol/C0 1) then allowed the calculation of DRH/C176(298 K) = 40 ± 3 kJ mol/C0 1 and DRS/C176(298 K) =/C0 879 ± 7 J mol/C0 1 K/C0 1. From these values, the thermodynamic data associated with the formation of meta-torbernite (H3O)0.4Cu0.8(UO2)2(PO4)2/C1 7.6H2O were also evaluated and found to be consistent with those previously obtained by calorimetry, showing the reliability of the method developed in this work.

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Cite This Work

@article{3685aab8-fdf3-4509-a1c2-f43f06e1d6ef,
  title={Solubility properties of synthetic and natural meta-torbernite},
  author={Fanny Cretaz and Stéphanie Szenknect},
  year={2013},
  language={en}
}
TY  - JOUR
TI  - Solubility properties of synthetic and natural meta-torbernite
AU  - Fanny Cretaz
AU  - Stéphanie Szenknect
PY  - 2013
LA  - en
ER  -

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