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Temperature effects on the interaction mechanisms between U(VI) and Eu(III) and ZrP2O7: experiment and modelling
Finck N., Drot R., Lagarde G., Mercier-Bion F., Catalette H. et al
Radiochimica Acta 96 (2008) 11-21 - http://hal.in2p3.fr/in2p3-00258842
Temperature effects on the interaction mechanisms between U(VI) and Eu(III) and ZrP2O7: experiment and modelling
N. Finck1, R. Drot1, G. Lagarde1, Florence Mercier-Bion1, H. Catalette1, E. Simoni1
1 :  IPNO - Institut de Physique Nucléaire d'Orsay
CNRS : UMR8608 – IN2P3 – Université Paris XI - Paris Sud
IPN - 15, rue Georges Clemenceau - 91406 ORSAY CEDEX
In the field of nuclear waste management, prediction of the radionuclides migration through the geosphere has to take into account the effects of temperature. The chosen substrate, zirconium diphosphate, was previously described concerning its surface acidity properties for several temperatures (25 °C, 50 °C, 75 °C, 90 °C). Edges for uranyl sorption were obtained in NaClO4 medium, and the europium(III) sorption edges were realized in KNO3 medium to evaluate the influence of the complexing nitrate ions. Influence of the temperature, the nature of the cation and the nature of the substrate were pointed out by comparing the edges for the different systems. A structural investigation (TRLFS) was carried out to define experimentally, at the microscopic level, the sorption equilibria. Only UO22+ and Eu3+ were sorbed on both ZrP2O7 surface sites (≡Zr–O and ≡P–O), the nitrate medium having no influence on the sorbed species. Furthermore, temperature did not change the sorption mechanisms. The surface complexation modelling of both investigated systems was realized using i) the constant capacitance model ii) the results of the substrate characterizations iii) uranyl sorbed complex detes onto the ≡Zr–O site is not accompanied by a proton rease, whereas the formation of bidentate surface complexes onto the ≡P–O site is followed by a release of 2 protons, for both cations and at all temperatures studied. The determined sorption constants increase with temperature, as was expected from the analysis of the sorption edge positions.

Articles dans des revues avec comité de lecture
Radiochimica Acta (Radiochim. Acta)
Publisher R Oldenbourg Verlag GMBH
ISSN 0033-8230 

Sorption – Uranium – Europium – Zirconium diphosphate – Temperature – TRLFS – Speciation – Modelling – Surface complexation