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A calorimetric study of the hydrolysis and peroxide complex formation of the uranyl(vi) ionElectronic supplementary information (ESI) available: Table S1 Titrations carried out to determine the enthaply of formation of water and HO2−. Table S2 Titrations carried out to determine the enthaply of formation of uranyl(vi) hydroxide complexes in acid and in basic solution. Table S3 Titrations carried out to measure the enthalpy changes of the uranyl(vi)-hydroxide-peroxide complexes in basic solution.
The enthalpies of reaction for the formation of uranyl( vi ) hydroxide {[(UO 2 ) 2 (OH) 2 ] 2+ , [(UO 2 ) 3 (OH) 4 ] 2+ , [(UO 2 ) 3 (OH) 5 ] + , [(UO 2 ) 3 (OH) 6 ] (aq) , [(UO 2 ) 3 (OH) 7 ] − , [(UO 2 ) 3 (OH) 8 ] 2− , [(UO 2 )(OH) 3 ] − , [(UO 2 )(OH) 4 ] 2− } and peroxide complexes {[UO 2 (O 2...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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| Summary: | The enthalpies of reaction for the formation of uranyl(
vi
) hydroxide {[(UO
2
)
2
(OH)
2
]
2+
, [(UO
2
)
3
(OH)
4
]
2+
, [(UO
2
)
3
(OH)
5
]
+
, [(UO
2
)
3
(OH)
6
]
(aq)
, [(UO
2
)
3
(OH)
7
]
−
, [(UO
2
)
3
(OH)
8
]
2−
, [(UO
2
)(OH)
3
]
−
, [(UO
2
)(OH)
4
]
2−
} and peroxide complexes {[UO
2
(O
2
)(OH)]
−
and [(UO
2
)
2
(O
2
)
2
(OH)]
−
} have been determined from calorimetric titrations at 25 °C in a 0.100 M tetramethyl ammonium nitrate ionic medium. The hydroxide data have been used to test the consistency of the extensive thermodynamic database published by the Nuclear Energy Agency (I. Grenthe, J. Fuger, R. J. M. Konings, R. J. Lemire, A. B. Mueller, C. Nguyen-Trung and H. Wanner,
Chemical Thermodynamics of Uranium
, North-Holland, Amsterdam, 1992 and R. Guillaumont, T. Fanghänel, J. Fuger, I. Grenthe, V. Neck, D. J. Palmer and M. R. Rand,
Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium
, Elsevier, Amsterdam, 2003). A brief discussion is given about a possible structural relationship between the trinuclear complexes [(UO
2
)
3
(OH)
n
]
6−
n
,
n
= 4-8.
The enthalpies of reaction for the formation of uranyl(
vi
) hydroxide and peroxide complexes have been determined from calorimetric titrations at 25 °C in a 0.100 M tetramethyl ammonium nitrate ionic medium. The hydroxide data suggest structural relationship between the complexes [(UO
2
)
3
(OH)
n
]
6−
n
,
n
= 4-8. |
|---|---|
| ISSN: | 1477-9226 1477-9234 |
| DOI: | 10.1039/c3dt52922c |