『Abstract
The dissolution and growth of uranophane [Ca(UO2)2(SiO3OH)2・5H2O] have been examined in Ca- and Si-rich test
solutions at low temperatures (20.5±2.0℃) and near-neutral pH
(～6.0). Uranium-bearing experimental solutions undersaturated
and supersaturated with uranophane were prepared in matrices of
～10-2 M CaCl2 and ～10-3
M SiO2(aq) . The experimental solutions were
reacted with synthetic uranophane and analyzed periodically over
10 weeks. Interpretation of the aqueous solution data permitted
extraction of a solubility constant for the uranophane dissolution
reaction (ｌog Kspo = 11.01±0.09)
and standard state Gibbs free energy of formation for uranophane
(ΔGfo = -6196.1±0.5 kJ mol-1).』
1. Introduction
2. Experimental materials and methods
2.1. Uranophane synthesis
2.2. Dissolution and precipitation experiments
3. Results
3.1. Experimental data
3.1.1. Dissolution experiments
3.1.2. Precipitation experiments
3.2. Mass transfer relations
3.2.1. Dissolution experiments
3.2.2. Precipitation experiments
4. Discussion
4.1. Thermodynamic calculations
4.2. Evaluation of soddyite precipitation
4.3. Extraction of ｌog Kspo for
uranophane dissolution
5. Conclusions
Acknowledgments
References