The solubility of La hydroxide and stability of La3+ and La hydroxyl complexes at acidic to mildly acidic pH from 25 to 250 °C
Description
Batch-type hydrothermal solubility experiments were conducted using synthetic La hydroxide powders equilibrated in perchloric acid-based aqueous solutions at temperatures between 150 and 250 °C and starting pH of 2 to 5. The La hydroxide solubility is retrograde with temperature and displays a strong pH dependence with a decrease in La concentrations from acidic to mildly acidic pH spanning between 3 to 5 orders of magnitude (e.g. log La molality of -2.5 to -7.2 at 250 °C). Thermodynamic optimizations using GEMSFITS allow to retrieve the standard partial molal Gibbs energies for the La3+ aqua ion and the formation constants for the La hydroxyl species (i.e., LaOH2+, La(OH)2+, La(OH)30) between 25 and 250 °C.
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Funding
U.S. Department of Energy
Office of Science, Office of Basic Energy Sciences, Geosciences program under Award Number DE-SC0021106
Basic Energy Sciences
U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences program, DE-SC0022269