TY - JOUR
T1 - Modeling phase equilibria and speciation in aqueous solutions of rare earth elements with hydroxide and organic ligands
AU - Das, Gaurav
AU - Lencka, Malgorzata M.
AU - Liu, Jiangping
AU - Anderko, Andrzej
AU - Riman, Richard E.
AU - Navrotsky, Alexandra
N1 - Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/11
Y1 - 2023/11
N2 - A thermodynamic model has been developed for calculating speciation and phase equilibria in aqueous solutions of rare earth elements (REEs) with hydroxide, acetate, citrate, and oxalate anions. The computational framework is based on the Mixed-Solvent Electrolyte (MSE) framework, which has been previously used to establish a systematic treatment of binary and multicomponent systems containing REE sulfates and chlorides up to solid–liquid saturation at temperatures up to 300 °C. The model has been parametrized by performing a multi-property analysis of critically evaluated speciation and solubility data. For rare earth hydroxides, a comprehensive model has been developed for fourteen REEs (i.e., for yttrium and all lanthanides except promethium). The effect of the crystallinity of rare earth hydroxides on their solubility has been analyzed. Model parameters have been determined for two limiting cases, i.e., for crystalline and amorphous hydroxides, while recognizing that the hydroxides may span a range of degrees of crystallinity. For the organic ligands, the model has been established for neodymium with additional analysis for other selected REEs. The model accurately reproduces the effects of pH, temperature, and complexation with organic ligands on the behavior of rare earth elements in aqueous solutions. When coupled with previously developed models for inorganic rare earth salts, it provides a thermodynamic tool for the design and optimization of separation processes for the production and recycling of REEs and for predicting the properties of REEs in geological and biological settings.
AB - A thermodynamic model has been developed for calculating speciation and phase equilibria in aqueous solutions of rare earth elements (REEs) with hydroxide, acetate, citrate, and oxalate anions. The computational framework is based on the Mixed-Solvent Electrolyte (MSE) framework, which has been previously used to establish a systematic treatment of binary and multicomponent systems containing REE sulfates and chlorides up to solid–liquid saturation at temperatures up to 300 °C. The model has been parametrized by performing a multi-property analysis of critically evaluated speciation and solubility data. For rare earth hydroxides, a comprehensive model has been developed for fourteen REEs (i.e., for yttrium and all lanthanides except promethium). The effect of the crystallinity of rare earth hydroxides on their solubility has been analyzed. Model parameters have been determined for two limiting cases, i.e., for crystalline and amorphous hydroxides, while recognizing that the hydroxides may span a range of degrees of crystallinity. For the organic ligands, the model has been established for neodymium with additional analysis for other selected REEs. The model accurately reproduces the effects of pH, temperature, and complexation with organic ligands on the behavior of rare earth elements in aqueous solutions. When coupled with previously developed models for inorganic rare earth salts, it provides a thermodynamic tool for the design and optimization of separation processes for the production and recycling of REEs and for predicting the properties of REEs in geological and biological settings.
KW - Electrolytes
KW - Lanthanides
KW - Phase equilibria
KW - Rare earths
KW - Solid–liquid equilibria
KW - Solubility
KW - Speciation
KW - Thermodynamic modeling
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U2 - 10.1016/j.jct.2023.107125
DO - 10.1016/j.jct.2023.107125
M3 - Article
AN - SCOPUS:85167784907
SN - 0021-9614
VL - 186
JO - Journal of Chemical Thermodynamics
JF - Journal of Chemical Thermodynamics
M1 - 107125
ER -