Adsorption of Rare Earth Elements to Kaolinite [dataset]
Abstract
Rare earth elements (REEs) are critical components of modern technology behind renewable energy, transportation, and electronics but have a limited current supply. A substantial portion of global REE production relies on ion adsorption deposits. A high abundance of kaolinite in REE enrichment zones within these deposits suggests that kaolinite controls the subsurface migration of REEs. This study aimed to improve the current understanding of REE binding to kaolinite under varying water chemistry conditions. We conducted batch experiments with kaolinite (KGa-2) and three REEs (Nd, Dy, and Yb) at varying pH, electrolyte concentration, dissolved inorganic carbon (DIC), low molecular weight organic acids (citric and oxalic acids), and total REE concentration conditions. Increasing electrolyte concentration inhibits REE adsorption at pH 7, suggesting that ion exchange contributes to adsorption at these pH values. DIC affects adsorption above pH 7−8 by forming strong aqueous complexes with heavy REEs. Citric acid decreases REE adsorption via aqueous complexation of REEs at pH 5 but does not affect adsorption at pH 5. The surface complexation model captures the main adsorption trends with two mechanisms: ion exchange on basal planes at pH ∼6 and inner-sphere surface complexation to edge sites at pH ∼6. Equilibrium constants for surface complexationmore »
- Authors:
-
- Washington University in St. Louis
- Publication Date:
- DOE Contract Number:
- SC0022213
- Research Org.:
- Washington University in St. Louis
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB)
- Subject:
- 58 GEOSCIENCES; Rare earth elements; clay; critical minerals; kaolinite; surface complexation modeling
- OSTI Identifier:
- 2570438
- DOI:
- https://doi.org/10.7936/6rxs-108281
Citation Formats
Ramazanova, Elimira, Sharma, Neha, Flynn, Elaine D, Stagg, Olwen, Catalano, Jeffrey G, and Giammar, Daniel E. Adsorption of Rare Earth Elements to Kaolinite [dataset]. United States: N. p., 2025.
Web. doi:10.7936/6rxs-108281.
Ramazanova, Elimira, Sharma, Neha, Flynn, Elaine D, Stagg, Olwen, Catalano, Jeffrey G, & Giammar, Daniel E. Adsorption of Rare Earth Elements to Kaolinite [dataset]. United States. doi:https://doi.org/10.7936/6rxs-108281
Ramazanova, Elimira, Sharma, Neha, Flynn, Elaine D, Stagg, Olwen, Catalano, Jeffrey G, and Giammar, Daniel E. 2025.
"Adsorption of Rare Earth Elements to Kaolinite [dataset]". United States. doi:https://doi.org/10.7936/6rxs-108281. https://www.osti.gov/servlets/purl/2570438. Pub date:Wed Jun 25 04:00:00 UTC 2025
@article{osti_2570438,
title = {Adsorption of Rare Earth Elements to Kaolinite [dataset]},
author = {Ramazanova, Elimira and Sharma, Neha and Flynn, Elaine D and Stagg, Olwen and Catalano, Jeffrey G and Giammar, Daniel E},
abstractNote = {Rare earth elements (REEs) are critical components of modern technology behind renewable energy, transportation, and electronics but have a limited current supply. A substantial portion of global REE production relies on ion adsorption deposits. A high abundance of kaolinite in REE enrichment zones within these deposits suggests that kaolinite controls the subsurface migration of REEs. This study aimed to improve the current understanding of REE binding to kaolinite under varying water chemistry conditions. We conducted batch experiments with kaolinite (KGa-2) and three REEs (Nd, Dy, and Yb) at varying pH, electrolyte concentration, dissolved inorganic carbon (DIC), low molecular weight organic acids (citric and oxalic acids), and total REE concentration conditions. Increasing electrolyte concentration inhibits REE adsorption at pH 7, suggesting that ion exchange contributes to adsorption at these pH values. DIC affects adsorption above pH 7−8 by forming strong aqueous complexes with heavy REEs. Citric acid decreases REE adsorption via aqueous complexation of REEs at pH 5 but does not affect adsorption at pH 5. The surface complexation model captures the main adsorption trends with two mechanisms: ion exchange on basal planes at pH ∼6 and inner-sphere surface complexation to edge sites at pH ∼6. Equilibrium constants for surface complexation increase in the order of Yb Dy Nd, indicating a higher strength of adsorption for heavy REEs. This study demonstrates how water chemistry conditions control the adsorption mechanisms that may determine the mobility of REEs in subsurface environments rich in kaolinite.},
doi = {10.7936/6rxs-108281},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jun 25 04:00:00 UTC 2025},
month = {Wed Jun 25 04:00:00 UTC 2025}
}
