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Lookup NU author(s): Dr Shannon FlynnORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2024 American Chemical Society.The energy transition will have significant mineral demands and there is growing interest in recovering critical metals, including rare earth elements (REE), from secondary sources in aqueous and sedimentary environments. However, the role of clays in REE transport and deposition in these settings remains understudied. This work investigated REE adsorption to the clay minerals illite and kaolinite through pH adsorption experiments and extended X-ray absorption fine structure (EXAFS). Clay type, pH, and ionic strength (IS) affected adsorption, with decreased adsorption under acidic pH and elevated IS. Illite had a higher adsorption capacity than kaolinite; however, >95% adsorption was achieved at pH ∼7.5 regardless of IS or clay. These results were used to develop a surface complexation model with the derived binding constants used to predict REE speciation in the presence of competing sorbents. This demonstrated that clays become increasingly important as pH increases, and EXAFS modeling showed that REE can exist as both inner- and outer-sphere complexes. Together, this indicated that clays can be an important control on the transport and enrichment of REE in sedimentary systems. These findings can be applied to identify settings to target for resource extraction or to predict REE transport and fate as a contaminant.
Author(s): Bishop BA, Alam MS, Flynn SL, Chen N, Hao W, Ramachandran Shivakumar K, Swaren L, Gutierrez Rueda D, Konhauser KO, Alessi DS, Robbins LJ
Publication type: Article
Publication status: Published
Journal: Environmental Science and Technology
Year: 2024
Volume: 58
Issue: 16
Pages: 7217-7227
Print publication date: 23/04/2024
Online publication date: 08/04/2024
Acceptance date: 29/03/2024
Date deposited: 30/04/2024
ISSN (print): 0013-936X
ISSN (electronic): 1520-5851
Publisher: American Chemical Society
URL: https://doi.org/10.1021/acs.est.4c00974
DOI: 10.1021/acs.est.4c00974
ePrints DOI: 10.57711/ngt5-3339
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