| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 211869 | Hydrometallurgy | 2016 | 5 Pages |
•The mechanism of REE ion adsorption by diglycolamic acid ligands was investigated.•Ether oxygen atoms in the ligands played a crucial role in REE ion adsorption.•Amide oxygen atoms in the ligands also participated in REE ion adsorption.•Exchange of the protons in the carboxylic acid group for REE ions also played a role.•Tridentate chelation by the diglycolamic acid ligands conferred high REE selectivity.
Previously, we investigated silica gel adsorbents bearing immobilized diglycolamic acid ligands (designated EDASiDGA) for the selective recovery of rare earth elements (REEs) from acidic solution, but the details of the adsorption mechanism remained to be elucidated. In this study, to clarify the adsorption mechanism, we prepared some derivatives of EDASiDGA and investigated the differences in their adsorption behaviors with respect to REE ions. On the basis of our results, we concluded that adsorbents with diglycolamic acid ligands adsorb REE ions via three oxygen atoms (that is, the ether, amide, and carboxylic acid oxygen atoms of the diglycolamic acid ligands) and that this tridentate chelation confers high selectivity for REE ions.
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