Insights into the Coordination and Extraction of Yttrium(III) Ions with a Phenoxyacetic Acid Ionic‐Liquid Extractant

Phenoxyacetic acid type extractants such as sec‐octylphenoxyacetic acid (CA‐12), sec‐nonylphenoxyacetic acid (CA‐100), and the resulting bifunctional ionic‐liquid extractants were developed to separate yttrium from heavy rare‐earth elements (REEs). To obtain information on the coordination chemistry...

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Bibliographic Details
Published in:European journal of inorganic chemistry 2017-05, Vol.2017 (17), p.2332-2339
Main Authors: Guo, Xiang‐Guang, Yang, Ruo‐Ou, Gong, Yu, Jiang, Zheng, Dong, Yamin, Sun, Xiaoqi
Format: Article
Language:English
Subjects:
Acids
Chloride ions
Density functional calculations
Extraction
Infrared spectroscopy
Inorganic chemistry
Ionic liquids
Rare earths
Saponification
Single crystals
X-rays
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Summary:Phenoxyacetic acid type extractants such as sec‐octylphenoxyacetic acid (CA‐12), sec‐nonylphenoxyacetic acid (CA‐100), and the resulting bifunctional ionic‐liquid extractants were developed to separate yttrium from heavy rare‐earth elements (REEs). To obtain information on the coordination chemistry of this type of bifunctional ionic‐liquid extractant, the CA‐12 analogue n‐octylphenoxyacetic acid (HOCTPOA) was synthesized, and its structure was characterized by single‐crystal X‐ray diffraction analysis. Then, a bifunctional ionic‐liquid extractant based on HOCTPOA, namely, [N1888][OCTPOA] (N1888 is methyltrioctylammonium) was synthesized. The study of the extraction of yttrium with [N1888][OCTPOA] in chloride media was conducted by IR spectroscopy, log D versus log C slope analysis, ESI‐MS, extended X‐ray absorption fine structure (EXAFS), and DFT studies. The EXAFS data indicate that a YIII extraction complex with phenoxyacetic acid formed. Three possible YIII coordination cations were calculated by the DFT method, and the obtained Y–O bond lengths were comparable to the results from EXAFS fitting. A possible structure for the overall extracted complex was proposed, and this knowledge should contribute to a better understanding of the extraction process with phenoxyacetate‐type bifunctional ionic liquids. The ionic‐liquid extractant methyltrioctylammonium n‐octylphenoxyacetate ([N1888][OCTPOA]) is synthesized for the extraction of yttrium. The coordination of the extractant with Y is studied to provide insights into the extraction process.
ISSN:1434-1948
1099-0682
DOI:10.1002/ejic.201601491