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Investigating Metal-Tributyl Phosphate Complexes during Supercritical Fluid Extraction of the NdFeB Magnet Using
Jiakai Zhang1, Ning Chen2, Valeria Morozova3
1Laboratory for Strategic Materials, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada.
Inorganic Chemistry
|May 8, 2023
Summary
Supercritical fluid extraction (SCFE) offers green recycling for waste electronics. This study reveals the complexation chemistry of rare-earth elements during SCFE of NdFeB magnets, clarifying the recycling mechanism.
Area of Science:
- Materials Science
- Green Chemistry
- Computational Chemistry
Background:
- Supercritical fluid extraction (SCFE) is an emerging green technology for recycling waste electrical and electronic equipment (WEEE).
- Neodymium iron boron (NdFeB) magnets in end-of-life products are valuable sources of critical rare-earth elements (REEs).
- The detailed mechanism of SCFE for NdFeB magnet recycling remains largely unexplored.
Purpose of the Study:
- To elucidate the complexation chemistry and mechanism of supercritical fluid extraction (SCFE) for recycling Neodymium iron boron (NdFeB) magnets.
- To determine the structural coordination and interatomic interactions of complexes formed during the SCFE process.
- To provide a theoretical foundation for optimizing SCFE processes for rare-earth element recovery.
Main Methods:
- Density functional theory (DFT) calculations were employed to model complex formation.
- Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) analyses were used to validate theoretical models.
- Investigation focused on the interactions between metal ions (Fe, Nd) and extractants under SCFE conditions.
Main Results:
- DFT calculations predicted the formation of specific metal complexes: Fe(NO3)2(TBP)2, Fe(NO3)3(TBP)2, and Nd(NO3)3(TBP)3.
- EXAFS and XANES analyses provided experimental evidence supporting the proposed structural models and coordination environments.
- The study identified key interatomic interactions governing the complexation and extraction of REEs from NdFeB magnets.
Conclusions:
- The research successfully elucidated the complexation chemistry and mechanism of SCFE for NdFeB magnets.
- The findings provide crucial insights into the structural models and interactions involved in rare-earth element recovery.
- This theory-guided approach enhances the understanding and optimization of green recycling technologies for critical materials.
