Effect of organophosphorus ligands on supercritical extraction of neodymium from NdFeB magnet

Kunanusont, Nattanai; Zhang, Jiakai; Watada, Kimberly; Shimoyama, Yusuke; Azimi, Gisele

doi:10.1016/j.supflu.2020.105128

Cited by 8 publications

(4 citation statements)

References 48 publications

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“…4,5 Not only does the adduct accommodate the polarity difference, but it also satisfies charge neutrality and improves solvent−solute interactions. 7 In our previous studies, we proposed extraction mechanisms for the SCFE of REEs from the nickel metal hydride (NiMH) battery, NdFeB magnets, and fluorescent lamps (FLs). 2,4,5 In the proposed mechanism, the bidentate nitrate anions from the TBP−HNO 3 adduct chelate to REE cations, forming neutral rare-earth nitrates, REE(NO 3 ) 3 .…”

Section: Introductionmentioning

confidence: 99%

“…SCFE is a complex but promising process that is poorly understood; therefore, there is an immediate need for fundamental and applied research in this field. In a recent study by our group, we successfully developed, for the first time, a SCFE process utilizing supercritical carbon dioxide (sc-CO 2 ) as the solvent along with a small amount of TBP–HNO 3 adduct as the complexing agent to recycle REEs from NdFeB magnets. , The mechanism of the extraction process in the presence of supercritical fluids is unknown, and this information is critical to determine the effectiveness and environmental impact of this process.…”

Section: Introductionmentioning

confidence: 99%

“…The produced metal–ligand complex is non-polar and dissolvable in sc-CO 2 . In a previous study by our group, the effect of four organophosphorus ligands (triethyl phosphate, tributyl phosphate, tributyl phosphine oxide, and trioctyl phosphine oxide) on neodymium extraction efficiency from the NdFeB magnet using SCFE was investigated . Scholars have reported that the TBP and nitric acid (HNO 3 ) adduct can react with metals, forming stable hydrophobic complexes. , Not only does the adduct accommodate the polarity difference, but it also satisfies charge neutrality and improves solvent–solute interactions .…”

Section: Introductionmentioning

confidence: 99%

“…In a previous study by our group, the effect of four organophosphorus ligands (triethyl phosphate, tributyl phosphate, tributyl phosphine oxide, and trioctyl phosphine oxide) on neodymium extraction efficiency from the NdFeB magnet using SCFE was investigated . Scholars have reported that the TBP and nitric acid (HNO 3 ) adduct can react with metals, forming stable hydrophobic complexes. , Not only does the adduct accommodate the polarity difference, but it also satisfies charge neutrality and improves solvent–solute interactions . In our previous studies, we proposed extraction mechanisms for the SCFE of REEs from the nickel metal hydride (NiMH) battery, NdFeB magnets, and fluorescent lamps (FLs). ,, In the proposed mechanism, the bidentate nitrate anions from the TBP–HNO 3 adduct chelate to REE cations, forming neutral rare-earth nitrates, REE(NO 3 ) 3 .…”

Section: Introductionmentioning

confidence: 99%

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Investigating Metal–Tributyl Phosphate Complexes during Supercritical Fluid Extraction of the NdFeB Magnet Using Density Functional Theory and X-ray Absorption Spectroscopy

et al. 2023

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Supercritical fluid extraction (SCFE) is gaining significant interest as a green technology for the recycling of endof-life waste electrical and electronic equipment (WEEE). Neodymium iron boron (NdFeB) magnets, which contain large quantities of critical rare-earth elements such as neodymium, praseodymium, and dysprosium, are widely used in wind turbines and electric/hybrid vehicles. Hence, they are considered a promising secondary resource for these elements when they reach their end-of-life. Previously, the SCFE process was developed for recycling WEEE, including NdFeB; however, the process mechanism remains unexplored. Here, density functional theory, followed by extended X-ray absorption fine structure and X-ray absorption near-edge structure analyses, are utilized to determine the structural coordination and interatomic interactions of complexes formed during the SCFE of the NdFeB magnet. The results indicate that Fe(II), Fe(III), and Nd(III) form Fe(NO 3 ) 2 (TBP) 2 , Fe(NO 3 ) 3 (TBP) 2 , and Nd(NO 3 ) 3 (TBP) 3 complexes, respectively. This theory-guided investigation elucidates the complexation chemistry and mechanism during the SCFE process by rigorously determining the structural models.

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