Competitive complexation of solid lanthanide nitrates with tri-n-butyl phosphate in n-hexane

Wang, Zhuangfei; Liu, Tingting; He, Xihong; Zhu, Liyang; He, Hui

doi:10.1007/s10967-016-5027-7

Cited by 7 publications

(5 citation statements)

References 19 publications

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“…The fitted average Nd–O bond based on the Nd(NO 3 ) 2 (TBP) 4 + model (2.49 Å) is longer in comparison with the DFT prediction value (Table ). The total coordination number (CN) fitted by using the Nd(NO 3 ) 3 (TBP) 4 model is 9.2 (Table ), close to the DFT models (CN = 8) and literature values (CN = 7–10). ,, The Nd(NO 3 ) 2 (TBP) 4 + model fitted to CN is 15.6 (Table ), which is double in comparison with the DFT prediction and literature values. Moreover, the fitting upon outer shell bonding by the Nd(NO 3 ) 3 (TBP) 4 model is close to the DFT estimation, but the fitting resulted by the Nd(NO 3 ) 2 (TBP) 4 + model significantly deviated from it (Table ).…”

Section: Resultssupporting

confidence: 73%

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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Section: Resultssupporting

confidence: 73%

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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“…Samarium oxide should behave similarly to Nd oxide, but another heavier lanthanide oxide like Ho2O3 might need to be included to help understand why the Er2O3 did not fully go into the organic phase at twice the time it took Nd2O3. This observation might indicate a competitive complexation between the heavier and lighter lanthanides, as was seen for Nd and Ho [9]. This study could expand to consider dissolving multiple oxides at once, in which case taking the second derivative of the spectra can help resolve the lanthanide oxide dissolution kinetics [12].…”

Section: Future Workmentioning

confidence: 64%

“…As soon as the neodymium oxide (Nd2O3) was added to the organic solution, spectra peaks similar to Nd(NO3)3•TBP3 in n-hexane [9] could be distinguished within seconds. As shown in Figure 2, several peaks were higher than 0.5 absorbance at the target concentration of 0.05 M. Interestingly, the spectra do not show distinct peaks associated with other Nd-containing species, specifically Nd2O3 [11].…”

Section: Neodymium Oxide Dissolutionmentioning

confidence: 99%

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Preliminary Result from the Dissolution of Neodymium and Erbium Oxide in a Tributyl Phosphate Solvent

GOGOLSKI¹,

Rudisill²,

Lascola³

et al. 2022

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This work demonstrated that visible absorbance spectroscopy can track the dissolution of neodymium and erbium oxide in an organic solution containing tributyl phosphate and nitrates. The formation of an aqueous phase was unexpected but an important phenomenon to consider when developing a metal oxide dissolution in organic solution flowsheet. Since the metal oxide appeared to completely dissolve into either the organic or newly formed aqueous phase, dissolution (extraction) rates should be easier to determine.

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“…As more TBP molecules surround the central ion, the complex is progressively dehydrated. Although there is some dispute on this topic, most studies suggest that lanthanides complexed with three or more TBP molecules have fully dehydrated inner coordination spheres, although some dynamic exchange of water in and out of the inner coordination sphere is possible. ,,− As more TBP molecules substitute for coordinated water molecules, the complex becomes better shielded with nonpolar butyl groups and eventually becomes soluble in the organic or supercritical phase. TBP binding affinity increases with atomic number due to the stronger binding forces associated with the smaller atomic radius of the lanthanide.…”

Section: Mechanismmentioning

confidence: 99%

Supercritical Extraction of Lanthanide Tributyl Phosphate Complexes: Current Status and Future Directions

Sinclair

Tester

Thompson

et al. 2019

Ind. Eng. Chem. Res.

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Many researchers have studied the extraction of lanthanides with tributyl phosphate in supercritical carbon dioxide. Potential applications include the enhanced extraction or separation of lanthanides from ores and recycled materials by making use of the unique solvation properties of supercritical CO2. In some cases, tributyl phosphate has been used to extract lanthanides from their solid nitrate salt form or from nitrate solutions. In other cases, tributyl phosphate/nitric acid adducts have been used to extract lanthanides from oxides, hydroxides, ores, phosphors, magnets, and waste batteries. Flow-through-type experiments have been useful for measuring extraction kinetics for various lanthanide-containing materials. Equilibrium -type experiments have helped to show the effect of different parameters on phase equilibria, often making use of spectroscopy to measure supercritical lanthanide concentrations in situ. Several studies have noted that extraction decreases when more water is added to the system; this is likely due to the condensation of aqueous droplets, which segregate lanthanides and thus inhibit extraction. It is proposed that varying degrees of water dissolution account for the inconsistent effect of pressure or temperature on extraction across various studies.

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Competitive complexation of solid lanthanide nitrates with tri-n-butyl phosphate in n-hexane

Cited by 7 publications

References 19 publications

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

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

Preliminary Result from the Dissolution of Neodymium and Erbium Oxide in a Tributyl Phosphate Solvent

Supercritical Extraction of Lanthanide Tributyl Phosphate Complexes: Current Status and Future Directions

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