Remarkably High Separation of Neodymium from Praseodymium by Selective Dissolution from their Oxide Mixture using an Ionic Liquid Containing aβ‐Diketone

Sengupta, Arijit; Goyal, Priya; Prava Mantry, Swarna; Sundararajan, Mahesh; Kumar Verma, Parveen; Kumar Mohapatra, Prasanta

doi:10.1002/chem.202303923

Cited by 4 publications

(2 citation statements)

References 63 publications

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“…Thin-layer oil film extraction was also reported to have enhanced the mutual separation (β Pr/Nd ∼ 10). 26 In our earlier report, a mutual separation of Nd/Pr by selective dissolution in an ionic liquid containing HTTA (2thenoyltrifluoroacetone) as a ligand resulted in a separation factor of ∼598, 7 which is significantly lower than the maximum separation factor value achieved in the present investigation (β Nd/Pr ∼ 700), using HFAA as the β-diketone ligand (instead of HTTA). Moreover, to achieve the maximum β value for HTTA, ∼10 h of dissolution was required, whereas in the present case, only 15 min were sufficient to achieve the same.…”

Section: ■ Introductioncontrasting

confidence: 68%

“…Hence, the separation factor (expressed as the ratio of the distribution ratio or D values) was found to be within 2− 10. To achieve significantly higher separation factor values, a novel methodology has been proposed for the selective dissolution of Nd into the ionic liquid phase directly from the mixtures of their oxides (Nd 2 O 3 and Pr 6 O 11 ), utilizing the difference in their lattice energy of formation values (−34.13 eV for Nd 2 O 3 and −76.29 eV for Pr 6 O 11 ) 7 and thereby avoiding the cumbersome dissolution process. HFAA, a βdiketone, has been used in the ionic liquid C 4 mim.NTf 2 for the controlled release of H + from its enol form arising out of the keto−enol tautomerism.…”

Section: ■ Introductionmentioning

confidence: 99%

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Unprecedented Mutual Separation of Nd–Pr by Selective Dissolution of Nd₂O₃ Directly from a Nd₂O₃–Pr₆O₁₁ Mixture into an Ionic Liquid Containing a Highly Fluorinated β-Diketone

Nair,

Bhat,

Goyal

et al. 2024

Ind. Eng. Chem. Res.

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An unprecedented mutual separation between neodymium (Nd) and praseodymium (Pr) has been achieved with a maximum separation factor of 700, which is more than 350 times better than the conventional hydrometallurgical method by selective dissolution of hexagonal Nd 2 O 3 directly for a physical mixture of Nd 2 O 3 and Pr 6 O 11 into an ionic liquid (C 4 mim.NTf 2 ) phase containing a fluorinated β-diketone, hexafluoroacetylacetone (HFAA), within 15 min of the dissolution process (leaving cubic Pr 6 O 11 as an undissolved solid residue). The selectivity was induced from the differences in the respective lattice energies of Nd 2 O 3 and Pr 6 O 11 in synergy with the controlled release of H + by HFAA into the ionic liquid and subsequent stabilization of Nd 3+ by complexation with the enolate form of HFAA arising out of the keto−enol tautomerism of the β-diketone. The initial sintering of the precursor oxides was found to be mandatory for the removal of the protective hydroxide layer of Nd on an aged Nd 2 O 3 sample. The water content in the ionic liquid, the concentration of HFAA, the solid-to-liquid ratio, stirring (or mixing) time, the relative composition of the Nd 2 O 3 −Pr 6 O 11 mixture, dissolution temperature, etc., strongly influenced the dissolution characteristics and hence the separation efficiency. Nd dissolution was found to be exothermic, as also evident from calorimetric measurements, indicating an enhancement in temperature with an enthalpy of dissolution (ΔH) of ∼24.66 J/g.

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Section: ■ Introductioncontrasting

confidence: 68%

Section: ■ Introductionmentioning

confidence: 99%

Unprecedented Mutual Separation of Nd–Pr by Selective Dissolution of Nd₂O₃ Directly from a Nd₂O₃–Pr₆O₁₁ Mixture into an Ionic Liquid Containing a Highly Fluorinated β-Diketone

Nair,

Bhat,

Goyal

et al. 2024

Ind. Eng. Chem. Res.

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Effect of Structural Modification in β Diketone on the Mutual Separation of Nd and Pr into Room-Temperature Ionic Liquid

Bhat,

Goyal,

Nair

et al. 2024

Ind. Eng. Chem. Res.

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A novel approach for mutual separation between Nd and Pr has been demonstrated by the selective dissolution of Nd2O3 into an ionic liquid (C4mim·NTf2) containing two β diketones, viz., acetyl trifluoroacetone (ATA) and benzoyl trifluoroacetone (BTA), directly from a physical mixture of their most stable oxides, i.e., Nd2O3 and Pr6O11, avoiding their cumbersome aqueous phase dissolution and the subsequent aqueous phase chemistry. The controlled release of the H+ ion by the β diketones to form the enolate conformation has been used to hold the dissolved Nd3+ ion in the ionic liquid phase as Nd (enolate of β diketone)4 – species. The selective dissolution of Nd2O3 over Pr6O11 can be achieved by utilizing one of the prime driving forces of their difference in lattice energy of formation (U Nd2O3 ∼ −3292.86 kJ/mol and U Pr6O11 ∼ −7360.45 kJ/mol, respectively). The extent of dissolution was found to be greater with BTA for both Nd and Pr as compared to that seen with ATA. However, the selectivity was much better with ATA. A maximum separation factor of βNd/Pr ∼ 217 was achieved using 0.1 M ATA in C4mim·NTf2 containing 1.5% water for 15 min of biphasic equilibration with a solid-to-liquid ratio of 5.33 g L–1 from the physical mixture of Nd2O3/Pr6O11 ∼ 2:1. The separation factor, reported in this study, was found to be more than 100 times better than that reported for the conventional route of hydrometallurgical separation. The exothermic nature of Nd dissolution was evidenced from the calorimetric experiments, with the estimated enthalpy of dissolution for ATA and BTA being −169.23 and −126.46 J/g, respectively. The subsequent quantitative back extraction of Nd by 0.5 M HNO3 provides the opportunity for recycling of the ionic liquid for subsequent dissolution. The effects of water content, ATA/BTA concentration, relative ratio for Nd2O3/Pr6O11, dissolution temperature, etc., have been studied to understand their separation characteristic and hence to achieve the best mutual separation of the two rare earth metal ions.

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Complexation of Trivalent Lanthanides with Hexaalkyl Nitrilotriacetamides into Methylimidazolium-Based Ionic Liquids: Spectroscopic, Electrochemical, Calorimetric, and Theoretical Insights

Goyal,

Srivastava,

Sengupta

et al. 2024

Inorg. Chem.

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Exothermic, spontaneous inner-sphere complexation of trivalent lanthanides with N,N,N′,N′,N″,N″-hexaalkyl-substituted nitrilotriacetamides (HRNTAs) into 1-hexyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (C 6 mim NTf 2 ) is reported with a predominant presence of ML and ML 2 complexes having complexation constants, β 1 Eu 3.10 ± 0.02 ,β 1 Nd 2.67 ± 0.03 and β 2 Eu 5.22 ± 0.04, β 2 Nd 4.95 ± 0.02, respectively, for the n-butyl-substituted HRNTA (HBNTA); while those for the n-hexyl derivative (HHNTA) are β 1 Eu 4.27 ± 0.03, β 1 Nd 3.71 ± 0.03 and β 2 Eu 7.70 ± 0.03, β 2 Nd 7.18 ± 0.04, respectively. HHNTA shows better complexing ability; whereas the stronger complexation of the Nd 3+ over Eu 3+ is attributed to the lanthanide contraction. Furthermore, the nature of the ionic liquid also influences the extent of complexation with the trend: C 4 mim NTf 2 > C 6 mim NTf 2 > C 8 mim NTf 2 , which follows the order of their dielectric constants. Judd− Ofelt parameters were calculated from photoluminescence data to get an idea about the symmetry of the Eu 3+ complexes. Electrochemical investigations give diffusion coefficient values of 1.17 × 10 −7 and 8.26 × 10 −8 cm 2 /s for the Eu 3+ complexes of HBNTA and HHNTA, respectively. Changes in the spectral characteristics and peak positions are evidenced in the FTIR spectra on the complexation of Eu 3+ with the HRNTA ligands in C 6 mim NTf 2 . Structure optimization for the complexes was performed by DFT computations.

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Remarkably High Separation of Neodymium from Praseodymium by Selective Dissolution from their Oxide Mixture using an Ionic Liquid Containing aβ‐Diketone

Cited by 4 publications

References 63 publications

Unprecedented Mutual Separation of Nd–Pr by Selective Dissolution of Nd₂O₃ Directly from a Nd₂O₃–Pr₆O₁₁ Mixture into an Ionic Liquid Containing a Highly Fluorinated β-Diketone

Unprecedented Mutual Separation of Nd–Pr by Selective Dissolution of Nd₂O₃ Directly from a Nd₂O₃–Pr₆O₁₁ Mixture into an Ionic Liquid Containing a Highly Fluorinated β-Diketone

Effect of Structural Modification in β Diketone on the Mutual Separation of Nd and Pr into Room-Temperature Ionic Liquid

Complexation of Trivalent Lanthanides with Hexaalkyl Nitrilotriacetamides into Methylimidazolium-Based Ionic Liquids: Spectroscopic, Electrochemical, Calorimetric, and Theoretical Insights

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Remarkably High Separation of Neodymium from Praseodymium by Selective Dissolution from their Oxide Mixture using an Ionic Liquid Containing aβ‐Diketone

Cited by 4 publications

References 63 publications

Unprecedented Mutual Separation of Nd–Pr by Selective Dissolution of Nd2O3 Directly from a Nd2O3–Pr6O11 Mixture into an Ionic Liquid Containing a Highly Fluorinated β-Diketone

Unprecedented Mutual Separation of Nd–Pr by Selective Dissolution of Nd2O3 Directly from a Nd2O3–Pr6O11 Mixture into an Ionic Liquid Containing a Highly Fluorinated β-Diketone

Effect of Structural Modification in β Diketone on the Mutual Separation of Nd and Pr into Room-Temperature Ionic Liquid

Complexation of Trivalent Lanthanides with Hexaalkyl Nitrilotriacetamides into Methylimidazolium-Based Ionic Liquids: Spectroscopic, Electrochemical, Calorimetric, and Theoretical Insights

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Unprecedented Mutual Separation of Nd–Pr by Selective Dissolution of Nd₂O₃ Directly from a Nd₂O₃–Pr₆O₁₁ Mixture into an Ionic Liquid Containing a Highly Fluorinated β-Diketone

Unprecedented Mutual Separation of Nd–Pr by Selective Dissolution of Nd₂O₃ Directly from a Nd₂O₃–Pr₆O₁₁ Mixture into an Ionic Liquid Containing a Highly Fluorinated β-Diketone