Purification of rare earth bis(trifluoromethyl-sulfonyl)amide salts by hydrometallurgy and electrodeposition of neodymium metal using potassium bis(trifluoromethyl-sulfonyl)amide melts

Ota, Hisashi; Matsumiya, Masahiko; Yamada, Takahiro; Fujita, Tetsuo; Kawakami, Satoshi

doi:10.1016/j.seppur.2016.06.044

Cited by 17 publications

(7 citation statements)

References 21 publications

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confidence: 55%

“…The absence of the oxidation processes demonstrates that it is an irreversible process, as has been reported in the literature for different lanthanides in ionic liquids and organic solventbased electrolytes. 37,[40][41][42][43]50,53,54 The current density of the second cathodic process (C2) became more significant with current densities up to −1.97 mA cm −2 with increasing salt concentration up to 0.35 mol kg −1 . However, a more in-depth study would be necessary to confirm the nature of such processes, C1 and C2.…”

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confidence: 99%

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Water-Facilitated Electrodeposition of Neodymium in a Phosphonium-Based Ionic Liquid

Sanchez-Cupido

Pringle

Siriwardana

et al. 2019

J. Phys. Chem. Lett.

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Rare-earth metals are considered critical metals due to their extensive use in energy-related applications such as wind turbines and nickel−metal hybrid batteries found in hybrid electrical vehicles. A key drawback of the current processing methods includes the generation of large amounts of toxic and radioactive waste. Thus the efficient recovery of these valuable metals as well as cleaner processing methods are becoming increasingly important.Here we report on a clean electrochemical route for neodymium (Nd) recovery from [P 6,6,6,14 ][TFSI], trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)amide which is amplified three times by the presence of water, as evidenced by the cathodic current density and thicker deposits. The role of Nd salt concentrations and water content as an additive in the electrochemistry of Nd 3+ in [P 6,6,6,14 ][TFSI] has been studied. The presence of metallic neodymium in the deposits has been confirmed by X-ray photoelectron spectroscopy.

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confidence: 55%

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confidence: 99%

Water-Facilitated Electrodeposition of Neodymium in a Phosphonium-Based Ionic Liquid

Sanchez-Cupido

Pringle

Siriwardana

et al. 2019

J. Phys. Chem. Lett.

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“…Various electrochemical processes, such as redox reactions with reduced and oxidised species present in the same phase [6,14,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35], adsorption on surfaces of electrodes [36][37][38], electrodeposition [39][40][41][42][43][44][45][46][47][48] or electrodissolution [49][50][51] were analysed by means of semi-differentiation or semi-integration. The most extensive mathematical treatment related to these methods was applied to the electrochemical reactions were both oxidised and reduced form are soluble in the electrolyte phase and their transport proceeds under conditions of semi-infinite linear diffusion [4].…”

Section: Introductionmentioning

confidence: 99%

Semi-differential analysis of irreversible voltammetric peaks

Grdeń

2016

J Solid State Electrochem

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Voltammetric peaks obtained by simulation of electrochemical reactions under conditions of linear semi-infinite diffusion with an irreversible electron transfer process are analysed using a semi-differentiation procedure. Obtained semi-derivative peaks, separated or overlapped, are fitted with appropriate mathematical functions. The functions used for data fitting include a function describing symmetrical peaks, proposed by several authors for fitting irreversible semiderivative peaks, and two alternative functions that express asymmetric shape of the irreversible semi-derivative signals. When applied to the overlapped irreversible semi-derivative peaks, the latter two functions allow calculating certain electrochemical parameters with a better accuracy as compared with the function derived for the symmetrical peaks.

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“…In this analysis, Dy surface composition was determined using EDS characterization. The reported REE compositions in obtained electrodeposits from ionic liquids range from 10 to 75%, ,,,,, mostly based on surface analysis by EDS. Elemental compositions from EDS analysis in the electrodeposited films are displayed in Figure c,d.…”

Section: Resultsmentioning

confidence: 99%

Water Interplays during Dysprosium Electrodeposition in Pyrrolidinium Ionic Liquid: Deconvoluting the Pros and Cons for Rare Earth Metallization

Orme

Baek

Fox

et al. 2021

ACS Sustainable Chem. Eng.

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The electrochemical production of rare earth metals (REMs) in ionic liquids (ILs) has received much attention as a promising, sustainable replacement to molten salt electrolysis. Water additives have been suggested as a promoting strategy for the ionic liquid process; however, the fundamental understanding of the interfacial processes required to assess the overall viability for REM production is lacking. In this regard, a full investigation of the impact of water on dysprosium (Dy) electrodeposition in pyrrolidinium triflate (BMPyOTf) ionic liquid was carried out. Water introduction was revealed to involve an interplay of implications on the electrodeposition process, including coordination, speciation, reduction pathways, interfacial dynamics, nucleation, and metal stability and purity. Under highly dry conditions, the reduction occurs at a very negative potential (−3.3 V) in a consecutive pathway, resulting in negligible metal electrodeposition (low rate and efficiency) at the electrode surface. Small water concentrations (<500 ppm) lead to partitioning of the Dy complex between water and IL-coordinated speciation, giving rise to an additional wave at a more positive potential (−2.4 V). Probing the heterogeneous Dy speciation by spectroscopic analyses enabled uncovering of the reduction mechanism and evaluation of the mass transport properties. In addition to lowering the reduction thermodynamics, water introduction also improved the nucleation, deposition rate, and faradic efficiency. Despite these benefits, stripping voltammetric analysis predicts substantial chemical reactivity of the deposited Dy metal with water additives and/or electrolyte components, under long timescales. Surface characterization of the obtained product confirmed the instability of Dy metal as an oxidized/fluorinated material and its limited purity (∼60%). Moreover, high water introduction triggered a fast hydrogen evolution reaction (HER), downgrading the robustness of system efficiency. The overall impact of water additives seems to engender both promoting and mitigating effects on electrochemical REM production in IL, requiring a specific technoeconomic assessment and/or more innovative strategies to be sought.

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Purification of rare earth bis(trifluoromethyl-sulfonyl)amide salts by hydrometallurgy and electrodeposition of neodymium metal using potassium bis(trifluoromethyl-sulfonyl)amide melts

Cited by 17 publications

References 21 publications

Water-Facilitated Electrodeposition of Neodymium in a Phosphonium-Based Ionic Liquid

Water-Facilitated Electrodeposition of Neodymium in a Phosphonium-Based Ionic Liquid

Semi-differential analysis of irreversible voltammetric peaks

Water Interplays during Dysprosium Electrodeposition in Pyrrolidinium Ionic Liquid: Deconvoluting the Pros and Cons for Rare Earth Metallization

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