Solubility of niobium(V) and tantalum(V) under mild alkaline conditions

Deblonde, Gauthier J.‐P.; Chagnes, Alexandre; Bélair, Sarah; Cote, Gérard

doi:10.1016/j.hydromet.2015.05.015

Cited by 53 publications

(42 citation statements)

References 29 publications

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“…[28][29][30] Solubility and ion-pairing was used to separate ppm levels of Cs from nuclear wastes containing 3 moles of Na -sodium tetraphenylborate is soluble while Cs tetraphenylborate is insoluble. 23 Despite the similarities between {Nb 6 } and {Ta 6 } in the solid state, we and others have noted considerable differences in solution behavior, [33][34][35][36] but the fundamental origin of these differences has never been explained, other than inference to broadly defined effects of frontier f-orbitals present in {Ta 6 } but not {Nb 6 }. Next to Zr and Hf, Nb and Ta are the two elements on the Periodic table that are the most chemically similar as a direct consequence of the lanthanide effect.…”

Section: Introductionmentioning

confidence: 56%

Electronic and relativistic contributions to ion-pairing in polyoxometalate model systems

Sures

Serapian

Kozma

et al. 2017

Phys. Chem. Chem. Phys.

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Ion pairs and solubility related to ion-pairing in water influence many processes in nature and in synthesis including efficient drug delivery, contaminant transport in the environment, and self-assembly of materials in water. Ion pairs are difficult to observe spectroscopically because they generally do not persist unless extreme solution conditions are applied. Here we demonstrate two advanced techniques coupled with computational studies that quantify the persistence of ion-pairs in simple solutions and offer explanations for observed solubility trends. The system of study, (TMA,Cs)

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Section: Introductionmentioning

confidence: 56%

Electronic and relativistic contributions to ion-pairing in polyoxometalate model systems

Sures

Serapian

Kozma

et al. 2017

Phys. Chem. Chem. Phys.

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“…For the higher NaOH concentrations, however, the reaction of Ta 3 N 5 with the aqueous solution becomes significant resulting in NH 3 release . Consequently, nitrogen concentration in the precipitates would be suppressed.…”

Section: Resultsmentioning

confidence: 95%

“…For the higher NaOH concentrations, however, the reaction of Ta 3 N 5 with the aqueous solution becomes significant resulting in NH 3 release. 19 Consequently, nitrogen concentration in the precipitates would be suppressed. Focusing on the difference in the amount of NaOH aqueous solution, we found that as the water is less in the hydrothermal condition, doped nitrogen in NaTaO 3-x N y increased.…”

Section: Photocatalytic Activity Testmentioning

confidence: 99%

Control of nitrogen doping in NaTaO₃ synthesized by hydrothermal reaction and chemical state of nitrogen

Ozawa

Kobayashi

Yoshida

2018

Surface & Interface Analysis

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Nitrogen‐doped NaTaO3 was synthesized through 1‐pot reaction, hydrothermal process using Ta3N5 as precursor. Changing concentration and amount of NaOH aqueous solution influenced nitrogen content in NaTaO3. Absorption edge of nitrogen‐doped NaTaO3 was extended at 570 nm, and absorbance in visible light region depended on nitrogen content in NaTaO3. Anodic photocurrent measured under visible light irradiation became larger with increasing nitrogen content in NaTaO3‐xNy. Under ultraviolet light irradiation (λ ≤ 400 nm), the highest anodic photocurrent was observed when nitrogen concentration was y = 0.024. It was possible to expand the wavelength range that can be effectively utilized for the photoelectrochemical reaction.

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“…x−8 ions are the temperature, the ionic strength and the nature of the alkaline [27][28][29]). Temperature and ionic strength are continuous factors whereas counter-ion nature is not.…”

Section: Choice Of the Factors Variation Domains And Responsesmentioning

confidence: 99%

Development of a capillary electrophoresis method for the analysis in alkaline media as polyoxoanions of two strategic metals: Niobium and tantalum

Deblonde

Chagnes

Cote

et al. 2016

Journal of Chromatography A

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Tantalum (Ta) and niobium (Nb) are two strategic metals essential to several key sectors, like the aerospace, gas and oil, nuclear and electronic industries, but their separation is really difficult due to their almost identical chemical properties. Whereas they are currently produced by hydrometallurgical processes using fluoride-based solutions, efforts are being made to develop cleaner processes by replacing the fluoride media by alkaline ones. However, methods to analyze Nb and Ta simultaneously in alkaline samples are lacking. In this work, we developed a capillary zone electrophoresis (CE) method able to separate and quantify Nb and Ta directly in alkaline media. This method takes advantage of the hexaniobate and hexatantalate ions which are naturally formed at pH>9 and absorb in the UV domain. First, the detection conditions, the background electrolyte (BGE) pH, the nature of the BGE co-ion and the internal standard (IS) were optimized by a systematic approach. As the BGE counter-ion nature modified the speciation of both ions, sodium- and lithium-based BGE were tested. For each alkaline cation, the BGE ionic strength and separation temperature were optimized using experimental designs. Since changes in the migration order of IS, Nb and Ta were observed within the experimental domain, the resolution was not a monotonic function of ionic strength and separation temperature. This forced us to develop an original data treatment for the prediction of the optimum separation conditions. Depending on the consideration of either peak widths or peak symmetries, with or without additional robustness constraints, four optima were predicted for each tested alkaline cation. The eight predicted optima were tested experimentally and the best experimental optimum was selected considering analysis time, resolution and robustness. The best separation was obtained at 31.0°C and in a BGE containing 10mM LiOH and 35mM LiCH3COO.The separation voltage was finally optimized, resulting in the separation of Nb, Ta, and IS in less than 2.5min, which is three times faster than any CE method ever reported for the separation of Nb and Ta (acidic media included). Some figures of merit of the method were determined such as linearity ranges and limits of quantitation. Finally, the method was successfully applied to the analysis of a real industrial sample.

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Solubility of niobium(V) and tantalum(V) under mild alkaline conditions

Cited by 53 publications

References 29 publications

Electronic and relativistic contributions to ion-pairing in polyoxometalate model systems

Electronic and relativistic contributions to ion-pairing in polyoxometalate model systems

Control of nitrogen doping in NaTaO₃ synthesized by hydrothermal reaction and chemical state of nitrogen

Development of a capillary electrophoresis method for the analysis in alkaline media as polyoxoanions of two strategic metals: Niobium and tantalum

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Solubility of niobium(V) and tantalum(V) under mild alkaline conditions

Cited by 53 publications

References 29 publications

Electronic and relativistic contributions to ion-pairing in polyoxometalate model systems

Electronic and relativistic contributions to ion-pairing in polyoxometalate model systems

Control of nitrogen doping in NaTaO3 synthesized by hydrothermal reaction and chemical state of nitrogen

Development of a capillary electrophoresis method for the analysis in alkaline media as polyoxoanions of two strategic metals: Niobium and tantalum

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Control of nitrogen doping in NaTaO₃ synthesized by hydrothermal reaction and chemical state of nitrogen