Facile electroreduction of perrhenate in weakly acidic citrate and oxalate media

Vajo, John J.; Aikens, D. A.; Ashley, L.; POELTL, D. E.; Bailey, R. A.; Clark, Herbert M.; Bunce, Stanley C.

doi:10.1021/ic50224a037

Cited by 29 publications

(20 citation statements)

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“…Unsuccessful attempts to characterize ReO − 4 -citric acid complexes by UV-Vis absorption spectroscopy were reported before. 11,19 Raman spectroscopy.-Raman spectroscopy was first applied here, to the best of our knowledge, for studying electrolytes for Re-Ni deposition. In order to estimate the effect of simultaneous presence of Ni(SO 3 NH 2 ) 2 and NH 4 ReO 4 in citrate electrolyte on the Raman spectrum, we considered the spectra of citrate solution and of citrate electrolytes containing Ni (SO 3 NH 2 ) 2 and NH 4 ReO 4 separately.…”

Section: Resultsmentioning

confidence: 99%

The Influence of Weak Ionic Interactions on Electrode Reactions during Electrodeposition of Re-Ni Alloys

Berkh

Khatchatouriants

Eliaz

et al. 2014

J. Electrochem. Soc.

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The electroplating of Re-Ni alloys in citrate electrolytes of different compositions was studied by cyclic voltammetry and by anodic stripping voltammetry, following galvanostatic deposition. The faradaic efficiency of the deposition process and the composition of the deposits were determined. Increasing the concentrations of either the nickel or the perrhenate ion in the electrolytes was shown to enhance the rate of deposition of the Re-Ni alloy. The process is influenced by mass transport and by concentration of citric acid in the electrolytes. Conductometry, UV-Vis and Raman spectroscopy were used for studying the ionic interactions in electrolytes. No evidence of the existence of perrhenate complexes with other components of the electrolyte was found. However, an increased deformation of the perrhenate ions with increasing molar ratio of [NiCit] − /ReO − 4 was clearly shown by Raman spectroscopy. Hence, a weak interaction is definitely observed, which is enough to distort the shapes of the ReO − 4 and [NiCit] − or [NiHCit] species, thus enhancing the deposition rate of the Re-Ni alloy. The induced co-deposition is believed to be a catalytic process, including the stage of simultaneous reduction of ReO − 4 and [NiCit] − or [NiHCit] species, which influences each other by weak interaction.Rhenium and its alloys are used for different purposes where stability at high temperatures is important, such as aerospace and nuclear industries, as well as in catalysis, mainly for the petroleum industry. It also has applications as coatings. We have published a detailed listing of its unique properties and applications. 1 Electrodeposition of Re itself is very difficult, and the resulting deposits are usually non-uniform and tend to peel off readily. However, addition of the salts of Ni, Co or Fe catalyzes the deposition of the respective alloys. A typical plating bath consists of ReO − 4 , Ni(SO 3 NH 2 ) 2 and citrate. 2-10 The mechanism of induced co-deposition of Re with one of the above iron-group metals has been studied recently in our research group, 5-8 with emphasis on the role of Me (Me = Ni, Co, or Fe). The composition of the alloy deposited could be controlled by the relative concentration of the three components of the bath, the pH of the solution, the temperature and the current density applied. The highest Re-content achieved was 93 at.% and the highest faradaic efficiency (FE) was 96% in different compositions of the baths in the above publications. A leading role of freshly deposited Ni in catalytic deposition of Re was observed. [5][6][7][8]11 . On the other hand, a simultaneous discharge of Ni and perrhenate ions was shown to be responsible for the increase in the partial current density of the Re deposition. 4 The concept of simultaneous discharge is supported by the active role of perrhenate in nickel co-deposition. In fact, no Ni is deposited from the Ni electrolytes with high citrate to Ni 2+ molar ratio (of about 4.2), 12 while about 20 at.% Ni is found in the deposits produced in electrolytes with t...

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Section: Resultsmentioning

confidence: 99%

The Influence of Weak Ionic Interactions on Electrode Reactions during Electrodeposition of Re-Ni Alloys

Berkh

Khatchatouriants

Eliaz

et al. 2014

J. Electrochem. Soc.

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“…Considering the perrhenate-citrate complex [ReO 4 H 2 Cit] 2− , its dissociation rate was found to be independent of pH in the range of 3.0-5.5, but increased rapidly with decreasing pH below 3.0, approaching a first-order dependency at pH = 2.0. 33 We thus hypothesize that this complex being less stable at pH 2.0 or 2.5 allowed efficient plating of the alloy, which resulted in an increase in the Re-content and, correspondingly, low FE.…”

Section: Resultsmentioning

confidence: 96%

“…It is well known that the variation of pH in citrate-containing perrhenate (and other) electroplating baths results in the formation of different metal-citrate complexes, which is expected to have an impact on the overall electroplating process and the nature of the deposits. [31][32][33] The temperature of the electrolytes is another important parameter in electroplating of Re-based alloys.…”

Section: -28mentioning

confidence: 99%

The Effects of pH and Temperature on Electrodeposition of Re-Ir-Ni Coatings from Aqueous Solutions

Eliaz

Gileadi

2014

J. Electrochem. Soc.

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The Re-Ir system is of great interest for high-temperature applications and extreme environments. Here, Re-Ir-Ni alloy coatings were electroplated from aqueous solutions. The effects of pH and temperature on the faradaic efficiency (FE), chemical composition, surface morphology and crystallographic structure of the coatings were studied. The results show that the pH and temperature of electrolytes have a significant effect on the electrodeposition of Re-Ir-Ni. As the pH was increased from 2.0 to 8.0, the FE, partial current densities for deposition of the three metals, and deposition rate increased. The highest Re-content (82 at%) was obtained at pH = 2.5. At pH = 2.0, the coating consisted of an amorphous phase, and no cracking was observed. When raising the pH to 4.0 and above, crystalline phases (including hydrides) formed, and both columnar crystals and micro-cracks were observed. The bath temperature affected the surface crack density and the size of the grains that form the mesoscopic colonies. At the two lowest temperatures studied herein (50 and 60 • C), no codeposition of Ir was observed. The phase composition of the coating changed from amorphous Re-Ni at 50 • C; to amorphous Re-Ni, hcp-Ni and hexagonal Pure rhenium (Re) has high melting point (3,186• C), excellent wear resistance, and superior strength and ductility at elevated temperatures. In addition, it does not suffer from ductile-to-brittle transition, and it does not form carbides while having good mutual wettability with carbon. 1,2At present, the main manufacturing processes of Re and its alloys are powder metallurgy and chemical vapor deposition (CVD). 1-3In recent years, we have studied electroplating 4-12 and electroless plating 13,14 as alternative processes. Electrodeposition of pure Re was found to have a low faradaic efficiency (FE) and poor quality.4 Addition of iron-group metal salts to the plating bath results in the formation of Re-Me alloys (Me = Ni, Co or Fe) with high Re-content and at high FE, thus showing a catalytic effect of the iron-group metals on the electrodeposition of Re. 5,7 Rhenium and its alloys with iron-group metals tend to oxidize readily in moist air at temperatures above 600• C. 1,2 In order to protect them from high-temperature oxidation, a top coating such as rhodium (Rh) or iridium (Ir) is often applied. Iridium has high melting point (2,446• C) and excellent corrosion resistance. 15,16 Re and Ir show extensive mutual solubility and no intermetallic compounds in their binary phase diagram. Iridium can also act as an effective diffusion barrier for inward-diffusing oxygen and outward-diffusing carbon. It is thus one of the most promising candidates for protective coating of either structural carbons or Re-based components for extreme environments.2,17,18 Iridium-coated Re nozzles are used in aerospace applications for small chemical rockets and resistojet thrusters.19 A combustion chamber composed of Re substrate and Ir coating has been demonstrated to be stable for extended lifetimes at temperatures as high ...

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“…It is reported that oxalate and citrate in weakly acidic medium markedly increase the ease of reduction of ReO 4 − through formation of 1 : 1 complex [28]. Oxalic acid was chosen in our studies to avoid organic residues in the electrolyte solution or adsorbed on the 188 Re deposited on the electrode, which could potentially affect the subsequent labeling of 188 Re for radiopharmaceutical applications.…”

Section: Electrochemical Separation Of 188 Re From a 188 W/ 188 Re MImentioning

confidence: 99%

A novel 188W/188Re electrochemical generator with potential for medical applications

Chakravarty¹,

Dash²,

Kothari³

et al. 2009

Radiochimica Acta

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Rhenium-188 is a well recognized therapeutic radionuclide and its use in a variety of applications has been reported. The current methods of obtaining "no-carrier added" 188 Re from conventional alumina based generators require 188 W of very high specific activity for obtaining reasonable quantities of 188 Re in an adequately concentrated form. We have developed a simple electrochemical separation technique adaptable for using low specific activity 188 W, for the separation of 188 Re from 188 W, and obtain 188 Re amenable for radiolabeling biomolecules. The overall decay corrected yield of 188 Re was > 70%. The recovered 188 Re had high radiochemical (> 97%) and radionuclidic purity (> 99.99%). The suitability of the 188 Re for radiolabeling was demonstrated by its use for the complexation of DMSA and HEDP with labeling yields > 98%. Repeated separation of 188 Re from a stock solution of 188 W could be demonstrated for a period of 70 d. The preliminary results suggest that the process can be scaled up to higher activity levels and suggest that this strategy can be further explored for the development of electrolytic type 188 W/ 188 Re generator suitable for clinical applications.

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Facile electroreduction of perrhenate in weakly acidic citrate and oxalate media

Cited by 29 publications

References 0 publications

The Influence of Weak Ionic Interactions on Electrode Reactions during Electrodeposition of Re-Ni Alloys

The Influence of Weak Ionic Interactions on Electrode Reactions during Electrodeposition of Re-Ni Alloys

The Effects of pH and Temperature on Electrodeposition of Re-Ir-Ni Coatings from Aqueous Solutions

A novel 188W/188Re electrochemical generator with potential for medical applications

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