Electrodeposition of Rhenium Species at a Stainless Steel Electrode from Acidic, Neutral, and Alkaline Solutions

Abstract

The mechanism of electrochemical reactions of rhenium species at stainless steel 316 electrodes and the effect of the pH in 0.5 M (NH 4 ) 2 SO 4 solutions containing 5 mM HReO 4 (pH 1, 3, and 10) were investigated by electrochemical measurements and surface analyzes of the rhenium-deposited electrodes. From the results of cyclic voltammetry, we found that ReO 4 − anion was electrochemically active and the electrodeposition of rhenium species was accelerated after hydrogen evolution occurred, whereas ReO 4− anion was inactive before hydrogen evolution occurred. This indicates that adsorbed hydrogen atom on the electrodes is needed to reduce ReO 4 − anion. The deposits obtained by potentiostatic electrolysis at a potential lower than that of the hydrogen evolution reaction were analyzed by XPS and SEM. In the pH 1 solution, the deposit was metallic Re, whereas in the pH 3 and 10 solutions, the deposit was a mixture of metallic Re, ReO 2 , and ReO 3 . From the results of anode stripping voltammetry, it was found that the metallic Re was oxidized to ReO 4 − via ReO 3 or ReO 2 .

Review: Rhenium and its smelting and recycling technologies

“…Re metal is electrodeposited onto the cathode in an electrolysis bath containing this eluate and H 2 SO 4 . 47,290 Cementation. When a powder of Zn or Fe metal is immersed in an aqueous solution containing ReO 4 − , Re metal and/or its oxides are deposited on the surface of the metal powder, which acts as a reducing agent to reduce the ReO 4 − through a substitution reaction (cementation).…”

“…Through the addition of a reducing agent such as FeSO 4 or FeCl 2 to the Re-containing aqueous solution and the adjustment of pH to above 7, ReO 4 − can be reduced to ReO 2 or ReO 3 and coprecipitated with Fe(OH) 3 . 268…”

“…Re metal is electrodeposited onto the cathode in an electrolysis bath containing this eluate and H 2 SO 4 . 47,290…”

Electrochemical Study of Metallic Rhenium in Methanol Acidic Aqueous Solutions

“…Posteriorly, in sweeps in the anodic direction these deposited materials formed oxides of high oxidation state, such as Re(VI) or Re(VII) oxides. Rhenium metal is electrodeposited at potentials more negative than 0 V (9)(10)12,15,20,22,(26)(27). However, it is widely accepted that the surface contains Re(0) and oxides of the metal with high oxidation states (22,30).…”

Communication—A Mechanistic Study on Electrodeposition of Rhenium from Acidic Solution of Ammonium Perrhenate

“…5,6 In addition, some attempts using electrodeposition method to prepare metallic rhenium from aqueous solutions have been tried by some groups. [7][8][9] Although the electrodeposition method has shown many advantages, such as low cost and mild preparation condition, direct acquirement of metallic rhenium by this method still remains many challenges. For example, ReO 2 , instead of metallic rhenium, is usually formed in diluted H 2 SO 4 solutions and when the concentration of H 2 SO 4 is more than 10 mol L −1 the product becomes Re 2 O 5 .…”