PECULIARITIES OF CATHODIC REDUCTION OF RHENIUM(VII) IN ALKALINE ELECTROLYTES

Autor: Svetlana V. Kovaleva, Irina A. Shabanova, Andrey V. Korshunov
Jazyk: ruština
Rok vydání: 2019
Předmět:
Zdroj: Известия Томского политехнического университета: Инжиниринг георесурсов, Vol 330, Iss 3, Pp 163-174 (2019)
Druh dokumentu: article
ISSN: 24131830
2500-1019
2413-1830
DOI: 10.18799/24131830/2019/3/175
Popis: Relevance. Rhenium and its alloys are refractory, heat-resistant, high-temperature, and corrosion-resistant materials which are used in aircraft and rocket engineering, electrical engineering, in production of catalysts. Rhenium belongs to rare elements, this necessitates the improvement of technological processes for its extraction from natural raw materials and waste materials, as well as improving the accuracy of analytical methods for its determination. Electrochemical methods are optimal in terms of cost, expressiveness and availability for analysis and processing of rhenium-containing raw materials. In this regard, the study of the regularities of the electrode processes involving rhenium and its compounds is relevant. The aim of the research is to establish the sequence of cathodic reduction of perrhenate ions in alkaline electrolytes. Objects: ammonium perrhenate solutions, sodium hydroxide solutions. Methods: direct and alternating current polarography, cyclic voltammetry, accumulative potentiostatic electrolysis. Results. The authors have determined the interval of potentials of cathodic reduction of ReO4– ions (1×10–5…1×10–2 М) in alkaline medium (1...10 M NaOH) at mercury electrodes is –1,25…–1,75 V (sat. Ag/AgCl/KCl). A significant contribution of catalytic and adsorption current components to the total value of cathodic current was established on the basis of temperature dependence of limiting current and current dependence on height of dropping Hg-electrode column. A sequence for reduction of ReO4– in alkaline electrolytes was established using cyclic voltammetry, and a scheme of the cathodic process was proposed which includes electrode, chemical and adsorption stages. Experimental data on potentiostatic electrolysis and on voltammetry of chemically synthesized ReO2 were used to interpret the polarographic results. The paper demonstrates the importance of the obtained results for analytical determination of rhenium.
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