The Role of Chlorine Dioxide in the Electroreduction of Chlorates at Low pH

• Published in: Russian journal of electrochemistry Vol. 58; no. 11; pp. 978 - 988
• Main Authors: Konev, D. V., Goncharova, O. A., Tolmachev, Yu. V., Vorotyntsev, M. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-11-2022; Springer Nature B.V
• Subjects: Aqueous solutions; Chemistry; Chemistry and Materials Science; Chlorates; Chlorine; Chlorine dioxide; Electrochemistry; Electrolysis; Electrowinning; Physical Chemistry; Sulfuric acid; redox-mediator process; chlorate reduction; multielectron oxidizers; redox flow batteries; autocatalysis
• ISSN: 1023-1935; 1608-3342
• DOI: 10.1134/S1023193522110088

The specific features of the electroreduction of chlorates in strongly acidic aqueous solutions are studied by carrying out the electrolysis of 12.5 mM solution of sodium chlorate in 8 M sulfuric acid under potentiostatic conditions at the limiting cathodic current. The periodically collected optical spectrum of solution reveals the main contribution made by chlorine dioxide ClO
2
. It is shown that both the current and the chlorine dioxide concentration vary in time by one and the same law corresponding to the autocatalytic redox-mediator mechanism. When the current passes through a sharp maximum typical of this mechanism, a considerable part of the total concentration of chlorine atoms in the system pertains to chlorine dioxide; hence, this component plays the key role in the process of chlorate electroreduction. The virtually complete conversion of initial chlorate to chloride is observed.