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Konev DV, Zader PA, Vorotyntsev MA. Evolution of the Bromate Electrolyte Composition in the Course of Its Electroreduction inside a Membrane-Electrode Assembly with a Proton-Exchange Membrane. Int J Mol Sci 2023; 24:15297. [PMID: 37894976 PMCID: PMC10607049 DOI: 10.3390/ijms242015297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 10/07/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023] Open
Abstract
The passage of cathodic current through the acidized aqueous bromate solution (catholyte) leads to a negative shift of the average oxidation degree of Br atoms. It means a distribution of Br-containing species in various oxidation states between -1 and +5, which are mutually transformed via numerous protonation/deprotonation, chemical, and redox/electrochemical steps. This process is also accompanied by the change in the proton (H+) concentration, both due to the participation of H+ ions in these steps and due to the H+ flux through the cation-exchange membrane separating the cathodic and anodic compartments. Variations of the composition of the catholyte concentrations of all these components has been analyzed for various initial concentrations of sulfuric acid, cA0 (0.015-0.3 M), and two values of the total concentrations of Br atoms inside the system, ctot (0.1 or 1.0 M of Br atoms), as functions of the average Br-atom oxidation degree, x, under the condition of the thermodynamic equilibrium of the above transformations. It is shown that during the exhaustion of the redox capacity of the catholyte (x pass from 5 to -1), the pH value passes through a maximum. Its height and the corresponding average oxidation state of bromine atoms depend on the initial bromate/acid ratio. The constructed algorithm can be used to select the initial acid content in the bromate catholyte, which is optimal from the point of view of preventing the formation of liquid bromine at the maximum content of electroactive compounds.
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Affiliation(s)
- Dmitry V. Konev
- Federal Research Center for Problems of Chemical Physics and Medicinal Chemistry of the Russian Academy of Sciences, Chernogolovka 142432, Russia
- Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, Moscow 119071, Russia
| | - Pavel A. Zader
- Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, Moscow 119071, Russia
| | - Mikhail A. Vorotyntsev
- Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, Moscow 119071, Russia
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Kartashova NV, Konev DV, Loktionov PA, Glazkov AT, Goncharova OA, Petrov MM, Antipov AE, Vorotyntsev MA. A Hydrogen-Bromate Flow Battery as a Rechargeable Chemical Power Source. MEMBRANES 2022; 12:1228. [PMID: 36557135 PMCID: PMC9782483 DOI: 10.3390/membranes12121228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/25/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
The hydrogen-bromate flow battery represents one of the promising variants for hybrid power sources. Its membrane-electrode assembly (MEA) combines a hydrogen gas diffusion anode and a porous flow-through cathode where bromate reduction takes place from its acidized aqueous solution: BrO3− + 6 H+ + 6 e− = Br− + 3 H2O (*). The process of electric current generation occurs on the basis of the overall reaction: 3 H2 + BrO3− = Br− + 3 H2O (**), which has been studied in previous publications. Until this work, it has been unknown whether this device is able to function as a rechargeable power source. This means that the bromide anion, Br−, should be electrooxidized into the bromate anion, BrO3−, in the course of the charging stage inside the same cell under strongly acidic conditions, while until now this process has only been carried out in neutral or alkaline solutions with specially designed anode materials. In this study, we have demonstrated that processes (*) and (**) can be performed in a cyclic manner, i.e., as a series of charge and discharge stages with the use of MEA: H2, Freidenberg H23C8 Pt-C/GP-IEM 103/Sigracet 39AA, HBr + H2SO4; square cross-section of 4 cm2 surface area, under an alternating galvanostatic mode at a current density of 75 mA/cm2. The coulombic, voltaic and energy efficiencies of the flow battery under a cyclic regime, as well as the absorption spectra of the catholyte, were measured during its operation. The total amount of Br-containing compounds penetrating through the membrane into the anode space was also determined.
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Affiliation(s)
- Natalia V. Kartashova
- Faculty of Fundamental Physical and Chemical Engineering, Lomonosov Moscow State University, 119991 Moscow, Russia
- EMCPS Department, Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia
| | - Dmitry V. Konev
- Federal Research Center of Problem of Chemical Physics and Medicinal Chemistry RAS, 142432 Chernogolovka, Russia
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russia
| | - Pavel A. Loktionov
- EMCPS Department, Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia
- Federal Research Center of Problem of Chemical Physics and Medicinal Chemistry RAS, 142432 Chernogolovka, Russia
| | - Artem T. Glazkov
- EMCPS Department, Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russia
| | - Olga A. Goncharova
- Federal Research Center of Problem of Chemical Physics and Medicinal Chemistry RAS, 142432 Chernogolovka, Russia
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russia
| | - Mikhail M. Petrov
- EMCPS Department, Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia
| | - Anatoly E. Antipov
- EMCPS Department, Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia
| | - Mikhail A. Vorotyntsev
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russia
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Zader PA, Konev DV, Vorotyntsev MA. Theoretical Analysis of the pH Dependence of Evolution of the System Composition in the Course of Electrolysis of Acidic Aqueous Chloride Solutions. RUSS J ELECTROCHEM+ 2022. [DOI: 10.1134/s1023193522120084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Zader PA, Konev DV, Gun J, Lev O, Vorotyntsev MA. Theoretical Analysis of System’s Composition Changes in the Course of Electrolysis of Acidic Chloride Aqueous Solution. RUSS J ELECTROCHEM+ 2022. [DOI: 10.1134/s1023193522100123] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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