The peculiarities of electrooxidation of Mn<sup>2+</sup> to MnO<sub>2</sub> in acetate electrolyte




Mn2 acetate complexes, electrooxidation, quantum-chemical modeling


The results of investigation of Mn2+ electrooxidation mechanism in the presence of acetate ions have been presented. The kinetic measurements were supplemented by quantum-chemical modeling. The calculated value of the redox potential of [Mn(H2O)5Ac]+/[Mn(H2O)5Ac]2+ system was compared with experimental data obtained at pH 5.2. The similar values have given a reason to assume the direct electrooxidation of ion Mn2+ to Mn3+ like complex [Mn(H2O)5Ac]+. The process occurs according to inner-sphere mechanism due to direct contact of the complex with the electrode through the carboxyl group. The quantum-chemical calculations have shown the impossibility of elimination of second electron without considerable reorganization of the complex [Mn(H2O)5Ac]2+. The final product of electrooxidation of Mn2+ acetate complex, manganese dioxide, was formed as a result of [Mn(H2O)5Ac]2+ disproportionation with subsequent hydrolysis of the [Mn(H2O)5Ac]3+ complex. In weakly acidic solution (pH above 4) due to reducing the number of [Mn(H2O)5Ac]+ complexes, electrooxidation of manganese ions were occurred by a similar mechanism to the acid sulphate solution, i. e. by radicals, produced by electrooxidation of water molecules.

Author Biographies

Viktor F. Vargalyuk, Oles Honchar Dnipropetrovsk National University, 72 Gagarin Ave., Dnipropetrovsk 49010

Декан химического факультета, д.х.н, профессор

Veronika V. Poltavets, Oles Honchar Dnipropetrovsk National University, 72 Gagarin Ave., Dnipropetrovsk 49010

Senior lecturer

Ludmila V. Shevchenko, Oles Honchar Dnipropetrovsk National University, 72 Gagarin Ave., Dnipropetrovsk 49010

Assistant professor, PhD


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