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Electrochemical characteristics of manganese in cyanide solutions

1963; Elsevier BV; Volume: 5; Issue: 2 Linguagem: Inglês

10.1016/0022-0728(63)80127-8

2590-2946

Stephen A. Moros, Louis Meites,

Electrocatalysts for Energy Conversion

A plot of continuous faradaic current vs working-electrode potential for the controlled-potential electrolysis of a neutral 1 F sodium cyanide solution at a large stirred mercury pool electrode consists of two portions, which correspond to the reductions of hydrogen cyanide, and water. The final electrolysis current is increased by the presence of manganese (I), and it is shown that this increase can be accounted for quantitatively by a mechanism involving the hydrolysis of the binuclear species (CN)5Mn—O—Mn(CN)10−5 to give Mn(OH)(CN)5−5 (K = ca. 5.10 −7 and the reaction of the latter ion with hydrogen cyanide (k = ca. i 1 l/mole−1 sec−1) to give manganese (II) and hydrogen. Coulometric data show that the reduction of manganese (II) in a cyanide solution increases the rate of the simultaneous reduction of water, and this is interpreted on the basis of the probability of dissociation of the bridge structure electrode — HOH —(CN)Mn(CN)4−5 after an electron has been transferred from the electrode but before it has been transferred through the bridge to the manganese complex.