As some portion of manganese ion is oxidized at the anode during the electrolysis of zinc, these phenomena have been observed by the spectrophotometry and chemical analysis. The results are as follows. MnO
4- is first formed by the anodic oxidation of Mn
+2 in the zinc electrolyte solution. This MnO
4- immediately reacts with Mn
+2 and is converted into fairly stable, Mn
+3, and finaly MnO
2 is formed. The formation of MnO
2 is much greater in case of pure lead or lead-silver anode than in platinum anode.
The effects of Mn
+2, Mn
+3, MnO
4- and floated Mn0
2 on the current efficiencies and potentials on electrodeposited zinc have been observed. It was found that these effects are not so great, but the presence of MnO
4- or Mn
+3 decreases the current efficiencies to some extent, and indicates the negative potential, as compared with Mn
+2.
The effects of MnO
2 formed on the surface of the anode during the zinc electrolysis have been determined, using the pure lead and lead-silver alloy anodes coated with a layer of MnO
2, prepared by the electrolytic oxidation in MnSO
4 solution at their optimum conditions. The MnO
2 film formed on the anode surfacebecome more coherent, when the electrolytic oxidation is done at higher temperature, and in case of leadsilver alloy anode than in case of pure lead anode. The MnO
2 film on the anode seems to have little effect decrease the lead content in electrodeposited zinc.
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