ROTATING-RING-DISK ELECTRODE STUDIES OF CYANOCUPROUS ION OXIDATION ON PLATINUM

The anodic oxidation of cyanide ion is catalyzed by the addition of cuprous ion. Studies with a platinum-platinum rotating ring-disk electrode indicate that at the anode cyanocuprous ion is oxidized to adsorbed cyanocupric ion which then decomposes primarily by a heterogeneous quasi-second-order intracomplex redox reaction. The rate of this heterogeneous reaction increases roughly linearly with homogeneous cyanide concentration, indicating a fundamentally different reaction mechanism from the homogeneous decomposition of the tetracyanocupric ion. An analytic model has been developed to simulate the effect of the heterogeneous reaction on the rotating ring-disk electrode system. This model reproduces adequately the collection efficiencies observed experimentally.