Hydrodynamic effects on the performance of an electrochemical reactor for destruction of copper cyanide-Part 1: in situ formation of the electrocatalytic film

An electrochemical reactor with stainless-steel electrodes was used for cyanide destruction and copper electrodeposition from dilute wastewater. With mechanical stirring, pumping or gas sparging, in situ deposition of a Cu oxyhydroxide film occurred on the anode at potentials >0.7V vs. AgCl/Ag and had electrocatalytic properties for oxidation of cyanides. The CuII/CuI ratio in the electrocatalytic film was found to vary with the hydrodynamic conditions. The minimum mechanical energy dissipation, ranging from 1.5 to 7.2Wm-3, necessary to create sufficient turbulence for film formation, was of a similar order of magnitude for all three means of transport enhancement. However, shear rates >410s-1 and shear stresses >0.41Nm-2 at the anode resulted in shearing of the film from the stainless-steel support.