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

Abstract

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 > 0.7 V vs. AgCl/Ag and had electrocatalytic properties for oxidation of cyanides. The Cu II / Cu I ratio in the electrocatalytic film was found to vary with the hydrodynamic conditions. The minimum mechanical energy dissipation, ranging from 1.5 to 7.2 W m - 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 > 410 s - 1 and shear stresses > 0.41 N m - 2 at the anode resulted in shearing of the film from the stainless-steel support.