Removal of iron and nickel from solutions by application of electrical fields

Metallic impurities such as Ni Fe, Cu ions in chromium plating solutions ca n be removed by electromigration followed by electrodeposition or coagulati ion using a porous pot, suspended in the bath and containing a lead cathode . In the same process, Cr(III) is oxidized to Cr (VI) at the insoluble lead anode leading to regeneration of the plating solution. Previous research a nd data from industrial operations have indicated the "porous pot" method c ould be a cost-effective and environmentally friendly method to continuousl y separate impurities and recycle spent chromium solutions. However, no dat a are available that relate the various concentrations of impurities to the extent and the rate of their removal. This investigation focused on the us e of five suitable catholytes for the removal of impurities. Up to 60% nick el and 52% iron removal were observed in orthophosphoric acid and sodium mo nophosphate catholytes respectively. In addition to these two electrolytes, chromic acid appears to be a most suitable catholyte for purification when more than one metallic impurity is present in the spent solution.