Recycle of Contaminated Zinc-Nickel Plating Bath by Selective Recovery of Iron

Electroplating is a preferred method of coating the surface of metallic materials such as steel for wear and appearance reasons. Recently, zinc, nickel, or zinc-nickel coatings have been widely used to prevent corrosion of vehicle parts such as brake pads and connecting equipment. However, in the plating bath used in the plating processes, iron contamination might occur due to the partial dissolution of the metal parts over time, causing dark-colored defects on the plating material during electroplating. In this study, the recycling of the plating bath electrolyte by precipitation of iron ions from the solution was investigated. The addition of 7 g/L zinc dust at 30° C minimized the iron concentration in a short time (20 minutes) without affecting the quality and content of the coating bath. The chemical and physical analyses of the precipitate and electrolytes were performed by AAS, XRD, and EDX. The galvanic quality of the decontaminated electrolyte was tested at a current density of 250 A /m2 and 298 K.