Evaluating the effectiveness of iron oxide (Fe3O4) nanoparticles vs. traditional chloride methods for copper cementation and recovery from industrial waste solutions by aluminium

Abstract

The cementation of copper on aluminium is a well-studied process, typically facilitated by chloride ions to overcome the insulating aluminium oxide layer. This study presents an alternative approach using magnetite (Fe₃O₄) nanoparticles as electron (redox) mediators, allowing the cementation process to occur despite the presence of the aluminium oxide layer. After optimizing the concentration of the Fe₃O₄ suspension, the pH, and the reaction time, the performance of this method was compared to the classical chloride ion-based approach. The nanoparticle assisted method achieved higher recovery (%) of copper, but at a slower pace. This difference in reaction speed explains the more compact, non-oxidize copper deposits observed by SEM and DRX, in contrast to the dendritic and airy deposits with a high fraction of Cu₂O obtained using the classical chloride method. Under optimized conditions, the method was applied for the recovery of Cu from two industrial PCB solutions, achieving excellent recoveries after adjusting the pH.