Anodic Dissolution Behavior in the Electrorefining of Al–Cu Alloys Using an EmImCl–AlCl3 Ionic Liquid

To produce high-purity Al from Al–Cu alloys, the dissolution behaviors of various Al–Cu binary alloy anodes in EmImCl–AlCl 3 ionic liquid have been investigated at 323 K. In the anodic polarization measurements, anodic current density peaks were observed at potentials of approximately 0.3 and 0.8 V vs Al/Al(III) for the Al–5.0%Cu casting alloy. In the constant potential electrolysis of the Al–5.0%Cu casting alloy and cold-rolled plate at 0.3 V, Al atoms in the matrix phase were preferentially dissolved followed by the formation of Al 2 Cu surface species. The dissolution of both Al 2 Cu and Al in the alloy matrix occurred during electrolysis at 0.8 and 1.2 V. Moreover, a Cu-rich layer derived from Al 2 Cu was formed on the cold-rolled plate surface at a potential of 0.8 V. Additionally, Cu was co-deposited on the cathode at the potentials at which Al 2 Cu dissolved. The dependence of the anodic dissolution behavior of the Al−Cu alloys on the potential in the EmImCl–AlCl 3 ionic liquid was analyzed. By controlling the anodic dissolution potential, the dissolution of Cu in Al 2 Cu into the electrolyte can be suppressed, thus considerably increasing the purity of electrorefined Al.