ElectroLeaching-ElectroChemical Deposition (EL-ECD) of gold and palladium in a deep eutectic solvent (DES)

• Published in: Journal of environmental chemical engineering 2022-06, Vol.10 (3), p.108004, Article 108004
• Main Authors: Villemejeanne, Benoit, Legeai, Sophie, Meux, Eric, Dourdain, Sandrine, Mendil-Jakani, Hakima, Billy, Emmanuel
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Deep eutectic solvents; Electrochemistry; Environmental Sciences; Material chemistry; Precious metals recovery
• ISSN: 2213-3437; 2213-3437; 2213-2929
• DOI: 10.1016/j.jece.2022.108004

Precious metals (PM) refining from E-waste recycling are based on hazardous hydrometallurgical processes, including cyanide leaching for gold or aqua regia leaching for palladium, which generates an important wastewater production. In this paper, we present an electrochemical process, based on low viscous deep eutectic solvents ChCl:EG 1:2 and ChCl:EG 1:3. Au and Pd electrochemical leaching and deposition parameters, but also gold and palladium speciation were studied. A one-step ElectroLeaching-Electrochemical Deposition Process (EL-ECD) in a single cell is proposed with high faradic yield of metal recovery. This process avoids electrolyte degradation and is advantageous to limit solvent losses and workers exposition. Electroleaching (EL) and simultaneous ElectroChemical Deposition (ECD) cell for Au and Pd recovery – Gold deposited on glassy carbon cathode. [Display omitted] •Gold and palladium recovery was achieved by ElectroLeaching-ElectroChemical Deposition (EL-ECD) in a deep eutectic solvent.•Au and Pd ElectroLeaching (EL) leads to AuCl2- and PdCl42- formation with a faradic yield ranged between 98 % and 100 %.•Au and Pd ElectroChemical Deposition (ECD) is controlled by metal complexes diffusion from the bulk toward the electrode.•Au and Pd Electroleaching and simultaneous ElectroChemical Deposition was achieved in ChCl:EG mixture with a faradic yield ranged between 85 % and 100 %.