Résumé
Nowadays, Waste Electrical and Electronic Equipment (WEEE) are rising all over the world. Furthermore, e-waste (mobiles, tablets…) could contain some important concentration of critical, rare, or precious metals. So on, metal valorization from end-of-life electronic appliances is one of the most important challenge regarding raw materials depletion and supply but also waste generation. Currently, precious metals recovery from end-of-life products imply pyrometallurgical and hydrometallurgical processes. However, hydrometallurgical processes used to refine precious metals presents some hazardous drawbacks (harmful reagents for the human life and the earth like cyanide or strong acids, wastewater generation). The use of Ionic Liquids (IL) or Deep Eutectic Solvents (DES) could represent a solution more respectful of Green chemistry principles to this application. Indeed, these solvents have a low vapor pressure and are non-flammable which considerably reduce hazards. Furthermore, they have a great stability (thermal and electrochemical) and should act like efficient complexing agents, two very useful properties for precious metals leaching without any solvent degradation. Therefore, IL and DES are already used at the pilot stage to recover metals [1][2][3].Recently, CEA Liten and Jean Lamour Institute obtained promising results on a single step electroleaching-electrodeposition (El-Ed) process using ionic liquids for Pt recovery from a membrane electrode assembly (MEA)[4].However similar process for precious metals contained in WEEE is not straightforward. In present work, we evaluate ionic solvent relevance for developing an El-Ed process for gold and palladium recovery. We present here electrochemical behavior and leaching and deposition potential data in IL-mixture and DES for gold and palladium, which are required for this process. Promising ionic liquids tested exhibit gold electroleaching rate comparable to in the same magnitude of conventional cyanide solution meanwhile DES exhibit faster leaching kinetics. For these promising electrolytes, we present other relevant properties including electrochemical stability, density, viscosity, and conductivity to further optimize leaching step and recovery steps.1.A.P. Abbott, G. Frisch, K. S. Ryder, Annual Reports Section « A » (Inorganic Chemistry), 104 (2008) 21. 2.ANR program, « Strategic metal recycling in Ionic Liquids by EXtraction and Electrodeposition process», 20143.https://www.seren-ag.com/rem-magnet-recycling/4.M. Balva, S. Legeai, N. Leclerc, ChemSusChem, 10 (2017) 2922 2935.