Dr. Cabezas-Cornejo, René

In this work, the factors that determine a high or low extraction performance when using ionic liquids (ILs) as diluents in the solvent extraction of Rhenium (Re(VII)) from aqueous solutions were studied by means of experiments, quantum chemical (QC) calculations, and COSMO-RS. For this purpose, kerosene and the ionic liquids (ILs) 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C4C1im][Tf2N], or 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide [C8C1im][Tf2N] were used as diluents to determine de effect of alkyl chain of ILs, and two high molecular weight amines: trioctylamine (TOA) and Alamine 336 (Al336) were used as the extractants. The results indicated that the so-called reference extracting phase TOA in kerosene achieved 99% extraction percentages. On the contrary, a lower performance was observed when replacing kerosene with any of both ILs. This reduction was mainly due to two reasons. First, the IL dissociates where the cation takes part in the formed complex, hindering the TOA-perrhenate bonding, and second, the formed complex that contains IL cations shows poor dissolution in the diluent phase. This could be avoided by means of long alkyl chain imidazolium bis(trifluoromethylsulfonyl)imide-based ILs. Additionally, operating parameters such as equilibrium stages and concentration of the stripping agent were studied. Promising results were obtained by replacing TOA with Al336 dissolved in the IL [C8C1im][Tf2N], showing very similar results with the reference extracting phase.

Cobalt (Co) stands out as one of the most critical metals in contemporary use, particularly due to its increasing demand in technological products and especially in electromobility. Over the years, ionic liquids (ILs) have provided a green alternative to volatile organic solvents in hydrometallurgy due to their outstanding properties, such as the negligible vapor pressure and their increased selectivity provided in separation processes, which opens the possibility to ramp up the Co-production while maintaining sustainable mining processes. Thus, this review offers a complete comprehensive and critical summary of published works on the use of ILs in the hydrometallurgy of Co, starting from the leaching from a primary source by conventional methods and then, from the pregnant leach solution (PLS) focuses on the advantages and disadvantages of solvent extraction (SX) in different aqueous media (chlorinated, nitrated, and sulfated) in which ILs are used to separate selectively Co from a multi-metal mixture. In the following section, its recovery from the loaded organic phase by acid stripping is discussed. Finally, this review provides the challenges that ILs should overcome to be viable for large-scale industrial applications and the opportunities that exhibit for selective recovery of Co from PLS capitalizing.