Dr. Cabezas-Cornejo, René

Ionic liquids have attracted widespread attention due to their low melting points, low vapor pressure, and non-flammability. However, their application at industrial scale is uncommon due to high costs and low recovering efficiency of the ionic liquids within the process. To reduce the costs and environmental effects of ionic liquids, this study proposes to use industrial microwave irradiation to recover eight different ionic liquids from water. The heating kinetics and identification between dielectric and convective heat properties were studied. Imidazolium-based ionic liquids showed the best results, reaching higher temperatures in shorter periods of time. Ionic liquid (bis(trifluoromethylsulfonyl) trihexyl(tetradecyl) phosphonium imide ([P6,6,6,14][Tf2N]) reached a temperature of 398 K in 360 s). On the other hand, the ionic liquid (1-butyl-3-methylimidazolium methylsulfate ([bmim][CH3OSO3]) reached a temperature of 417 K in 150 s). the ionic liquid Microwave heating experiments (water/ionic liquids) demonstrated a 90% recovery in ∼200 s for 1-octyl-3-methylimidazolium chloride ([omim][Cl]). Finally, the time used to heat-up ionic liquids with microwave irradiation was 15 times shorter than the time employed with vacuum-assisted distillation. Therefore, microwave-assisted heating has shown to be an excellent form to heat ionic liquids to decrease the cost of the extraction process and improve their reusability.

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.