Dr. Cabezas-Cornejo, René

In this work, a study on the selective solvent extraction (SX) of molybdenum (Mo) and rhenium (Re) from a synthetic pregnant leach solution (PLS) has been carried out using nine different hydrophobic eutectic solvents (HES). Experiments were carried out using pure HES to evaluate the selective extraction and the subsequent stripping of these metal ions; then, the best HES was dissolved in kerosene to study the SX stoichiometry. Results indicated that only TOPO-based and N8881-Cl-based HES did not form emulsions, third phases or precipitates. These HES achieved a selective extraction because these obtained almost a 100% extraction towards Mo and Re from the PLS and very low extractions for Copper (Cu) and Iron (Fe) in one equilibrium stage. The stripping experiments showed that 95% of Mo and 22% of Re were stripped out from the loaded TOPO-based HDES, respectively, opening the possibility for the selective stripping of the metal species for further purification. Finally, the extraction stoichiometry was proposed based on an experimental slope analysis and the measurement of cations and anions transferred into the aqueous phase in which HES acts as a neutral extractant in the complexation of the Mo and Re salts. These promising results suggest that HES could be attractive for more sustainable mining industry.

Deep eutectic solvents (DES) are a category of a new class of solvents that can overcome some of the main drawbacks of typical solvents and ionic liquids (ILs). DES have been widely investigated and applied by the research community in several applications since their invention. Over the past years, the use of DES has been directed to the production of new materials and items for new products and processes. This is the case for the implementation of DES in various fields of chemical engineering directed to separations. DES have been very recently initiated to be combined into membranes for membrane processes. In this regard, this Review timely elucidates the current progress in utilizing this new generation of solvents in membrane preparation. In this work, different techniques, methods, and strategies for incorporating DES into polymer membranes for different concepts of membranes according to the final application have been reviewed. Particular emphasis has been devoted to the most relevant development works and results. After the current literature was analyzed, the main challenges and possibilities of DES in membranes were declared.

The separation of Levulinic (LA) acid and Formic acid (FA) from aqueous streams represents an important and challenging separation in biorefineries, where ionic liquids (ILs) provide a sustainable environment for liquid-liquid extractions of these acids. In this work, a COSMO-RS screening of bis (trifluoromethylsulfonil)imide [Tf2N]− based IL was first conducted and then followed by experimental validation to search for the most suitable cation for this separation. After the screening, ternary liquid-liquid equilibrium experiments at 298.15K and the subsequent data correlation using the Non-Random Two Liquid model (NRTL) were performed for future industrial implementation. Results indicated that the phosphonium cations, especially the trihexylthetradecyl phosphonium cation [P66614]+, produced the highest selectivity rates among all the experimentally measured ILs.

In this study, the theoretical design of ionic liquids (ILs) for predicting selective extraction of lithium from brines has been conducted using COSMO-RS. A theoretical model for the solvent extraction (SX) of the metal species present in brines was established considering extraction stoichiometry, the distribution of the extractants between aqueous and IL phases, and IL dissociation in the aqueous phase. Theoretical results were validated using experimental extraction percentages from previous works. Results indicate that, in general, the theoretical results for lithium extraction follow experimental trends, except from magnesium extraction. Finally, based on the model, an IL was proposed that was based on the phosphonium cation as the extractant, along with the phase modifier tributylphosphate (TBP) in an organic diluent in order to improve selectivity for lithium ex- traction over sodium. These results provide an insight for the application of ILs in lithium processing, avoiding the long purification times reported in the conventional process.

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.

Background: Rhenium(Re) is a highly valuable metal recovered from molybdenite leach liquors by solvent extraction (SX) using toxic organic solvents. This work proposes an extracting phase free of volatile organics composed by the ionic liquid (IL) trioctylmethylammonium benzoate [TOMA][BA] as the extractant, due to its ability to extract Re(VII), and the IL 1‐octyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide [omim][Tf2N] as the diluent, due to its high hydrophobicity where the extraction stoichiometry and process parameters such as the initial pH, the extractant concentration in the diluent and stripping using ammonium hydroxide () and sodium hydroxide () were assessed. Results: This extracting phase yielded high extraction percentages: 95% with only 3% (v/v) of [TOMA][BA] in [omim][Tf2N]. A detailed study of the SX stoichiometry was carried out through slope analysis, showing that the SX occurs in two steps: first, the extraction of acid; then, the extraction of the metal ion via anion exchange with the transfer of IL‐diluent anion to the aqueous phase. Additionally, the extracting phase was tested in a synthetic molybdenite leached pregnant leach solution, showing selectivity towards Re(VII) over Cu(II) and Fe(III) at very low extractant concentration. The stripping of Re(VII) from the loaded phase was also studied achieving 60% stripping in only one equilibrium step when using . Conclusion: This novel extracting phase, free of volatile organic, shows promising Re(VII) extraction for future industrial applications.