Critical metals such as gold, palladium, tellurium, lithium, and the rare earths are now pervasive in technology and used regularly in our daily lives. In many cases, mining and purification practices for critical metals and harmful to people and the environment. It is therefore attractive to try and reclaim such metals from post-consumer waste materials, especially electronic materials. However, in many cases, chemistry and engineering to recycle specific critical metals is lacking, compared to the cost of obtaining pure metals from primary sources. In this talk, efforts to develop fundamental new separations chemistry for recycling critical metals will be presented. Among these, efficient, inter-f-element separations, such as within the rare earths, remain a perennial challenge. My group has been interested in triggering element-specific changes, for example through highly specific structural differences, to achieve efficient separations through new thermodynamic modes. And in an orthogonal approach, to express differences in metal complexes through variable rates of some chemical change – a separations chemistry through kinetics. Both methods allow direct connection of coordination chemistry to macroscopic properties for separations. These connections have enabled new modes in solid-liquid extraction to complement solvent extraction for specialized applications. For this talk, our latest results on chelating and redox active ligand frameworks and their applications in thermodynamic and kinetic separations of elements will be presented. Our results highlight this exciting direction for inorganic chemistry, targeting new chemistry toward reclaiming rare, precious, and critical metals from waste.

Coordination chemistry principles applied to sustainable separations of metal ions

ACS Spring Meeting 2021

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