The growing global population is driving increased demand for resources, particularly rare earth and critical metals, which are essential for advanced technologies. Under net-zero emission goals, demand for these materials is projected to be 16 times higher by 2050 compared to 2020. Meanwhile, electronic waste—one of the fastest-growing waste streams—continues to rise, yet only 17% was properly recycled as of 2020. Recycling electronic waste is challenging due to the complex mixture of metals with diverse physicochemical properties. Hydrometallurgy, while more efficient and cost-effective than other methods, still requires several steps—starting with chemical leaching and followed by various separation techniques. Our work focuses on understanding metal-chelate complexes and metal-solvent interactions at the molecular level, aiming to leverage these insights to enable a more efficient and sustainable metal recovery. We use molecular quasi-chemical theory (m-QCT), a statistical mechanical method that evaluates the interactions between metals, chelating agents, solvents, and their resulting complexes by calculating their excess free energies via a combination of ab initio and classical calculations while explicitly accounting for electronic polarizability and other key electronic effects that influence chelation. We have successfully applied this approach to describe the thermodynamic stability of chelated metals—such as gallium, cobalt, and nickel—providing insight into which chelating agents and solvents are most effective for selectively recovering specific metals. Future studies could potentially explore their kinetic stability to gain a more complete understanding of the overall system.
