Collaborative Research: CAS-SC: Investigating the Mild Ligand-based Oxidative Dissolution of E-waste Metals and Their Reductive Recovery

In this project, funded by Chemical Structure, Dynamics & Mechanisms-B Program of the Chemistry Division, Professors Kristopher Waynant and James Moberly of the Departments of Chemistry and Chemical and Biological Engineering, respectively at the University of Idaho along with Professor Elliott Hulley of the Department of Chemistry at the University of Wyoming are developing a novel mild method for the sustainable recycling of e-waste metals from pure and mixed metal systems. The goal of this project is to create a series of unique chemicals that dissolve e-waste metals and study the digestion and recovery processes. This project could develop a unique understanding of the essential components critical to develop an innovative technology for sustainable recovery of metals. Outreach activities include a series of course-based undergraduate research experiences to allow students to take part in the project goals. It will also incorporate sustainable chemical principles into undergraduate teaching laboratory. Redox-active ligands, chelators that induce redox events, will be designed for the oxidative dissolution of zerovalent metals from e-waste. A series of ligands based on the azothioformamide 1,3-heterodiene framework will be studied. Both computational and experimental approaches will be coupled to investigate ligand induced dissolution and recovery of e-waste metals. Additionally, valorization, host-guest mechanism deduction, and the development of new reactions and green chemistry will be explored to build a critical materials and precious metals recycling program. Preliminary data has identified 1) a series of ligand dissection points that may govern the efficacy of oxidative dissolution; 2) that substitution patterns on ligands affect coordination of metal salts, giving clues to which ligand modifications may be most selective for dissolution / coordination; 3) recovery of metals is viable by electrochemical means and may be possible by chemical reduction to regain ligands and purify metals toward a circular, sustainable process. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.