Abstract:

Electric fields and electrochemical reactions can unlock new separation pathways. While electrochemical separations have been explored previously for water desalination, their translation to value-added chemical manufacturing or resource recovery has been hampered by the lack of molecular selectivity. Here, we present the molecular design of redox-responsive materials for enabling selective electrochemical separations.

Redox electron-transfer can be leveraged to tune interfacial selectivity, reversibility, and even synergistic coupling of reaction and separations. We combine synthetic design, in-situ interfacial measurements, and computational simulations to investigate the binding mechanisms of target ions at electrodes, and elucidate the contributing effects of charge-transfer, electrostatics, and solvation. These mechanistic insights can guide the discrimination of structurally similar ions, for applications ranging from critical element recovery to even enantioselective separations. Separately, we demonstrate how copolymer design and electrochemical systems engineering can innovate redox-electrodialysis. These integrated processes can have an impact on multicomponent separations, including the simultaneous abatement of ultra-short-, short-, and long-chain PFAS from semiconductor manufacturing.

Finally, we highlight the generalizability of the redox-mediated separations beyond adsorption, and extend the concepts to electrochemical liquid-liquid extraction platforms. We discuss how these continuous technologies can be scalable, and provide a path for industrial translation in e-waste recycling and mineral processing.