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Separation processes are essential across all areas of modern manufacturing, ranging from critical element recovery to chemical and biochemical purification. For example, maximizing metal production while reducing water and chemical usage is central to next-generation mining. At the same time, in chemical and biochemical manufacturing, discriminating between structurally-similar molecules can be the major bottleneck to industrial feasibility.

Electrochemical processes offer a promising route toward molecularly selective separations. By controlling redox electron transfer at interfaces, my lab develops separation processes that can reversibly bind and release target species. Our central aim is to fundamentally understand underlying molecular interactions while guiding innovations in electrochemical process design. First, we describe the development of redox-electrosorption processes for the recovery and purification of critical metals, including platinum group metals (PGMs) and rare-earth elements (REEs). We elucidate the key intermolecular interactions at redox-copolymers that drive selectivity, including the role of charge-transfer and solvation. Next, we translate these single-site binding concepts beyond electrosorption to establish an electrochemical liquid–liquid extraction process. By carefully tailoring redox-active hydrophobic ligands, we unlock scalability in a redox-flow electrochemical architecture that combines continuous operation with redox-mediated reversibility. In particular, we highlight the importance of multi-stage process design in electrochemical separations for enabling industrially-relevant flowsheets.  

Overall, redox-electrochemical platforms have shown generalizability across distinct separation modes and diverse application fields. We envision the continued growth and translation of electrochemical separations for industrially-relevant contexts.

Xiao Su is an Associate Professor in Chemical and Biomolecular Engineering at the University of Illinois, Urbana-Champaign. He obtained his Bachelor in Applied Sciences in Chemical Engineering from the University of Waterloo in 2011. He completed his PhD in Chemical Engineering from MIT in 2017, working under the supervision of Professor T. Alan Hatton from Chemical Engineering and Professor Timothy F. Jamison from Chemistry.

Since joining Illinois in 2019, his research seeks to develop new electrochemically-mediated separations through a combination of molecular design and electrochemical engineering. His team has tackled global challenges such as critical element recovery and materials recycling, sustainable mining, environmental remediation and water treatment, as well as chemical and biochemical manufacturing. A unique focus has been on understanding and leveraging redox-electron transfer at interfaces to achieve selective ion separations, and electrochemically combining reaction and separations for process intensification.

Xiao has been the recipient of the NSF CAREER Award (2019), the ACS Victor K. Lamer Award in Colloids & Surface Chemistry (2020), the ISE-Elsevier Prize for Green Electrochemistry (2021), the Merck Innovation Award (2021), the ACS Unilever Award in Colloids & Surface Chemistry (2023), the AIChE FRI/Kunesh Awards in Separations (2023), the ACS Satinder Ahuja Young Investigator Award in Separation Science (2024), and the DOE Early Career Award (2024). Xiao’s teaching has also been recognized by the List of Excellent Teachers (2019, 2022), and the School of Chemical Sciences Teaching Award (SCS) in 2023. He is the co-founder of Valor Metals Inc, a spinoff from his research lab focusing on commercialization of separation processes for critical element recovery.

Su Research Group Website