(554f) Advances in Redox-Electrodialysis for Desalination and Water Remediation

Water scarcity and contamination pose global challenges, impacting more than 67% of the world population who encounter severe water shortages for at least some of the year.¹ While electrochemical water treatment technologies have made significant advancements in addressing challenges related to the water-energy nexus, desalination processes often experience membrane fouling due to the presence of organic pollutants.

Here, we developed a cost-effective, energy-efficient, and fouling-free electrochemical water treatment technology by leveraging reversible redox reactions in the electrodialysis (redox-ED) platform.¹ By replacing the water-splitting reactions typically employed in the conventional ED system with reversible redox reactions, our system lowered the overall energy consumption for desalination by more than 50%. Additionally, to address membrane fouling in the presence of organic contaminants, we substituted costly and sensitive ion-exchange membranes (IEMs) with robust nanofiltration membranes (NFs), enabling the treatment of a wide range of charged substances from inorganic salts to organic contaminants.¹ By combining the water-soluble redox polymers with NFs, we removed a variety of chain lengths of carboxylates and per- and polyfluorinated substances (PFAS), while preventing membrane fouling and polymer crossover into the feed solution. The NF-enabled redox-ED system demonstrated the capability to treat a wide range of salinity levels, from brackish- to seawater, down to potable water salinity, with consistent energy consumption of 104 kJ/mol_NaCl. Furthermore, NF-enabled redox-ED showcased effective desalination and removal of carboxylates and PFAS contaminants within real wastewater matrices, highlighting its feasibility for a broad range of environmental and industrial wastewater treatment applications.

References
(1) Kim, N.; Elbert, J.; Kim, C.; Su, X. Redox-Copolymers for Nanofiltration-Enabled Electrodialysis. ACS Energy Letters 2023, 8 (5), 2097-2105.