Redox-Copolymers for Nanofiltration-Enabled Electrodialysis

Robust, energy-efficient separation technologies for desalination and the removal of organic contaminants are critical in addressing growing concerns about water shortage and water pollution. Here, we propose a generalized strategy for advancing electrodialysis technologies using redox-flow concepts, by implementing a water-soluble redox-copolymer, poly(ferrocenylpropylmethacrylamide-co-[2-(methacryloyloxy)ethyl]trimethylammonium chloride), P(FPMAm-co-METAC), to eliminate the need for anion-exchange membranes (AEMs) and deploy cheaper and more robust nanofiltration membranes (NFs). The effective membrane retention of the redox material and stable redox activity facilitate the continuous desalination of various source waters, including brackish water, seawater, and wastewater, to produce potable water and remove organic contaminants without membrane fouling or polymer crossover. Leveraging the reversible redox reaction of ferrocene reduces energy consumption by 88% within a single-unit cell compared to conventional ED. In addition, utilizing reusable redox-copolymer and cost-effective NFs promotes economic feasibility, achieving a water production cost of $0.13 m–3. Overall, the combination of redox-copolymer in flow and NFs provides a new avenue to address water contamination caused by organic pollutants and water scarcity in an energy efficient manner.