Electrochemically Mediated Sustainable Separations in Water

Separation processes are employed intensively for purification purposes in chemical production, as well as potable water generation and environmental remediation. Electrochemical separation techniques have long been studied and have been subsequently implemented for commercial application in various industries, with their modularity and capability for precise control of operating conditions serving as defining positive attributes. As global resource demand continues to rise, there is an urgency to further enhance separation process efficiency. Electrochemically mediated sustainable separations are designed to address this challenge by providing greater energy efficiency and engineered targeting of specific analytes while maintaining the inherent compact and portable nature of electrochemical systems. Recent advances in the field have leveraged redox-active species as heterogeneously functionalized composites on electrode surfaces to perform separations at the solid–solution interface via methods such as electrochemical conversion, electrochemically mediated binding, and electrochemically modulated hydrophilicity tuning. Electroactive materials help to improve removal capacity through their heightened pseudocapacitance and can also impart molecular recognition through redox-enhanced complex formation, intercalation, ion-imprinting, hydrophilic interactions, and conversion processes for the selective removal of various charged and neutral compounds. The complementary combination of two redox-active species into an asymmetric framework provides even greater functionality to electrochemical separation cells by increasing adsorption amounts, suppressing changes in water chemistry, reducing energetic requirements, inhibiting unwanted side-reactions of target analytes, and enabling the conversion of toxic substances via reactive separation. There is a broad scope for the continued development of electrochemical concepts into next-generation technologies for sustainable water-based electrochemical separations and other related areas.