We explore the use of asymmetric supercapacitor electrode assemblies of novel architecture for the selective electrosorption of a range of molecular species of environmental concern. The process relies on the strong interactions between targetted analytes and appropriate redox-active polymers when they are in one oxidation state and not the other.  The release of the captured compounds can be realized on reversing the oxidation state of the polymers. A range of different process streams are amenable to treatment in this manner, and we will report on (i)  selective separation of organic anions from a significant excess of supporting electrolyte, (ii) heavy metal ions from solution,  and (iii) CO<sub>2</sub> from dilute gas feeds. The basic concepts, including the design, preparation and electrochemical characterization of the electrode assemblies and the dynamic uptake and release of the targeted compounds under a range of different operating conditions, will be discussed.<br/> <br/>An important consideration in the electrochmically-mediated treatment of process streams is that side-reactions at electrode interfaces can be economically and energetically costly, since they can affect the electrode stability as well as impact electrochemical performance. In aqueous chemistry, for instance, water electrolysis at the cathode is a major challenge as it drains current density that could otherwise be applied in a useful process, can dramatically affect the solution chemistry through increases in pH, and can impact the stability of the anode itself.  We conclude the presentation with a discussion on how appropriate matching of asymmetric redox electrodes can fully suppress the hydroxide generation reaction and enhance current efficiency.

Redox-mediated electrosorption for chemical and environmental separations

251st National Meeting (2016)

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