CBE Seminar: T. Alan Hatton
Redox-Mediated Electro-sorption for Chemical and Environmental Separations
We explore the use of asymmetric supercapacitor electrode assemblies of novel architecture for the selective electro-sorption of a range of molecular species of environmental concern. The process relies on the strong interactions between targeted 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 number 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) CO2 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.
An important consideration in the electrochemically-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
T. Alan Hatton is the Ralph Landau Professor and Director of the David H. Koch School of Chemical Engineering Practice at the Massachusetts Institute of Technology, Co-Director of the MIT Energy Initiative Center for Carbon Capture, Utilization and Storage, an Honorary Professorial Fellow of the University of Melbourne in Australia, and an Adjunct Professor at Curtin University. He obtained his BSc and MSc degrees in Chemical Engineering at the University of Natal, Durban, South Africa, and worked at the Council for Scientific and Industrial Research in Pretoria for three years before attending the University of Wisconsin, Madison, to obtain his PhD. His research interests encompass self-assembly of surfactants and block copolymers, synthesis and functionalization of magnetic nanoparticles and metal-organic frameworks for chemical, biological and environmental separations and catalysis, and the exploitation of stimuli-responsive materials for chemical and pharmaceutical processing applications. The most recent focus of his research has been on electrochemically-mediated CO2 capture and conversion, and on electro-swing sorption processes for trace contaminants of emerging concern in water supplies.