Nanostructured Conducting Polymers for Electrochemically-mediated Separations of Organic Pollutants from Water

Presenter: 

Yinying Ren

Authors: 

Yinying Ren, Xianwen Mao, Emily Penn, and T. Alan Hatton

Author Affiliation: 

Department of Chemical Engineering, MIT

Abstract: 

Many stimuli-responsive polymeric adsorbents with chemical (e.g., CO2, pH, oxidizing/reducing agents) or thermal responsiveness have been developed for separations of organic compounds from water. Electrochemical stimuli, however, have rarely been used to modulate the affinity between target neutral molecules and polymeric adsorbents. Here, we report a novel approach for the separation of organic pollutants from water using an intrinsically conducting polymer, polypyrrole (PPy), doped with surfactant AOT as an adsorbent. We have discovered a new approach to fabricate PPy that results in nanoporous strucutres and can undergo hydrophobic-hydrophilic transitions under electrochemical control. In its hydrophobic state, the PPy polymer can adsorb organic uncharged species from water, and can subsequently be regenerated by application of an electrical potential to switch the polymer to its hydrophilic state and induce the release of adsorbed pollutants, or their electrochemical decomposition. The PPy polymer has been taken through multiple adsorption-regeneration cycles without decay in its adsorption capacity, showing the robustness and reusability of the adsorbent. Our novel fabrication method also creates hierarchical porous structures in the PPy polymer which allows for increased adsorption capacity of greater than 100 mg pollutant/g polymer for a model organic pollutant molecule.