Selective adsorption of organic anions in a flow cell with asymmetric redox active electrodes

• Published in: Water research (Oxford) 2020-09, Vol.182, p.115963-115963, Article 115963
• Main Authors: He, Fan, Hemmatifar, Ali, Bazant, Martin Z., Hatton, T. Alan
• Format: Article
• Language: English
• Subjects: Electrochemical adsorption; Environmental remediation; Micropollutants; Redox active electrodes; Selective adsorption
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2020.115963

Electrochemically mediated adsorption is an emerging technology that utilizes redox active (or Faradaic) materials and has exhibited high salt adsorption capacity and superb ion selectivity. Here, we use a redox polymer polyvinylferrocene (PVFc) as the anode and a conducting polymer polypyrrole doped with a large anionic surfactant (pPy-DBS) as the cathode for selective electrochemical removal of inorganic and organic components. We fabricated a flow system with alternating adsorption/desorption steps incorporating an electrosorption cell and inline probes (ultraviolet–visible spectroscopy, conductivity and pH sensors) to demonstrate on-the-fly quantification of the ion adsorption performance. The flow system provides a more realistic evaluation of dynamic selectivity for the active materials during cyclic operation than that based on a single equilibrium adsorption step in batch. Our results show a three-fold (cycle) selectivity toward the removal of benzoate, as a representative organic anion, against a 50-fold abundance of perchlorate supporting anion, indicating that electrochemically mediated adsorption is a promising technology for waste water remediation applications. [Display omitted] •Redox-active electrodes for electrochemically-mediated selective adsorption.•Design and fabrication of a flow platform with multiple inline detectors.•Ultra-high salt adsorption rate of 5.6 mg g−1 min−1.•Selective removal of benzoate as a model compound of toxic carboxylate pollutants.•Selectivity of 3 in presence of highly abundant supporting anions (50-fold).