PEDOT Particle Electrodes in a 3D Electrochemical Reactor for Degradation of Organic Contaminants in Water

Current electrochemical systems for contaminant degradation using conventional two-dimensional (2D) electrodes face mass-transfer and scalability limitations, especially for persistent organics. To address these limitations, we fabricated a three-dimensional (3D) reactor operated with a dilute, well-mixed suspension of poly(3,4-ethylenedioxythiophene) (PEDOT) particles and evaluated its performance, energy, and reusability, with hexazinone (HEX), a persistent triazine herbicide, as a model recalcitrant organic compound. PEDOT particles, synthesized via chemical polymerization, acted simultaneously as adsorbents, electrodes, and catalysts, achieving HEX removal efficiencies exceeding 98% at 5 V and 1 g/L particle loading (EE/O = 7 kWh/m3). Influencing factors, including applied voltage, electrolyte concentration, pH, PEDOT particle concentration, and initial HEX concentration, were systematically investigated. Radical quenching experiments identified hydroxyl radicals (•OH) as the primary reactive species responsible for HEX degradation. Adsorption–desorption experiments revealed simultaneous adsorption and degradation processes. Reusability tests indicated particle loss as the primary challenge, but embedding a Fe3O4 core in PEDOT particles enabled their magnetic recovery and stable performance over five cycles. A detailed degradation pathway involving multiple intermediates was proposed based on LC–MS/MS analysis. The research demonstrates the applicability of PEDOT suspensions in water treatment for the removal of recalcitrant organic micropollutants.