Strong hydrophobic affinity and enhanced •OH generation boost energy-efficient electrochemical destruction of perfluorooctanoic acid on robust ceramic/PbO₂-PTFE anode

The progress on perfluorooctanoic acid (PFOA) removal from wastewater is of great importance. Electrochemical advanced oxidation processes (EAOPs) are effective, but always trigger concerns involving energy consumption and stability of electrode materials. In this work, a tubular polytetrafluoroethylene (PTFE) doped PbO₂ film anode supported over ceramic (ceramic/PbO₂-PTFE) was fabricated and used for energy-efficient destruction of ppm-level PFOA. Given initial PFOA concentrations of 20 mg L⁻¹, this anode outcompetes conventional Ti/SnO₂-Sb/PbO₂ anode with 15-fold in apparent rate constant (k_obs), 0.36-fold in electric energy per order of magnitude of PFOA removed (E_EO), and 640-fold in released F⁻ by energy consumption per unit ([F⁻] / E). Experimental results under different potentials and density functional theory (DFT) calculations confirm that PFOA degradation is initiated by direct electron transfer (DET) and enabled by •OH attack. Ceramic/PbO₂-PTFE features stronger hydrophobic affinity with PFOA, and more •OH generation than Ti/SnO₂-Sb/PbO₂, which boosts its good performance for PFOA degradation/defluorination. This anode exhibits 2.7-fold in service life than conventional Ti/SnO₂-Sb/PbO₂, and high tolerance for free fluorides, which expands its application for concentrated PFOA in waste stream. © 2021 Elsevier B.V.