Boron-Doped Diamond Anode-Driven Electrochemical Oxidization of Fluorinated Firefighting Wastewater-Contaminated Groundwater

Per- and polyfluoroalkyl substances (PFASs) in fluorinated firefighting wastewater (FFW), which are difficult to remediate using conventional technologies, represent a critical environmental hazard due to the extreme persistence and bioaccumulation potential of soil–groundwater systems. Niobium-supported boron-doped diamond (BDD) anodes were synthesized by microwave plasma chemical vapor deposition, and their performance in the electrochemical advanced oxidation processes (EAOPs) of FFW were systematically investigated. Under optimized conditions (100 mM Na2SO4 electrolyte with 100 mM peroxymonosulfate (PMS), current density of 33.3 mA/cm2, pH = 6), the BDD anode achieved near-complete mineralization, with 92.5% total organic carbon (TOC) removal and significant defluorination (77.5% F− release) within 240 min in simulated FFW-contaminated groundwater. For FFW-contaminated soil remediation, 90.2% TOC removal and 41.6% defluorination were achieved after 720 min under optimal treatment (water-to-soil ratio of 20:1). Quenching experiments and electron paramagnetic resonance (EPR) tests revealed that hydroxyl radicals (·OH) and singlet oxygen (1O2) were the predominant reactive species. Liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS) analysis indicated that PFASs were removed by shortened carbon chains, ultimately mineralizing to CO2 and F−. Toxicity assessment using Vibrio fischeri luminescence demonstrated a reduction in toxicity (from 99.8% to 20.9%), confirming the effective detoxification of BDD-based EAOPs. This work establishes BDD-based EAOPs as a promising technology for eliminating PFASs in groundwater and soil, offering theoretical insights into EAOPs and engineering solutions for PFAS remediation.