Degradation of bisphenol A using a three-dimensional electrochemical reactor: Synergistic effects of H2O2 and mechanistic insights

Despite the growing use of three-dimensional electrochemical reactor (3DER) in wastewater treatment, the synergistic mechanisms and degradation performance of 3DER coupled with hydrogen peroxide (H 2 O 2 ) using iron concentrate (IC) as particle electrodes (PEs) remained largely unexplored. In this study, a 3DER utilizing IC as PEs and H 2 O 2 as the oxidant (3DER-H 2 O 2 system) was developed for bisphenol A (BPA) degradation. Physicochemical characteristics reveal that IC possessed high iron content (54.8 wt%), favorable electrical conductivity (1.9 ×10 4 S·m −1 ), and structural stability, making it an ideal PEs material. Under optimal operating conditions (5 mM of H 2 O 2 concentration, 0.4 A of current intensity, 2 g·L −1 of PEs dosage, 10 mm of interelectrode spacing, and initial pH value of 7), the 3DER-H 2 O 2 system achieved 89.7% of BPA removal (initial concentration 10 mg·L −1 ) within 70 min, with energy consumption (EC) of 38.15 Wh·L −1 and specific energy consumption (SEC) of 4.27 Wh·mg −1 . Comparative experiments demonstrated significant synergistic effects (synergy factor >10) of the system, attributed to enhanced reactive oxygen species (ROS) generation and improved mass transfer efficiency. Electron paramagnetic resonance and quenching experiments identified hydroxyl radicals (HO • ) as the dominant ROS, while sulfate radicals (SO 4 • ⁻) contributed minor roles in the system. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis BPA was mineralized into CO 2 and H 2 O via aromatic substitution and C–C cleavage, with acute toxicity decreasing progressively. Stability tests showed that 49.7% of BPA removal efficiency after four cycles, with heavy metal leaching remaining within safety limits. This study provides a cost-effective technical solution for BPA-contaminated wastewater treatment and promoted the engineering application of 3DER technology for emerging contaminant remediation.