Fe3O4 loaded on ball milling biochar enhanced bisphenol a removal by activating persulfate: Performance and activating mechanism

In this study, pristine biochar (BC), ball milling biochar (MBC), Fe 3 O 4 modified BC (Fe 3 O 4 @BC), and Fe 3 O 4 modified MBC (Fe 3 O 4 @MBC) were prepared to compare the Bisphenol A (BPA) removal efficiency by activating persulfate (PDS). All catalysts exhibited excellent degradation rather than adsorption in the PDS system, and Fe 3 O 4 @MBC800 had the best BPA removal efficiency, with 96.73% degradation and negligible 1.43% adsorption due to the synergistic effect between MBC800 and Fe 3 O 4 particles. Radical quenching experiments and electron paramagnetic resonance analysis indicated radical pathways, namely, SO 4 ∙ - and ∙OH, O 2 ∙ - , and non-radical pathway ( 1 O 2 ) involving BPA degradation. The abundant oxygen-containing groups, increased graphitization and mesopores of MBC800, and Fe 3+ /Fe 2+ conversion of Fe 3 O 4 particles facilitated PDS activation to produce reactive oxygen species . In addition, the superior electrochemical performance accelerated the electron transfer between the catalyst and PDS, promoting BPA degradation in the Fe 3 O 4 @MBC800/PDS system. More importantly, Fe 3 O 4 @MBC800 is resistant to environmental interference, including pH, anions, cations, and humic acid , and has good catalytic reusability and stability, which fulfills the requirements of engineering applications . Therefore, Fe 3 O 4 loaded on ball-milled biochar provides a convenient strategy for preparing environmentally friendly, economical, and efficient carbon-based catalysts to remove organic contaminants .