Fe-MOFs-derived Fe3O4-doped biochar from waste chopsticks: a novel catalyst for tetrabromobisphenol a degradation via peroxymonosulfate activation

Biochar production has emerged as a highly effective strategy for waste-to-resource conversion. In this study, biochar derived from waste chopsticks was doped with Fe3O4 using MIL-100 (Fe)-a metal-organic framework (MOF)-was synthesized at various pyrolysis temperatures and designated as Fe3O4@BC. The catalyst was employed to activate peroxymonosulfate (PMS) for the removal of tetrabromobisphenol A (TBBPA), a widely used brominated flame retardant (BFR). Remarkably, the Fe3O4@BC/PMS system achieved 98 % TBBPA removal within 30 min. The exceptional catalytic performance of Fe3O4@BC was attributed to the uniform dispersion of iron oxides and the abundance of oxygen-containing functional groups on the biochar surface. The underlying mechanism of TBBPA degradation was systematically investigated, revealing two distinct degradation pathways and identifying 18 by-products using liquid chromatography-mass spectrometry (LC-MS) and density functional theory (DFT) analysis. Furthermore, scavenger tests and electron paramagnetic resonance (EPR) spectra demonstrated that superoxide radicals (O2 & sdot;-) played a critical role in TBBPA degradation within the catalyst/ PMS system. This study highlights the immense potential of biochar derived from waste chopsticks as an ecofriendly and efficient catalyst. Key advantages include the utilization of solid waste, reduced toxicity of degradation intermediates, and effective PMS activation for the degradation of BFRs.