Vinasse-derived magnetic porous Fe-biochar for synergistic adsorption and non-radical oxidation of bisphenol A: Mechanisms and applications

Valorizing waste vinasse into Fe-doped multifunctional biochar offers an efficient route to boost peroxymonosulfate (PMS) activation and improve wastewater purification. In this study, a magnetic porous Fe-doped vinasse biochar (FVB 700 ) was synthesized via co-pyrolysis of vinasse and ferrous oxalate. The obtained material exhibited a synergistic effect between adsorption and PMS catalytic activation for efficient bisphenol A (BPA) removal. Specifically, FVB 700 , with primary iron species (Fe 0 , Fe 3 C, and Fe 3 O 4 ), rapidly adsorbed BPA through monolayer chemisorption, and the adsorbed BPA was subsequently degraded via PMS activation. Quenching experiments and EPR analysis identified singlet oxygen ( 1 O 2 ) as the dominant nonradical species responsible for BPA degradation in the FVB 700 /PMS system. Density functional theory analysis revealed Fe 3 C as the main catalytic center, anchoring PMS via its terminal -SO 4 oxygen and reacting with another adsorbed HSO 5 − to generate 1 O 2 . The FVB 700 /PMS system retained high performance across a wide pH range (4-11), resisted common water matrix interferents (Cl − , NO 3 − , HCO 3 − , H 2 PO 4 − , and humic acid), and achieved 78.9 %-90.2 % BPA removal in actual water bodies (tap water, groundwater, and pharmaceutical wastewater). Moreover, in a continuous-flow fixed-bed reactor, it maintained over 90 % BPA removal for 8 days, underscoring its long-term stability and practical applicability. Degradation pathway analysis and ECOSAR prediction showed detoxification of BPA into low-hazard intermediates. This study presents an eco-friendly, “waste-to-resource” strategy that integrates Fe-doping with an adsorption-oxidation synergy for the sustainable and efficient remediation of organic contaminants in water.