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 (FVB700) 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, FVB700, with primary iron species (Fe0, Fe3C, and Fe3O4), rapidly adsorbed BPA through monolayer chemisorption, and the adsorbed BPA was subsequently degraded via PMS activation. Quenching experiments and EPR analysis identified singlet oxygen (1O2) as the dominant nonradical species responsible for BPA degradation in the FVB700/PMS system. Density functional theory analysis revealed Fe3C as the main catalytic center, anchoring PMS via its terminal -SO4 oxygen and reacting with another adsorbed HSO5- to generate 1O2. The FVB700/PMS system retained high performance across a wide pH range (4-11), resisted common water matrix interferents (Cl-, NO3-, HCO3-, H2PO4-, 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.