Fe2P/N-doped biocarbon composite derived from mycelial pellet for bisphenol AF removal through peroxymonosulfate activation

In this work, microorganism of Phanerochaete chrysosporium with iron-tolerating and accumulating abilities was cultivated and harvested as mycelial pellets, which could serve as a sustainable and environmental-friendly precursor for iron phosphide/N-doped biocarbon composite preparation. Through one-step pyrolysis process, the inherent Fe and P elements in mycelial pellet enabled the formation of well crystallized Fe2P particles, loading on N-doped biocarbon matrix. Benefiting from the porous structure, high specific surface area, N doping-induced defects and C=O groups of biocarbon, as well as the good electron-donating property of Fe2P, the as-obtained Fe2P/BC composite performed well for bisphenol pollutant (e.g., BPAF) removal through peroxymonosulfate (PMS) activation. Specifically, almost complete BPAF removal was achieved within 30 min adsorption and 10 min catalysis process with an apparent reaction rate constant of 0.486 min(-1). The good crystallinity and protective carbon layer wrapping on Fe2P enabled the wide pH adaptability and low iron leaching of Fe2P/BC in catalytic reaction. Inorganic anions and humic acid brought only slight inhibition for BPAF removal, which could be overcome by prolonging reaction time to 30 min. Further mechanism studies indicated that reactive oxygen species, e.g., SO4-center dot, (OH)-O-center dot and O-1(2) were generated through both radical and non-radical pathways and contributed to BPAF degradation. After treatment by Fe2P/BC-PMS system, the total organic carbon (TOC) of original BPAF solution (20 mg L-1) was reduced by 51.6%. Fortunately, the residual degradation intermediate products showed much reduced ecotoxicity in both predicted (ECOSAR program) and experimental results (growth inhibition test using Raphidocelis subcapitata as ecological indicator).