A spore-derived Fe2P/biochar composite for efficient tetracycline degradation: Reaction mechanism investigation, antibacterial activity elimination and antibiotic resistance risk mitigation

Fe 2 P/N-doped biochar (FeBC900) was derived from Aspergillus niger spores. • FeBC900 showed high PDS activation, broad pH adaptability and low Fe leaching. • Surface-bound radicals and 1 O 2 served as dominant reactive species in TC removal. • The FeBC900/PDS system reduced TC antibacterial activity and resistance induction. The widespread utilization of tetracyclines (TCs) has resulted in their continuous discharge and dissemination into aquatic environments, thereby accelerating the spread of antibiotic resistance genes, which threaten the natural ecosystem and human health. To address tetracycline pollution in aquatic environments, the Fe 2 P/biochar (FeBC900) composite synthesized from Aspergillus niger spores was used to activate peroxydisulfate (PDS) for TC degradation. The FeBC900 composite preserved the pumpkin-like hollow structure of spore, with Fe 2 P nanoparticles tightly embedded and dispersed in the spore-derived carbon matrix. The excellent physicochemical properties of FeBC900, such as large specific surface area, well-developed hierarchical porous structure, high density of surface defects, and abundant reactive sites (pyridinic N, graphitic N, and Fe 2 P nanoparticles), ensured its effective activation of PDS, thus leading to the efficient TC removal (>99%) within 30 min under optimized reaction conditions. Attributed to the superior structural stability of FeBC900 with the effective immobilization and encapsulation of Fe 2 P nanoparticles, FeBC900/PDS reaction system presented broad pH adaptability and low Fe ions leaching. Quenching experiments combined with electron paramagnetic resonance (EPR) identified surface-bound radicals and 1 O 2 as the predominant reactive oxygen species responsible for TC degradation. Impressively, the antibacterial activity test and bacterial resistance mutation test confirmed that the ecological risk of the treated TC solution was significantly reduced, particularly in terms of its induction of bacterial antibiotic resistance. Overall, this work provides a practical solution to mitigate TC pollution and the consequent risk of bacterial antibiotic resistance. Download: Download high-res image (157KB) Download: Download full-size image