Nanoconfinement-Tailored Surface-Bound Singlet Oxygen Enhances Antibiotics and Antibiotic Resistance Gene Removal at...

Soil serves as a major sink for antibiotics from diverse anthropogenic sources, fueling the proliferation of antibiotic resistance genes (ARGs) and endangering public health and ecosystems. Although persulfate-based in situ chemical oxidation (PS-ISCO) offers promise for soil remediation, its efficacy is curtailed by nonselective radical scavenging and limited access to adsorbed antibiotics. Herein, we introduce a sustainable strategy leveraging recovered Enteromorpha waste to fabricate superfine monodisperse biochar-confined zerovalent iron nanocrystals (SM-NCFe⁰). Nanoconfinement promotes Fe-C hybridization, shifting the d-band center and reducing the work function of SM-NCFe⁰ to enable ultrafast electron transfer to peroxydisulfate (PDS), elongating its O-O bond and favoring surface-bound singlet oxygen (¹O₂) over radical pathways. This nonradical mechanism delivers exceptional tetracycline removal from soil (99.6%) with a rate constant (0.15 min^-1) 3.2- to 7.5 times higher than that of traditional radical-based systems (e.g., nFe⁰/PDS, 80.2%). Over 40 days in heterogeneous soil, the SM-NCFe⁰/PDS system eradicated both dissolved and adsorbed antibiotics almost nearly completely, while significantly reducing the expression of typical ARGs by 48.8-72.2% at substantially lower oxidant doses compared to benchmarks (Fe(II), nFe⁰, nano-Fe_xO_y). By balancing superior catalysis, affordability, and ARGs mitigation, SM-NCFe⁰ heralds an eco-friendly, cost-effective paradigm for tackling antibiotic-contaminated soils and stemming resistance dissemination.