Nanoconfinement-Tailored Surface-Bound Singlet Oxygen Enhances Antibiotics and Antibiotic Resistance Gene Removal at Soil Heterogeneous Interfaces

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-NCFe 0 ). Nanoconfinement promotes Fe–C hybridization, shifting the d-band center and reducing the work function of SM-NCFe 0 to enable ultrafast electron transfer to peroxydisulfate (PDS), elongating its O–O bond and favoring surface-bound singlet oxygen ( 1 O 2 ) 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., nFe 0 /PDS, 80.2%). Over 40 days in heterogeneous soil, the SM-NCFe 0 /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), nFe 0, nano-Fe x O y ). By balancing superior catalysis, affordability, and ARGs mitigation, SM-NCFe 0 heralds an eco-friendly, cost-effective paradigm for tackling antibiotic-contaminated soils and stemming resistance dissemination.