Enhanced removal of urinary antibiotics via synergistic adsorption-catalysis by phosphorus-modified biochar-MoS₂/alginate hydrogel beads.

In response to ecological risks posed by antibiotic residues in urine resource utilization, this study innovatively developed phosphorus-modified Phragmites biochar-molybdenum disulfide/alginate composite hydrogel beads (MPBC) for synergistic adsorption and catalytic degradation of typical antibiotics diclofenac (DCF) and oxytetracycline (OTC). Orthogonal optimization yielded MPBC with a hierarchical mesoporous structure (348.66 m²/g specific surface area) and abundant phosphorus-containing groups (O-P, C-P-O), achieving adsorption capacities of 64.23 mg/g (DCF) and 58.74 mg/g (OTC)-3-10 times higher than commercial coconut biochar hydrogel beads. Mechanistic analysis revealed hydrogen bonding, π-π stacking, and O-P group interactions as dominant adsorption drivers, supported by DFT calculations showing enhanced interfacial binding energy (-48.41 kJ/mol). MPBC activated persulfate (PMS) for in-situ regeneration, achieving > 92 % degradation within 1 h (15 mM PMS), primarily via non-radical pathways (·O₂⁻ and ¹O₂). Continuous flow experiments demonstrated stable operation for > 1500 bed volumes, with > 84 % adsorption capacity retention after three regeneration cycles. Notably, MPBC selectively retained > 96 % of nitrogen, phosphorus, and potassium nutrients in urine. This work provides a dual-functional material design strategy for high-efficiency antibiotic removal, recyclability, and nutrient recovery in urine resource utilization.