Magnetic biochar derived from penicillin fermentation residue for efficient penicillin G sodium adsorption: kinetics, degradation mechanism, and simulations.

The escalating environmental contamination from penicillin G sodium (PGNa) misuse poses significant threats to ecosystem integrity and public health, necessitating advanced remediation strategies. In this study, porous magnetic biochar (SAMB) was derived from penicillin fermentation residues through coupled covalent precipitation and acid-alkali modification (98.3 % PGNa removal within 2 h). Mechanistic investigations combining density functional theory and liquid chromatography-mass spectrometry revealed that PGNa was degraded by β-lactam ring cleavage followed by decarboxylation, decarbonylation, demethylation, and deamidation. Regeneration experiments showed that SAMB still maintained 33.8 % PGNa removal efficiency after five cycles. In addition, ecotoxicological assessment using the ECOlogical Structure Activity Relationship predictive model confirmed substantially reduced aquatic toxicity of resultant intermediates. Conversion of penicillin residue into magnetic biochar SAMB simultaneously achieves waste resource utilization and effective PGNa removal, providing dual environmental benefits for antibiotic pollution control and circular economy practices.