A “waste-treating-waste” strategy of upcycling residual lithium from spent battery recycling waste into functional adsorbents for sulfonamide removal

The increasing accumulation of spent lithium-ion batteries (LIBs) poses significant environmental challenges, while the contamination of water bodies by sulfonamide antibiotics remains a pressing global concern. This study presents an innovative “waste-treating-waste” strategy by transforming spent LIBs into a high-performance adsorbent (LEP/AC) for sulfamethazine (SMZ) removal, simultaneously addressing battery waste recycling and antibiotic pollution challenges. Through response surface methodology optimization, the composite achieved enhanced surface area (848 m²·g⁻¹) and well-dispersed Fe–P–O active sites, enabling efficient SMZ adsorption (91.39%) via synergistic chemisorption (Fe–P–O coordination/hydrogen bonding) and physisorption (π–π interactions). Thermodynamic analysis confirmed the spontaneous (ΔG⁰ = −7.550 kJ/mol) and endothermic (ΔH⁰ = 28.502 kJ/mol) nature of adsorption, while mechanistic studies using XPS and DFT calculations revealed atomic-level interactions between SMZ and the adsorbent. The material demonstrated robust performance in real water matrices (>80% efficiency) despite competing ions and humic acid, showcasing its dual environmental benefits: upcycling hazardous battery waste into functional materials while providing a cost-effective solution for antibiotic-contaminated water remediation. This work establishes a sustainable circular economy model for integrated waste management and water treatment. © 2026 Elsevier B.V.