Ultrahigh-efficiency and synchronous removal of microplastics-tetracycline composite pollutants via S-scheme core-shell magnetic nanosphere

Abstract

Composite pollution in aquatic environments has become a critical challenge, with emerging pollutants like antibiotics and microplastics (MPs) posing significant ecological risks. The interaction between antibiotics and MPs complicates treatment processes and underscores the need for targeted removal strategies. This study focused on a novel S-scheme core-shell magnetic nanosphere, Fe₃O₄@TiO₂-C₄N, combining TiO₂ and C₄N to form a heterojunction that enhances photocatalytic performance. The S-scheme heterojunction improves redox ability, enabling efficient degradation of composite pollutants under light irradiation. After 12 h reaction, Fe₃O₄@TiO₂-C₄N achieved 97.3 % removal for polyethylene (PE) MPs and 96.0 % removal for tetracycline (TC), surpassing existing TiO₂-based catalysts. Moreover, Fe₃O₄@TiO₂-C₄N demonstrated excellent magnetic recyclability rate of 77.07 %, enabling easy catalyst recovery and reuse. Meanwhile, Fe₃O₄@TiO₂-C₄N outstands on TC removal at an optimal concentration (200 mg L⁻¹). Notably, MPs in composite pollution scenarios showed higher removal rates than individual pollutants. This study highlights the powerful role of Fe₃O₄@TiO₂-C₄N as a promising photocatalyst for the joint degradation of multiple composite pollutants in aquatic environment, providing an innovative solution for addressing water pollution challenges. Furthermore, its real-world application potential is demonstrated by its efficient recovery, long-term stability, and compatibility with existing water treatment systems, paving the way for large-scale environmental remediation technologies.