Fe₃O₄/GO/LDHs peroxidase-mimicking nanocomposite for synergistic adsorption and degradation of tetracyclines

The residues of tetracycline antibiotics (TCs) in aquatic environments have led to pressing environmental issues, necessitating the development of efficient removal technologies. In this study, we constructed an adsorption-degradation synergistic system based on Fe₃O₄ nanoparticles/graphene oxide/layered double hydroxides (Fe₃O₄/GO/LDHs) for the removal of TCs from water. This Fe₃O₄/GO/LDHs composite ingeniously combines the adsorption advantages of both GO and LDHs: GO serves as a growth substrate for LDHs, effectively preventing the LDHs from agglomerating into bulk masses, while LDHs also inhibit the interlayer stacking of GO. This leads to enhanced specific surface area of up to 581.7 m 2 /g, establishing a robust structural foundation for efficient adsorption. The incorporation of Fe₃O₄ nanoparticles not only endows the material with excellent magnetism for convenient magnetic separation and recovery but also utilizes its peroxidase-like activity to achieve catalytic degradation. The equilibrium adsorption capacities of Fe₃O₄/GO/LDHs for tetracycline, oxytetracycline, and chlortetracycline reached 676.5 mg/g, 814.1 mg/g, and 808.1 mg/g, respectively, primarily driven by electrostatic, π-π and complexation interactions. In the presence of H₂O₂, Fe₃O₄/GO/LDHs activating H₂O₂ to generate reactive oxygen species, achieving over 90% degradation rate within 1 h, demonstrating strong catalytic capability. Integrating adsorption with in-situ degradation, Fe₃O₄/GO/LDHs functions as a network of micro-reactor factories, rapidly concentrating pollutants at catalytic active sites and creating a high-local-concentration microenvironment that dramatically accelerates catalytic reactions, thereby enhancing overall degradation efficiency. This study advances the development of adsorption-degradation bifunctional nanozymes for water purification.