A multifunctional magnetic graphene oxide/NH₂-UiO-66(Zr)/sodium alginate nanocomposite for efficient tetracycline adsorption, antibacterial activity, and practical application in real water matrices.

A magnetic porous nanocomposite was synthesized and characterized for the efficient removal of tetracycline (TC), a broad-spectrum antibiotic of growing environmental concern due to its persistence in aquatic systems and its role in propagating antibiotic resistance genes. The nanocomposite, designated GO/NH₂-UiO-66/SA@Fe₃O₄, integrates graphene oxide (GO), amino-functionalized UiO-66(Zr) metal-organic framework (MOF), and magnetite nanoparticles (Fe₃O₄) within a sodium alginate (SA) hydrogel matrix. Structural and physicochemical properties were elucidated using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating-sample magnetometry (VSM), and thermogravimetric analysis (TGA). Process optimization was conducted via response surface methodology (RSM) employing a central composite design (CCD). The derived optimal conditions, pH 5.5, contact time of 44 min, adsorbent dose of 1.0 g L-1, and initial TC concentration of 10 mg L-1, yielded a maximum TC removal efficiency of 98.5%. Equilibrium adsorption data were best described by the Sips heterogeneous isotherm model, and kinetic behavior was most accurately captured by the double-exponential model, indicating a complex, multi-mechanism adsorption process. The nanocomposite exhibited a Langmuir maximum adsorption capacity of 161.4 mg/g, and excellent regeneration performance, retaining over 80% removal efficiency across ten consecutive adsorption-desorption cycles. Antibacterial assays confirmed significant inhibitory activity against both Escherichia coli and Staphylococcus aureus. Under optimized conditions, application to river water containing multiple coexisting interferents achieved 89.34% TC removal, underscoring the practical applicability of the adsorbent. Collectively, these findings establish GO/NH₂-UiO-66/SA@Fe₃O₄ as a multifunctional, recyclable nanocomposite with strong adsorptive performance and intrinsic antibacterial activity, offering a promising platform for sustainable remediation of antibiotic-contaminated water.