Synthesis and evaluation of a Ni-H2bpda/Fe3O4 nanocomposite with high tetracycline adsorption capacity and broad-spectrum antibacterial activity

In this study, a novel nanocomposite based on Fe 3 O 4 , nickel acetate, and the organic ligand Benzophenone-4,4-dicarboxylic acid (H 2 bpda) was synthesized and thoroughly characterized. The coexistence of the magnetic phase and the Ni-H 2 bpda complex resulted in a stable, recoverable material exhibiting high efficiency in removing tetracycline from aqueous solutions. Key operational parameters, including adsorbent dosage, initial pollutant concentration, pH, temperature, and contact time, were systematically investigated to determine the optimal adsorption conditions. Kinetic analysis indicated that the adsorption process followed a pseudo-second-order model, while isotherm studies showed a better fit with the Langmuir model, suggesting uniform adsorption sites on the nanocomposite surface. Beyond its high tetracycline adsorption capacity, the synthesized nanocomposite demonstrated significant antibacterial activity against a wide range of Gram-positive and Gram-negative standard strains, wastewater-isolated bacteria, and pathogenic aquatic microorganisms. This behavior highlights the synergistic effect between the inorganic and organic Ni-based components in generating an active surface capable of inhibiting microbial growth. The combination of effective adsorption, reusability, and broad-spectrum antibacterial properties makes the Ni-H 2 bpda/Fe 3 O 4 nanocomposite a promising candidate for water purification and microbial contamination control.