Next-generation Ni-doped CoFe2O4@SiO2-NH2-gallic acid nanocomposites: Synergistic effects of functionalization for advanced dye removal and antibacterial applications

• NiCF@SiO 2 -NH 2 -GA shows significant efficiency for cationic and anionic dyes. • NiCF@SiO 2 -NH 2 -GA achieves over 98% removal of dyes in just 30 min. • NiCF@SiO 2 -NH 2 -GA has effective across a range of temperatures, enhancing viability. • Mesoporous structure increases active sites for superior dye binding. This study presents the synthesis of nickel-doped CoFe₂O₄ (NiCF) nanoparticles, which were coated with silica (SiO₂), functionalized with amino groups (NH₂), and decorated with gallic acid (GA). The resulting NiCF@SiO₂-NH₂-GA nanocomposite demonstrated a significant reduction in particle size, from an average of 9-27 nm to 4.88 nm, thereby enhancing the capacity for dye adsorption. The surface area increased from 13.985 m²/g to 30.235 m²/g, and the pore volume increased from 0.055 cm³/g to 0.13 cm³/g, indicating improved adsorption potential. N₂ adsorption isotherms confirmed the presence of mesopores with an average diameter of 5.9998 nm, supporting efficient dye capture. Maximum adsorption capacities were recorded as 99.07 mg/g for Methylene Blue, 85 mg/g for Rhodamine B, 84.27 mg/g for Methyl Red, and 96.92 mg/g for Methyl Orange, with rapid kinetics described by the pseudo-second-order model. Isotherm analysis indicated a better fit for the Langmuir and Sips models. Cytotoxicity assessments via MTT assays revealed no adverse effects on cell viability after 24 and 48 h, even at high concentrations. The nanocomposites demonstrated stability and efficiency over five regeneration cycles, establishing them as a promising biocompatible solution for simulated wastewater treatment applications. Moreover, the antibacterial activity of nanocomposites was evaluated against pathogenic microorganisms, demonstrating significant efficacy, particularly when combined with Imipenem, against Gram-negative bacteria like Klebsiella pneumonia.