Magnetic and antibacterial properties of substituted cobalt spinel ferrite nanocomposites synthesized via henna green microwave hydrothermal method.

A novel henna-green/microwave-assisted hydrothermal method was applied to synthesize cobalt-manganese spinel ferrite nanocomposites. This eco-friendly approach, utilizing henna extract as a capping agent, combined with a microwave-assisted hydrothermal technique, offers advantages such as environmental sustainability, time, and energy efficiency. Examined parameters included pH (10 ± 1), temperatures (175 ± 25 °C), durations (15, 30 ± 15 min), and forty milliliters of henna extract prepared with varying henna quantities (five, ten, or fifteen grams per hundred milliliters of water). Post-optimization, various substituents like nickel and chromium were explored. Samples were calcined at 500 °C, 700 °C, and 900 °C, and analyzed using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and magnetic property assessments. XRD revealed a cubic face-centered spinel ferrite and hematite structure. SEM and TEM showed diverse morphologies (rod-like, flower-like, polygonal) influenced by synthesis conditions and substituents. XPS confirmed Co, Mn, Ni, Fe, and Cr presence in the spinel lattice. The nanocomposites exhibited ferromagnetic behavior with saturation magnetization (M) values from 23.53 to 55.15 emu/g. Chromium substitution showed the best antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans. This study highlights the potential of the henna-green/microwave-assisted hydrothermal method for controlled synthesis of substituted cobalt spinel ferrite nanocomposites with tunable properties for various applications.