Optimizing the biosynthesis parameters of iron oxide nanoparticles using central composite design

•IONPs have been successfully biosynthesized using Moringa Oleifera leaves extract.•The combined effect of different parameters was studied by central composite design.•IONPs crystallite size was significantly influenced by the biosynthesis parameters.•An optimal crystallite size was obtained within the study range. In this study, Iron oxide nanoparticles (IONPs) were synthesized using a cost-effective and eco-friendly method, taking Moringa Oleifera leaves extract as a bio-reducer. Central Composite Design (CCD) of Response Surface Methodology (RSM) was employed to investigate the combined effect of three different synthesis parameters aiming to reach an optimum crystallite size of IONPs. The obtained nanoparticles were characterized by UV–Vis spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray analysis (EDX). The results have shown a significant effect of all the investigated parameters and their interactions on the crystallite size. Within the studied range, an optimal crystallite size has been achieved when the precursor concentration, reaction temperature, and annealing temperature were 0.03 M, 55°C, and 500°C respectively. The biosynthesized IONPs were assigned to the Hematite (α-Fe2O3) having a rhombohedral structure. Finally, a confirmatory run was carried out to verify the model adequacy, and consequently, approving the promising performance of RSM in optimizing the biosynthesis conditions of IONPs. [Display omitted]