Optimizing CuO nanoparticle synthesis via walnut green husk extract utilizing response surface methodology

Fabrication of CuO nanoparticles (NPs), popular nanostructures, through green synthesis using plant extracts, offers distinct advantages, fostering their broad application. In this study, CuO NPs were synthesized utilizing walnut green husk aqueous extract, and their production was optimized by investigating the impact of three factors: extract volume, copper acetate concentration, and reaction time, employing response surface methodology (RSM) with a face-centered central composite design (CCD). A statistically significant and adequate linear model (p-value <0.0001, R2: 0.98) effectively described the influence of these factors on the CuO NPs production, with the extract volume exerting the highest impact, followed by copper acetate concentration, and reaction time demonstrating the least impact. The NPs, produced under conditions of 1 mM salt concentration and 1 mL extract per 10 mL reaction over 1 h, were characterized. Field Emission Scanning Electron Microscopy (FESEM) and Ultraviolet–Visible (UV–vis) spectroscopy revealed nearly spherical NPs with an average size of 54.03 nm and a surface plasmon resonance (SPR) peak at 194 nm. Energy Dispersive X-ray (EDX) analysis and Fourier-Transform Infrared (FTIR) spectroscopy confirmed the elemental composition and the presence of extract biomolecules in the NP coating. The fabricated NPs exhibited an amorphous and monodisperse nature, with an average hydrodynamic diameter of 82.61 nm.