Effect of Nickel Nitrate Concentration on the Size of Nickel Oxide Nanoparticles Bio-synthesized by Artemisia herba-alba Aqueous Leaves Extract and Improving Their Antioxidant Activities

This work aims to investigate the effect of nickel nitrate concentration on the size and antioxidant activity of nickel oxide nanoparticles. For the first time Artemisia “ herba-alba ” leaves extract were employed to biosynthesize NiO NPs with four different nickel nitrate concentrations (0.01, 0.025, 0.05 and 0.075 M). Various analytical techniques were employed to study the properties of the obtained nanoparticles such as ultraviolet–visible (UV–Vis), X-ray diffraction (XRD), and Fourier transforms infrared spectroscopy (FTIR) analyses, SEM and EDX. Furthermore, the antioxidant activity of NiO NPs was investigated using total antioxidant capacity (TAC), DPPH· (2,2-diphenyl-1-picrylhydrazyl), and ferric ion reducing antioxidant power assay assays. The results have shown that the obtained NPs were assigned to a pure cubic NiO with an average size ranging between 7.49 and 10.7 nm. The results have also shown that both the size and antioxidant activity of NiO NPs are highly affected by nickel nitrate concentration. These findings can be used to control and optimize the antioxidant activity of NiO nanoparticles. Graphical Abstract