Zn1-xMgxO nanocomposites were synthesized by a modified sol-gel method. The effect of increasing Mg content on structural, optical properties, and antibacterial activity was studied. The structure and physical properties of the Zn1-xMgxO nanocomposites were characterized by thermogravimetric (TG) analysis, Fourier-transform infrared spectroscopy (FT-IR), X-Ray Diffraction (XRD), and transmission electron microscope (TEM). The optical properties were investigated by UV-visible spectroscopy and Photo luminesce spectra (PL). The thermal properties and the weight stability were studied for the samples using TG-Analysis to determine the best annealing temperature at 550 °C. The XRD result confirms that clear indications for segregation into a hexagonal and a cubic phase are found for samples having magnesium content between 0.2 ≤ x ≤ 0.8. According to Scherer's formula, the average particle size of the synthesized nanocomposites is in the range of 16.32-25.56 nm. TEM images showed hexagonal, irregular, and spherical shapes. The calculated band gap energies (Eg) of the Zn1-xMgxO nanocomposites were changed from 3.18 to 3.31 eV by increasing Mg concentration in the Zn1-xMgxO nanocomposites. The XRD and UV-vis analysis results indicated that the physical characteristics of Zn1-xMgxO nanocomposites were dependent on increasing the incorporation of Mg2+ ion concentration. The antibacterial assessment illustrated that the ZnO-MgO nanocomposites showed excellent antibacterial activity, the inhibition zoon increases from 12 mm for pure ZnO to 15 mm for Zn1-xMgxO nanocomposites with Mg ratio (x=0.4). The result concluded that Zn1-xMgxO nanocomposites have significant potential for antibacterial applications.

The present work employs Ocimum Basilicum extract as a bio-reducing and a capping agent to synthesize zinc oxide nanoparticles (ZnO NPs) at different temperatures (30 o C, 6 0 o C, and 90 o C) in an efficient, simple, and environmentally friendly method (green synthesis), as well as their use in treating wastewater and antibacterial activity. The samples have a hexagonal structure confirmed by the X-ray Diffraction (XRD), and by using the Scherrer equation, the particle size was calculated. UV-Visible diffuse reflectance spectroscopy reveals the characteristic absorbance peak at 373 nm and gives the band gap nearly 3.23 eV for synthesized (ZnO NPs) due to the quantum confinement effect. Transmission electron microscopy (TEM) shows spherical-shaped particles. The products (ZnO-NPs) have a good effect on antibacterial activity against different types of bacteria. After 7 hours, the degradation rate of methylene blue (MB) dye by synthesized ZnO-NPs as a photocatalyst is 92.28 % from ZnO NPs synthesized at 30 oC.