Mechanochemical Synthesis of Zinc Oxide Nanoparticles and their Antibacterial Activity against Escherichia Coli

Crystalline ZnO nanoparticles were synthesized by a mechanochemical method using zinc acetate dihydrate and sodium hydroxide as starting materials, and cetyl trimethylammonium bromide (CTAB) as a protective agent. Mechanochemical activation of the solid-state reaction was achieved at low temperatures in a rapid laboratory ball mill. A three-level full factorial experimental design was used to investigate the effect of milling time and surfactant ratio on ZnO crystallite size. The product powders were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The crystallite size of ZnO samples estimated from XRD is consistent with the SEM images and found to be less than 40 nm. The crystallite size of the ZnO decreased as the surfactant ratio increased. There is an optimal milling time of 60 minutes in order to obtain ZnO nanoparticles with the smallest average grain size. The antibacterial activity of the obtained products against Escherichia coli (E. coli) was examined, and the minimum inhibitory concentration value was 5 mg/mL. ZnO synthesized by this simple method can be considered potentially as an effective bactericidal agent.