The role of NaOH content, grinding time, and drying temperature in controlling the shape and size of nano ZnO synthesized by a green chemistry approach

Abstract

Zinc oxide (ZnO) has been widely exploited in different technological applications in virtue of its unique physical and chemical qualities. This study was designed to prepare ZnO nanorods for diagnostic applications using a simple, low cost, and solvent-deficient method with clarifying the effect of different experimental parameters on the shape and the size of the ZnO product. Under different experimental conditions, the synthesis was performed via a solid-state reaction of zinc sulfate and sodium hydroxide using the grinding method. The purity of nano ZnO products was investigated by X-ray diffractometer (XRD) while the size and the shape were demonstrated by high- resolution transmission electron microscopy (HRTEM). The XRD results confirmed the production of pure ZnO nanocrystals. The HRTEM micrographs illustrated the preparation of a mixture of nanospheroids and nanorods particles, nanorods with minor nanospheroids particles, and long nanorods particles when the applied mole ratio of (ZnSO4.7H2O: NaOH) was (1:2), (1:4), and (1:8) respectively. Our findings confirmed the vital role of NaOH in controlling the shape and the particle size of nano ZnO. Since ZnO nanorods can be easily prepared under mild environmentally friendly conditions, it is proposed that the described experimental conditions can be adapted for large scale production.