**2.2. Preparation and size analysis of zinc nanoparticles**

The method described by Fadeyibi et al. [10] was used to prepare the zinc nanoparticles. The method involves mixing two homogeneous solutions prepared separately. The first solution was prepared by adding 30 mL of distilled water to 20 mL of triethanolamine with constant stirring while adding 2 mL (100 drops) of ethanol in drop wise. The second solution was prepared by adding 5.39 g of zinc acetate di-hydrate to 50 mL distilled water with continuous stirring, to form a 0.5 M solution. The two solutions were mixed together in 500 mL beaker and a solution of ammonium hydroxide and 10 mL distilled water were added (in drop wise). The mixture was left undisturbed for 30 minutes to form a white bulky solution, which was washed 8–10 times with distilled water and filtered in a filter paper. The resulting residue was dried in the oven at 95°C for 8 hours. Also, the zetasizer equipment (version 7.01) was used to carry out size analysis of the synthesised zinc particles to establish their size range in nanometre. The tests were carried out at the Centre of Genetic Engineering and Biotechnology of the Federal University of Technology Minna, Nigeria.
