Synthesis Zinc Oxide Nanoparticles Using Zinc Chloride, Zinc Nitrate Hexahydrate And Zinc Acetate Dihydrate Precursors For Antibacterial Applications

Abstract

In this study, the ZnO nanoparticles were synthesised by using salt precursors ZnCl2, Zn(NO3)2.6H2O and Zn(CH3COO)2.2H2O via a wet chemical method and calcinated at 200 , 300 and 400 0c respectively for antibacterial applications. Also, the synthesised ZnO NPs were modified using biologically active compound caffeine. The average crystallite size of the ZnO Nps determined by XRD was about 31.86 nm and 28.09 nm for samples synthesised by Zn(CH3COO)2.2H2O and Zn(NO3)2.6H2O respectively. The shape of ZnO NPs synthesised from Zn(NO3)2.6H2O, ZnCl2 and Zn(CH3COO)2.2H2O were agglomerated flower-like spherical and rod-like respectively. The variation in size and shape of ZnO NPs is due to the difference in precursors and calcination temperature. The UV-Vis absorption peak of the ZnO NPs was observed at 278 nm, 374 nm and 378 nm for ZnCl2, Zn(NO3)2.6H2O and Zn(CH3COO)2.2H2O respectively. The vibrational phonon of ZnO observed at 507cm-1, 433 cm-1 and 507 cm-1 for precursors of ZnCl2, Zn(NO3)2.6H2O and Zn(CH3COO)2.2H2O respectively confirms the successful production of ZnO nanoparticles. The excitation wavelength of the ZnO NPs synthesised from the precursors ZnCl2, Zn(NO3)2.6H2O and Zn(CH3COO)2.2H2O were performed at 275 nm, 355 nm and 290 nm respectively. The ZnO NPs showed both an ultraviolet emission band at 325nm, 392 nm and 435 nm due to the electronic transition from conduction band edge to valence band, and visible emission band at 455 nm, 466 nm and 469 nm due to defects that are related to deep level emissions for ZnCl2, Zn(CH3COO)2.2H2O and Zn(NO3)2.6H2O respectively. The synthesised ZnO NPs were applied for antibacterial activity on S.aureus and E.coli bacteria using disc diffusion agar method. All the three ZnO Nps showed admirable antibacterial activity on S.aureus than the standard antibiotic drugs. Among the three, the ZnO NP synthesised from the precursor ZnCl2 showed excellent antibacterial activity.