Bio-Synthesis Of Zinc Oxide Nanoparticles And Zinc Oxide-Bentonite Nanocomposite Using Kosso (Hagenia Abyssinica) Aqueous Leaf Extract And Investigation Of Its Anti-Bacterial Activities

Abstract

The increment of bacterial infectious diseases and antibacterial drug resistance enhance the development of an appropriate antibacterial agent by dif erent methods from dif erent precursors. The purpose of this study was to synthesize a novel and environmental friendly zinc oxide-bentonite nanocomposites (ZnO-bentonite NCs) from Zinc acetate [Zn (CH3COO)2•2H2O using bentonite as solid support and Hagenia abyssinica (H. abyssinica) plant leaf extract as capping agents and used for antibacterial application. The reaction of Zn (CH3COO)2•2H2O with Na-bentonite and Aqueous leaf extract was ef ected at 80 0C, pH 12 and reaction time of 30 min. ZnO NPs were also synthesized using H. abyssinica leaf extract at 60 0C and pH of 12 for comparison of its antibacterial activity with the ZnO- bentonite NCs. Thermal analysis (TGA/DTA), X-ray dif raction (XRD), UV-Visible spectroscopy (UV-Vis), UV-Visible-Dif use reflectance spectroscopy (UV-Vis-DRS), Atomic absorption spectroscopy(AAS), Scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR) were used for the characterizations of thermal stability, crystalline structure, Optical properties, chemical composition, morphology and functional group of synthesized ZnO NPs and ZnO-bentonite NCs. TGA/DTA analysis result of ZnO NPs (1:2) and ZnO-bentonite NCs (1:1) confirmed that the synthesized NPs and NCs are stable above 450 0Cand 550 0C. XRD analysis result indicated that the synthesized ZnO NPs and ZnO phase in NCs have hexagonal Quartzite structure with an average crystalline size between 21-28 nm and 8- 22 nm respectively; except the ZnO impregnated in ZnO-bentonite (1:2) NCs with cubic structure. UV-Vis studies of ZnO NPs and ZnO-bentonite NCs revealed the characteristic peak in wavelength range 374-377 nm and 379 nm. UV-Vis-DRS characterization shows that the band gab of ZnO (1:1) and ZnO NPs (1:2) are 3.12 eV and 3.06 eV. It also confirms that ZnO-bentonite NCs (1:1 and 2:1) has band gab of 2.8eV and 3.1eV. FTIR spectra showed the presence of hydroxyl, carbonyl, alkyl, amide and other functional group in NPs and NCs. Antibacterial activity of uncalcined ZnO NPs-1:1 (ZOB) in all concentration ranges showed a greater zone of inhibition against both bacterial strains compared to claimed ZnO NPs. ZB2 (1:1) shows the better antibacterial ef icacy against both bacterial strains than ZB1 (2:1) due to the high dispersion of ZnO NPs in composite;