Green Synthesis of Zinc Oxide Nanoparticles Using Clove Extract by Three Different Heating Methods and Evaluation of their Properties

In the present study, zinc oxide nanoparticles (ZnO NPs) have been synthesized using hydroalcoholic clove extract and three accelerated heating methods namely, hydrothermal (at 121 °C and 1.5 bar), microwave irradiation (power of 800 W for 3 min) and conventional heating using a heater and stirrer (at 150 °C for 2 h). Characteristics of the  prepared clove extract and synthesized ZnO NPs have been evaluated using GC-MS, XRD and SEM analyses and their antioxidant and antibacterial activities have been measured using DPPH and agar diffusion techniques.   GC-MS analysis indicated that the provided extract had contained two main bioactive compounds of Eugenol and β-caryophyllene, which both of them are natural reductant agents. In order to synthesis ZnO NPs, 4 g of zinc nitrate and 20 mL of the provided clove extract had been mixed together  and after heating the mixture solutions using three different heating methods,the solutions have been placed into the laboratory furnace adjusted at 400°C for 2h to result in pale yellow powder. Obtained results indicated that the synthesized ZnO NPs using microwave, autoclave and heater and stirrer, had particle size of 45, 50 and 52 nm, antioxidant activity of 89, 85 and 80% and methylene blue degradation of 79, 70 and 66%, respectively. Furthermore, results indicated that the synthesized ZnO NPs have high antibacterial activity against both bacteria strains of Escherichia coli and Staphylococcus aerous.