Study On The Preparation And Antibacterial Activity Of Nano-ZnO And ZnO-Ag Heterostructure

With the development of social economy and the improvement of life level, there is an increasing concern about health problem. Germs are absent nowhere and a variety of infectious diseases cause a great damage to people's life and property, so the research on the antibacterial materials is significant. Nano-ZnO antibacterial is attracting more and more attention, since it can overcome the disadvantages of silver and TiO2 antibacterial material, such as the problems of changing color and needing ultraviolet radiation, etc.The preparation process of nano-ZnO was studied, and the effect of experiment parameters on crystal size was discussed. Then, ZnO-Ag nanoheterostructures were prepared on the base of nano-ZnO. The prepared samples were characterized by XRD and TEM. Finally the antibacterial activities of nano-ZnO, ZnO-Ag nanoheterostructures and antibacterial wood floor were tested respectively.Nano-ZnO powders were prepared by direct chemical precipitation method. By doing research on the relationship between crystal size and experiment parameters including the molar ratio of reactants, reaction time, reaction temperature, concentration of Zn2+ and the amount of sodium citrate, We found the following experiment parameters: the molar ratio of Zn(NO3)2 to NaOH is equal to 1:2, reaction time is one hour, reaction temperature is 60℃, concentration of Zn2+ is 0.05M and the amount of sodium citrate is 0.35g. The XRD results showed that: diffraction peaks are in accordance with the standard card PDF 80-0074 of ZnO, which indicates that the samples are ZnO. The peaks are high and keen, which indicates that the prepared ZnO have a good crystal performance. The TEM photos indicate that the morphology of ZnO grains can be divided into two kinds, one is ball-like and the other is rod-like. The mean diameters of ZnO grains are between 20nm and 40nm while the length of rod -like ZnO grains are approximately 200nm.Based on the preparation process of nano-Zn, ZnO-Ag nanoheterostructures were prepared using the same method. The forming mechanism of ZnO-Ag nanoheterostructures was also discussed. The XRD curves of the prepared samples show that: With the increasing amount of Ag, the characteristic diffraction peak of Ag at 38.14°(111) is stronger. The TEM photos of the samples indicate that the morphology of ZnO-Ag heterostructure grains is rod-like. The mean diameters of ZnO-Ag heterostructure grains ranged from 40nm to 60nm and the aspect ratio is approximately 8:1. Minimal Inhibitory Concentration of nano-ZnO particles and ZnO-Ag nanoheterostructures were tested using nutrient broth dilution method. The results are as following: MIC of pure nano-ZnO is 100ppm and MIC of ZnO-Ag heterostructure Ag (wt %) =0.2wt%, 0.5 wt%, 1.08 wt% are 50ppm, 25ppm and 12.5ppm respectively. The antibacterial wood floor were made by adding nano-ZnO powders into the wearable paper of laminate wood floor .The antibacterial tests showed that the antibacterial activity of the antibacterial wood floor increase with the increasing amount of ZnO . Sterilizing efficiency of the antibacterial wood floor was beyond 99.9% when the concentrations of ZnO were up to 10000 ppm.