Preparation Of Bismuth Tungstate Composites And Their Visible And Photocatalytic Antibacterial Properties

With the improvement of people’s living standards, people paid more and more attention on the living and sanitary conditions, and therefore various antibacterial material emerged. Photocatalytic antibacteria materials mean that the antibacterial materials using photocatalytic properties of materials. Such as titanium dioxide, zinc oxide and other inorganic photocatalytic materials, the photo generated electrons(or holes) under the light irradiation are irrgrated to the cell nucleus, and made the cell to be oxidized(or restore) decomposition, therefore the bacterial were killed.In this paper,Bi2WO6-based composite photocatalysts were prepared and used in the photocatalytic antibacterial process. The prepared photocatalysts were characterized by X-ray diffraction(XRD),scanning electronic(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),and UV-vis diffuse reflectance spectra(DRS). The photocatalytic antibacterial experiments were carried out against the Gram-negative bacteria P. Aeruginosa and E. coli and the Gram-positive bacteria S. Aureus to evaluate the antibacterial performance of the prepared photocatalysts.First, bismuth nitrate(Bi(NO3)3·5H2O) and sodium tungstate(Na2WO4·2H2O)were used as raw materials, Bi2WO6 photocatalysts showed good visible light photocatalytic properties were successfully prepared by hydrothermal method.Ag3PO4 sensitized Bi2WO6 photocatalysts with different Ag3PO4 content were successfully synthesized by a facile deposition method at room temperature. By mixing the material with the bacterial suspension under visible light irradiation time,the use of statistics to characterize the material colonies photocatalytic antibacterial activity under visible light irradiation. It was also found that the Ag3PO4 ratio in the Bi2WO6/Ag3PO4 composites played an important role in the corresponding photocatalytic antibacterial properties, The optimized ratio was found to be 50%.Almost all(99.99%) of Escherichia Coli(E. coli) could be killed within 30 min in the presence of 50%Bi2WO6/Ag3PO4 under visible light irradiation. What is more,these materials did not exhibit significant loss of photocatalytic activity after the recycling experiments, indicating the stability and longer reusability.Then a novel Bi2WO6/BiOI heterojunction photocatalyst was prepared based on a chemical etching method. The as-prepared Bi2WO6/BiOI photocatalyst wascomposed of Bi2WO6 and BiOI. Experimental results indicated that the molar percentage of Bi2WO6 to BiOI leaded to different morphologies and photocatalytic activities of Bi2WO6/BiOI composites. 30%Bi2WO6/BiOI exhibited an improved photocatalytic performance under visible light irradiation compared to pure Bi2WO6,pure Bi OI, and other Bi2WO6/BiOI photocatalysts. Almost all(99.99%) of Pseudomonas Aeruginosa(P. Aeruginosa), Escherichia Coli(E. coli) and Staphylococcus Aureus(S. aureus) could be killed within 60 min in the presence of30%Bi2WO6/BiOI. In addition, after six circulating photocatalytic antibacterial experiments, 30%Bi2WO6/BiOI exhibited no significant loss of photocatalytic performance, verifying its stability and reusability. Moreover, a possible photocatalytic mechanism was proposed based on active species trapping experiments, demonstrating that the superoxide radicals(?O2-) and the holes(h+) were the main reactive species in this system. The obviously enhanced photocatalytic activity of the 30%Bi2WO6/BiOI heterojunction photocatalyst could be mainly attributed to the formation of the p-n heterojunction, accelerating the separation of photogenerated charge carriers.