Preparation Of Bi Ox Catalyst For Photocatalytic Disinfection Of Escherichia Coli Under Visible Light Irradiation

Photocatalytic sterilization is considered to be a high potential microbial treatment technology because of the fact of its through sterilization, high efficiency and no secondary pollution. E. coli strains is an indication of water pollution, has the practical significance. BiOX(X = Br, I) photocatalyst due to its unique electronic structure and the energy band structure, showed in visible light catalytic properties superior to other semiconductor activity, and the existence of the heterojunction greatly improved its visible light catalytic properties. However this series of materials photocatalytic sterilization properties and the mechanism are still unclear. Therefore,this paper adopts the solvent thermal step synthesis, BiOBr preparation monomer,monomer BiOI and 50% BiOBr/BiOI heterojunction three kind of photocatalyst, and by using SEM, EDS, XRD, UV-vis, BET and HRTEM on synthesis methods such as the phase structure of the sample, band structure, specific surface area, the visible light catalytic performance of sterilization and its mechanism were studied.Using Bi(NO3) 3 · 5 H2 O, PVP(K30), KBr or KI, anhydrous ethanol as raw material, solvent hot method step in the preparation of hierarchical BiOBr, and BiOI microspheres structure light catalyst. SEM figure showed that the synthetic materials for the 3 d structure of hierarchical microspheres. EDS analysis wss consistent with the XRD results, all for a single material. UV-vis analysis, Eg of BiOBr forbidden band width is about 2.68 eV, BiOI forbidden band width is1.76 eV. Sterilization performance study showed that the material concentration was 0.5 mg/mL time catalytic best sterilization effect, 12 h after visible light irradiation, the inactivation rate of E.coli can reach 70% and 80%. Given higher initial microbial concentration was higher, would lead to worse sterilization effect. Escherichia coli TEM photo before and after visible light irradiation,the potassium ion leakage more and live/dead bacteria staining fluorescence micrographs showed that the bacterial cell membrane was damaged. Join different free radical scavenger, resultsshowed that the BiOBr and BiOI photocatalytic sterilization process of the cavity as the main active group.Using Bi(NO3) 3 · 5 H2 O, PVP(K30), KBr and KI, anhydrous ethanol as raw material,solvent hot method step in the preparation of 50% BiOBr/BiOI heterojunction composite photocatalyst. EDS and XRD results were in agreement with the analysis results, for the preparation of samples of two kinds of monomer of composite materials.UV- vis analysis, 50% of BiOBr/BiOI forbidden band width was about 1.90 eV. HRTEM results showed that the composite material has heterojunction.Sterilization performance study showed that the material concentration was 0.5 mg/mL time catalytic sterilization effect best, 12 h after visible light irradiation, E. coli inactivation rate could reach 90%. Microbial initial concentrationwas higher, the sterilization effect was poorer. Due to the heterojunction and good visible light absorption rate, sterilization effect was superior to single composite material. Join different free radical scavenger, the results showed that 50% of BiOBr/BiOI photocatalytic sterilization process cavity as the main active group.