Preparation Of Bismuth-based Semiconductor Composite Catalysis And Its Visible Light Degradation Of Medical Antibiotics

The abuse of antibiotics in human beings and animals has made antibiotics a dangerous pollutant in environment,especially in water pollution.The development and application of new photocatalyst materials have become a hot spot of urgent concern.Bismuth-based semiconductor photocatalysts have attracted extensive attention because of their good response to visible light and green repeatability in natural environment.However,the application of bismuth based semiconductor photocatalysts in photocatalysis is severely restricted due to the rapid recombination of photogenerated electron hole pairs.In order to solve the above problems,bismuth-based semiconductor composite photocatalyst was prepared in this paper to obtain photocatalyst with high photocatalytic activity.The structure,composition and optical properties of bismuth-based semiconductor composite photocatalysis were characterized and analyzed by XPS,SEM,TEM,XPS,FT-IR and UV-VIS DRS.respectively.The photocatalytic performance of bismuth-based semiconductor photocatalyst was evaluated.Finally,the photocatalytic mechanism of the composites was studied in detail.The main contents of this thesis is mainly divided into the following three parts.1.BiVO4-C composite photocatalyst was synthesized by doping hollow carbon spheres to BiVO4 utilizing chemical precipitation method and hydrothermal mean.In the degradation experiments of rhodamine B（RhB）and tetracycline（TC）under simulated sunlight,the BiVO4-C composite photocatalyst with a molar doping content of 1.5%carbon spheres showed the highest photocatalytic activity.Uv-vis DRS spectroscopy,electrochemical impedance and photocurrent experiments showed that the loading of carbon spheres significantly enhanced the absorption of sunlight by BiVO4.Meanwhile,the high electric storage and high surface area of hollow carbon spheres were conducive to the transfer of photogenerated electrons of BiVO4,which improved the photocatalytic performance.2.A novel organic-inorganic composite photocatalyst（Self-assembled perylene diimide/bismuth vanadate）PDIsm/BiVO4 was constructed by hybridizing method and simple water bath heating method.A series of photocatalysts were prepared to degrade levofloxacin hydrochloride under visible light irradiation.The results showed that the photocatalytic activity of PDIsm/BiVO4 composite was superior to that of pure PDIsm and BiVO4.In addition,the disinfecting ability of PDIsm/BiVO4 was evaluated by the sterilization of Staphylococcus aureus under visible light.The results showed that PDIsm/BiVO4 had better disinfecting ability than BiVO4.The enhanced photocatalytic activity was mainly attributed to the construction of Z-type heterojunction structure,which enhanced the absorption of visible light and promoted the separation of photogenerated electron hole pairs.According to the results of electron spin resonance and active species capture experiments,it was confirmed that h+and ·O2-were the main active substance to enhance its photocatalytic and disinfecting abilities of PDIsm/BiVO4,and a general Z-scheme mechanism was put forward.3.In view of the energy band structure between PDIsm and Bi2O2CO3,Bi2O2CO3 was synthesized by hydrothermal method using formamide and PDIsm/Bi2O2CO3 composite photocatalyst was synthesized under water bath heating.The morphology,crystal lattice and elemental composition of the material were measured by SEM,HRTEM and XPS.In addition,the photocatalytic degradation experiments of the synthesized photocatalyst were carried out under visible light irradiation to investigate the degradation performance of levofloxacin hydrochloride.The results showed that PDIsm/Bi2O2CO3 composite photocatalyst had good photocatalytic performance,which can be attributed to the Type Ⅰ heteroj unction structure formed by PDIsm and Bi2O2CO3,improving the separation efficiency of photogenerated electron-hole pair.Moreover,the possible degradation path was speculated by analyzing the structure of intermediate fragments in the degradation process.Based on the experimental results of electron spin resonance and active species capture,the mechanism of Type Ⅰheterojunction photocatalysis was proposed.