Preparation Of Bismuth Oxychloride (Bi₁₂O₁₇Cl₂) Ccomposite Photocatalytic Material And Its Removal Performance For Organic Pollutants In Water

To meet the requirements of resource utilization,industrial development,regional coordination and human everyday future society,the development rate of water resources is increasing sharply.In recent years,the organic pollution of water is becoming increasingly serious.The pollution（such as antibiotics,environmental hormones,etc.）causes red tide,a large amount of ocean species death and even extinction,which seriously affect human health and social security.Photocatalytic technology has important application potential for treating organic pollution in the marine environment.The pivotal of this technology rests with the exploitation of excellent photocatalytic materials.The widely studied photocatalysts in the early stage suffer from some problems,including wide energy band-gap,short lifetime of electron and hole,etc.Given this,Bi₁₂O₁₇Cl₂ materials were successfully prepared by solvothermal method in this study.Two series of ternary Bi₁₂O₁₇Cl₂ heterojunction photocatalytic materials(Ag/Ag₆Si₂O₇/Bi₁₂O₁₇Cl₂ and Ag/Ag₂O/Bi₁₂O₁₇Cl₂)were further constructed by an in-situ deposition route,followed by the photo-reduction treatment.The preliminary research results are as follows:（1）A ternary Ag/Ag₆Si₂O₇/Bi₁₂O₁₇Cl₂ heterojunction was successfully constructed based on hydrothermal-in-situ deposition-light reduction method for photocatalytic degradation of contaminated antibiotic wastewater3D flower spherical Bi₁₂O₁₇Cl₂ was firstly synthesized by hydrothermal synthesis and high-temperature calcination.Then Ag/Ag₆Si₂O₇/Bi₁₂O₁₇Cl₂ heterostructures were synthesized by in-situ deposition and photo-reduction method.A series of methods including the X-ray diffraction analysis（XRD）,X-ray photoelectron spectroscopy analysis（XPS）,UV-vis diffuse reflection（UV-vis DRS）,scanning electron microscope（SEM）,transmission electron microscopy（TEM）,specific surface area analysis（BET）were used to represent the composition of the material,structure form,specific surface area.The results indicate that the heterojunction structure materials have been successfully synthesized and the structure of 3D flower spherical Bi₁₂O₁₇Cl₂ has not been destroyed by the introduction of Ag/Ag₆Si₂O₇.The separation of photogenerated electron holes was studied by photocurrent and electrochemistry.The photocatalytic degradation efficiency of AASi O/Bi OCl-5%heterojunction up to 85%during the experiment of degradation of TC and LEV under visible light.In the degradation of TC solution,the apparent rate constants of AASi O/Bi OCl-5%were 16.125 times and 2.93 times of pure Ag₆Si₂O₇ and pure Bi₁₂O₁₇Cl₂,respectively.In the degradation of LEV solution,the apparent rate constants of AASi O/Bi OCl-5%were 5.65 times and 4.97 times of pure Ag₆Si₂O₇ pure Bi₁₂O₁₇Cl₂,respectively.The results of recycling experiments and characterization of the recovered materials show that the composite has not only strong visible light catalytic activity,but also good structural stability and recycling property.The capture experiments of active substances showed that the main active substances of Ag/Ag₆Si₂O₇/Bi₁₂O₁₇Cl₂heterojunction in the degradation of organic pollutants were superoxide radicals and holes.According to the research results,the photocatalytic mechanism of Ag/Ag₆Si₂O₇/Bi₁₂O₁₇Cl₂ heterojunction in the degradation of antibiotics was proposed.（2）A ternary Ag/Ag₂O/Bi₁₂O₁₇Cl₂ heterojunction was successfully constructed based on hydrothermal-in-situ deposition-light reduction method for photocatalytic degradation of contaminated antibiotic wastewaterIn order to improve the efficiency of holes separation and broaden the range of visible light response,we attached Ag/Ag₂O to Bi₁₂O₁₇Cl₂.The crystal structure,chemical composition,morphology,optical,electrical properties and stability of Ag/Ag₂O/Bi₁₂O₁₇Cl₂heterojunction were analyzed by systematic characterization method.It is concluded that Ag/Ag₂O uniformly adheres to the surface of Bi₁₂O₁₇Cl₂.And the ternary heterojunction is successfully constructed.The addition of Ag/Ag₂O not only does not change the morphology and structure of Bi₁₂O₁₇Cl₂,but also improves the separation efficiency of photogenerated electron holes.The experimental results of degradation of antibiotic aqueous solution by visible light show that the performance of the composite material is greatly improved.The degradation efficiency of AAO/Bi OCl-30%under visible light is close to 90%.The apparent rate constant of AAO/Bi OCl-30%in the degradation of TC solution is about 13 times of pure Ag₂O and about 3.2 times that of pure Bi₁₂O₁₇Cl₂.And about 2 times of pure Bi₁₂O₁₇Cl₂ in the degradation of LEV solution.The capture experiment showed that the main active substances in the degradation of organic pollutants were holes and superoxide radicals.Finally,the photocatalytic mechanism of Ag/Ag₂O/Bi₁₂O₁₇Cl₂ heterojunction in the degradation of antibiotics was proposed.In addition,the composite material is easy to recycle,has good stability and can be reused.