Preparation Of Bi₂WO₆-based Photocatalyst And Research On Degradation Of Antibiotics

Over the past few decades,antibiotics have been widely known and used by humans,especially in water,sediments and soil,and have increasingly accumulated into a new type of environmental pollutants.Therefore,many environmental workers conduct research on the treatment of antibiotic pollution.In recent years,a new type of treatment method,photocatalytic oxidation technology,has been developed.In the presence of a photocatalyst,it can use natural sunlight to achieve a perfect removal of antibiotics.It has the characteristics of no toxicity,no harm,no secondary pollution and high efficiency and low cost,so it is favored by the majority of researchers.Among them,bismuth tungstate（Bi₂WO₆）-based photocatalysts show excellent photocatalytic activity with improved charge transfer capability.In this paper,three methods of I-doping,Er³⁺doping and Fe₃O₄-loaded Bi₂WO₆ were used to modify Bi₂WO₆ nanomaterials to develop a visible light-responsive Bi₂WO₆-based photocatalyst.The effect of single-factor conditions on photocatalytic degradation was studied and the light was discussed.The main mechanism in the process of catalytic degradation of tetracycline wastewater provides scientific and technological methods and experience for the development of highly efficient and deeply effective new visible light-responsive materials that degrade organic pollutants in environmental water bodies and their application in practical fields.（1）A series of new I-doped Bi₂WO₆ BiI/BWO composite photocatalytic materials were successfully synthesized by a simple and efficient one-step hydrothermal method.The catalysts were characterized by XRD,SEM,UV-Vis DRS,XPS,BET and other characterization methods,and it was found that the introduction of I can effectively improve the photocatalytic activity of the composite.The results show that the photocatalytic degradation performance of BiI/BWO composite material under the visible light（λ>420 nm）of 350 W xenon lamp on tetracycline in water is higher than that of pure Bi₂WO₆.Among them,0.8I-BiI/BWO showed the best photocatalytic performance,capable of degrading about90%of tetracycline in 80 minutes of light.In addition,·OH and·O₂^-were found to be important active substances in the photodegradation process,and the photodegradation activity of the material for tetracycline did not decrease significantly after three cycles.（2）A series of Er³⁺-Bi₂WO₆ photocatalysts were prepared by a simple and efficient one-step hydrothermal method.XRD,SEM,TEM,PL,BET and other methods were used to characterize the different amounts of Er³⁺doped Bi₂WO₆ catalysts.The results show that the16%Er³⁺-Bi₂WO₆ composite has a narrower band gap and a larger specific surface area than pure Bi₂WO₆,which can effectively improve the photocatalytic activity of the composite.Under the visible light of a 350 W xenon lamp（λ>420 nm）,the degradation rate of tetracycline by the 16%Er³⁺-Bi₂WO₆ composite catalyst in 60 minutes of illumination was as high as 99%.In addition,e^-is the main active substance in the photodegradation process,and the results of the cyclic stability experiment show that the 16%Er³⁺-Bi₂WO₆ composite material has good photocatalytic stability.（3）The two-step solvothermal method was used to successfully synthesize Fe₃O₄/Bi₂WO₆ three-dimensional flower-like composite materials.XRD characterization analysis found that all prepared samples were highly crystalline.BET characterization found that 5.4%Fe₃O₄/Bi₂WO₆ composite material had a high specific surface area.It can improve its photocatalytic performance in the treatment of tetracycline aqueous solution.Using the prepared Fe₃O₄/Bi₂WO₆ catalyst under the irradiation of visible light（λ>420 nm）,the photocatalytic performance of tetracycline was studied.It was found that when the loading of Fe₃O₄ was 5.4%,the dosage was 0.6 g/L,the pH of the hydrothermal reaction precursor was3.0,and under the irradiation of 500 W xenon lamp,the Fe₃O₄/Bi₂WO₆ composite material exhibited the strongest degradability of the tetracycline solution in the same single-factor influence experiment.