Preparation Of Bi-based Photocatalyst And Study On Its Degradation Performance For Tetracycline Hydrochloride

The problem of energy shortage and environmental pollution has always been the focus attention of society and people.The rapid development of global industry has led to the extensive consumption of fossil fuels.The harmful substances produced by industrial production,the burning of fossil fuels and the massive use of chemical substances are discharged into the air,water and soil,seriously polluting the environment and endangering people's health.Tetracycline hydrochloride?TCH?is a common antibiotic,when that remains in the environment,it can induce the production of pathogens resistant to antimicrobial drugs.Moreover,TCH is difficult to be eliminated.Some traditional methods of treating TCH,such as physical adsorption and biodegradation,that is too cumbersome,and have high processing costs and poor antibacterial properties.Photocatalytic technology is regarded as a new type of degradable TCH due to its advantages of green,pollution-free,relatively simple operation and equipment.BiOX?X=F,Cl,Br,I?is a type of semiconductor photocatalyst with a special layered structure,which has large specific surface area and built-in electric field,so it is widely used in photocatalytic reactions.However,when BiOX is used alone as a catalyst,the electron-hole pair separation is weak and the carrier transport is slow.In order to improve the charge transfer rate of the material and reduce the recombination of photogenerated electrons and holes,this paper takes BiOX as the research object,mainly through a series of modification of BiOX by using two-dimensional materials that with large specific surface area and good conductivity to study its degradation of pollutants.Because the two-dimensional co-catalyst can be combined with layered BiOX to increase the specific surface of the composite catalyst,promote the transport of photogenerated electrons,and improve the separation efficiency of photogenerated carriers.The main research contents and results are as follows:?1?BiOCl/x%?–Bi₂O₃ composite catalysts were successfully synthesized by a simple precipitation method.The photocatalytic degradation of environmental pollutants was studied using TCH as the degradation target.The experimental results show that the degradation rate of BiOCl/x%?–Bi₂O₃ to TCH can reach 78%under simulated sunlight,,showing excellent photocatalytic degradation performance.Cycle experiments show that the BiOCl/x%?–Bi₂O₃ composite catalyst has excellent cycle stability.?2?In order to improve the utilization efficiency of sunlight,BiOCl is doped and modified by introducing I element in the above materials without changing the characteristics of its two-dimensional structure,BiOCl_0.9I_0.1/x%?-Bi₂O₃ composite catalyst that can respond to visible light was successfully prepared.The samples were analyzed and characterized by XRD,SEM,TEM,UV-Vis DRS and other means,and the photocatalytic activity of the samples was evaluated by the degradation of TCH in water under simulated sunlight.Compared with pure BiOCl_0.9I_0.1.1 and pure?-Bi₂O₃,the composite catalyst BiOCl_0.9I_0.1/x%?-Bi₂O₃ shows more excellent photocatalytic activity.Among them,BiOCl_0.9I_0.1/15%?-Bi₂O₃ can degrade tetracycline hydrochloride in water up to 82.4%.At the same time,cycling experiments show that BiOCl_0.9I_0.1/x%?-Bi₂O₃composite catalyst has excellent cycle stability.?3?Use the prepared BiOCl_0.9I_0.1.1 that can respond to visible light to combine with two-dimensional SnS₂,formed BiOCl_0.9I_0.1/x%SnS₂ composite catalyst.TEM,XRD,and XPS spectra have proved the successful preparation of BiOCl_0.9I_0.1/x%SnS₂composite catalysts and the?110?and?100?crystal planes of BiOCl_0.9I_0.1.1 and SnS₂ can also be clearly observed through the lattice fringes in the HRTEM image.The photocatalytic degradation of TCH in water was selected as the evaluation basis,and the photocatalytic activity of BiOCl_0.9I_0.1/x%SnS₂ composite was investigated under visible light.Compared with pure BiOCl_0.9I_0.1.1 and pure SnS₂,BiOCl_0.9I_0.1/7%SnS₂ can degrade TCH in water up to 76%,the degradation rate is significantly increased,and the results of cycling experiments can also show that BiOCl_0.9I_0.1/x%SnS₂ composite catalyst has excellent cycle stability.