Preparation Of Bismuth Vanadate Based Semiconductor Composites And Their Performance For Tetracycline Removal

At present,because antibiotic resistance is threatening global health,the emergence of"super bacteria"has attracted great attention from all over the world.Residual antibiotics in the environment are the main cause of the crisis,and their efficient removal is urgently needed.Recently,adsorption and photocatalysis technologies have been widely used in various fields due to their advantages of simple operation,high efficiency and low cost.Bismuth vanadate has become one of the candidates for semiconductor materials with excellent performance and has broad prospects in the removal of residual TC because of its inherent narrow band gap,light response capability and chemical stability.However,its development is limited by the small specific surface area and low photogenerated electron-hole separation efficiency.Therefore,this paper takes Bi VO₄ as the research object,and modifies it by constructing composites to improve the removal performance of residual tetracycline in water.The specific research contents are described as follows:(1)The introduction of W₁₈O₄₉ containing defect structure by solvothermal method increases the specific surface area of the Bi VO₄/W₁₈O₄₉ composite material and improves its adsorption performance for tetracycline.In the experiment of removing tetracycline,the BW-0.8 composite showed the best adsorption performance.The removal efficiency of TC could reach 80.9%within 40 minutes,which was about 12.64 and 1.67 times higher than that of pure Bi VO₄ and W₁₈O₄₉,respectively.In addition,it also showed excellent adsorption performance in the removal experiments of tetracycline and quinolone antibiotics,proving that the adsorbent has a wide range of applications.The results of adsorption kinetics and thermodynamics revealed that the adsorption reaction is a typical chemical adsorption process,which is a spontaneous endothermic reaction.(2)The Z-type heterojunction Bi VO₄/Bi₂S₃ photocatalyst was designed by the hydrothermal and ion exchange methods,and the PBB flexible photocatalytic film was further prepared by the casting method.The photocatalytic degradation performance of tetracycline was investigatived.The experimental results found that the BB-3 photocatalyst exhibited excellent photocatalytic degradation activity under different light sources.The degradation efficiency under visible light was 73.2%,which was about 2.44 and 3.30 times higher than that of pure Bi VO₄ and Bi₂S₃,respectively.The photocatalytic degradation efficiencies in the full spectrum and near-infrared regions were 79.7%and 64.3%,respectively.More importantly,the PBB flexible photocatalytic film also exhibits degradation efficiency similar to that of the solid powder photocatalyst,which improves the practicability of the material without affecting the photocatalytic degradation performance.Finally,combining the energy band structure and optical properties of semiconductors,the photocatalytic degradation pathway and mechanism of Z-type heterojunction Bi VO₄/Bi₂S₃photocatalyst for TC was proposed.