Fabrication Of Photocatalysts For Enhanced Visible-light Responsivity And Performance In Photocatalytic Degradation Of Tetracycline

Tetracycline antibiotics are widely produced and used throughout the world as the second largest antibiotic.As a result of its abuse,it has caused serious pollution to the water environment around the world.At present,its treatment methods mainly include biological methods,physical methods,and common chemical methods.The above methods have many disadvantages.Based on the shortcomings of the above methods,photocatalytic technology has gradually become the focus of researchers and photocatalytic technology is in the treatment of sewage.There are many advantages,but the spectral response range is narrow and the low quantum efficiency limits its application.Based on the factors affecting the photocatalytic performance of semiconductor materials,this paper studies the modification of wide band gap materials from semiconductor compounding,morphology control and precious metal deposition.The photocatalytic efficiency of tetracycline（TC）was evaluated under visible light and the photocatalytic degradation mechanism was discussed.The research contents are as follows:（1）Based on semiconductor complex and morphology control.CuO/ZnO composites with different proportions and different morphologies were obtained by calcining different amounts of Cu²⁺with zeolite imidazole ester skeleton（ZIF-8）as precursor.The results also show that the addition of CuO increases the pore volume and surface area of ZnO,but excess CuO leads to the opposite result.The prepared hollow CuO/ZnO(n _Cu/Zn=0.1)photocatalyst has a degradation rate（DR）of about88%for tetracycline after 60 minutes under visible light（λ>420nm）,and its DR is significantly better than that of structurally completely collapsed CuO/ZnO(n _Cu/Zn=0.4),pure ZnO and CuO.（2）Based on semiconductor surface precious metal deposition.The Ag/g-C₃N₄photocatalytic material was constructed by photodeposition.The characterization results show that the Ag/g-C₃N₄ photocatalytic material is successfully prepared without other impurities,and can effectively improve the response range of visible light and promote the separation of photogenerated electron-holes.The photocatalytic degradation study showed that the photocatalytic DR of TC was 86%after 60 min of illumination.It still gives good photocatalytic activity after 5 repetitions.（3）Based on semiconductor complex and precious metal deposition modification methods.A petal-like Ag/AgCl/ZnO composite material was constructed by coprecipitation and photodeposition.The Ag/AgCl/ZnO composites have higher visible light response range and better photogenerated electron-hole separation effect.Among different materials,Ag/AgCl/ZnO exhibits a good photocatalytic effect.And in the Ag/AgCl/ZnO materials with different Ag/Zn ratios,ZAA-10（Ag/Zn=1:10）showed the best degradation effect（the degradation rate was 84%after 20 min under visible light）.In addition,the stability of ternary composite system,the structural destruction of TC,the catalyst and solution’s changes in the photocatalytic process(such as Zn²⁺concentration,p H value and catalyst composition before and after the reaction)were also investigated.