Preparation Of Bi₄O₅Br₂ Composite Catalysts And Their Visible Light Catalytic Degradation Performance Of Ciprofloxacin

In recent years,the problem of environmental pollution caused by antibiotics has attracted more and more attention.Compared with traditional wastewater treatment technology,semiconductor photocatalytic technology has the advantages of mild reaction conditions,high stability and low secondary pollution.It is a promising way to alleviate environmental problems.In this paper,two kinds of composite catalysts,including rGO/BiOBr/Bi₄O₅Br₂ and ZnO/Bi₄O₅Br₂,were prepared by one-step solvothermal/hydrothermal method.The synthesis conditions of the catalysts and the process conditions in the degradation process were investigated for the photodegradation of ciprofloxacin.This article focuses on the following aspects:?1?The rGO/BiOBr/Bi₄O₅Br₂ composites were prepared by one-step solvothermal method.The crystal forms,morphologies,optical properties and other properties of rGO/BiOBr/Bi₄O₅Br₂ composite catalysts were investigated by XRD,SEM,PL,UV-vis DRS and other characterization tests.The results showed that the incorporation of rGO can broaden the visible light response range of the sample,inhibit the recombination of electron-hole pairs,and the free radical trap test showed that the holes and superoxide groups are the main active species in the photodegradation process.The photo-generated carrier transfer mechanism in the semiconductor during photodegradation of ciprofloxacin was inferred.In addition,the effects of the amount of rGO content,the pH,temperature and time of the solvothermal reaction on photocatalysis were investigated.When the illumination time is 90 min,the photocatalytic activity of ciprofloxacin can reach 97.4%under the synthesis conditions are 1 wt%rGO,pH at 7,hydrothermal temperature of 180°C,hydrothermal time of720 min.?2?The ZnO/Bi₄O₅Br₂ composites were synthesized by one-step hydrothermal method.The components and surface morphologies of the composite catalysts were investigated by XRD and SEM.The effects of the addition amounts of NaOH,molar ratio of bismuth nitrate and zinc nitrate,temperature and time of the hydrothermal reaction on photocatalysis were investigated.The experimental results show that the photodegradation of ciprofloxacin can reach 93.3%when the ZnO/Bi₄O₅Br₂composites synthesized with NaOH of 1.3 mL,molar ratio of bismuth nitrate and zinc nitrate is 2:1,hydrothermal temperature of 120°C,and hydrothermal time of 540 min under 120 min illumination.The technological conditions of photodegradation of ciprofloxacin by ZnO/Bi₄O₅Br₂ composites were investigated,including catalyst dosage,ciprofloxacin concentration and degradation temperature.The experimental results show that the photocatalytic activity of ZnO/Bi₄O₅Br₂ composites is optimal when the degradation conditions are catalyst of 0.10 g,ciprofloxacin of 12 mg/L and degradation temperature of 20°C.