Preparation Of BiOBr And WO₃/BiOBr And Study On The Visible Light Photocatalytic Degradation Properties Of Antibiotic

Antibiotics as a large class of drugs,is widely used in the medical industry,agriculture,animal husbandry,aquaculture and other fields.Due to the extensive application of antibiotics,there are different levels of antibiotics containing in the wastewater.With the traditional sewage treatment method can not effectively remove the antibiotics,the antibiotics can be frequently detected in the world's lakes,rivers and bays.Antibiotics in the water can lead to water environment tolerance of pathogens and a large number of drug-resistant genes,which will threaten the ecological balance and human health.So how to remove the antibiotics in the water has become an urgent problem to be solved.As a kind of advanced oxidation method,photocatalytic method can effectively degrade and remove antibiotics in water.It has the advantages of mild reaction condition,simple operation,reusable,economical,and difficult to cause secondary pollution.Compared with the traditional photocatalyst,visible light photocatalyst can respond to visible light,and can catalyze the degradation of pollutants with sunlight.In this paper,BiOBr and WO₃/BiOBr photocatalysts were synthesized by solvothermal method,and were characterized and analyzed.WO₃/BiOBr was used to degrade Tetracycline hydrochloride and WO₃/BiOBr was used to degrade Ciprofloxacin hydrochloride under visible light.The photocatalytic activity and degradation mechanism were studied.The main conclusions are as follows:1?The BiOBr photocatalyst was successfully synthesized by solvothermal method.The results showed that the solvent's type had a great effect on its morphology.When C3H8O2 was the solvent,the BiOBr's morphology tend to be microsphere.When the solvent was ethanol,the BiOBr sheets were synthesized.The specific surface area of BiOBr microspheres is 3.85 times of that of BiOBr sheets.Although the morphologies of BiOBr are changed,the crystal structures of BiOBr are basically the same.The band gap are almost 2.6 eV,there is no significant difference between these two kinds of BiOBr.2?The results shows that when BiOBr microsphere is the photocatalyst,The Tetracycline hydrochloride's degradation efficiency could reach 99.5% in 240 min,and only 25% Tetracycline hydrochloride can be removed when BiOBr sheets were uesed.BiOBr microspheres have higher photocatalytic activity than BiOBr sheets,which may be mainly due to the larger specific surface area of microspheres,and thus microspheres have more adsorption and reaction sites.3?The biodegradation of tetracycline hydrochloride by BiOBr microspheres was optimized by single factor experiment and response surface method.The optimal conditions were as follows: the dosage of BiOBr microspheres was 654.79 mg/L,the initial concentration of tetracycline was 10 mg/L,pH=7.And the removal rate of Tetracycline hydrochloride in water was about 94% under the optimized conditions for 120 min.4?WO₃/BiOBr composite photocatalyst was successfully prepared by solvothermal method.The results of the characterization analysis showed that the band gap of WO₃/BiOBr was about 2.71 eV and the BiOBr band gap was about 2.90 eV.Fluorescence spectroscopy analysis showed that WO₃/BiOBr photogenerated hole electron separation's ability was stronger than that of BiOBr or WO₃ alone.In the specific surface area test,it can be found that the specific surface area of WO₃/BiOBr composite photocatalyst is about 4 times higher than the specific surface area of WO₃.5?The degradation of Ciprofloxacin hydrochloride with WO₃/BiOBr,BiOBr or WO₃ in visible light showed that the removal efficiency of Ciprofloxacin hydrochloride could reach 83.1% within 120 min with the WO₃ /BiOBr composite photocatalyst,The removal efficiency of Ciprofloxacin hydrochloride were only 70% and 20%,when the BiOBr or WO₃ was used.The catalytic performance of the composite is better than that of the single photocatalyst.This is probably due to the band structure of the composite material and its large specific surface area.6?The system of degradation of Ciprofloxacin hydrochloride under visible light was optimized and studied by using the single factor experiments on WO₃/BiOBr composite photocatalyst.It was found that the removal efficiency of Ciprofloxacin hydrochloride was 96.62% in 120 min when the initial concentration was 15 mg/L,the dosage was 500 mg/L and the pH was 8.5.The photocatalytic efficiency was higher under alkaling conndition.7?It is found that the active radicals of BiOBr microspheres that play a major role in the degradation of Tetracycline hydrochloride are superoxide radicals?O2.-?,and the holes?h +?also play an improtent role according to the free radical capture experiments' result.The superoxide radical?O2.-?played an important role in the degradation of tetracycline hydrochloride with WO₃/BiOBr composite photocatalyst.