Synthesis Of Bismuth Based Photocatalyst And Photocatalytic Degradation Performance

Nowadays,photocatalytic technology using sunlight to degrade and remove antibiotic organic pollutants has become a new and effective treatment method.The key to this technology is to select suitable photocatalytic materials,and bismuth-based semiconductor materials have been favored by many researchers because of their excellent degradation performance in energy band structure and band gap.In this paper,bismuth-based semiconductor materials are used as the research object,and two typical antibiotics,sulfadiazine（SDZ）and enrofloxacin（ENR）,are used to simulate pollutants to evaluate the photocatalytic degradation performance of the catalysts.The contents and results of the research are as follows:（1）The bismuth-rich bismuth bromideoxide(Bi₂₄O₃₁Br₁₀)was successfully prepared by the mixed solvothermal method.The results of photocatalytic degradation of SDZ showed that the optimal solvothermal temperature,solvothermal pH,catalyst dosage,initial pH of SDZ,and initial concentration of SDZ were 120℃,10,50 mg,3,and 5mg/L,respectively.The best degradation efficiency in 180 min can reach 96.2%.Cyclic degradation experiments proved that Bi₂₄O₃₁Br₁₀ has good stability.Free radical capture experiments found that the order of the effect of active species on photocatalytic degradation was·O₂^->h⁺>·OH.（2）BiOBr/β-Bi₂O₃ composite photocatalyst was synthesized by the solvothermal method.After the photocatalytic performance test,it was found that the catalyst synthesized at 140℃has the best photocatalytic degradation ability for SDZ and ENR.After 2 h of irradiation,the degradation efficiency is 95.3%and 98.9%,respectively,and the catalyst has good reusability.The strong acid solution is not conducive to the photocatalytic degradation reaction,and the pH value of the initial ENR has a significant impact on the dark reaction adsorption process of the photocatalytic degradation of ENR.Besides,·O₂^-contributes the most to the degradation reaction.（3）BiOBr/BiOCl composite photocatalyst was synthesized by microwave method.The experimental results showed that the catalyst prepared under the conditions of 1.5 g PVP and 40 m L water has the highest degradation efficiency for SDZ,and the degradation efficiency of 2 h is 93.9%;the catalyst synthesized under the conditions of 1.5 g PVP,30m L water and 10 m L ethylene glycol has the highest degradation efficiency for ENR,the degradation efficiency of 2 h is 98.1%,and the composite material has good stability.Strong acid and strong alkaline solutions are not conducive to the photocatalytic degradation of SDZ and ENR,respectively,and the pH value of the initial ENR has a greater impact on the adsorption stage of the dark reaction.Free radical capture experiments revealed that·O₂^-has the greatest effect on the degradation reactions of SDZ and ENR.（4）The BiOBr/Bi_3.84W_0.16O_6.24 composite photocatalyst was synthesized by microwave method.The results of the experiment found that the pure BiOBr is corresponding to the absence of ammonia,and the amount of Bi_3.84W_0.16O_6.24 increases gradually with the addition of ammonia.The results show that the composite has better photocatalytic activity than a single BiOBr.Among them,BiOBr/Bi_3.84W_0.16O_6.24（pH=7）has the highest photocatalytic activity,and the degradation efficiency can reach 91%in 2h.Repeated use experiments prove that the composite material has good photocatalytic stability.Also,it was found that strong acidic and strong alkaline solutions were not conducive to the degradation activity of SDZ.The free radical capture experiments indicated that the order of the active species to the degradation reaction was·O₂^->h⁺>·OH.