Performance And Mechanism Of Bismuth-based Inorganic Imprinted Photocatalyst For Selective Photodegradation Of Ciprofloxacin Residues

Ciprofloxacin（CIP）is a commonly used antibiotic sterilization drug,which is widely used in clinical research and animal husbandry.However,excessive use of CIP causes CIP residues in the water environment,which has a very serious impact on the ecological environment and human health.Water environment is complex,which contains not only residual CIP,but also some non-toxic harmless and recyclable substances.The traditional treatment technology cannot selectively adsorb and remove such low concentration,difficult to remove and highly toxic substances as CIP,which greatly reduces the treatment efficiency.The imprinted photocatalytic technology is not only green and environmentally friendly,without secondary pollution,but also can synthesize imprinted pores to specifically adsorb CIP,which effectively improves the efficiency of water treatment.Therefore,imprinted photocatalytic technology was selected to deal with CIP residue.However,the existence of organic imprinted layer on the surface of the traditional imprinted photocatalyst will affect the photocatalytic activity,and may also react with the photocatalyst,resulting in poor stability of the photocatalyst.The preparation process of inorganic imprinted photocatalyst is to directly combine the template molecules with the raw materials for the preparation of inorganic photocatalyst.The preparation process is relatively simple,and the organic imprinted layer at the coating active site will not be produced,nor will the redox reaction occur with the photocatalyst,so as to improve the stability of inorganic imprinted photocatalyst.Therefore,inorganic imprinting photocatalytic technology was introduced to achieve the selective removal of CIP residues in water environment under light.In addition,due to the good stability and light response ability of bismuth-based materials,it can better remove organic pollutants and is a good inorganic photocatalyst.Therefore,this study used bismuth-based inorganic photocatalyst to selectively degrade CIP residues in water.In summary,CIP was used as the template molecule in this paper to introduce the inorganic imprinting photocatalytic technology in the synthesis process of bismuth-based inorganic photocatalyst to achieve the purpose of selective photodegradation of CIP residual pollutants by bismuth-based inorganic imprinting photocatalyst.The main research contents are as follows:（1）Flake Bi₄Ti₃O₁₂ photocatalyst（F-BTO）was synthesized by a simple hydrothermal reaction using CIP as the template molecule,and it was modified by inorganic imprinting.Finally,FII-BTO with specific imprinted pores was synthesized.In order to achieve the best photocatalytic performance,the lamellar structure of inorganic imprinted Bi₄Ti₃O₁₂photocatalyst（FII-BTO）was controlled by adjusting the proportion of TB and OA during the hydrothermal reaction.The structure,composition,morphology,photoelectric chemistry and other properties of FII-BTO were investigated by XRD,XPS,SEM,TEM,photocurrent and impedance.Through photocatalytic activity and selectivity inspected photocatalytic activity and selectivity of the materials,and the mechanism of photocatalytic degradation was elaborated.It shown that the photodegradation rate of CIP by FII-BTO is 55.76%,which is better than that of F-BTO（41.48%）.The presence of imprinted holes can specifically adsorb CIP residues.The k selectivity of FII-BTO to F-BTO is 1.81,which has excellent selective photocatalytic degradation ability.（2）Flower-like Bi₄Ti₃O₁₂ photocatalyst（FG-BTO）was synthesized by sol-gel method with CIP as template molecule,and it was modified by inorganic imprinting.Finally,the flower-like inorganic imprinted Bi₄Ti₃O₁₂ photocatalyst（FGII-BTO）with imprinted pore-specific adsorption was synthesized.The optimal photocatalytic performance of FGII-BTO was achieved by adjusting the addition position and dosage of template molecule CIP in the sol-gel process.The structure,morphology and photoelectric response of FGII-BTO were investigated by XRD,XPS,SEM,TEM and electricity impedance.Through photocatalytic activity and selectivity inspected photocatalytic activity and selectivity of the materials,and the mechanism of photocatalytic degradation was elaborated.It shown that the photodegradation rate of CIP by FGII-BTO was 64.2%,25.2%higher than that by FG-BTO（39.0%）.FGII-BTO showed good selective photocatalytic degradation performance.（3）BiFeO₃ photocatalyst（BFO）was synthesized by sol-gel method with CIP as template molecule,and it was modified by inorganic imprinting to obtain imprinted pores with specific adsorption capacity.Finally,inorganic imprinted Bi Fe O₃photocatalyst（II-BFO）that can specifically adsorb CIP residue was prepared.The structure,morphology,magnetic separation ability and photoelectric properties of II-BFO were investigated and tested by XRD,XPS,SEM,TEM,VSM and photocurrent.Through photocatalytic activity and selectivity inspected photocatalytic activity and selectivity of the materials,and the mechanism of photocatalytic degradation was elaborated.It shown that the photocatalytic degradation rate of II-BFO（62.81%）for CIP under visible light was 2.52 times that of BFO（24.93%）,and the k-selectivity of II-BFO for BFO was 1.79.II-BFO showed good selective photocatalytic degradation performance.