Synthesis Of Cadmium Ferrite Nanocomposites And Their Application In Antibiotic Degradation And Detection

In the past few decades,the discovery and application of antibiotics have helped people treat bacterial infections.However,the widespread use of antibiotics makes it easy to spread to the water environment through domestic and industrial wastewater,resulting in serious environmental pollution.Therefore,it is necessary to solve the environmental crisis affecting human health.Semiconductor photocatalysis has received considerable attention because of its environmentally friendly properties,in order to solve people’s concerns about environmental pollution and solar energy crisis.In the process of photocatalysis,photogenerated electrons and hole pairs are separated by light excitation,and then migrate to the surface reaction site of the whole body to degrade pollution.Previous studies have proposed some effective strategies to promote the separation of charge carriers and improve the degradation efficiency,such as element doping,defect engineering and heterojunction formation.In addition,the trace detection of antibiotics is also important,people need sensitive and selective methods to detect antibiotics.At present,a variety of analytical methods for the detection of antibiotics have been established.Among them,electrochemical method has a broad application prospect in the analysis and detection of antibiotics because of its high sensitivity,high accuracy and trace detection.In this paper,two different kinds of cadmium ferrite nanocomposites,molybdenum disulfide/cadmium ferrite(MoS2/CdFe2O4)and strontium titanate/cadmium ferrite(SrTiO3/CdFe2O4)were synthesized.The morphology,size and element composition of the composites were studied by high power transmission electron microscopy,X-ray photoelectron spectroscopy,fourier transform infrared spectroscopy and other characterization techniques.Then through the optimization and adjustment of the material ratio and experimental conditions,the optimal value of the properties of the composites was found.It is used for the degradation and detection of antibiotics and its performance is investigated.The main results are as follows:(1)MoS2/CdFe2O4 composites were prepared by two-step hydrothermal synthesis,and a photocatalyst was constructed.The photocatalytic degradation efficiency of tetracycline(TC)by 60%MoS2/CdFe2O4 is as high as 87.0%,which is better than monomer MoS2,CdFe2O4 and composites with different mass ratios.Through the band gap,conduction band and valence band position obtained by UV-Vis DRS spectrum and Mott-Schottky spectrum,the Z-type heterostructure is proposed.Hydroxyl radical(·OH)and hole(h+)are the main active species for photocatalytic degradation of TC by 60%MoS2/CdFe2O4.(2)SrTiO3/CdFe2O4 composites were prepared by hydrothermal method.The construction of type I heterojunction expands the light response of SrTiO3/CdFe2O4 complex to the visible region and improves the photodegradation performance.Under visible light,the photodegradation efficiency of ciprofloxacin(CIP)by 60%SrTiO3/CdFe2O4 is as high as 85.5%in 120 minutes,which is much higher than that of its monomer material.The recombination of SrTiO3 and CdFe2O4 improves the rapid recombination of electron-hole pairs and improves the efficiency of electron separation.In the process of photodegradation of CIP,the main role is ·O2-,followed by h+and OH.(3)On the basis of synthesis in(2),SrTiO3/CdFe2O4 composites were used to modify the electrode to detect the electrochemical sensing properties of norfloxacin,and the ratio of the material,the amount of drip coating,the pH value and scanning rate of the solution were optimized to determine the best experimental conditions.Under the above conditions,the electrochemical detection of norfloxacin solution was carried out by cyclic voltammetry.There is a good linear relationship between the concentration of norfloxacin and the peak current in the range of 1×10-8 M-1×10-4 M,and the detection limit LOD(3σ/S)is 0.064μM.