Mechanism Of NiFe-LDH/Ti₃C₂ For Heterogeneous Photo-Fenton Degradation Of Tetracycline In Water

In recent years,the problem of water pollution caused by antibiotics is getting worse.Because of its green,high-efficiency and wide application range,the Photo-Fenton has been widely used to degrade wastewater containing tetracycline.Layered double hydroxides（LDHs）,also known as hydrotalcite,is a widely used photo-Fenton catalytic material.LDH has many advantages,such as:large specific surface area,strong light absorption capacity,many surface-active sites.However,the high loading rate of photogenerated electrons and holes and low carrier mobility of LDH limit its photo-Fenton catalytic performance.By combining with materials with excellent electrical conductivity,it is expected to greatly improve the catalytic performance of LDH and broaden the application of LDH in the photo-Fenton field.In this study,titanium carbide（Ti₃C₂）with excellent conductivity was introduced into NiFe-LDH,and NiFe-LDH/Ti₃C₂ composite materials with different Ti₃C₂ addition levels were successfully prepared and used for photo-Fenton catalytic degradation of tetracycline（TC）.SEM and TEM characterizations show that the composite material prepared by hydrothermal method has better dispersibility,and Ti₃C₂ nanosheets are uniformly supported on the surface of NiFe-LDH.EDX characterization shows that the elements in the composite are evenly distributed.The XPS characterization proved that the composite materials are connected through the interaction of O-C=O and Ti-O bonds.At the same time,the structure of the functional groups on the surface of the composite materials is analyzed by FTIR.According to the BET characterization and analysis,the specific surface area（93.2556m²/g）of the NiFe-LDH/Ti₃C₂ composite prepared by the hydrothermal method has a certain degree of increase compared with the NiFe-LDH monomer（67.2542m²/g）.UV-vis DRS analysis shows that Ti₃C₂ can greatly increase the absorbance of the composite.PL characterization shows that NiFe-LDH/Ti₃C₂composites have better electron-hole separation efficiency than NiFe-LDH.In this experiment,the NiFe-LDH/Ti₃C₂-40 composite material has a good photo-Fenton degradation effect on TC,Under the experimental conditions that the concentration of TC is20mg/L,the concentration of H₂O₂ is 20m M,the catalyst loading is 0.2g/L,and the temperature is 25℃,NiFe-LDH can only degrade 54%of TC in 90 minutes,while the NiFe-LDH/Ti₃C₂-40 composite material has a TC removal efficiency of 94.7%.Free radical capture experiments prove that hydroxyl radicals and superoxide radicals are the most important active substances for efficient degradation of TC.Light and NiFe-LDH photo-excited electrons can accelerate the Fe³⁺/Fe²⁺redox cycle.Cyclic experiments prove that composite materials have good reusability.Inorganic ion interference experiments show that various inorganic ions(Cl^-,SO₄^2-,NO₃^-,HCO₃^-,PO₄^2-,Ca²⁺,Mg²⁺)have a certain effect on the degradation of TC in the catalytic system.At the same time,the catalytic performance of NiFe-LDH/Ti₃C₂composite material when applied to actual water body was also investigated.