Study On Preparation Of Modified Diatomite Loaded Nanometer Fe-Ni Bimetal And Removal Of Typical Antibiotics

The extensive use of antibiotics in the medical,agricultural,animal husbandry and breeding industries not only causes a lot of pollution to the ecological environment,harms the human body,animals and plants,but also increases the resistance of pathogenic microorganisms.Therefore,the removal of antibiotics has received widespread attention.In recent years,the use of nano-zero-valent iron-based materials to remove antibiotics in the environment has been continuously reported.After decades of development,the preparation and modification technology of n ZVI has become increasingly mature,but the agglomeration,stability and reaction efficiency of nano-particles are still problems that hinder its engineering application.In this study,diatomite modified mesoporous molecular sieve MCM-41 was used as the carrier,and nickel was doped with metal to support nano-zero-valent iron.The new composite material n ZVI/Ni/MCM-41 was prepared by the liquid-phase reduction method and used for The removal of two typical antibiotics,tetracycline(TC)and oxytetracycline(OTC)in aqueous solution,study the influencing factors in the removal process,and explore its adsorption catalytic degradation performance and mechanism.Scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),specific surface area(BET)and Fourier infrared spectroscopy(FI-TR)were used for the composite material n ZVI/Ni/MCM-41.Characterization.It can be seen from SEM that the dispersibility of the nano-bimetal is improved after loading,and the agglomeration phenomenon is greatly alleviated.According to XRD analysis,it can be seen that n ZVI was successfully loaded without being oxidized,but the characteristic peak of Ni is not obvious.XPS results further prove that both n ZVI and Ni are successfully Loaded on the carrier;BET characterization found that the specific surface area of n ZVI/Ni/MCM-41 reached174.0563m²/g;from the XRD and FI-TR patterns before and after the reaction of n ZVI/Ni/MCM-41 with antibiotics,it can be seen that zero-valent iron With the characteristic peak of iron oxide,it can be seen that the loading condition is good.After the antibiotic is processed,iron oxide is produced on the surface of the material.The test results of removing TC by composite n ZVI/Ni/MCM-41 show that the best condition for removing TC is that the iron-nickel ratio of the material is 20:1,the dosage is 0.5 g/L,and the optimal initial concentration of tetracycline is 50 mg/L.,The optimal p H value is 6.5.Under the best conditions,the highest removal rate can reach more than 99%.In addition,Ca²⁺and K⁺have almost no effect on the removal efficiency,while H₂PO₄^-and NO₃^-have obvious inhibitory effects.The test results of removing OTC from the composite material n ZVI/Ni/MCM-41 show that the best condition for removing OTC is that the iron-nickel ratio of the material is 20:1,the dosage is 0.2 g/L,and the best initial concentration is 50 mg/L.The optimal p H is 4.2.Under the best conditions,the maximum removal rate can reach about 99%.Ca²⁺has a serious inhibitory effect on removal,and the higher the concentration,the more serious the inhibition.K⁺has almost no effect,and H₂PO₄^-and NO₃^-also have obvious inhibitory effects.The kinetic analysis shows that the degradation of TC and OTC by n ZVI/Ni/MCM-41 is more in line with the pseudo-second-order kinetic model;the adsorption isotherm model analysis shows that the adsorption process of n ZVI/Ni/MCM-41 on TC conforms to the Freundlish model,indicating It is multi-molecular layer adsorption;n ZVI/Ni/MCM-41 is not ideal for the OTC isotherm adsorption process using the Freundlish and Langmuir models.Through LC-MS analysis,it is known that there are 7 and 4 main intermediate products of TC and OTC respectively,and the possible degradation pathways are proposed through the degradation products.