Study On Removal Of Levofloxacin Hydrochloride Antibiotic In Water By Heterogeneous GO-MCM-Fe-PS System

In recent years,the widespread application of antibiotics has caused pollution of the water environment and has seriously threatened human health and development.Therefore,how to effectively remove antibiotics in water has become an important issue that China and even the world need to solve.Based on this,a complex catalyst prepared by using graphene oxide?GO?and iron loaded MCM-41 molecular sieves was used to activate persulfate?PS?to remove levofloxacin hydrochloride,and this study provides a theoretical basis and technical support for the solution of antibiotic pollution in water.The research results obtained are as follows:?1?GO-MCM-Fe composite catalyst was prepared by solvothermal method.Scanning electron microscopy?SEM?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,Fourier transform infrared?FT-IR?,Raman spectroscopy?Raman?,specific surface area,and The pore size analysis?BET&SF?technique was used to characterize and analyze the catalyst.It was found that iron and GO were loaded on the molecular sieve,while iron was present in the form of iron oxide in the GO-MCM-Fe catalyst,and was also distributed on the GO,causing GO formation.More ordered sp² hybrid structures have a certain influence on the defects of GO.GO-MCM-Fe possesses the structural characteristics of graphene and molecular sieves.Although the specific surface area is slightly lower than that of MCM-41,it still belongs to a large specific surface area,and the Fe³⁺/Fe²⁺ratio on the surface of GO-MCM-Fe is 1.89.?2?The overall effect of levofloxacin hydrochloride removal in the prepared GO-MCM-Fe catalyst-activated PS heterogeneous reaction system was the best.Activated persulfate method reaction reached 60 min,the removal rate of levofloxacin hydrochloride reached 97.28%,COD removal ratio was 76.48%,and TOC removal rate was 35.36%.Quenching experiments showed that the system has sulfate radical?SO₄·^-?and hydroxyl radical?·OH?,and·OH plays a leading role.The best combination parameters of GO-MCM-Fe catalyst were:5%wt Fe²⁺and 30 mL GO?GO concentration 7.75 mg/L?in 2 g MCM-41.It was found that the different forms of catalyst elements Fe²⁺and GO have different effects on the removal of levofloxacin hydrochloride,and the supported Fe and GO have a synergistic effect on the catalytic performance of the reaction system.In GO-MCM-Fe-PS reaction system levofloxacin hydrochloride was removed,although GO-MCM-Fe reacts with PS to generate new bonds,but still maintain its original performance after repeated use.?3?100 mg/L levofloxacin hydrochloride was removed with GO-MCM-Fe-PS system.The suitable conditions were as follows:the pH range of the system was 3⁹.The reaction system with strong acid and alkali conditions had obvious inhibition effect on the removal of levofloxacin hydrochloride;reaction system with the increase of temperature removal rate increased,but the increase in temperature is not conducive to the stability of the catalyst,so the suitable temperature is 20?;the best oxidant dosage of the reaction system is 0.2g/L,the catalyst dosage for 0.5g/L,the removal rate of levofloxacin hydrochloride reaches 97.10%in 10 min.The study found that Cl^-,HCO₃^-,HPO₄^2-,and NO₃^-had some degree of inhibition of levofloxacin hydrochloride removal to varying degrees;Ca²⁺,Mg²⁺and Al³⁺also had a certain inhibitory effect,and Na⁺had little effect;low concentrations of fulvic acid can promote the removal of levofloxacin,and high concentrations of fulvic acid have inhibitory effects.The addition of small molecule organic acids:CH₃COOH?C₆H₇O₈?H₂C₂O₄ are not conducive to the removal of levofloxacin hydrochloride,and have a certain influence on the stability of the catalyst.?4?The reaction mechanism of this system shows that not only the oxidation of SO4·^-and·OH radicals in the system,but also the chemical reaction on the catalyst surface.FT-IR spectroscopy demonstrated that the?Fe???/?Fe???on the surface of the GO-MCM-Fe catalyst and S₂O₈^2-will have an inner-sphere effect,XPS and Raman analysis demonstrated that the GO-bonded?Fe???after activating PS will oxidized to?Fe???,and then?Fe???restored to?Fe???by rGO,so that the GO-MCM-Fe catalyst maintains high activity during recycling.