Preparation Of Ferric Oxide/XDA-7 Catalyst And Study Of H₂O₂ Oxidation Antibiotics

With the rapid development of economy and medical technology and people’s unreasonable use of antibiotics,the water environment problems caused by antibiotic pollution occurred frequently in recent years.With the improvement of detection level,the presence of antibiotics had been detected in all water bodies around the world.Antibiotics were enriched in water,which would re-enter the human body through drinking water and harmed human health.In recent years,antibiotic resistance genes had been discovered one after another,which is more alarming to people.Therefore,the problem of antibiotics in water environment needs to be solved urgently,and an efficient method to remove antibiotics in water environment is particularly important.In this study,an alkaline coprecipitating method was used to prepare resin（XDA-7）supported iron oxide catalyst.This study took the typical antibiotics ceftriaxone sodium and tetracycline hydrochloride in the water environment as the research objects.Heterogeneous Fenton catalytic oxidative degradation experiments were carried out.The effects of initial solution concentration,catalyst dosage,temperature,p H and H₂O₂ concentration on the degradation reaction were investigated and the reaction mechanism was explored.（1）Supported catalyst iron oxide/XDA-7 was prepared by using XDA-7 anion resin as the carrier and supported by alkaline coprecipitating method.Scanning electron microscope,energy spectrum analyzer,specific surface area tester,X-ray diffractometer,Fourier infrared spectrometer and X-ray photoelectron spectrometer were used to analyze the morphology,functional groups and valence states of the supported metal elements on the catalyst surface,respectively.The results showned that the iron oxide was loaded on the resin successfully,and the iron loaded was7.64%.（2）Experimental study on heterogeneous Fenton catalytic oxidation of ceftriaxone sodium was carried out by using iron oxide/XDA-7.The effects of catalyst dosage,H₂O₂ concentration,initial p H of reaction solution,initial concentration of solution and temperature on the removal of ceftriaxone sodium were investigated.The results showed that the removal rate of ceftriaxone sodium increased with the increase of temperature,catalyst dosage and H₂O₂ concentration.When the iron oxide/XDA-7 catalyst dosage was 667 mg/L,the oxidant H₂O₂ concentration was6.6 mg/L,the initial concentration of ceftriaxone sodium was 10 mg/L,the temperature was 25°C,and the p H of the solution was 6.18,the removal rate of ceftriaxone sodium could reach 97.79%,and the TOC removal rate could reach82.25%.The removal rate of sodium pine was increased by 41.09%compared with the removal rate of the catalyst alone.After repeated use of the catalyst for 5 times,the removal rate of catalytic oxidation of ceftriaxone sodium decreased only by about5%.And the catalyst still had strong catalytic activity.The addition of inorganic ions and humic acid in water had different inhibitory effects on catalytic oxidation experiments.The addition of tert-butanol obviously inhibited the removal of ceftriaxone sodium,which indirectly indicated that the reaction follows the oxidation mechanism of hydroxyl radicals.By kinetic fitting of the degradation curve under this condition,the reaction process of ceftriaxone sodium oxidation catalyzed by the heterogeneous Fenton method conformed to the second-order kinetic equation.（3）In order to further investigat the catalytic performance of the catalyst,the catalyst was applied to the study of the heterogeneous Fenton method for catalytic oxidation of tetracycline hydrochloride.The results showed that when the initial concentration of tetracycline hydrochloride was 10 mg/L,the dosage of ferric oxide/XDA-7 catalyst was 667 mg/L,the concentration of oxidant H₂O₂ was 6.6 mg/L,the initial p H of the reaction solution was 4.73,the removal rate of tetracycline hydrochloride was 81.934%,and the removal rate of TOC was 74.35%.When the dosage of tert-butanol was 50 mg/L,the catalytic effect of ceftriaxone sodium was reduced by 20.95%.It could be seen that tert-butanol had obvious inhibitory effect on catalytic oxidation.Through the kinetic fitting of the reaction degradation curve under this condition with the first-order kinetics and the second-order kinetics,the comparison shown that the second-order kinetics was better.