Sonochemical Preparation Of Magnetic Halloysite Nanotubes And Its Catalytic Performance In Heterogeneous Fenton System

In this paper,we have successfully synthesized Fe3O4 on HNTs with HNTs as the support,and prepared the heterogeneous catalyst magnetic halloysite nanotubes(Fe3O4@HNTs).Considering the influence of preparation conditions,different samples were prepared under different ultrasonic temperature,ultrasonic time and dosage of HNTs.The changes of adsorption and catalytic properties were detected by methylene blue(MB)removal experiment.At the same time,the samples were characterized by transmission electron microscopy(TEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and specific surface area(BET)to explore the physical and chemical properties of the materials and select the appropriate preparation conditions.At the same time,the ultrasonic chemical method of Fe3O4@HNTs was used to remove MB,compared with the traditional coprecipitation method,and the mechanism and reusability of Fe3O4@HNTs in heterogeneous Fenton system were explored.Finally,the effects of different anions,carboxylic acids and BTCA on the removal of pollutants in heterogeneous Fenton system and the ability of Fe3O4@HNTs to remove other dyes and aniline in heterogeneous Fenton system were studied.The main research results are as follows:(1)Fe3O4@HNTs was successfully prepared by ultrasonic chemical method.Considering the catalytic performance,time cost and economic cost,the preparation conditions were determined as ultrasonic temperature 60?,ultrasonic time 1 h and the dosage of HNTs 0.5g.TEM characterization results show that the spherical Fe304 is dense and evenly distributed on the surface of HNTs,with a diameter of 10-22nm,indicating that the introduction of ultrasound greatly reduces the agglomeration of Fe3O4 and makes it more evenly dispersed on the surface of HNTs.XRD analysis showed that the dehydration process occurred under HNTs ultrasound,and it was proved that the increase of temperature,ultrasonic time and the amount of HNTs can prevent the further agglomeration of Fe3O4 during the preparation process.At the same time,XRD and XPS analysis showed that Fe3O4 was successfully synthesized on HNTs,BET showed that Fe3O4@HNTs had good microporous and mesoporous structure.By comparing the catalytic ability of Fe3O4@HNTs prepared by traditional coprecipitation method and ultrasonic chemical method,it is found that the removal rate of MB by Fe3O4@HNTs prepared by the latter is twice that of the latter in heterogeneous Fenton system,which shows that ultrasonic chemical method can effectively improve the catalytic performance of catalytic materials.(2)The degradation mechanism of pollutants was studied,the degradation of MB is related to ???*transition and the destruction of conjugated structure.The degradation of MB may be due to the destruction of dimer and the decomposition of benzene ring,but not to the hydroxylation of benzene ring.EPR results show that Fe3O4@HNTs can catalyze H2O2 to produce a large number of hydroxyl radicals(·OH)and superoxide radicals(·O2-).(3)Different anions and carboxylic acids have different effects on the removal of pollutants.SO42-has no effect on the removal of MB.The presence of Cl-and NO3-reduces the removal rate of MB,while the presence of CO32-accelerates the removal rate of MB.The addition of EDTA can reduce the removal rate of MB,the addition of citric acid,potassium oxalate,potassium acetate and potassium sodium tartrate can accelerate the removal rate of MB,and butane tetracarboxylic acid can also reduce the removal rate of MB due to the reaction with H2O2.At the same time,Fe3O4@HNTs has a good removal effect on other pollutants in dye wastewater in heterogeneous Fenton system.For example,the removal rate of malachite green(5 mg/L)is 100%in 20 minutes,and the removal rate of aniline(10 ?g/ml)is 85%in a short time.In conclusion,this paper not only explores the suitable conditions for the preparation of Fe3O4@HNTs by ultrasonic chemical method in practical use,solves the problems of the traditional preparation process of reaction conditions and raw materials,but also develops the application of Fe3O4@HNTs in heterogeneous Fenton system.The ability and removal mechanism of Fe3O4(?)HNTs in the treatment of dye wastewater under complex conditions are preliminarily explored,which provides theoretical support and guidance for its practical application in the future.