Synthsis And Study On Catalytic Behavior Of Titanium Dioxide/nano Ferrite Composites With Core-shell Stucture

For the high photocatalytic activity,excellent chemical stability,non-toxic to organisms,rich sources of raw materials,Low prices,etc,Anatase TiO2 nanoparticles(TiO2)is expected to have broad application in photocatalytic degradation of industrial organic wastewater,et al,but it is not easy to separate the TiO2 nanoparticles from the degradation system due to small particle size,whitch limits its industrial application.Magnetic photocatalyst,possessing nano-magnetic nuclear and TiO2 shell,exhibits both the recyclable property and photocatalytic performance.In this paper,the nanoferrites MFe2O4 and composite photocatalytic NiFe2O4@TiO2,NiFe2O4 @SiO2@TiO2 nanoparticles were prepared via the sol-gel method.The compositions,microstructures,photocatalytic behavior and recovery performance of the magnetic core and composite photocatalyst were analyzed and discussed.The conclusions are as follows:1.The obtained nanoferrites MFe2O4(M = Ni,Co,Mg,Cu and Ca)belong to the spinel ferrite with small particle size and well-dispersed properties,crystal size of them fluctuats from 28.2nm to 34.3nm when calcinated at 800?,NiFe2O4,CoFe2O4 and CuFe2O4 nanoferrites could not degrade the methyl orange,while the degradation percentage of MgFe2O4 and CaFe2O4 on methyl orange for 180 min were 5.0%and 7.4%,respectively.When Ms value is large,the nanoferrites can be efficiently recycled only by applying a small external magnetic field;For the nanoferrites to be determined,the magnetic induction intensity B increases with the increase of heat treatment temperatures,and the magnetic recovery percentage is higher;2 As for single shell structure of NiFe2O4@TiO2 and NiFe2O4@SiO2,double shell structure of NiFe2O4@SiO2-25@TiO2-37.5 composites,the main phases of them are spinel NiFe2O4,anatase TiO2,and amorphous SiO2;it had no obvious reaction and between NiFe2O4 nuclear magnetic and TiO2 shell;When the amount of SiO2 is 25ml,that of TiO2 is 37.5ml,the obtained single shell NiFe2O4@ TiO2-37.5 and NiFe2O4@SiO2-25,double shell NiFe2O4@SiO2-25@TiO2-37.5 composites possess the excellent coating results,the average particle size of them are about 30 nm,45 nm and 55nm,respectively.3The initial visible-light degradation percentage of single shell structure NiFe2O4@ TiO2-37.5 and double shell structure of NiFe2O4@SiO2-25@TiO2-37.5 composites for the methyl orange are 98.3%and 95.6%,respectively,the first magnetic recovery percentage of them are 94.1%and 93.6%,respectively;After 10 cycles,the decline of the photodegradation percentage of them are 8.8%and 5.2%,respectively,and the decline of the recovery percentage are 3.7%and 2.3%,respectively;The middle layer of SiO2 can effectively block the photogenerated electron-hole migration and combination form TiO2 to NiFe2O4,and can improve the amount of electrons and holes transferred to the surface of TiO2,which can increase the catalytic efficiency of nano composites,and helps to maintain the magnetic stability of NiFe2O4.