| Due to the excellent photocatalytic properties, TiO2photocatalytic degradation of pollutants has aroused attention from wide rang of scholars home and abroad. Powder photocatalyst has the difficulties of separation, easy to aggregate and can not recycle, some scholars recycled TiO2by loading it on bulk materials (glass, ceramics, metal, etc.) and powder materials (glass beads, active carbon, bentonite, etc.), but all of them caused the problems of the reduced photocatalytic activity and difficult recovery.Coat TiO2on the surface of soft magnetic nano-materials can get the advantages of high powdery catalytic activity and recycling by magnetic field. So far, Magnetic contained TiO2photocatalyst preparation in two ways:The first is directly loading TiO2on the surface of the magnetic core; The second is loading inert insulation layer on magnetic core first, and then loading TiO2to make shell/shell/core structural photocatalyst. Currently, the above mentioned magnetic contained TiO2photocatalyst mostly used heat treatment, however, heat treatment has the defects of reduced photocatalytic activity and magnetic recovery.Polypyrrole (PPY) has the advantages of insoluble and infusible, easy polymerization, acid and alkali resistance, corrosion resistance, good stability, etc. Coat PPY on the ferrite surface to form a dense thin protective layer, and then loading TiO2photocatalyst by the low-temperature method can overcome the disadvantage of the above two ways.In this thesis, a magnetic contained TiO2photocatalysts has been prepared by hydrothermal reaction (170℃, pH=7±0.2), polypyrrole (PPY)-treated nano-Fe3O4is magnetic core. The content of this study can be divided into three parts:(1)The nanometer TiO2photocatalyst was synthesized under the hydrothermal method (170℃, pH=7±0.2) conditions and do further research about the magnetic properties, Investigated the influence of different factors on TiO2to determine the best conditions of preparation of TiO2in the conditions;(2) By chemical oxidation was prepared PPY/Fe3O4magnetic fluid, and to test their physical and chemical properties (3) PPY/Fe3O4as magnetic core, Magnetic contained TiO2photocatalyst was synthesized under the hydrothermal method (170℃, pH=7±0.2) conditions. This photocatalyst prepared by above method has excellent photocatalytic activity and magnetic recovery. The prepared composite particles were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and Zate-potentiostat. The photocatalytic activity of the catalysts were evaluated by photocatalytic degradation phenol, and the magnetic recovery rate were Study by self-make recovery equipment.The results of this study show that the optimal reaction conditions for preparation of pure TiO2reaction time of18h, the system temperature of170℃,n(Ti4+):n(CH3CH2OH): n(H20)=1:10:40under the conditions of catalyst preparedthe highest activity; the PPY/Fe3O4magnetic flux density is maintained at50emu/g, the PPY/Fe3O4with high magnetic recovery performance, PPY/Fe3O4of magnetic recovery rate of up to99.65%; The results indicate that the the samples were mix-crystal TiO2with anatase phase(95.2%) and rutile phase(4.8), and its particle size was4-7rim; PPY can promote TiO2support on the surface of the magnetic core, TiO2support is strong on the surface of PPY/Fe3O4. Catalyst TPF (nTiO2:nPPY:nFe3O4=30:2.1:1) exhibited good shell/shell/core structure and superparamagnetism, and its magnetic induction intensity was40emu/g. The degradation of phenol followed first-order reaction kinetics and the reaction rate constants (K) of Pure TiO2, P25, TPF are0.0279,0.0264,0.0252, respectively, after recycling for5times, the activity of TPF reduced a little(K=0.020), and the average recovery was90.35%. The magnetic composite photocatalyst has high activity and magnetic recyclability, which has good application foreground. So far, no relevant information was reported home and abroad, and this thesis has published in a core journal articles and has applied for national invention patents. |
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