| Titanium dioxide nanoparticle is a broad prospect in water treatment and other aspects of green material because of its non-toxic, harmless, non-corrosive, strong oxidation ability, high photocatalytic activity and no secondary pollution, etc. Since Ti O2 photocatalyst has some drawbacks that it is difficult to separate and recycle, and cannot be reused continuously, etc, and the supported Ti O2 photocatalyst has difficult to layout the light source, and reduction in catalytic efficiency problem, etc. It is the focus of research that preparation of shell@shell@core structure magnetic photocatalyst with high photocatalytic efficiency and good recovery of magnetic properties.There are two main forms that preparation of shell@core structure magnetic Ti O2 photocatalyst. First, the magnetic core(iron oxide) surface is directly loaded Ti O2. Since the magnetic core contact with Ti O2 directly, the structure will produce light-induced dissolution, resulting in dissolution of the magnetic core and falling photocatalytic activity. To overcome these shortcomings, the surface of the magnetic core of coating an inert isolation layer, preparation of shell@shell@core magnetic photocatalyst to prevent nuclear magnetic direct contact with Ti O2 and the proliferation of magnetic core material, thus reducing the impact on the photocatalytic activity of Ti O2.However, the preparation of shell@shell@core structure magnetic photocatalyst, common synthetic methods require calcination or drying which Ti O2 firmly supported surface of the magnetic core, currently. This leads to cumbersome preparation steps, the material forming low, prepare costly and difficult practical application. Meanwhile, after drying grind, the powder shell@shell@core structure magnetic photocatalyst is destroied its structural integrity, resulting in a sharp decline in the photocatalytic activity; the magnetic photocatalyst without grinding, whether mechanical or ultrasonic agitation shock, were unable to make it effective dispersion, seriously affecting the photocatalytic efficiency. Loaded inert isolation layer on the surface of magnetic nanoparticles, and then was prepared to have a magnetic fluid photocatalysis, the state will be able to overcome the magnetic powder photocatalyst poor dispersion properties and preparation process cumbersome shortcoming.Polyaniline(PANI)@ferrite polymer nanocomposites has magnetic properties which can easily be magnetic separation. More importantly, PANI has electrical conductivity and excellent antioxidant performance at the same time, compared with the single ferrite, PANI/ferrite polymer nanocomposite reduce opportunity to direct contact with each other and dispersion increased dramatically in the solution.In this paper, prepared in situ synthesis PANI@ferrite magnetic composites, and Ti O2 supported on magnetic materials, the Ti O2@PANI@ferrite magnetic fluids photocatalytic were prepared by low-temperature hydrothermal method, inspecting its photocatalytic activity and magnetic recovery performance. And discussed its phase composition, surface topography, surface property, magnetism and particle size by XRD, FT-IR, SEM, TEM, VSM and laser particle analyser. To 100mg/L of phenol to simulate pollutant, the photocatalytic activity is determined respectively by the reaction rate constant K values for degradation of phenol and the degradation rate of COD, and combined with the magnetic recovery equipment, study the life of magnetic photocatalytic activity. Through experiments, this paper obtained the following conclusions:(1) By varying the different reaction conditions, attempting to prepare several PANI inert spacer layer, the photocatalytic activity is determine the best method for preparation of PANI. With the different titanium source for raw materials prepared Ti O2@PANI@Fe3O4 magnetic fluid photocatalysis by the photocatalytic activity of the magnetic properties of the experimental recovery chooses the optimal photocatalytic magnetic fluid. Preparation of the Ti PF as a source of titanium of titanium sulfate has optimal photocatalytic activity of photocatalytic degradation of phenol magnetic fluid reaction rate constant K=0.0097min-1, degradation rate of COD reached 43.68 percent at 120 min, after repeated 5 times, Ti PF degradation phenol reaction rate constant K decreased by 0.0039. TPF magnetic fluid photocatalytic as a source of titanium of tetraisopropyltitanate has the best source for preparing the photocatalytic activity of titanium degradation of reaction rate constant K= 0.0114min-1, the degradation rate of COD reached 43.16 percent at 120 min, after repeated 5 times, TPF phenol degradation rate constant K decreased by 0.0031.(2) The photocatalytic effect of Ti O2@ferrite which coating the Ti O2 coated onto magnetic core directly is far below the Ti O2@PANI@ferrite. This shows that adding the inert isolation layer can successfully avoid direct contact of the Ti O2 and the magnetic core, and prevent corrosion and optical light dissolves and other problems, and improve the photocatalytic efficiency.(3) Comparison of three different materials as the ferrite magnetic core material, photocatalytic activity of the prepared Ti O2 photocatalyst is optimal with the Mn Fe2O4 magnetic core. TPM magnetic fluid photocatalytic degradation of phenol reaction rate constant K=0.0225min-1, the catalytic activity is only slightly lower than pure Ti O2, after repeated 5 times, the reaction rate constant decreased by only 0.0034.(4) Using low-temperature hydrothermal method(180℃, 18h) prepareted of Ti O2@PANI@Mn Fe2O4 photocatalytic magnetic fluid which Mn Fe2O4 as a magnetic core, PANI as inert isolating layer. Synthesized different magnetic photocatalysts in different conditions such as different molar ratio of titanium, aniline and Mn Fe2O4 and select the optimal photocatalytic magnetic fluid. The results show that TPM-16 photocatalytic magnetic fluid [n(Ti4+):n(ANI):n(Mn Fe2O4)=16:1:1] has a good photocatalytic activity and magnetic recovery performance degradation of phenol reaction rate constant K=0.0225min-1, the degradation rate of COD reached 76.27% at 120 min. TPM-16 photocatalytic magnetic fluid through using five times after phenol degradation rate constant only dropped 0.0034.(5) The photocatalytic activity of Ti O2 magnetic fluid photocatalytic is superior after washing, filtration, drying powder form, grinding photocatalyst powder form which is due to poor dispersion of the photocatalyst, reunion serious impact on their photocatalytic activity. Photocatalytic magnetic fluid not only to avoid the state of magnetic powder photocatalyst preparation process cumbersome and costly problems, but also to solve the conventional magnetic Ti O2 catalyst in the reaction system contained the problem of poor dispersion. While maintaining high catalytic efficiency advantages Ti O2 suspension system, and they can be recycled using magnetic. |
PDF Full Text Request