Synthesis And Photocatalytic Property Research Of C-TiO₂ Magnetic Nanoparticles

With the increasing serious problem of water environment pollution,it is a hot spot to study the high efficient sewage treatment method.Owning to the effect of the semiconductor photocatalytic under light irradiation,using semiconductor nano-materials photocatalyst to degrade organic pollutants has been attracted more and more attention on purifing polluted water.Among so many kinds of semiconductor materials,the researches about anatase TiO₂ nano-materials are most applied on sewage treatment.However,the wide bandgap make it can only be excited by ultraviolet light while ultraviolet light in the sunlight only a very small portion.The recovery of the nano photocatalysis is another problem need to be solved.This research focuses on the TiO₂ nano-photocatalyst modification.Fe3O4 nanoparticles can absorb visible light because of its narrow band gap,and it is superparamagnetism so that it can be effectively recovered.Therefore Fe3O4 modified TiO₂ nanomaterials are more and more applied as catalyst for wastewater treatment.However,some studies found that the direct modification of Fe3O4 and TiO₂ will greatly decrease the recombination of the electron and hole pairs,which leads to the photocatalytic efficiency decrease.Based on that,this resarch leads a uncompletely layer of SiO₂ in the middle of Fe3O4 and TiO₂ to obtain magnetic C-TiO₂ nanocomposites,and study its photocatalytic property for organic wastewater treatment.The whole research can be summarized as follows:（1）C-TiO₂ nanoparticles were prepared by carbon assisted method,which is a new method.The results show that the anatase TiO₂ nanoparticles were successfully synthesized by carbon-assisted method.A new method,carbon-assisted method,was used to prepare C-TiO₂ nanoparticles.We first use absorbent cotton as a dispersant,fully absorb the n-butyl titanate in oxygen after high temperature calcination of C-TiO₂ nanoparticles.Then the nanomaterials were characterized by TEM,HRTEM,XPS,UV-visible absorption spectra,（Ahv）2-hv curves and nitrogen adsorption-desorption curves.The results showed that the composite was obtained by high-temperature calcination at 500 ℃ with cotton wool and n-butyl titanate for 3 h.The high specific surface area C-TiO₂ nanoparticles with a particle size of about 50 nm and a broad absorption spectrum was prepared in this way.The results showed that C-doped TiO₂ nanoparticles were successfully prepared by carbon-assisted method,and the C-TiO₂ nanoparticles have stronger visible light absorptivity than P25,indicating that C-TiO₂ nanoparticles have stronger photocatalytic ability than P25.（2）A novel magnetic C-TiO₂ nanocomposite with core-shell structure was prepared by the carbon-assisted and sol-gel method.The energy band position of this nanocomposite is narrowed by leading of Fe3O4.The characterization results show that the nanomaterials can be irridated by visible light.Based on thesummary of the researchs about semiconductor nanomaterials,a kind of magnetic C-TiO₂ composite were designed and synthesized.The magnetic Fe3O4 nanomaterial,which can be excited by the visible light and the anatase TiO₂ nanmaterial were compounded.The contact surface of the two materials is not completely separated by SiO₂ layer.This layer do not affect the electron transport between Fe3O4 and TiO₂,and it can effectively preventing the recombination of electrons and holes as well.XRD,XPS,VSM,UV-visible absorption spectra,（Ahv）2-hv curves and nitrogen adsorption-desorption curves were used to characterize the magnetic C-TiO₂ composites.The characterization results show that the magnetic C-TiO₂ composites with high specific surface area and broad absorption can be obtained via the carbon-assisted method and the sol-gel method,and the magnetic compositewith core-shell structure has strong absorption in the visible range.（3）The experimental platform of photocatalytic wastewater treatment based on magnetic C-TiO₂ composites were established,and the photocatalytic performances of C-TiO₂ nanoparticles and magnetic C-TiO₂ nanoparticles were studied.The materials characterization results show that C-TiO₂ nanoparticles and magnetic C-TiO₂ composites both have good photocatalytic activity.Then the photocatalytic activity of C-TiO₂ nanocomposites and magnetic C-TiO₂ nanocomposites were studied by methyl orange,methylene blue and TNT solutions treatment.The results show that the C-TiO₂ nanocomposites can degrade the methyl orange solution under Uv light,and the recoverable magnetic C-TiO₂ nanocomposites can degrade the glucose,ammonium chloride,potassium dihydrogen phosphate,methyl orange,methylene blue and TNT solutions under both Uv can visble light.Then,the recyclability and reusability were tested.