Preparation And Photocatalytic Performance Of Magnetic Fe₃O₄@TiO₂/SiO₂ Aerogel Catalyst

With the development of industry and agriculture, which cause serious damage to the surrounding environment and can be hardly destroyed with traditional wastewater treatment methods. Therefore, the removal of reactive dyes from aqueous solution is necessary and very important. During the past decades, photocatalytic degradation of organic dyes by using semiconductor nanoparticles is of growing interest for environmental remediation. Among various photocatalysts, titania has been employed widely in the destruction of organic pollutants due to its low cost, excellent chemical stability, non-toxicity and high photocatalytic activity. TiO2 generates electron and hole pairs (e-/h+) upon irradiation with light energy equal to or greater than its band gap energy. If charge separation is maintained, the photo-generated electrons and holes may migrate to the catalyst surface and participate in interfacial redox reactions with sorbed species. However, the utilization of TiO2 nanoparticles in practical applications such as wastewater treatment is impaired by its low capacity for the adsorption of hydrophobic contaminants, the fast recombination of photogenerated electron-hole pairs that limits photo-quantum efficiency, and the inconvenience to separate and recycle of nanometer sized TiO2 particles from water. Therefore, many strategies have been proposed to enhance the absorption capability and photocatalytic activity of TiO2 nanoparticles. Based on TiO2 above disadvantages, we developed SiO2 aerogel with a high specific surface area and Fe3O4 with magnetic response. In the end.we prepared magnetic Fe3O4 @ TiO2/SiO2 aerogel catalyst to improve the ability of adsorption of TiO2 and recycle the composite with permanent magnet. Then we studied the behavior of the composite photocatalytic degradation of organic wastewater. The paper includes the following contents:(1)Firstly, Fe3O4 was obtained using hydrothermal method. Then, we successfully synthesized Fe3O4 @ TiO2 catalyst by sol-gel method. In order to obtain the carrier with high specific surface area, SiO2 aerogel were extracted from fly ash.On this basis, Fe3O4@TiO2/SiO2 aerogel catalyst was successfully synthesized by hydrothermal method(2) The prepared Fe3O4@TiO2/SiO2 aerogel catalyst was characterized by XRD? IR?BET?SEM?TEM?UV-vis. The results demonstrated that a dense TiO2 layer was formed on the surface of Fe3O4.(3)Photocatalytic of Fe3O4@TiO2/SiO2 aerogel catalyst was tested using RhB.The influence of experimental condition such as different catalysts,pH value,initial concentration,catalyst dosage,SiO2 aerogel dosage and TBOT dosage.The results showed that under optimal conditions for preparing and degradation, Fe3O4 @ TiO2/SiO2 aerogel catalyst degradation efficiency of RhB is better than TiO2 The photocatalytic reactions obeyed pseudo-first-order kinetics according to Langmuire-Hinshelwood model.In addition, Fe3O4 @ TiO2/SiO2 aerogel catalyst has a batter recyclability.The integration of functions such as excellent photocatalytic activity, high adsorptivity and magnetic responsivity makes the prepared multifunctional Fe3O4@TiO2/SiO2 aerogel composite material an efficient candidate for removing organic contaminants from water.