Study On The Immobilization Of Nano-TiO₂ On Diatomite By Hydrolysis-Deposition Method And The Performance Optimization Of Composite

Immobilization of TiO₂ nanoparticles onto carrier can prevent the aggregation of TiO₂ nanoparticles and enhance their photocatalytic activities.In this paper, the TiO₂ nanoparticles were immobilized on diatomite by hydrolysis-deposition method successfully.The appropriate pretreatment process was selected and the properties was characterized by XRD, SEM, FT-IR spectroscopy, TG-DSC. And then, the optimum process conditions of nano-TiO₂/diatomite composite were studied by four factors, nano-TiO₂ loading amounts, molar ratio of [Ti4⁺]/[SO₄^2-], calcinations temperature and calcinations time.The optimum process conditions in this experiment were determined by using the single factor and orthogonal experiments. The optimization conditions for nano-TiO₂/diatomite composite are 33.3% of nano-TiO₂ loading,3:1 of [Ti4⁺]/[SO₄^2-,650 ℃ of calcinations temperature and 3 h of calcinations time. Besides, under the condition of 15 W 365 nm UV lamp to 12h, the degradation rate of MB are 90%.The research of SO₄^2- ions on the crystal structure and adsorption-photocatalytic performance of TiO₂/diatomite composite were characterized by XRD, BET surface area, SEM, FT-IR spectroscopy, XPS and UV-vis drs. Besides, the influence mechanism of SO₄^2- ions to TiO₂/diatomite composite was proposed. The nano-TiO₂ consumed the Si-OH structure and formed Ti-O-Si bond on the surface of diatomite in order to enhance the binding force between nano-TiO₂ and diatomite by calcinations. And, The suitable amount SO₂42- ions may capture photogenerated electrons, resulting the formation of oxygen ionosorption （·O₂-） and enhance the photocatalytic activity of TiO₂/diatomite composite photocatalyst.The effect of formaldehyde concentration and relative humidity on the degradation of formaldehyde and dynamics were studied, respectively. The relative humidity has a great influence on the degradation of HCHO, The photocatalytic process follows the typical of Langmuir-Hinshelwood model. The apparent rate constant is calculated according to the kinetic model. The reaction rate constant is 0.1742 mg/m³h, and the adsorption coefficient is 2.0271 m³/mg.