Study On The Synthesis Of Magnetically Separation Photocatalyst And Photocatalytic Activities

Nanosized TiO2has acctracted wide attentions from researchers in the fields of environment and material science due to its low toxicity, long-term chemical stability, low cost and high photocatalytic activity for mineralization of pollutants. Study on preparation, modification and application of TiO2is developing rapidly. Many researchers have focused on the degradation of organic pollutants in water due to the severe water pollution. Typically, a photocatalytic reaction is conducted in a suspension of powder TiO2because of its high surface area and good dispersibility. Although it has been proven that most organic contaminants in water can be effectively mineralized under UV irradiation, efficient recovery of the small size TiO2from treated water is still a challenge, which prevents its widespread application. Removing such tiny particles from large volumes of water involves further expense. Even though the preassembly TiO2nanoparticles on an appropriate substrate may partially solve this problem, a high dispersibility and a good manipulability of TiO2nanocrystals were the premises of some important applications.Magnetic separation realizes a very convenient approach for removing and recycling magnetic particles by applying appropriate external magnetic fields, without the need for further downstream treatment processes. The incorporation of magnetic components into TiO2nanoparticle-based catalysts can improve the efficiency of separation and recovery of nanosized TiO2.In this study, magnetically separable photocatalysts with UV light activity have been prepared through the combination of the nanosized magnetic particles and nanosized photocatalyst particles. The morphology and structure of the samples have been characterized using analytical techniques of XRD, SEM, TEM, DRS, FT-IR, etc. Furthermore, the photocatalytic activity of prepared catalysts was detected by degradation simulated polluntants Rodanmin B and Orange2. This thesis is composed of three parts as follows:1. The approaches for the preparation of uniform Fe3O4particles had been explored. Ferric trichloride (FeCl3(?)6H2O), sodium acetate (NaAC), sodium citrate (Na3Cit) and ethylene glycol (DEG) were used as reactants and highly dispersed and uniform Fe3O4particles with diameter of200nm were prepared.2. Fe3O4@SiO2was prepared by Stober method and TiO2was loaded on the surface of SiO2. The influence of titania sources of titanium tetrabutoxide (TBOT) and titanium isopropoxide (TTIP) to the photocatalytic activity was studied. The high hydrolysis rate of titania sources led to the difficulty on regulation of the loading amount of TiO2, which can be improved by modifying the particle surface of Fe3O4@SiO2with-SH or-NH2groups.3. We expected to prepare magnetically separable photocatalyst Fe3O4@SiO2@TiO2with chamber structure using Fe3O4@SiO2as the core, but the results showed that the core Fe3O4particles were dissolved under strong acid condition. In hence, we obtained hollow core-shell structure of SiO2@TiO2and studied influence of the additives of ethylene glycol and ammonium sulfate to the morphology and crystal form.