Catalytic Ozonation Of Organic Pollutants Over Fe-based Magnetic Composite Oxides

Water pollution with pesticide and medicine has become a serious problem in china. Catalytic ozonation is one of the efficient methods to deal with these toxic organic pollutants in water. Heterogeneous catalytic ozonation technology has some advantages, such as: high efficiency, high rate, no secondary pollution 、 easy separation of catalyst, continuous operation, reasonable cost and so on. Therefore, this technology attract more attention in water treatment technology in recent years. Magnetic materials that can be easily separated and recycled by applyingan appropriate magnetic field have been extensively studied as environmentally friendly and inexpensive catalysts for water treatment. In this dissertation, two kinds of nano-composite oxides were prepared and investigated as catalysts for catalytic ozonation organic pollutants in water. The results are listed as follows.(1) Preparation and catalytic ozonation performance of Fe3O4/Ce O2Magnetic material Fe3O4/Ce O2 was synthesized and characterized by X-ray diffraction, electron microscope and magnetometer. The material consisted of nanopartilces with weak magnetic property. The introduction of Fe3O4 increased the surface area and positive charge density of Ce O2. 2,4-D and Antipyrine were selected as the target pollutants to investigate the catalytic performance of this material. The result shows that this material exhibited a high catalytic activity over a wide p H range. Moreover, it exhibited good stability during the cycle experiment. Mechanism studies indicate that this catalyst promoted O3 decomposition into hydroxyl radicals. The hydroxyl radicals played an important role for the degradation of organic molecules.(2) Fe3O4/Ce O2 was synthesized by an impregnation-precipitation method. The product was characterized by X-ray diffraction, electron microscopy and magnetometer measurements. The results indicated that the products are spheroidal nanopartilces with weak magnetic property. The composite oxide was found to be an effective heterogeneous catalyst for the mineralization of 2,4-D in aqueous solution with ozone. The TOC removal efficiencies were above 80% over a wide p H range. This heterogeneous catalytic ozonation process should mainly follow a radicalmechanism. The catalyst could accelerate the decomposition of ozone into ?OH. Fe3O4/Ce O2 exhibited excellent catalytic activity and stability for the mineralization of 2,4-D.(3) The catalytic performance of the two catalysts for ozonation of pharmaceuticals such as Ibuprofen, Acetaminophen, Diphenhydramine and Aspirin, was further investigated. The results show that the two catalysts exhibited high catalytic activity for degradation of these four refractory organics. And under the same conditions, the catalysts exhibited the highest activity for Dip Henhydramine. Besides, we studied the effect of p H value, catalyst dosage and pollutant concentration on the degradation of Dip Henhydramine. The reaction parameters were optimized.