The Environmental Photochemistry Behavior Of Naphthalene On The Surface Of Oxide Hollow Structure

Polycyclic aromatic hydrocarbons (PAHs) are a series of multi-ringed organic compounds. They are produced mainly from incomplete combustion of fossil fuels, volcanoes, forest vegetation and bush burning, terrestrial, aquatic plants and microorganism biosynthesis. Therefore, PAHs ubiquitously and widely distribute in the environment, so people could intake PAHs through the atmosphere, water and food. With the development of science and technology, people come to understand the dangers of PAHs. The most dangerous hazard of PAHs is that photo-induced toxic effects will take place when they exposed to ultraviolet radiation in sunlight. Therefore the research on the photochemical behavior of PAHs is of great importance. In this thesis, we investigate the direct degradation of naphthalene and the photochemical behavior of naphthalene onα-Fe2O3 and TiO2 under UV irradiation. The following investigations have been carried out:First, the morphology of inorganic materials has great influence on their various performances and application. In this paper, we use hydrothermal method to fabricateα-Fe2O3 with yolk-double shells and tubular structures by changing the solution concentration and reaction time. The principles of these hollow structures are the preferential adsorption of PO43-and the cooperative effect of PO43- and SO42- withα-Fe2O3. The morphology and optical properties of the obtained materials are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible absorption spectroscopy (DRS), surface photovoltage spectroscopy (SPS) and other modern characterization techniques.Second, a FTIR spectrometer (Bruker VERTEX 70) equipped with a DTGS detector was used to measure the photochemical behaviors of naphthalene. Experimental results show that under single UV irradiation only, the naphthalene is first converted into 1,4-butanediol and benzene. Three intermediates have been observed during the reaction, they are poly (1,4-butanediol),1,3-butadiene and 1,4-butanediol, where poly (1,4-butanediol) and 1,3-butadiene may be further mineralization to carbon dioxide and water.Third, a FTIR spectrometer was used to study the photochemical behaviors of naphthalene, which adsorbed on the surface ofα-Fe2O3. Experimental results show that under UV irradiation, the naphthalene first transformed into o-phthalaldehyde, and then o-phthalaldehyde rapidly converted into phthalic acid. Phthalic acid was detected as the intermediate in our experiments. The condensation reaction takes place between the two hydroxyl of phthalic acid, and the phthalic acid be converted into phthalic anhydride finally. Therefore, the intermediate product is phthalic acid and final products are phthalic anhydride, carbon dioxide and water.Fourth, template method was used to fabricate CaCO3/TiO2 hollow structural. The characterization results show that the morphology of the samples is hollow bead with good dispersion.Finally, a FTIR spectrometer was used to study the photochemical behaviors of naphthalene which adsorbed on the surface of CaCO3/TiO2 hollow beads. Experimental results show that the main intermediate product is phthalic anhydride and final products are carbon monoxide, carbon dioxide and water.