| Environmental pollution and energy shortage are currently two major emergent problems which all people have to deal with. As a green technology, the photocatalysis provides an effective and potential method to completely eliminate the toxic chemicals, with dual roles of the use of natural solar energy and environmental pollution control. It has been an important research topic to develop the new type of photocatalysts with visible light activity. Benzene is one of the typical environmental pollutants. It is a challenging issue to degrade benzene at room temperature and atmospheric pressure for the field of environmental chemistry, because of its very stable chemical structure. In this thesis, to address the scientific issues of improving the visible light utilization and photocatalytic efficiency on the degradation of benzene, several visible light active ferrites micro/nano spheres were prepared via choosing of different metal cations, controling of morphology, construction of composite ferrite systems and further the loading of organic semiconductor materials. The visible light induced photocatalytic activities of these ferrites photocatalysts were evaluated via the photocatalytic degradation of gaseous benzene by using the in situ FTIR technique. In detail, the following investigations were carried out in this dissertation:(1) Spinel CuFe2O4nanospheres with visible light photocatalytic activity were synthesized in high yield. The photocatalytic degradation rate of benzene on CuFe2O4nanospheres was about41.1%in8h reaction and CO2was the product during the reaction process. Ca0.15Fe2.85O4porous microspheres were successfully fabricated and they also showed the performance of photocatalytic degradation of benzene. CO2was produced as the product and the degradation rate of benzene was about43.5%in8h reaction.(2) ZnFe2O4/α-Fe2O3composite hollow micro/nanospheres were successfully fabricated. The degradation rate of benzene on the photocatalyst was about57.9%under visible light irradiation for8h. Benzoquinone, ethyl acetate and CO2were speculated to be products during the reaction, as demonstrated by in situ FTIR. MgFe2O4/α-Fe2O3composite hollow micro/nano spheres were successfully synthesized and they exhibited better photocatalytic activity on benzene degradation. Benzoquinone and CO2were speculated to be the products and the degradation rate of benzene on the composite nanospheres catalysts was about68.1%in eight hours of visible light illumination. (3) PANI modified MgFe2O4/a-Fe2O3composite hollow micro/nanospheres were fabricated by the impregnation method. By using the in situ FTIR technique, aldehyde, carboxylic acid, ethyl acetate and CO2could be speculated as the products of photocatalytic degradation of benzene, while the degradation rate of benzene was about77.2%after photocatalytic reaction of8h on the composite catalysts. The MgFeaO4/α-Fe2O3/PANI composite catalysts demonstrated remarkable improvement over MgFe2O4/a-Fe2O3on the photocatalytic degradation of benzene under visible-light irradiation, which was mainly ascribed to the high efficiency of charge separation induced by the hybrid effect of PANI and MgFe2O4/α-Fe2O3.(4) The ascending order of visible light photocatalytic activity of the ferrites on benzene is found as follows:MgFe2O4/α-Fe2O3/PANI composite hollow micro/nanospheres> MgFe2O4/a-Fe2O3composite hollow micro/nanospheres> ZnFe2O4/a-Fe2O3composite hollow micro/nanospheres>Ca0.15Fe2.85O4porous microspheres>CuFe2O4nanospheres.In summary, a series of new visible light response ferrite catalysts were constructed in this thesis. Not only the efficiencies of visible light utilization and catalytic degradation of benzene were improved, but also the mechanism of photocatalytic degradation of benzene was revealed. These investigations are expected to help promote the photocatalytic technology towards practical application and are of positive significance in the situation of the currently increasing environmental pollution.
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