This project supports collaborative research by Dr. S. Ismat Shah, Department of Materials Science and Engineering, University of Delaware-Newark. The Egyptian collaborator is Dr. Ahmed Aboul Gheit of the Egyptian Petroleum Research Institute, Cairo, Egypt. They plan to study Polycyclic Aromatic Hydrocarbons (PAHs) degradation. The project includes a systematic study of the synthesis process, characterization of the modified materials, and the degradation mechanism. PAHs are a group of more than 100 chemicals that are emitted when fossil fuels are used under conditions that lead to incomplete burning. Some PAHs are manufactured. They are colorless, white, or pale yellow-green solids. PAHs affect body immune system (effect confirmed only in animals) and are know carcinogens. In addition to their presence in air, they also make their way into the water systems either indirectly from the atmosphere or directly through the industrial waste. This proposal describes a methodology through which a tried and tested material, titanium dioxide (titania), will be used in a unique form (nanostructured thin film) which will allow the known properties of titanium dioxide to be exploited more efficiently for the degradation of PAHs in water. Bulk titania works only with the ultra-violet (UV) light. If natural degradation is desired, titania has to be modified so that the larger portion of the sunlight, the visible light, could be made useful. The heart of the project is to modify titania such that a structure could be formed that is sensitive to visible light.
Intellectual Merit: This proposal describes a detailed study of photodegradation of Polycyclic Aromatic Hydrocarbons (PAHs) in water in the presence of a photocatalyst composed of semiconductor metal oxides. PAHs are carcinogens and are present in air and in water. They emanate primarily from incomplete combustion of fossil fuels. The photocatalyst (TiO2) will be in the form of thin films that are fabricated such that there is strong adhesion with the substrates, e.g., glass, etc. The thin film processes to be used include sol-gel, metalorganic chemical vapor deposition (MOCVD), and pulsed laser deposition (PLD). The photodegradation intermediates will be traced using high performance liquid chromatography analysis and degradation reaction path will be studied for samples irradiated at different periods with different irradiation strengths using UV and visible light. Extensive catalysts characterization will be carried out using various techniques including diffraction, microscopy and spectroscopy methods. Furthermore, the composition of the catalyst will be optimized for the phases present (anatase/rutile) or with the addition of dopant, particularly nitrogen, to the principle TiO2 catalyst to enhance its photocatalytic activity. The presence of the nanostructure in the TiO2 thin film form is the unique aspect of this study. Experiments will exploit the additional advantages the nanomaterials provide over bulk material, namely higher surface area, presence of more active metastable phases, and modified band structure better suitable for photocatalysis.
Broader Impacts: The project addresses a problem of significant environmental and health impact. The collaboration between Egyptian and US scientists and engineers will be beneficial to both sides. Several U.S. and Egyptian undergraduate and graduate students will be involved in the proposed work. The PI has successfully worked with his Egyptian counterparts, including publishing several joint publications. This project is being supported under the US-Egypt Joint Fund Program.
