US-EGYPT Cooperative Research: Polycyclic Aromatic Hydrocarbon Degradation by Nanostructured TiO2 Thin Films

0809174 ShahDescription：该项目支持特拉华大学纽瓦克分校材料科学与工程系S.Ismat Shah博士的合作研究。埃及的合作者是埃及开罗埃及石油研究所的艾哈迈德·阿布·盖特博士。他们计划研究多环芳烃(PAHs)的降解。该项目包括对合成过程、改性材料的表征和降解机理的系统研究。多环芳烃是一组100多种化学物质，当化石燃料在导致不完全燃烧的条件下使用时会排放出这些化学物质。一些多环芳烃是制造出来的。它们是无色、白色或淡黄绿色的固体。多环芳烃会影响人体免疫系统(这种影响只在动物身上得到证实)，是已知的致癌物质。除了它们在空气中的存在外，它们还间接地从大气中或直接通过工业废物进入水系统。这项提议描述了一种方法，通过这种方法，一种经过试验和测试的材料二氧化钛(二氧化钛)将以一种独特的形式(纳米结构薄膜)使用，这将使二氧化钛的已知特性得到更有效地利用，以降解水中的多环芳烃。块状二氧化钛只能在紫外线(UV)下工作。如果想要自然降解，二氧化钛必须进行改性，以便更大部分的阳光--可见光--能够得到利用。该项目的核心是对二氧化钛进行修饰，以形成对可见光敏感的结构。知识价值：这项建议描述了在半导体金属氧化物组成的光催化剂存在下，水中多环芳烃(PAHs)的光降解的详细研究。多环芳烃是致癌物质，存在于空气和水中。它们主要是由化石燃料的不完全燃烧产生的。光催化剂(二氧化钛)将是薄膜的形式，这种薄膜的制造使其与衬底(如玻璃等)有很强的粘附性。将使用的薄膜工艺包括溶胶凝胶法、金属有机化学气相沉积(MOCVD)和脉冲激光沉积(PLD)。利用高效液相色谱分析示踪光解中间产物，并利用紫外光和可见光研究不同时间、不同光照强度的样品的降解反应路径。将使用包括衍射、显微镜和光谱方法在内的各种技术对催化剂进行广泛的表征。此外，催化剂的组成将根据存在的物相(锐钛矿/金红石)进行优化，或者在主要的二氧化钛催化剂中添加掺杂剂，特别是氮气，以提高其光催化活性。纳米结构在二氧化钛薄膜中的存在是本研究的独特之处。实验将利用纳米材料比块体材料提供的额外优势，即更高的比表面积，存在更活跃的亚稳相，以及更适合于光催化的修饰的能带结构。更广泛的影响：该项目解决了一个对环境和健康产生重大影响的问题。埃及和美国科学家和工程师之间的合作将对双方都有利。几名美国和埃及的本科生和研究生将参与拟议中的工作。国际和平协会成功地与埃及同行合作，包括出版了几份联合出版物。该项目得到了美国-埃及联合基金计划的支持。

0809174ShahDescription: 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.