Collaborative Research: Degradation Mechanism of Cyanotoxins Using Novel Visible Light-Activated Titania (TiO2) Photocatlysts

合作研究：新型可见光活化二氧化钛（TiO2）光催化剂降解蓝藻毒素的机制智力价值：世界各地河口和淡水水生系统中有害藻华（cyanobacteria - habs）的增加是一个主要的全球性问题。蓝藻有害藻华产生并释放多种具有极高毒性的蓝藻毒素（即肝毒素、皮肤毒素、神经毒素）。作为或可能作为饮用水供应来源的水生系统中高浓度有害蓝藻毒素的存在是对人类和环境健康的严重威胁。传统的水处理技术并不能完全有效地去除这些天然存在的剧毒有机化合物，因此迫切需要开发能够有效去除水中蓝藻毒素的新技术。该提案是在美国研发计划下提交的，旨在开发一种太阳能驱动的高级氧化技术（AOT），作为解决水中蓝藻毒素污染问题的可行方案。光催化是一种利用光激活半导体驱动水中氧化还原过程的AOT，导致有机污染物的破坏和微生物的失活。二氧化钛（TiO2）是最适合水处理的光催化剂；然而，它需要紫外线激发，这意味着只有4%的太阳光谱可以被利用。可见光活性（VLA）光催化剂材料的开发将是有效利用太阳能处理污水的重要一步。非金属掺杂可见光活化（VLA） TiO2材料尤其有前景，因为它们是强可见光吸收剂，并且容易敏化活性氧（ROS）的形成，而活性氧可以降解有毒的有机污染物。目前，有机底物在VLA - TiO2辐照下的化学性质尚不清楚。知识库中的这种差距是一个关键问题，因为它阻碍了这些系统在水处理应用中的优化。这项美国-爱尔兰跨国合作研究涉及来自美国两所大学（一所是少数机构）、一所北爱尔兰大学和一所爱尔兰共和国理工学院的科学家和工程师，目的是阐明可见光辐射或太阳光激活的VLA TiO2催化水中蓝藻毒素降解的机制。核心假设是，VLA TiO2的辐照产生ROS，降解蓝藻毒素，这种反应性可以很容易地通过改变材料的性质和光催化条件来调节。在强有力的初步证据和研究人员的丰富经验的指导下，该假设将通过追求三个具体目标来验证：(1)合成、表征和优化新的VLA TiO2光催化剂，以评估其对水中蓝藻毒素的破坏作用；(2)研究VLA TiO2光催化剂的光电反应；(3)确定VLA TiO2光催化剂的形成、命运、以及在蓝藻毒素存在下，VLA TiO2照射产生的ROS的反应性，确定蓝藻毒素降解动力学，评价氧化产物的生物活性，确定可见光或太阳光激活VLA TiO2光催化剂降解蓝藻毒素的反应中间体和反应途径。这项工作是原创的，因为它侧重于制备和光化学性质易于修改的新材料。所提出的研究具有重要意义，因为它有望为优化水处理的太阳能驱动光催化过程的合理策略的发展提供必要的机械知识。更广泛的影响：研究活动将直接推进发现和理解，同时通过将本科生，研究生，博士后研究人员和pi组成的研究团队聚集在一起，促进教学，培训和学习。该研究计划强调代表性不足的群体参与具有国际规模的科学项目。此外，本科生和研究生将受益于严格的跨学科轮转实验室训练，从而丰富课程。该计划亦会提供机会让学生到海外接受科学训练，从而促进合作实验室之间的思想交流。除此之外，研究成果将用于UC， FIU， UU和CREST-DIT的本科和研究生授课课程（例如纳米技术模块）。总的来说，拟议的活动有望加强所涉及的研究所之间的合作，因此，这些活动与国家科学基金？美国、爱尔兰共和国和北爱尔兰之间最近的纳米技术创新协议。这项研究的更广泛的社会影响包括促进可持续发展和缩小人类生态足迹。从这些研究中获得的知识将指导使用可再生能源开发新的水处理方法。这些见解的应用将加速解决环境问题的相关纳米技术的实施，以及推进太阳能收集的光电化学系统和光催化材料在其他环境应用中的发展，如空气净化、消毒和传感。

Collaborative Research: Degradation Mechanism of Cyanotoxins UsingNovel Visible Light-Activated Titania (TiO2) PhotocatalystsIntellectual merit: The increase of harmful algal blooms by cyanobacteria (Cyano-HABs) in estuaries and freshwater aquatic systems around the world is a major global problem. Cyano-HABs produce and release a variety of cyanobacterial toxins (cyanotoxins) (i.e., hepatotoxins, dermatotoxins, neurotoxins)with extremely high toxicity. The presence of high concentrations of harmful cyanotoxins in aquatic systems that serve or could potentially serve as sources of drinking water supply is a serious threat to human andenvironmental health. Conventional water treatment technologies are not wholly effective for the removal of these highly toxic naturally occurring toxic organic compounds and there is a critical need to develop new technologies which can effectively remove cyanotoxins from water. This proposal, submitted under the USIreland R&D initiative, aims to develop a solar driven advanced oxidation technology (AOT) as a viable solution to the problem of cyanotoxin contamination in water. Photocatalysis is an AOT which utilizes light-activatedsemiconductors to drive redox processes in water, leading to the destruction of organic pollutants and the inactivation of microorganisms. Titanium dioxide (TiO2) is the most suitable photocatalyst for water treatment; however, it requires UV excitation meaning that only 4% of the solar spectrum can be utilized.The development of visible light active (VLA) photocatalyst materials would be a major step forward towards the effective utilization of solar energy for the treatment of polluted water. Non-metal doped visible light activated (VLA) TiO2 materials are especially promising because they are strong visible-light absorbers and readily sensitize the formation of reactive oxygen species (ROS), which are known to degrade toxic organic pollutants. At present, the chemistry of organic substrates in the presence of irradiated VLA TiO2 is not well understood. This gap in the knowledge base is a critical problem, because it prevents the optimization of these systems for water treatment applications. The objective of this United States-Ireland trans-nationalcollaborative study, involving scientists and engineers from two universities in the United States (one being a minority institution), one University from Northern Ireland and one Institute of Technology from the Republic of Ireland, is to elucidate the mechanism of cyanotoxin degradation in water catalyzed by VLA TiO2 activated by visible light radiation or solar light. The central hypothesis is that irradiation of VLA TiO2 produces ROS that degrade cyanotoxins and that this reactivity can be readily modulated by varying the properties of the materials and the photocatalysis conditions. Guided by strong preliminary evidence and the extensive experience of the assembled researchers, this hypothesis will be tested by pursuing three specific objectives:(1) Synthesize, characterize and optimize new VLA TiO2 photocatalysts that will be evaluated for the destruction of cyanotoxins in water, (2) Investigate the photoelectrochemical response of VLA TiO2 photocatalysts, and (3) Determine the formation, fate, and reactivity of ROS generated during irradiation of VLA TiO2 in the presence of cyanotoxins, determine kinetics of cyanotoxin degradation, evaluate the biological activity of the oxidation products, and determine reaction intermediates and reaction pathways ofcyanotoxin degradation using VLA TiO2 photocatalyst activated by visible light radiation or solar light. The proposed work is original because it focuses on the preparation and photochemistry of new materials whose properties are readily modified. The proposed research is significant because it is expected to provide the mechanistic knowledge that is necessary for the development of rational strategies for optimizing solar-driven photocatalytic processes for water treatment.Broader impact: The research activities will directly advance discovery and understanding while promoting teaching, training and learning by bringing together a research team composed of undergraduate students, graduate students, postdoctoral researchers and the PIs. The research plan emphasizes participation of under-represented groups in scientific projects of international dimensions. In addition,undergraduate and graduate students will benefit from rigorous cross-disciplinary rotational laboratory training, thereby enriching the curriculum. The project will also offer opportunities to the student researchers to receive scientific training overseas, thereby facilitating exchange of ideas between the collaborating laboratories. In addition to this, the results of the research will be utilized for undergraduate and postgraduate taught courses (e.g. module in nanotechnology) in UC, FIU, UU, and CREST-DIT. Overall, the proposed activities are expected to strengthen co-operation between the institutes involved, and therefore,these activities are well aligned with the NSF?s international collaboration research objectives and the recent nanotechnology innovation agreement between the U.S., Republic of Ireland and Northern Ireland. The broader societal impacts of this research include enhancing sustainable development and shrinking the human ecological footprint. The knowledge obtained from these studies will guide the development of new water treatment methodologies using renewable energy. Application of these insights will accelerate the implementation of related nanotechnologies in addressing environmental problems, as well as advance the development of photoelectrochemical systems for solar energy harvesting and photocatalytic materials in other environmental applications such as air purification, disinfection and sensing.