Photocatalytic Reduction of Nitrate in Water

光催化还原水中的硝酸盐

• 批准号: 1132779
• 负责人: Paul Westerhoff
• 金额: $ 29.8万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1132779&HistoricalAwards=false
• 关键词: Photocatalytic; Reduction; Nitrate; Water

1132779WesterhoffNitrate (NO3-) is one the most prevalent ground-water contaminants in North America and world-wide. It poses a risk to human health and has a large impact on the natural nitrogen cycle. Nitrate is regulated by the USEPA in drinking water because it is a known cause of methemoglobinemia, or ?blue baby? syndrome, and could possibly be a carcinogen or endocrine disruptor. Nitrate is a soluble ion that is difficult to remove by traditional coagulation or adsorption processes. Risks from oxidized pollutants are best mitigated through chemical or biological reduction to innocuous forms (e.g., N2 from NO3-). Photocatalytic reduction has been reported for decades, yet has not been investigated from an engineering approach for nitrate reduction. Research initiated by the discovery of Honda-Fujishima effect for photocatalytic water splitting (e.g., production of hydrogen as a renewable fuel) and subsequent advances in metal loading of semiconductors suggest that nitrate reduction in near neutral pH without addition of sacrificial agents is possible. Furthermore, it now appears possible that photocatalytic NO3- reduction in water could yield innocuous by-products (N2) instead of undesirable by-products that require additional treatment (e.g., ammonia). Photolysis for disinfection is commonplace in the drinking water industry over the past decade and use of light-based technologies for water treatment will continue to evolve because of their effectiveness, small size footprint, ability to operate without wastestreams, etc. Translational research from the fields of chemistry, material science and physics, where reductive photocatalysts are developed for splitting water, is proposed to be applied towards engineered technologies for nitrate removal from water. The PI?s preliminary data demonstrate the feasibility to photocatalytically reduce nitrate and yield gaseous-N by-products. The goal of this project is to explore and optimize the use of photocatalysts as a reductive technology for treating nitrate in drinking water applications. The underlying hypothesis is nitrate can be converted to innocuous aqueous species in drinking water applications using metal-loaded photocatalysts. The primary research objectives will be to: (1) Understand factors and mechanisms affecting NO3- reduction to N2 for different types of photocatalysts; (2) Apply photocatalyst for NO3- reduction in ion exchange brines and local groundwaters; (3) Investigate practical aspects of photoreactor operation (slurry and fixed film photocatalyst reactors) including role of catalyst ?aging? on catalyst performance in reducing NO3- and catalyst recovery; (4) Screen novel photocatalysts for nitrate and other oxo-anion reduction and develop a framework for selecting emerging photocatalysts for reduction of oxidized pollutants. The preferred outcome is to achieve nitrate treatment under ambient conditions (e.g., pH) and without the need of adding an organic hole scavenger.The project focuses on nitrate, the most prevalent groundwater contaminant in the USA and throughout many other parts the world. Managing the nitrogen cycle is one of the National Academy of Engineering Grand Challenges. Nitrate limits the use of the groundwater for potable purposes, and is a major cause of eutrophication in surface waters. The project will provide societal benefits as well as benefits to individual students. The primary intent is to disseminate knowledge and credible data on issues related to nitrate in drinking water and potential strategies to treat the water. Towards this end the team plans to organize sessions at conferences and develop an open-access website related to nitrate occurrence, health risks and treatment. The research will educate PhD students in environmental engineering and serve as a thesis topic for MS students at a non PhD-degree granting institution. The project will serve as a theme for several capstone senior projects, as part of a project oriented learning curriculum. This project also will support Obama Scholars at ASU (first-time underrepresented undergraduate student), such as a female Hispanic sophomore Civil Engineering student who has been instrumental in obtaining preliminary data for this proposal. Student(s) working on this project will participate in an experience in Washington, DC for 2 weeks where they will learn how science becomes policy.

1132779WESTERHOFFNINTRATE（NO3-）是北美和全球最普遍的地下水污染物之一。 它对人类健康构成风险，并对自然氮周期产生很大影响。 硝酸盐受饮用水中的USEPA调节，因为它是高铁血红蛋白血症的已知原因，还​​是“蓝色婴儿”？综合征，可能是致癌物或内分泌破坏者。 硝酸盐是一种可溶性离子，很难通过传统的凝结或吸附过程去除。 氧化污染物的风险最好通过化学或生物学减少到无害形式（例如N2- NO3-）来减轻。 据报道，光催化的还原已有数十年了，但尚未从一种减少硝酸盐的工程方法中研究。 通过发现本田 - 富岛效应对光催化水分拆分（例如，将氢作为可再生燃料的产生）以及随后在半导体的金属加载方面的进步提出的研究发起的研究表明，可以添加近乎中性的pH值，而无需添加牺牲剂。 此外，现在似乎有可能降低水3-水可以产生无害的副产品（N2），而不是需要其他治疗的不良副产品（例如，氨）。 在过去的十年中，消毒的光解在饮用水行业中很普遍，由于其有效性，小尺寸的足迹，在没有废水的情况下运行的能力，从化学，物质科学和物理学领域进行翻译研究，因此，在材料科学和物理学领域进行了转化，因此在供应供应水上，因此可以使用水上的技术，因此，将基于光的占地面积，小尺寸的占地面积，在没有废水领域的转化研究的情况下，使用基于光的技术来继续发展。 PI的初步数据证明了光催化降低硝酸盐并产生气态-N副产品的可行性。 该项目的目的是探索和优化使用光催化剂作为用于治疗饮用水应用中硝酸盐的还原技术。 潜在的假设是硝酸盐可以使用金属负载的光催化剂在饮用水应用中转化为无害的水种。 主要的研究目标是：（1）了解不同类型的光催化剂的影响NO3-将NO3降低到N2的因素和机制； （2）将光催化剂应用于离子交换盐水和局部地下水中的NO3-降低； （3）研究光反应器操作（浆液和固定膜光催化剂反应器）的实际方面，包括催化剂衰老的作用？关于减少NO3和催化剂恢复的催化剂性能； （4）用于硝酸盐和其他氧胺还原的新型光催化剂，并开发了一个框架，用于选择新兴的光催化剂，以还原氧化污染物。 首选的结果是在环境条件下（例如pH）实现硝酸盐治疗，而无需添加有机孔清除剂。该项目集中于硝酸盐，这是美国最普遍的地下水污染物，在美国乃至世界许多其他地区。 管理氮周期是美国国家工程学院的巨大挑战之一。 硝酸盐将地下水用于饮用途目的限制了地下水，这是地表水中富营养化的主要原因。 该项目将为个人学生提供社会利益和福利。 主要目的是传播有关饮用水中与硝酸盐有关的问题的知识和可靠数据，以及治疗水的潜在策略。 为此，团队计划在会议上组织会议，并开发与硝酸盐发生，健康风险和治疗有关的开放访问网站。 这项研究将教育博士生关于环境工程的教育，并为非博士学位授予机构的MS学生提供论文主题。 该项目将作为以项目为导向的学习课程的一部分的几个Capstone高级项目的主题。该项目还将支持ASU的奥巴马学者（首次代表性不足的本科生），例如一名女性西班牙裔大二的土木工程专业学生，该学生在此提案中获取初步数据方面发挥了重要作用。 从事该项目的学生将参加华盛顿特区的经验2周，他们将学习科学如何成为政策。