Formation of Silver and Copper "Nanopatches" in Ceramic Porous Media and Application for Point-of-Use Water Treatment

1438619(史密斯)。在美国和其他发达国家，高质量的饮用水通常通过集中式水处理和分配系统提供。在发展中国家，这些系统往往不可靠，无法满足处理过的水的需求，或者根本不存在。其结果是，30-40亿人得不到可靠的、高质量的供水。世界卫生组织表示，解决这一问题的一个可能的解决方案是分散水处理，这样人们就可以在家里喝水之前直接处理水。设计这样的“使用点”水处理技术是一个具有挑战性的问题，因为它们必须是低成本、技术有效、简单易用和社会接受的。在这项研究中，一种注入了纳米级银和/或铜补丁的多孔陶瓷片剂被提议用于使用点水处理。这种陶瓷片最适用于发展中国家的水处理，此外，它还解决了三重底线的三个要素：社会、经济和环境的可持续性。这种陶瓷片的制作将非常简单，成本也不高。使用时，将片剂放入10-20-L家用储水罐中，在那里它会逐渐将离子银和/或铜释放到水中。药片的设计是这样的，饮用水中的银/铜浓度将足以消毒水中病原体，同时不超过饮用水标准0.1毫克/L(银)或1.0毫克/L(铜)。在这项研究中，将使用不同的原料，包括两种粘土类型、不同粒度的锯末、不同浓度的硝酸银和硝酸铜，以及使用和不使用不同的还原和封盖剂来制备多片。在烧成过程中，离子银和铜将被还原为零价金属氧化态，在整个多孔陶瓷中形成“纳米片”。将使用透射电子显微镜来确定纳米颗粒的形态和尺寸分布，并使用汞测孔仪来评估陶瓷的孔径分布，以对片剂进行表征。通过对多孔介质扩散、对陶瓷孔壁的吸附和氧化动力学的模拟和基础实验，将确定这些传输过程的相对重要性，进而优化片剂设计。将对一系列水化学和浊度的病毒、细菌和原生动物病原体的消毒动力学进行量化。将进行短期(24小时)和长期(6个月)性能测试。将与文达大学(UNIVEN)和南非林波波省的三个农村社区一起对这项技术进行实地测试。在南非Ha-Mashamba以前建立的陶瓷过滤器厂工作的当地陶工将学习生产陶片。然后，这些平板电脑将在附近的两个南非农村社区进行现场测试。这些药片将作为独立的净水器进行评估，并与更传统的陶瓷滤水器结合使用。田野工作将利用最近授予的本科生研究经验项目的资源，该项目名为“水、社会和健康”。将在考虑经济、环境和社会因素的情况下对该技术进行生命周期分析。它在这些类别中的表现将与集中式水处理和分配系统以及其他使用点水处理技术进行比较。现有的使用点水处理技术要么具有相对较高的入门级价位(30美元)，要么在一次性使用后就会耗尽(Aquatabs、Pur袋子等)。相比之下，陶瓷平板净水器是一种潜在的颠覆性技术，可能会以5美元或6美元的价格出售，同时使用6个月，而不需要最终用户采取任何特殊行动。

1438619 (Smith). In the U.S. and other developed nations, high quality drinking water is typically provided through centralized water treatment and distributions systems. In the developing world, these systems are often unreliable, unable to meet the demand for treated water, or simply do not exist. As a result, 3-4 billion people do not receive reliable, high-quality water delivered to their households. The World Health Organization has indicated that one possible solution to this problem is to decentralize water treatment so that people treat their water right before they consume it in their homes. Designing such "point-of-use" water treatment technologies is a challenging problem, as they must be low cost, technologically effective, simple to use, and socially acceptable. For this study, a porous ceramic tablet infused with nanoscale patches of silver and/or copper is proposed for point-of-use water treatment. The ceramic tablet is most applicable to developing-world water treatment and further, it addresses the three elements of the Triple Bottom Line: social, economic, and environmental sustainability. The ceramic tablet will be simple and inexpensive to manufacture. For use, the tablet would be placed into a 10-20-L household water storage container, where it gradually would release ionic silver and/or copper into the water. The tablet design is such that silver/copper concentrations in the drinking water will be sufficient to disinfect waterborne pathogens while not exceeding the drinking water standards of 0.1 mg/L (silver) or 1.0 mg/L (copper). In this research, multiple tablets will be fabricated using different raw materials, including two clay types, sawdust with varying particle sizes, silver and copper nitrate at different concentrations, and with and without the use of different reducing and capping agents. During firing, ionic silver and copper will be reduced to zero-valent metallic oxidation states, forming "nanopatches" throughout the porous ceramic. The tablets will be characterized using transmission electron microscopy to determine nanopatch morphology and size distribution and using mercury porosimetry to evaluate ceramic pore-size distribution. Through simulation and fundamental experiments on porous media diffusion, sorption to ceramic pore walls, and oxidation kinetics, the relative importance of these transport processes will be determined and the tablet design will in turn be optimized. Disinfection kinetics will be quantified for viral, bacterial, and protozoan pathogens for a range of water chemistries and turbidities. Both short- (24-hr) and long-term (6-month) performance tests will be conducted. A field test of this technology will be performed in conjunction with the University of Venda (UNIVEN) and three rural communities located in Limpopo Province, South Africa. Local potters working at a previously established ceramic filter factory in Ha-Mashamba, S. Africa will be taught to produce ceramic tablets. These tablets will then be field tested in two nearby rural S. African communities. The tablets will be evaluated as stand-alone water purifiers, and in combination with more conventional ceramic water filters. Field work will leverage resources of a recently awarded Research Experiences for Undergraduates Site Program called "Water, Society, and Health." A life-cycle analysis of this technology will be performed with consideration of economic, environmental, and social factors. Its performance in these categories will be compared to centralized water-treatment and distribution systems and other point-of-use water treatment technologies. Existing point-of-use water treatment technologies have either a relatively high entry-level price point ( $30) or are depleted after a single use (Aquatabs, Pur sachets, etc.). By comparison, the ceramic tablet water purifier is a potentially disruptive technology that that likely could be sold for $5 or $6 while lasting for 6 months without any special action by the end user.