Investigation on the electrodes applied in the locally enhanced electric field treatment (LEEFT) for water disinfection

水消毒对保护公众健康是必不可少的。氯、氯胺、臭氧和过氧化氢等化学氧化剂在水处理中被广泛用作消毒剂，以灭活饮用水水源中的水媒病原体。不幸的是，这些化学氧化剂也会与有机污染物和溶解的有机物反应，产生各种消毒副产物，如三卤代甲烷和N-亚硝基二甲胺，它们的毒性会对人体健康造成不利影响。局部增强电场处理(Leeft)是一种很有前途的消毒工艺，可以在不使用化学物质的情况下灭活水中的病原体。在Leeft的水消毒过程中，利用具有两个平行板电极的装置来产生强大的电场，当水流经该装置时，该电场可以通过破坏微生物病原体的细胞膜来灭活它们。尽管实验室规模的Leeft设备已经证明了高的水消毒效率，但电极的耐用性仍然是一个关键的和尚未解决的挑战，将设备的寿命限制在几天之内。该项目的总体目标是提高左电极的耐用性和寿命，使其能够在水消毒中使用。为了推进这一目标，首席调查人员建议研究左电极的腐蚀过程和机理，目的是找出有效的解决方案，以提高其耐用性和寿命。这项研究的成功完成将通过产生新的基础知识和更耐用的电极材料来推动基于Leeft的水消毒系统的开发和实施，从而造福社会。将通过学生教育和培训，包括对佐治亚理工学院一名研究生的指导，为社会带来更多好处。局部增强电场处理(Leeft)是一种很有前途的物理消毒工艺，它利用两个平行平板电极的装置产生强大的电场，可以灭活水中的微生物病原体。目前的Leeft设备的电极通常使用纳米结构(例如纳米线)来功能化，以增强电场，同时降低实现病原体灭活的目标范围和速度所需的操作电压。该项目的目标是1)研究纳米线功能化LEET电极的腐蚀过程和机理，2)确定和评估提高电极耐久性的有效解决方案。为了推进这些目标，首席研究人员(PI)建议：(1)制备和表征一系列新的纳米线功能化LEET电极；(2)利用成像和分析工具相结合的方式，系统地研究这些电极在不同电化学和水力条件下的耐久性，以可视化和量化电极的侵蚀和转变，包括扫描电子显微镜(SEM)和能量色散光谱(EDS)、透射式电子显微镜(TEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)。为了找出提高电极耐用性的有效解决方案，PIS建议探索几种策略，包括1)使用较难溶于酸或与电极基材结合更强的前体材料制造LEET纳米线电极，以及2)在LEET纳米线电极上涂覆薄保护层。这项研究的成功完成有可能通过产生新的基础知识和更耐用的电极材料来促进下一代高性能Leeft水消毒系统的开发，从而产生革命性的影响。为了实施该项目的教育和外展活动，个人投资促进机构计划将这项研究的结果纳入佐治亚理工学院现有的环境工程课程模块。此外，PI计划利用佐治亚理工学院的GIFT(佐治亚教师实习生奖学金)计划为当地一名K-12教师提供研究培训。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Water disinfection is essential for the protection of public health. Chemical oxidants such as chlorine, chloramine, ozone, and hydrogen peroxide are widely utilized in water treatment as disinfectants to deactivate water-borne pathogens from drinking water sources. Unfortunately, these chemical oxidants can also react with organic contaminants and dissolved organic matter to generate various disinfection byproducts such as trihalomethanes and N-nitroso-dimethylamine which can adversely impact human health due to their toxicity. Locally enhanced electric field treatment (LEEFT) has emerged as a promising disinfection process that can deactivate water-borne pathogens without using chemicals. During water disinfection by LEEFT, a device with two parallel plate electrodes is utilized to generate a strong electric field that can deactivate microbial pathogens by disrupting their cell membranes as the water flows through the device. Although high water disinfection efficiencies have been demonstrated using lab scale LEEFT devices, electrode durability remains a critical and unresolved challenge limiting device lifespans to only a few days. The overarching goal of this project is to improve the durability and lifespan of LEEFT electrodes to enable their utilization in water disinfection. To advance this goal, the Principal Investigators propose to study the process and mechanisms of erosion of LEEFT electrodes with the aim of identifying effective solutions for improving their durability and lifespans. The successful completion of this research will benefit society through the generation of new fundamental knowledge and more durable electrodes materials to advance the development and implementation of LEEFT-based water disinfection systems. Additional benefits to society will be achieved through student education and training including the mentoring of a graduate student at Georgia Tech. Locally enhanced electric field treatment (LEEFT) has emerged as a promising physical disinfection process that utilizes a device with two parallel plate electrodes to generate a strong electric field that can deactivate water-borne microbial pathogens. The electrodes of current LEEFT devices are typically functionalized with nanostructures (e.g., nanowires) to enhance the electric field while reducing the operational voltage required to achieve the target extents and rates of pathogen deactivation. The goals of this project are to 1) investigate the process and mechanisms of erosion of nanowire-functionalized LEET electrodes and 2) identify and evaluate effective solutions for improving electrode durability. To advance these goals, the Principal Investigators (PIs) propose to (1) fabricate and characterize a series of new nanowire-functionalized LEET electrodes and (2) carry out a systematic investigation of the durability of these electrodes when there are exposed to different electrochemical and hydraulic conditions using a combination of imaging and analytic tools to visualize and quantify electrode erosion and transformations including scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). To identify effective solutions for improving electrode durability, the PIs propose to explore several strategies including 1) the fabrication of LEET nanowire electrodes using precursor materials that are less soluble in acids or bind more strongly to the electrode substrates and 2) the coating of LEET nanowire electrodes with thin protective layers. The successful completion of this research has the potential for transformative impact through the generation of new fundamental knowledge and more durable electrode materials to advance the development of next generation high-performance LEEFT systems for water disinfection. To implement the education and outreach activities of the project, the PIs plan to integrate the findings from this research into existing environmental engineering course modules at Georgia Tech. In addition, the PI plans to leverage the GIFT (Georgia Intern Fellowship for Teachers) program at Georgia Tech to provide research training to a local K-12 teacher.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.