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

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

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.