skip to main content

This content will become publicly available on April 20, 2023

Title: Electrocatalytic generation of reactive species and implications in microbial inactivation
Controlling microbial proliferation in water systems, including wastewater, recreational water, and drinking water, is essential to societal health. Microbial inactivation through electrochemically generated reactive species (RS) mediated pathways provides an effective route toward this microbial control. Herein we provide an overview of recent progress toward electrocatalytic generation of RS and their application in water disinfection, with a focus on the selective production of RS, the microorganism interactions with RS (including both RS mechanisms of action and innate microorganism responses to RS), and practical implementation of electrochemically generated RS for microbial inactivation. The article is concluded with a perspective where the challenges and opportunities of RS‐based electrochemical disinfection of water are highlighted, along with possible future research directions.
Authors:
; ;
Award ID(s):
1848841
Publication Date:
NSF-PAR ID:
10320116
Journal Name:
Chinese journal of catalysis
Volume:
43
ISSN:
1872-2067
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Clean water free of bacteria is a precious resource in areas where no centralized water facilities are available. Conventional chlorine disinfection is limited by chemical transportation, storage, and the production of carcinogenic by-products. Here, a smartphone-powered disinfection system is developed for point-of-use (POU) bacterial inactivation. The integrated system uses the smartphone battery as a power source, and a customized on-the-go (OTG) hardware connected to the phone to realize the desired electrical output. Through a downloadable mobile application, the electrical output, either constant current (20–1000 µA) or voltage (0.7–2.1 V), can be configured easily through a user-friendly graphical interface on the screen.more »The disinfection device, a coaxial-electrode copper ionization cell (CECIC), inactivates bacteria by low levels of electrochemically generated copper with low energy consumption. The strategy of constant current control is applied in this study to solve the problem of uncontrollable copper release by previous constant voltage control. With the current control, a high inactivation efficiency ofE. coli(~6 logs) is achieved with a low level of effluent Cu (~200 µg L−1) in the water samples within a range of salt concentration (0.2–1 mmol L−1). The smartphone-based power workstation provides a versatile and accurate electrical output with a simple graphical user interface. The disinfection device is robust, highly efficient, and does not require complex equipment. As smartphones are pervasive in modern life, the smartphone-powered CECIC system could provide an alternative decentralized water disinfection approach like rural areas and outdoor activities.

    « less
  2. A rapid and sensitive method is described for measuring perchlorate (ClO 4 − ), chlorate (ClO 3 − ), chlorite (ClO 2 − ), bromate (BrO 3 − ), and iodate (IO 3 − ) ions in natural and treated waters using non-suppressed ion chromatography with electrospray ionization and tandem mass spectrometry (NS-IC-MS/MS). Major benefits of the NS-IC-MS/MS method include a short analysis time (12 minutes), low limits of quantification for BrO 3 − (0.10 μg L −1 ), ClO 4 − (0.06 μg L −1 ), ClO 3 − (0.80 μg L −1 ), and ClO 2 − (0.40more »μg L −1 ), and compatibility with conventional LC-MS/MS instrumentation. Chromatographic separations were generally performed under isocratic conditions with a Thermo Scientific Dionex AS16 column, using a mobile phase of 20% 1 M aqueous methylamine and 80% acetonitrile. The isocratic method can also be optimized for IO 3 − analysis by including a gradient from the isocratic mobile phase to 100% 1 M aqueous methylamine. Four common anions (Cl − , Br − , SO 4 2− , and HCO 3 − /CO 3 2− ), a natural organic matter isolate (Suwannee River NOM), and several real water samples were tested to examine influences of natural water constituents on oxyhalide detection. Only ClO 2 − quantification was significantly affected – by elevated chloride concentrations (>2 mM) and NOM. The method was successfully applied to quantify oxyhalides in natural waters, chlorinated tap water, and waters subjected to advanced oxidation by sunlight-driven photolysis of free available chlorine (sunlight/FAC). Sunlight/FAC treatment of NOM-free waters containing 200 μg L −1 Br − resulted in formation of up to 263 ± 35 μg L −1 and 764 ± 54 μg L −1 ClO 3 − , and up to 20.1 ± 1.0 μg L −1 and 33.8 ± 1.0 μg L −1 BrO 3 − (at pH 6 and 8, respectively). NOM strongly inhibited ClO 3 − and BrO 3 − formation, likely by scavenging reactive oxygen or halogen species. As prior work shows that the greatest benefits in applying the sunlight/FAC process for purposes of improving disinfection of chlorine-resistant microorganisms are realized in waters with lower DOC levels and higher pH, it may therefore be desirable to limit potential applications to waters containing moderate DOC concentrations ( e.g. , ∼1–2 mg C L −1 ), low Br − concentrations ( e.g. , <50 μg L −1 ), and circumneutral to moderately alkaline pH ( e.g. , pH 7–8) to strike a balance between maximizing microbial inactivation while minimizing formation of oxyhalides and other disinfection byproducts.« less
  3. Chlorine disinfection inevitably generates carcinogenic by-products. Alternative non-chlorine-based techniques in centralized treatment plants cannot produce residual antimicrobial power in water disinfection systems. Here, we propose locally enhanced electric field treatment (LEEFT) for chemical-free water disinfection in pipes. A tubular LEEFT device with coaxial electrodes is rationally developed for easy adaption to current water distribution systems as a segment of the pipelines. The center electrode is modified with perpendicularly grown nanowires, so that the electric field strength near the tips of the nanowires is significantly enhanced for pathogen inactivation. We have demonstrated >6-log inactivation of bacteria with 1 V, a smallmore »voltage that can be generated in situ by flowing water.« less
  4. The United Nations (UN) estimates that more than one billion people in this world do not have access to safe drinking water due to microbial hazards and it kills more than 7.6 million children every year via waterborne diseases. Driven by the need for the removal and inactivation of waterborne pathogens in drinking water, we report the chemical design and details of microscopic characterization of a bio-conjugated chitosan attached carbon nanotube based three dimensional (3D) nanoporous architecture, which has the capability for effective separation and complete disinfection of waterborne pathogens from environmental water samples. In the reported design, chitosan, amore »biodegradable antimicrobial polysaccharide with an architecture-forming ability has been used for the formation of 3D pores as channels for water passage, as well as to increase the permeability on the inner and outer architectures for killing Rotavirus and Shigella waterborne pathogens. On the other hand, due to their large surface area, CNTs have been wrapped by chitosan to enhance the adsorption capability of the architecture for the separation and removal of pathogens from water. The reported data show that the anti- Rotavirus VP7 antibody and LL-37 antimicrobial peptide conjugated chitosan–CNT architecture can be used for efficient separation, identification and 100% eradication of Rotavirus and Shigella waterborne pathogens from water samples of different sources. A detailed mechanism for the separation and inactivation of waterborne pathogens using the bio-conjugated chitosan based 3D architecture has been discussed using microscopic and spectroscopic studies. Reported experimental data demonstrate that the multifunctional bio-conjugated 3D architecture has good potential for use in waterborne pathogen separation and inactivation technology.« less
  5. This study proposes a novel disinfection process by sequential application of peracetic acid (PAA) and ultra-violet light (UV), on the basis of elucidation of disinfection mechanisms under UV/PAA. Results show that hydroxyl radicals, generated by UV-activated PAA, contribute to the enhanced inactivation of Escherichia coli under UV/PAA compared to PAA alone or UV alone. Furthermore, the location of hydroxyl radical generation is a critical factor. Unlike UV/H2O2, which generates hydroxyl radicals mainly in the bulk solution, the hydroxyl radicals under UV/PAA are produced close to or inside E. coli cells, due to PAA diffusion. Therefore, hydroxyl radicals exert significantly strongermore »disinfection power under UV/PAA than under UV/H2O2 conditions. Pre-exposing E. coli to PAA in the dark followed by application of UV (i.e., a PAA-UV/PAA process) promotes diffusion of PAA to the cells and achieves excellent disinfection efficiency while saving more than half of the energy cost associated with UV compared to simultaneous application of UV and PAA. The effectiveness of this new disinfection strategy has been demonstrated not only in lab water but also in wastewater matrices.« less