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Removing excessive nitrate (NO3−) from wastewater has increasingly become an important research topic in light of the growing concerns over the related environmental problems and health issues. In particular, catalytic/electrocatalytic approaches are attractive for NO3− removal, because NO3− from wastewater can be converted to N2 and released back to the atmosphere using renewable H2 or electricity, closing the loop of the global N cycle. However, achieving high product selectivity towards the desirable N2 has proven challenging in the direct NO3−-to-N2 reaction. In this presentation, we will report our finding on unique and ultra-high electrochemical NO3−-to-NO2−activity on an oxide-derived silver electrode (OD-Ag). Up to 98% selectivity and 95% faradaic efficiency of NO2− were observed and maintained under a wide potential window. Benefiting from overcoming the rate-determining barrier of NO3−-to-NO2−during nitrate reduction, further reduction of accumulated NO2− to NH4+ can be well regulated by the cathodic potential on OD-Ag to achieve a faradaic efficiency of 89%. These indicated the potential controllable pathway to the key nitrate reduction products (NO2−or NH4+) on OD-Ag. DFT computations provided insights into the unique NO2−selectivity on Ag electrodes compared with Cu, showing the critical role of a proton-assisted mechanism. Based on the ultra-high NO3−-to-NO2−activity on OD-Ag, we designed a novel electrocatalytic-catalytic combined process for denitrifying real-world NO3−-containing agricultural wastewater, leading to 95+% of NO3− conversion to N2 with minimal NOX gases. In addition to the wastewater treatment process to N2 and electrochemical synthesis of NH3, NO2− derived from electrocatalytic NO3− conversion can serve as a reactive platform for distributed production of various nitrogen products. Our new research progress along this direction will be briefly presented.more » « less
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Wastewater surveillance for infectious disease preparedness The University of Oklahoma Wastewater Based Epidemiology (OU WBE) team highlights successes from their three years of wastewater surveillance in Oklahoma & how this surveillance approach can be used as next-level monitoring for infectious disease preparedness. The OU WBE team, founded by Bradley Stevenson, Jason Vogel, and Katrin Gaardbo Kuhn in response to the COVID-19 pandemic in Summer 2020, has expanded to one of the most extensive wastewater monitoring networks in the world with a team that has included over 50 faculty, students and staff. In a paper published in 1942, Drs. James Trask and John Paul described a study to detect poliovirus in wastewater samples collected in New York and New Haven. They concluded, “It is likely that the periodic sampling of sewage for pathogenic viruses or bacteria may be a method of epidemiological value”. (1) Since then, wastewater surveillance has been used to detect sporadic outbreaks or clusters of various infectious pathogens, reaching new levels of routine utilization during the COVID-19 pandemic.(2)
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1029/2021GH000490
