1. What is the role of nitrate/nitrite in trace organic contaminants degradation and transformation during UV-based advanced oxidation processes?
- Author
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Ao X, Zhang X, Sun W, Linden KG, Payne EM, Mao T, and Li Z
- Subjects
- Nitrites, Nitrates, Ultraviolet Rays, Nitrogen Dioxide, Hydrogen Peroxide, Organic Chemicals, Oxidation-Reduction, Water Pollutants, Chemical analysis, Water Purification methods
- Abstract
The effectiveness of UV-based advanced oxidation processes (UV-AOPs) in degrading trace organic contaminants (TrOCs) can be significantly influenced by the ubiquitous presence of nitrate (NO
3 - ) and nitrite (NO2 - ) in water and wastewater. Indeed, NO3 - /NO2 - can play multiple roles of NO3 - /NO2 - in UV-AOPs, leading to complexities and conflicting results observed in existing research. They can inhibit the degradation of TrOCs by scavenging reactive species and/or competitively absorbing UV light. Conversely, they can also enhance the elimination of TrOCs by generating additional •OH and reactive nitrogen species (RNS). Furthermore, the presence of NO3 - /NO2 - during UV-AOP treatment can affect the transformation pathways of TrOCs, potentially resulting in the nitration/nitrosation of TrOCs. The resulting nitro(so)-products are generally more toxic than the parent TrOCs and may become precursors of nitrogenous disinfection byproducts (N-DBPs) upon chlorination. Particularly, since the impact of NO3 - /NO2 - in UV-AOPs is largely due to the generation of RNS from NO3 - /NO2 - including NO•, NO2 •, and peroxynitrite (ONOO- /ONOOH), this review covers the generation, properties, and detection methods of these RNS. From kinetic, mechanistic, and toxicologic perspectives, future research needs are proposed to advance the understanding of how NO3 - /NO2 - can be exploited to improve the performance of UV-AOPs treating TrOCs. This critical review provides a comprehensive framework outlining the multifaceted impact of NO3 - /NO2 - in UV-AOPs, contributing insights for basic research and practical applications of UV-AOPs containing NO3 - /NO2 - ., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
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