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Bromide Catalyzes the Transformation of Nitrite by Sulfate Radical Oxidation
https://orcid.org/0000-0002-9226-6601
https://orcid.org/0000-0001-6068-5820
Bromide (Br–) and nitrite (NO2 –) can be transformed to brominated and nitrophenolic byproducts, respectively, in sulfate radical (SO4 · –)-based oxidation processes, which has raised growing concern. In the present work, we examined the byproducts in the heat-activated persulfate oxidation system with the copresence of Br– and NO2 –, finding that Br– acted as a catalyst to accelerate the NO2 – transformation and nitrophenolic byproduct formation. Nitryl bromide (NO2Br) was the key intermediate in this process. It was generated by the reaction between NO2 – and free bromine in situ formed as the product of the oxidation of Br– by SO4 · –. As a strong nitrating agent, NO2Br reacted with natural organic matter directly, resulting in nitrophenolic byproducts. Alternatively, it reacted with excess NO2 – to form N2O4, which hydrolyzed to NO3 – ultimately. Both pathways were accompanied by releasing Br–. There was little Br– loss in the earlier reaction phase. Only after NO2 – was completely transformed, brominated byproduct formation occurred. Thus, the transformations of Br– and NO2 – are interweaved in SR-AOPs, which facilitates the formation of nitrophenolic byproducts but inhibits brominated byproducts. These new insights underscore the potential hazardous effects when SO4 · – oxidation is applied under realistic environmental conditions.
Br− catalyzes the transformation of NO2 − to NO3 − and nitrophenolic byproducts in sulfate radical oxidation processes.
Bromide Catalyzes the Transformation of Nitrite by Sulfate Radical Oxidation
https://orcid.org/0000-0002-9226-6601
https://orcid.org/0000-0001-6068-5820
Bromide (Br–) and nitrite (NO2 –) can be transformed to brominated and nitrophenolic byproducts, respectively, in sulfate radical (SO4 · –)-based oxidation processes, which has raised growing concern. In the present work, we examined the byproducts in the heat-activated persulfate oxidation system with the copresence of Br– and NO2 –, finding that Br– acted as a catalyst to accelerate the NO2 – transformation and nitrophenolic byproduct formation. Nitryl bromide (NO2Br) was the key intermediate in this process. It was generated by the reaction between NO2 – and free bromine in situ formed as the product of the oxidation of Br– by SO4 · –. As a strong nitrating agent, NO2Br reacted with natural organic matter directly, resulting in nitrophenolic byproducts. Alternatively, it reacted with excess NO2 – to form N2O4, which hydrolyzed to NO3 – ultimately. Both pathways were accompanied by releasing Br–. There was little Br– loss in the earlier reaction phase. Only after NO2 – was completely transformed, brominated byproduct formation occurred. Thus, the transformations of Br– and NO2 – are interweaved in SR-AOPs, which facilitates the formation of nitrophenolic byproducts but inhibits brominated byproducts. These new insights underscore the potential hazardous effects when SO4 · – oxidation is applied under realistic environmental conditions.
Br− catalyzes the transformation of NO2 − to NO3 − and nitrophenolic byproducts in sulfate radical oxidation processes.
Bromide Catalyzes the Transformation of Nitrite by Sulfate Radical Oxidation
https://orcid.org/0000-0002-9226-6601
https://orcid.org/0000-0001-6068-5820
Bromide (Br–) and nitrite (NO2 –) can be transformed to brominated and nitrophenolic byproducts, respectively, in sulfate radical (SO4 · –)-based oxidation processes, which has raised growing concern. In the present work, we examined the byproducts in the heat-activated persulfate oxidation system with the copresence of Br– and NO2 –, finding that Br– acted as a catalyst to accelerate the NO2 – transformation and nitrophenolic byproduct formation. Nitryl bromide (NO2Br) was the key intermediate in this process. It was generated by the reaction between NO2 – and free bromine in situ formed as the product of the oxidation of Br– by SO4 · –. As a strong nitrating agent, NO2Br reacted with natural organic matter directly, resulting in nitrophenolic byproducts. Alternatively, it reacted with excess NO2 – to form N2O4, which hydrolyzed to NO3 – ultimately. Both pathways were accompanied by releasing Br–. There was little Br– loss in the earlier reaction phase. Only after NO2 – was completely transformed, brominated byproduct formation occurred. Thus, the transformations of Br– and NO2 – are interweaved in SR-AOPs, which facilitates the formation of nitrophenolic byproducts but inhibits brominated byproducts. These new insights underscore the potential hazardous effects when SO4 · – oxidation is applied under realistic environmental conditions.
Br− catalyzes the transformation of NO2 − to NO3 − and nitrophenolic byproducts in sulfate radical oxidation processes.
Bromide Catalyzes the Transformation of Nitrite by Sulfate Radical Oxidation
Dong, Jiayue (author) / Yang, Peizeng (author) / Korshin, Gregory V. (author) / Lu, Junhe (author)
ACS ES&T Water ; 3 ; 3105-3112
2023-09-08
Article (Journal)
Electronic Resource
English
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