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Influence of Nitrite on Ultraviolet-Activated Peroxydisulfate Degradation of 2,4-Dichlorophenol
https://orcid.org/0000-0001-6068-5820
https://orcid.org/0000-0003-0993-9068
Ultraviolet-activated peroxydisulfate (UV/PDS) oxidation has been considered as a promising technology for removing organic pollutants in wastewater. In this study, we investigated the abatement of 2,4-dichlorophenol (DCP) by UV/PDS, finding that the degradation can be attributed to both direct photolysis and sulfate radical (SO4 •–) oxidation. Intriguingly, the presence of trace levels of nitrite (NO2 –) increased the degradation rate and dramatically changed the degradation pathways. We propose that an in situ-generated reactive species, nitryl chloride (ClNO2), was responsible for this effect. UV irradiation played a critical role in the generation of ClNO2 because direct photolysis caused dechlorination of DCP. The released chloride (Cl–) was further oxidized by SO4 •– to a chlorine radical (Cl•). At the same time, NO2 – was oxidized by SO4 •– to nitrogen dioxide radicals (NO2 •). Combination of Cl• and NO2 • gave rise to ClNO2. This mechanism was not found in the heat-activated PDS system since SO4 •– oxidation resulted in little dechlorination. As a strong nitrating agent, ClNO2 reacted rapidly with DCP to form 2,4-dichloro-6-dinitrophenol (DCNP) as the primary transformation product. The yield reached 60.1% in 12 min in the presence of 50 μM NO2 –. The bioluminescence inhibition assay revealed that DCNP is more toxic than DCP. This contribution indicates that the activation approach can significantly influence the degradation behavior of halogenated pollutants in PDS oxidation systems.
Influence of Nitrite on Ultraviolet-Activated Peroxydisulfate Degradation of 2,4-Dichlorophenol
https://orcid.org/0000-0001-6068-5820
https://orcid.org/0000-0003-0993-9068
Ultraviolet-activated peroxydisulfate (UV/PDS) oxidation has been considered as a promising technology for removing organic pollutants in wastewater. In this study, we investigated the abatement of 2,4-dichlorophenol (DCP) by UV/PDS, finding that the degradation can be attributed to both direct photolysis and sulfate radical (SO4 •–) oxidation. Intriguingly, the presence of trace levels of nitrite (NO2 –) increased the degradation rate and dramatically changed the degradation pathways. We propose that an in situ-generated reactive species, nitryl chloride (ClNO2), was responsible for this effect. UV irradiation played a critical role in the generation of ClNO2 because direct photolysis caused dechlorination of DCP. The released chloride (Cl–) was further oxidized by SO4 •– to a chlorine radical (Cl•). At the same time, NO2 – was oxidized by SO4 •– to nitrogen dioxide radicals (NO2 •). Combination of Cl• and NO2 • gave rise to ClNO2. This mechanism was not found in the heat-activated PDS system since SO4 •– oxidation resulted in little dechlorination. As a strong nitrating agent, ClNO2 reacted rapidly with DCP to form 2,4-dichloro-6-dinitrophenol (DCNP) as the primary transformation product. The yield reached 60.1% in 12 min in the presence of 50 μM NO2 –. The bioluminescence inhibition assay revealed that DCNP is more toxic than DCP. This contribution indicates that the activation approach can significantly influence the degradation behavior of halogenated pollutants in PDS oxidation systems.
Influence of Nitrite on Ultraviolet-Activated Peroxydisulfate Degradation of 2,4-Dichlorophenol
https://orcid.org/0000-0001-6068-5820
https://orcid.org/0000-0003-0993-9068
Ultraviolet-activated peroxydisulfate (UV/PDS) oxidation has been considered as a promising technology for removing organic pollutants in wastewater. In this study, we investigated the abatement of 2,4-dichlorophenol (DCP) by UV/PDS, finding that the degradation can be attributed to both direct photolysis and sulfate radical (SO4 •–) oxidation. Intriguingly, the presence of trace levels of nitrite (NO2 –) increased the degradation rate and dramatically changed the degradation pathways. We propose that an in situ-generated reactive species, nitryl chloride (ClNO2), was responsible for this effect. UV irradiation played a critical role in the generation of ClNO2 because direct photolysis caused dechlorination of DCP. The released chloride (Cl–) was further oxidized by SO4 •– to a chlorine radical (Cl•). At the same time, NO2 – was oxidized by SO4 •– to nitrogen dioxide radicals (NO2 •). Combination of Cl• and NO2 • gave rise to ClNO2. This mechanism was not found in the heat-activated PDS system since SO4 •– oxidation resulted in little dechlorination. As a strong nitrating agent, ClNO2 reacted rapidly with DCP to form 2,4-dichloro-6-dinitrophenol (DCNP) as the primary transformation product. The yield reached 60.1% in 12 min in the presence of 50 μM NO2 –. The bioluminescence inhibition assay revealed that DCNP is more toxic than DCP. This contribution indicates that the activation approach can significantly influence the degradation behavior of halogenated pollutants in PDS oxidation systems.
Influence of Nitrite on Ultraviolet-Activated Peroxydisulfate Degradation of 2,4-Dichlorophenol
Zhao, Xulei (Autor:in) / Gui, Jingjing (Autor:in) / Yang, Peizeng (Autor:in) / Kong, Deyang (Autor:in) / Lu, Junhe (Autor:in) / Chovelon, Jean-Marc (Autor:in) / Ji, Yuefei (Autor:in)
ACS ES&T Engineering ; 3 ; 2008-2015
10.11.2023
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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