ClO2 pre-oxidation impacts the formation and nitrogen origins of dichloroacetonitrile and dichloroacetamide during subsequent chloramination

Shao, Kai-Li; Ye, Zhao-Xi; Huang, Huang; Yang, Xin

doi:10.1016/j.watres.2020.116313

Cited by 14 publications

(12 citation statements)

References 49 publications

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“…Additionally, the formation of 15 N-DCAN increased as the Cl 2 /NH 3 molar ratios increased from 2.0 to 2.7 and then decreased as the ratios further increased to 4.0. 15 N-DCAN formation was greater than 14 N-DCAN formation and accounted for more than 68% of the total DCAN yield at Cl 2 /NH 3 molar ratios from 2.0 to 4.0. The identification of 15 N-DCAN highlighted a new pathway for the formation of DCAN precursors during breakpoint chlorination.…”

Section: ■ Materials and Methodsmentioning

confidence: 87%

“…DCAN was analyzed using m/z 74 as the quantification ion for unlabeled DCAN ( 14 N-DCAN) and m/z 75 for 15 N-labeled DCAN ( 15 N-DCAN). 14 A Bruker EMX-plus electron paramagnetic resonance (EPR) spectrometer was used to reveal the presence of • NO radicals. (DETC) 2 −Fe 2+ , serving as a spin-trapping agent for • NO radicals, was freshly prepared by mixing DETC and ferrous sulfate at a 2:1 M ratio.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Both organic nitrogen moieties in NOM and the inorganic nitrogen in NH 2 Cl can contribute to the nitrogen sources of DCAN. 13,14 However, the formation of N-nitrosodimethylamine (NDMA) has been reported to peak close to the breakpoint (at a Cl 2 /NH 3 molar ratio of about 1.8), at which there is no free chlorine or chloramine residual. 15 The results suggested the contribution of other reactive species (e.g., ONOO − and • OH) to NDMA formation.…”

Section: ■ Introductionmentioning

confidence: 99%

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Trichloramine and Hydroxyl Radical Contributions to Dichloroacetonitrile Formation Following Breakpoint Chlorination

Huang

Zheng

Jiao

et al. 2022

Environ. Sci. Technol.

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Breakpoint chlorination is applied to remove ammonia in water treatment. Trichloramine (NCl 3 ) and transient reactive species can be present, but how they affect the formation of nitrogenous disinfection byproducts is unknown. In this study, the dichloroacetonitrile (DCAN) formation mechanisms and pathways involved during breakpoint chlorination (i.e., free chlorine to ammonia molar ratio ≥2.0) were investigated. DCAN formation during breakpoint chlorination of natural organic matter (NOM) isolates was 14.3−20.3 μg/L, which was 2−10 times that in chlorination without ammonia at similar free chlorine residual conditions (2.1−2.9 mg/L as Cl 2 ). The probe tests and electron paramagnetic resonance spectra supported the presence of • OH, • NO, and NCl 3 besides free chlorine in breakpoint chlorination. 15 N-labeled ammonium-N tests indicated the incorporation of ammonium-N in DCAN formation though ammonia was eliminated during breakpoint chlorination. Aromatic non-nitrogenous moieties, such as phenols (i.e., none DCAN precursors in the free-chlorine-only system), became DCAN precursors during breakpoint chlorination. The reactions involved in reactive nitrogen species, such as • NO/ • NO 2 and NCl 3 , led to additional nitrogen sources in DCAN formation, accounting for 36−84% of total nitrogen sources in DCAN formation from NOM isolates and real water samples. Scavenging • OH by tert-butanol reduced DCAN formation by 40−56%, indicating an important role of • OH in transforming DCAN precursors. This study improves the understanding of breakpoint chlorination chemistry.

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Section: ■ Materials and Methodsmentioning

confidence: 87%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Trichloramine and Hydroxyl Radical Contributions to Dichloroacetonitrile Formation Following Breakpoint Chlorination

Huang

Zheng

Jiao

et al. 2022

Environ. Sci. Technol.

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“…Zhong [27] et al reported that the presence of ClO 2 reduced THMs the most, but not HAAs or HALs, in low-NH3-N wastewater. Shao [28] et al studied the effects of ClO 2 pre-oxidation on the formation of dichloroacetonitrile and dichloroacetamide during subsequent chloramination. It was found that ClO 2 oxidation had inverse effects on DCAN/cAm yields for hydroxybenzamides and tetracyclines.…”

Section: Introductionmentioning

confidence: 99%

Alleviation of Ultrafiltration Membrane Fouling by ClO2 Pre-Oxidation: Fouling Mechanism and Interface Characteristics

et al. 2022

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In order to alleviate membrane fouling and improve removal efficiency, a series of pretreatment technologies were applied to the ultrafiltration process. In this study, ClO2 was used as a pre-oxidation strategy for the ultrafiltration (UF) process. Humic acid (HA), sodium alginate (SA), and bovine serum albumin (BSA) were used as three typical organic model foulants, and the mixture of the three substances was used as a representation of simulated natural water. The dosages of ClO2 were 0.5, 1, 2, 4, and 8 mg/L, with 90 min pre-oxidation. The results showed that ClO2 pre-oxidation at low doses (1–2 mg/L) could alleviate the membrane flux decline caused by humus, polysaccharides, and simulated natural water, but had a limited alleviating effect on the irreversible resistance of the membrane. The interfacial free energy analysis showed that the interaction force between the membrane and the simulated natural water was also repulsive after the pre-oxidation, indicating that ClO2 pre-oxidation was an effective way to alleviate cake layer fouling by reducing the interaction between the foulant and the membrane. In addition, ClO2 oxidation activated the hidden functional groups in the raw water, resulting in an increase in the fluorescence value of humic analogs, but had a good removal effect on the fluorescence intensity of BSA. Furthermore, the membrane fouling fitting model showed that ClO2, at a low dose (1 mg/L), could change the mechanism of membrane fouling induced by simulated natural water from standard blocking and cake layer blocking to critical blocking. Overall, ClO2 pre-oxidation was an efficient pretreatment strategy for UF membrane fouling alleviation, especially for the fouling control of HA and SA at low dosages.

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“…The characteristics of SACs (such as the coordination environment of metal atoms, the adsorption interaction with reactants and intermediates, and the charge interaction between metals and carriers) determine their performance in environmental applications. By matching the actual needs of environmental remediation and the advantages of sacs based on the above-mentioned basic catalytic mechanism, potential environmental applications include Fenton-like reaction [ 55 , 61 , 62 ], electrocatalytic water treatment [ 56 , 63 , 64 ], dehalogenation [ 57 , 65 ], nitride reduction [ 66 , 67 ], photocatalytic treatment [ 58 , 68 , 69 ], removal of oxygen-containing acid ions [ 70 , 71 ], degradation of volatile organic compounds (VOCs) [ 72 , 73 ], etc.…”

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confidence: 99%

Applications of Single Atom Catalysts for Environmental Management

Zhang

Chen

et al. 2022

IJERPH

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ClO2 pre-oxidation impacts the formation and nitrogen origins of dichloroacetonitrile and dichloroacetamide during subsequent chloramination

Cited by 14 publications

References 49 publications

Trichloramine and Hydroxyl Radical Contributions to Dichloroacetonitrile Formation Following Breakpoint Chlorination

Trichloramine and Hydroxyl Radical Contributions to Dichloroacetonitrile Formation Following Breakpoint Chlorination

Alleviation of Ultrafiltration Membrane Fouling by ClO2 Pre-Oxidation: Fouling Mechanism and Interface Characteristics

Applications of Single Atom Catalysts for Environmental Management

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