Temperature dependence of hydroxyl radical reactions with chloramine species in aqueous solution

Gleason, Jamie M.; McKay, Garrett; Ishida, Kenneth P.; Mezyk, Stephen P.

doi:10.1016/j.chemosphere.2017.08.053

Cited by 22 publications

(19 citation statements)

References 52 publications

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“…Because of the complexity of the current reaction scheme, the mechanistic determination of R7 and R8 is beyond the scope of the current research and is an avenue of future research. Potential cross-interactions remain to be investigated between the chloramine species and known decomposition products of ONOOH/ONOO – , including hydrogen peroxide and hydroxyl radical. , In addition, deviations between the measured NO 2 – and NO 3 – formation and UF + RNS model simulated values (see Table S13 in Supporting Information S2.13) indicate the need for kinetic N 2 , NO 2 – , and NO 3 – data to validate and/or revise the Kirsch et al ONOOH/ONOO – decomposition model for drinking water conditions and temperatures. Finally, the UF + RNS model overpredicted the N 2 O data at pH 10 (Figure d) but underpredicted N 2 O at pH 7 to 9 (Figure a–c), with the corresponding WRSS and AWRSS shown in Table S10, illustrating the need to measure N 2 , NO 2 – , and NO 3 – kinetically in future work to facilitate further advancement of the UF + RNS model.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Potential cross-interactions remain to be investigated between the chloramine species and known decomposition products of ONOOH/ONOO − , including hydrogen peroxide and hydroxyl radical. 44,45 In addition, deviations between the measured NO 2 − and NO 3 − formation and UF + RNS model simulated values (see Table S13 in Supporting Information S2.13) indicate the need for kinetic N 2 , NO 2 − , and NO 3 − data to validate and/or revise the Kirsch et al 17 Mechanistic Considerations. This study presented multiple lines of evidence to demonstrate that NHCl 2 hydrolysis resulted in HNO formation (Scheme 1, U7), the so-called unidentified reactive intermediate (I) in the UF model.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

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Updated Reaction Pathway for Dichloramine Decomposition: Formation of Reactive Nitrogen Species and N-Nitrosodimethylamine

Wahman

Fairey

2021

Environ. Sci. Technol.

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The N-nitrosodimethylamine (NDMA) formation pathway in chloraminated drinking water remains unresolved. In pH 7–10 waters amended with 10 μM total dimethylamine and 800 μeq Cl2·L–1 dichloramine (NHCl2), NDMA, nitrous oxide (N2O), dissolved oxygen (DO), NHCl2, and monochloramine (NH2Cl) were kinetically quantified. NHCl2, N2O, and DO profiles indicated that reactive nitrogen species (RNS) formed during NHCl2 decomposition, including nitroxyl/nitroxyl anion (HNO/NO–) and peroxynitrous acid/peroxynitrite anion (ONOOH/ONOO–). Experiments with uric acid (a ONOOH/ONOO– scavenger) implicated ONOOH/ONOO– as a central node for NDMA formation, which were further supported by the concomitant N-nitrodimethylamine formation. A kinetic model accurately simulated NHCl2, NH2Cl, NDMA, and DO concentrations and included (1) the unified model of chloramine chemistry revised with HNO as a direct product of NHCl2 hydrolysis; (2) HNO/NO– then reacting with (i) HNO to form N2O, (ii) DO to form ONOOH/ONOO–, or (iii) NHCl2 or NH2Cl to form nitrogen gas; and (3) NDMA formation via ONOOH/ONOO– or their decomposition products reacting with (i) dimethylamine (DMA) and/or (ii) chlorinated unsymmetrical dimethylhydrazine (UDMH-Cl), the product of NHCl2 and DMA. Overall, updated NHCl2 decomposition pathways are proposed, yielding (1) RNS via and (2) NDMA via .

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Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Updated Reaction Pathway for Dichloramine Decomposition: Formation of Reactive Nitrogen Species and N-Nitrosodimethylamine

Wahman

Fairey

2021

Environ. Sci. Technol.

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“…In addition, the coexistence of chloride with NH 2 Cl also transformed SO 4 •– and Cl • to Cl 2 •– (reactions 2 and 3). HO • reacts with NH 2 Cl with a rate constant of 5.1 × 10 8 M –1 s –1 , and the second-order rate constant between SO 4 •– and NH 2 Cl of 2.4 × 10 7 M –1 s –1 was measured by laser flash photolysis (Text S4). For instance, up to 68% of HO • and 7% of SO 4 •– were scavenged by 4 mM NH 2 Cl (Texts S5.1 and S5.2 and Tables S3–S4).…”

Section: Resultsmentioning

confidence: 99%

“…•− and Cl • to Cl 2 •− (reactions 2 and 3). HO • reacts with NH 2 Cl with a rate constant of 5.1 × 10 8 M −1 s −1 , 44 and the second-order rate constant between SO 4…”

Section: •−mentioning

confidence: 99%

UV Photolysis of Chloramine and Persulfate for 1,4-Dioxane Removal in Reverse-Osmosis Permeate for Potable Water Reuse

Patton

Gleason

et al. 2018

Environ. Sci. Technol.

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116

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A sequential combination of membrane treatment and UV-based advanced oxidation processes (UV/AOP) has become the industry standard for potable water reuse. Chloramines are used as membrane antifouling agents and therefore carried over into the UV/AOP. In addition, persulfate (SO) is an emerging oxidant that can be added into a UV/AOP, thus creating radicals generated from both chloramines and persulfate for water treatment. This study investigated the simultaneous photolysis of SO and monochloramine (NHCl) on the removal of 1,4-dioxane (1,4-D) for potable-water reuse. The dual oxidant effects of NHCl and SO on 1,4-D degradation were examined at various levels of oxidant dosage, chloride, and solution pH. Results showed that a NHCl-to-SO molar ratio of 0.1 was optimal, beyond which the scavenging by NHCl of HO, SO, and Cl radicals decreased the 1,4-D degradation rate. At the optimal ratio, the degradation rate of 1,4-D increased linearly with the total oxidant dose up to 6 mM. The combined photolysis of NHCl and SO was sensitive to the solution pH due to a disproportionation of NHCl at pH lower than 6 into less-photoreactive dichloramine (NHCl) and radical scavenging by NH. The presence of chloride transformed HO and SO to Cl that is less-reactive with 1,4-D, while the presence of dissolved O promoted gaseous nitrogen production. Results from this study suggest that the presence of chloramines can be beneficial to persulfate photolysis in the removal of 1,4-D; however, the treatment efficiency depends on a careful control of an optimal NHCl dosage and a minimal chloride residue.

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“…At higher reaction times, the active hydroxyl production increases. The reaction performance improved when ample time for the oxidation process and free radical's attack on Ampicillin molecules were provided [24].…”

Section: Discussionmentioning

confidence: 99%

Advanced Oxidation Process Efficiently Removes Ampicillin from Aqueous Solutions

Shokri

Yengejeh

Babaei

et al. 2020

IJT

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Background: Antibiotics are considered important and integral parts of modern life, and are widely used for treating human and animal illnesses, in medicine and veterinary medicine. However, they can cause environmental pollution and may lead to increased bacterial resistance even at low concentrations. Methods: In this study, Ampicillin degradation from β-lactam antibiotic family was studied, using a surface methodology consisting of ultraviolet radiation (254 nm) and H2O2 oxidation process in an 8-watt Pyrex reactor. The variables used included the reaction time (30-60 min), Ampicillin concentration (5-25 mg/l), H2O2 concentration (5-25 mg/l), and pH range of 3-9 at three alpha levels of -1, 0 and +1. Results: The data were analyzed by the analysis of variance test (ANOVA), while the validity was evaluated using regression coefficients. The optimum condition for Ampicillin degradation followed a linear model, at a 60-min. reaction time and pH 3, the Ampicillin (5mg/l) and hydrogen peroxide (25mg/l) provided the maximum antibiotic removal efficiency (82%). Conclusions: The results suggest a positive and significant effect for the antibiotic concentration and a negative effect for the pH. The Ampicillin concentration with a coefficient of 8.91 had the highest impact on the efficiency of the removal process. Therefore, antibiotic pollution in the environment can be reduced through the UV-H2O2 process, so as to protect human health from the associated hazards.

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Temperature dependence of hydroxyl radical reactions with chloramine species in aqueous solution

Cited by 22 publications

References 52 publications

Updated Reaction Pathway for Dichloramine Decomposition: Formation of Reactive Nitrogen Species and N-Nitrosodimethylamine

Updated Reaction Pathway for Dichloramine Decomposition: Formation of Reactive Nitrogen Species and N-Nitrosodimethylamine

UV Photolysis of Chloramine and Persulfate for 1,4-Dioxane Removal in Reverse-Osmosis Permeate for Potable Water Reuse

Advanced Oxidation Process Efficiently Removes Ampicillin from Aqueous Solutions

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