Mechanisms of trichloramine removal with activated carbon: Stoichiometric analysis with isotopically labeled trichloramine and theoretical analysis with a diffusion-reaction model

Sakuma, Miki; Matsushita, Taku; Matsui, Yoshihiko; Aki, Tomoko; Isaka, Masahito; Shirasaki, Nobutaka

doi:10.1016/j.watres.2014.10.051

Cited by 9 publications

(16 citation statements)

References 29 publications

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“…In the gas phase, we detected 15 N2 in an amount equivalent to 0.54 μg of 15 N that was present in trichloramine in the liquid phase before SPAC treatment. This observation suggests that trichloramine was transformed to N2 gas by reductive reactions mediated by functional groups on the surface of the SPAC particles (Sakuma et al 2015). The other organic nitrogens were most likely not transformed into N2 gas but rather were adsorbed onto the carbon particles.…”

Section: Pac Treatment Of the Chlorinated Phenylalanine-containing Somentioning

confidence: 98%

“…To determine the mechanism by which PAC removed the off-flavor of the chlorinated phenylalaninecontaining solution, we treated a chlorinated 15 N-labeled-phenylalanine-containing solution with SPAC by using a procedure similar to that described by Sakuma et al (2015) (see SI). The nitrogen mass balances before and after SPAC treatment were determined by measuring the concentrations of chloramines, PAN, and BA in the liquid phase and the concentration of 15 N2 in the gas phase (see SI).…”

Section: Estimating the Contributions Of Commercially Unavailable Tpsmentioning

confidence: 99%

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Use of gas chromatography–mass spectrometry–olfactometry and a conventional flask test to identify off-flavor compounds generated from phenylalanine during chlorination of drinking water

et al. 2017

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Off-flavor in drinking water can be caused by transformation products (TPs) generated from organic compounds, such as amino acids, present during chlorination. However, the contributions of many of these TPs to overall off-flavor have not been quantified, mainly because the lack of appropriate chemical standards prevents sensory evaluation by means of a conventional flask test. In the present study, we used gas chromatography-mass spectrometry-olfactometry (GC-MS-O) to identify compounds responsible for the off-flavor generated by chlorination of an aqueous solution of the amino acid phenylalanine, and we propose a sensory evaluation procedure for quantification of the contributions of the identified TPs to the overall off-flavor, regardless of the availability of chemical standards of the TPs. GC-MS-O revealed that two TPs, N-chlorophenylacetaldimine and 2-chloro-2-phenylacetaldehyde, for which chemical standards are not commercially available, were the main components responsible for the off-flavor of the chlorinated solution. By using a sensory evaluation procedure involving a combination of GC-MS-O and a conventional flask test, we quantified the contributions of TPs to the overall off-flavor of the chlorinated solution. Approximately 60% of the off-flavor was attributable to free chlorine (13%), 2-chloro-2-phenylacetaldehyde (13%), trichloramine (12%) phenylacetaldehyde (11%) phenylacetonitrile (8%), and N-chlorophenylacetaldimine (2%). Treatment with powdered activated carbon (PAC) removed the off-flavor. Experiments with chlorination of N-labeled phenylalanine suggested that PAC reductively decomposed trichloramine into N gas and adsorbed all of the other identified TPs. Superfine PAC (median diameter, 0.7 μm) removed the off-flavor more rapidly than normal-size PAC (median diameter, 8.0 μm).

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Section: Pac Treatment Of the Chlorinated Phenylalanine-containing Somentioning

confidence: 98%

Section: Estimating the Contributions Of Commercially Unavailable Tpsmentioning

confidence: 99%

Use of gas chromatography–mass spectrometry–olfactometry and a conventional flask test to identify off-flavor compounds generated from phenylalanine during chlorination of drinking water

et al. 2017

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“…GAC filtration has further been known to remove mono-, di-and trichloramine by a chemical reaction at the carbon surface (Bauer and Snoeyink, 1973;Scaramelli and Digiano, 1977;Kochany and Lipczynska-Kochany, 2008;Sakuma et al, 2015).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

N2 yields from monochloramine conversion by granular activated carbons are decisive for effective swimming pool water treatment

2019

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Inorganic chloramines (mono-, di-and trichloramine) are formed in swimming pool water from the unintended reaction of free chlorine with ammonia that is introduced by bathers. Monochloramine is of particular interest as it is known to react further in pool water forming harmful DBPs, such carcinogenic N-nitrosodimethylamine (NDMA). During pool water treatment with granular activated carbon (GAC) filters, monochloramine is transformed by chemical reactions on the carbon surface to N 2 and ammonia. As ammonia is led back into the pool where it is chlorinated again under the renewed formation of inorganic chloramines, it is recommended to use GACs with a high N 2 yield for monochloramine transformation in pool water treatment.In this study, yields of N 2 and ammonia from monochloramine conversion by commercially available GACs were determined using a fixed-bed reactor system under conditions that are typical for swimming pool water treatment. The N 2 yields remained constant with on-going exposure of the GAC to monochloramine and ranged from 0.5% to 21.3%, depending on the type of GAC used. Correlation analyses were conducted to identify carbon properties that can determine the N 2 yield for monochloramine conversion, such as the amount of oxygen groups, the elemental composition and the trace metal content. It was found that the N 2 yield significantly correlates with the copper content of the tested carbons.Model calculations combining pool hydraulics with formation/abatement of inorganic chloramines and NDMA as well as chloramine transformations in GAC filters showed that the concentration of inorganic chloramines and carcinogenic NDMA can be

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“…Among the available technologies, activated carbon is an efficient and low-cost ($2.9-9.0/kg) material to remove the free chlorine from drinking water, due to its unique physical and chemical properties, such as large surface area, excellent porosity and safeness (McCreary & Snoeylnk 1981;Sakuma et al 2015;Rasheed et al 2016). The chlorine in water is transported into the pores of the activated carbon by diffusion and physical adsorption.…”

Section: Introductionmentioning

confidence: 99%

“…The dechlorination rate is critical to evaluate the performance of the activated carbon, particularly for activated carbon filter manufacturers. Although the kinetic reaction by activated carbon for chlorimines removal was intensively studied (Sakuma et al 2015;Matsushita et al 2017;Skibinski et al 2018), the direct kinetic performance of free chlorine removal by activated carbon was not well understood. Since the free chlorine acts as a precursor to form the chlorinated DBPs, it is of great importance to study the free chlorine removal by activated carbon.…”

Section: Introductionmentioning

confidence: 99%

Chemical kinetics and particle size effects of activated carbon for free chlorine removal from drinking water

Meng¹,

Li²,

Zhang³

et al. 2018

Water Practice and Technology

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Activated carbon is an economic material to grab free chlorine in drinking water to reduce potential health risks. In this research, chemical kinetic reaction of the activated carbon for free chlorine removal was studied, which exhibited the first order kinetic reaction performance. A relationship between the rate of chlorinated water flowing through the activated carbon, and the free chlorine (ClO−) concentrations before and after the reduction by activated carbon was obtained. The logarithm of the free chlorine concentration (lnC) was linearly related to the reciprocal of the volume flow rate (1/v). The slope was dependant on the kinetic constant of the activated carbon dechlorination reaction. This research is beneficial for the scientists and engineers to study the mechanism of the chemical kinetic reaction of the free chlorine removal by activated carbon and design activated carbon-loaded water purification reactors.

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Mechanisms of trichloramine removal with activated carbon: Stoichiometric analysis with isotopically labeled trichloramine and theoretical analysis with a diffusion-reaction model

Cited by 9 publications

References 29 publications

Use of gas chromatography–mass spectrometry–olfactometry and a conventional flask test to identify off-flavor compounds generated from phenylalanine during chlorination of drinking water

Use of gas chromatography–mass spectrometry–olfactometry and a conventional flask test to identify off-flavor compounds generated from phenylalanine during chlorination of drinking water

N2 yields from monochloramine conversion by granular activated carbons are decisive for effective swimming pool water treatment

Chemical kinetics and particle size effects of activated carbon for free chlorine removal from drinking water

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