Evaluation of a chloramine decomposition model incorporating general acid catalysis

Valentine, Richard L.; Jafvert, Chad T.; Leung, Solomon W.

doi:10.1016/0043-1354(88)90010-3

Cited by 27 publications

(28 citation statements)

References 5 publications

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“…The calculated gas and aqueous phase standard state enthalpies and free energies for Reactions 7,8,9,12, and 16 are given in Table 9. Reaction 7 is predicted to be exergonic in gas ( rxn G • = −59 to −73 kJ/mol) and PCM/CPCM aqueous phases (−9 kJ/mol), but the SMD solvation model suggests an endergonic reaction (+12 to 13 kJ/mol).…”

Section: Resultsmentioning

confidence: 99%

“…Although the kinetics of chloramination have been widely studied and mechanisms proposed therefrom, [5,[8][9][10][11][12][13][14] relatively little appears to be known about the thermodynamics of these important water treatment processes. Thus, in the current study we undertake the first high level theoretical thermodynamic investigation on the primary reactions during chloramination, as well as extend our studies to a number of other related reactions thought to be important for this process.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic properties of chloramine formation and related reactions during water treatment: A G4MP2, G4, and W1BD theoretical study

Rayne¹,

Forest

2014

Journal of Environmental Science and Health, Part A

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A high-level gas and aqueous phase theoretical thermodynamic study was conducted on the primary and related chemical reactions which occur during chloramination for water treatment using the G4MP2, G4, and W1BD composite methods with the SMD, PCM, and CPCM solvation models. The standard state (298.15 K, 1 atm or 1M) formation of mono-, di-, and tri-chloramines from their precursors via hypochlorous acid chlorination is substantially exothermic and exergonic in both the gas and aqueous phases. The excellent agreement between experimental and theoretical values for a range of structural and thermodynamic calculations on a suite of calibration compounds suggests that the G4MP2, G4, and W1BD calculations meet or exceed criteria for thermochemical accuracy. The temperature influence on the thermodynamics of chloramine formation is projected to be negligible regardless of phase between 0 and 100°C. Additional thermodynamic calculations were undertaken on associated chloramination reactions involving the disproportionation of monochloramine, the decomposition of di- and tri-chloramine, and the reactions of trichloramine with ammonia and dichloramine. The results from these investigations not only provide a better understanding of the reaction thermodynamics, they also allow for a more rigorous interpretation of proposed chloramination mechanisms.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermodynamic properties of chloramine formation and related reactions during water treatment: A G4MP2, G4, and W1BD theoretical study

Rayne¹,

Forest

2014

Journal of Environmental Science and Health, Part A

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“…In addition, direct and reverse reactions are elementary and each one follows a kinetics law of second order [24,35,41]. Beyond the theoretical value of the molar ratio 1.5/1, the formation of trichloramine takes place [33].…”

Section: Influence Of the Ratio Of Chlorine-ammoniamentioning

confidence: 99%

“…2 shows that the maximum rate of the monochloramine formation occurs at the pH M , where the product of HOCl and NH þ 4 is the highest; which is the midpoint of the both values of pka 8.4 [18], and so the monochloramine formation is rapidly accomplished in a few seconds and it is the predominant species in potable water pH including in 6.5-8.5. The hydrolysis of monochloramine is very slow and follows kinetics law of order one [35]: …”

Section: Monochloraminementioning

confidence: 99%

Modeling drinking water chlorination at the breakpoint: I. Derivation of breakpoint reactions

Driss¹,

Bouhelassa²

2014

Desalination and Water Treatment

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A B S T R A C TFrom a bibliographic synthesis on the reactions that can occur during breakpoint chlorination. We carry out the stability study of produced entities under the applied conditions in the potable water production, where the pH range 6.5-8.5, and the initial weight ratio Cl/N including in 10/1-15/1 at ambient temperature. The choice of dominant species and reactions that have been taken into account must be based on data of the thermodynamics and the kinetics governed by pH and temperature. Through this selection appears a large disagreement in results of researches between the rate expressions of the kinetics and observed and even with the empirical results, especially for reaction the monochloramine formation and for equilibrium the formation-hydrolysis of trichloramine. Then, the nature of identified intermediate and the observed rate of its formation reaction were not agree in different published works, as well the possibility of destruction of the free chlorine residual by this intermediate is not confirmed yet. Through this study, we obtain a representative selected group of reactions during breakpoint chlorination process, this identified group of reactions is compared with other models of breakpoint reactions proposed in the literature, where some differences appear.

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“…Previously research results had proposed that bulk decay was influenced by temperature, pH, organic levels, and inorganic ions (Duirk et al, 2005;Gang et al, 2003;Valentine et al, 1988;Vikesland et al, 2001). When nitrification occurs in drinking water systems during chloramination at fixed water temperature and pH, chloramines auto-decomposition, reaction with organics and nitrite contribute principally to the chloramines decay (Krishna and Sathasivan, 2010;Sathasivan et al, 2008).…”

Section: Buii( Chioramines Decay Modeimentioning

confidence: 99%

Monochloramine Decay for Two Chlorine to Ammonia Ratios in Bulk Water

Zhou

Zhang

Zeng

2013

Water Environment Research

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Within the context of the treatment of tap water as a research objective, a bulk model has been developed to describe chloramines decay for chlorine to ammonia ratios of 3:1 and 4:1. The model is based on studies of isolated individual reactions and also concerning the chloramines decay as a whole. The experimental results were used to estimate and verify the model for use in actual drinking water distribution systems under various chloramines conditions. The overall model formulation works reasonably well in describing chloramines decay in bulk water containing natural organic matter (NOM) and nitrite over a variety of reaction conditions. The data show that the auto-decomposition rate of chloramines is faster in the presence of NOM in bulk water for a chlorine to ammonia ratio (C1:N) of 3:1 versus 4:1. In contrast, the decay rate caused by nitrite is independent of the C1:N ratio. The decay rate increases with the NOM and nitrite concentrations and the temperature, but decreases with increasing pH. The effect of higher temperature on chloramines loss was more marked at the 3:1 C1:N ratio. Water Environ. Res., 85, 2194Res., 85, (2013.

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Evaluation of a chloramine decomposition model incorporating general acid catalysis

Cited by 27 publications

References 5 publications

Thermodynamic properties of chloramine formation and related reactions during water treatment: A G4MP2, G4, and W1BD theoretical study

Thermodynamic properties of chloramine formation and related reactions during water treatment: A G4MP2, G4, and W1BD theoretical study

Modeling drinking water chlorination at the breakpoint: I. Derivation of breakpoint reactions

Monochloramine Decay for Two Chlorine to Ammonia Ratios in Bulk Water

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