Kinetics of the chlorination of biphenyl under conditions of waste treatment processes

Snider, Eric H.; Alley, F. C.

doi:10.1021/es60158a016

Cited by 19 publications

(11 citation statements)

References 15 publications

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“…where Formation of Br 2 O as an active brominating agent can account for the near second-order dependence of DM bromination rates on [HOBr] T observed at pH ∼8.6. Analogous reports in the chlorination literature 9,18,19,57,58 have attributed a second-order dependence of chlorination rates on [FAC] o to reactions with Cl 2 O. Indeed, Cl 2 O was found to be nearly 8 million times more inherently reactive than HOCl in reactions with DM.…”

Section: Reaction Order In [supporting

confidence: 54%

Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr Toward Dimethenamid in Solutions of Bromide + Aqueous Free Chlorine

Sivey¹,

Arey²,

Tentscher³

et al. 2013

Environ. Sci. Technol.

101

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HOBr, formed via oxidation of bromide by free available chlorine (FAC), is frequently assumed to be the sole species responsible for generating brominated disinfection byproducts (DBPs). Our studies reveal that BrCl, Br(2), BrOCl, and Br(2)O can also serve as brominating agents of the herbicide dimethenamid in solutions of bromide to which FAC was added. Conditions affecting bromine speciation (pH, total free bromine concentration ([HOBr](T)), [Cl(-)], and [FAC](o)) were systematically varied, and rates of dimethenamid bromination were measured. Reaction orders in [HOBr](T) ranged from 1.09 (±0.17) to 1.67 (±0.16), reaching a maximum near the pK(a) of HOBr. This complex dependence on [HOBr](T) implicates Br(2)O as an active brominating agent. That bromination rates increased with increasing [Cl(-)], [FAC](o) (at constant [HOBr](T)), and excess bromide (where [Br(-)](o)>[FAC](o)) implicate BrCl, BrOCl, and Br(2), respectively, as brominating agents. As equilibrium constants for the formation of Br(2)O and BrOCl (aq) have not been previously reported, we have calculated these values (and their gas-phase analogues) using benchmark-quality quantum chemical methods [CCSD(T) up to CCSDTQ calculations plus solvation effects]. The results allow us to compute bromine speciation and hence second-order rate constants. Intrinsic brominating reactivity increased in the order: HOBr ≪ Br(2)O < BrOCl ≈ Br(2) < BrCl. Our results indicate that species other than HOBr can influence bromination rates under conditions typical of drinking water and wastewater chlorination.

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Section: Reaction Order In [supporting

confidence: 54%

Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr Toward Dimethenamid in Solutions of Bromide + Aqueous Free Chlorine

Sivey¹,

Arey²,

Tentscher³

et al. 2013

Environ. Sci. Technol.

101

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“…The order of MA chlorination in [HOCl] is approximately 1.9 at pH 6.6, 7.0, and 7.5 (SI Figure S6). Reaction orders in [HOCl] greater than 1.0 can be explained by the presence of Cl 2 O as an active chlorinating agent, − , recalling that [Cl 2 O] is proportional to [HOCl] 2 . As the effects of added chloride are minor at pH ≥ 7 (Figure ), the presence of chloride in FAC stock solutions is unlikely to account for the approximately second-order dependence of MA chlorination rates on [HOCl] at pH ≥ 7.…”

Section: Resultsmentioning

confidence: 99%

“…Limited kinetic data indicate that Cl 2 and Cl 2 O can, in fact, be more potent chlorinating agents of organic compounds than HOCl. − Nonetheless, very little data exist to indicate which organic structures are particularly susceptible to chlorination by Cl 2 or Cl 2 O under conditions typical of drinking water (DW) and wastewater (WW) chlorination. Previous work in our laboratory indicated that Cl 2 and Cl 2 O can strongly influence chlorination rates of the herbicide dimethenamid (DM) in solutions of FAC.…”

Section: Introductionmentioning

confidence: 99%

Assessing the Reactivity of Free Chlorine Constituents Cl₂, Cl₂O, and HOCl Toward Aromatic Ethers

Sivey

Roberts

2012

Environ. Sci. Technol.

105

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Cl(2) and Cl(2)O are highly reactive electrophiles capable of influencing rates of disinfection byproduct (DBP) precursor chlorination in solutions of free available chlorine (FAC). The current work examines how organic compound structure influences susceptibility toward chlorination by Cl(2) and Cl(2)O relative to the more abundant (but less reactive) electrophile HOCl. Chlorination rates and products were determined for three aromatic ethers, whose reactivities with FAC increased in the order: 3-methylanisole <1,3-dimethoxybenzene <1,3,5-trimethoxybenzene. Varying solution conditions (pH, [FAC], [Cl(-)]) permitted quantification of regiospecific second-order rate constants for formation of each product by Cl(2), Cl(2)O, and HOCl. Our results indicate that as the reactivity of methoxybenzenes decreases, the importance of Cl(2) and Cl(2)O (relative to HOCl) increases. Accordingly, Cl(2) and Cl(2)O are likely to play important roles in generating DBPs that originate from natural organic matter (NOM) constituents of somewhat moderate reactivity. As [Cl(2)] is proportional to [Cl(-)] and [Cl(2)O] is proportional to [HOCl](2), ramifications for DBP control measures may differ significantly for these precursors compared to more reactive NOM moieties likely to react predominantly with HOCl. In particular, the role of chloride as a chlorination catalyst challenges its traditional classification as an "inert" electrolyte in water treatment processes.

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“…Findings from multiple studies have challenged the assumption that HOCl is the predominant chlorinating agent in free chlorine solutions. The chlorination rates of allyl alcohol, crotonic acid, anisole, biphenyl, p -xylene, , naphthalene, and fluoranthene show a second-order dependence on [HOCl]; most of these studies ,,− attribute this observation to Cl 2 O being the primary chlorinating agent because [Cl 2 O] has a second-order dependence on [HOCl] (Table , eq ). Cl 2 , which is present in free chlorine solutions containing Cl – (eq ), has long been acknowledged as a potent chlorinating agent ,− and oxidant, , especially at pH <6.…”

Section: Chlorine Speciesmentioning

confidence: 99%

Exotic Electrophiles in Chlorinated and Chloraminated Water: When Conventional Kinetic Models and Reaction Pathways Fall Short

Rose

Lau

Prasse

et al. 2020

Environ. Sci. Technol. Lett.

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Halogenation and oxidation of organic matter in chlorinated and chloraminated water are typically attributed to the most abundant electrophiles present. This interpretation sometimes fails to explain laboratory observations, including halogenation kinetics and product distributions. Exotic electrophiles, species commonly overlooked in the environmental literature, can help to resolve these discrepancies. Herein, we review evidence demonstrating the significance of lesser-studied electrophilic chlorinating (Cl2 and Cl2O), brominating (BrCl, BrOCl, and Br2O), and iodinating (H2OI+ and ICl) agents in chlor(am)inated water. The evidence includes reaction rate dependencies on [Cl–], [H+], and [HOCl] that cannot be attributed to the reactivity of hypohalous acids or hypohalites alone. For example, enhancement of chlorination and bromination rates by Cl– implicates Cl2 and BrCl, respectively, as active halogenating agents. Herein, we discuss a new method for quantifying the sensitivity of halogenation to rate enhancement by Cl–. We also discuss complexities that Cl– can impart on iodination kinetics. In addition, we highlight recent insights into radical-mediated reaction pathways and unexpected organic electrophiles in chlorinated water. Finally, we discuss practical implications, identify research needs, and offer recommendations to improve the design of future halogenation experiments. Overall, this review aims to spur new research into underappreciated electrophiles in chlor(am)inated water.

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Kinetics of the chlorination of biphenyl under conditions of waste treatment processes

Cited by 19 publications

References 15 publications

Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr Toward Dimethenamid in Solutions of Bromide + Aqueous Free Chlorine

Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr Toward Dimethenamid in Solutions of Bromide + Aqueous Free Chlorine

Assessing the Reactivity of Free Chlorine Constituents Cl₂, Cl₂O, and HOCl Toward Aromatic Ethers

Exotic Electrophiles in Chlorinated and Chloraminated Water: When Conventional Kinetic Models and Reaction Pathways Fall Short

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Kinetics of the chlorination of biphenyl under conditions of waste treatment processes

Cited by 19 publications

References 15 publications

Reactivity of BrCl, Br2, BrOCl, Br2O, and HOBr Toward Dimethenamid in Solutions of Bromide + Aqueous Free Chlorine

Reactivity of BrCl, Br2, BrOCl, Br2O, and HOBr Toward Dimethenamid in Solutions of Bromide + Aqueous Free Chlorine

Assessing the Reactivity of Free Chlorine Constituents Cl2, Cl2O, and HOCl Toward Aromatic Ethers

Exotic Electrophiles in Chlorinated and Chloraminated Water: When Conventional Kinetic Models and Reaction Pathways Fall Short

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Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr Toward Dimethenamid in Solutions of Bromide + Aqueous Free Chlorine

Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr Toward Dimethenamid in Solutions of Bromide + Aqueous Free Chlorine

Assessing the Reactivity of Free Chlorine Constituents Cl₂, Cl₂O, and HOCl Toward Aromatic Ethers