Apparent Reactivity of Bromine in Bromochloramine Depends on Synthesis Method: Implicating Bromine Chloride and Molecular Bromine as Important Bromine Species

Modeling chloramine stability and disinfection byproduct formation in groundwater high in bromide

“…When simulated bromamine levels (mainly NH 2 Br) in chlorine preoxidation experiments were at their highest (times <30 min), Figure 2 shows the predicted total oxidant and measured total chlorine concentrations were similar in each experiment (within ±10% in Figure S3). These results suggest DPD‐based total chlorine method can measure the sum of chlorinated and brominated oxidant concentrations, which has also been found in other studies for both bromamines and bromochloramine (Allard, Cadee, et al, 2018; Allard, Wei, et al, 2018; Brodfuehrer et al, 2022; Palin, 1975; Sollo et al, 1971; Valentine, 1986). A few studies have shown that organic amines, dichloramine (NHCl₂), trichloramine (NCl₃), and free chlorine do not interfere with the indophenol method because the substituted phenol, which produces a signal upon oxidation, reacts specifically with NH ₂ Cl (Harp, 2000; Lee et al, 2007).…”

“…Because DOM preoxidized by chlorine should have fewer oxidizable moieties than DOM preoxidized by KMnO 4 (Colthurst & Singer, 1982; Hidayah & Yeh, 2018; Westerhoff et al, 2004), it is unlikely that DOM reacted directly with NHBrCl in Experiments 1–3. Depending on the order in which chlorine and ammonia are added to produce chloramines, NHBrCl formation involves different intermediates including HOBr, Br 2 , and BrCl (Allard, Cadee, et al, 2018; Brodfuehrer et al, 2022; Luh & Mariñas, 2014), which have been shown to be reactive with DOM (Brodfuehrer et al, 2022; Mensah et al, 2023). Because chlorine and ammonia addition orders were different in KMnO 4 and chlorine preoxidation experiments (Figure 1), differences in the NHBrCl formation pathways may explain why measured ∆Total Chlorine‐NH₂Cl values and simulated NHBrCl levels were similar following KMnO 4 preoxidation but not chlorine preoxidation.…”

“…Although few studies have investigated the role of brominated amines in DBP formation (Criquet & Allard, 2021), a recent investigation found that bromamines can yield substantial levels of bromoform when exposed to more reactive DOM associated with aromatic and phenolic moieties (Mensah et al, 2023). Although there is a growing body of research elucidating bromamine formation and decay mechanisms as well as kinetics in laboratory pure water Brodfuehrer et al, 2022;Mensah et al, 2022;Wahman et al, 2017), more research is needed to evaluate the impact bromide has on the stability of a chloramines in natural waters and the ability of kinetic models to predict NH 2 Cl decomposition. Moreover, the accuracy of models developed under ideal conditions to predict NH 2 Cl stability in natural waters has seldom been explored (Mensah et al, 2023), and there remains a need for predictive relationships between bromide concentrations and NH 2 Cl decay.…”

Inactivation of Edwardsiella tarda and Vibrio harveyi by Chlorination in Seawater

“…In particular, NH 2 Cl and NH x Br y -dominant agents showed markedly low microbial inactivation efficacies (more than 2-order of magnitude lower than those of HOCl dominant agents) due to their weak oxidation power, , which is consistent with the observations for other microorganisms . The inactivation efficacy of the NHBrCl-dominant agent was not discussed because the reactivity of NHBrCl is known to be lower than that of NH x Br y . Considering the results of kinetic modeling (Figure ) and the microbial inactivation efficacies of different CPO-dominant agents (Figure ), it is evident that the greater inactivation of microorganisms at pH 7.1 than at pH 8.2 (Figures and ) in seawater is due to the considerably reduced disinfectant effectiveness of NH 2 Cl and NH x Br y in contrast to HOBr.…”

“…50 The inactivation efficacy of the NHBrCl-dominant agent was not discussed because the reactivity of NHBrCl is known to be lower than that of NH x Br y . 51 Considering the results of kinetic modeling (Figure 4) and the microbial inactivation efficacies of different CPO-dominant agents (Figure 5), it is evident that the greater inactivation of microorganisms at pH 7.1 than at pH 8.2 (Figures 2 and 3) in seawater is due to the considerably reduced disinfectant effectiveness of NH 2 Cl and NH x Br y in contrast to HOBr. Additionally, the lower efficacies of microbial inactivation in seawater compared with that in DI water (compare the Ct values in Tables 2 and S3) can also be explained by the significant evolution of NH 2 Cl and NH x Br y in seawater.…”