Sunlight-Induced Bromate Formation in Chlorinated Seawater

Macalady, Donald L.; Carpenter, James H.; Moore, Cynthia A.

doi:10.1126/science.195.4284.1335

Cited by 79 publications

(29 citation statements)

References 5 publications

(7 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…11 Significant bromate formation in chlorinated water can be observed under some special conditions (e.g., sunlight irradiation). 12 Bromate formation during chlorination of bromide-containing waters is a slow process. In a first step (eqs 1 and 2), bromide is oxidized by hypochlorous acid (HOCl) to form hypobromous acid (HOBr), 13 which is in equilibrium with OBr − with a pK a of 8.…”

Section: ■ Introductionmentioning

confidence: 99%

Enhanced Bromate Formation during Chlorination of Bromide-Containing Waters in the Presence of CuO: Catalytic Disproportionation of Hypobromous Acid

Liu

Gunten

Croué

2012

Environ. Sci. Technol.

109

View full text Add to dashboard Cite

Bromate (BrO 3 − ) in drinking water is traditionally seen as an ozonation byproduct from the oxidation of bromide (Br − ), and its formation during chlorination is usually not significant. This study shows enhanced bromate formation during chlorination of bromide-containing waters in the presence of cupric oxide (CuO). CuO was effective to catalyze hypochlorous acid (HOCl) or hypobromous acid (HOBr) decay (e.g., at least 10 4 times enhancement for HOBr at pH 8.6 by 0.2 g L −1 CuO). Significant halate concentrations were formed from a CuO-catalyzed hypohalite disproportionation pathway. For example, the chlorate concentration was 2.7 ± 0.2 μM (225.5 ± 16.7 μg L −1 ) after 90 min for HOCl (C o = 37 μM, 2.6 mg L −1 Cl 2 ) in the presence of 0.2 g L −1 CuO at pH 7.6, and the bromate concentration was 6.6 ± 0.5 μM (844.8 ± 64 μg L −1 ) after 180 min for HOBr (C o = 35 μM) in the presence of 0.2 g L −1 CuO at pH 8.6. The maximum halate formation was at pHs 7.6 and 8.6 for HOCl or HOBr, respectively, which are close to their corresponding pK a values. In a HOCl−Br − −CuO system, BrO 3 − formation increases with increasing CuO doses and initial HOCl and Br − concentrations. A molar conversion (Br − to BrO 3 − ) of up to (90 ± 1)% could be achieved in the HOCl−Br − −CuO system because of recycling of Br − to HOBr by HOCl, whereas the maximum BrO 3 − yield in HOBr−CuO is only 26%. Bromate formation is initiated by the formation of a complex between CuO and HOBr/ OBr − , which then reacts with HOBr to generate bromite. Bromite is further oxidized to BrO 3 − by a second CuO-catalyzed process. These novel findings may have implications for bromate formation during chlorination of bromide-containing drinking waters in copper pipes. ■ INTRODUCTIONThe formation of bromate during the ozonation of bromidecontaining waters has been intensively studied. 1−5 In the presence of ozone, bromate is produced from the reactions of ozone and ·OH radicals with bromide (Br − ), via several intermediates including hypobromite (BrO − ) and bromite (BrO 2 − ). 5 Because bromate is potentially carcinogenic, it is regulated in potable water at a maximum contaminant level (MCL) of 10 μg L −1 in many countries. 6−8 Moreover, bromate is stable, and there is currently no economically feasible technology to remove it once it is formed. 9 Therefore, the treatment conditions have to be optimized in some cases to mitigate bromate formation while disinfection is still guaranteed (e.g., ammonia addition and lowering the pH 9 ).

show abstract

Section: ■ Introductionmentioning

confidence: 99%

Enhanced Bromate Formation during Chlorination of Bromide-Containing Waters in the Presence of CuO: Catalytic Disproportionation of Hypobromous Acid

Liu

Gunten

Croué

2012

Environ. Sci. Technol.

109

View full text Add to dashboard Cite

show abstract

“…The chlorination of drinking water and sewage effluent may result in the formation of many chemical compounds, including chlorine-produced oxidants (CPOs), such as hypochlorous acid (HOCI), hypochlorite (OCI-) in freshwater; hypobromous acid (HOBr), hypobromite (OBr-) in saltwater; trihalomethanes (THMs), such as CHCl3 in freshwater, bromoform (CHBr3) in saltwater; haloacetonitriles and chlorinated amines (1)(2)(3)(4). Other chemical compounds in water and sewage that serve as precursor molecules for the de novo synthesis of chlorinated compounds have clearly been documented (5)(6)(7).…”

Section: Introductionmentioning

confidence: 99%

Lethal and sublethal effects of chlorine, phenol, and chlorine-phenol mixtures on the mud crab, Panopeus herbstii.

Key¹,

Scott²

1986

Environ Health Perspect

View full text Add to dashboard Cite

The mud crab, Panopeus herbstii, was acutely exposed (96-hr) to chlorine-produced oxidants (CPO), phenol, and a CPO-phenolic mixture (1:1) to determine lethal and sublethal effects. The 96-hr (LCro) values were determined for each individual compound and mixture. Additionally, whole-animal respiration rates were measured following acute exposure to sublethal concentrations of each compound or mixture. Phenol uptake/depuration rates were measured in the phenol and CPO-phenol mixture concentrations. Sublethal studies indicated that only acute exposure to sublethal concentrations of CPO caused altered respiration rates. After 96-hr depuration, metabolic rates in all CPO-exposure crabs generally returned to control rates. Uptake/depuration rate studies indicated significantly lower phenol uptake rates in crabs exposed to the CPO-phenol mixture. These findings suggest that the less-than-additive toxicity of the CPO-phenol mixture may result from lowered uptake/depuration rate kinetics and indicate that the discharge of chlorinated-phenolic waste may not result in additive and/or synergistic interactions, but rather in less-than-additive effects on decapod aquatic species.

show abstract

“…As the chlorine decays and is diluted by ambient waters, the concentration of bromate increases, potentially reaching levels toxic to downstream organisms (Table 3- 6). The lack of information on the toxicity of chlorine-seawater reaction products to marine organisms (Macalady et al, 1977) restricts the further assessment of chlorine discharges; however, the sublethal effects of these compounds could potentially have a significant effect. Approximately 140,000 kg (155 tons) of ammonia will be stored on the Pilot Plant, and may be released into the environment by slow leaks or a catastrophic spill.…”

Section: 343mentioning

confidence: 99%

“…Macalady et al (1977) studied the disappearance of residual oxidants (chlorine, hypochlorous acid, hypochlorite ions, inorganic and organic chloramines, and other compounds) in chlorinated seawater exposed to sunlight. Samples exposed to full midday sunlight underwent 80% degradation in less than 1 hour and 9S% degradation after 2 hours.…”

Section: 343mentioning

confidence: 99%

Environmental Assessment Ocean Thermal Energy Conversion (Otec) Pilot Plants

Sullivan¹

1981

View full text Add to dashboard Cite

Sunlight-Induced Bromate Formation in Chlorinated Seawater

Cited by 79 publications

References 5 publications

Enhanced Bromate Formation during Chlorination of Bromide-Containing Waters in the Presence of CuO: Catalytic Disproportionation of Hypobromous Acid

Enhanced Bromate Formation during Chlorination of Bromide-Containing Waters in the Presence of CuO: Catalytic Disproportionation of Hypobromous Acid

Lethal and sublethal effects of chlorine, phenol, and chlorine-phenol mixtures on the mud crab, Panopeus herbstii.

Environmental Assessment Ocean Thermal Energy Conversion (Otec) Pilot Plants

Contact Info

Product

Resources

About