Bromate
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221241449
2008-06-23T17:52:33Z
65.60.113.243
[[Image:Bromate-3D-vdW.png|thumb|right|150px|A [[space-filling model]] of the bromate anion]]
The '''bromate''' [[ion|anion]], {{bromine}}{{oxygen|3|-}}, is a [[bromine]]-based [[oxyanion|oxoanion]]. A '''bromate''' is a [[chemical compound]] that contains this ion. Examples of bromates include [[sodium bromate]], ({{sodium}}{{bromine}}{{oxygen|3}}), and [[potassium bromate]], ({{potassium}}{{bromine}}{{oxygen|3}}).
Bromates are formed many different ways in municipal drinking water. The most common is [[ozone]] and [[bromide]] ion react according to the following abbreviated reaction:
:{{bromide||-}} + {{oxygen|3}} → {{bromine}}{{oxygen|3|-}}
Electrochemical processes, such as formation of [[hypochlorite]], will also form bromate, when bromide ion is present in the brine solution used to make hypochlorite.
[[Photoactivation]] will also promote [[chlorine dioxide]] or (recently, see below) liquid or gaseous chlorine to also produce bromate in bromide-containing water, when exposed to sunlight
Bromate in drinking water is undesirable because it is a suspected human [[carcinogen]].<ref>{{cite web
|url= http://www.inchem.org/documents/iarc/vol73/73-17.html
|work= [[International Agency for Research on Cancer]]: Summaries and Evaluations
|title= Potassium Bromate (Group 2B)
|publisher= [[Canadian Centre for Occupational Health and Safety]]
|accessdate= 2008-03-09
}}</ref><ref>{{cite journal
|url= http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=2269236
|title= Toxicity and carcinogenicity of potassium bromate--a new renal carcinogen
|journal= [[Environmental Health Perspectives]]
|month= July
|year= 1990
|volume= 87
|pages= 309–335
|accessdate= 2008-03-09
|doi= 10.2307/3431039
|author= Kurokawa, Yuji
|pmid= 2269236
}}</ref><!-- The only organisms that developed tumors with potassium bromate, also developed tumors with potassium carbonate. Sodium bromate has not been observed to produced tumors in organisms, and it has been extensively tested --> The presence of it in Coca Cola's [[Dasani]] forced a recall of that product in the [[UK]].<ref>{{cite news
|url= http://news.bbc.co.uk/1/hi/business/3550063.stm
|title= Coke recalls controversial water
|work= [[BBC News]]
|date= 2004-03-19
|accessdate= 2008-03-09
}}</ref> Proposals to reduce bromate formation include switching to enclosed atmospheric tank contact systems, lowering the water pH to between 5.9 - 6.3, and limiting the doses of ozone.
In laboratories bromates can be synthesized by dissolving {{bromine|2}} in a concentrated solution of [[potassium hydroxide]] (KOH). The following reactions will take place:
:{{bromine|2}} + 2 OH<sup>-</sup> → {{bromine||-}} + {{bromine}}{{oxygen||-}} + {{hydrogen|2}}{{oxygen}}
:3 {{bromine}}{{oxygen||-}} → {{bromine}}{{oxygen|3|-}} + 2 {{bromine||-}}
==Reservoir pollution==
On December 14, 2007, it was announced by the [[Los Angeles Department of Water and Power]] (LADWP) that the Silver Lake and Elysian [[reservoir]]s were going to be drained due to bromate contamination. Bromate usually forms when bromide is purified using ozone, a method used at filtration plants. In the case of the Silver Lake and Elysian reservoirs, however, a combination of bromide from well water, chlorine and sunlight formed bromate. The decontamination took 4 months and resulted in the discharge of over 600 million gallons of contaminated water.<ref>{{cite news
|url= http://www.knbc.com/news/14858647/detail.html
|title= DWP To Drain 2 Reservoirs After Potentially Harmful Chemical Found
|date= 2007-12-14
|work= [[KNBC]] News
|accessdate= 2008-03-09
}}</ref>
On June 9, 2008 the LADWP began covering the surface of the 10 acre, 58 million gallon open Ivanhoe reservoir with black, plastic balls to block the sunlight which causes the naturally present bromide to react with the chlorine used in treatment. It will require 30 million of the 40 cent balls to cover the Ivanhoe and Elysian reserviors.<ref>{{cite news
|url=http://www.latimes.com/news/local/la-me-balls10-2008jun10,0,5878575.story
|title= DWP drops 400,000 balls onto Ivanhoe Reservoir}}
</ref>
==References==
{{reflist}}
[[Category:Oxoanions]]
[[Category:Bromates| ]]
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