Bromamines and their bactericidal action

Bromamines and their bactericidal action


“This is a study of the chemistry of bromamines and their bactericidal action. Bromine is used in the sterilization of swimming pools and this information is intended to encourage it use.” The report explains the chemical equilibrium that occurs with the bromination of swimming pools. Bromine is used as a disinfectant in swimming pools and cooling water towers. [1] A limitation of the use of bromine for sterilizing in pools is because of the lack of education of the behaviour of the element in its reactions with other elements found in pools, such as, ammonia and the resultant formation of the combined bromine. The report outlines the bacterial effects, analytical chemistry and the reactions of bromine free and combines bromine in swimming pools. In the report illustrates a study that was made on the chemistry of bromamines and their bacterial action when sterilizing pools.

Explanation of the chemistry that is involved in the article:

The chemistry involved in this article is related to the chemical equilibrium of bromination in swimming pools and how bromine differs from other pool disinfectants. Br2 is very reactive acting as an oxidizing agent and forming bromides with many elements. [2]

When bromine is added to water it hydrolyzes as shown in the equation below:

Br2 + H2O (equilibrium arrow sign inserted here) HOBr + H+ + Br-

The products formed from this reaction are hypobromous acid (HOBr) and hypobromite (HBr). The proportion of each product is dependant on the pH level of the water according to the equation. In this reaction, the equilibrium constant is 5.8x10(to the power of -9).

According to the pH, and molecular structure, bromine forms perbromides; Br3- with an equilibrium constant of 16.0 and Br5- with an equilibrium constant of 40.0. These two perbromides act as strong oxidizing agents, oxidizing urea to nitrogen and carbon dioxide, then forming bromamines as intermediate products.

Focus Questions:

How do the strong bactericidal properties of the bromamines make bromine a greater economical disinfectant for swimming pools than chlorine:

In the reaction between the water and the bromamines, the decomposition of the bromamines occurs at a faster rate than that of chloramines. At a greater extent, no bromine analogue of nitrogen trichloride with difficult to manage properties is formed.

Bromamines are exploited by society when it comes to sterilizing swimming pools, because of the use of a small combined bromine residual which needs no break point in order to achieve the disinfectant stage. Unlike bromamines, when chlorine is used to sterilize a pool, an excess is added to obtain the break point to achieve sterilization. This use of bromine is evidence that has a greater economical property than chlorine.

What effects can bromine have on the human body when submerged in a swimming pool sterilized by bromine:

Why does chlorination of water containing ammonia have a formation known as the break point, yet water that contains bromine does not:


Report: Johannesson.J.K.(1960) The Bromination of Swimming Pools. A.J.P.H. 50 (11), 1731-1736. Internet link:

[1] Lenntech Water treatment & purification Holding B.V. (2009) Disinfectants Bromine. Date retrieved: 1st March 2010.

[2] Sharp, D.W.A. (1990) Dictionary of Chemistry. Great Britain: Penguin Books.

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