Chloramines monochloramine

Reacts with chlorine forming chloramines monochloramine, dichloramine and nitrogen trichloride ... 

Chlorine forms carbonyl chloride, COCl with carbon monoxide suhuryl chloride SO2CI with sulfur dioxide and chloramines (monochloramine, NH2CI, and dichloramine, NHCI2) with ammonia. Chloramines are often found at trace concentrations in sewage wastewater following chlorine treatment. 

A number of perhalides aie known, and one of the most stable is ammonium tetiachloioiodide [19702 3-3] NH IQ. Ammonia reacts with chlorine in dilute solution to give chloramines, a reaction important in water purification (see Cm,ORAMINES AND BROMAMINEs). Depending upon the pH of the water, either monochloramine [10599-90-3] NH2CI, or dichloramine [3400-09-7] NHCI2, is formed. In the dilutions encountered in waterworks practice, monochloramine is neady always found, except in the case of very acidic water (see Bleaching AGENTS Water). 

SuperchlorinationShock Treatment. Superchlorination or shock treatment of pool water is necessary since accumulation of organic matter, nitrogen compounds, and algae consumes free available chlorine and impedes disinfection. Reaction of chlorine with constituents of urine or perspiration (primarily NH" 4, amino acids, creatinine, uric acid, etc) produces chloramines (N—Cl compounds) which are poor disinfectants because they do not hydrolyze significantly to HOCl (19). For example, monochloramine (NH2CI) is only 1/280 as effective as HOCl against E. coli (20). 

In reahty the chemistry of breakpoint chlorination is much more complex and has been modeled by computer (21). Conversion of NH/ to monochloramine is rapid and causes an essentially linear increase in CAC with chlorine dosage. Further addition of chlorine results in formation of unstable dichloramine which decomposes to N2 thereby causing a reduction in CAC (22). At breakpoint, the process is essentially complete, and further addition of chlorine causes an equivalent linear increase in free available chlorine. Small concentrations of combined chlorine remaining beyond breakpoint are due primarily to organic chloramines. Breakpoint occurs slightly above the theoretical C1 N ratio (1.75 vs 1.5) because of competitive oxidation of NH/ to nitrate ion. Organic matter consumes chlorine and its oxidation also increases the breakpoint chlorine demand. Cyanuric acid does not interfere with breakpoint chlorination (23). 

Chloramine (Chloramide, Monochloramine), C1NH2, mw 51.48, N 27.2% a colorl liq or ciysts, mp -66°, decomps above the mp (Refs 2 8). It has an IR absorption peak at 2430A which can be used for spec trophotome trie analysis (Ref 3). It is unstable at room temp except in aq soln, so it is stored and handled in this form (Ref 4) CA Registry No 10599-90-3... 

Ammonia (NH3) and hypochlorite ion (OC1-) combine to produce three different chloramine species—that is, compounds that are derivatives of ammonia in which one or more of the hydrogen atoms has been replaced by a chlorine atom. In order of increasing degree of chlorine substitution, these chloramines are named monochloramine (NH2CI), dichloramine (NHCh), and nitrogen trichloride (NCI3) ... 

Chlorination and chloramination of a widely used antibacterial additive, triclo-san, which is used in many household personal care products, results in the formation of chloroform, 5,6-dichloro-2-(2,4-dichlorophenoxy)phenol, 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol, 4,5,6-trichloro-2-(2,4-dichlorophenoxy)phenol, 2, 4-dichlorophenol, and 2,4,6-trichlorophenol [119]. The reaction of triclosan with monochloramine is slow, however, compared to chlorine [120]. The chlorophenox-yphenols are formed via bimolecular electrophilic substitution of triclosan. 

Note that trichloramine is an unstable gas that quickly dissociates into its components. The formation of the particular species of chloramines formed is dependent on pH. Trichloramine is formed at pH less than 4.4. Dichloramine is formed at pH 4.4 to 6.0. Monochloramine is the most prevalent species at pH greater than about 7. 

The exceptions are chloramines of valine, leucine, and isoleucine, which form semistable chloramines that remain in the reaction medium for several hours (Z4). The mechanism of aldehyde formation from the intermediary amino acid a-chloramines produced either by HOC1 treatment or by the MP0-H202-C1- system was recently verified with use of NMR spectra. The study made possible the identification of short-lived products of the reaction, and confirmed the role of the unstable monochloramine of the a-amino group as the intermediate (H12). 

The three chemicals most commonly used as primary disinfectants are chlorine, chlorine dioxide and ozone. Monochloramine, usually referred to as chloramine, is used as a residual disinfectant for distribution. 

Chloramines have been known since the beginning of the 19th century, and used in water treatment since the beginning of the 20th century. They have the general formula NH3 Cl (x = 0-3). Under normal conditions, monochloramine (NH2CI) is the predominant chloramine in aqueous solutions. 

As stated above, chloramines are produced in solution when CI2 or C10 reacts with NH3 or NH ". Monochloramine is produced in aqueous solution by a fast reaction between HCIO and NH3 (99% complete in < 1 min). For water treatment, it is nor-... 

Consider the formation of the nitrate ion. The oxidation state of nitrogen in the nitrate ion is +5. Thus, this ion would not be formed from ammonia, because this would need the abstraction of eight electrons. If it is formed from the monochloramine, it would need the abstraction of six electrons, and if formed from the dichloramine, it would need the abstraction of four electrons. Thus, in the chloramine reactions with HOCl, the nitrate is formed from the dichloramine. We will, however, compare which formation forms first from the dichloramine trichloramine or the nitrate ion. The oxidation state of the nitrogen atom in trichloramine is -i-3. Thus, to form the trichloramine, two electrons need to be abstracted from the nitrogen atom. This may be compared to the abstraction of four electrons from the nitrogen atom to form the nitrate ion. Therefore, the trichloramine forms first before the nitrate ion does. 

Now, let us discuss the final fate of trichloramine during disinfection. In accordance with the chloramine reactions [Reactions (17.34) to (17.36)], by the time three moles of HOCl have been added, a mole of trichloramine would have been formed. This, however, is not the case. As mentioned, while the monochloramine decomposes in a stepwise fashion to convert into the dichloramine, its destruction into the nitrogen gas intervenes. Thus, the eventual formation of the dichloramine would be less in fact, much, much less, since, as we have found, formation of the gas is favored over the formation of the dichloramine. In addition, monochloramine and dichloramine, themselves, react with each other along with HOCl to form another gas N2O [NH2CI -1-NHCI2 + HOCl N2O -I- 4H" -I- 4CL]. Also, there may be more other side reactions that could occur before the eventual formation of the dichloramine from monochloramine. Overall, as soon as the step for the conversion of the dichloramine to the trichloramine is reached, the concentration of dichloramine is already very low and the amount of trichloramine produced is also very low. Thus, if, indeed, trichloramine has a disinfecting power, this disinfectant property is useless, since the concentration is already very low in the first place. This is the reason why combined chlorine is only composed of the monochloramine and the dichloramine. Also, it follows... 

In waters and wastewaters, organic amines and their decomposition products such as ammonia may be present, hi addition, ammonia may be purposely added for chloramine formation to produce chlorine residuals in distribution systems. Also, other organic snbstances snch as organic amides may be present as well. Thus, from point A to B, chloro-organic compounds and organic chloramines are formed. Ammonia will be converted to monochloramine at this range of chlorine dosage. 

Beyond point B, the chloro-organic compounds and organic chloramines break down. Also, at this range of chlorine dosage, the monochloramine starts to convert to the dichloramine, but, at the same time, it also decomposes into the nitrogen gas and, possibly, other gases as well. These decomposition reactions were addressed previonsly. 

As the curve continues to go downhill from point B, the dichloramine converts to the trichloramine, the conversion being complete at the lowest point indicated by breakpoint. As shown, this lowest point is called the breakpoint. In addition, nitrates will also be formed from the dichloramine before reaching the breakpoint. In fact, other snbstances wonld have been formed as decomposition products from monochloramine and dichloramine, as well as other snbstances would have been formed as decomposition prodncts from the chloro-organic compounds and organic chloramines. 

Combined chlorine—Chloramines composed of monochloramines and dichloramines. 

Using a preformed monochloramine solution (the third method) creates the same problem of producing less effective organic chloramines, if organonitrogen compounds are present. 

The mix of species produced depends on the ratio of chlorine to ammonia and the pH of the water. In the pH range of 7-8 with a chlorine-to-ammonia ratio (by weight) of 3 to 1, monochloramine is the principal product. At higher chlorine-to-ammonia ratios or at lower pH values (5-7), some dichloramine will be formed. If the pH drops below 5, some nitrogen trichloride (often erroneously called trichloramine ) may be formed. Nitrogen trichloride formation should be avoided because it imparts undesirable taste and odor to the water. To compare the disinfection efficiencies of secondary chlorination with secondary chloramination, a design engineer should also consider the effect of each process on corrosion control (see Appendix A). 

Modifications were implemented between 1976 and 1983. Chloramination of the finished water was introduced in 1976 to reduce free chlorine contact times and THM levels. Ammonia was added to convert free chlorine to monochloramine. The monochloramine reduced contact time from 96 to 24 h, provided a stable residual in the distribution system, improved the organoleptic properties of the water, and reduced the corrosion rates associated with the use of free chlorine. Adequate disinfection was ensured by maintaining a free chlorine residual of 2-3 mg/L throughout the plant treatment process. THM formation potential within the treatment process was reduced by 40% under summer conditions. 

Monochloramine is a more effective oxidizing agent than di- and trichtoramines. In potable water systems, monochloramine is often the predominant species present. Combined chiorine is iess aggressive, more persistent, and reacts more stowty with oxi-dizable materiats and bacteria (3). Some utilities prefer chloramines over free chlorine for disinfection because it has a lower potential to form THMs and has tess taste and odor probtems. Atso, it travets further in the typical distribution system. 

AI3-16452 Annogen Benzene chloramine Benzene-sulfo-sodium chloramlde Benzenesulfochloramide, N-chloro-, sodium salt Benzenesulfochloramide sodium Benzenesulfonamide, N-ohloro-, sodium salt Caswell No. 169 Chloramin B Chloramine B Chlordetal Chlorogen N-Chlorobenzenesulfonamide sodium N-Chloro-N-sodiobenzenesulfonamide EINECS 204-847-9 ERA Pesticide Chemical Code 076501 HSDB 3422 Khloramin B Monochloramine B Neomagnol NSC 75446 Sodium, (chloro(phenylsulfonyl)amino)- Sodium, (N-... 

Among disinfectants, such as inorganic chloramines, chlorine and chlorine dioxide, the latest is the most efficient disinfectant for bacteria, having both the lowest effective dose and the shortest contact time [16], but human health problems can arise with its use [31]. Increasing pH increases the bactericidal activity of chlorine dioxide [32]. However, at higher pH values (> 7.0) chlorine becomes less effective because hypochlorite ions are formed. Increased pH levels (> 7.5) also convert dichloramines to monochloramines which are less bactericidal [16]. On the other hand, monochloramines are more efficient viricides than dichloramines [33]. 

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