Aqueous Chlorine Chloramines

The chemistry of chloramines has been reviewed by Kovacic et al. (1970). In water, depending on pH and concentration, monochloramine (NH2CI), dichloramine (NHCI2), or trichloramine (NCI3), may be present, in addition to organic chloramines derived from amines. 

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Dodd, M.C., Vu, N.D., Ammann, A. et al. (2006) Kinetics and mechanistic aspects of As(III) oxidation by aqueous chlorine, chloramines, and ozone relevance to drinking water treatment. Environmental Science and Technology, 40(10), 3285-92. 

When chlorine is passed into aqueous ammonia, ammonium chloride and nitrogen are formed. If, however, sodium chloratefi) (hypochlorite) is used instead of chlorine, chloramine is first formed ... 

Chemical precipitation Precipitation induced by addition of chemicals the process of softening water by the addition of lime and soda ash as the precipitants. Chloramines Compounds formed by the reaction of hypochlorous acid (or aqueous chlorine) with ammonia. 

Cbemical/Physical. The aqueous chlorination of indole by hypochlorite/hypochlorous acid, chlorine dioxide, and chloramines produced oxindole, isatin, and possibly 3-chloroindole (Lin and Carlson, 1984). 

Lin, S. and Carlson, R.M. Susceptibility of environmentally important heterocycles to chemical disinfection reactions with aqueous chlorine, chlorine dioxide, and chloramine. Environ. Sci. Technol, 18(10) 743-748, 1984. 

Aqueous chlorine, however, reacts with other possible solutes such as H2S (Eq. 14.25), NH3 (giving chloramine, NH2CI), and organic matter, so the chlorination plant operator arranges for 0.2 to 0.5 ppm chlorine equivalent to remain in the water 5 minutes after treatment, as this is enough for continued bactericidal action en route to the user. 

Table 17.1 shows the standard enthalpy change as a function of pH for both aqueous chlorine and chloramines, and Table 17.2 shows the various possible values of the universal gas constant. 

The rate of oxidation of some a-amino acids to the corresponding aldehydes, ammonia, and carbon dioxide by A-chloronicotinamide (NCN) in acidic medium is first-order in both oxidant and HCl and fractional order in amino acid nicotinamide, the reduction product of NCN, has a retarding effect on the rate. Molecular chlorine has been postulated as the reactive oxidizing species in the reaction. " Deuterium solvent isotope effects suggest decomposition through two processes in the oxidation of Ala-Gly and Pro-Gly by aqueous chlorine elimination then imine hydrolysis in alkaline medium and in acidic medium the chloramine dipeptide disproportionates to N, A-dichloramine dipeptide. 

Barium chloride Barium salts, aqueous Carbonic acid Castor oil Chlophen A 60 Chloral hydrate, aqueous Chloramine, aqueous Chloride of lime, aqueous Chlorine, wet + dry Chloroacetic acid Chlorobenzene Chloroform Chloromethyl o-Chloronaphthalene Chloroprene Chlorosulfonic acid Chromic acid Citric acid... 

Both chloramine-T and dichloramine-T slowly liberate hypochlorous aeid in eontaet with water and are therefore employed as antiseptics the former is employed in the form of a dilute (e.g., 0-2 per eent.) aqueous solution, and the latter (which is insoluble in water) as a solution in an organic solvent, such as a chlorinated paraffin. 

Reagents similai to those used in the analysis of chloiine are commonly employed in the quantitation of gaseous and aqueous chloiine dioxide as well as its reaction coproducts chlorine, chlorite, and chlorate. The volatihty of the gas from aqueous solutions as well as its reactivity to light must be considered for accurate analysis. Other interferences that must be taken into account include other oxidizers such as chloramine, hydrogen peroxide, permanganate, and metal impurities such as ferrous and ferric iron. 

Chloramine-B (CAB, PhS02NClNa) and chloramine-T (CAT, p-Me-C6H4S02NClNa) have also been used for the oxidation of sulphoxides107-115. The required sulphone is produced after initial attack by the sulphoxide sulphur atom on the electrophilic chlorine-containing species, forming a chlorosulphonium intermediate as shown in equation (34). These reactions take place at room temperature, in water and aqueous polar solvents such as alcohols and dioxane, in both acidic and basic media. In alkaline solution the reaction is slow and the rate is considerably enhanced by the use of osmium tetroxide as a catalyst115. 

Acidification of chloramine T with sulfuric acid produces the formation of dichloramine T (DCT) and hypochlorous acid (HCIO), species which react with C=C bonds of the butadiene units. The effectiveness of the treatment is ascribed to the introduction of chlorine and oxygen moieties on the mbber surface. A decrease in the pH of the chloramine T aqueous solutions produced more extended surface modifications and improved adhesion properties in the joints produced with waterborne polyurethane adhesive (Figure 27.9). The adhesive strength obtained is slightly lower than that obtained for the rubber treated with 3 wt% TCI/MEK, and its increases as the pH of the chloramine T solution decreases (Figure 27.9). A cohesive failure in the rubber is generally obtained. 

Chemical/Physical. Kanno et al. (1982) studied the aqueous reaction of benzene and other aromatic hydrocarbons (toluene, xylene, and naphthalene) with hypochlorous acid in the presence of ammonium ion. They reported that the aromatic ring was not chlorinated as expected (forming chlorobenzene) but was cleaved by chloramine forming cyanogen chloride (Kanno et al, 1982). 

Chemical/Physical. Under atmospheric conditions, the gas-phase reaction of o-xylene with OH radicals and nitrogen oxides resulted in the formation of o-tolualdehyde, o-methylbenzyl nitrate, nitro-o-xylenes, 2,3-and 3,4-dimethylphenol (Atkinson, 1990). Kanno et al. (1982) studied the aqueous reaction of o-xylene and other aromatic hydrocarbons (benzene, toluene, w and p-xylene, and naphthalene) with hypochlorous acid in the presence of ammonium ion. They reported that the aromatic ring was not chlorinated as expected but was cleaved by chloramine forming cyanogen chloride. The amount of cyanogen chloride formed increased at lower pHs (Kanno et al., 1982). In the gas phase, o-xylene reacted with nitrate radicals in purified air forming the following products 5-nitro-2-methyltoluene and 6-nitro-2-methyltoluene, o-methylbenzaldehyde, and an aryl nitrate (Chiodini et ah, 1993). 

Wei-Hsiang, C. and Young, T.M. (2008) NDMA formation during chlorination and chloramination of aqueous diuron... 

Since chloramine itself is prepared by chlorination of ammonia, hydrazine is generally prepared by treatment of excess ammonia with chlorine. The similarity to H2O2 is exemplified by the detection of hydrazine at the anode in electrolysis of ammonium salts, just as H2Q2 or its derivatives can result from electrolysis of aqueous acid solutions. 

Sodium hypochlorite is obtained as a ca. 4.7 mol/L solution by mixing chlorine and sodium hydroxide with cooling in a molar ratio of 1 2 (see Fig, 1.4.-3). This is diluted to ca. 1 mol/L and reacted with an aqueous ammonia solution (ca. 15%) at temperatures around 0°C (with cooling) forming chloramine and sodium hydroxide. The yield is almost quantitative. 

A similar reaction with (CF3)2NH is described (226). A small amount of SFgCCFslNNCCFglSFg is obtained during the photolysis of SFgNCCDCFg (210). A hydrol3d.ically stable liquid, SFgCCFjlNNCCFglSFg, boils at 103-104°C. It is not attacked by aqueous alkali at 100°C. It reacts with chlorine to give the chloramine C1N(SF5)(CF3), which adds to perfluoropropylene in a fashion similar to that of BrNtCFgla (227). 

Generation of chloramines requires the same equipment as chlorination (gaseous or aqueous hypochloramination), plus equipment for adding ammonia (gaseous or aqueous). The information for calculating the corrosion indexes for final corrosion control and for determining the CT values for secondary chloramination process control can be found in Appendix A and Appendixes D-E, respectively. 

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