Chlorine hypochlorous acid

FIGURE 15.10 Variation with pH of proportions of chlorine, hypochlorous acid, and hypochlorite ion in 0.05 M chlorine water at 25°C. (Data from Nevell [25].)... 

FIGURE11.10 Amount of chlorine, hypochlorous acid and hypochlorite present in aqueous solution at different pH-values. 

Calcium hypochlorite Chlorine Hypochlorous acid Phosphorus oxychloride Phosphorus pentachloride... 

Chlorine (hypochlorous acid and hypochlorite) Monochlororamine Bromodichloromethane Dibromochloromethane Bromoform ... 

In most cases during chlorination, hypochlorous acid is an intermediate, since it reacts rapidly with base to form hypochlorite as follows ... 

Electrolytic cells are also used in a variety of devices - and appliances " to produce dilute solutions of electrolyzed water for cleaning and sanitization. Miniature, battery-powered cells are used to generate hypochlorite in handheld sprayers and small portable water disinfection devices. " " The brine may be saturated or have 1-5 g L of salt. An acidic solution of chlorine, hypochlorous acid, and possibly chlorine dioxide is obtained from the anode of a divided cell. It typically has 10-100 mg L of available chlorine and pH values of 2-4. Its stability is poor, and the volatile oxidants are rapidly lost from open solutions. A neutral solution of hypochlorous acid and sodium hypochlorite is dispensed from undivided cells or by combining effluents from the anode and cathode. It typically has 80-100 mg L of available chlorine and pH 5-8. Devices to make 500-1000 mg L" of available chlorine are also available. Neutral solutions made using larger versions of these devices are bottled and sold in some regions. 

Addison, C.C., The oxides and oxyacids of chlorine hypochlorous acid and the hypochlorites, in Mellor s Comprehensive Treatise on Inorganic and Theoretical Chemistry, Supplement II, Part I, Longmans, London, 1956, p. 544. 

Dry chlorine and wet chlorine (hypochlorous acid) will react with organic substances containing double or triple bonds to yield vicinal dichlorides and chlorohydrins respectively. For example, hypochlorous acid will react with fatty acids in lipids such as oleic acid at pH 2 to 10, to produce 9-chloro-lO-hydroxystearic acid, while dry chlorine will produce a mixture of chlorinated products. 

Chlorination is the most common method of disinfection, thanks to its low cost. Cl can be oxidized to yield active chlorine species (dissolved chlorine, hypochlorous acid HclO, and hypochlorite ions CIO ) with beneficial disinfecting effects (Eqs. 1 and 2) [14]. Chlorine-mediated electrolysis is particularly suitable for the treatment of wastewater with high sodium chloride concentrations, such as olive oil wastewater, and textile and tannery effluents. The main drawback of this indirect oxidation is the likely formation of chlorinated organic byproducts. 

The oxidation potential of halogens is the result of their strong affinity to electrons. The introduction of any of the unstabilized or stabilized forms of chlorine produce hypochlorous acid (HOCl) and hypochlorite ion (OCl ) when dissolved in water. The total amount of both species is referred to as free available chlorine. Hypochlorous acid is the primary chemical responsible for sanitation. The hypochlorous acid and hypochlorite ion equilibrium is illustrated by the following equation ... 

N-chloramines the experiments of Friberg (1956) using radioactive Cl and in 1957 using radioactive P are especially informative. In view of the results of these experiments it is concluded that contact oxidation reactions of chlorine/hypochlorous acid at the bacterial cell wall cause destructive permeability changes which lead to the kill of the microbial cell before chlorine or N-chlor-amines accumulate in the microbe cell. 

Saunier and Regnier [6] describe a continuously operating amperometric apparatus for the measurement of free chlorine, hypochlorous acid, and combined chlorine in water samples. The apparatus contains two amperometric measuring units. One measures the total chlorine in untreated water and the other measures the combined chlorine content in water to which NO3 has been added as reducing agent. The free chlorine can be calculated from the difference. 

Children who regularly swim in indoor swimming pools have been found to have higher rates of asthma than those who do not. The cause has been attributed to the reaction of disinfectant chlorine (hypochlorous acid) with organic matter (e.g., perspiration, saliva, and urine) to produce lipophilic/hydrophilic mixtures of disinfection by-products that include THMs, trihaloacetic acids, and chloramines that are inhaled by swimmers as vapors and aerosols [63]. Similar inCTeases in asthma prevalence have been reported for lifeguards who work in indoor swimming pools [64]. 

Song, W., Wei, S., Zhou, Y, et al., 2010. Inhibition of lung fluid clearance and epithelial Na+ channels by chlorine, hypochlorous acid, and chloramines. J. Biol. Chem. 285, 9716-9728. 

US EPA, 1994. Drinking Water Criteria Document for Chlorine, Hypochlorous Acid and Hypochlorite Ion. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Cincinnati, OH. 

Chlorine (CU) is added for disinfection in the form of chlorine gas or a hypochlorite. Chlorine gas dissolves in water. The resulting solutions form an equilibrium between chlorine, hypochlorous acid (HOCl) and the hypochlorite ion (OCf) as shown below ... 

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