Chlorine in swimming pools

Question 5.20 Why Does Chlorine in Swimming Pools Work Best at Night ... 

Why does chlorine in swimming pools work best at night See p. 70. 

Why is hydrogen peroxide kept in dark plastic bottles See p. 40. Why does chlorine in swimming pools work best at night See p. 70. 

The qualitative observations of the Allworden reaction are produced by relatively large concentrations of chlorine or bromine water. Fair and Gupta [41] were the first to investigate the effect of chlorine water on hair, at the parts-per-million level, in an attempt to assess the effects of chlorine in swimming pools on hair. 

You may be surprised to find out that you encounter many of these elements on a daily basis. Some of them are important for industry (such as silicon used in electronics) wherecis others, such as carbon and nitrogen, are important for biology. Also, don t forget the chlorine in swimming pools and helium in balloons. 

Uses Stabilizer for chlorine in swimming pool water to prepare chlorinated isocyanurates for use as disinfectants, bleaches, sanitizers, and cleaners... 

This reaction is a key part of iodometric titrations, which are used for quantitative determination of oxidants in aqueous samples, such as oxygen saturation in ecological samples or active chlorine in swimming pool water. 

Interestingly, practically all studies on disinfection of biofilms focus on already existing biofilms and not on their prevention. Biocides can be effective in prevention of biofilm formation, as practical experience with chlorine in swimming pools proves. This aspect has not been well covered scientifically. 

Dry chemistry systems are very widely used in physician s offices, hospital laboratories and many homes worldwide. They are used for routine urinalysis, blood chemistry determinations, immunolomcal and microbiolo cal testing. Today dry chemistry systems are also used mr assays in applications ranging from chlorine in swimming pools to coolant levds in cars and trucks 12). 

Lithium Hypochlorite. Lithium hypochlorite [13840-33-0], LiOCl, is obtained from reaction of chlorine and an aqueous solution of lithium hydroxide. The soHd is usually obtained as a dry stable product containing other alkaH haHdes and sulfates (64). A product containing 35% available chlorine is used for sanitizing appHcations in swimming pools and in food preparation areas where its rapid and complete dissolution is important. The salt can also be obtained in higher purity by reaction of lithium hydroxide and hypochlorous acid (65). 

Table 1. Chlorine Sanitizers Used in Swimming Pools...

Urea (24), amino acids (25), and creatinine (26) are also decomposed during superchlorination or shock treatment, with formation of N2 and other oxidation products. However, the process is slower than with ammonium ion (see Chloramines and BROMAMINEs). Urea is the principal nitrogen-containing compound in swimming pools. Since it is an amide, it reacts slowly with chlorine, yielding N2, NCl, and NO/ (27). 

Sta.bilizers. Cyanuric acid is used to stabilize available chlorine derived from chlorine gas, hypochlorites or chloroisocyanurates against decomposition by sunlight. Cyanuric acid and its chlorinated derivatives form a complex ionic and hydrolytic equilibrium system consisting of ten isocyanurate species. The 12 isocyanurate equilibrium constants have been determined by potentiometric and spectrophotometric techniques (30). Other measurements of two of the equilibrium constants important in swimming-pool water report significantly different and/or less precise results than the above study (41—43). A critical review of these measurements is given in Reference 44. 

Toxicity of Chlorine Sanitizers. Chlorine-based swimming-pool and spa and hot-tub sanitizers irritate eyes, skin, and mucous membranes and must be handled with extreme care. The toxicities are as follows for chlorine gas, TLV = 1 ppm acute inhalation LC q = 137 ppm for 1 h (mouse) (75). The acute oral LD q (rats) for the Hquid and soHd chlorine sanitizers are NaOCl (100% basis) 8.9 g/kg (76), 65% Ca(OCl)2 850 mg/kg, sodium dichloroisocyanurate dihydrate 735 mg/kg, and trichloroisocyanuric acid 490 mg/kg. Cyanuric acid is essentially nontoxic based on an oral LD q > 20 g/kg in rabbits. Although, it is mildly irritating to the eye, it is not a skin irritant. A review of the toxicological studies on cyanuric acid and its chlorinated derivatives is given in ref. 77. 

In swimming pools disinfected by bromine, bromamide and bromimide can form. These compounds have about half the disinfecting power of HOBr giving bromine an advantage compared to chlorine. Chloramide and cblorimide have 80 to 100 times less disinfecting power than HOCl. Bromides. 

Stable A/-chloro compounds are formed by reaction of hypochlorous acid and appropriate N—H compounds. For example, HOCl, formed in situ via chlorine hydrolysis, converts di- or trisodium cyanurates to dichloro- and trichloroiso-cyanuric acids, respectively (114). Chloroisocyanurates can also be prepared from isocyanuric acid or monosodium cyanurate and preformed HOCl (115—117). Hydrolysis of chloroisocyanurates provide HOCl for use in swimming pool disinfection and in bleaching appHcations. 

Acute toxicides (LD q rats) for CA and chloroisocyanurates are CA > 5.0, SDCC 1.67, PDCC 1.22, and TCCA 0.75 (126). A review of toxicological studies on CA and its chlorinated derivatives is given in Reference 127. These studies show that the compounds are safe for use in swimming pool and spa/hot tub disinfection, sanitizing, and bleaching appHcations when handled and used as directed. 

Most of the CA produced commercially is chlorinated to produce SDCC, SDCC-H, PDCC, TCCA, and the double salt TCCA4PDCC. These have become standard ingredients in formulations for scouring powders, household bleaches, institutional and industrial cleansers, automatic dishwasher compounds, and general sanitizers, and most importantly, in swimming pool and spa/hot tub disinfection. The choice of chloroisocyanurate for any particular... 

Chlorine is commonly used as a germicide in swimming pools. When chlorine dissolves in water, it reacts to form hypochlorous acid, HOC1, as follows ... 

Calcium hypochlorite is the main ingredient in swimming pool chlorine tablets. 

The results of recent trials conducted at the Cranfield University pilot-scale swimming pool are also presented. This research is based largely on chlorination using hypochlorite, but includes other technologies. Results give a clear indication of the extent to which chlorinated byproducts within the swimming pool, as well as the relative levels of DBPs formed between bromination and chlorination. The implications of this research on the future of the use of chemical biocides in swimming pools is considered. 

Fi-Clor 60S , Brochure NH/FS/67.4, Loughborough, Fisons, 1967 This compound (sodium dichloroisocyanurate), used in chlorination of swimming pools, is a powerful oxidant and indiscriminate contact with combustible materials must be avoided. Ammonium salts and other nitrogenous materials are incompatible in formulated products. The dibromo analogue, used for the same purpose, will behave similarly. 

This compound, used in chlorination of swimming pools, is a powerful oxidant, and indiscriminate contact with combustible materials must be avoided. The tribromo analogue would be similar. 

Chlorine compounds are found all around the home. On the table is sodium chloride, ordinary table salt. In the kitchen and bath are chlorine scouring powders, and chlorine bleach is used in the laundry. Chlorine is used as a disinfectant in swimming pools, and in industry it is used to make paper. 

In addition to drinking water, chlorinated oxidants reacting with organic materials will lead to the formation of chloroform in swimming pools. Since swimming pools are not routinely analyzed for their chloroform content, data are limited and derived from special studies. Such studies will often cover the broader family of THMs, and while chloroform levels in blood or alveolar air samples will be reported, the environmental agents will often simply be recorded in terms of THMs. A rule of thumb (Copaken 1990) is... 

Chlorine s best-known characteristic is its smell. It can be detected when used as household bleach or as an antiseptic in swimming pools. As an antiseptic, it is added to municipal drinking water supplies. Chlorine gas has a very pungent odor that is suffocating when inhaled. In a more concentrated form, Cl was also a deadly poisonous gas used in combat during World War I. Because it combines with so many other elements, particularly metals, chlorine is fundamental to many industries, particularly the plastics industry. 

Terasaki M, Makino M (2008) Determination of chlorinated by-products of parabens in swimming pool water. Int J Environ Anal Chem 88(13) 911-922... 

Li J, Blatchley ER III (2007) Volatile disinfection byproduct formation resulting from chlorination of organic - Nitrogen precursors in swimming pools. Environ Sci Technol 41 (19) 6732-6739... 

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