Chlorine, in tap water

CL sensors based on immobilization of nonenzyme reagents have been extensively studied in recent years. Nakagama et al. [63] developed a CL sensor for monitoring free chlorine in tap water. This sensor consisted of a Pyrex tube, packed with the uranine (fluoresceine disodium) complex immobilized on IRA-93 anion-exchange resin, and a PMT placed close to the Pyrex tube. It was used for monitoring the concentration of free chlorine (as HCIO) in tap water, up to 1 mmol/L, with a detection limit of 2 nmol/L. The coefficient of variation (n =... 

Tap water is undoubtedly convenient it is clean, usually available whenever you want it, and supplied at high pressure. The provision of this service, however, may come at an unnecessary cost—both financial and environmental. The chlorine in tap water may harm your soil s microbe population and damage sensitive plants. Tap water may also have a high pH (see pp.30-31), making it unsuitable for use on lime-hating plants. 

This thin-film-composite membrane has been found to have appreciable resistance to degradation by chlorine in the feed-water. Figure 2 illustrates the effect of chlorine in tap water at different pH values. Chlorine (100 ppm) was added to the tap water in the form of sodium hypochlorite (two equivalents of hypochlorite ion per stated equivalent of chlorine). Membrane exposure to chlorine was by the so-called "static" method, in which membrane specimens were immersed in the aqueous media inside closed, dark glass jars for known periods. Specimens were then removed and tested in a reverse osmosis loop under seawater test conditions. At alkaline pH values, the FT-30 membrane showed effects of chlorine attack within four to five days. In acidic solutions (pH 1 and 5), chlorine attack was far slower. Only a one to two percent decline in salt rejection was noted, for example, after 20 days exposure to 100 ppm chlorine in water at pH 5. The FT-30 tests at pH 1 were necessarily terminated after the fourth day of exposure because the microporous polysul-fone substrate had itself become totally embrittled by chlorine attack. 

Chlorine in air can be determined by passing air through an alkaline solution of 4-nitroaniline and measuring the absorbance of the compound formed (e= 1.9-10 at 485 nm) [16]. Chlorine in tap-water has been determined by adding phenolphthalein (in the reduced form) and ferrocyanide. The ferricyanide ions formed produce an equivalent amount of red phenolphthalein (in alkaline medium) [17]. 

A sensitive method for determining chlorine in tap water has been based on the reaction of chlorine with thio-Michler s ketone (formula 46.2) (e = 7.7T0 at 640 nm). The method has been applied in the FIA technique [65]. The reaction of chlorine with 4-nitroaniline has been applied in the continuous method of determining chlorine in air [66]. 

Prohexadione-calcium at the level of 0.08 mg kg in tap water degrades and disappears rapidly. Degradation of prohexadione-calcium can be prevented by addition of ascorbic acid at about 1 mg kg in tap water. Degradation products of prohexadione-calcium by aqueous chlorination are identified by mass spectrometry. 

Shiraishi, H., N.H. Pilkington, A. Otuski, and K. Fuwa. 1985. Occurrence of chlorinated polynuclear aromatic hydrocarbons in tap water. Environ. Sci. Technol. 19 585-590. 

Mature, oocyte positive, female Xenopus laevis are kept in (mesh) covered grey plastic tanks in tap water (depth 15-20 cm, 3-4 L per animal) at 16-19°C under constant light regime (12-h day/night cycle). The quality of the tap water should be tested at the beginning and care should be taken on the chlorine and heavy metal content. A simple way to eliminate excessive chlorine from the water is storage of the water for 24 h. Clay tubes in the tanks allow the frogs to cover themselves. The animals are fed a commercially available pellet diet twice a week, and occasionally they receive small pieces of bovine heart. The tanks have to be cleaned after each meal. 

Chemical/Physical. It was suggested that the chlorination of dibenzofuran in tap water accounted for the presence of chlorodibenzofuran (Shiraishi et al., 1985). 

Chemical/Physical. Oxidation by ozone to fluorenone has been reported (Nikolaou, 1984). Chlorination of fluorene in polluted humus poor lake water gave a chlorinated derivative tentatively identified as 2-chlorofluorene (Johnsen et al., 1989). This compound was also identified as a chlorination product of fluorene at low pH (<4) (Oyler et al, 1983). It was suggested that the chlorination of fluorene in tap water accounted for the presence of chlorofluorene (Shiraishi et al., 1985). 

It was suggested that the chlorination of naphthalene in tap water accounted for the presence of chloro- and dichloronaphthalenes (Shiraishi et ah, 1985). Kanno et al. (1982) studied the aqueous reaction of naphthalene and other aromatic hydrocarbons (benzene, toluene, o-, m-, and p-xylene) 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 increased at lower pHs (Kanno et ah, 1982). 

Kronberg L, Vartiainen T (1988) Ames mutagenicity and concentration of the strong mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone and of its geometric isomer E-2-chloro-3-(dichloromethyl)-4-oxo-butenoic acid in chlorine-treated tap waters. Mutat Res 206 177-182... 

Because chlorine dioxide is a very reactive chemical, it is able to kill bacteria and microorganisms in water. About 5% of large water treatment facilities (serving more than 100,000 people) in the United States use chlorine dioxide to treat drinking water. It is estimated that about 12 million people may be exposed in this way to chlorine dioxide and chlorite ions. In communities that use chlorine dioxide to treat water for drinking uses, chlorine dioxide and its by-product, chlorite ions, may be present at low levels in tap water. 

In a 12-week epidemiological study conducted in a small town in Ohio, the ranges of concentrations of chlorine dioxide, chlorite ion, and chlorate ion in drinking water were 0.3-1.1, 3.2-7.0, and 0.3-1.1 mg/L, respectively (Lykins et al. 1990 Michael et al. 1981). In one study using a sensitive analytical method, the average concentration of chlorine dioxide in tap water from the city of Brest, France was 1.8x10 mol/L (0.012 mg/L) (Quentel et al. 1994). 

Quentel F, Elleouet C, Madec C. 1994. Electrochemical determination of low levels of residual chlorine dioxide in tap water. Anal Chim Acta 295 85-91. 

All water used in the procedure should be distilled or deionized water or chlorine-free tap water. 

When free chlorine is determined in tap water, a sample of water is placed in a still (with no oxidizer) and chlorine is distilled, along with some water, into a reeeiver containing Methyl Red. The sample water may also be added directly to a Methyl Red solution. 

LSD is an unusualy fragile molecule... As a salt, in water, cold, and free from air and light exposure, its is stable indefinitely... Oh yes, and often overlooked, there may be only an infinitesimal amount of chlorine in treated tap water, but then there is only an infinitesimal amount of LSD in a typical LSD solution. And since chlorine will destroy LSD on contact, the dissolving of LSD in tap water is not appropriate, Shulgin in TIHKAL. 

In solution, HOCl and hypochlorite concentrations are commonly determined together by standard water analysis methods (AWWA, 1989). The sum of their concentrations is referred to as free available chlorine and is usually reported in parts per million (1 ppm free available chlorine = 1.4x 10" M). Detectable levels of free and combined (nitrogenous) available chlorine in treated water constitute a chlorine residual. In normal practice in North America, water utilities attempt to adjust chlorination levels to a small chlorine residual (2x 10" M or less) that is sufficient to survive throughout the drinking water distribution system all the way to the user s water taps. To achieve this level in the distribution lines, it may be necessary to add as much as 10 times higher amounts to the water in the plant, depending on the amount of reactive material in the source water and in the lines. 

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