Hypochlorite analysis

Commercial bleaching solutions found on store shelves are usually labeled Contains at least 5.25% sodium hypochlorite. Analysis will often show a lower OCL ion content. Briefly explain. 

Arsenic trioxide may be made by burning arsenic in air or by the hydrolysis of an arsenic trihaUde. Commercially, it is obtained by roasting arsenopyrite [1303-18-0] FeAsS. It dissolves in water to a slight extent (1.7 g/100 g water at 25°C) to form a weaMy acidic solution which probably contains the species H AsO, orthoarsenous acid [36465-76-6]. The oxide is amphoteric and hence soluble in acids and bases. It is frequendy used as a primary analytical standard in oxidimetry because it is readily attainable in a high state of purity and is quantitatively oxidized by many reagents commonly used in volumetric analysis, eg, dichromate, nitric acid, hypochlorite, and inon(III). 

The amount of sodium hypochlorite in a bleach solution can be determined by using a given volume of bleach to oxidize excess iodide ion to iodine CIO- is reduced to Cl-. The amount of iodine produced by the redox reaction is determined by titration with sodium thiosulfate, Na2S203 I2 is reduced to I-. The sodium thiosulfate is oxidized to sodium tetrathionate, Na2S406. In this analysis, potassium iodide was added in excess to 5.00 ml of bleach d = 1.00 g/cm3). If 25.00 mL of 0.0700 MNa2S203 was required to reduce all the iodine produced by the bleach back to iodide, what is the mass percent of NaCIO in the bleach ... 

Acridine-9-carbaldehyde (24%) is one of several products formed from the oxidation of 5//-dibenz[A/]azepine with tert-butyl hypochlorite in dichloromethane at — 70 C.229 The reaction is even more complex in the presence of silver(I) trifluoroacetate, and an analysis of the reaction mixture by GC-MS techniques reveals the presence of eleven products, the major ones being acridine (37%), an unidentified 5//-dibenz[/ ,/]azepinecarbaldehyde (23%) and acridine-9-carbaldehyde (9 %). 

After completing our analysis of the effects of the dominant equilibrium, we may need to consider the effects of other equilibria. The calculation of [H3 O ] in a solution of weak base illustrates circumstances where this secondary consideration is necessary. Here, the dominant equilibrium does not include the species, H3 O, whose concentration we wish to know. In such cases, we must turn to an equilibrium expression that has the species of interest as a product. The reactants should be species that are involved in the dominant equilibrium, because the concentrations of these species are determined by the dominant equilibrium. We can use these concentrations as the initial concentrations for our calculations based on secondary equilibria. Look again at Example for another application of this idea. In that example, the dominant equilibrium is the reaction between hypochlorite anions and water molecules H2 0 l) + OCr(c2 q) HOCl((2 q) + OH ((2 q) Working with this equilibrium, we can determine the concentrations of OCl, HOCl, and OH. To find the concentration of hydronium ions, however, we must invoke a second equilibrium, the water equilibrium 2 H2 0(/) H3 O (a q) + OH (a q)... 

Fig. Ja-c. Sensitivity analysis on the effect of P(3HB) content and nrodurtivitv disest[tl0n P(3HBj f diferent yieid 311(1 Production scale. Surfactant-hypochlorite sion) "l h0d Sed f°r Ae reC°Very °f P(3HB> ("Produced from [29] with permis-...

The reaction has been studied kinetically, and it is found that when a solid catalyst (CoO and/or Co203) formed by adding Co(N03)2 to a solution of NaOCl is present, the rate of the reaction is determined by the surface area of the catalyst. Hypobromites and hypoiodites are good oxidizing agents, though less commonly used than hypochlorites. One use of NaOBr is in analysis where it is used to oxidize urea and NH4+ to produce N2. 

Emmet [301] developed a colorimetric method involving chlorination of the urea with hypochlorite, followed by condensation with phenol. The limit of detection for this method was 0.2 p,g/l as nitrogen. The method was easily adaptable to automatic analysis. 

For analysis in solutions, the most frequently used CL reaction is alkaline oxidation of luminol and lucigenin in the presence of hydrogen peroxide as oxidant, although sodium hypochlorite, sodium perborate, or potassium ferricyanide may also be used. CL reactions involving alkaline oxidation have been used to indicate acid-base, precipitation, redox, or complexometric titration endpoints either by the appearance or the quenching of CL when an excess of titrant is present [114, 134], An example of these mechanisms is shown in Figure 14. 

The flow-cell design was introduced by Stieg and Nieman [166] in 1978 for analytical uses of CL. Burguera and Townshend [167] used the CL emission produced by the oxidation of alkylamines by benzoyl peroxide to determine aliphatic secondary and tertiary amines in chloroform or acetone. They tested various coiled flow cells for monitoring the CL emission produced by the cobalt-catalyzed oxidation of luminol by hydrogen peroxide and the fluorescein-sensitized oxidation of sulfide by sodium hypochlorite [168], Rule and Seitz [169] reported one of the first applications of flow injection analysis (FTA) in the CL detection of peroxide with luminol in the presence of a copper ion catalyst. They... 

It was found that the concentration of total oxidants measured in the off-gas from the hypo unit varied with process conditions. Precise analysis of the off-gas showed that under certain conditions chlorine dioxide is formed in the reaction step where the hypochlorite concentration is approximately 160-180 g l-1. In the sections below formation of chlorine dioxide in the hypochlorite unit is discussed with regard to process conditions and peak load of the feed stream. In essence, the emission of chlorine dioxide can be reduced to nearly zero by using a scrubber in which the chlorine dioxide reacts with hydrogen peroxide. 

When the reaction temperature of step one increases, the total oxidant concentration in the off-gas is >6 mg m-3, but this depends on capacity and hypochlorite concentration. Careful analysis with infrared methods demonstrated that this total oxidant concentration was derived from chlorine dioxide. Measurements of the concentrations between steps one and two showed that concentrations were higher than in the off-gas and that hypochlorous acid (HOC1) was also found, which was totally absent in the off-gas. 

Economic analysis of designs at lower natural hypochlorite strengths equally show potential investment benefits. They are, however, much less significant than the batch and high concentration cases described above. While an economic case can be made for retrofitting an in-loop reactor to a system that already has an end-of-pipe treatment system based on payback, it is not always clear that this is a better option than an end-of-pipe hybrid system as described earlier in the chapter. For a particular system the optimum solution is often as much a function of the required expenditure on the heat exchangers as it is the relative cost of the reactor options. 

Analysis of the Mechanisum of Deterlorationof Asymmetric Cellulose Acetate Membrane by Sodium Hypochlorite... 

The structure analysis of nitrites, however, shows that they contain isolated NO " groups in complexes of trivalent metals, e.g. in the alkali aluminates (KA102) that have the same bruto composition as the nitrites, the coordination, indeed, is higher. Here the AI3 ions are surrounded by six oxygen ions, a coordination number that is as to be expected for a really ionic compound. Hypochlorites ACIO, chlorites AC102, chlorates AG103, sulphites A2S03, etc., all have coordination numbers that are smaller than those to be expected in ionic compounds. 

Another concurrent factor not considered in the risk analysis was the toxicology of residual amounts of the disinfectant species including hypochlorous acid and chloramines related to chlorine that would normally be present as residuals in chlorinated water. The in vivo toxicology of hypochlorite now indicates the formation of haloforms and halonitriles and thus additional risks (34). 

Analysis When it is known that a chlorite is the only active oxidg agent present, it is easily determined by titration of the iodine liberated from KI in an acidified soln. A chlorite does not liberate iodine until the soln is acidified this serves as a qualitative distinction from a hypochlorite. The quantitative analysis of a soln contg chlorite 8c hypochlorite requires detn of the total oxidg power. Hypochlorite is detd on a separate sample by addg an excess of Na arsenite, after making certain the soln is alk. This "soln is saturated with... 

MW Dong, JR Gant. High-speed liquid chromatographic analysis of amino acids by post-column sodium hypochlorite-o-phthalaldehyde reaction. J Chromatogr 327 17-25, 1985. 

At the end of the workday it is recommended that work areas be decontaminated overnight with sodium hypochlorite and thoroughly washed and that the surfaces be checked for neutrality before starting a new analysis. 

During the analysis, a flask containing a 5% aqueous solution of sodium hypochlorite should be kept near the bench, in case of emergency. The issue of safety precautions has been studied rather extensively for aflatoxins (21), ochratoxin A, citrinin, sterigmatocystin, and pat-ulin (22). 

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