Bromide concentration

Bromide ndIodide. The spectrophotometric determination of trace bromide concentration is based on the bromide catalysis of iodine oxidation to iodate by permanganate in acidic solution. Iodide can also be measured spectrophotometricaHy by selective oxidation to iodine by potassium peroxymonosulfate (KHSO ). The iodine reacts with colorless leucocrystal violet to produce the highly colored leucocrystal violet dye. Greater than 200 mg/L of chloride interferes with the color development. Trace concentrations of iodide are determined by its abiUty to cataly2e ceric ion reduction by arsenous acid. The reduction reaction is stopped at a specific time by the addition of ferrous ammonium sulfate. The ferrous ion is oxidi2ed to ferric ion, which then reacts with thiocyanate to produce a deep red complex. 

The approximate composition of surface water in the Dead Sea in 1966 (49) was given as 35 g/L calcium chloride 130 g/L magnesium chloride nearly 80 g/L sodium chloride more than 10 g/L potassium chloride nearly 4 g/L bromide and about 1 g/L sulfate. At 400 m depth the bromide concentration was 6 g/L. Bromine in Israel is produced from the Hquors left from potash production and the bromide content of these Hquors is 14 g/L. 

Fig. 19.41 Dependence of breakdown potential of Fe-Cr alloys (containing 13% Cr, in 0-1 mol dm HBr + Kj SO4 solution) on the ratio of sulphate and bromide concentration in...

Subsequently, rate coefficients were determined for the zinc chloride-catalysed bromination of benzene, toluene, i-propyl-benzene, r-butylbenzene, xylenes, p-di-f-butylbenzene, mesitylene, 1,2,4-trimethyl-, sym-triethyl-, sym-tri-f-butyl-, 1,2,3,5-and 1,2,4,5-tetramethyl- and pentamethylbenzenes, all at 25.4 °C and in acetic acid, and it was shown that the reaction was inhibited by HBr.ZnCl2 which accumulates during the bromination and was considered to cause the first step of the reaction (formation of ArHBr2) to reverse320. The second-order coefficients for bromination of o-xylene at 25.0 °C were shown to be inversely dependent upon the hydrogen bromide concentration and the reversal of equilibrium (155)... 

To demonstrate that a group of alkyl bromides could be derivatized at low alkyl bromide concentration, a similar experiment... 

The oxidation by Mn(Iir) in a perchlorate medium follows two kinetic paths depending on the bromide concentration, viz. 

OS 59] ]R 34] ]P 42] Conversion was monitored versus cell voltage for four bromide concentrations, 5, 20, 100 and 200 mM NaBr (150 pi min ) [71]. Whereas a 50% conversion was achieved for the lowest salt content, the two highest concentrations led to 70% conversion. When the 5 and 100 mM operations were compared for the same conversion (70%), the energy consumption and the current efhdency were much worse when using the higher salt concentration (50 mM furan ... 

Same as for pyridinium hydrotribromide Used in place of bromine when low bromide concentration is required. 

A model calculation showed that the HiPOx system may have been fully successful in limiting bromate formation under the chosen oxidant doses if the influent bromide concentration was 0.56 mg/L or less. Since a bromide concentration of 0.56 mg/L is still extremely high for a drinking water source, the HiPOx system appears to hold promise for destroying MTBE and its oxidative by-product TBA while controlling bromate formation, even in waters that have high bromide concentrations.101... 

Solutions of TKPP were mixed with aqueous fluids commonly encountered in drilling or completion of wells. Unlike saturated zinc bromide, concentrated TKPP solutions can be mixed in any proportion with fresh water with the only result being a decrease in solution density. Similar results were obtained with conventional oil field brines containing as much as 400 parts per million polyvalent cations, mostly calcium. Saturated solutions of calcium hydroxide also can be added to TKPP in any proportion without promoting precipitation as can concentrated hydrochloric acid solutions, conventionally used for well stimulation. The acid tends to generate a slight haze as the pH is reduced from 11.5 to approximately 8 however, this haze rapidly disappears as the pH is lowered by further addition of acid. 

Empirical relationships (5) between the experimental rate constants and the k-values extrapolated to zero bromide concentrations have been... 

A preliminary indication that bromonium ions could be formed reversibly was provided by the reaction of adamantylideneadamantane (p. 249) leading to a highly stable bromonium-tribromide ion pair that readily releases bromine and the initial alkene (Strating et al, 1969). However, the first evidence for possible return came from the acetolysis of 2-bromocyclohexyl-brosylate in the presence of bromide ions. It was shown (Brown et al, 1984) that the cyclohexylbromonium ion intermediate is able to release bromine. The drastic reaction conditions (high temperature, long duration and high bromide concentrations) cast some doubt on the generality of this observation. 

For homopolyelectrolyte, we first studied the ellipsometric measurement of the adsorption of sodium poly(acrylate) onto a platinum plate as a function of added sodium bromide concentration (5). We measured the effect of electrolyte on the thickness of the adsorbed layer and the adsorbances of the polyelectrolyte. It was assumed that the Donnan equilibrium existed between the adsorbed layer and the bulk phase. The thickness was larger and the adsorbance of the polyelectrolyte was lower for the lower salt concentration. However, the data on the molecular weight dependence of both the adsorbance and the thickness of the adsorbed polyelectrolyte have been lacking compared with the studies of adsorption of nonionic polymers onto metal surfaces (6-9). 

In the addition reaction the second molecule of Grignard reagent may be replaced by a molecule of magnesium bromide, and for this reason it is possible, by increasing the magnesium bromide concentration, to double the amount of addition at the expense of the... 

The disadvantage of the hypochlorite recycling process is the small increase of chlorate and bromide concentrations in the cell-liquor. However, this is offset by higher chlorine production (0.1% more), resulting in a higher current efficiency. 

The enhancement of SWV net peak current caused by the reactant adsorption on the working electrode surface was utilized for detection of chloride, bromide and iodide induced adsorption of bismuth(III), cadmium(II) and lead(II) ions on mercury electrodes [236-243]. An example is shown in Fig. 3.13. The SWV net peak currents of lead(II) ions in bromide media are enhanced in the range of bromide concentrations in which the nentral complex PbBr2 is formed in the solntion [239]. If the simple electrode reaction is electrochemically reversible, the net peak cnnent is independent of the composition of supporting electrolyte. So, its enhancement is an indication that one of the complex species is adsorbed at the electrode snrface. 

Chlorination of waters containing two phenylurea-type herbicides, isoproturon and diuron, results in the formation of THMs. The reaction of the phenylurea-type herbicide isoproturon with chlorine produced compounds that still contained the aromatic ring of the herbicide with the urea side-chain unmodified. The formation of chlorinated and brominated derivatives was related to the bromide concentration present in the water [113]. 

Fig. 12.6 (A) Calculated (solid curves) and measured (points) mean bromide concentrations, normalized by the mass of appUed solute per unit soil surface, at times r = 18 and 32 days (B) Mean bromacd concentrations, normalized by the mass of apphed solute per unit soU surface, at times r = 18 and 32 days (solid curves best-fit based on least squares of differences between computed and measured mean concentrations, = 0.14 mL/g, X = 0.022dashed curves based on sum of squares of differences, = 0.16 mL/g, day X = 0.012 daysdotted-dashed curves ...

Wingenter, O. W., C. J.-L. Wang, D. R. Blake, and F. S. Rowland, Seasonal Variation of Tropospheric Methyl Bromide Concentrations Constraints on Anthropogenic Input, Geophys. Res. Lett., 25, 2797-2800 (1998). 

Consequently, all the data in Figure 2 can be explained in terms of the different reactivities of the various aggregates. The insensitivity of the rate of thiocyanate entry to the thiocyanate concentration simply shows that, over the whole concentration range studied, the substrate was always in the form of the ion triplet. The rate dependence on the chloride or bromide concentration represents the change in the distribution of the substrate between the 2 1 and the 3 1 aggregate as the anion concentration is increased. 

Figure 1.11 Adiabatic conversion of nylon 6 Experimental data for initial polymerization temperatures of 117°C (bottom line), 136°C (middle line), and 157°C (top line) with acyllactam and caprolactam-magnesium-bromide concentrations of 70 and 108mmol/L, respectively...

Method 3-4 is an improvement over the method of making bromopropadiene by shaking 3-bromopropyne for 6 days with cuprous bromide, concentrated hydrochloric acid, ammonium bromide, and copper bronze to afford a 28 % yield of bromopropadiene. 

Bromine is a dense, red, volatile, corrosive liquid (bp 59 °C) that is best made by oxidizing the small amount of Br in seawater with chlorine (higher bromide concentrations occur in the Dead Sea and in certain natural brines, e.g., in Arkansas and Michigan). The vapor of the resulting Br2 is then carried off in an air stream ... 

Limited information was located regarding distribution of PBBs in animals after inhalation exposure. Increased bromide concentrations were observed in the liver and adipose tissue of rats exposed continuously to vapors of a commercial octabromobiphenyl mixture (33% octa, 60% nona, 6% deca, 1% hepta) (3.5 pg octabromobiphenyl/L air at equilibrium) for 15 weeks (Waritz et al. 1977). Relative to controls, the concentration of bromide in liver and fat was increased by 39 and 100%, respectively bromide concentration in skeletal muscle was not affected by treatment. No further details were provided. 

After absorption, methyl bromide or metabolites are rapidly distributed to many tissues including the lung, adrenal gland, kidney, liver, nasal turbinates, brain, testis and adipose tissue. In an inhalation study in rats, the methyl bromide concentrations in tissues reached a maximum after 1 h of exposure, but decreased rapidly. Methyl bromide is probably metabolized by glutathione conjugation, the fonned. S -mcthylglutathione being sequentially catabolized to. S -methyl-L-cystcinc and then to carbon dioxide. 

Figure 1. Fraction of lithium bromide existing as free ions in Solvents I-IV as a function of lithium bromide concentration...

Figure 4. Corrected specific conductance of lithium bromide as a function of lithium bromide concentration for Series I-IV...

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