Presence Of Potassium Bromide Research Articles

Rheological behaviour of wormlike micelles : effect of salt content

We study the effect of salt content on the rheological properties of wormlike micelles formed from hexadecyltrimethylammonium bromide (CTAB) in presence of potassium bromide (KBr) and of cetylpyridinium chlorate (CPClO 3 ) in presence of sodium chlorate (ClO 3 Na). Upon increasing the salt concentration, at fixed surfactant concentration, we observe for both systems a maximum of the zero-shear viscosity η 0 . For salt concentrations less than that corresponding to the maximum of η 0 , the variation of η 0 with the surfactant concentration C can be described by a reptation model. Beyond the maximum, the scing laws obtained for η 0 (C) are characterized by values of the exponent much smaller than those predicted by the existing theoretical models. The results are qualitatively interpreted by a description based on a structural evolution upon increasing salt content from a system of entangled linear micelles to a multiconnected network. Measurements of the plateau modulus of CTAB solutions, as a function of KBr, give results supporting the above hypothesis

Temperature dependence of the non-Newtonian viscosity of elongated micellar solutions

We report in this work new results of the study on the non-Newtonian viscosity of aqueous micellar solutions of cetyltrimethylammonium bromide (CTAB) in the presence of potassium bromide (KBr), in the concentration range where the elongated micelles overlap. The experiments have been performed as a function of the surfactant concentration, temperature and shear rate by use of a Couette-viscosimeter. In the non-Newtonian range, at relatively low surfactant concentration (≲0.25 M/l), our results show that the flow curves obtained at different temperatures converge to a single liner curve with a characteristic slope varying with the surfactant concentration. These same data can be superposed on a master curve when appropriate reduced variables are used. The shape of the flow curves obtained at different temperatures for a sufficiently high surfactant concentration is similar to that obtained for monodisperse polymer solutions at different molecular weights. The slope obtained of about −1 is also predicted by Graessley's model in the theory of microviscoelasticity based on the concept of entanglement for polymer solutions. However, at surfactant concentration higher than 0.25 M/l our results show an unusual behavior. Above some critical shear rate it is possible to obtain an increase of the apparent viscosity with temperature. One possible explanation of this effect can be found in the increase of the entanglement with concentration coupled with the temperature and direct now effects on scission and recombination rate of the micelles.

Rheological properties of semidilute and concentrated aqueous solutions of cetyltrimethylammonium bromide in the presence of potassium bromide

Les proprietes rheologiques des solutions aqueuses de bromure de cetyltrimethylammonium en presence de 0,25 M de KBr, sont bien en accord avec le modele de Cates qui prend en compte la variation de la dimension des micelles

Poly(pyrrolium tosylate) formation on a mercury anode in the presence of halide ions

Abstract A study of poly(pyrrolium tosylate) by cyclic voltammetry in the presence of bromide and chloride ions has facilitated the determination of the oxidation potential of pyrrole on mercury. Elemental analysis and scanning electron microscope examination of a large film produced in the presence of potassium bromide indicate that any mercury formed by the anodic oxidation is removed as crystalline mercurous bromide, while about one-eighth of the tosylate dopant is replaced by bromide ions.

Rheological properties of semidilute and concentrated aqueous solutions of cetyltrimethylammonium bromide in the presence of potassium bromide

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRheological properties of semidilute and concentrated aqueous solutions of cetyltrimethylammonium bromide in the presence of potassium bromideS. J. Candau, E. Hirsch, R. Zana, and M. DelsantiCite this: Langmuir 1989, 5, 5, 1225–1229Publication Date (Print):September 1, 1989Publication History Published online1 May 2002Published inissue 1 September 1989https://doi.org/10.1021/la00089a018RIGHTS & PERMISSIONSArticle Views410Altmetric-Citations116LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (529 KB) Get e-Alerts Get e-Alerts

Determination of nitrite and mixtures of bromide and iodide with o-iodosobenzoate

Nitrite diazotizes sulphanilamide, which then does not undergo 3,5-dibromination. Nitrite can therefore be determined by reaction with excess of sulphanilamide, the surplus of which is then titrated with o-iodosobenzoate or chloramine-T in the presence of potassium bromide, with Methyl Red as indicator. Mixtures of iodide and bromide can be analysed by oxidation of the iodide with excess of o-iodosobenzoate at pH 4–6, followed by extraction of the iodine (which is then titrated with thiosulphate) and then oxidation of the bromide in dilute sulphuric acid medium in the presence of sulphanilamide as bromine scavenger, the residual oxidant being evaluated iodometrically.

Indirect flow injection voltammetric determination of aromatic amines by monitoring at a glassy carbon electrode the excess of nitrite remaining after their diazotisation

Excess of nitrite, after reaction with aniline, sulphanilic acid or sulphanil-amide in the presence of potassium bromide, is determined by flow injection voltammetry at a glassy carbon electrode by injection of the reaction mixture into 0.3 M hydrochloric acid. The reaction is stoicheiometric but the amperometric signal is not directly proportional to the amine concentration. For the determination of these amines (1 × 10–6–1 × 10–4M) the use of a 10–90% excess of nitrite is recommended. The amines have also been determined by direct injection of amine (1 × 10–8–1 × 10–4M) in 3.2 M hydrochloric acid into a neutral eluent 1 × 10–4, 1 × 10–5 or 1 × 10–6M in nitrite and 20%m/V in potassium bromide. The reaction was incomplete in this direct injection but good reproducibility was obtained.

Reaction of Camphene with Chloroacetic Acid and the Synthesis of 2-(8-Camphenyl)ethanol

Abstract Camphene (1) reacts with chloroacetic acid (2) or its polymer, polyacetoxamer; α-chloro, ω-carboxy in the presence of potassium bromide at reflux temperature to give the 2,2-dimethyl-exo-3-hydroxynorbornane-endo-3-propanoic acid lactone and the 2,2-dimethyl-endo-3-hydroxynorbornane-exo-3-propanoic acid lactone in a 50% yield. The synthesis of 2-(8-camphenyl)ethanol from 1 was simplified by utilizing this reaction.

Determination of cyanide by oxidation to nitrite

It has been found that cyanide in an alkaline solution is quantitatively oxidized to nitrite by hypochlorite in the presence of potassium bromide, and the nitrite produced is determined spectrophotometrically with sulfanilamide and N-1-naphthylethylenediamine reagents. It was applied to a determination of cyanide, and the conditions for determination were investigated. The procedure established is as follows.To 20ml of a sample solution are added 1ml of 0.5M sodium hydroxide solution, 2ml of 0.75% potassium bromide solution and 1ml of sodium hypochlorite solution cotaining 0.2% active chlorine. The solution is allowed to stand for 6hrs. in boiling water, and transferred to a 50ml volumetric flask after cooling. By adding 1ml of 4% arsenic trioxide in 1M sodium hydroxide to the solution, the excess hypochlorite is completely decomposed. Two milliliters of 1% sulfanilamide in 1.2M hydrochloric acid and then, after 28min, 1ml of 0.1% N-1-naphthylethylenediamine solution are added and the whole is diluted to the mark with water. After 10min, the absorbance is measured at 543mμ with a 1-cm cell against the reagent blank. The sensitivity of this method is onehalf of the pyridine-pyrazolone method.

Intermediate steps in autoxidation: III. Reactions of Mn III acetate in acetic acid with benzene, chlorobenzene, and toluene

Product data on the reactions of manganic acetate in glacial acetic acid with benzene (100 °C), chlorobenzene, or toluene (110 °C) indicate that HOOCCH 2· radicals are the primary intermediates. Presumably, these are formed from manganic acetate and acetic acid in a concerted step. In the absence of benzene derivatives, they react with manganic acetate to form acetoxyacetic acid or dimerize to succinic acid; acetoxyacetic acid is further degraded to methylene diacetate. Benzene, chlorobenzene, or toluene add on HOOCCH 2· radicals, forming phenylacetic acid(s); these in turn are further degraded to benzyl acetate(s), benzal diacetate(s) and benzaldehyde(s) which are the main products, accounting for more than 60% of the oxidizing agent. In the presence of potassium bromide, toluene reacts at a much higher rate; products then are mainly benzyl acetate and benzyl bromide. Rates of reduction of Mn III acetate in the presence of manganous acetate are not affected by large proportions of benzene or chlorobenzene; toluene has a slight accelerating effect. Products and mechanisms are compared with those obtaining in oxidations by manganic acetate in which electron transfer is the primary step.

Determination of formic acid by catalytic oxidation with cerium(IV)

A method is proposed for the determination of formic acid by oxidation with cerium(lV) in presence of potassium bromide. The method can also be used for the further oxidation of organic compounds which yield formic acid under ordinary conditions with cerium(IV).

Viscometric behavior of polyacrylate ion in concentrated salt solutions

AbstractViscosities of polyacrylate ion in the presence of potassium bromide, sodium bromide, lithium bromide, sodium iodide, sodium hydroxide, and hydrochloride acid in aqueous solution were measured over the approximate ranges 0.0–0.6% polymer and salt up to saturation with respect to polyacrylate or to salt. The general initial effect of added electrolyte is to reduce the ratio ηsp/c and to convert the curve characteristic of polyelectrolytes into a straight line, which can be extrapolated to zero polymer concentration to given [η], the intrinsic viscosity of the polymer in the presence of excess salt. Sodium hydroxide and sodium bromide produce minima in plots of [η] against salt concentration. Sodium iodide precipitates polyacrylate at 1.5 N iodide as a translucent gel, which redissolves at 3.0 N and finally reprecipitates at 6 N. In the latter range of concentration, [η] exhibits a maximum. Both by‐ions and counter‐ions have specific effects on the viscosity of the polyion.

On the Incompatibility of Chloral Hydrate in the Presence of Potassium Bromide and Alcohol

On the Incompatibility of Chloral Hydrate in the Presence of Potassium Bromide and Alcohol

On the Incompatibility of Chloral Hydrate in the Presence of Potassium Bromide and Alcohol

On the Incompatibility of Chloral Hydrate in the Presence of Potassium Bromide and Alcohol