Aqueous Solutions Of Potassium Bromide Research Articles

Functionalization of Titanium Alloy Surface by Graphene Nanoplatelets and Metal Oxides: Corrosion Inhibition.

Corrosion inhibition of metallic substrates is an important and crucial step for great economical as well as environmental savings. In this paper, we introduce an extra thin effective corrosion inhibitive material having layered structure designed for protection and functionalization of Ti Grade 5 alloy substrates. The coating consists of a first layer made of thin graphene nanoplatelets, on top of which a multilayer Al2O3 and TiO2 films is applied by low-temperature atomic layer deposition. The amorphous structure of the metal oxide films was confirmed by micro-Raman and X-ray diffraction analysis. Corrosion inhibition ability of the prepared coatings was analyzed by open circuit potential, potentiodynamic plot and by voltammetric analysis, in aqueous potassium bromide solution. The open circuit potential of the graphene-metal oxide coated substrate showed much passive nature than bare substrate or graphene coated or only metal oxide coated substrates. The localized corrosion potential of the graphene-metal oxide coated, only metal oxide coated, and bare substrates were found 5.5, 3.0, and 1.1 V, respectively. In addition, corrosion current density values of the graphene-metal oxide and only metal oxide coated substrates showed much more passive nature than the bare and graphene coated substrates. Long immersion test in the salt solution further clarified the effective corrosion inhibition of the graphene-metal oxide coated substrate. The analyzed results reflect that the graphene-metal oxide films can be used to prepare better and effective corrosion inhibition coatings for the Ti Grade 5 alloy to increase their lifetime.

The kinetics of crystallization of potassium bromide from aqueous solution.

Abstract The densities of aqueous solutions of potassium bromide have been determined as a function of concentration and temperature up to saturation at temperatures between 10 and 50°. The saturation line and nucleation were studied, over the same temperature range, in a circulatory crystallizer with continuous concentration monitoring. Small quantities of seed crystals were grown under different degrees of supersaturation and at different temperatures, so that the mass transfer coefficients and the activation energy for deposition from solution could be measured. The activation energy of the crystallization process was 100·9 kJ mol−1, indicating that the rate-determining step was the incorporation of KBr on to the crystal lattice. Rapidly-grown crystals might thus be expected to be softer, and this proved to be so.

Debundling of carbon single-walled nanotubes at oxidation of bromine ions

An electrochemical method of modification of carbon single-walled nanotubes at anodic polarization in aqueous solutions of potassium bromide is proposed. Bundles of nanotubes disperse under superposition of anodic potentials without damage of structure of individual nanotubes as revealed by cyclic voltammetry, electron microscopy, and small-angle X-ray scattering. On the basis of elemental and thermogravimetric analyses data obtained for the initial and processed samples, the mechanism of nanotube modification is proposed for potassium bromide electrolysis in aqueous solution.

Isothermal titration calorimetry, transmission electron microscopy, and field emission scanning electron microscopy of a main-chain viologen polymer containing bromide as counterions

The interaction of a main-chain viologen polymer containing bromide as counterions with water and aqueous potassium bromide over a broad range of concentrations was studied with isothermal titration calorimetry. The dilution process of this polymer was endothermic as opposed to flexible poly(sodium acrylate) and poly(sodium styrenesulfonate). This result may be related to the different mechanism of hydration of pyridinium and bromide groups in the main chain. It also exhibited aggregation phenomenon in both water and aqueous potassium bromide solutions as detected by transmission electron microscopy like other flexible and rigid-rod polyelectrolytes. As the polymer concentrations in aqueous solutions increase, the aggregated polymer exhibited more defined ordered structures than random structures observed at low polymer concentrations. Field emission scanning electron microscopy also revealed the effect of variation of concentration of aqueous potassium bromide on the morphology of the polymer matrix. At increasing concentrations of aqueous potassium bromide, the polymer structures became more ordered than those in low concentrations.

Design and self-assembly of open, regular, 3D mesostructures

Self-assembly provides the basis for a procedure used to organize millimeter-scale objects into regular, three-dimensional arrays ("crystals") with open structures. The individual components are designed and fabricated of polyurethane by molding; selected faces are coated with a thin film of liquid, metallic alloy. Under mild agitation in warm, aqueous potassium bromide solution, capillary forces between the films of alloy cause self-assembly. The structures of the resulting, self-assembled arrays are determined by structural features of the component parts: the three-dimensional shape of the components, the pattern of alloy on their surfaces, and the shape of the alloy-coated surfaces. Self-assembly of appropriately designed chiral pieces generates helices.

The vapour pressures of saturated aqueous solutions of potassium bromide, ammonium sulfate, copper(II) sulfate, iron(II) sulfate, and manganese(II) dichloride, at temperatures from 283 K to 308 K

Vapour pressures of saturated aqueous of KBr, (NH4)2SO4, CuSO4, FeSO4, and MnCl2 were measured in the 283 K to 308 K temperature range using an evaporimetric technique and were compared with the literature values. From the vapour pressures, the water activities, osmotic coefficients, and molar enthalpies of vaporization and solution at saturation were evaluated.

Effect of alcohols and temperature on the structural transitions of CTAB micelles in aqueous potassium bromide solution

The effect of addition of n-alcohols on the viscosity of cetyltrimethylammonium bromide (CTAB) micellar solution in the presence of KBr at various temperatures is presented. Lower alcohols (C 2 and C 3) were found to decrease the viscosity of CTAB solution in the presence of KBr right from the beginning. The viscosities of micellar solutions were found to increase on the addition of 1-butanol, 1-pentanol and 1-hexanol in low concentrations. Depending on the nature of the alcohol, further addition of these alcohols either made the solution turbid or lowered the viscosity of the solutions. The thermodynamic parameters for the viscous flow of micellar solutions in the presence of alcohols have been determined. The results are interpreted in terms of the possible transition of micellar shape from rod to sphere or to elongated rods in the presence of added alcohols.

Liquid-expanded to liquid-condensed phase transition in polyelectrolyte monolayers on the aqueous potassium bromide solution. 1. Salt concentration dependence

Etude de sels de polyvinylpyridinium quaternarises (a partir de l'autopolymerisation de vinyl-4 pyridine et de trois bromures de n-alkyle)

Solubility of copper (I) bromide in aqueous solutions of potassium bromide

The solubilities of cuprous bromide were measured at 24.8°C in aqueous KBr and in aqueous KBr-KNO3 mixtures. The results have been analyzed to give equilibrium constanns from formation of neutral and negatively charged complexes of CuBr, and sets of virial parameters suitable for calculation of activity coefficients for the complexes.

Functional monomers and polymers, 85. On the adsorption of bromine onto chitosan

AbstractThe adsorption of bromine onto powdery chitin, chitosan and cellulose was studied in an aqueous bromine‐potassium bromide solution at 30°C. Chitosan was found to show an excellent ability of adsorbing bromine as well as iodine. The chitosan film also exhibited high ability of adsorbing bromine both in methanol and in aqueous potassium bromide solutions.

Studies on the Aqueous Solutions of Guanidinium Salts. XIV. Effect of Guanidinium Bromide on the Surface Tension of Aqueous Solutions of the Cationic Surfactants

Abstract The surface tensions of decyl-, tetradecyl-, and hexadecyl-trimethylammonium bromides were measured in the aqueous solutions of potassium bromide (KBr) and guanidinium bromide (GuBr). The critical micelle concentrations (CMC’s) of the above surfactants decreased with increase of the concentration of KBr, while the CMC’s showed minimum values in the aqueous GuBr solution, as the concentration of GuBr increased. The Langmuir coefficient, KC, increased with decrease of the CMC. The influence of the salts on the surface tension and the micellization were well described in terms of the activity of the surfactant calculated by combining the Debye-Hückel law and Setschenow’s equation.

Novel radiolytic species in aqueous potassium bromide solutions as studied by pulse radiolysis

The tribromide ion-radical, Br 3 2−, and its protonated form HBr 3 − have been observed in the pulse radiolysis of 0·3 mol dm −3 aqueous KBr solutions. Br 3 2− and HBr 3 − have optical absorption maxima at 270 nm and 360 nm. The molar extinction coefficients of Br 3 2− and HBr 3 − are 224 and 445 m 2/mol at 270 nm, and at 360 nm 1020 and 840 m 2/mol respectively. These species are in equilibrium with dibromide ion-radicals, i.e. Br 3 2− ⇋ Br 2 − + Br −, pK = 1·3, HBr 3 − ⇋ Br 2 −+H ++Br −, pK = 1·0, and HBr 3 − ⇋ Br 3 2− + H +, pK = 3·7.

Activity coefficient assumptions in the determination of association constants. V. Association of thallium(I) bromide from solubility measurements

Measurements are reported of the solubility of thallium(I) bromide in aqueous solutions of potassium bromide, sodium perchlorate, barium bromide, and of mixtures of sodium bromide and sodium perchlorate and of sodium bromide and sodium acetate at 25�. The measurements are used to test the merits of two types of ionic activity coefficient expressions, one assuming specific interactions between free ions and the other not. It is shown that neither expression can describe our results adequately, in contrast to previous solubility results with thallium(I) chloride for which the specific interaction expression was adequate.

Synthesis of organomercury compounds from hydrazones Communication 1. Reaction of hydrazones of aliphatic aldehydes and ketones with mercuric acetate

1. The reaction of acetaldehyde, acetone, methylethyl ketone and butyrone hydrazones with mercuric acetate p rovides a method of preparation of some new types of organomercury compounds. 2. This reaction is of the “conjugated addition” type with the medium taking part. In water, α,α′-dimercurated or α,α′,ββ′-tetramercurated ethers are formed, in methanol-α-mercurated or α,β-dimercurated alkylmethyl ethers, and finally in absolute benzene — a-mercurated or α,β-dimercurated alkyl acetates. 3. The chemical properties of the organomercury compounds obtained have been studied and it was shown that: a) the dimercurated compounds of types (IV–VI) decompose on heating with concentrated hydrochloric acid with liberation of mercurous chloride and formation of the corresponding carbonyl compound; b) bromination of dimercurated compounds of types (IV–VI) with bromine and saturated aqueous potassium bromide solution in the cold leads to the formation of the corresponding α-bromoketone in addition to the ketone; c) the monomercurated compounds of types (I-III) decompose in concentrated alkali in the cold with liberation of metallic mercury and formation of the corresponding carbonyl compound.

The Thermodynamics of Aqueous Solutions of Potassium Bromide at 25° from e. m. f. Measurements on Cells with Transference

The Thermodynamics of Aqueous Solutions of Potassium Bromide at 25° from e. m. f. Measurements on Cells with Transference

The Transference Numbers of Potassium Bromide in Aqueous Solution at 25°C

The transference numbers for aqueous solutions of potassium bromide at 25°C have been determined by the moving boundary method. Cells with cadmium bromide and lithium bromide as cation indicators and with potassium iodate as anion indicator were employed. The measurements are more difficult than with potassium and sodium chlorides; with sheared junctions, a thorough investigation of the effect of indicator concentration is necessary for each solution studied, and the same is true with both sheared and autogenic boundaries of the effect of current density. The results differ slightly from those previously reported by Longsworth, but are consistent with the known value of t+0. Potassium bromide also differs from the alkali chlorides and acetates in that the Longsworth function t+0′ is not linear in the concentration, thus precluding an independent extrapolation of the transference data.

The Conductance of Aqueous Solutions of Potassium Bromide at Temperatures from 15° to 45°C, and the Limiting Mobility of Bromide Ion

The conductance of aqueous solutions of potassium bromide at concentrations from 0.0005 N to 0.01 N for temperatures from 15° to 45° C has been measured by the direct-current method previously employed for potassium and sodium chlorides. At 15°, there is a small logarithmic term required to represent the Shedlovsky function Λ′0, but for 25° and higher temperatures, Λ′0 is linear in the concentration. The limiting mobility of bromide ion is obtained from the limiting conductance and the known mobility of potassium ion; the temperature coefficients of the limiting bromide ion mobility are uniformly about 2 percent less than the corresponding values for chloride ion.