Sodium Bromide Concentration Research Articles

Analysis of the Composition of Bromide Anion Oxidation Products in Aqueous Solutions with Different pH via Rotating Ring-Disk Electrode Method.

We measured the ring collection coefficient of bromide anion oxidation products in a neutral and slightly alkaline medium on a rotating ring-disk electrode (glassy carbon disk, platinum ring) varying the following parameters: disk electrode rotation velocity, sodium bromide concentration, pH of the medium (in the range of 6–12), anode current on the disk, and the electroreduction potential of the bromide anion oxidation products on the ring. The data obtained are presented via dependences of the cathode ring current on the disk current ratio vs. the ring electrode potential. The analysis of the results was carried out by comparing the experimental polarization curves of the ring electrode with the data of cyclic voltammetry in model solutions to determine the electrical activities of various bromine compounds in positive oxidation states. We claim that the RRDE method could be used to obtain quantitative and qualitative data on the electrooxidation of bromide ions in neutral and alkaline solutions. For the most effective regeneration of the spent oxidizer, the values of pH > 10 and moderate concentrations of NaBr should be used.

Hydrometallurgical Treatment of Waste Printed Circuit Boards: Bromine Leaching

This paper demonstrates the recovery of valuable metals from shredded Waste Printed Circuit Boards (WPCBs) by bromine leaching. Effects of sodium bromide concentration, bromine concentration, leaching time and inorganic acids were investigated. The most critical factors are sodium concentration and bromine concentration. It was found that more than 95% of copper, silver, lead, gold and nickel could be dissolved simultaneously under the optimal conditions: 50 g/L solid/liquid ratio, 1.17 M NaBr, 0.77 M Br2, 2 M HCl, 400 RPM agitation speed and 23.5 °C for 10 hours. The study shows that the dissolution of gold from waste printed circuit boards in a Br2-NaBr system is controlled by film diffusion and chemical reaction.

Bromination of L-tryptophan in a Fermentative Process With Corynebacterium glutamicum.

Brominated compounds such as 7-bromo-l-tryptophan (7-Br-Trp) occur in Nature. Many synthetic and natural brominated compounds have applications in the agriculture, food, and pharmaceutical industries, for example, the 20S-proteasome inhibitor TMC-95A that may be derived from 7-Br-Trp. Mild halogenation by cross-linked enzyme aggregates containing FAD-dependent halogenase, NADH-dependent flavin reductase, and alcohol dehydrogenase as well as by fermentation with recombinant Corynebacterium glutamicum expressing the genes for the FAD-dependent halogenase RebH and the NADH-dependent flavin reductase RebF from Lechevalieria aerocolonigenes have recently been developed as green alternatives to more hazardous chemical routes. In this study, the fermentative production of 7-Br-Trp was established. The fermentative process employs an l-tryptophan producing C. glutamicum strain expressing rebH and rebF from L. aerocolonigenes for halogenation and is based on glucose, ammonium and sodium bromide. C. glutamicum tolerated high sodium bromide concentrations, but its growth rate was reduced to half-maximal at 0.09 g L−1 7-bromo-l-tryptophan. This may be, at least in part, due to inhibition of anthranilate phosphoribosyltransferase by 7-Br-Trp since anthranilate phosphoribosyltransferase activity in crude extracts was half-maximal at about 0.03 g L−1 7-Br-Trp. Fermentative production of 7-Br-Trp by recombinant C. glutamicum was scaled up to a working volume of 2 L and operated in batch and fed-batch mode. The titers were increased from batch fermentation in CGXII minimal medium with 0.3 g L−1 7-Br-Trp to fed-batch fermentation in HSG complex medium, where up to 1.2 g L−1 7-Br-Trp were obtained. The product isolated from the culture broth was characterized by NMR and LC-MS and shown to be 7-Br-Trp.

Phase Diagram of the Ternary System NaCl−NaBr−H2O at 348 K

The phase diagram of ternary system NaCl−NaBr−H2O at 348 K was studied by the isothermal equilibrium dissolution method. The solubilities of salts and densities of saturated solutions in the ternary system were determined experimentally. The equilibrium solid phases were also determined by chemical analysis and X-ray powder diffraction. Using the experimental data, the phase diagram of the ternary system was plotted. The diagram comprises one univariant curve and one stationary phase in crystallization filed of Na(Cl,Br).The ternary system was of solid solution type. Density values in the equilibrium solution increase with an increase in the sodium bromide concentration while decrease with an increase of the sodium chloride concentration. Based on the above experimental results, the solid solution compositions can fit well with a quadratic function of the equilibrium liquid composition.

Measurements of solid-liquid equilibria in the ternary system NaCl-NaBr-H2O at 373 K

Solid-liquid equilibria in the ternary system NaCl-NaBr-H2O at 373 K were measured by the isothermal dissolution equilibrium method. The solubilities of salts and densities of saturated solutions in the ternary system were determined experimentally. The equilibrium solid phases were also determined by chemical analysis and X-ray powder diffraction. Using the experimental data, the phase diagram of the ternary system was obtained, which comprise one univariant curve and one stationary phase in crystallization filed of Na (Cl, Br). The ternary system was solid solution type. Density values in the equilibrium solution increase with an increase of the sodium bromide concentration while decrease with an increase of the sodium chloride concentration. The relationship equation of equilibrium liquid phase and the solid phase composition data were fitted with a regression equation.

Mean ionic activity coefficient ratio of NaBr and DL-valine in the (water + DL-valine + NaBr + K3PO4) system at T = (298.2 and 303.2) K

The mean ionic activity coefficient of NaBr in the (water+DL-valine+NaBr+K3PO4) system was determined by potentiometry at T=(298.2 and 303.2)K by using two ion-selective electrodes, (Na+) against (Br−). The maximum concentrations of sodium bromide, potassium phosphate, and DL-valine were (1.0, 0.01, and 0.4)mol·kg−1, respectively. The activity coefficient of DL-valine was evaluated from mean ionic activity coefficients of NaBr by using a cross-differential thermodynamic relation.

Effect of the spacer length on the electrostatic interactions of cationic gemini surfactant micelles with trianionic curcumin

The absorption and fluorescence measurements have been used to study the interactions between cationic gemini surfactant micelles of alkanediyl-α,ω-bis(dodecyldimethylammonium bromide) (C12CsC12Br2, where s=2, 3, 4, 6, and 12, indicating the number of carbons in the spacer) with trianionic curcumin (Cur3−) at pH 13. With increasing spacer length of gemini surfactant, the maximum intensities of absorption and fluorescence peaks of Cur3− give the highest values at s=6, reflecting that the spacer length of gemini surfactant significantly regulates the electrostatic attractive interactions between C12CsC12Br2 micelles and Cur3−. The maximum fluorescence intensity of Cur3− in C12C6C12Br2 micelle shows increasing tendency at 0–100mM sodium bromide concentration (CNaBr), but decreases above CNaBr=120mM. This result is explained in terms of the enhanced electrostatic attraction of Cur3− with C12C6C12Br2 micelle at low salt concentrations and the reduced electrostatic attraction at high salt amounts. The determined pKa1 values of curcumin in C12CsC12Br2 micelles support the strongest electrostatic association between C12C6C12Br2 micelle and anionic Cur−. The interaction mechanisms of C12CsC12Br2 micelles with Cur3− have been further proposed at s=2–4, s=6, and s=12, which is related to the matching of the positive charges in C12CsC12Br2 micelles to the negative charges in Cur3−.

Comparative study on the treatment of simulated brominated butyl rubber wastewater by using bipolar membrane electrodialysis (BMED) and conventional electrodialysis (ED)

A large amount of wastewater containing sodium bromide (NaBr) is generated during the production of brominated butyl rubber. In our previous job, bipolar membrane electrodialysis (BMED) was used to regenerate hydrobromic acid (HBr) and sodium hydroxide (NaOH) from a simulated NaBr wastewater. To give a comparison with previously presented research paper, a desalinization of sodium bromide by using ED was also performed. The effects of operation parameters, such as current density, sodium bromide concentration, and initial acid and base concentrations in the concentrate, on desalinization were analyzed. In comparison, BMED has higher desalinization ratio and current efficiency, and much lower voltage drop and energy consumption. The process cost is estimated to be 0.82$/kg NaBr for BMED and 1.01$/kg NaBr for ED. Notably, BMED can also regenerate NaOH and HBr. Therefore, BMED will be more economically attractive and environmental benignity due to the regeneration of useful resource and prevention of secondary pollution.

Treatment of simulated brominated butyl rubber wastewater by bipolar membrane electrodialysis

A large amount of wastewaters containing sodium bromide (NaBr) is usually generated during the production of brominated butyl rubber; it can cause contamination of the environment. In this study, a method was reported to regenerate hydrobromic acid (HBr) and sodium hydroxide (NaOH) from a simulated NaBr wastewater by bipolar membrane electrodialysis (BMED). Sodium hydroxide may be recycled in the neutralization washing process of preparing the brominated butyl rubber. The effects of operation parameters, such as sodium bromide concentration, current density, and initial acid and base concentrations, on regeneration were analyzed, on the basis of proper energy consumption and current efficiency. The results indicated that a low energy consumption and a high current efficiency were achieved when the concentration of sodium bromide was in the range of 11,000–16,000 mg/L with both the initial concentration of the acid and base at about 0.10 mol/L. Additionally, it was also demonstrated that a high current density applied to the BMED stack usually resulted in both higher energy consumption and current efficiency. Finally, a discharged NaBr concentration of 133.9 mg/L, which was far below the discharge standard of water pollutants for industry, could be obtained from the initial concentration of 16,000 mg/L after the operation of BMED process for 3.5 h. Therefore, this process cannot only achieve the elimination of environmental pollution, but also the recycling of resources.

Hydrodynamic size of DNA/cationic gemini surfactant complex as a function of surfactant structure

The present study deals with the determination of hydrodynamic size of DNA/cationic gemini surfactant complex in sodium bromide solution using the dynamic light scattering method. Cationic gemini surfactants with polymethylene spacer of variable length were used for the interaction with DNA. The scattering experiments were performed at constant DNA and sodium bromide concentrations and variable surfactant concentration in the premicellar and micellar regions as a function of surfactant spacer length. It was found that the DNA conformation strongly depends on the polymethylene spacer length as well as on the surfactant concentration relative to the surfactant critical micelle concentration. Gemini surfactant molecules with 4 methylene groups in the spacer were found to be the least efficient DNA compacting agent in the region above the surfactant cmc. Gemini molecules with the shortest spacer length (2 methylene groups) and the longest spacer length (8 methylene groups) investigated showed the most efficient DNA compaction ability.

Conductance study of the thermodynamics of micellization of 1-hexadecylpyridinium bromide in mixed solvents containing dilute electrolyte solutions

The critical micelle concentration (CMC) of hexadecylpyridinium bromide (HDPB) is determined conductometrically in binary mixtures of water + cosolvent at various temperatures and at low concentrations of sodium bromide, ranging from 0 to 2.4 × 10−2 M. Dimethylsulfoxide (DMSO) and acetonitrile (AN) were used as cosolvents added to water. The ability of NaBr to lower the CMC of HDPB in water is inhibited by DMSO and AN. Thermodynamic parameters of micellization ΔHmo, ΔSmo, and ΔGmo are evaluated according to the pseudo-phase model. The contribution of DMSO and AN in the micellization process of HDPB in aqueous electrolyte solutions are discussed in terms of the observed thermodynamic properties.

Crystallization and preliminary characterization of a novel haem-binding protein of Streptomyces reticuli.

Streptomyces reticuli is a soil-growing Gram-positive bacteria that has been shown to secrete a novel haem-binding protein known as HbpS. Sequence analysis reveals that homologues of HbpS are found in a wide variety of bacteria, including different Actinobacteria and the Gram-negative Vibrio cholera and Klebsiella pneumoniae. The in vivo production of HbpS is greatly increased when S. reticuli is cultured in the presence of the natural antibiotic haemin (Fe3+ oxidized form of haem). Mutational analysis demonstrated that HbpS significantly increases the resistance of S. reticuli to toxic concentrations of haemin. Previous data show that the presence of the newly identified two-component sensor system SenS-SenR also considerably enhances the resistance of S. reticuli to haemin and the redox-cycling compound plumbagin, suggesting a role in the sensing of redox changes. Specific interaction between HbpS and SenS-SenR, which regulates the expression of the catalase-peroxidase CpeB, as well as HbpS, has been demonstrated in vitro. HbpS has been recombinantly overexpressed, purified and crystallized in space group P2(1)3, with a cell edge of 152.5 A. Diffraction data were recorded to a maximal resolution of 2.25 A and phases were obtained using the SAD method from crystals briefly soaked in high concentrations of sodium bromide.

Sphere‐to‐Rod Transitions in Cationic Micelles: Quaternary Ammonium Halides+Phenol+Water Systems

Viscosity measurements on aqueous micellar solutions of cationic surfactants containing phenol with and without sodium bromide were made to study the sphere‐to‐rod transitions. Effect of surfactant structure (nonpolar tail, polar head group sizes and counterion), temperature, and phenol and sodium bromide concentration on the viscosity behavior of the surfactant solution is discussed. The sphere‐to‐rod transition is usually indicated by a marked increase in viscosity. While low temperature, high surfactant concentration, presence of salt, and hydrophobic nature of surfactant all favor the formation of rod‐like micelles, the presence of phenol showed peculiar behavior. Initial additions of phenol (up to about 2.5 wt%) showed a marked increase in viscosity, independent of the nature and concentration of surfactant and temperature; lower viscosities were observed at higher phenol concentration. Conductance and sound velocity results support the viscosity results.

Salt Effect on the Complex Formation between Polyelectrolyte and Oppositely Charged Surfactant in Aqueous Solution

The complex formation between sodium carboxymethylcellulose (NaCMC) and dodecyltrimethylammonium bromide (DTAB) at various sodium bromide concentrations (C(NaBr)) has been studied by microcalorimetry, turbidimetric titration, steady-state fluorescence measurements, and the fluorescence polarization technique. The addition of salt is found to influence the formation of NaCMC/DTAB complexes markedly. At C(NaBr) = 0.00, 0.01, 0.02, 0.10, and 0.20 M, DTAB monomers form micelle-like aggregates on NaCMC chains to form NaCMC/DTAB complexes above the critical surfactant concentration (C1). At C(NaBr) = 0.23 M, DTAB molecules first form micelles above a 2.46 mM DTAB concentration prompted by the added salt, and then, above C1 = 4.40 mM, these micelles can aggregate with NaCMC chains to form NaCMC/DTAB complexes. However, at C(NaBr) = 0.25 M, there is no NaCMC/DTAB complex formation because of the complete salt screening of the electrostatic attraction between DTAB micelles and NaCMC chains. It is also surprisingly found that the addition of NaBr can bring out a decrease in C1 at C(NaBr) < 0.20 M. Moreover, the addition of NaBr to a mixture of 0.01 g/L NaCMC and 3.6 mM DTAB can directly induce the formation of NaCMC/DTAB complexes. This salt-enhancing effect on the complex formation is explained as the result of competition between the screening of interaction of polyelectrolyte with surfactant and the increasing of polyelectrolyte/surfactant interaction owing to the growth of micelles by added salt. When the increasing of polyelectrolyte/surfactant interaction exceeds the screening of interaction, the complex formation can be enhanced.

Measurement of activity coefficients of amino acids in aqueous electrolyte solutions: experimental data for the systems (H 2O + NaBr + glycine) and (H 2O + NaBr + l-valine) at T=298.15 K

Electrochemical cells with two ion-selective electrodes, a cation ion-selective electrode against an anion ion-selective electrode, were used to measure the activity coefficient of amino acids in aqueous electrolyte solutions. Activity coefficient data were measured for (H 2O + NaBr + glycine) and (H 2O + NaBr + l-valine) at T=298.15 K. The maximum concentrations of sodium bromide, glycine, and l-valine were (1.0, 2.4, and 0.4) mol · kg −1, respectively. The results show that the presence of an electrolyte and the nature of both the cation and the anion of the electrolyte have significant effects on the activity coefficients of amino acid in aqueous electrolyte solutions.

Crossover from Ising to mean-field critical behavior in an aqueous electrolyte solution

The near-critical behavior of the susceptibility deduced from light-scattering measurements in a ternary liquid mixture of 3-methylpyridine, water, and sodium bromide has been determined. The measurements have been performed in the one-phase region near the lower consolute points of samples with different concentrations of sodium bromide. A crossover from Ising asymptotic behavior to mean-field behavior has been observed. As the concentration of sodium bromide increases, the crossover becomes more pronounced, and the crossover temperature shifts closer to the critical temperature. The data are well described by a model that contains two independent crossover parameters. The crossover of the susceptibility critical exponent γ from its Ising value γ=1.24 to the mean-field value γ=1 is sharp and nonmonotonic. We conclude that there exists an additional length scale in the system due to the presence of the electrolyte which competes with the correlation length of the concentration fluctuations. An analogy with crossover phenomena in polymer solutions and a possible connection with multicritical phenomena is discussed.

Indium as internal standard in square wave anodic stripping analysis of lead in blood with microelectrode arrays.

The toxic effects of lead on humans, especially children have been well documented. ASV has been an important technique in the analysis of lead in blood of humans. This research has demonstrated that indium(III) can be used as an internal standard in the analysis of lead in blood samples with mercury film microelectrode arrays. Indium is a good choice because of a low endogenous blood concentration and because baseline separation of anodic stripping peaks among Cd, In, and Pb can be achieved under appropriate conditions. The concentration of sodium bromide strongly influences the resolution of these metals and the sensitivity of ASV to In(III) in solution. Square wave anodic stripping voltammetry together with screen-printed microelectrode arrays showed that the ratio of the anodic stripping peak currents of Pb and In varies linearly with the concentration of Pb in blood samples ranging from 1.2 to 30.0 micrograms/dL. The average intraassay precision (rsd) was 6.7%.

Effect of Inorganic Electrolyte Concentration on Anionic-Cationic Adsorption Films: 4. Dodecylpyridinium Bromide + Sodium Octylsulfonate + Sodium Bromide

The effect of sodium bromide concentration on the simultaneous adsorption of dodecylpyridinium bromide and sodium octylsulfonate on the free surface of their aqueous solutions has been investigated. The composition of the mixed films adsorbed from equimolar solutions has been evaluated on the basis of the Gibbs adsorption equation and by using the regular solution model, it has been stated that this composition depends on the surface tension value and the concentration of added inorganic electrolyte. The same factors influence the value of the surface interaction parameter β; negative values indicate a strong attraction between the adsorbed components. The concentration ratio of both surfactants in the solution significantly influences the composition of anionic-cationic adsorption films and the mutual interactions of their components. A distinct difference in the effects of NaBr and NaCl on the properties of the mixed monolayers has been also found.

Effect of inorganic electrolyte concentration on anionic-cationic adsorption films. Part 3: Dodecylpyridinium chloride + sodium octylsulfonate + sodium chloride

Abstract The effect of sodium bromide concentration on the simultaneous adsorption of dodecylpyridinium bromide and sodium octylsulfonate on the free surface of their aqueous solutions has been investigated. The composition of the mixed films adsorbed from equimolar solutions has been evaluated on the basis of the Gibbs adsorption equation and by using the regular solution model, it has been stated that this composition depends on the surface tension value and the concentration of added inorganic electrolyte. The same factors influence the value of the surface interaction parameter β; negative values indicate a strong attraction between the adsorbed components. The concentration ratio of both surfactants in the solution significantly influences the composition of anionic-cationic adsorption films and the mutual interactions of their components. A distinct difference in the effects of NaBr and NaCl on the properties of the mixed monolayers has been also found.

The Catalytic Effect of Bromide in the Hypochlorite Oxidation of Linear Dextrins and Inulin

AbstractThe effect of bromide in the hypochlorite oxidation of amylodextrins (short chain amylose) and inulin on the reaction rate was investigated. It was found both in the linear dextrins and inulin oxidation that the rate increases linearly with the sodium bromide concentration, which proves the catalytic effect of this substance. The origin of the catalysis is the rapid Br−/OCl− conversion. The second‐order rate constant of the reactionCarbohydrate + HOBr/OBr− → polycarboxylates + HBr/Br− was determined at pH 9.0 and 294‐298 K.The activation energy for the oxidation of amylodextrins amounts to 67 kJ.mole−1. The highest rate was found at pH 8.25. The reaction rate is almost independent of pH in the region 8.5–9.5. Because of the simultaneous occurrence of bromine, Br3−. hypobromous acid and hypobromite in the pH region investigated, it is difficult to elucidate the oxidation mechanism.