Aqueous Bromide Solutions Research Articles

The Effect of a Background Electrolyte on the Viscosity of Aqueous Dodecyltrimethylammonium Bromide Solutions

Conductometry and viscometry have been employed to study the effect of a background electrolyte (KBr) taken in concentrations of 0.03 and 0.1 M on the critical micelle concentration of dodecyltrimethylammonium bromide (С12ТАB) and the dependence of relative viscosity η/η0 of С12ТАB micellar solutions on the overall surfactant concentration. It has been found that, as a first approximation, each of these dependences may be represented as the sum of two linear portions. Concentrations c* of С12ТАB micellar solutions, which correspond to the inflections between the two linear portions in the concentration curves of relative viscosity, have been determined. The Einstein equation η/η0 = 1 + 2.5p (p is the volume fraction of the dispersed phase and 2.5 is a theoretical parameter that takes into account the spherical shape of the particles) has been transformed into a form corresponding to the concentration dependence of the relative viscosity on the overall surfactant concentration to make it applicable to the consideration of low-concentration systems, which are uncomplicated by intermicellar interaction. In particular, the applicability of the above equation for estimating micelle radii has been studied. It has been shown that the (η/η0–1) = f(c/с01–1) concentration dependences represented in bilogarithmic coordinates (c is the overall С12ТАB concentration and c01 is the critical micelle concentration) are linear in the absence of a significant intermicellar interaction and have slopes equal to unity. This fact may be considered as a criterion for the applicability of the Einstein equation to micellar solutions.

Heat and Mass Transfer Enhancement for Falling Film Absorption Process in Vertical Plate Absorber by Adding Copper Nanoparticles

This paper examined the effect of nanoparticles on the absorption of vapor into a liquid film of lithium bromide aqueous solution flowing down over a cooled vertical channel. For this, we realized a two-dimensional code which solves the governing equations using Comsol Multiphysics. In this model, the cooling water flows countercurrent to a solution of concentrated lithium bromide mixed with the copper nanoparticles. After the validation of the model, the effects of parameters such as Reynolds number, solid volume fraction of copper nanoparticles, inlet concentration and inlet temperature of solution on the performance of the absorption are presented and discussed. The important results indicate that the mass and heat transfer in binary nanofluids are enhanced more than that in base fluid and the efficiency of the nanofluid becomes higher to that of the base fluid for a lower Reynolds number and the inlet concentration and for a higher inlet temperature of solution.

Determination of bromide in aqueous solutions via the TlBr molecule using high-resolution continuum source graphite furnace molecular absorption spectrometry

The paper describes the determination of bromide by evaluating the molecular absorption of thallium mono-bromide (TlBr) at the rotational line at 342.9815nm by making use a high-resolution continuum source graphite furnace atomic absorption spectrometer. The effects of variables such as the wavelength, graphite furnace program, amount of Tl and the use of a modifier were investigated and optimized. Various chemical modifiers have been studied, such as Pd, Mg, Ag and a mixture of Pd/Mg. It was found that best results were obtained by using Ag which prevents losses of bromide during pyrolysis step through precipitation of bromide as AgBr. In this way, a maximum pyrolysis temperature of 400°C could be used. The optimum molecule forming temperature was found to be 900°C. Bromide concentrations in various water samples (CRM, bottled drinking water and tap water) were determined. The quantification was made by both linear calibration and standard addition techniques. The results were matched well those of the reference method. The calibration curve was linear in the range between 1 and 1000ng Br with a correlation coefficient R=0.999. The limit of detection and characteristic mass of the method were 0.3ng and 4.4ng of Br.

Investigation on mass transfer characteristics of the falling film absorption of LiBr aqueous solution added with nanoparticles

A set of mathematical models is developed based on energy and mass conservation to predict the mass transfer characteristics of falling film absorption of lithium bromide (LiBr) aqueous solution added with nanoparticles. Experimental measurements are conducted to validate the mathematical models, and good agreement is acquired. Simulations are performed to investigate the mass transfer of LiBr aqueous solution added with nanoparticles. Results showed that nanoparticles could significantly improve the water vapor absorption rate of nanofluid in the process of falling film absorption. Moreover, the water vapor absorption rate increased with the number of nanoparticle additives. With the same number of nanoparticles, the water vapor absorption rate of LiBr solution increased with the solution flow and with the change of solution flow trend for logarithmic curve. The mass transfer enhancement factor also increased with the number of nanoparticles. In addition, the mass transfer coefficient of absorber increased with the number of nanoparticle additives. When the flow rate of nanofluid with 0.05% and 0.1% added nanoparticles was 1.0 L min−1, the mass transfer coefficient increased by 1.28 and 1.41 times, respectively. These results are beneficial in improving the mass transfer of the working medium used for an absorption refrigeration cycle and enhancing the performance of an absorption chiller.

Investigation on the interfacial behavior of aqueous solutions of cetyltrimethyl ammonium bromide in the presence of polyethylene glycols

The surface tensions of aqueous cetyltrimethyl ammonium bromide and four polyethylene glycols were measured experimentally at the temperature of 298.15 K and the pressure of 1 atm. Then the surface tensions of aqueous (cetyltrimethyl ammonium bromide + polyethylene glycols) were measured at different concentrations. These measurements were conducted with the pendant drop method. The surface tensions of these aqueous solutions were described by using the equality of chemical potentials at the interface and bulk liquid. The calculated results showed a good agreement with experimental measurements, so the model was successfully applied to aqueous cetyltrimethyl ammonium bromide, polyethylene glycols, and their mixtures. Moreover, the surface coverage, molar surface area, and surface-to-solution distributions were determined by this model. The values of critical micelle concentration were obtained through surface tension measurements for each aqueous solution. The presence of polyethylene glycols increased the values of the critical micelle concentration and decreased the surface coverages of cetyltrimethyl ammonium bromide.

Vapor Pressure Measurement for the Ternary System of Water, Lithium Bromide, and 1-Ethyl-3-methylimidazolium Acetate

To improve the performance of an absorption system, ionic liquids (ILs) have been chosen as additives to conventional working fluid (lithium bromide aqueous solution) in recent years. In this paper, 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) was added to lithium bromide aqueous solution (mass ratio LiBr/[Emim]Ac = 3) to measure the vapor–liquid equilibrium (VLE) data of the ternary system. The experiment was conducted by means of boiling point method, at temperatures between 303.94 K and 405.41 K and mass fractions of absorbent between 0.20 and 0.60. The experimental data were regressed using an Antoine-type equation, and the average absolute relative deviation (AARD%) between the experimental and calculated values was 0.34%, which showed excellent accuracy and consistency. The experimental ternary system was compared with the conventional LiBr + H2O system and two other ternary systems from the literature; the result revealed that the experimental ternary system had lower vapor pressures, which will ...

Kinetics Study of Heterogeneous Bromine Release from the Reaction between Gaseous Ozone and Aqueous Bromide Solution.

The heterogeneous release of molecular bromine, Br2, from the reaction between gaseous ozone and aqueous bromide ion in seawater ice and sea salt aerosols is considered to be an initial source of reactive bromine species in the troposphere. Recent studies have demonstrated that the uptake of ozone by aqueous bromide solution is promoted by reactions at the gas-liquid interface. The present work investigated the heterogeneous reaction between gaseous ozone and aqueous bromide solution at atmospheric pressure and room temperature using a wetted wall flow reactor combined with a chemical ionization mass spectrometer. The emission rate of Br2 was measured as a function of gaseous ozone concentration, aqueous bromide concentration, and pH. In addition, we conducted a simple kinetics model simulation that included only bulk aqueous-phase reactions and compared the theoretical values with the experimentally determined values. The Br2 emission rates measured experimentally differ from the simulated rates at relatively high bromide concentration, as well as in the pH region of 6-9. These differences might be explained by different Br- concentration and/or deprotonation efficiency near the interface region and those in the bulk solution.

Semi-clathrate hydrate process of methane in porous media-mesoporous materials of SBA-15

The hydrate based technology process in porous media is an effective method for gas storage and separation. The formation of methane hydrate in SBA-15, an ordered mesoporous silicon material, was measured with tetrahydrofuran (THF) and tetra-n-butyl ammonium bromide (TBAB) aqueous solution at different pressure and temperature·THF and TBAB were selected to lower the equilibrium pressure at which the gas hydrates can efficiently formed. At the experimental condition of 1.8 MPa–2.0 MPa, SBA-15 was proved to be effective to methane uptake in the hydrates. The results showed that mesoporous silica can help to get the fast-kinetic formation of methane hydrates. The temperature was almost steady and only had two slight increase no more than 0.5 K. The pressure dropped rapidly and then became gentle, which translated into an increase in gas uptake rapidly in the beginning of 100 min and then maintained stable till the end. The reaction rate quickly reached the peak then rapidly dropped and slowly decayed. The desirable kinetics parameters of final gas uptake capacity, average of reaction rate and conversion of gas to hydrate (%) were obtained at higher pressure and lower temperature while THF was better than TBAB. A gas uptake capacity of 91.13 mmol methane gas per mole water was achieved when the hydrates were formed in the presence of THF with SBA-15.

Semi-clathrate hydrate process of methane in porous media-microporous materials of 5A-type zeolites

Porous media can significantly promote the kinetics of hydrate formation by reducing the barrier of physical chemistry, where zeolites are typical microporous minerals. In this paper, the formation process and the reaction kinetics of the methane hydrate were investigated in A-type zeolite with tetrahydrofuran (THF) and tetra-n-butyl ammonium bromide (TBAB) aqueous solution in a long tubular reactor. The results showed that good kinetic characteristics of methane hydrate formation can be achieved with A-type zeolite. At initial pressure of 1.5 MPa and 1.8 MPa at 285.15 K, the aqueous solution of tetrahydrofuran (THF) and tetra-n-butyl ammonium bromide (TBAB) with 5A-type zeolite can form methane hydrate with gaseous methane in 10 h. The temperature raised significantly during the formation process of the system with 5A-type zeolite. Throughout the reaction, there was an obvious temperature rising region which was located in the inlet side of tubular reactor. The gas uptake increased rapidly in the beginning of 100 min and then maintained stable increasing during the hydrate formation. The final gas uptake capacity raised with the reaction pressure but was little affected by the type of promoter. From 1.5 MPa to 1.8 MPa the final gas uptake of hydrate increased 6.48% and 6.15% in the THF and TBAB solution respectively. The reaction rate quickly reached the peak after the reaction began and then rapidly dropped to decays. Simultaneously the average of reaction rate of THF solution was 13.2–30.8% higher than that of TBAB solution when the pressure was 1.5 MPa and 1.8 MPa at the same experimental conditions.

Effect of amino acid addition on the micelle formation of the surface‐active ionic liquid 1‐tetradecyl‐3‐methylimidazolium bromide in aqueous solution

AbstractThe effect of 3 amino acids on the self‐assembly properties of the surface‐active ionic liquid: 1‐tetradecyl‐3‐methyl imidazolium bromide, [C14mim][Br], was studied in neutral and basic aqueous solution. The critical micelle concentrations were determined by different techniques, and the thermodynamic parameters of micellization (ΔG0mic, ΔH0mic, and ΔS0mic) were measured by isothermal titration calorimetry.The critical micelle concentration values decrease in the presence of all the amino acids used in this study. The most substantial effect was observed in the presence of L‐tryptophan at pH 12, due to the electrostatic and π‐π interactions with the imidazolium headgroup of the surfactant. Always entropy‐driven micellization occurred. Both the enthalpy and entropy changes upon association to micelles increased when the pH was enhanced from 7 to 12.1H NMR measurements demonstrated that among the used amino acids, L‐tryptophan interacts most strongly with the headgroup of the surfactant cation.The knowledge on the surfactant‐amino acid interactions significantly contributes to the deeper understanding of the effect of surfactants on the properties of peptides.

Antifouling enhancement of polyimide membrane by grafting DEDA-PS zwitterions

In order to improve the water flux and antifouling property of polyimide (PI) membrane, zwitterions are grafted on PI membrane surface via a two-step modification route by reactions with N,N-diethylethylenediamine (DEDA) and 1,3-propane sultone (PS) sequentially. The reaction mechanism and physicochemical properties of membranes are confirmed via various characterization techniques. The anti-biofouling performance of the zwitterion-grafted PI membranes is evaluated by bacterial suspension immersion tests in Escherichia coli (E. coli) and staphylococcus aureus (S. aureus) solutions. The antifouling property is assessed via the filtration test using the bovine serum albumin (BSA) and dodecyl trimethyl ammonium bromide (DTAB) aqueous feed solutions. The effect of the reaction time with DEDA in the zwitterion-grafted process on the antifouling property is further investigated systematically. The results show that both the anti-biofouling and antifouling performances of zwitterion-grafted PI membranes are significantly improved.

Solubility and Thermodynamics of Solute–Solvent Interactions of Some Amino Acids in Aqueous Sodium Bromide and Potassium Bromide Solutions

The study presents the saturated solubilities of four amino acids such as glycine, dl-alanine, dl-valine, and dl-serine in water media containing sodium bromide and potassium bromide electrolytes at standard temperature (298.15 K) which were evaluated by applying the “gravimetric method”. Various physicochemical and thermodynamical parameters such as enthalpy of solvation, free energy change, density, molar volume, solvent diameter, cosolvent diameter, apparent dipole moment of aqueous electrolyte systems, mole fraction of salt and solvent, mean molecular weight of electrolyte solvent and isothermal expansibility constant of aqueous electrolytes were estimated at standard temperature (298.15 K). The characteristics and degree of solubilities of the experimental molecules in water media in the presence of NaBr and KBr were examined by means of the salting-in effect which was further justified by relative solubility and salting-in constants. Various reasonings influencing the solubility were introduced and ...

Effect of Additives on the Phase Behavior of SDS/CTAB/H2O Systems

Abstract The effect of additives on the phase behavior of aqueous solutions of sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) has been studied in detail for extended applications. The results showed that both the widths of an anionic two-phase aqueous system (ATPSa) region with SDS in excess and a aqueous cationic two-phase system (ATPSc) region with CTAB in excess are very narrow, less than 1% in absence of any additives. However, phase regions of ATPS move toward the corresponding isotropic single phase regions and become wider in the presence of inorganic additives such as NaBr in the aqueous surfactant solutions. This is because the addition of inorganic salt increases the concentration of inorganic counter-ions and therefore the electrostatic interactions between counter-ions and surfactant aggregates. Meanwhile, the organic salts, sodium salicylate and tetrabutylammonium bromide, have been found to have a greater capacity to expand the range of ATPS because the electrostatic interactions between organic ions and aggregates were adjustable through the deformation of the electron cloud of organic ions. Organic additives with different properties can effectively extend the range of either ATPSc or ATPSa. Wherein, sodium salicylate can expand ATPSc efficiently and tetrabutylammonium bromide can expand ATPSa significantly.

Pitting Corrosion Behavior of 304 SS and 316 SS Alloys in Aqueous Chloride and Bromide Solutions

The importance of the present work falls on the pitting corrosion behavior investigation of 304 SS and 316 SS alloys in 3.5 wt% of aqueous solution bearing with chloride and bromide anion at different solutions temperature range starting from (20-50)oC due to the pitting corrosion tremendous effect on the economic, safety and materials loss due to leakage. The impact of solution temperatures on the pitting corrosion resistance at 3.5wt% (NaCl and NaBr) solutions for the 304 SS and 316 SS has been investigated utilizing the cyclic polarization techniques at the potential range -400 to1000 mV vs. SCE at 40 mV/sec scan rate followed by the surface characterization employing Scanning Electron Microscope. The results show that a significant decline in the pitting corrosion potential Ep values of both stainless steel alloys in chloride and bromide solution during temperature increase attributed to the pitting corrosion potential decreased arises from the modification of the passive film properties. The surface examination using optical microscope and scanning electron microscope prove the occurring of higher pitting density over 304 SS in chloride solution than that observed in bromide solution with a non-circular lacy cover pitfall out at the center and falls inside the pits hall in comparison to the isolated circular lacy cover pit formed on 316 SS in 3.5wt% NaBr solution at 50 oC.

Effects of Fructose and Temperature on the Micellization of a Cationic Gemini Surfactant, Pentanediyl-1,5-bis(dimethylcetylammonium) Bromide in Aqueous Solutions

By the conductivity measurements the effects of fructose and temperature (293–308 K) on the micellization of a cationic gemini surfactant (GS), pentanediyl-1,5-bis(dimethylcetylammonium) bromide in aqueous solutions have been investigated. The critical micelle concentration (CMC) of GS was measured at the different temperatures and fructose concentrations. An increasing trend of the CMC values is with addition of fructose. With increasing temperature, the CMC values are in a similar increasing trend. The CMC of GS by dye solubilization method at room temperature have been determined. The standard Gibbs energy, enthalpy and entropy of GS micellization have been evaluated. From these thermodynamic parameters, it was found that in presence of fructose, the stability of the GS aqueous solutions decreases.

Ordering in Surfactant Foam Films Transferred onto Hydrophilic and Hydrophobic Substrates

Foam films have been formed by aqueous dodecyldimethylphosphine oxide (C12DMPO) and aqueous hexadecyltrimethylammonium bromide (C16TAB) solutions and drained. The surfactant films were transferred onto hydrophilic and hydrophobic substrates at five different drainage times. Angle-resolved X-ray photoelectron spectroscopy and metastable induced electron spectroscopy were used for investigation of the thickness and orientation of the surfactant molecules in the transferred foam film. Of the four combinations only the drained film formed by C16TAB transferred onto hydrophobic surfaces shows a strong degree of orientation of the surfactant molecules in the transferred film. The other three combinations do not show a preferred orientation of the surfactant molecules in the foam film. The phenomenon is discussed based on the interaction of the molecules within the films and the interaction of the formed films with the substrates.

Experimental and modeling study of the surface tension and interface of aqueous solutions of alcohols, cetyltrimethylammonium bromide (CTAB) and their mixtures

In this study, the experimental surface tensions were measured for aqueous solutions of cetyltrimethyl ammonium bromide, 1-propanol, 2-propanol, and 1-butanol with a pendant drop apparatus. The temperature and pressure of all experiments were 298.15K and 1bar, respectively. Subsequently, a model based on the equality of the chemical potential of components at the interface and the bulk liquid was used. The results of this part showed that the surface tensions were reproduced well. The average absolute deviation percent of surface tension was 1.11. Then the surface tensions of (cetyltrimethylammonium bromide+alcohols) aqueous mixtures were measured at different concentrations. Moreover, the critical micelle concentrations of the applied systems were determined. The present model was used for aqueous mixtures of (cetyltrimethylammonium bromide+alcohols). The average absolute deviation percent of surface tension was 2.72, so the model successfully predicted the surface tension for aqueous solutions of (cetyltrimethylammonium bromide+alcohols). Furthermore, the results of the model proved that the presence of alcohols decreased the surface coverage of cetyltrimethylammonium bromide and increased the values of the critical micelle concentration.

Antifouling polyimide membrane with grafted silver nanoparticles and zwitterion

Abstract In order to improve the antibacterial and antifouling properties of polyimide (PI) membrane, both silver nanoparticles (AgNPs) and zwitterionic sulfobetaine methacrylate (SBMA) are grafted onto PI membrane surface via a two–step modification route. The reaction mechanism involved, as well as changes in the membrane morphology and surface properties are investigated via various characterization techniques. The antibacterial performance is assessed by the zones of inhibition and bacterial suspension immersion tests. The antifouling property of the modified membrane is evaluated via the filtration test using the bovine serum albumin (BSA) and dodecyl trimethyl ammonium bromide (DTAB) aqueous feed solutions. The results show that, the modified PI membrane exhibits significantly improved antibacterial and antifouling performances simultaneously.

Modulation of the aggregation behaviour and physicochemical properties of 1-dodecyl-3-methylimidazolium bromide in aqueous solutions by β-CD

ABSTRACTThe modulation of aggregation behaviour of ionic liquids (ILs) in aqueous media is one of the important research topics. In the present work, aggregation behaviour of 1-dodecyl-3-methylimidazolium bromide ([C12mim]Br) modulated by beta-cyclodextrin (β-CD) has been investigated by using conductivity, volume, fluorescence, dynamic light scattering and transmission electron microscopy techniques. The results suggested that the addition of β-CD significantly affects the aggregation of [C12mim]Br in aqueous solutions. For example, the apparent critical micelle concentration increases with the increase of β-CD concentration; the average micellar size reduced with the increasing concentration of β-CD, and the process for micelle formation of [C12mim]Br in aqueous β-CD solution is driven by entropy at lower temperature, while driven by enthalpy at higher temperature. It is expected that findings in this study would shed light on the potential applications of IL in supramolecular chemistry.

Interactions of sodium polystyrene sulfonate with 1-hexyl-3-methylimidazolium bromide in aqueous solution: conductometry and density functional theory studies

ABSTRACTConductivity measurements of sodium polystyrene sulfonate (NaPSS) were carried out in aqueous solutions of 1-hexyl-3-methylimidazolium bromide ([HMIm]Br) at three different temperatures. The scaling theory is used for the description of electrical conductance of polyelectrolytes. The fraction of uncondensed counterions is decreased by increasing temperature and concentration of [HMIm]Br. Conductivity measurements of ([HMIm]Br were accomplished in aqueous solutions of sodium polystyrene sulfonate. Data analysis was performed by the Quint–Viallard conductivity equation and low concentration chemical model. Molar conductivity of [HMIm]Br in aqueous solutions of NaPSS was increased with increasing temperature. The values of activation energy for viscous flow are higher than the values of activation enthalpy of charge transport; therefore, it can be concluded that in addition of ion transfer, the formation and breaking hydrogen has a portion in charge transfer. The results of Quantum chemical calculations confirm the existence of hydrogen bonding between [HMIm]+ and [PSS]–.