Aqueous Solutions Of NaBr Research Articles

Corrosion performance and mechanisms of tantalum coatings on 316 stainless-steel in subcritical aqueous solutions of NaCl and NaBr

The corrosion behavior of 316 stainless-steel with a tantalum (Ta-316) coating deposited using PVD technology was investigated in subcritical environments containing Cl− and Br− at 290 °C and 6 MPa. The corrosion rate of Ta-316 continuously decreased with increasing exposure time, demonstrating its high corrosion resistance. A thin film, mainly composed of Ta2O5, formed on the surface of the tantalum coating, preventing the diffusion of substrate elements. The corrosion process and mechanism of Ta-316 were also examined.

Enhancing photocatalytic performance of regular porous silver bromide structures through 3D printing

This study introduces the innovative method of in-situ precipitation (ISP) 3D printing technology for fabricating photocatalyst structures capable of efficiently degrading water pollutants. The technology involves using silver nitrate aqueous solution to print directly on the surface of solidified NaBr aqueous solution, resulting in the formation of regular porous silver bromide structures. The structures are then densified through drying and sintering, followed by photoreduction using ultraviolet radiation to create Ag@(silver atom cluster)AgBr photocatalyst structures. Experimental results demonstrate the effectiveness of this photocatalyst structure in degrading azo dyes (Orange II) and eliminating Escherichia coli (E. coli) under visible light and ultraviolet light irradiation. The degradation of azo dyes and the sterilization of E. coli follow first-order kinetic reactions, with the photocatalyst module maintaining an 84.8% degradation rate after five recycling cycles. Complete elimination E. coli of the photocatalytic module is achieved within 120 min, and its sterilization effect follows a hyperbolic reaction. The study further confirms the durability and reusability of the photocatalyst structure, highlighting ISP 3D printing technology as a promising approach for fabricating efficient photocatalyst structures to address water pollution challenges in water treatment and environmental protection.

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing Trans / Cis Isomers

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing <i>Trans</i> / <i>Cis</i> Isomers

Fast Scalable Synthetic Methodology to Prepare Nanoflower‐Shaped Bi/BiOClxBr1−x Heterojunction for Efficient Immobilized Photocatalytic Reactors under Visible Light Irradiation

AbstractThe metal/photocatalyst heterojunction has demonstrated an excellent capability for pollutant degradation under visible light irradiation. In this study, for the first time, highly stable colloidal dispersions of Bi/BiOClxBr1−x heterojunction with an exposed (001) facet are successfully prepared from inorganic simple salts using low‐frequency ultrasound irradiation (LFUI) at ambient conditions without further post‐treatment. The colloidal dispersion series of Bi/BiOClxBr1−x heterojunction (x = 0, 0.2, 0.5, 0.8 and 1) is simply obtained by adding stoichiometric aqueous solutions of NaCl and NaBr, into an acidic aqueous solution of Bi(NO)3.5H2O in a typical ultrasonication bath at room temperature within ≈5 min. Bi/BiOClxBr1−x heterojunction films are also fabricated using a simple drop‐casting technique and tested as immobilized photocatalytic reactors. Compared to its counterparts, the Bi/BiOCl0.8Br0.2 film possesses a 3D flower‐like morphology with a highly exposed (001) facet showing the highest electron‐hole generation and separation efficiencies. In addition, the Bi/BiOCl0.8Br0.2 film demonstrates the highest photocatalytic degradation rate of the rhodamine RhB aqueous solutions (≈5 ppm), achieving ≈99% in 60 min under the visible light component of the solar spectrum. This study demonstrates the potential of LFUI as a rapid scalable synthetic strategy for cost‐effective and energy‐efficient practical production of highly active immobilized photocatalytic reactors.

Organic Compound Degradation Induced by Br Oxidation with O3 Fine Bubble Injection into Seawater

ABSTRACT An advanced technique for the utilization of the dissolved Br in concentrated seawaters discharged from the salt manufacturers in Japan can enable the development of a comprehensive utilization system for seawater resources. Hypobromous acid (HOBr) and hypobromite ion (BrO–) obtained by the oxidative reaction of Br– degrade the many organic compounds and can be utilized as water purification reagents with excellent decolorizing and disinfection capabilities. In this study, we focused on the production of Br oxyacid as an upgrading method for Br using O3 fine bubbles, which has a high oxidation potential, and developed a technique for water purification. When O3 fine bubbles are introduced into the liquid phase, the gas absorption of O3 is accelerated by the increases in gas–liquid interfacial area and residence time of the bubbles and the hydroxyl radical (OH•) generation is enhanced by the increase in contact probability between the dissolved O3 and accumulated OH– at the minute gas–liquid interfaces. Moreover, when O3 fine bubbles are supplied into a liquid phase with coexisting Cl– or Br– as halogen ions, further improvement in oxidation potential in the liquid phase can be expected by the acceleration of the Br oxyacid generation with OH•. When O3 fine bubbles with an average diameter of 50 µm were continuously supplied into the simulated seawater with pH value of 6.1 or ion-exchanged water with pH value of 5.6 at a constant solution temperature (T S) of 298 K, the concentration of active oxygen species (C OS) in the simulated seawater increased to 1.4 times higher than that in the ion-exchanged water. Additionally, in the case where O3 fine bubbles were injected into an aqueous solution of NaCl, MgCl2, CaCl2, KCl, or NaBr to ascertain the factor of C OS increment, the tendency of C OS to increase with the reaction time in the NaBr aqueous solution was more apparent than those in the ion-exchanged water and other salt aqueous solutions, because oxyacids of Br such as HOBr/BrO– were generated by the selective oxidation of Br– during the O3 fine bubble injection into the NaBr aqueous solution. Furthermore, to evaluate the effects of the Br– concentration on the degradation of methylene blue (MB) as an organic compound, MB was degraded by O3 fine bubble injection into NaBr/MB aqueous solutions with different initial NaBr concentrations. The formation of Br oxyacids owing to the acceleration of the reaction between O3 or OH• and Br− during the O3 fine bubble injection led to an enhancement in MB degradation.

Study of solute-solvent interactions using volumetric properties for the ternary {L-Serine +H2O+NaBr, KBr, LiBr} solutions at different temperatures and ambient pressure

Abstract Volumetric properties for L‑serine in aqueous LiBr, NaBr and KBr solutions, are reported by using the measured density values for these systems. The apparent molar volume at infinite dilution (Vφ0) is evaluated by fitting the Redlich-Meyer type equation to apparent molar volume values (Vφ). In the following, the expansibility and hydration number for L‑serine are appraised. The results revealed that, by increasing concentration and temperature, the apparent molar volume values enhanced for all solutions. It is indicated that the calculated hydration number for L‑serine increased by growing the salt concentration in studied solutions while decreased when rising the temperature. Also solute–solvent interactions are discussed in detail. It is shown that L‑serine has structure maker role in considered ternary solutions.

Two-dimensional infrared spectroscopy of aqueous solutions from first principles simulations

Vibrational spectral diffusion of OH/OD modes in liquid water can be influenced by the presence of ions, dipolar solutes or by the change of temperature. In the present work, we have calculated the two-dimensional infrared (2D-IR) spectrum of aqueous NaBr and urea solutions at room temperature and also liquid water at two different temperatures to study the effects of these solutes and varying temperature on the dynamics of vibrational spectral diffusion of OD stretch modes in aqueous media. Time-dependent evolution of the ellipticity of 2D-IR spectra is calculated to obtain timescales of the dynamics of vibrational spectral diffusion.

Dissolution of collagen fibers from tannery solid wastes in salt aqueous solutions: Hofmeister series evaluation

AbstractBACKGROUNDCollagen fibers from tannery solid wastes were treated with aqueous solutions of inorganic salts. The effect of the inorganic salts on the dissolution of collagen fibers and degradation of collagen were investigated. Tests of reduced viscosity and sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS‐PAGE) were applied to evaluate the degree of degradation during the dissolution process. The specific ionic effects of the Hofmeister series on the dissolution of collagen fibers in salt aqueous solutions were demonstrated.RESULTSAccording to all the results, the dissolution abilities of inorganic salts were in the order of Br− &gt; Cl− &gt; SCN− &gt; CH3COO− &gt; H2PO4− &gt; CO32− as well as Na+ &gt; Mg2+ &gt; Ca2+ &gt; NH4+ &gt; K+ &gt; Li+. The results indicated that NaBr aqueous solution could have potential ability as a solvent to dissolve collagen fibers without excessive degradation of collagen.CONCLUSIONSNaBr aqueous solution could have potential ability as a solvent to dissolve collagen fibers without excessive degradation of collagen. By analyzing the results of the reduced viscosity tests, SDS‐PAGE and amino analysis, proper dissolution conditions were evaluated with the conditions of NaBr aqueous solution concentration of 1 mol L−1, contacting time of 4 h and temperature of 60 °C. From amino analysis and in situ optical microscopy observation, a possible process of collagen fiber dissolution in NaBr solution was demonstrated. This work provides a method for treating and recycling tannery solid wastes with some information for the investigation of collagen‐based materials. © 2019 Society of Chemical Industry

Tailoring the stability/aggregation of one-dimensional TiO2(B)/titanate nanowires using surfactants.

The increased utilization of one-dimensional (1D) TiO2 and titanate nanowires (TNWs) in various applications was the motivation behind studying their stability in this work, given that stability greatly influences both the success of the application and the environmental impact. Due to their high abundance in aqueous environments and their rich technological applicability, surfactants are among the most interesting compounds used for tailoring the stability.The aim of this paper is to determine the influence of surfactant molecular structure on TNW stability/aggregation behavior in water and aqueous NaBr solution by dynamic and electrophoretic light scattering. To accomplish this, two structurally different quaternary ammonium surfactants (monomeric DTAB and the corresponding dimeric 12-2-12) at monomer and micellar concentrations were used to investigate TNW stability in water and NaBr. It was shown that TNWs are relatively stable in Milli-Q water. However, the addition of NaBr induces aggregation, especially as the TNW mass concentration increases. DTAB and 12-2-12 adsorb on TNW surfaces as a result of the superposition of favorable electrostatic and hydrophobic interactions. As expected, the interaction of TNWs with 12-2-12 was stronger than with DTAB, due to the presence of two positively charged head groups and two hydrophobic tails. As a consequence of the higher adsorption of 12-2-12, TNWs remained stable in both media, while DTAB showed an opposite behavior.In order to gain more insight into changes in the surface properties after surfactant adsorption on the TNW surface, a surface complexation model was employed. With this first attempt to quantify the contribution of the surfactant structure on the adsorption equilibrium according to the observed differences in the intrinsic log K values, it was shown that 12-2-12 interacts more strongly with TNWs than DTAB. The modelling results enable a better understanding of the interaction between TNWs and surfactants as well as the prediction of the conditions that can promote stabilization or aggregation.

Tunable Ag Micromorphologies Show High Activities for Electrochemical H2 Evolution and CO2 Electrochemical Reduction

Contaminate-free nanostructured Ag is prepared from electrochemical redox-treated Ag by two different potential pulses (DP and r-DP) in an NaBr aqueous solution. Agr-DP and AgDP from r-DP and DP, respectively, are easily tuned for their activities in the hydrogen evolution reaction (HER) favoring or selective CO2 reduction reaction (CO2RR). Agr-DP shows Pt-like HER activity in H2SO4 aqueous solution, and AgDP is capable of electrochemically reducing CO2 to CO with approximately 97.8% catalytic selectivity at a low overpotential of ∼0.25 V in NaHCO3 aqueous solution. The electrochemical signals for the first observed CO2•– intermediate adsorption (CO2ads•–) and HCO3– adsorption (HCO3–ads) in the selected NaClO4 aqueous solution were used to understand the possible role of HCO3– in CO2RR.

Relative permittivity in the electrical double layer from nonlinear optics.

Second harmonic generation (SHG) spectroscopy has been applied to probe the fused silica/water interface at pH 7 and the uncharged 11¯02 sapphire/water interface at pH 5.2 in contact with aqueous solutions of NaCl, NaBr, NaI, KCl, RbCl, and CsCl as low as several 10 μM. For ionic strengths up to about 0.1 mM, the SHG responses were observed to increase, reversibly for all salts surveyed, when compared to the condition of zero salt added. Further increases in the salt concentration led to monotonic decreases in the SHG response. The SHG increases followed by decreases are found to be consistent with recent reports of phase interference and phase matching in nonlinear optics. By varying the relative permittivity employed in common mean field theories used to describe electrical double layers and by comparing our results to available literature data, we find that models recapitulating the experimental observations are the ones in which (1) the relative permittivity of the diffuse layer is that of bulk water, with other possible values as low as 30, (2) the surface charge density varies with salt concentration, and (3) the charge in the Stern layer or its thickness varies with salt concentration. We also note that the experimental data exhibit sensitivity depending on whether the salt concentration is increased from low to high values or decreased from high to low values, which, however, is not borne out in the fits, at least within the current uncertainties associated with the model point estimates.

Specific Anion Effects on Na+ Adsorption at the Aqueous Solution-Air Interface: MD Simulations, SESSA Calculations, and Photoelectron Spectroscopy Experiments.

Specific ion effects of the large halide anions have been shown to moderate anion adsorption to the air-water interface (AWI), but little quantitative attention has been paid to the behavior of alkali cations. Here we investigate the concentration and local distribution of sodium (Na+) at the AWI in dilute (<1 M) aqueous solutions of NaCl, NaBr, and NaI using a combination of molecular dynamics (MD) and SESSA simulations, and liquid jet ambient pressure photoelectron spectroscopy measurements. We use SESSA to simulate Na 2p photoelectron intensities on the basis of the atom density profiles obtained from MD simulations, and we compare the simulation results with photoelectron spectroscopy experiments to evaluate the performance of a nonpolarizable force field model versus that of an induced dipole polarizable one. Our results show that the nonpolarizable force model developed by Horinek and co-workers (Chem. Phys. Lett. 2009, 479, 173-183) accurately predicts the local concentration and distribution of Na+ near the AWI for all three electrolytes, whereas the polarizable model does not. To our knowledge, this is the first interface-specific spectroscopic validation of a MD force field. The molecular origins of the unique Na+ distributions for the three electrolytes are analyzed on the basis of electrostatic arguments, and shown to arise from an indirect anion effect wherein the identity of the anion affects the strength of the attractive Na+-H2O electrostatic interaction. Finally, we use the photoelectron spectroscopy results to constrain the range of inelastic mean free paths (IMFPs) for the three electrolyte solutions used in the SESSA simulations that are able to reproduce the experimental intensities. Our results suggest that earlier estimates of IMFPs for aqueous solutions are likely too high.

Investigation of Surface Properties for Electrolyte Solutions: Measurement and Prediction of Surface Tension for Aqueous Concentrated Electrolyte Solutions

Surface tensions for aqueous NaCl, NaBr, NaI, KCl, KBr, and KI solutions have been measured at different temperatures and different concentrations. The liquid densities and activity coefficients for electrolyte solutions are modeled accurately with the ion-based statistical associating fluid theory (SAFT2). Besides, a new surface tension prediction model on the basis of the Gibbs thermodynamic method, coupled with ion-based SAFT2 is established, which is applied to predict the surface tension of aqueous concentrated salt solutions at different concentrations and temperatures. In this model, we derived the relationship between the activity coefficient and surface tension, and the activity coefficient can be calculated by ion-based SAFT2. The model is found to give accurate prediction for the surface tension of aqueous concentrated electrolyte solutions at different concentrations and temperatures with the parameter obtained at one fixed temperature.

Electrochemical bromination of late stage intermediates and drug molecules

Abstract Aromatic C H bromination is one of the applications of late stage functionalization that provides precursors for generation of radio-labelled compounds to support drug metabolism and pharmacokinetic (DMPK) studies or provide a “handle” for further functionalization to expand SAR studies without having to resort to de novo synthesis. Electrochemical aromatic bromination was attempted on late stage intermediates and drug molecules such as cytidine, uridine, Tenofovir, MK-4618, Sch48973 and MK-8457. The reactions were conducted under mild galvanostatic electrolysis condition in aqueous NaBr solution. The brominated products were obtained and converted to the corresponding tritium labelled products. Electrochemical methodology provides an alternative way to quickly generate aryl bromides of late stage intermediates or drug molecules that are very useful in drug discovery.

Hydration of Bromine Ions in Water

A mass spectrographic method electrospraying electrolyte solutions in vacuum was used to determine the enthalpy of hydration of bromine ions by different numbers of water molecules. The mass spectra of negative ions from aqueous solutions of NaBr were measured over the temperature range of 15–50°C and showed that the most intense peaks correspond to the hydrated bromine ions with one and two water molecules. It was found that the Van't Hoff equation holds for bromine hydrates containing up to three water molecules, whereas addition of the fourth water molecule leads to a violation of the Van't Hoff equation. The enthalpy of bromine ion hydration by the first and the second water molecules was found to be –(28.5 ± 1.7) and –(21 ± 4.2) kJ/mol, respectively.

Effect of Interparticle Interactions on Agglomeration and Sedimentation Rates of Colloidal Silica Microspheres.

The sedimentation half-times ts of initially monodisperse dispersions of 750, 505, and 350 nm silica microspheres were measured in water, in ethanol, and in aqueous NaBr solutions of concentration cNaBr ranging from 50 to 1000 mM, where the particles may have formed clusters. In water and in ethanol, ts was about 8, 18, and 33 h for the 750, 505, and 350 nm particles, respectively. These values were the same as the ones predicted by Stokes’ law, suggesting that the particles were monodisperse and remained so during sedimentation; ts values remained the same with increasing particle weight fraction up to 0.03, indicating no hydrodynamic interactions. Three regions of NaBr concentrations with different settling behavior were found for each size. In region I or at lower cNaBr, the ts values were the same as at no salt conditions, implying that there was no significant agglomeration before particles settled. In region II, ts decreased with increasing cNaBr, suggesting that the agglomeration and sedimentation ...

Chemiresistors based on ultrathin gold nanowires for sensing halides, pyridine and dopamine

Two distinctively different approaches to the deposition of the ultrathin gold nanowires (NWs) on chips for the development of the chemiresistor sensors are studied. The first approach is the deposition of the pre-synthesized NWs on a chip using a microfluidic technique, and the second is the direct synthesis of the NWs on chips. It is shown that the 2nd approach ensures a better contact between the NWs and electrodes, lower resistance of the NW sensor device, and a longer life time of the devices. The current-voltage dependencies obtained for the chips with the NWs in contact with air, and aqueous solutions of NaF, NaCl, NaBr, NaI, pyridine, and dopamine indicate significant changes of the NWs resistance caused by sorption of halides, pyridine and dopamine on the NWs surface. This change of the NWs resistance can be used for quantification of Cl− over a concentration range of 10−5–10−3M and dopamine over a concentration range of 10−8–10−5M. Tentatively, it is concluded that the data obtained can be explained in terms of the Langmuir adsorption isotherm.

Enthalpic pairwise self-association of l-carnitine in aqueous solutions of some alkali halides at T = 298.15 K

Knowledge of the influence of ions of various nature on intermolecular hydrophilic and hydrophobic interactions in solutions is required in many research fields. In this paper, dilution enthalpies of zwitterion l-carnitine in aqueous NaCl, KCl and NaBr solutions of various molalities (b=0 to 3.0mol·kg−1) have been determined respectively at T=(298.15±0.01)K and p=(0.100±0.005)MPa by isothermal titration calorimetry (ITC). In light of the MacMillan–Mayer theory, the 2nd virial enthalpic coefficients (h2) have been calculated. The h2 coefficients increase gradually with increasing molality (b) of the three aqueous alkali halides solutions, from small negative values in pure water to relatively larger positive values in solution. The trends of h2 coefficients are ascribed to the salt effects on the balance between hydrophilic and hydrophobic interactions in pairwise self-associations. It is considered that the size of cations and anions exert influences on h2 coefficients through their surface charge densities and hydration (or dehydration) abilities.

Quick measurement of continuous absorption spectrum in ion beam pulse radiolysis: Application of optical multi-channel detector into transient species observation

Abstract A quick measurement system of a continuous absorption spectrum covering a wide range from 200 to 950 nm was constructed by employing an optical multi-channel detector. Ion beam pulse radiolysis with 12.5 MeV/u He, 18.3 MeV/u C and 17.5 MeV/u Ne ions were performed with the measurement system. Transient absorption spectrum of ( S C N ) 2 • − was clearly observed in KSCN aqueous solutions within a few minutes in spite of their very small absorbance, demonstrating high sensitivity of 0.001–0.003 in absorbance in the range from 260 to 660 nm as well as short measurement time of a few minutes. Two different absorption peaks attributed to Br 2 • − and Br 3 − were observed simultaneously in NaBr aqueous solutions, showing powerfulness of the measurement system in overviewing chemical kinetics under ion beam irradiation especially in not well investigated chemical systems.

ChemInform Abstract: BiOClxBryIz (x + y + z = 1) Solid Solutions with Controllable Band Gap and Highly Enhanced Visible Light Photocatalytic Performances.

AbstractSingle phase BiOClxBryIz solid solutions with controllable band gap and highly enhanced visible light photocatalytic performance are prepared by hydrolysis of stoichiometric amounts of aqueous NaCl, NaBr, KI, and NaOAc solutions to which a Bi(NO3)3 solution in glacial AcOH is given.