NaBr Solution Research Articles

Corrosion mechanisms of Zr-based bulk metallic glasses in NaBr solution

In this paper, the corrosion mechanisms of Zr55Cu35Al10 and Zr56Co28Al16 bulk metallic glasses (BMGs) in 3.5 wt.% NaBr solution was systematically investigated by the kinetic potential polarization and electrochemical impedance spectroscopy. Both Zr55Cu35Al10 and Zr56Co28Al16 BMGs were subjected to pitting damage during the polarization process in NaBr solution due to the presence of Br− ions. However, Zr56Co28Al16 BMG exhibits better corrosion resistance compared to Zr55Cu35Al10 BMG. Zr55Cu35Al10 BMG experiences selective dissolution of alloying elements under the attack of Br−, and Cu element was enriched in the corrosion pit. The surface of Zr56Co28Al16 BMG shows a more uniform distribution of elements after corrosion. Simultaneously, the substitution of Cu by Co changes the composition of the passive films and increases the relative content of ZrO2, which is a principal factor contributing to the enhanced stability of Zr56Co28Al16 BMG's passive film.

Room‐Temperature Phosphorescence Hydrogel with Multiple Color Based on Salt‐Induced Aggregation

AbstractOrganic photoluminescent materials with room‐temperature phosphorescence (RTP) are of great interest, yet achieving RTP in hydrogels faces challenges due to water‐quenching effects. In this study, a straightforward method is presented to achieve RTP hydrogel using a self‐healing and salt‐hardening hydrogel. The hydrogel is synthesized by polymerizing acrylic acid (AA) with diethylenetriamine (DETA) as the dynamic crosslinker. The poly(acrylic acid)/DETA hydrogel could achieve an afterglow lasting 1.6 s after soaking with NaBr solution. The salt‐enhanced hydrophobic aggregation of the hydrogel network promotes the clustering of carboxyl groups and oxygen atoms, resulting in a rigid environment that suppresses nonradioactive transitions and leads to the manifestation of RTP. Additionally, the dynamic association of AA‐DETA allows the freeze‐dried hydrogel powder to be blended with various hydrophobic dyes, leading to a remodelable hydrogel with delayed emission of multiple colors. In general, by combining salt‐hardening property with self‐healing property together, a RTP hydrogel platform that can be facilely loaded with various organic dyes is proposed.

Reduction of bromate formation in electrochemical production of hypobromite for water disinfection

Hypohalites are powerful water disinfectants for many applications. Continuous production of hypobromite was studied using an undivided electrochemical cell operating at 20 A cell current (28.9 mA cm−2) and an electrolyte flow of 50 L h−1. With 34 mM NaBr as electrolyte current efficiency is between 25 and 42 %. Anodic oxidation and disproportionation of hypobromite led to formation of substantial concentrations of BrO3− in the electrolyte. BrO3− concentrations up to 1 mM (22.6 mg L−1) were formed during anodic Br− oxidation. Replacement of NaBr by mixtures of NaCl and NaBr as electrolyte led to reduction of BrO3− concentration to 0.5 mM (11.3 mg L−1). By combination of NaCl electrolysis with following dosage of NaBr solution the BrO3− concentration could be reduced below the detection limit of the analytical method which was used to quantify BrO3− and hypobromite. In a freshly prepared 5 mM hypobromite solution the BrO3− concentrations remained below 0.1 mM (2.2 mg L−1). When applied in typical dosage for halogen based disinfectants (10−3 mM and 10−2 mM hypohalite) the BrO3− concentration dilutes to 0.02 μM – 0.2 μM. The optimised process thus leads to BrO3− concentrations below the legal limit for BrO3− in drinking water (10 μg L−1 BrO3−).

A monovalent selective anion exchange membrane made by poly(2,6-dimethyl-1,4-phenyl oxide) for bromide recovery

Bromide recovery from waste streams is crucial for both environmental and economic reasons. Membrane technology has shown great potential in achieving efficient ion separation, credited to the use of separation membranes with well-defined pore structure down to molecular level and surface charge properties. Herein, a class of novel anion exchange membranes (AEMs) was fabricated by brominated poly (2,6-dimethyl-1, 4-phenyl oxide) (BPPO) and different content of 4-hydroxy-1-methylpiperidine (HMP) via the chemical substitution reaction for Br- recovery. The resulting membrane (HMP@BPPO-0.1) had an ion exchange capacity of 1.69 mmol g−1, a water content of 14.4 %, a swelling rate of 4.7 %, a surface electrical resistance of 3.68 Ω cm2 and a limiting current density of 28.4 mA cm−2. In addition, under a constant voltage of 15.0 V for 180 min in electrodialysis, the removal ratio of NaBr solution was 98.15 %, which was higher than that of the commercial AEM (ASE) (97.1 %) under the same testing conditions. To evaluate the Br- selectivity, the membranes were tested for an initial concentration of 50 mM of NaCl, NaBr and Na2SO4 in a mixed solution with a constant current density of 2.5 mA cm−2, 5.0 mA cm−2 and 10.0 mA cm−2. The results showed that the permselectivity of the HMP@BPPO-0.1 for 100 min was as high as 12.6 (Br-/SO42-) and 1.20 (Br-/Cl-) under the 5.0 mA cm−2 electric field, and the ion permeation rate of Cl-, Br- and SO42- were 0.78, 1.20 and 0.20 mol−1 m-2 h−1, respectively. Compared to the ASE membrane and the resulting membrane with negatively charged modification layer, this work suggests novel ideas in fabricating a membrane with Br- selectivity in view of resource recovery.

A key factor in determining the effectiveness of etchants for electrochemical surface enlargement of Ta foil for electrolytic capacitor

For electrochemical etching, it is often assumed intuitively that the high specific surface area (SSA) is largely dependent on the aggressiveness of the corrosive agent. Today, however, we present a different perspective. In this study, we combine theoretical calculations and electrochemical experiments to fully understand the mechanisms of Cl- and Br- in the three stages of the tantalum (Ta) pitting process, including passivation film breakdown, Ta anodic dissolution and re-passivation. The results show that both Cl- and Br- cause the breakdown of the passivation film and the dissolution of Ta atoms, with the former having a more pronounced effect. However, MD simulations show that the re-passivation of Ta occurs only in Br- containing media but not in Cl- containing media. This means that Ta is protected by adsorption of dissolved oxygen while being destroyed by Br-, but is only dissolved in NaCl solution. The same result is observed in our electrochemical experiments. In addition, the specific capacity of etched Ta foil in NaBr solution is as high as 325μF/cm2 while it is only 48μF/cm2 in NaCl. It is precisely the protective rather than the destructive effect of the etchant that is more important for obtaining high SSA.

Swelling poly(ionic liquid)s for demulsifying oil‐in‐water emulsion by anion exchange

AbstractIn this work, poly(ionic liquid)s (PILs) with swelling ability were prepared via the free radical copolymerization of N‐vinyl imidazolium ionic liquids and divinylbenzene. Nuclear magnetic resonance and Fourier‐transform infrared analyses confirmed the successful synthesis of PILs. The PILs were evaluated as demulsifiers for a model oil‐in‐water emulsion, where sodium dodecyl sulfate (SDS) was used as a surfactant. The demulsification efficiencies of PILs increased from 18%, 34%, 92% to 99% with the alkyl chain of three‐substituents on imidazolium varied from n‐octyl, n‐hex1yl, n‐butyl to n‐ethyl, which positively related with the swelling ratios of PILs in the emulsion. The amounts of dodecyl sulfate and Br− in the aqueous phase after demulsification were analyzed by high‐pressure liquid chromatography and ion chromatography, respectively. The decreased amount of dodecyl sulfate coincided with the increased amount of Br−, indicating that the anion exchange between surfactant SDS and PILs was occurred. The PILs could be recycled by ion exchange with NaBr solution and the demulsification efficiencies did not show significant decline during five times of recycling. Meanwhile, P[VEIm]Br@4 Å zeolite prepared by loading poly(1‐vinyl‐3‐ethylimidazolium bromide) on 4 Å zeolite was used for continuous demulsification in the T type device. The T type device had stable fluxes (1083 L ·m−2 h−1) for various oil‐in‐water emulsions with excellent demulsification efficiencies (above 99%).

The Effect of the Corrosion Medium on Silane Coatings Deposited on Titanium Grade 2 and Titanium Alloy Ti13Nb13Zr.

The present paper focuses on the fabrication of coatings based on vinyltrimethoxysilane and the influence of various corrosion media on the coatings produced. Coatings were deposited on two substrate materials, namely, titanium Grade 2 and titanium alloy Ti13Nb13Zr, by immersion in a solution containing vinyltrimethoxysilane, anhydrous ethyl alcohol, acetic acid and distilled water. The obtained coatings were characterized in terms of surface morphology, adhesion to the substrate and corrosion resistance. As corrosion solutions, four different simulated physiological fluids, which differed in the contents of individual ions, and a 1 mol dm−3 NaBr solution were used. The chloride ions contained in the simulated physiological fluids did not lead to pitting corrosion of titanium Grade 2 and titanium alloy Ti13Nb13Zr. This investigation shows that titanium undergoes pitting corrosion in a bromide ion medium. It is demonstrated that the investigated coatings slow down corrosion processes in all corrosion media examined.

Surface Chemistry of Gold Nanoparticles Produced by Laser Ablation in Pure and Saline Water.

Pulsed laser ablation in liquid (PLAL) is a powerful method for producing nanoparticle colloids with a long-term stability despite the absence of stabilizing organic agents. The colloid stability involves different reactivities and chemical equilibria with complex ionic-specific effects at the nanoparticle/solvent interface which must be strongly influenced by their chemical composition. In this work, the surface composition of PLAL-produced gold nanoparticles in alkaline and saline (NaBr) water is investigated by X-ray photoelectron spectroscopy on free-flying nanoparticles, exempt from any substrate or radiation damage artifact. The Au 4f photoelectron spectra with a depth profiling investigation are used to evaluate the degree of nanoparticle surface oxidation. In alkaline water, the results preclude any surface oxidation contrary to the case of nanoparticles produced in NaBr solution. In addition, the analysis of Br 3d core-level photoelectron spectra agrees with a clear signature of Br on the nanoparticle surface, which is confirmed by a specific valence band feature. This experimental study is supported by DFT calculations, evaluating the energy balance of halide adsorption on different configurations of gold surfaces including oxidation or adsorbed salts.

An optimized procedure for extraction and identification of microplastics in marine sediment

Microplastics (MPs) in sediment environments have been widely reported. As the number of samples increases, establishing a reliable and effective method becomes increasingly urgent for the rapid extraction and identification of MPs in sediments. Herein, we proposed a system with continuous density flotation of NaBr-ZnCl2 (mixture of NaBr and ZnCl2) solution for extracting MPs in a sediment sample, combined with micro-Fourier transform infrared (μ-FT-IR) imaging scanning for identification of MPs. The recoveries of MPs were estimated for four different sizes, shapes, and ten different types of polymers. The results indicated NaBr-ZnCl2 solution showed a high recovery rate from 88.33% to 100.00% for extracting these different MPs. The μ-FT-IR imaging scanning allows for the detection of plastic down to the size of 6.25 μm in filed samples, and merely takes about 3 min, which was validated by testing of sediments from Jiaozhou Bay, China and its adjacent estuaries.

A commonly available and easily assembled device for extraction of bio/non-degradable microplastics from soil by flotation in NaBr solution

Soil microplastic pollution has caused widespread research attention worldwide. It is necessary to efficiently separate microplastic particles from soil matrixes in order to conduct studies of microplastic. And so far, few studies have described the separation and extraction devices of biodegradable microplastic. Here we present a commonly available device for extraction of non-degradable and biodegradable microplastics from soil samples in a NaBr solution based on density flotation. The device has a combined circulation and recovery system for the salt solution, which increases its environmental-friendliness. The accuracy and precision of the device was verified through spike and recovery experiments using three types of biodegradable microplastics (PBS, PBAT, PLA) and four types of non-degradable microplastics (LDPE, PS, PP, PVC), all with different particle sizes, and all microplastics are grinded autonomously, closer to reality. In despite of differences in particle size and density, for both biodegradable and non-degradable microplastics the device exhibited good extraction precision, with recovery rates ranging from 92% to 99.6%, over a wide range of particle densities and sizes. The recovery rates slightly increased with increased polymer density and microplastic particle size.

Fusing of Silver Nanoparticles at Room Temperature Using Halide Solutions for Conductive Inks

Fusing of silver (Ag) nanoparticles synthesized in an aqueous system was observed at room temperature using halide solutions. The as-synthesized Ag nanoparticles have an average diameter of about 24 nm. After dispersing the Ag nanoparticles in a halide solution, a significant increase in particle size to about 188-197 nm was observed. The enlargement of particle size was accompanied by the increase in conductivity of the Ag nanoparticle ink. The resistance was reduced from 110 kiloohms to 35 and 9.3 ohms for the as-prepared and sintered Ag nanoparticles using NaBr and NaCl solution, respectively.

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− > Cl− > SCN− > CH3COO− > H2PO4− > CO32− as well as Na+ > Mg2+ > Ca2+ > NH4+ > K+ > 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

Experimental investigation of assessment of the contribution of heterogeneous semi-confining shale layers on mixing and trapping of dissolved CO2 in deep geologic formations

In most conceptual models of dissolution trapping of CO2, it is assumed that mixing of dissolved supercritical CO2 and formation brine occurs through density-driven convection. In our previous modeling study, we showed that the presence of continuous low-permeability shale layers in the formations causes convective shutdown through disruption of fingers, which impacts the effectiveness of mixing and trapping processes. However, these layers are naturally heterogeneous due to variations in compositional and textural properties. In the present study, we investigate the potential effects of heterogeneity present within semi-confining low-permeability layers on the overall mixing and trapping of dissolved CO2. Since accurate field experimentation in deep geologic formations is difficult due to inability to adequately characterize geology and define boundary conditions of the formation, we designed well-controlled experiments using NaBr solution and water under laboratory conditions. We conducted intermediate-scale 3D laboratory experiments under two homogeneous and one heterogeneous multilayered sand packing configurations. The results of these experiments show that connectivity of relatively higher permeability material within the semi-confining low-permeability layers contributes to mixing through (1) brine leakage between upper and lower aquifers (reverse convection), and (2) trapping through diffusion and back diffusion of initially trapped mass due to reversed concentration gradients in the long term. These findings suggest that when estimating the effectiveness of dissolution trapping in CO2 sequestration one needs to consider possible deviations from the traditional convective mixing theory in homogeneous media. Under some conditions of natural formation heterogeneity, diffusion can contribute to trapping; in some others, it may not.

Rapid and Sensitive Surface-enhanced Raman Spectroscopy Method for Determination of Ketamine in Urine.

Surface-enhanced Raman spectroscopy (SERS) has gradually proved to be a powerful tool with wide applications in various fields. Here, a simple and rapid SERS method was developed for the determination of ketamine in urine based on silver aggregates as a SERS substrate. Ketamine in urine were demonstrated by the SERS technique with silver sol aggregated by a 0.5 M NaBr solution. The limit of detection for ketamine in urine could be obtained as low as 7.5 ppm, and a linear relationship for ketamine in urine between the Raman intensity and the concentrations was achieved in the range from 7.5 to 150 ppm (R2 = 0.977). Additionally, the recovery of this method ranged from 95.7 to 104.9%, which laid a favorable foundation for the rapid and reliable quantitative detection of ketamine in urine. Therefore, this SERS approach with high sensitivity and simplicity has a great prospect for the real-world application of ketamine in urine.

A method for extracting soil microplastics through circulation of sodium bromide solutions.

Microplastics (MP) have been recently found in soil environments. These MP might have adverse effects at high concentrations and thus efficient extraction and analysis of MP from soil is needed. Here we propose a new method of NaBr solution circulation for extracting soil MP. A device for the circular extraction of soil MP was developed. This device included a separation, vacuum filtration, and solution recovery system. It was then utilized to test separation efficiency of soil MP with three economic and environmentally friendly extraction reagents: NaCl, CaCl2 and NaBr solutions. The separation was tested with ten different types of polymers, three different size classes and three different shapes of MP. Extraction with NaBr showed the highest recovery rates ranging from 85% to 100%. After extraction the samples were treated with H2O2 and analyzed by micro-Fourier transform infrared spectroscopy. The developed method was assessed for its potential influence on MP and no significant changes in the integrity of multiple MP were found. Finally, the established method was used to analyze MP in four types of soil: farmland, yellow-brown, paddy and floodplain soil from the suburb of Shanghai. Results showed that the mean abundance of MP was 136.6-256.7 item kg-1. Various MP including PP (40%), PE (35.5%), Acrylic (15.6%), PET (6.7%) and PA (2.2%) were found. With this paper, we provide an alternative method through NaBr solution circulation for the extraction of soil MP.

Activity Coefficient of Bromide Ions in the Glucoamylase Solution

In this work, the electrodynamic potential E of the sodium bromide (NaBr) solution and tetrabutyl-ammonium bromide (TBAB) solution in the presence of glucoamylase was determined with an ion selective electrode at 278.15, 288.15, and 298.15 K. In addition, the value of activity coefficient of bromide ions at three temperatures was calculated with the Debye–Huckel equation and Pitzer equation. The results showed that the maximum relative error of activity coefficient of bromide ions calculated by the two methods was 8.63%. The activity coefficient of bromide ions in the NaBr solution decreased with increasing molality of NaBr, and the activity coefficients of bromide ion first decreased and then increased with increasing molality of TBAB. The concentration of glucoamylase had different effects on the relationship between the activity coefficient of bromide ions and electrolyte concentration at different temperatures. The value of the activity coefficient of bromide ions in the TBAB solution was greater than...

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.

Effect of annealing temperature on pitting behavior and microstructure evolution of hyper‐duplex stainless steel 2707

AbstractHyper‐duplex stainless steel (HDSS) 2707 is a competitive material for application in extremely caustic environments. In this study, different annealing temperatures ranging from 1020°C to 1200°C were examined by electrochemical tests and microstructure analysis. The microstructure characterization indicated that precipitations were detected when the annealing temperature was below 1050°C and a relatively balanced austenite–ferrite phase structure was obtained at 1100°C. Through electrochemical measurements in NaBr solution, it was revealed that with the increase of temperature the pitting resistance of HDSS 2707 first rose then declined, peaking at 1100°C. The highest critical pitting temperature was about 67°C. In addition, the pitting position shifted from austenite phase to austenite–ferrite boundary and finally to ferrite interior with the annealing temperature increasing, which was in agreement with the pitting resistance equivalent values (PREN) of the two phases.

The Contrast between the Pitting Corrosion of 316 SS in NaCl and NaBr Solutions: Part II. Morphology, Chemistry, and Stabilization of the Pits

This paper intends to evaluate the pit chemistry characteristics of 316 austenitic stainless steel in NaCl and NaBr solutions while discussing the pitting transition from metastability to stability. Results reveal that increasing the relative concentration of bromide increases the critical and saturation concentrations of cations, which are, respectively, requisites for pit survival and salt precipitation. Besides, bromide causes the ohmic solution resistance of the pit solution to increase. Consequently, it intensifies the pit transition from metastability to stability and retards the occurrence of the stable pitting. The morphology of the pits and the influence of the pit lacy cover on the pit stabilization in NaCl and NaBr solution are also discussed. It was also observed that contrary to metastable pits, salt-covered stable ones have higher growth kinetics in the presence of bromide.

Electrochemical micromachining behavior on 17-4 PH stainless steel using different electrolytes

Abstract The microtextured surfaces are used to improve the efficiency of engineering components like aerospace, biomedical, tribology, defense, etc. Electrochemical micromachining (ECMM) is a more promising technique for fabrication of microtextured surfaces because of its advantages like high material removal rate, less energy require, less space and tool-material wastage over other methods. 17-4 PH SS alloy is a precipitation hardened (PH) martensitic grade of stainless steel (SS) used in the field of aerospace for making turbine blades, power plant, marine and chemical industry. Properties such as high tensile and fatigue strength, good toughness, high hardness and formability make its machinability inferior. ECMM behavior of 17-4 PH SS alloy is completely unfamiliar. Since, there is no information available on the suitability of electrolyte dissolution with 17-4 PH SS while using ECMM, the present study aims to provide a suitable electrolyte for microfabrication on 17-4 PH SS alloy using ECMM with tungsten carbide for achieving better surface integrity. Electrolytes used for ECMM are aqueous solution of NaBr and combined aqueous solution of NaCl+NaNO 3 . The performance characteristics such as radial overcut, material removal rate (MRR), dimple depth and some aspects of surface integrity have been investigated. Owing to non-passivating behaviour of NaBr electrolyte, it actively participate with 17-4 PH SS alloy and results in overcuts and pits on the surface. The better dimensional accuracy and surface integrity have been achieved with NaCl+NaNO 3 electrolyte.