NaBr Solutions 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.

Thermodynamic Modeling of Methane Hydrate Phase Equilibria in Chloride and Bromide Solutions

The formation of hydrates is a major issue in the oil and gas industry. Injection of electrolytes is considered one of the best ways to prevent its formation. A thermodynamic model is developed from the Klauda and Sandler model, PRSV EoS, and Pitzer’s correlation to study the phase equilibria of methane hydrate in chloride and bromide electrolyte solutions. The model employs the parameters reported by Pitzer and Mayorga to calculate the Debye–Huckel coefficient and the second and third virial coefficients at 25 °C. The %AAD in predicted equilibrium pressures from experiments is 3.70 when the hydrate formed in NaCl, KCl, MgCl2, and CaCl2 solutions, whereas it is 2.33 in NaBr, KBr, MgBr2, CaBr2, and ZnBr2 solutions. The inhibition effect of any electrolyte on methane hydrate formation at 1 wt % is small, slowly increases at 3 wt %, and then pronounces at 5, 10, and 15 wt %. The cage occupancies have been found to increase and the activity of water has been found to decrease with the increase in electrolytes concentration. The freezing point depression of water in the presence of the strongest inhibitor MgCl2 has been observed to be −12.82 °C, whereas in the presence of the weakest inhibitor ZnBr2 it is −4.22 °C, both at 15 wt % concentration. Based on the phase equilibrium results and the freezing point depression of water, the order of the methane hydrate inhibition effect among all of the electrolytes studied here is MgCl2 > NaCl > CaCl2 > KCl > NaBr > ZnCl2 > MgBr2 > KBr > CaBr2 > ZnBr2.

Whole wheat flour enriched with nectarine powder - antioxidant activity, microbiological and moisture sorption characteristics

The aims of the current scientific study are to present the initial data research on the flour mixture of whole wheat flour enriched with nectarine powder of Bulgarian origin – intended for sponge cake production - was created. The natural content of the antioxidants was evaluated through the in vitro methods DPPH, ABTS, FRAP, and CUPRAC. The equilibrium moisture content (EMC) and monolayer moisture content (MMC) were investigated at 10°C, 25°C, and 40°C, resembling the diapason of temperature conditions in the storage house. The water activity (from 0.1 to 0.9) is provided through saturated salt solutions of LiCl, CH3COOK, MgCl2, K2CO3, MgNO3, NaBr, NaCl, and KCl. The obtained adsorption and desorption EMC declare the tendency – with its increase, the temperature decrease at the constant value of aw. According to Brunauer’s classification, sorption isotherms are of the second class, showing their characteristic S-shape profile. The modeling of the obtained sorption data includes their mathematical description using one of the three-parametrical models of modified Halsey, Oswin, Chung-Pfost, and Henderson. The Brunauer-Emmett-Teller linearization was presented to the values of the monolayer moisture content – for the adsorption process they are between 5.78% and 8.94%; and for the desorption - between 7.25% and 8.89%.

Water sorption isotherms on lyophilized jabuticaba (Myrciaria cauliflora) peel: potential byproduct for the production of dehydrated foods.

In this work, water sorption profiles on lyophilized jabuticaba peel were evaluated using the BET, GAB, Halsey, Henderson, Oswin and Smith isotherm models. All water sorption studies were conducted using the static gravimetric method and saturated CH3COOK, K2CO3, NaBr, SnCl2, KCl and BaCl2 solutions at 20, 30 and 35°C. The best water sorption isotherm fits were determined with the GAB model at 20°C, Oswin model at 30°C and Halsey model at 35°C. The curve profiles of the isotherm models employed were classified as type III. The results revealed that lyophilized jabuticaba peel can be safely stored at 20, 30 or 35°C with the monitoring and control of relative humidity, equilibrium humidity and water activity. However, microbial action and undesirable enzymatic reactions may occur at 35°C when the relative humidity is above 22%. The present results are useful for defining suitable storage and production conditions of a novel jabuticaba peel-based process for the production of dehydrated foods.

Probing electrolyte-silica interactions through simulations of the infrared spectroscopy of nanoscale pores.

The structural and dynamical properties of nanoconfined solutions can differ dramatically from those of the corresponding bulk systems. Understanding the changes induced by confinement is central to controlling the behavior of synthetic nanostructured materials and predicting the characteristics of biological and geochemical systems. A key outstanding issue is how the molecular-level behavior of nanoconfined electrolyte solutions is reflected in different experimental, particularly spectroscopic, measurements. This is addressed here through molecular dynamics simulations of the OH stretching infrared (IR) spectroscopy of NaCl, NaBr, and NaI solutions in isotopically dilute HOD/D2O confined in hydroxylated amorphous silica slit pores of width 1-6nm and pH ∼2. In addition, the water reorientation dynamics and spectral diffusion, accessible by pump-probe anisotropy and two-dimensional IR measurements, are investigated. The aim is to elucidate the effect of salt identity, confinement, and salt concentration on the vibrational spectra. It is found that the IR spectra of the electrolyte solutions are only modestly blue-shifted upon confinement in amorphous silica slit pores, with both the size of the shift and linewidth increasing with the halide size, but these effects are suppressed as the salt concentration is increased. This indicates the limitations of linear IR spectroscopy as a probe of confined water. However, the OH reorientational and spectral diffusion dynamics are significantly slowed by confinement even at the lowest concentrations. The retardation of the dynamics eases with increasing salt concentration and pore width, but it exhibits a more complex behavior as a function of halide.

Study of the aggregation, interaction, and thermodynamic properties of the dodecyltrimethylammonium bromide & cefixime trihydrate mixture in sodium salts solution at numerous temperatures

Cefixime trihydrate (CMT) has the usages to treat the bacterial infections of urinary tract, throat, ear & tonsils. Herein, the current investigation describes the interaction of CMT with dodecyltrimethylammonium Bromide (DTAB) by means of the conductivity measurement method in H2O and aq. solutions of NaBr, Na2SO4, and Na3PO4. The experiments were carried out at 310.55 K for several concentrations of CMT/ salts and temperatures of 300.55−320.55 K for one particular concentration of CMT/ salts employed. In every case, a single critical micelle concentration (CMC) has been achieved. The addition of CMT augments the aggregation of DTAB. The CMC values of the DTAB + CMT mixture undergo a decrease in attendance of electrolytes in comparison to water medium. In the manifestation of electrolytes, the CMC values of DTAB + CMT mixed systems at 310.55 K and ionic strength of 1 mmol kg−1 follow the order: CMC (H2O + NaBr) > CMC (H2O + Na2SO4) > CMC (H2O + Na3PO4). The negative ΔG°m values indicated that the micellization of DTAB + CMT mixture was spontaneous. The -ΔH°m and +ΔS°m values disclose that the assembly of DTAB + CMT mixture in aqueous medium is both enthalpy & entropy-controlled process. The thermodynamics of transfer and enthalpy-entropy compensation have also been described in the ongoing study.

Surface complexation reactions in sandy porous media: Effects of incomplete mixing and mass-transfer limitations in flow-through systems

Although mixing and surface complexation reactions are key processes for solute transport in porous media, their coupling has not been extensively investigated. In this work, we study the impact of mass-transfer limitations on heterogeneous reactions taking place at the solid-solution interface of a natural sandy porous medium under advection-dominated flow-through conditions. A comprehensive set of 36 column experiments with different grain sizes (0.64, 1.3 and 2.3 mm), seepage velocities (1, 30 and 90 m/day), and hydrochemical conditions were performed. The injection of NaBr solutions of different concentrations (1–100 mM) led to the release of protons via deprotonation reactions of the quartz surface. pH and solute concentration breakthrough curves were measured at the outlet of the columns and the propagation of pH fronts in the column setups was tracked inside the porous medium with non-invasive optode sensors. The experimental results show that the deprotonation of the reactive surfaces, resulting from their interactions with the injected ionic species, strongly depends on the hydrodynamic conditions and differs among the tested porous media despite their apparent similar surface properties. Reactive transport modeling was used to quantitatively interpret the experimental results and to analyze the effects of mass-transfer limited physical processes on surface complexation reactions, propagation of pH fronts, transport of major ions and spatio-temporal evolution of surface composition. A dual domain mass transfer formulation (DDMT) combined with a surface complexation model (SCM) allowed capturing the effects of incomplete mixing on the surface reactions and to reproduce the experimental observations collected in the experiments with high flow velocities. The SCM was parameterized with a single set of surface complexation parameters, accounting for the similar surface properties of the porous media, and was capable of describing the surface complexation mechanisms and their impact on the hydrochemistry over the large range of tested ionic strengths.

Simultaneous determination of monochloropropanediol esters and glycidyl esters in vegetable oils by acidic transesterification-gas chromatography-mass spectrometry

建立了一种气相色谱-质谱同时测定植物油中3-氯丙二醇酯、2-氯丙二醇酯和缩水甘油酯的方法。称取0.25 g样品,依次加入内标工作液、四氢呋喃和酸性溴化钠溶液,50 ℃水浴反应15 min,加入6 g/L碳酸氢钠溶液终止反应,使用正己烷提取,上层液经氮气吹干后用四氢呋喃溶解。随后加入1.8%(v/v)硫酸-甲醇溶液于40 ℃恒温水浴中反应16 h,加入饱和碳酸氢钠溶液终止反应。样液再经过净化、衍生、提取、氮吹后,以1 mL正己烷定容,过膜,进样测定。采用毛细管气相色谱柱DB-5MS(30 m×0.25 mm×1 μm)分离,程序升温,电子轰击电离(EI)源检测,在选择离子扫描模式下,以保留时间和特征离子信息进行定性分析,内标法定量。结果表明,3-氯丙二醇酯、2-氯丙二醇酯和缩水甘油酯在0.01~0.80 mg/L范围内线性关系良好,相关系数(r2)均在0.999以上,方法的检出限(S/N=3)和定量限(S/N=10)分别为25、25、20 μg/kg和75、75、60 μg/kg。选取4种不同基质类型的样品,在低、中、高3个不同添加水平下的平均回收率为89.0%~98.7%,相对标准偏差(RSD)在2.05%~7.81%之间。采用该方法测定了市售112份植物油样本,其中有84份样本检出3-氯丙二醇酯、2-氯丙二醇酯和缩水甘油酯。与已建立的国家标准方法(GB 5009.191-2016)和行业标准方法(SN/T 5220-2019)相比,该方法所采用的酸性酯交换法可避免副反应(碱性条件下3-氯丙二醇、2-氯丙二醇及3-溴丙二醇向游离态缩水甘油转化)的发生,同时该方法也弥补了国家标准和行业标准无法对3-氯丙二醇酯、2-氯丙二醇酯和缩水甘油酯同时进行测定的缺失。该方法实验操作更高效,结果更准确、重复性更好,对我国植物油中3-氯丙二醇酯、2-氯丙二醇酯和缩水甘油酯污染水平的控制、检测标准的制定和生产工艺的优化具有一定的理论和现实意义。

Synthesis of the S/AgBr nano/micropowder in DMSO-water system

A new synthesis method of S/AgBr nano/micropowder based on sulfur and silver halide was developed. The nano/micropowder was obtained in the DMSO-water system, in two stages. Initially, sulfur was dissolved in DMSO at 120°C. The resulting solution was cooled to room temperature and separated from sulfur by filtration. Then, pre-prepared water solutions of AgNO3 and NaBr were introduced drop by drop into a sulfur solution in DMSO, at room temperature. The phase composition and structure of the precipitated powdery sediment were studied by X-ray diffraction analysis (XRD) and Raman spectroscopy. Scanning electron microscopy (SEM) was used to study the morphology and particle size. XRD showed the presence of the crystalline phase of AgBr, while the Raman spectra were characterized by the presence of sulfur and AgBr peaks. The SEM results showed that the S/AgBr is represented by oval, spherical and triangular particles of a homogeneous structure; the particle size was in the range from 300 to 800 nm.

Suitability of electrolytes and anodic dissolution behavior of 17-4 PH stainless steel

17-4 PH SS alloy finds widespread applications in turbine blades, power plants, marine and chemical industries. However, some of its mechanical properties such as high tensile and fatigue strength, good toughness, high hardness and formability make its machinability poor. Thus, non-conventional machining processes such as electrochemical micromachining (ECMM), which removes the material by chemical dissolution, has better potential to fabricate micro features of high surface quality. However, the ECMM behavior of 17-4 PH SS alloy has not been exhaustively explored yet. It is very important to understand the regular dissolution patterns to improve machining stability and machined surface quality. Therefore, the present work aims at studying the suitability of different electrolytes in ECMM process for the fabrication of micro features with better dimensional accuracy and surface quality on 17-4 PH SS alloy. The electrolytes used in the experimentation are an aqueous solution of NaBr, NaCl, NaNO3and a compound aqueous solution of NaCl + NaNO3. The performance characteristics such as radial overcut, dimple depth and some aspects of surface integrity have been investigated. Experimental results showed that better dimensional accuracy and surface quality have been achieved with NaCl + NaNO3electrolyte owing to the combined properties of passive and non-passive electrolytes.

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.

Isotherm moisture sorption of composite desiccant made from rice husk biomass

The behavior of isotherm moisture sorption form rice husk-CaCl2 composite desiccants was studied. The desiccant composite in various treatments was tested for its isotherm sorption using gravimetric method. Saturated solution of LiCl, CH3COOK, MgCl, K2CO3, NaBr, NaNO2, NaCl, KCl, and K2SO4 were used to obtain the moisture of 11 %, 22 %, 32 %, 44 %, 56 %, 64 %, 75 %, 84 % and 97 %. Water activity produced from these saturated salt solutions was measured using aw meter. The equilibrium moisture data was then fitted into several isothermal equation models that have been used and tested in several literature including the model of Courie, Oswin and Chen Clayton. This rice husk composite desiccant had exposed a J shape curve of equilibrium water content with a boundary zone A of aw 0.2 and zone B of aw 0.67. Based on the isothermic absorption curve, the Oswin equation model was able to predict the results of research with R2 of 0.96, 0.89 and 0.97, respectively for temperature of 30, 40 and 50°C. This rice husk desiccant was able to absorb water vapor at low RH. It means that this desiccant is promising to be used for low water content or hygroscopic product such as flour based product, food flavor powder, chili powder, palm sugar and other products.

Effects of bromide adsorption on the direct synthesis of H2O2 on Pd nanoparticles: Formation rates, selectivities, and apparent barriers at steady-state

The direct synthesis reaction (H2 + O2 → H2O2) may provide a low-cost method to form H2O2 if catalytic systems with sufficient selectivities and stabilities are developed. Here, we examine how sodium bromide, a ubiquitous promoter for direct synthesis, impacts steady-state rates and apparent barriers for H2O2 and H2O formation in water and relate changes to the effect of NaBr on surface and bulk properties of Pd nanoparticle catalysts. Comparisons of turnover rates and selectivities measured over an extended period (>80 h) demonstrate that these systems require more than 10 h to reach steady-state, whereupon, H2O2 selectivities depend strongly upon [NaBr] and increase from 17% in pure water to ~65% at 10−4 M NaBr (55 kPa H2, 200 kPa O2). Contact with these NaBr solutions irreversibly modifies Pd nanoparticles, such that H2O2 selectivities remain at 40% in pure water, due to irreversible uptake of Br*-atoms. Bromide adsorption isotherms measured show that reduced Pd nanoparticles adsorb several monolayers of Br*-atoms, which suggests Br saturates surfaces but also resides within the near-surface region of Pd nanoparticles. Ex situ X-ray photoelectron spectroscopy indicates that Br*-atoms withdraw charge from Pd atoms and yield greater fractions of Pd2+. Comparisons among infrared spectra of adsorbed CO imply that persistent Br atoms preferentially bind to undercoordinated sites. H2O2 and H2O formation rates, both in the presence and absence of Br*-atoms, change with H2 and O2 pressures in ways consistent with elementary steps that involve H2O-mediated proton-electron transfer (PET). Therefore, increased selectivities on Br*-modified surfaces reflect differences in apparent activation enthalpies for H2O2 (ΔH‡H2O2)and H2O (ΔH‡H2O) formation. ΔH‡H2O2and ΔH‡H2O increase systematically with [NaBr], although with different sensitivities. Comparisons of activation enthalpies alongside ex situ characterization provide compelling evidence that Br atoms adsorb onto and intercalate beneath the surfaces of Pd nanoparticles and increase steady-state H2O2 selectivities, which persist without further addition of liquid-phase bromide for at least 15 h. These findings indicate H2O2 selectivities for a continuous catalytic process may be increased by a one-time (or infrequent) addition of halide promoters, which can reduce the complexity of subsequent product purification for many applications of H2O2.

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.

A Comparative Study for Application of Pitzer and ePC-SAFT Equations to Predict Volumetric and Saturation Properties in “Formation” Water

Predictions of salt solubility, brine vapor pressure and density are necessary to plan subsurface and surface operations. In this work, a comparative study was conducted to investigate prediction capabilities for salt solubility, equilibrium and volumetric properties of several minerals in “Formation” water by the Pitzer model (a commonly used industrial model) and by the ePC-SAFT equation of state (EOS). To achieve this, several validation and comparison steps were considered for reliable implementation of both models. Firstly, solubility, brine densities and vapor pressures for single-salt solutions were predicted. Afterward, the models’ applications were extended to several mixtures of two salts to predict solubility compared to experimental data from available literature. ePC-SAFT shows promising accuracy. The average relative deviation for prediction of liquid density (which cannot be estimated with the Pitzer model) for single-salt solutions of NaBr, KCl, NaCl and Na2SO4 are 1.13%, 0.70%, 1.02% and 0.36%, respectively. The average relative deviation from experimental data of vapor pressure for mixtures of NaCl and KBr is 0.75% and for mixtures of NaBr and KCl is 0.74% for systems with different concentrations. Moreover, a stochastic regression procedure is presented to evaluate the ePC-SAFT parameters. This technique is used for strontium in different salt solutions. The average relative deviation for mean ionic activity coefficients calculated by ePC-SAFT from experimental data using the ePC-SAFT parameters of strontium from the work of Held et al. [1] for single-salt solutions of strontium chloride, strontium bromide, strontium iodide, strontium nitrate and strontium perchlorate are 19.73%, 19.96%, 15.15%, 14.95% and 25.70%, respectively. These values using the ePC-SAFT parameters of strontium regressed in this work are 6.98%, 10.13%, 8.33%, 9.59% and 10.08%, respectively. Finally, the solubility of different salts was studied for mixing of formation water (FW) and injection water (SW).

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.

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.

Thermal decomposition of bromine gordaite: NaZn4(OH)6(SO4)Br·6H2O

A new compound, NaZn4(OH)6(SO4)Br·6H2O named “Br-gordaite”, was obtained by mixing of ZnO with a solution of ZnSO4 and NaBr. The Br− ion occupies the Cl− ion tetrahedral position of the brucite-like layer of the gordaite structure without any other changes relating to the structure and chemical composition. The thermal decomposition of the new phase was studied by DSC–TG(DTG)–MS in regard to the thermal events and mass loss during volatile releasing, while phase composition and chemical composition of the initial and heating products were studied by XRD and SEM–EDAX, respectively. All processes are endothermic: (1) dehydration (20–185 °C), (2) dehydroxylation (185–320 °C), (3) evolving of bromine (400–600 °C) and (4) evolving of SO3 (770–1165 °C). One-stage releasing of bromine from the “Br-gordaite” was observed at 400–600 °C. Bromine-containing intermediate crystalline phases were not detected by XRD during the “Br-gordaite” decomposition. The presence of bromine in the solid residue at 340 °C was established by chemical analysis, while after 600 °C the bromine was no longer present. The final products of the thermal decomposition of “Br-gordaite” are ZnO and traces of Na2Zn(SO4)2. The thermal behavior and the obtained thermal decomposition products of the “Br-gordaite” were compared with other minerals with Zn octahedral–tetrahedral hydroxide layer.

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.