Sodium Halide Salts Research Articles

Induction heating-based pulsed spray drier for dewatering of alkali metal halide salts: Numerical model and its experimental validation

Dewatering of alkali metal halide salts in conventional co-current or counter-current spray driers to obtain low moisture content and agglomeration in resultant dried powders is difficult owing to their hygroscopic nature. Co-current spray driers offer the advantage of good heat transport characteristics in spray zone while counter-current spray driers offer better thermal utilization throughout the drying chamber. In the present work, modified prototype of a conventional counter-current spray drier is developed to obtain both these advantages in the drying chamber by employing induction heating and mechanical pulsation techniques. After carrying out several experiments in this prototype viz. Induction heating-based pulsed spray drier (IH-PSD), the optimal process parameters are obtained which maximize thermal utilization throughout the drying chamber and minimize both moisture content and agglomeration in resultant dried powders of sodium and potassium halide salts. The initial droplet and final particle size distributions are obtained using laser diffraction analyzer and sieve shaker experiments respectively. An experimentally validated numerical model implemented using open-source computational solvers is utilized to obtain average drying rates in IH-PSD. It is observed that the average drying rate lies between 0.03 and 0.18 mg/s and 0.04 and 0.14 mg/s for sodium and potassium metal halide salts respectively.

Selective sodium halide over potassium halide binding and extraction by a heteroditopic halogen bonding [2]catenane.

The synthesis and ion-pair binding properties of a heteroditopic [2]catenane receptor exhibiting highly potent and selective recognition of sodium halide salts are described. The receptor design consists of a bidentate halogen bonding donor motif for anion binding, as well as a di(ethylene glycol)-derived cation binding pocket which dramatically enhances metal cation affinity over previously reported homo[2]catenane analogues. 1H NMR cation, anion and ion-pair binding studies reveal significant positive cooperativity between the cation and anion binding events in which cation pre-complexation to the catenane subsequently 'switches-on' anion binding. Notably, the heteroditopic catenane displayed impressive selectivity for sodium halide recognition over the corresponding potassium halides. We further demonstrate that the catenane is capable of extracting solid alkali metal salts into organic media. Crucially, the observed solution phase binding selectivity for sodium halides translates to superior functional extraction capabilities of these salts relative to potassium halides, overcoming the comparatively higher lattice enthalpies NaX > KX dictated by the smaller alkali metal sodium cation. This is further exemplified in competitive solid-liquid experiments which revealed the exclusive extraction of sodium halide salts from solid mixtures of sodium and potassium halide salts.

Lithium chloride selective ion-pair recognition by heteroditopic [2]rotaxanes.

The first heteroditopic [2]rotaxane host systems capable of strong and selective binding of lithium chloride ion-pair species are described. Importantly, a cooperative 'switch on' mechanism was found to operate, in which complexation of a lithium metal cation enhances the halide anion affinity of the rotaxanes via a combination of favourable proximal electrostatic and preorganised allosteric effects. The mechanically bonded rotaxane host design features a macrocycle component possessing a 2,6-dialkoxy pyridyl cation binding motif and an isophthalamide anion binding group, as well as an axle component functionalised with either a halogen bonding (XB) iodotriazole or hydrogen bonding (HB) prototriazole moiety. Extensive quantitative 1H NMR titration studies in CD3CN/CDCl3 solvent mixtures determined enhanced ion-pair binding affinities for lithium halides over the corresponding sodium or potassium halide salts, with the axle prototriazole-containing HB rotaxane in particular demonstrating a marked selectivity for lithium chloride. Solid-state X-ray crystallographic studies and computational DFT investigations provide evidence for a [2]rotaxane host axle-separated ion-pair binding mode, in which complementary cation and anion binding motifs from both the macrocycle and axle components act convergently to recognise each of the charged guest species.

Molten Sodium Batteries – Lewis Acidity of AlCl3/NaI Catholyte Impedes NaSICON Interface

Low temperature molten sodium batteries with sodium metal anodes, NaSICON solid-state separators, and sodium halide salt catholytes are low cost, earth-abundant technologies for grid-scale energy storage.1-3 We compared batteries with NaI/AlCl3-based molten salt catholytes of differing Lewis acidities at 110 °C. Batteries with >50 mol% AlCl3 (acidic catholytes) experienced a linear decline in energy efficiency during cycling, whereas batteries with >50 mol% NaI (basic catholytes) maintained 95% energy efficiency for 100 cycles (5 months) at 2.5 mA cm-2. A 3-electrode cell was developed, enabling electrochemical identification of the NaSICON-catholyte interface as the source of increased impedance. Complementary physical and chemical characterization of the NaSICON exposed to acidic and basic catholytes showed no changes in crystallinity, bulk morphology, or bulk chemical composition, but surface sensitive X-ray photoelectron spectroscopy (XPS) revealed subtle changes in the local NaSICON surface chemistry. In addition, Raman spectroscopy indicated that basic catholytes lack the dimer species Al2Cl6I- present in acidic catholytes. These results suggest that one means to enable efficient and stable battery cycling is maintaining Lewis-basic NaI/AlCl3, which avoids deleterious interactions at the NaSICON-catholyte interface. Recent progress towards achieving high cycling rates in these molten salt systems will also be shared.References L. J. Small, A. Eccleston, J. Lamb, A. C. Read, M. Robins, T. Meaders, D. Ingersoll, P. G. Clem, S. Bhavaraju and E. D. Spoerke, J. Power Sources, 360, 569 (2017).S. J. Percival, L. J. Small and E. D. Spoerke, J. Electrochem. Soc., 165, A3531 (2018).M. M. Gross, S. J. Percival, L. J. Small, J. Lamb, A. S. Peretti and E. D. Spoerke, ACS Appl. Energy Mater., 3, 11456 (2020). Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Squaramide-Based Heteroditopic [2]Rotaxanes for Sodium Halide Ion-Pair Recognition.

A series of squaramide-based heteroditopic [2]rotaxanes consisting of isophthalamide macrocycle and squaramide axle components are synthesized using an alkali metal cation template-directed stoppering methodology. This work highlights the unprecedented sodium cation template coordination of the Lewis basic squaramide carbonyls for interlocked structure synthesis. Extensive quantitative 1 H NMR spectroscopic anion and ion-pair recognition studies reveal the [2]rotaxane hosts are capable of cooperative sodium halide ion-pair mechanical bond axle-macrocycle component recognition, eliciting up to 20-fold enhancements in binding strengths for bromide and iodide, wherein the Lewis basic carbonyls and Lewis acidic NH hydrogen bond donors of the squaramide axle motif operate as cation and anion receptive sites simultaneously in an ambidentate fashion. Notably, varying the length and nature of the polyether cation binding unit of the macrocycle component dramatically influences the ion-pair binding affinities of the [2]rotaxanes, even overcoming direct contact NaCl ion-pair binding modes in polar organic solvents. Furthermore, the cooperative ion-pair binding properties of the squaramide-based heteroditopic [2]rotaxanes are exploited to successfully extract solid sodium halide salts into organic media.

Elucidating the role of anionic chemistry towards high-rate intermediate-temperature Na-metal halide batteries

Sodium (Na)-based battery technologies that are economical (because Na is abundant) and have long cycle life are gaining importance for large-scale energy storage applications. Among the widely studied Na-based battery systems, intermediate-temperature (IT) Na-metal halide (Na-MH) batteries have demonstrated several advantages over conventional high-temperature Na batteries, including superior battery safety, lower operating temperature and manufacturing cost, potentially longer cycle life, and easier assembly. However, the rate performance of IT Na-MH batteries is inevitably affected by the lower operating temperature. In pursuit of faster charge-transfer reaction kinetics, we extended our studies of cathode materials beyond the extensively investigated NiCl2 to NiBr2 (NaBr/Ni) and NiI2 (NaI/Ni) compounds. We systematically investigated the synergetic effects of anion chemistry on the electrochemical properties. Surprisingly, among three tested cathodes, the NaBr/Ni cathode showed the highest energy density of 174 Wh/kg at 33.3 mA/cm2 (~0.8C), which is 2.5 and 1.9 times higher than those of NaCl/Ni and NaI/Ni cells. We explored the underlying enhancement mechanism in great detail via multiple structural characterization and electrochemical techniques. The sodium-halide salt dissolution in molten NaAlCl4 was found to be the determining factor in rate improvement. Our findings will greatly advance IT Na-MH battery technologies and pave the way towards fundamental understanding of reaction kinetics for high-temperature batteries in general.

The effect of sodium halide salts on the kinetics of tetrahydrofuran hydrate formation by using a differential scanning calorimetry method

In this study, the effect of sodium halide salts including Sodium Fluoride, Sodium Iodide, Sodium Bromide, and Sodium Chloride was investigated on the kinetics of tetrahydrofuran hydrate formation by using a differential scanning calorimetry setup. It was found that the anions of salts can destroy hydrogen bonding between the water molecules and prevent the growth of gas hydrate. The fluorine with the smallest ionic radius and the highest enthalpy of hydration was the most effective material to decrease the hydrate growth rate. According to the results, the formation kinetics of hydrate changes with the concentration of salts in a different manner. Results show that the hydrate formation rate decreases with increasing the concentration of salts up to 0.6 wt%, while it increases when the concentration is at a range of 0.6 to 1.2 wt%. The rate begins to decrease by the concentration of >1.2 wt%. It was found that the parameters such as the hydration effect and the activity coefficients of salt solutions can affect the kinetics of tetrahydrofuran hydrate formation.

Physical properties of deep eutectic solvents formed by the sodium halide salts and ethylene glycol, and their mixtures with water

Deep eutectic solvents (DESs), with their attractive properties, are currently of great interest. Introducing new kinds of eutectic solvents with different components as their hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA), and investigating the (thermo-) physical properties of the new DESs can play an important role in promoting future research and use of such mixtures. In this study, we investigate the feasibility of the formation of new kinds of eutectic solvents based on the sodium halide salts as the hydrogen bond acceptors with ethylene glycol as the hydrogen bond donor. Different molar fractions of HBD/HBA were investigated. The results indicated that sodium fluoride does not form a DES throughout the whole concentration range investigated, while sodium chloride, sodium bromide, and sodium iodide do form eutectic mixtures at certain molar ratios. Differential scanning analysis was performed on the resulting eutectic solvents to measure the glass transition temperature. Other physical properties of the proposed DESs, namely density, viscosity, refractive index, and electric conductivity were also measured within the temperature range of 293–333 K. Furthermore, the effect of water in aqueous mixtures of the proposed DESs was investigated, with molar fractions of water ranging from 0.1 to 0.9. Based on the calculations of excess molar volume, the effect of water in the mixtures was investigated. Over the whole range of water concentrations in the mixture, the excess molar volumes had negative values, indicating intensive hydrogen-bonding between unlike molecules in the mixture and/or a void filling mechanism by the smaller molecules.

Effect of Halide Anions on the Structure and Dynamics of Water Next to an Alumina (0001) Surface

While ions are known to perturb hydrogen bonding networks in bulk water, our understanding of such effects is less developed for interfaces. Alumina/water interfaces are highly ordered due to strong hydrogen bonding interactions between interfacial water molecules and adjacent aluminol groups. However, how ions alter this interaction is not yet known. Herein, to address the effect of sodium halide salts on the hydrogen bonding environment of interfacial water, we investigated charged alumina (0001) surfaces using steady-state and time-resolved vibrational sum frequency generation (vSFG) spectroscopy. Our results indicate that the effect of halide anions on the attenuation of the vSFG signal next to positively and negatively charged alumina surfaces followed the sequence F– ≫ Br– > Cl– > I– (slightly varied direct Hofmeister series) and Br– > I– ≈ Cl– > F– (slightly varied indirect Hofmeister series), respectively. Additionally, time-resolved vSFG reveals that only F– perturbs the vibrational lifetime of w...

A mild halogenation of pyrazoles using sodium halide salts and Oxone

A mild, inexpensive, and operationally simple pyrazole halogenation method utilizing Oxone and sodium halide salts is reported. This work documents 17 examples of alkyl, aryl, allyl, and benzyl substituted 4-chloro and 4-bromopyrazoles, obtained in up to 93% yield. Reactions are performed in water under ambient conditions and generation of organic byproducts is avoided.

The time-dependent stimulation of sodium halide salts on redox reactants, energy supply and luminescence in Vibrio fischeri

The excess of halide ions (F−, Cl−, Br−, I−) can cause adverse effects. Earlier studies demonstrated time-dependent stimulations of organic salts with halide ions on photobacteria. Therefore, inorganic ones with halide ions (e.g., NaX, X=F−, Cl−, Br−, I−) were assumed to cause similar effects. In the present study, Vibrio fischeri was exposed to NaX. Results showed that the contents of favin mono-nucleotide (FMN), nicotinamide adenine dinucleotide (NADH), and nicotinamide adenine dinucleotide phosphate (NADPH) were stimulated by NaX with a time-dependent fashion. The maximum stimulations on FMN at 24h were 172%, 168%, 211% and 298% of the control (p<0.05) in NaF, NaCl, NaBr and NaI, respectively, with an order of NaF≈NaCl<NaBr<NaI. The maximum stimulations on NAD(P)H at 24h followed similar orders. Similar time-dependent stimulatory effects were observed in the FMN:NAD(P)H reaction catalyst (luciferase, in the form of expression levels of lux A and lux B), adenosine triphosphate and the expression levels of its regulating gene adk. The luminescent stimulations were significantly higher than the biochemical ones despite of similar time-dependence and stimulation order among NaX. The overall results showed a common hormetic pattern in sodium halide salts.

Halide Welding for Silver Nanowire Network Electrode.

We developed a method of chemically welding silver nanowires (AgNWs) using an aqueous solution containing sodium halide salts (NaF, NaCl, NaBr, or NaI). The halide welding was performed simply by immersing the as-coated AgNW film into the sodium halide solution, and the resulting material was compared with those obtained using two typical thermal and plasmonic welding techniques. The halide welding dramatically reduced the sheet resistance of the AgNW electrode because of the strong fusion among nanowires at each junction while preserving the optical transmittance. The dramatic decrease in the sheet resistance was attributed to the autocatalytic addition of dissolved silver ions to the nanowire junction. Unlike thermal and plasmonic welding methods, the halide welding could be applied to AgNW films with a variety of deposition densities because the halide ions uniformly contacted the surface or junction regions. The optimized AgNW electrodes exhibited a sheet resistance of 9.3 Ω/sq at an optical transmittance of 92%. The halide welding significantly enhanced the mechanical flexibility of the electrode compared with the as-coated AgNWs. The halide-welded AgNWs were successfully used as source-drain electrodes in a transparent and flexible organic field-effect transistor (OFET). This simple, low-cost, and low-power consumption halide welding technique provides an innovative approach to preparing transparent electrodes for use in next-generation flexible optoelectronic devices.

Electrochemical Characterization of Low Temperature Molten Salt Electrolyte for Sodium Based Liquid Metal Batteries

The electrochemical behavior of a ternary eutectic mixture of sodium amide (NaNH2), sodium hydroxide (NaOH) and sodium iodide (NaI) was investigated to elucidate its validity as an electrolyte for sodium-based liquid metal batteries. The liquid metal battery consists of two metals with different electronegativity separated by molten salt. The self-segregating nature of the three layers allows for easy assembly and scalability. Moreover, the all-liquid design allows the batteries to operate at high current densities with negligible losses because of the high conductivity of molten salts and fast transport properties in the liquid state. Sodium-based liquid metal batteries are particularly attractive due to the low cost of sodium metal (Na) and its low melting temperature (98°C). However, due to the high melting temperature of sodium halide salt (Tm > 500°C), the early efforts to build a sodium-based liquid metal battery faced the obstacle of high self-discharge and short life cycle.1 In our previous work, using a eutectic NaOH-NaI salt (Tm: 223°C), we demonstrated a Na||Bi-Pb cell operated at lower temperature ~250°C with small self-discharge. In order to further decrease operating temperature to less than 200 °C, in this work, we investigated a ternary eutectic 52%NaNH2,38%NaOH and 10%NaI (Tm: 127°C) 2. By using a three-electrode setup consisting of a liquid Na in β"-Al2O3 as a reference electrode, and tungsten wires as counter and working electrodes, cyclic voltammetry was performed at different scan rates (50, 100, and 200 mVs-1) and at 180 °C operating temperature. The electrochemical window of the ternary electrolyte was identified as 1.3 V with the sodium deposition as the cathodic limit and the oxidation of NH2 - anions to form N2H4gas as the anodic limit. Bismuth-lead (Bi-Pb) alloy is a candidate for positive electrode due to its low eutectic point (125 °C). Known thermodynamic properties of Na-Bi-Pb3 and previous work4 indicate that the operating voltage of the Na||Bi-Pb cell is expected to be within the electrochemical window of NaNH2-NaOH-NaI electrolyte. In this work, we focused on the discharge behavior of positive electrode, corresponding to the alloying process of Na in Bi-Pb alloy, in the ternary electrolyte. Using a similar three electrode setup utilizing liquid Na in β"-Al2O3 reference electrode, eutectic Bi-Pb working electrodes and a Na-Bi-Pb counter electrode, we obtained the voltage-time trace during alloying process and prepared the samples at varying Na concentration and current densities at 180°C operating temperature. The samples were quenched at target concentration of Na and cross-sectioned samples were analyzed using energy dispersive x-ray spectroscopy and scanning electron microscopy. We found that the Na preferentially alloys with Bi due to its stronger interaction than that with Pb (Pb works as diluent) and forms intermetallic, such as Na3Bi, similar to Li-Sb-Pb system 5 and Ca-Sb-Pb system.6 A smooth voltage profile on discharging to 10 at% of Na in the Bi-Pb electrode at 100 mAcm-2suggests potential feasibility of the ternary electrolyte for the sodium-based liquid metal batteries.

Comparison of Aggressiveness Behavior of Chloride and Iodide Solutions on 304 and 304L Stainless Steel Alloys

The aggressive effect of chloride anion in comparison to iodide anion on the pitting corrosion attack of 304 and 304L stainless steel (SS) alloys was investigated by using the cyclic potentiodynamic polarization test at 0.6 M Sodium Halide salts (NaX) solution and different temperatures. The two alloys 304 and 304L SS suffered from severe pitting corrosion at room temperature up to 50°C in a chloride containing solution with the higher resistance observed for 304L in comparison to the 304 while on pits were detected in iodide solution for both alloys. The pitting potentials of the two alloys in 0.6 M NaCl solution reduced with the increase of the temperature. Examination of the alloys’ surfaces was conducted by using the scanning electron microscopes where it revealed that the occurrence of pitting attack seems like hemispherical or irregular pits with different sizes.

A Microfluidic Method for Investigating Ion-Specific Bubble Coalescence in Salt Solutions.

This paper reports the direct and precise measurement of bubble coalescence in salt solutions using microfluidics. We directly visualized the bubble coalescence process in a microchannel using high-speed imaging and evaluated the shortest coalescence time to determine the transition concentration of sodium halide solutions. We found the transition concentration is ion-specific, and the capacity of sodium halide salts to inhibit bubble coalescence follows the order of NaF > NaCl > NaBr > NaI. The microfluidic method overcomes the inherent uncertainties in conventional large-scale devices and methods.

Multifold Increases in Turing Pattern Wavelength in the Chlorine Dioxide-Iodine-Malonic Acid Reaction-Diffusion System.

Turing patterns in the chlorine dioxide-iodine-malonic acid reaction were modified through additions of sodium halide salt solutions. The range of wavelengths obtained is several times larger than in the previously reported literature. Pattern wavelength was observed to significantly increase with sodium bromide or sodium chloride. A transition to a uniform state was found at high halide concentrations. The observed experimental results are qualitatively well reproduced in numerical simulations with the Lengyel-Epstein model with an additional chemically realistic kinetic term to account for the added halide and an adjustment of the activator diffusion rate to allow for interhalogen formation.

Graphene Transistors Gated by Salted Proton Conductor

The first use of proton conductors for gating graphene transistors is demonstrated. The proton conductor used in this study, [poly(styrenesulfonic acid)], is added with sodium halide salts in order to improve the capacitive characteristics of the electrolyte gate dielectric. The influence of the added sodium halide salts (NaF, NaCl, NaBr, and NaI), the salt concentration, and the relative humidity on the dielectric properties of the electrolyte are investigated systematically. Substantial enhancement in the device performances of the graphene transistors including carrier mobility, device ON current, Dirac voltage, and device cut‐off frequency is attained with the addition of the sodium halide salts. From the optimized conditions based on NaI salts, the graphene transistors exhibit hole and electron mobilities of 1900 and 990 cm2 V–1 s–1, respectively, with Dirac voltage near 0 V. Moreover, the cut‐off frequency of the device presenting the dynamic characteristics of a transistor reach up to 100 kHz.

Study of sodium halide aqueous solutions treatment for ethane hydrate formation kinetics

The aim of this work is to present the experimental investigation of ethane hydrate formation kinetics in the presence of sodium halide salt solutions containing NaF, NaCl, NaBr, and NaI. To achieve this aim, the variations of pressure versus time have been measured during hydrate formation process. The temperature, volume of reactor and stirring velocity are 277K, 500ml, and 840rpm, respectively. The influence of anion type salts and their concentrations on induction time and hydrate formation rate have been studied. The result prove that sodium halides (NaF, NaCl, and NaI) at a concentration of about 0.6wt% and sodium bromide (NaBr) at concentration ranged 0.3–1.5wt% have minimum promotion effect on the ethane hydrate formation rate. Also, the results of present study show a significant decrease in hydrate formation rate at a concentration higher than 1.5wt% for sodium halides.

Aqueous Copper(II) Photoinduced Polymerization of Acrylates: Low Copper Concentration and the Importance of Sodium Halide Salts.

Photoinduced metal-mediated radical polymerization is a rapidly developing technique which allows for the synthesis of macromolecules with defined molecular weight and narrow molecular weight distributions, although typically exhibiting significant limitations in aqueous media. Herein we demonstrate that the presence of alkali metal halide salts, in conjunction with low copper concentration and UV irradiation, allows for the controlled polymerization of water-soluble acrylates in aqueous media, yielding narrow molecular weight distributions and high conversions. Despite the aqueous environment which typically compromises polymer end group fidelity, chain extensions have also been successfully performed and different degrees of polymerization were targeted. Importantly, no conversion was observed in the absence of UV light and the polymerization could be switched "on" and "off" upon demand, as demonstrated by intermittent light and dark periods and thus allowing access to spatiotemporal control.

Adsorption Behavior of Low-Concentration Imidazolium-Based Ionic Liquid Surfactant on Silica Nanoparticles.

The adsorption behavior of imidazolium-based ionic liquid surfactant ([C12mim]Br) on silica nanoparticles (NPs) has been studied with turbidity, isothermal titration microcalorimetry, fluorescence spectroscopy, and dynamic light scattering (DLS) measurements. Both the electrostatic attraction and the hydrogen bonding interaction between silica NP and [C12mim]Br play crucial roles during [C12mim]Br monomers binding to silica NPs at low surfactant concentration, and the hydrophobic effect leads to formation of micelle-like aggregates on silica NP surfaces with the further increase of surfactant concentration. Furthermore, it is found that sodium halide salts favor the adsorption of [C12mim]Br on silica NP surfaces by decreasing the electrostatic repulsions. Anions with more hydrophobicity and the ability to form hydrogen bonding have more pronounced effect. Compared with DTAB, [C12mim]Br has much stronger binding ability with silica NPs at pH 7.0. More interestingly, [C12mim]Br can still form micelle-like aggregates on silica NP surfaces, but DTAB cannot at pH 2.0. The hydrogen bonding between the imidazolium ring and silica NPs is the principal contributor to these observations. Our results will contribute to the elucidation of silica NP/cationic surfactant interaction from molecular scale and the widely applications of silica NP/surfactant systems in practice.