Alkali Metal Chloride Salts Research Articles

Particle morphology of alkali metal chloride salts in induction heating based pulsed spray drier: Experimental analysis and ANN prediction

Hygroscopic nature of alkali metal chloride salts makes attaining mono-sized dried particles from their aqueous precursor solution an engineering challenge for conventional co-current or counter-current spray driers. Conventional spray driers offer better thermal utilization in either the spray zone or dried particle zone depending on their configuration viz. co-current or counter-current, respectively. In this work, an alternative prototype named induction heating based pulsed spray drier (IH-PSD) is proposed to obtain dry alkali metal chloride salt powders with narrow particle size distribution. Laser diffraction analysis is carried out for initial droplet size distribution whereas scanning electron microscopy and sieve shaker analysis is carried out for studying the particle morphology and particle size distribution of dried powder for all the selected salts. The resultant particle properties emphasized in the present work are the dried particle to initial droplet diameter ratio and the wet basis moisture content. It has been observed that the ratio of mean volume diameter of dried particle to sauter mean diameter of initial droplet lies in the range of 0.4–3.6 meanwhile the wet basis moisture content of dried powder lies in the range of 1.4–3.6 for the selected salts. Artificial neural network (ANN) model is applied for inferring the influence of IHPSD process parameters on the above mentioned dried particle properties and satisfactory convergence with experimental values has been achieved.

Design and development of induction heating based pulsed spray dryer for alkali metal chloride salts: interrogation through CFD approach

Design and development of induction heating based pulsed spray dryer for alkali metal chloride salts: interrogation through CFD approach

Experimental exploration of metallic chloride salt corrosion of stainless steel sheets

In recent years, biomass generation in China has been steadily increasing. The high-temperature corrosion of the heating surface of biomass boilers is mainly caused by HCl and alkali metal chlorides in the sediment, which seriously affects the efficiency and safety and the degree of economic utilization of biomass energy. In this paper, the corrosion products were characterized by total-immersion experiments under constant temperature on different thicknesses of 304 stainless steel in various concentrations and types of alkali metal chloride salts. Through thermal microscopy scanning and XRD experiments, the composition, characteristics, and microscopic morphology of corrosion products on stainless steel flakes are determined to find out the corrosion mechanism of stainless steel flakes in solution alkali metal chloride salts. The results show that in a water bath at 80 °C, alkali metal chlorides weaken the corrosion resistance of the stainless-steel sheet by destroying the integrity of its reticular structure, thus promoting the chemical reaction between the iron contained in the stainless steel and other elements to generate various types of corrosion products rich in iron. Meanwhile, among various alkali metal chloride salts, the catalytic effect of saturated CaCl2 on the corrosion of 0.1 mm and 0.01 mm stainless steel sheets at 80 °C is the most significant.

Cation and buffer specific effects on the DNA-lipid interaction

Knowledge of DNA - lipid layer interactions is key for the development of biosensors, synthetic nanopores, scaffolds, and gene-delivery systems. These interactions are strongly affected by the ionic composition of the solvent. We have combined quartz crystal microbalance (QCM) and ellipsometry measurements to reveal how pH, buffers and alkali metal chloride salts affect the interaction of DNA with lipid bilayers (DOTAP/DOPC 30:70 in moles). We found that the thickness of the DNA layer adsorbed onto the lipid bilayer decreased in the order citrate > phosphate > Tris > HEPES. The effect of cations on the thickness of the DNA layer decreased in the order (K+ > Na+ > Cs+ ∼ Li+). Rationalization of the experimental results requires that adsorption, due to cation specific charge screening, is driven by the simultaneous action of two mechanisms namely, the law of matching water affinities for kosmotropes (Li+) and ion dispersion forces for chaotropes (Cs+). The outcome of these two opposing mechanisms is a “bell-shaped” specific cations sequence. Moreover, a superimposed buffer specificity, which goes beyond the simple effect of pH regulation, further modulated cation specificity. In summary, DNA-lipid bilayer interactions are maximized if citrate buffer (50 mM, pH 7.4) and KCl (100 mM) are used.

Molten Salt Templated Synthesis of Covalent Isocyanurate Frameworks with Tunable Morphology and High CO2 Uptake Capacity.

The use of reactive molten salts, i.e., ZnCl2, as a soft template and a catalyst has been actively investigated in the preparation of covalent triazine frameworks (CTFs). Although the soft templating effect of the salt melt is more prominent at low temperatures, close to the melting point of ZnCl2, leading to the formation of abundant micropores, a significant mesopore formation is observed that is due to the partial carbonization and other side reactions at higher temperatures (>400 °C). Evidently, high-temperature synthesis of CTFs in various eutectic salt mixtures of ZnCl2 with alkali metal chloride salts also leads to mesopore formation. We reasoned that using the isocyanate moieties instead of cyano groups in the monomer, 1,4-phenylene isocyanate, could enable efficient interactions between carbonyl moieties and alkali metal ions to realize efficient salt templating to form covalent isocyanurate frameworks (CICFs). In this direction, the trimerization of 1,4-phenylene diisocyanate was carried out under ionothermal conditions at different reaction temperatures using ZnCl2 (CICF) and the eutectic salt mixture of KCl/NaCl/ZnCl2 (CICF-KCl/NaCl) as the reactive solvents. We observed notable differences in the morphologies of the two polymers, whereas CICF showed irregular-shaped micrometer-sized particles, the CICF-KCl/NaCl exhibited a filmlike morphology. Moreover, favorable ion-dipole interactions between alkali metal cations and oxygen atoms of the monomer facilitated two-dimensional growth and the formation of a purely microporous framework in the case of CICF-KCl/NaCl along with a near theoretical retention of the nitrogen content at 500 °C. The CICF-KCl/NaCl showed a BET surface area of 590 m2 g-1 along with a CO2 uptake capacity of 5.9 mmol g-1 at 273 K and 1.1 bar because of its high microporosity and nitrogen content. On the contrary, in the absence of alkali metal ions, CICF showed high mesopore content and a moderate CO2 uptake capacity. This study underscores the importance of the strength of the interactions between the salts and the monomer in the ionothermal synthesis to control the morphology, porosity, and gas uptake properties of the porous organic polymers.

Study on Tensile Creep Behavior of 12Cr1MoV Alloy Steel under High-Temperature Alkali Metal Salt Environment for Solar Thermal Power Generation

The heat exchange tubes of solar thermal power generation work in molten salt environment with periodic temperature change. In order to reveal the tensile creep behavior of 12Cr1MoV pipeline steel under high-temperature alkali metal salt environment, the tensile creep behavior of 12Cr1MoV alloy under different applied load and reaction temperature in high-temperature alkali metal chloride salt environment was studied. The results show that the deformation of 12Cr1MoV alloy in 600°C, NaCl-35%KCl mixed salt environment is mainly controlled by diffusion creep; with the increase of stress, the creep life of 12Cr1MoV alloy decreases. The creep fracture mechanism of 12Cr1MoV alloy in 600°C, NaCl-35%KCl mixed salt environment is intergranular ductile fracture; the increase of temperature will enhance the activation and oxidation of the chlorine atoms, thereby accelerating the corrosion of the base metal and increasing the spheroidization speed of the pearlite matrix, and the creep deformation rate of the alloy increases with increasing temperature.

Study on the Corrosion Fatigue Properties of 12Cr1MoV Steel at High Temperature in Different Salt Environments

Biomass energy, as a reliable renewable energy source, has gained more and more attention. However, microstructure degradation and corrosion fatigue damage of heat pipes hinder its further application. In this paper, high temperature corrosion fatigue characteristics of 12Cr1MoV steel under a mixed alkali metal chloride salt environment and mixed sulfate salt environment were investigated. Fatigue tests with different total strain amplitudes were performed. Results show that the effect of total strain amplitude on the cyclic stress response of the alloy is approximately the same under three different deformation conditions. With the increase of the cyclic numbers, the alloyed steel mainly exhibited cyclic hardening during loading. The fatigue properties in air environment were the best, which is most obvious when the total strain amplitude is ±0.3%. The fatigue life of samples in mixed alkali metal salts is the shortest. Furthermore, the fatigue fracture morphology of the alloyed steel in different environments were also deeply analyzed. This experimental study attempts to provide a theoretical reference for solving the problem of rapid failure of heat pipes in biomass boilers, and to establish a scientific basis for the material selection and safety operation.

Influence of salt on nanozeolite-Y particles size synthesized under organic template-free condition

Abstract Zeolite-Y is one of the preferred micro-sized zeolite commonly used as a catalyst and for adsorption and separation. The size and shape of zeolite crystals have great influence on their properties therefore the synthesis of nano-size zeolite-Y has received much attention with straightforward methodology. In the present study, nano-sized zeolite-Y crystals were synthesized by the clear-solution (CS) and dense-gel (DG) methods in the presence of alkali metal chloride salt (i.e. NaCl) under organic template-free condition. The influence of the salt on the growth of nano zeolite-Y crystal size and morphology was studied systematically by varying the NaCl concentration. Depending on the method selected for synthesis (CS or DG), the growth of nano-size crystals was affected by the addition of NaCl content. In the CS method, the size of zeolite-Y crystals was found to decrease from 120 nm to 60 nm with an increase of salt content which signify the influence of salt in hindering diffusion of nutrients to the crystal nuclei in a homogeneous starting gel. Whereas, the spherical aggregates of well-shaped nanocrystals were formed with an increase of crystal size in the case of DG method. This is attributed to the suppression of the rate of crystal dissolution in dense-gel system upon introduction of salt ions. The nano-size zeolite-Y synthesized by both methods exhibited comparatively higher water adsorption capacity (15.4 ± 0.38–16.2 ± 0.41 mmol/g) than commercially available micro-size zeolite-Y (12.9 mmol/g) which can be attributed to the contribution of the meso/macropores arising from the inter-crystal voids. Hence, the synthesized nano-size zeolite-Y can be considered as promising adsorbents for water adsorption applications.

Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature.

Water is a ubiquitous solvent in biological, physical, and chemical processes. Unique properties of water result from water’s tetrahedral hydrogen-bonded (HB) network (THBN). The original THBN is destroyed when water is confined in a nanosized environment or localized at interfaces, resulting in corresponding changes in HB-dependent properties. In this work, we present an innovative idea to validate the reserve energy of high-energy water and applications of high-energy water to promote water’s fundamental activities of solubility, ionic conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs). Compared to conventional deionized (DI) water, solubilities of alkali metal-chloride salts in high-energy water were significantly increased, especially for salts that release heat when dissolved. The ionic conductivity of NaCl in high-energy water was also markedly higher, especially when the electrolyte’s concentration was extremely low. In addition, antioxidative components, such as polyphenols and 2,3,5,4’-tetrahydroxystilbene-2-O-beta-d-glucoside (THSG) from teas, and Polygonum multiflorum (PM), could more effectively be extracted using high-energy water. These results demonstrate that high-energy water has emerged as a promising innovative solvent for promoting water’s fundamental activities via effective energy transfer.

Comprehensive Cysteine-scanning Mutagenesis Reveals Claudin-2 Pore-lining Residues with Different Intrapore Locations

The first extracellular loop (ECL1) of claudins forms paracellular pores in the tight junction that determine ion permselectivity. We aimed to map the pore-lining residues of claudin-2 by comprehensive cysteine-scanning mutagenesis of ECL1. We screened 45 cysteine mutations within the ECL1 by expression in polyclonal Madin-Darby canine kidney II Tet-Off cells and found nine mutants that displayed a significant decrease of conductance after treatment with the thiol-reactive reagent 2-(trimethylammonium)ethyl methanethiosulfonate, indicating the location of candidate pore-lining residues. Next, we stably expressed these candidates in monoclonal Madin-Darby canine kidney I Tet-Off cells and exposed them to thiol-reactive reagents. The maximum degree of inhibition of conductance, size selectivity of degree of inhibition, and size dependence of the kinetics of reaction were used to deduce the location of residues within the pore. Our data support the following sequence of pore-lining residues located from the narrowest to the widest part of the pore: Ser(68), Ser(47), Thr(62)/Ile(66), Thr(56), Thr(32)/Gly(45), and Met(52). The paracellular pore appears to primarily be lined by polar side chains, as expected for a predominantly aqueous environment. Furthermore, our results strongly suggest the existence of a continuous sequence of residues in the ECL1 centered around Asp(65)-Ser(68) that form a major part of the lining of the pore.

Enhancement of specific heat capacity of high-temperature silica-nanofluids synthesized in alkali chloride salt eutectics for solar thermal-energy storage applications

In this study, we report the anomalous enhancement of specific heat capacity of high-temperature nanofluids. Alkali metal chloride salt eutectics were doped with silica nanoparticles at 1% mass concentration. The specific heat capacity of the nanofluid was enhanced by 14.5%. Dispersion behavior of the nanoparticles in the eutectic was confirmed by scanning electron microscopy (SEM). Three independent competing transport mechanisms are enumerated to explain this anomalous behavior.

ChemInform Abstract: Salt-Templated Open Frameworks (CU-2): Novel Phosphates and Arsenates Containing M3(X2O7)22- (M: Mn, Cu; X: P, As) Micropores 5.3 Å and 12.7 Å in Diameter.

We have recently isolated a novel family of salt-templated phosphates and arsenates, A2M3(X2O7)2·(salt) [where A = K, Rb, Cs; M = Mn, Cu; X = P, As]. The space-filling, charge-compensation alkali metal chloride salts can be removed conveniently without destroying the MXO framework. These materials (designated as CU-2-MXO) exhibit microporous structures (ca. 5.3 and 12.7 A in diameter) in which the active transition metal sites are distributed in a spatially uniform manner throughout the bulk. The salt lattice functions as a structure-directing template. The single-crystal structure shows that the large pore contains a remarkable ACl/CsCl lattice that consists of two interpenetrating, square antiprismatic columns of ions. In contrast to organically templated microporous solids, these new materials were synthesized by conventional solid-state reactions at high temperatures. Consequently, the resulting compounds can endure extensive heating to ca. 650 °C. These materials, in fact, possess the highest thermal...

Improved Micellar Hydration and Gelation Characteristics of PEO−PPO−PEO Triblock Copolymer Solutions in the Presence of LiCl

LiCl-induced changes in the micellar hydration and gelation characteristics of aqueous solutions of the two triblock copolymers F127 (EO(100)PO(70)EO(100)) and P123 (EO(20)PO(70)EO(20)) (where EO represents the ethylene oxide block and PO represents the propylene oxide block) have been studied by small-angle neutron scattering (SANS) and viscometry. The effect of LiCl was found to be significantly different from those observed for other alkali metal chloride salts such as NaCl and KCl. This can be explained on the basis of the complexation of hydrated Li(+) ions with the PEO chains in the micellar corona region. The interaction between the chains and the ions is more significant in the case F127 because of its larger PEO block size, and therefore, micelles of this copolymer show an enhanced degree of hydration in the presence of LiCl. The presence of the hydrated Li(+) ions in the micellar corona increases the amount of mechanically trapped water there and compensates more than the water molecules lost through the dehydration of the PEO chains in the presence of the Cl(-) ions. The enhancement in micellar hydration leads to a decrease in the minimum concentration required for the F127 solution to form a room-temperature cubic gel phase from 18% to 14%. Moreover, for both copolymers, the temperature range of stability of the cubic gel phase also increases with increasing LiCl concentration, presumably because of the ability of the Li(+) ions to reduce micellar dehydration with increasing temperature. Viscosity studies on a poly(ethylene glycol) (PEG) homopolymer with a size equivalent to that of the PEO block in F127 (4000 g/mol) also suggest that the dehydrating effect of the Cl(-) ion on the PEG chain is compensated by its interaction with the hydrated Li(+) ions.

Some anomalous effects of sodium ions on the electrophoretic mobility and heteroaggregation of microgel particles

Experiments on the kinetics of heteroaggregation between oppositely charged particles, using both dynamic light scattering and turbidity methods, are reported. The negatively charged particles were cross-linked poly( N-isopropylacrylamide) [PNIPAM] microgel particles, prepared using a carboxylic-acid-based initiator; these particles are swollen at room temperature. The positive particles were poly(4-vinylpyridine) [P4VP] particles, prepared using an amidinium-based initiator; such particles do not respond to temperature changes but do swell below pH ∼4, where the pyridine moieties become protonated. As expected, the rate of heteroaggregation was shown to be largely independent of added salt concentration (up to ∼20 mM), for a variety of alkali metal chlorides (MCl, where M = Li, Na, K, or Rb). However, an unexpected, significant decrease in the aggregation rate was observed at certain specific sodium chloride concentrations (typically at ∼1 and also ∼4 mM). Similar effects were not seen with the other alkali metal chloride salts. This strange effect was eventually attributed to the fact that the net charge on the positively charged P4VP particles had been reduced by the adsorption of (anionic) silicate species leached from the glassware container. Sodium silicates are known to be significantly more soluble than those of the other alkali metal ions, particularly at high pH. Moreover, P4VP particles dispersed in water, ostensibly at neutral pH, do buffer the aqueous medium to pH values around 9 or higher. This mechanism was confirmed by determining the electrophoretic mobility of the P4VP particles as a function of pH in the presence of the various alkali metal chloride salts. The mobility remained positive in 1 mM salt solutions over the pH range 3 to 11 for all the salts, except for sodium chloride; in that case the mobility reversed sign at alkaline pH values. A similar effect was observed for a cationic polystyrene latex sample, prepared with the same amidinium-based initiator. These experiments demonstrate the importance of soluble silicates, leached from glass storage vessels, particularly in the presence of sodium ions. Needless to say, the “anomalous” effects disappeared when plastic storage vessels were used in place of the glass ones.

High-Temperature Synthesis of an Open-Framework Compound, Na2Cs2Cu3(P2O7)2Cl2 (CU-4), by Molten-Salt Methods

8-Ring and 16-ring channels with 5.3×5.3 Å and 4.9×17.2 Å windows, respectively, are contained in the new CU-4 phase. The larger channel exhibits an elliptical pore structure templated by an alkali metal chloride salt. CU-4 is structurally related to CU-2 (see picture), and can be chemically modified to CU-2 by an ion-exchange reaction at 600°C.

High-Temperature Synthesis of Two New Aluminophosphates, NaRb2Al2(PO4)3 and NaCs2Al(PO4)2, in Molten Alkali Metal Chloride Media

Two new aluminophosphate (AlPO) phases have been isolated via conventional solid-state reactions employing molten alkali metal chloride salts. Their structures have been determined by single-crystal X-ray diffraction methods. Crystal data: NaRb2Al2(PO4)3 1, P21/c (no. 14), a = 4.849(2) A, b = 8.216(2) A, c = 28.317(3) A, β = 90.52(2)°, and Z = 4; NaCs2Al(PO4)2 2, P21/c (no. 14), a = 10.992(2) A, b = 9.192(2) A, c = 18.998(2) A, β = 90.35(1)°, and Z = 8. 1 adopts a new structure type that contains puckered slabs of vertex-sharing AlO4, AlO5, and PO4 polyhedral units. The slab structure is made of interlinked [Al2P3O16] structural units resulting in a new 4 × 6 × 8 network of alternating Al3+ and P5+ cations. It exhibits a unique Al3P2 trigonal bipyramidal chain of fused butterfly-like Al2P3 units. 2 represents a new three-dimensional compound of the Al(PO4)23- type that consists of alternating, vertex-sharing AlO4 and PO4 units. The framework possesses a helical structure embracing around the mixed Na+ an...

Salt-Templated Open Frameworks (CU-2): Novel Phosphates and Arsenates Containing M3(X2O7)22- (M = Mn, Cu; X = P, As) Micropores 5.3 Å and 12.7 Å in Diameter

We have recently isolated a novel family of salt-templated phosphates and arsenates, A2M3(X2O7)2·(salt) [where A = K, Rb, Cs; M = Mn, Cu; X = P, As]. The space-filling, charge-compensation alkali metal chloride salts can be removed conveniently without destroying the MXO framework. These materials (designated as CU-2-MXO) exhibit microporous structures (ca. 5.3 and 12.7 A in diameter) in which the active transition metal sites are distributed in a spatially uniform manner throughout the bulk. The salt lattice functions as a structure-directing template. The single-crystal structure shows that the large pore contains a remarkable ACl/CsCl lattice that consists of two interpenetrating, square antiprismatic columns of ions. In contrast to organically templated microporous solids, these new materials were synthesized by conventional solid-state reactions at high temperatures. Consequently, the resulting compounds can endure extensive heating to ca. 650 °C. These materials, in fact, possess the highest thermal...

A new process for the separation of hafnium from zirconium

A new process for the separation of hafnium from zirconium has been developed. This process is based on the repeated reaction of the mixed tetrachloride vapors of zirconium and hafnium with alkali metal chloride salts in a solid form; hafnium tends to remain in the condensed phase while zirconium concentrates in the vapor phase. This process has been investigated experimentally as a function of the alkali chloride salt, the number of reaction steps and the mass ratio of vapor-to-condensed phases. The mechanism of the separation process is discussed in terms of thermodynamic considerations and the calculation of the theoretical separation efficiency is in agreement with the experimental results.

Matrix reactions of alkali metal chloride salts and HCl and DCl: Infrared spectra of the M+HCl2− and M+DCl2− ion pairs

The matrix reactions of alkali metal chloride salts and HCl and DCl have been investigated in argon matrices, as well as the reaction of lithium metal with HCl and DCl. From each reaction product a single intense band was observed which has been assigned to the antisymmetric stretch ν3 of the HCl2− and DCl2− anions in the M+HCl2− and M+DCl2− ion pairs. Comparisons to literature spectra, in conjunction with quartic deuterium shifts, indicate that the anion has a linear, centrosymmetric geometry in the isolated ion pair. A rough estimate for the bond strength of the hydrogen bond in this anion is 18±2 kcal/mole. Further, comparison to the spectra of earlier workers indicates that bands previously asigned to the HCl2 radical are best reassigned to the isolated HCl2− anion.

Application of irreversible thermodynamics to isotopic diffusion. Part 1.—Isotope–isotope coupling coefficients for ions and water in concentrated aqueous solutions of alkali metal chlorides at 298.16 K

From literature sources irreversible thermodynamic parameters may be obtained for all alkali metal chloride salt solutions at 298.16 K in the concentration range 0–3.0 mol dm–3. Comparable data for isotopic diffusion coefficients of component ions and water are incomplete. These have been obtained in this study, using a diaphragm cell, for all but rubidium ion in rubidium chloride. It is shown that these two sets of data may be combined to yield Onsager frictional coefficients (rii*) or mobility coefficients (lii*) which measure the kinetic interaction between isotopes as a function of concentration for each salt solution. Interpretation of lii* for ions is made difficult because of large frame-of-reference contributions with water solvent, but these may be compared with values calculated from the Onsager limiting law. Frictional interpretations are more explicit. The main factor contributing to the experimental diffusion coefficient for ions, Dii, remains ion-water friction which amounts to some 90 % for many slats even at 3.0 mol dm–3. The primary cause is that interionic friction between ions of opposite charge is largely cancelled by isotope–isotope friction in the expression for Dii.