Alkaline Earth Chlorides Research Articles

Optical Basicity for Understanding the Lewis Basicity of Chloride Molten Salt Mixtures.

Currently, there is a lack of reliable measurement techniques for understanding the basicity of molten chloride salts. Optical basicity, an ultraviolet-visible (UV-vis) spectroscopic method for measuring Lewis basicity, is explored for its applicability to molten chloride salts. Shifts in probe ion (Pb2+ and Bi3+) electronic transitions are observed that show that cations in chloride salts follow the same basicity series as in oxide melts, and an increase in basicity is observed with increasing temperature. Pb2+ and Bi3+ are validated as effective probe ions in alkali, alkaline earth, and aluminum-sodium chloride molten salts. However, the utility of Bi3+ is limited by the volatility of BiCl3 at high temperatures, posing a challenge for use in high-temperature molten salt applications. Since optical basicity measures the extent of electron donation, it may be a useful metric for electrochemical corrosion.

Eu2+ doped cesium alkaline earth chloride nanocrystals in glass for X-ray imaging

High-performance and low-cost metal halide perovskite scintillator materials have important applications in X-ray detection and imaging. However, large-sized perovskite scintillator panel with high transmittance, low toxicity and long-term stability is still lacking. Herein, Eu2+ doped cesium alkaline earth chloride nanocrystals (Eu2+: CsCaCl3, Eu2+: CsSrCl3, and Eu2+: Cs2BaCl4 NCs) embedded in glasses through conventional melt-quenching and subsequent heat-treatment were developed. These NCs doped glasses exhibited highly efficient and narrowband photoluminescence in blue region. Benefitting from the large X-ray absorption coefficient and high photoluminescence quantum yied, these Eu2+: CsCaCl3 NCs doped glass scintillator shows light yield of ∼9300 photons/MeV, detection limit of ∼213.8 μGy/s, and spatial resolution of 30.0 lp/mm. These results demonstrated that glasses containing Eu2+ doped cesium alkaline earth chloride nanocrystals are promising for X-ray detection and imaging.

Determination of Trace Levels of Fenbendazole in Milk, Yogurt and Curd Using Surface Enhanced Raman Spectroscopy (SERS)

A simple, rapid and sensitive surface enhanced Raman spectroscopy (SERS) method is described for the determination of fenbendazole (FBZ) residues in milk and fermented dairy products using yogurt and curd as examples. An extraction method was used to purify the samples from interfering components of the matrix. 5-Nitrothiabendazole, which has similar physicochemical properties, was used as an internal standard. The detection limits for milk were 1.8 nM, 8.8 nM for yogurt, and 13.5 nM for curd. Using partial least squares (PLS), a calibration model was built for the determination of fenbendazole from 100 to 1000 nM. The root-mean square error of calibration (RMSEC) and the root-mean square error of prediction (RMSEP) were 39.4 and 46.5 nM, respectively. The recovery rate was from 97% to 120% and the relative standard deviation was less than 5.0%. The difference between this technique from the widely used liquid chromatography–mass spectrometry (LC–MS) method is in the reduction in time for preliminary sample preparation and significantly lower costs for reagents and consumables. The article examines the influence of order when mixing reagents in a SERS experiment, which is an important tool for optimizing the sensitivity and reproducibility of the method. It was shown for the first time that when various alkaline earth metal chlorides were used for agglomeration of silver nanoparticles (AgNPs), a change in the ratio of peak intensities of the two analytes in the solution was observed. This phenomenon may be used to increase the selectivity of SERS analysis of multicomponent samples.

Surface activity and micellization of streptomycin sulfate and diphenhydramine hydrochloride in the presence of alkali and alkaline earth metal chlorides

ABSTRACT The study investigated the surface tension of the surface-active drugs streptomycin sulfate and diphenhydramine hydrochloride using three uni-univalent and three bi-univalent electrolytes: NaCl, KCl, and RbCl (0.01 mol.kg−1), and MgCl2, CaCl2, and SrCl2 (0.002 mol.kg−1) over a temperature range of 298.15 to 313.15 K. Surface tension determination has proven instrumental in examining the micellization and surface-active properties of these drugs in the presence of specific electrolytes. The surface tension values of these drugs exhibit a decrease in magnitude with increasing drug concentration, particularly noticeable in streptomycin sulfate. This phenomenon can be elucidated by considering the delicate balance between hydrophobic and hydrophilic forces within the system. Additionally, the impact of the nature of metal halides and temperature on surface tension magnitude has been scrutinised, with interpretations focused on alterations in size. From surface tension values, the interfacial parameters, such as Γ max , A min , and π CMC were examined. The results indicate a strong affinity between drug-electrolyte molecules that reduces the surface tension values. The CMC relations govern the hydrophobic and hydrophilic interactions in the ternary system of water-drug-electrolyte. The thermodynamics of micellization explains the work done for micellization and illuminates the surface and bulk properties of drugs.

Prediction of ternary alkaline-earth metal Sn(II) and Pb(II) chlorides with potential applications as p-type transparent conductors.

Non-metallic Sn(II) and Pb(II) compounds, particularly those with p-type properties, are essential functional materials due to their notable electronic arrangement and chemical characteristics. The presence of additional Sn(II) and Pb(II) chlorides is suggested by the existence of known Sn(II) and Pb(II) compounds. By utilizing first-principles calculations and swarm intelligence structure search techniques, we have predicted the existence of up to seven new ternary alkaline-earth metal chlorides: ABCl4 (where A = Sr and B = Sn or Pb) and AB2Cl6 (where A = Mg, Ca, or Ba and B = Sn, or A = Ca or Sr and B = Pb). These seven chlorides are in the divalent state. The interaction between Sn-5s (or Pb-6s) and Cl-3p in these compounds creates an anti-bonding effect in the upper valence bands, which enhances defect tolerance and promotes high p-type conductivity. These stable chlorides exhibit notable electronic properties, including wide band gaps ranging from 3.91 to 4.94 eV, broad hole effective masses ranging from 0.93 to 5.62 m0, and high valence band alignments ranging from 6.83 to 8.38 eV under vacuum. In particular, Ca/BaSn2Cl6 and CaPb2Cl6 have the potential to be used as p-type transparent conductors due to their favorable properties, including a lower hole effective mass (0.93 m0 for CaPb2Cl6) and higher ionization potentials (6.83/7.05 eV for Ba/CaSn2Cl6). Furthermore, the predicted CaPb2Cl6 crystal exhibits attenuated negative linear compressibility and negative zero-linear-compressibility along the c-axis in different pressure ranges due to its wine-rack structure. This report highlights potential applications for alkaline-earth metal Sn(II) and Pb(II) chlorides, including their use as transparent conductors, particularly p-type conductors.

Structural and dynamical properties of concentrated alkali- and alkaline-earth metal chloride aqueous solutions.

Concentrated ionic aqueous electrolytes possess a diverse array of applications across various fields, particularly in the field of energy storage. Despite extensive examination, the intricate relationships and numerous physical mechanisms underpinning diverse phenomena remain incompletely understood. Molecular dynamics simulations are employed to probe the attributes of aqueous solutions containing LiCl, NaCl, KCl, MgCl2, and CaCl2, spanning various solute fractions. The primary emphasis of the simulations is on unraveling the intricate interplay between these attributes and the underlying physical mechanisms. The configurations of cation-Cl- and Cl--Cl- pairs within these solutions are disclosed. As the solute fraction increases, consistent trends manifest regardless of solute type: (i) the number of hydrogen bonds formed by the hydration water surrounding ions decreases, primarily attributed to the growing presence of counter ions in proximity to the hydration water; (ii) the hydration number of ions exhibits varying trends influenced by multiple factor; and (iii) the diffusion of ions slows down, attributed to the enhanced confinement and rebound of cations and Cl- ions from the surrounding atoms, concurrently coupled with the changes in ion vibration modes. In our analysis, we have, for the first time, clarified the reasons behind the slowing down of the diffusion of the ions with increasing solute fraction. Our research contributes to a better understanding and manipulation of the attributes of ionic aqueous solutions and may help designing high-performance electrolytes.

High temperature corrosion of particulate matter during MSW combustion: Effects of particle size, inorganic minerals and additives on corrosion rates and mechanisms

The high temperature corrosion behavior and corrosion mitigation of PM with different sizes generated by MSW combustion were studied. The experiment result showed that the corrosion rate of 304 stainless steel increases significantly as the PM size decreases. The corrosive ability of PM1 on 304 stainless steel was about 3–5 times higher than that of PM10+ at 600 °C. Kaolin can greatly restrain the corrosiveness of PM. After 5% of kaolin was added, the corrosion rate of the PM generated by MSW combustion on 304 stainless steel was reduced by 12%. Calculating the composition of the particles after the formation of a stable slagging layer and ash deposition layer on the heating surface, the corrosion control efficiency improved to 71%. High-temperature corrosion process of PM was dominated by NaCl, KCl, CaCl2, Na2SO4 and K2SO4, the corrosion of alkali and alkaline earth chloride was generally stronger than that of sulfate at 600 °C. This study confirms that the addition of kaolin can effectively mitigate high-temperature corrosion in the superheater tubes of waste incineration furnaces.

Photo(electro)catalytic Performance of ZnO‐Based Nanopowders Prepared through Pulse Alternating Current Electrosynthesis in Alkaline Earth Chloride Electrolytes

AbstractPhoto(electro)catalysis is a technology that allows abundant and clean solar energy to be harvested as an essential step to achieving sustainable development goals. However, controllable and economically viable synthesis of nanocatalysts is one of the key challenges that hinder the practical application of many important energy‐related photo(electro)catalytic reactions. In this study insights into the electrosynthesis of ZnO‐based materials using pulse alternating current as a green oxidant and the alkaline earth metal chloride aqueous solutions as electrolytes were provided. The effect of electrolyte on composition and structure of final products was demonstrated. ZnO photocatalyst prepared in BaCl2 exhibited different activity tendency in photoelectrocatalytic and photocatalytic systems showing the highest photocurrent (0.18 mA cm−2) for ZnO photoelectrode annealed at 300 °C and maximum rate constant for methylene blue dye photodegradation in the presence of ZnO particles annealed at 500 °C. Optimized ZnO nanopowder was further employed for the degradation of 2,4‐dinitrophenol pollutant in a custom‐designed flow photoreactor operating under low‐power UV. 2,4‐dinitrophenol was degraded to 90.1 % at ZnO dosage of 0.2 mg L−1 within 280 min of illumination. Overall, the optimization of pulse alternating current electrosynthesis and post‐annealing might be promising and sustainable approach to ZnO‐based nanopowders for environmental photo(electro)catalytic applications.

Crown Ether Complexes with Alkaline Earth Metal Chlorides as Catalysts for the Decomposition of Isopropylbenzene Hydroperoxide

Crown Ether Complexes with Alkaline Earth Metal Chlorides as Catalysts for the Decomposition of Isopropylbenzene Hydroperoxide

Crown Ether Complexes with Alkaline Earth Metal Chlorides ‒ Catalysts for the Decomposition of Isopropylbenzene Hydroperoxide

Kinetic and thermodynamic parameters of the decomposition of isopropylbenzene hydroperoxide in chlorobenzene in the presence of dibenzo-18-crown-6 ether (DBK) complexes with CaCl2, SrCl2, BaCl2 have been experimentally obtained. The catalytic activity of alkaline earth metal compounds decreases in the series SrCl2·DBK CaCl2·DBK BaCl2·DBK. The formation of intermediate intermediates in the metal‒complex-hydroperoxide system has been kinetically established. SrCl2·DBK forms the strongest and most ordered structures with isopropylbenzene hydroperoxide, which decay at the highest rates. The formation of intermediate intermediates has been confirmed using quantum chemical modeling.

Role of Accumulated Alkali and Alkaline-Earth Chloride Salts in Hydrochar Formation Produced from Lignocellulosic Biomass

Hydrothermal carbonization (HTC) is an effective method for recovering useful carbon-rich solids from biomass and wet organic waste. This study investigated the effects of the type and amount of alkali and alkaline-earth chloride salts (AAECS) in HTC media on the properties of cornstalk hydrochar by analyzing the yield, elemental composition, surface functionality, and morphology, as well as fuel characteristics. The results suggest that the abundance of AAECS in HTC media may increase the aromaticity and energy recovery of hydrochar by facilitating the dehydration and decarboxylation of biomass. Both anions and cations in AAECS are responsible for these variations, especially for Ca2+, which can selectively affect the dehydration reaction of biomass by promoting the formation of anhydride and inhibiting the reaction between carboxyl and hydroxy to form a lactone. In addition, the high concentration of AAECS in HTC media is beneficial for improving the electron-donating capacity of hydrochar. This work could provide important insights into AAECS’ effects on hydrochar preparation, which arose from the recirculation of HTC aqueous solution.

Phase Equilibria in Alkaline-Earth Metal Nitrate or Chloride–Sodium Formate–Water Systems

Phase Equilibria in Alkaline-Earth Metal Nitrate or Chloride–Sodium Formate–Water Systems

Improving the tolerance to alkali and alkaline earth metal chlorides of WO3 and Nb2O5 promoted V2O5/TiO2 catalysts for the NH3-SCR reaction

V2O5-WO3/TiO2 catalysts are widely used to reduce NOx emissions from municipal solid waste incineration. However, the flue gas always contains different alkali and alkaline earth metal chlorides. In this work, we compared the effect of KCl, NaCl and CaCl2 on V2O5-WO3/TiO2 catalyst for the NH3 Selective Catalytic Reduction of NOx, and we aim to improve the tolerance of the catalyst by replacing WO3 with Nb2O5. It was found that KCl has the greatest poisoning effect, resulting in a severe decrease in the surface acidity, redox performance, V5+/V4+ ratio and surface adsorbed oxygen. The replacement of WO3 with Nb2O5 improved the activity and KCl tolerance of the catalyst owing to the improvement of surface acidity, redox performance, V5+ ratio and surface adsorbed oxygen. This may be due a more favorable interaction of K+ with Nb2O5 than with V2O5. In-situ DRITFS experiments showed that alkali (and alkaline earth) metal ions favor the transformation of adsorbed NO2 species into stable nitrates and nitrites. However, the replacement of WO3 with Nb2O5 would inhibit the formation of these stable species owing to an electronic effect of the promoter.

Pitting Propagation Behavior on Low Alloy AISI 4130 (UNS G41300) Steel Exposed to Various Alkaline Earth Metal Chlorides Using the 1-D Pit Method

This study examined pit propagation to elucidate whether alkali and alkaline earth metal chloride saltssuch as RbCl affect pitting behavior in distinctly different manner than NaCl. Pit propagation studies were conducted on a low alloy steel using one-dimensional (1-D) pit method over pit depths from 300-1000 µm. LSV and EIS of planar electrodes of 4130 in a range of Cl- solutions were conducted and revealed no differences in impedance, open circuit, corrosion potential (Ecorr), passive current density (ipass), and pitting potential (Epit) as a function of salt type. In the case of one-dimensional pits during fast downward scan rates, the saturation potential (Esat) varied as a function of salt type and pit depth when pits were shallow. Mass transported limited current density also differed with salt type in shallow pits when other alkali metal and alkaline metal cations where present. The pit surface potential (Esurf) of activated pit surfaces reached Ecorrprior to establishing a condition where the pit electrolyte surface concentration (Csurf) was less than the critical concentration for active acidified pitting (Csurf<Ccrit) in this marginally passivating steel. For various Esurf and pit current density (ipit) combinations at constant Csurf where Ccrit< Csurf < Csat, E-log(i) plots were constructed using the method of Li, Tianshu to create IR ohmic voltage corrected Tafel plots at fixed pit solution concentrations. Under these conditions, the influence of salt identity on charge transfer controlled kinetics was reexamined and slight differences in Tafel behavior were found. Differences in metal cations exert no effect on passive planar electrodes and only effect pit propagation stage in shallow pits.

(INVITED)Synthesis and luminescence properties of M(AlCl4)2:Eu2+ (M = Ca, Sr, Ba) a promising new Class of Eu2+ containing phosphors

In this work, the luminescence properties of Eu2+ doped in the host lattices M(AlCl4)2 (M = Ca, Sr, Ba) have been studied for the first time. The host compounds crystallize in a tetragonal (Ca), an orthorhombic (Sr) and a monoclinic (Ba) crystal structure where the alkaline earth site is 8-fold coordinated by Cl− ions in all cases. Therefore, these materials are ideal candidates to investigate structure related luminescence properties of Eu2+ ions. The emission spectra of the Eu2+ doped compounds are characterized by broad 4f65d1 → 4f7 transition bands located in the UV range between 388 nm and 400 nm (25773 - 25000 cm−1). Their maxima are blue shifted compared to the binary alkaline earth chloride hosts which can be explained by the influence of the [AlCl4]- ion on the crystal field splitting in addition to increasing metal-ligand distances. This shifts the lowest excited 5d level of Eu2+ to much higher energies. Furthermore, Huang-Rhys factors S and coupled phonon energies ħω were determined by temperature dependent emission measurements. In addition, radiative decay times at 10 K were determined.

NH3 Adsorption Performance of Silicon-Supported Metal Chlorides

Alkaline earth metal chlorides (AEMH) are considered to be the key to effectively solving the problem of NH3 storage due to their ability to react with NH3 to form stable ammonia complexes. This study attempted to investigate the NH3 adsorption performance of four metal chlorides (CuCl2, MnCl2, MgCl2, and CaCl2) and silicon-supported composite adsorbents with a fixed bed. The adsorbents were characterized by X-ray diffraction, Brunauer–Emmett–Teller, and scanning electron microscopy to analyze the NH3 adsorption behavior. The experiment found that the NH3 adsorption capacity of four metal chlorides is in order: CuCl2 > MnCl2 > MgCl2 > CaCl2, and the adsorption capacity of metal chlorides decreased with the increase in temperature. In addition, the composite adsorbents of silicon-supported metal chlorides were synthesized by the wet impregnation method. Ammonia adsorption experiments showed that silicon can significantly improve the NH3 adsorption capacity of metal chlorides, and the NH3 adsorption capacity of MnCl2/silicon was 127.5% higher than that of MnCl2. Silicon played the role of the skeleton support in the metal chloride particles, hindering the agglomeration between particles and increasing the number of pores on the surface of the particles, which was conducive to the diffusion of NH3 through the pores into the particles for adsorption.

Modeling dynamic viscosities of multi-component aqueous electrolyte solutions containing Li+, Na+, K+, Mg2+, Ca2+, Cl−, SO42− and dissolved CO2 under conditions of CO2 sequestration

Two accurate models were developed by this study for dynamic viscosities of multi-component aqueous electrolyte solutions containing Li+, Na+, K+, Mg2+, Ca2+, Cl−, SO42− and dissolved CO2 under conditions of CO2 sequestration. The first model is constructed by extending the Mao–Duan model for viscosities of binary aqueous solutions (aqueous single electrolyte solutions) of alkali-chloride to binary solutions of alkaline-earth chlorides, common sulfate and CO2 and combining it with Hu's mixing rule to model viscosities of multi-component solutions. The second model is constructed by improving the Goldsack–Franchetto model based on the Eyring's absolute rate theory to account for the effect of temperature on viscosity. The forms of both models are simple.Comparisons of calculations of the two models with experimental viscosity data show that both models can well represent dynamic viscosities of aqueous single electrolyte solutions and aqueous CO2 solutions at temperatures from 273 K to temperatures higher than 473 K, and at pressures from 0.1 MPa to 100 MPa. Furthermore, the two models can predict viscosities of aqueous NaCl solutions with dissolved CO2, brine containing Li+, Na+, K+, Mg2+, Ca2+, Cl−, SO42− and seawater over a wide P-T range. The absolute average deviations of the two models from most of experimental data sets are less than 2%.

One-Step Solvometallurgical Process for Purification of Lithium Chloride to Battery Grade

The use of lithium in manufacturing of lithium-ion batteries for hybrid and electric vehicles, along with stringent environmental regulations, have strongly increased the need for its sustainable production and recycling. The required purity of lithium compounds used for the production of battery components is very high (> 99.5%). In this work, a solvometallurgical process that exploits the differences in solubility between LiCl and other alkali and alkaline-earth chlorides and hydroxides in ethanolic solutions has been investigated for the purification of LiCl to battery grade at room temperature. A closed-loop flowsheet based on the green solvent ethanol is proposed for purification of LiCl, a precursor for battery-grade LiOH·H2O. High-purity LiCl solution (> 99.5% Li) could be obtained in a single-process step comprising the simultaneous selective dissolution of LiCl and the precipitation of Mg(OH)2 and Ca(OH)2 using LiOH·H2O in 95 vol% ethanol. However, the analogous process in aqueous solution resulted in impure LiCl (typically less than about 75%).Graphical

Pitting Propagation Behavior on Low Alloy AISI 4130 (UNS G41300) Steel Exposed to Various Alkali and Alkaline Earth Metal Chlorides

This study examined pit propagation to elucidate whether alkali and alkaline earth metal chloride salts such as RbCl affect pitting in some manner previously not expected compared to NaCl. Pit propagation studies were conducted on low alloy steel using one-dimensional (1D) pit method over pit depths from 300 µm to 1,000 µm. Linear sweep voltammetry and electrochemical impedance spectroscopy on planar 4130 electrodes over a range of Cl− concentrations revealed no differences in impedance, open circuit, corrosion potential (Ecorr), passive current density (ipass), and pitting potential (Epit) as a function of salt type. In the case of 1D pits evaluated during fast downward scan rates, the saturation potential (Esat) varied as a function of salt type and at shallow pit depths. Mass transported limited current density also varied with salt type in shallow pits when other alkali metal and alkaline metal cations where present. The potential (Esurf) of activated pit surfaces reached Ecorr prior to establishing a condition where the pit electrolyte surface concentration (Csurf) was less than the critical concentration for active acidified pitting (Csurf &amp;lt; Ccrit) in this marginally passivating steel. For various Esurf and pit current density (ipit) combinations at constant Csurf where Ccrit &amp;lt; Csurf &amp;lt; Csat, E-log(i) plots were constructed using the method of Li Tianshu to unmask IR ohmic voltage corrected Tafel plots at fixed pit solution concentrations. Under these conditions, the influence of salt identity on charge-transfer-controlled kinetics was re-examined and slight differences in Tafel behavior were found. Differences in metal cations have little effect on passive planar electrodes and only affect pit propagation stage in shallow pits.

Ion-induced agglomeration of Ag NPs for quantitative determination of trace malachite green in natural water by SERS

This article covers a simple one-step method that has been developed for ion-induced activation/agglomeration of silver nanoparticles. While using this method in Surface-enhanced Raman spectroscopy (SERS) we have recorded high values of signal enhancement factor (EF= 3.9 ×106). An important feature of the method is high stability of analytical signal (RSD of about 2% with analyte concentration at 1 ppb). We have shown, that in case of activation of nanoparticles with chlorides of alkaline earth metals the signal amplification proceeds according to a different mechanism rather than in case of NaCl. It was found that the synergistic action of two-charged cations (Ca2+, Mg2+, Ba2+) and chloride ions leads to the agglomeration of silver nanoparticles and the formation of “hot spots”, whereas in the case of NaCl at a concentration of up to 1 mM, only the surface modification of Ag NPs occurs. Kinetic studies have been carried out, and the mechanism of this process has been proposed. The obtained data served as a basis for the development of a simple and sensitive express method for the determination of trace amounts (in the range of 0.1–10 ppb, LOD = 0.002 ppb) of malachite green in water from natural sources. In order to compensate matrix effects we applied a standard addition method which simplified considerably the sample preparation process, increased method’s accuracy and reduced the time of analysis.