Complex Salt Research Articles

High-pressure intrusion of double salt aqueous solution in pure silica chabazite: searching for cation selectivity

Heterogeneous lyophobic systems (HLSs), i.e. systems composed of a nanoporous solid and a non-wetting liquid, have attracted much attention as promising candidates for innovative mechanical energy storage and dissipation devices. In this work, a new HLS based on a pure silica chabazite (Si-CHA) and a ternary electrolyte solution (KCl + CaCl2) is studied from porosimetric and crystallographic points of view. The combined approach of this study has been fundamental in unravelling the properties of the system. The porosimetric experiments allowed the determination of the energetic behaviour, while high-pressure in situ crystallographic analyses helped elucidate the mechanism of intrusion. The results are compared with those obtained for systems involving the same zeolite but intruded with solutions containing only single salts (CaCl2 or KCl). The porosimetric results of the three Si-CHA systems intruded by simple and complex electrolyte solutions (KCl 2 M, CaCl2 2 M and the mixture KCl 1 M + CaCl2 1 M) suggest that the intrusion pressure is mainly influenced by the nature of the cations. The CaCl2 2 M solution shows the highest intrusion pressure and KCl 2 M the lowest, whereas the mixture KCl 1 M + CaCl2 1 M is almost in the middle. These differences are probably related to the higher hydration enthalpy and Gibbs energy of Ca2+ compared with those of K+. It has been demonstrated that partial ion desolvation is needed to promote the penetration of the species, and a higher solvation energy requires higher pressure. The `intermediate' value of intrusion pressure shown by the complex electrolyte solution arises from the fact that, statistically, the second/third solvation cation shells can be assumed to be partially shared between K+ and Ca2+. The stronger interaction of Ca2+ with H2O molecules thus also influences the desolvation of K+, increasing the pressure needed to activate the process compared with the pure KCl 2 M solution. This is confirmed by the structural investigation, which shows that at the beginning of intrusion only K+, Cl− and H2O penetrate the pores, whereas the intrusion of Ca2+ requires higher pressure, in agreement with the hydration enthalpies of the two cations.

Quantitative analysis on the impact factors of salt weathering for sandstone grottoes along Silk Road, China

A large number of exquisite sandstone grottoes remaining along the Silk Road in Northwest China suffer from severe salt damage due to the vulnerability of the sandstone materials used and long-term continuous fluctuation of environmental conditions. Exploring the mechanism of salt weathering is crucial for the conservation of these grottoes. This study aims to quantitatively analyze the damage potential and the main impact factors of salt weathering in 14 grottoes along the Silk Road that were selected and investigated by using visual evaluation, salt analysis including thermodynamic modeling, and a comprehensive evaluation based on the entropy weight method. The results indicate that salt weathering of the sandstone grottoes is primarily characterized by efflorescences, peeling, and powdering. The overall salt content within the weathering layer typically exceeds a threshold of 1 %. Within the semi-arid area, the humidity fluctuations critical for significant volume changes in crystalline salts fall within the ranges 46–76 % and 16–30 %. In the semi-humid area, these ranges are 58–90 %, 42–50 %, and 16–30 %. A total of 14 salts can precipitate in the study area with NaCl, NaNO3, KNO3, Na2SO4·xH2O and several double salts occuring most frequently. Generally, the damage degree of sandstones grottoes in the semi-humid area is more serious than that in the semi-arid area. Through a comparison of visual inspection and more comprehensive quantitative evaluation, it has been confirmed that the salt damage is primarily influenced by the factors salt content, salt type, and environmental conditions. Furthermore, the order of influence for each factor on salt weathering can be ranked as follows: salt content > salt type > environmental conditions. This study quantitatively reveals the impact of various factors on salt weathering and proposes a method to evaluate the salt damage potential, which is of great significance for the preventive conservation of sandstone grottoes.

Advantages and disadvantages of barium oxide addition to bimetallic Pd-Rh three-way catalysts supported on zirconia-doped alumina

Due to enhanced high-temperature stability, zirconia-stabilized alumina is widely used as a support of three-way catalysts. The addition of barium oxide is known to improve the catalytic performance of the composition. In order to go in-depth about the effects of BaO addition, a series of samples was prepared using nitrates and complex salts as a precursor. The interaction of BaO with alumina was found to change dramatically the metal-support interaction of the latter with metals. Thus, the presence of BaO resulted in the sintering of Pd with the formation of agglomerated Pd0 species, which explains a lower activity in CO oxidation of the BaO-doped samples after thermal treatment. Contrarily, the addition of barium nitrate showed a positive effect, inhibiting the collapse of the porous structure of the support, which was the most crucial and accompanied by the formation of the α-Al2O3 phase when no barium nitrate was added.

Fabrication and characterization of Zn-hydroxy double salt-loaded composite: Antimicrobial and flame-retardancy properties

Herein, a novel versatile composite comprising Zn-hydroxy double salt (ZnHDS) and tannic acid (TA) fillers within a polyvinyl alcohol-polyethylene imine (PVA-PEI) mixed matrix (ZnHDS-TA@PVA-PEI) was fabricated and characterized. This composite exhibited dual functionality as an antimicrobial agent and a flame retardant. The composite exhibited significant antimicrobial activity against E. coli and S. aureus strains. The incorporation of ZnHDS into TA@PVA-PEI significantly enhanced its antimicrobial efficacy and flame-retardancy. Clearing zones for the ZnHDS-TA@PVA-PEI against E. coli and S. aureus with 3.8 % ZnHDS loading were obtained as 8.5 and 5.5 mm, respectively. The ZnHDS-TA@PVA-PEI, with a 3.8 % ZnHDS loading, required 18.52 kJ/mol of energy to initiate its thermal decomposition and absorbed a net energy of 41.40 J/g during the process. The maximum weight loss rates for ZnHDS, PVA-PEI, TA@PVA-PEI, and ZnHDS-TA@PVA-PEI were 0.50, 0.75, 0.99, and 0.85 %/°C, respectively. Water solubility tests demonstrated augmented resistance to water with increasing ZnHDS content. The introduction of ZnHDS into TA@PVA-PEI significantly improved the flame-retardancy, was slow to ignite, and self-extinguished within seconds. The thermal decomposition process, antimicrobial activity, and flame-retardancy mechanisms of the composites are discussed. These results, along with the affordability, biocompatibility, and eco-friendliness of ZnHDS, revealed its potential for multiple applications.

Spectroscopy of Magnesium Sulfate Double Salts and Their Implications for Mars Exploration

Magnesium sulfate has been widely detected on the surface of Mars. The occurrence of magnesium sulfate and mixed cationic sulfates preserves clues regarding the sedimentary environment, hydrological processes, and climate history of ancient Mars. In this study, seven magnesium sulfate double salts were synthesized in the laboratory using a high-temperature solid phase reaction or slow evaporation of aqueous solutions. The samples were analyzed using X-ray diffraction to confirm their phase and homogeneity. Subsequently, the Raman, mid-infrared spectra, and visible near-infrared spectra of these samples were collected and analyzed. Our results showed that the spectra of the analyzed magnesium sulfate double salts exhibited distinctive spectral features. These laboratory results may provide new insights for the identification of various magnesium sulfate double salts on Mars during the interpretation of in situ data collected by Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC), SuperCam, and the ExoMars Raman Laser Spectrometer (RLS). In addition, the MIR and VNIR spectra features obtained in this study provide an improved reference and spectra library for decipherment of data sourced from the Thermal Emission Spectrometer (TES), Thermal Emission Imaging System (THEMIS), and Mars Mineralogical Spectrometer (MMS).

Expansion displacement mechanics model of concrete under seawater corrosion

In this study, the variation in the expansion displacement of concrete samples with different water-cement ratios under five corrosion solutions (single sulfate salt and coupled sulfate-chloride salt) is explored. The expansion displacement evolution of these concrete samples under sulfate corrosion (single salt corrosion) and sulfate-chloride corrosion (double salt corrosion) is comprehensively examined. The results reveal that the continuous accumulation of corrosion damage eventually manifests in the form of expansion displacement. Based on the experimental results and the chemical reaction rate equation of the delayed ettringite formation and Friedel’s salt generation, an evolution model of expansion force is established. According to this model and the Weibull distribution law of damage, a expansion displacement mechanics model is proposed to predict the expansion displacement behavior of concrete under sulfate corrosion as well as combined sulfate-chloride corrosion.

Synthesis of a 50-electron triangular ruthenium cluster containing a μ3-methylidyne ligand via the fragmentation of the Ru2 skeleton

A chloride salt of cationic triruthenium complex containing a μ3-methylidyne ligand, [{Cp*Ru(μ-Cl)}3(μ3CH)]+ (4; Cp* = η5-C5Me5)), was synthesized by the reaction of diruthenium tetrahydrido complex [Cp*Ru(μ-H)4RuCp*] (1) with chloroform in 91% yield. Although 4 contains a 50-electron configuration, an X-ray diffraction study of a tetraphenylborate salt of 4 demonstrated that 4 has a closed-triangular triruthenium skeleton with a Ru−Ru distance of ca. 2.87 Å, which is considerably longer than the Cl-bridged Ru−Ru distance in the related 48-electron μ3-methylidyne complex, [(Cp*Ru)3(μ3CH)(μ-Cl)2(μ-H)]+ (5; 2.757(1) Å). Complex 4 was also obtained by the reaction of triruthenium pentahydrido complex [{Cp*Ru(μ-H)}3(μ3H)2] (2) with CHCl3, and crossover experiments using 2 and [{CpEtRu(μ-H)}3(μ3H)2] (2-Et3; CpEt = η5-C5EtMe4) demonstrated that the cluster skeleton of 2 was broken during the reaction. These results are contrasted with the exclusive formation of dinuclear μ-chloromethylidyne complex, [(Cp*RuCl)2(μ-CCl)(μ-Cl)] (3), by the reaction of 1 with CCl4, and the number of nuclei of the product is suggested to be determined by the substituent at the methylidyne carbon. Although a triruthenium complex was not formed by the reaction of 3 with [Cp*RuCl]4, a heterobimetallic trinuclear μ3-methylidyne complex, [(Cp*Ru)2(Cp*Ir)(μ3CH)(μ-Cl)(μ-H)2] (9) was obtained by the reaction of 3 with [Cp*IrH4] along with substitution of the chloromethylidyne ligand by a hydride.

Preparation, thermal properties, and structures of ionic plastic crystals with sandwich and half-sandwich Ru complexes

We have recently been investigating the phase behavior of salts of cationic sandwich complexes in pursuit of novel ionic plastic crystals (IPCs). In this study, we synthesized salts containing sandwich complexes [Ru(Cp)(C6H6)]X ([1]X; X = CPFSA− (1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide), SbCl6−) and half-sandwich complexes [Ru(Cp)(DMSO)3]X ([2]X; X = CPFSA−, FSA− ((FSO2)2N−), PF6−). In addition, we examined their thermal properties and crystal structures. Among them, [1]CPFSA exhibited an IPC phase between 365 and 630 K, whereas the others did not undergo phase transitions at 123–403 K. The cations and anions were alternately arranged in the crystals of [1]X, whereas [2]X did not exhibit the alternating arrangement except for [2]PF6. The results showed that alternating molecular arrangements are crucial for the IPC formation, although low symmetry of the ion environment and intermolecular steric hindrance may inhibit it.

Introduction of photochromic properties to UiO-66-NH2 via “click”-modification by spiropyran molecule

We present a study on incorporating spiropyran photoactive molecules into the UiO-66-NH2 scaffold. Initially, we modified spiropyran molecules by introducing functional groups to facilitate covalent bonding with the MOF structure. Spiropyran molecules with carboxylic groups demonstrated the ability to coordinate zirconium in defect pores of the MOF. Alternatively, the aldehyde group showed potential for forming C–N bonds with amino groups of BDC-NH2 linkers. To validate the formation of C–N bonds within the MOF scaffold, we synthesized a complex salt of spiropyran and individual BDC-NH2 linkers. DFT calculations support our conclusions. We observed that upon introducing the photoactive moiety, the UiO-66-NH2 framework exhibited photoresponse, as demonstrated by FTIR experiments. Based on experimental data and computational results, we hypothesize that both incorporation mechanisms are viable in the functionalization process. However, steric hindrances may impede the incorporation of spiropyran into the pores, leading to surface modification instead. The elucidated mechanisms hold promise for the development of photoresponsive MOF-based smart materials.

Механические свойства композиции на основе полиэфирной смолы с частицами оксида меди (I)

The mechanical properties of polyester resin composition with copper (I) oxide dispersed filler particles (non capsulated, capsulated by polylactide, and dissolved by the resin components) are considered in that paper. It was showing that a capsulated filler particle has better interaction with polymer matrix than non capsulated particles. So, the tensile strength and hardness of PCM are increasing, but ultimate deformation is decreasing. The strength characteristics of PCM with partial dissolution of copper (I) oxide particles by the components of the polyester resin was decrease. The density of the polymer binder network due to the loss of styrene, as well as the formation of complexes of copper salts are the cause of strength characteristics decrease.

Molecular and electrostatic origins of mixed salt partitioning phenomena in uncharged poly(ethylene oxide)-based membranes

Despite the increasing interest in membranes for water purification and resource recovery from aqueous electrolyte mixtures, few studies rigorously investigate the influence of salt solution composition (e.g., mole fraction and total salt concentration) on membrane material properties such as partition coefficients. Here, we systematically investigate the influence of solution composition on the partitioning of ionic species from binary aqueous salt solutions into crosslinked poly(ethylene glycol) diacrylate membranes at fixed ionic strength. These results are compared to partition coefficients observed for pure salt solutions. We observe large systematic deviations between the pure salt and mixed salt ion partition coefficients, indicating that the single salt partition coefficients that are often reported do not describe the more complex and realistic mixed salt scenario. Free energy calculations from molecular dynamics simulations, coupled with equilibrium thermodynamic modeling, indicate that mixed salt partitioning trends result from (i) different ions exhibiting different affinities for the membrane and (ii) the constraint of global electrical neutrality within the membrane. With this physical insight, we develop a simple approach to predicting the concentration of various ions in a membrane equilibrated with a mixed salt solution which requires no adjustable parameters.

Heterogeneous Structure, Mechanisms of Counterion Exchange, and the Spacer Salt Effect in Complex Molten Salt Mixtures Including LaCl3.

Complex molten chloride salt mixtures of uranium, magnesium, and sodium are top candidates for promising nuclear energy technologies to produce electricity based on molten salt reactors. From a local structural perspective, LaCl3 is similar to UCl3 and hence a good proxy to study these complex salt mixtures. As fission products, lanthanide salts and their mixtures are also very important in their own right. This article describes from an experimental and theory perspective how very different the structural roles of MgCl2 and NaCl are in mixtures with LaCl3. We find that, whereas MgCl2 becomes an integral part of multivalent ionic networks, NaCl separates them. In a recent article (J. Am. Chem. Soc. 2022, 144, 21751-21762) we have called the disruptive behavior of NaCl "the spacer salt effect". Because of the heterogeneous nature of these salt mixtures, there are multiple structural motifs in the melt, each with its particular free energetics. Our work identifies and quantifies these; it also elucidates the mechanisms through which Cl- ions exchange between Mg2+-rich and La3+-rich environments.

Reductions of Arenes using a Magnesium-Dinitrogen Complex.

In this contribution, we present "Birch-type", and other reductions of simple arenes by the potassium salt of an anionic magnesium dinitrogen complex, [{K(TCHPNON)Mg}2(μ-N2)] (TCHPNON = 4,5-bis(2,4,6-tricyclohexylanilido)-2,7-diethyl-9,9-dimethyl-xanthene), which acts as a masked dimagnesium(I) diradical in these reactions. This reagent is non-hazardous, easy-to-handle, and readily provides access to 1,4-cyclohexadiene reduction products under relatively mild reaction conditions. This system works effectively to reduce benzene, naphthalene and anthracene through magnesium-bound "Birch-type" reduction intermediates. Cyclohexadiene products can be subsequently released from the magnesium centres by protonolysis with methanol. In contrast, the reduction of substituted arenes is less selective and involves competing reaction pathways. For toluene and 1,3,5-triphenylbenzene, the structural authentication of "Birch-type" reduction intermediates is conclusive, although the formation of corresponding 1,4-cyclohexadiene derivatives was low yielding. Reduction of anisole did not yield an isolable "Birch-type" intermediate, but instead gave a C-O activation product. Treating triphenylphosphine with [{K(TCHPNON)Mg}2(μ-N2)] resulted in the extrusion of both biphenyl and dinitrogen to afford a magnesium(II) phosphanide [{K(TCHPNON)Mg(μ-PPh2)}2]. Reduction of fluorobenzene proceeded via C‒F activation of the arene, and isolation of the magnesium(II) fluoride [{K(TCHPNON)Mg(μ-F)}2]. Finally, the two-electron reduction of 1,3,5,7-cyclooctatetraene (COT) with [{K(TCHPNON)Mg}2(μ-N2)] yielded a complex, [{K(TCHPNON)Mg}2(μ-COT)], incorporating the aromatic dianion (COT2-).

Surface confinement–induced electrochemiluminescence enhancement of Au nanoclusters for ultrasensitive detection of a soluble urokinase-type plasminogen activator receptor

In this study, gold nanoclusters (Au NCs) anchored on the surface of 2D Zn-containing hydroxyl double salt (Zn-HDS) with surface confinement–induced electrochemiluminescence (SC-ECL) improvement were used as an intensive ECL emitter to construct a biosensor for ultrasensitive detection of soluble urokinase-type plasminogen activator receptor (suPAR) related to cardiovascular disease in chronic nephritis patients. Impressively, SC-ECL of Au NCs/Zn-HDS nanocomposites exhibited fast electrochemical excitation and efficient radiation transition, showing 4.9 times stronger ECL emission and 10.9 times higher ECL efficiency than those of pure Au NCs. This improvement was attributed to the matched energy level of Zn-HDS and Au NCs, enabling electron–hole pairs of Au NCs to be trapped by the energy levels of Zn-HDS. Moreover, a bipedal DNA walker was generated through target-induced DNA strand displacement and catalytic hairpin assembly (CHA), which was attached to a stable DNA cubic track through electrostatic attraction of positively charged SH-PEG-NH3+ to improve walking efficiency and further boost detection sensitivity. Consequently, the proposed sensing platform achieved trace detection of suPAR ranging from 0.700 pg/mL to 80.0 ng/mL with a low detection limit of 0.344 pg/mL and was successfully applied to detect suPAR in patient serum. This work synthesized a highly efficient metal nanocluster-based ECL emitter, showing great potential in constructing ultrasensitive biosensors for early disease diagnosis.

Photo‐controllable cationic homopolymerization and random copolymerization of vinyl ethers based on iridium salt photocatalyst

AbstractTemporal control of chain growth is a central challenge for photoinitiated active polymerization. In this work, we introduced an iridium salt complex‐based catalyst system to achieve fine temporal control of the chain growth process. By electrochemical analysis, compared with the pyran salt photocatalyst, it was found that the iridium salt complex could promote the chain transfer of active species to reversible addition‐fragmentation chain transfer polymerization (RAFT) reagent, thereby generating dormant species, which provided the possibility of time control of the polymerization process. Using this catalytic system, we successfully achieved homopolymerization of vinyl ethers with different substituents and random copolymerization with isobutyl vinyl ethers, which is not only pointed the way for broadening the monomer selection in the future, but also provided an innovative way to prepare new functionalized materials.

Dissolution of cellulose in imidazolium-based double salt ionic liquids

The dissolution of cellulose in double salt ionic liquids (DSILs) was studied in detail and compared with the dissolution in individual constituent ionic liquids (ILs). The DSILs, [C4mim](CH3CO2)xCl1-x (x is the mole fraction of the single component ILs), were synthesized using acetate and chloride salts of 1-butyl-3-methylimidazolium. These DSILs were then used for the investigation of the solubility of cellulose in the whole mole fraction range. Commercial cellulose (CC) powder, kraft pulp (KP), and prehydrolysis kraft pulp (PHKP) of jute were chosen as cellulose sources. The solubility of cellulose increased with an increasing temperature for [C4mim](CH3CO2)0.6Cl0.4 and with increasing amount of [C4mim]Cl in DSILs. The maximum solubility of CC powder was 32.8 wt% in [C4mim](CH3CO2)0.6Cl0.4 at 100 °C, while for KP and PHKP, solubilities were 30.1 and 30.5 wt% respectively under the identical condition. Cellulose could be regenerated from the DSILs using water as an antisolvent. Structure, morphology, and thermal stability of the regenerated cellulosic materials were analyzed. Cellulose could be recycled >99 % without a discernible change in structure. This work demonstrates that DSILs display enhanced solubility over ILs system and have potential as a chemical processing methodology.

Inclusion complex of ionic liquid 1-dodecylpyridinium tetrafluoroborate with sulfobutyl ether-β-cyclodextrin: Preparation and characterization

In this article an inclusion complex of hydrophobic ionic liquid 1-dodecylpyridinium tetrafluoroborate (PyrC12-BF4) and sodium salt of sulfobutyl ether β-cyclodextrin (SB-β-CD) has been synthesized and studied using NMR spectroscopy, UV–Vis spectroscopy, FT-IR, TGA, DSC and XRD. The results of 1H NMR study revealed physicochemical interactions between the hydrophobic alkyl chain of PyrC12-BF4 and protons of the inner cavity of SB-β-CD, as well as between the CH protons of pyridinium cation and the polar SB-β-CD groups. The formation of an inclusion complex has also been revealed by Wilhelmy plate method. The binding constant of the SB-β-CD/PyrC12-BF4 complex determined by the method of Higuchi and Connors was found to be 1210 M–1. According to DSC analysis data, only one endothermic peak is observed in the thermogram of the SB-β-CD/PyrC12-BF4 inclusion complex, thus confirming the formation of a new supramolecular system. Additional characterization methods such as thermal mass spectroscopy and TEM were also applied for characterization of the synthesized complex. Complexation of long-chain pyridinium salt with SB-β-CD can be an efficient approach for the preparation of new antimicrobial formulations with reduced toxicity.

Cadmium Hydroxyl Chloride with Balanced Band Gap and Second-Harmonic-Generation Response.

Ultraviolet (UV) nonlinear-optical (NLO) materials are crucial in laser technology due to their ability to modulate light frequency. In this work, when d10 cations, hydroxyl groups, and Cl atoms were combined, a cadmium double salt, Cd(OH)Cl, was synthesized by a simple hydrothermal method. It has a large phase-matched second-harmonic-generation (SHG) response at 1064 nm (2.5 × KDP) with a short UV-cutoff edge (260 nm), which can be applied in a solar-blind UV band. Theoretical calculations suggest that [Cd(OH)3Cl3] groups lead to a large SHG response. Our work may shed light on the exploration of new NLO materials in metal hydroxyl chlorides.

Determination of seawater COD spectra using double-loop contraction and sorted frog optimization.

This study develops a novel double-loop contraction and C value sorting selection-based shrinkage frog-leaping algorithm (double-contractive cognitive random field [DC-CRF]) to mitigate the interference of complex salts and ions in seawater on the ultraviolet-visible (UV-Vis) absorbance spectra for chemical oxygen demand (COD) quantification. The key innovations of DC-CRF are introducing variable importance evaluation via C value to guide wavelength selection and accelerate convergence; a double-loop structure integrating random frog (RF) leaping and contraction attenuation to dynamically balance convergence speed and efficiency. Utilizing seawater samples from Jiaozhou Bay, DC-CRF-partial least squares regression (PLSR) reduced the input variables by 97.5% after 1,600 iterations relative to full-spectrum PLSR, RF-PLSR, and CRF-PLSR. It achieved a test R2 of 0.943 and root mean square error of 1.603, markedly improving prediction accuracy and efficiency. This work demonstrates the efficacy of DC-CRF-PLSR in enhancing UV-Vis spectroscopy for rapid COD analysis in intricate seawater matrices, providing an efficient solution for optimizing seawater spectra.

Carnallite double salt for thermochemical heat storage

The potential use of carnallite (KMgCl3·6H2O) for low temperature thermochemical heat storage has been evaluated. Carnallite is an incongruently soluble double salt and its possible decomposition and dehydration reactions have been carefully evaluated from available thermodynamic data and the phase diagram has been constructed. The dehydration and rehydration reactions have been experimentally studied and the reaction products have been characterized using thermogravimetric mass spectrometry, water vapor sorption, X-ray powder diffraction, scanning electron microscopy, Raman microscopy and calorimetry. The results of the experimental investigation of these reactions confirm the model predictions and clearly show that a thermochemical cycle including carnallite and its dihydrate (KMgCl3·2H2O) is very promising for low temperature domestic thermochemical storage. In comparison to both pure MgCl2·6H2O and also other salts mentioned in the literature, the double salt carnallite offers significant advantages. It has a higher deliquescence humidity and, thus, is much less sensitive to over-hydration and liquefaction. It can be easily dehydrated at only 100 °C and is much less prone to hydrolysis (HCl release). Carnallite has also a good reversibility between dehydration and hydration and the re-formation of carnallite by rehydration is easily achieved at low water vapor pressure and faster reaction rate than the hydration of MgCl2·2H2O to MgCl2·6H2O. The enthalpy of hydration is slightly higher for the hydration of KMgCl3·2H2O than for the hydration of MgCl2·2H2O. The only price to be paid is a slightly reduced storage density of the double salt due to its larger molar volume. However, the theoretical storage density of 1.52 kJcm−3 is still excellent. Also, carnallite is a low-cost material as it is available as industrial waste material or can be easily synthesized.