Chloride Salt Mixtures Research Articles

Ionothermal Synthesis of Imide-Linked Covalent Organic Frameworks.

Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time‐consuming process and restricted to well‐soluble precursor molecules. Synthesis of polyimide‐linked COFs (PI‐COFs) is further complicated by the poor reversibility of the ring‐closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI‐COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene‐based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high‐temperature XRPD analysis hints to the formation of precursor–salt adducts as crystalline intermediates, which then react with each other to form the COF.

Ionothermal Synthesis of Imide‐Linked Covalent Organic Frameworks

AbstractCovalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time‐consuming process and restricted to well‐soluble precursor molecules. Synthesis of polyimide‐linked COFs (PI‐COFs) is further complicated by the poor reversibility of the ring‐closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI‐COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene‐based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high‐temperature XRPD analysis hints to the formation of precursor–salt adducts as crystalline intermediates, which then react with each other to form the COF.

Kinetic Parameters and Diffusivity of Uranium in FLiNaK and ClLiK

Anodic stripping voltammetry (ASV) and cyclic voltammetry (CV) measurements at 773, 823, and 873 K were made of uranium trifluoride (UF3) in lithium fluoride-sodium fluoride-potassium fluoride eutectic (FLiNaK) and uranium trichloride (UCl3) in lithium chloride-potassium chloride eutectic (ClLiK). ASV data were used to estimate the charge transfer coefficients, exchange current densities, and activation energies of the uranium reactions. Charge transfer coefficients of both salt systems were within the range of 0.17 to 0.38. Exchange current densities in the fluoride and chloride salts were estimated within the range of 0.060 to 0.12 A cm−2. Activation energy of uranium exchange current was 16.0 kJ mol−1 in the fluoride salt and 28.9 kJ mol−1 in the chloride salt. Kinetics of charge transfer were found to be faster in FLiNaK. Analyses of the CV data suggest the electrochemical system was diffusion controlled and irreversible in the chloride and fluoride salt mixtures. Diffusion coefficients of uranium in the range of temperatures were on the order of 10−5 cm2 s−1 in both systems. Greater values of diffusivity in ClLiK are attributed to its lower density compared with FLiNaK. Activation energy of uranium diffusion in the fluoride and chloride salt mixtures were 53.4 and 89.4 kJ mol−1, respectively.

Determination of the concentration of high-molecular water-soluble polymer used in the development of a new type of feed additive

High molecular weight water soluble nanoscale polymers (HWP) have different functional functions and different applications. For the first time in livestock, we applied GDP in feeding ruminants to increase their dairy and meat productivity. When developing an innovative feed additive based on nanosized anionic polymers, it is necessary to study their properties, for this purpose it is necessary to determine the presence of these polymers in aqueous solutions. Currently, there are several basic methods for determining the concentration of HWP in water. However, they have significant disadvantages, including complexity of execution, duration of the process, use of aggressive reagents, necessity to use expensive equipment. Our rapid method of quantifying anionic HWP is simple, accurate and inexpensive. The method is based on the flocculating properties of polymers. The method envisages preparation of basic and auxiliary solutions of golden ochre pigment and saturated solution of mixture of sodium and potassium chloride salts, determination of time of gold ochre pigment settling in idle test and in analysed solutions. Formulas for calculation of ochre sedimentation rate and polymer concentration are given. The method can be used in the concentration range of anionic polymers 0.0001 0.5 mg/ml. The express method is intended for specialists of chemical laboratories of industrial and agricultural enterprises, scientific and medical institutions.

Selective Photo‐Oxygenation of Light Alkanes Using Iodine Oxides and Chloride

AbstractPartial oxidation of light alkanes to generate alkyl esters has been achieved under photochemical conditions using mixtures of iodine oxides and chloride salts in trifluoroacetic acid (HTFA). The reactions are catalytic in chloride and are successful using compact fluorescent light, but higher yields are obtained using a mercury lamp. In this photo‐initiated oxyesterification process, the robust alkyl ester products are resistant to over‐oxidation, and under optimized conditions yields for alkyl ester production of ∼50 % based on methane, ∼60 % based on ethane (with a total functionalized yield of EtX (X=TFA or Cl) of 80 %) and ∼30 % based on propane have been demonstrated. The reaction also proceeds in aqueous HTFA and dichloroacetic acid with lower yields. Mechanistic studies indicate that the process likely operates by a chlorine hydrogen atom abstraction pathway wherein alkyl radicals are generated, trapped by iodine, and converted to alkyl trifluoroacetates in situ.

Hot corrosion of different alloys in chloride and carbonate molten-salt mixtures under argon atmosphere

Molten eutectic salt mixtures can be used as thermal energy storage materials or heat transfer fluids at concentrated solar power plants. The targeted operating temperature for the next generation concentrated solar power plants is 700 °C. Although chloride and carbonate eutectic salt mixtures with high thermally stable temperatures were reported to have great thermophysical properties, their corrosion to alloys at high temperature has not been thoroughly studied. Corrosion of the thermal energy storage materials and heat transfer fluids to alloys is critical, and oxygen in air is confirmed to accelerate the corrosion significantly. In the present study, three eutectic mixtures of NaCl-KCl-ZnCl2, Li2CO3-Na2CO3-K2CO3 and LiF-Na2CO3-K2CO3 were considered as high temperature thermal energy storage materials or heat transfer fluids. Corrosion of stainless steel 316, Hastelloy C276, Inconel 625 and 718 immersed in the three salt mixtures up to 21 days were experimentally investigated at 700 °C under argon atmosphere. The specimens after corrosion tests were characterized by scanning electron microscope, energy dispersive spectroscopy and X-ray diffraction. The results show that SS316 is only compatible with the LiNaK carbonate-salt and the corresponding corrosion rate is lower than 95 μm/year. Both C276 and In625 have relatively good corrosion resistance for the NaKZn chloride-salt and LiF-NaK carbonate-salt, and the corrosion rates are lower than 78 μm/year. The highest corrosion rate over 1700 μm/year is detected for In625 immersed in the LiNaK carbonate-salt. In addition, In718 shows excellent corrosion resistance less than 10 μm/year immersed in all the three salt mixtures.

Partial substitution of NaCl with chloride salt mixtures: Impact on oxidative characteristics of meat myofibrillar protein and their rheological properties

The effects of partial substitution of NaCl using chloride salt (KCl, MgCl2, and CaCl2) mixtures with different formulas on oxidative characteristics, physicochemical and gel properties of the pork meat myofibrillar protein (MP) were investigated. In a hydroxyl-radical-induced oxidative system, the mixtures of NaCl, KCl, and MgCl2 increased the carbonyl content of MP in substitution degree of 25% and 50%; and all chloride salts mixtures raised MP's disulfide bond level. In addition, chloride salt mixtures significantly lower MP gel's storage modulus, water-holding capacity, and gel strength, especially at the substituted ratio of 50%, due to the more disorderly and aggregated structure were observed in MP gels. The MP gel containing 0.45 M NaCl, 0.075 KCl, and 0.025 M MgCl2 exhibited superior qualities due to its compact pore structure. Thus, that NaCl was partially substituted by KCl and MgCl2 at a lower substituted ratio (25%) is promising to improve the functional properties of low-sodium MP gel products.

Corrosion of carbon steel underneath a lead/potassium chloride salt mixture

AbstractHigh amounts of lead in waste/recycled wood fuel are known to be a contributing factor to the increased corrosion often related to this type of fuel. In combination with potassium, usually present in the fuel, low‐melting point salt mixtures between lead chloride (PbCl 2) and potassium chloride (KCl) are expected to form. The purpose of this study is to investigate reactions in the mixed salt of PbCl 2 and KCl and its interactions with carbon steel P265GH and its oxide. Laboratory exposures were performed in an isothermal tube furnace with a salt mixture of PbCl 2/KCl (50/50 mol%) put on steel samples. The test duration was 24 hr at either 300°C or 340°C in an atmosphere of 100 ppm HCl and 20 vol% H 2O in synthetic air. After exposure, the salt mixture consists of distinct areas of KCl and PbCl 2 but also the compounds K 2PbCl 4 and KPb 2Cl 5. A general observation is that the oxide thickness increases with temperature and that areas with Pb/K‐mixed salt are frequently found in close connection to more corroded areas. Often the more lead‐rich phase KPb 2Cl 5 is located closest to the corrosion product indicating its importance for the corrosion.

Thermo-economic analysis of high-temperature sensible thermal storage with different ternary eutectic alkali and alkaline earth metal chlorides

Molten salt mixtures with alkali and alkaline earth metal chlorides were developed for high-temperature sensible thermal energy storage in support of concurrent efforts to develop high-temperature advanced power cycles for concentrating solar power applications. Four ternary chloride mixtures with different cation combinations (Na, K, Li, Mg) were designed using the FactSage® software, and for three of these, the eutectic point was experimentally validated by differential scanning calorimetry. Specific heat capacity measurements were conducted following the ASTM E1269 standard, and were measured between 1.18 J/g/K and 1.31 J/g/K. The mass loss of the molten chloride salts was studied under three different gas blankets of nitrogen, argon and air by thermogravimetric analysis. All the selected salt mixtures were stable up to 700 °C, although weight loss due to vaporisation becomes significant around this temperature due to the high vapour pressure of the chloride salt mixtures. However, it is expected that operation at a temperature up to around 750 °C will be feasible in a closed system with an inert environment. Additionally, removal of chemically-bonded water and salt purification may need to be considered for extending the operating temperature. In terms of economic performance, although the inclusion of LiCl in the ternary eutectic mixtures is advantageous for reducing melting point and increasing specific heat capacity, at current costs, these benefits are unlikely to be justified unless LiCl cost reduces by a factor of three. The NaCl-KCl-MgCl2 mixture has the lowest cost per unit energy stored, at 4.5 USD/kWh.

Comparative Physicochemical and Electrochemical Characterization of the Structure and Composition of Thin Pd Binary and Ternary Codeposits with Pt, Ru, and Rh.

Pd-Ru, Pd-Rh, Pd-Pt-Ru, and Pd-Rh-Ru electrodes were prepared as thin layers by potentiostatic codeposition or chemical co-precipitation of metals from baths containing mixtures of chloride salts. The formation of substitutional solid solutions, with lattice parameters smaller than that of pure Pd, was confirmed by X-ray diffraction (XRD). The compositions at various levels of sample volume and thickness were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and also electrochemically by cyclic voltammetry (CV) in 0.5 M H2SO4. The differences between surface, subsurface, and bulk compositions were compared for various systems in a wide composition spectrum.

Plant roots and species moderate the salinity effect on microbial respiration, biomass, and enzyme activities in a sandy clay soil

The aim of this study was to determine the effects of plant absence or presence on microbial properties and enzyme activities at different levels of salinity in a sandy clay soil. The treatments involved five salinity levels—0.5 (control), 2.5, 5, 7.5, and 10 dS m−1 which were prepared using a mixture of chloride salts—and three soil environments (unplanted soil, and soils planted with either wheat or clover) under greenhouse conditions. Each treatment was replicated three times. At the end of the experiment, soil microbial respiration, substrate-induced respiration (SIR), microbial biomass C (MBC), and enzyme activities were determined after plant harvest. Increasing salinity decreased soil microbial properties and enzyme activities, but increased the metabolic quotient (qCO2) in both unplanted and planted soils. Most microbial properties of planted soils were greater than those of unplanted soils at low to moderate salinity levels, depending upon plant species. There was a small or no difference in soil properties between the unplanted and planted treatments at the highest salinity level, indicating that the indirect effects of plant presence might be less important due to significant reduction of plant growth. The lowered microbial activity and biomass, and enzyme activities were due to the reduction of root activity and biomass in salinized soils. The lower values of qCO2 in planted than unplanted soils support the positive influence of plant root and its exudates on soil microbial activity and biomass in saline soils. Nonetheless, the role of plants in alleviating salinity influence on soil microbial activities decreases at high salinity levels and depends on plant type. In conclusion, cultivation and growing plant in abandoned saline environments with moderate salinity would improve soil microbial properties and functions by reducing salinity effect, in particular planting moderately tolerant crops. This helps to maintain or increase the fertility and quality of abandoned saline soils in arid regions.

Mechanism of Hydrocarbon Functionalization by an Iodate/Chloride System: The Role of Ester Protection

Mixtures of chloride and iodate salts for light alkane oxidation achieve >20% yield of methyl trifluoroacetate (TFA) from methane with >85% selectivity. The mechanism of this C–H oxygenation has been probed by examining adamantane as a model substrate. These recent results lend support to the involvement of free radicals. Comparative studies between radical chlorination and iodate/chloride functionalization of adamantane afford statistically identical 3°:2° selectivities (∼5.2:1) and kinetic isotope effects for C–H/C–D functionalization (kH/kD = 1.6(3), 1.52(3)). Alkane functionalization by iodate/chloride in HTFA is proposed to occur through H-atom abstraction by free radical species including Cl• to give alkyl radicals. Iodine, which forms by in situ reduction of iodate, traps alkyl radicals as alkyl iodides that are subsequently converted to alkyl esters in HTFA solvent. Importantly, the alkyl ester products (RTFA) are quite stable to further oxidation under the oxidizing conditions due to the protecti...

Rare earth chloride and nitrate salts as individual and mixed inhibitors for aluminium alloy 7075-T6 in chloride solution

ABSTRACTThe aim of the study was to investigate various rare earth salts as corrosion inhibitors of aluminium alloy 7075-T6. Rare earth salts, CeCl3, LaCl3, Ce(NO3)3 and La(NO3)3, were studied, first as individual inhibitors in the concentration range between 0.001 and 0.05 M. Second, the inhibitory effect of mixtures of chloride or nitrate salts was studied at an overall inhibitor concentration of 0.01 M. The corrosion properties of AA7075-T6 in the absence and presence of individual and mixed rare earth salts were investigated using electrochemical potentiodynamic technique in 0.1 M NaCl. The topography, morphology and composition of the inhibited surfaces were recorded. The highest inhibitory effectiveness was exhibited by CeCl3, followed by mixtures of CeCl3 and LaCl3. During immersion for 12 h the corrosion protection remained high. Nitrate rare earth salts showed less protection, both as individual or as mixed inhibitors. Deposits containing both cerium and lanthanum were formed primarily on Cu-based intermetallics.

A study on sodalite pellets as matrix for spent chloride salts confinement

ABSTRACTPellets made of pure sodalite blended with commercial glass frit and pellets made of sodalite, glass frit and a mixture of chloride salts, synthesized through dry pressing and subsequent thermal treatment, were evaluated as a potential matrix for confinement of spent chloride salts coming from pyroprocesses. The sodalite pellets were leached at 23°C and 90°C for 28 days, according to the ASTM C1220-10 procedure. Normalized release rates were estimated for the following elements: Li, Na, Al, Si, K, Rb, Cs, Sr, Ba, La, Nd and compared with literature results. SEM investigations, carried out before and after the leaching tests, show dissolution and re-precipitation phenomena at 90°C.

Fabrication and thermal conductivity improvement of novel composite adsorbents adding with nanoparticles

Thermal conductivity is one of key parameters of adsorbents, which will affect the overall system performance of adsorption chiller. To improve adsorbent’s thermal conductivity is always one of research focuses in chemisorption field. A new chemical composite adsorbent is fabricated by adding carbon coated metal(Aluminum and Nickel) nanoparticles with three different addition amounts into the mixture of chloride salts and natural expanded graphite aiming to improve the thermal conductivity. The preparation processes and its thermal conductivity of this novel composite adsorbent are reported and summarized. Experimental results indicate that the nanoparticles are homogenously dispersed in the composite adsorbent by applying the reported preparation processes. The thermal conductivity of the composite adsorbent can averagely enlarge by 20% when the weight ratio of the added nanoparticles is 10 wt%. Moreover, carbon coated aluminum nanoparticles exhibit more effective enlargement in thermal conductivity than nickel nanoparticles. As for the composite adsorbent of CaCl2-NEG, there is a big reinforcement from 30% to 50% for Al@C nanoparticles, however only 10% in maximum caused by Ni@C nanoparticles. The proposed research provides a methodology to design and prepare thermal conductive chemical composite adsorbent.

Cu-doped photovoltaic glasses by ion exchange for sunlight down–shifting

Ion exchange process is a widely studied synthesis technique for the controlled modification of silicate glass composition and properties, being moreover an easy and cheap approach. Silicate glasses containing copper are known to exhibit a broad luminescent band peaked around 500 nm, ascribed to 3d10–3d94s1 electronic transition of Cu+ ions; this band turns out to be much promising for the realization of down–shifting systems, being excited in the UV and near–UV region. Luminescent Cu–doped silicate glass sheets suitable as down–shifters to be used for covering solar cells have been prepared by thermal ion exchange. Synthesis of the Cu–doped glasses has been done by dipping pure silicate sheets (commercially used as cover of photovoltaic panels) into a fused copper salt mixture at temperature of 400 °C, for duration between a few minutes and some hours; two different types of copper chloride salt mixtures were explored, with the aim at obtaining luminescent glasses able to improve the Si cell yield. Absorption and luminescence glass features were collected and compared. The performance of the different samples was tested by a solar simulator, measuring the output power of a Si solar cell covered with the Cu–doped glass slides.

Differential response of two almond rootstocks to chloride salt mixtures in the growing medium

It was examined how essential cations, Ca2+ and K+, can mitigate the toxic effects of NaCl on two different almond species (Prunus amygdalus Batsch) rootstocks, Garnem (GN15) and Bitter Almond. The tree growth parameters (water potential (Ψw), gas exchange, nutrient uptake) and leaf chlorophyll (Chl) content were measured in control and NaCl-treated plants with or without KCl or CaCl2 supplements. The addition of CaCl2 and KCl to Bitter Almond trees reduced their dry weight, shoot growth and leaf number although net photosynthetic assimilation rate (A) was not affected. These results indicated that changing of photo-assimilates flux to proline and/or soluble sugars synthesis may help to increase leaf Ψw. The Garnem trees also did not respond to the CaCl2 and KCl addition indicating that the plants are already getting enough of these two cations (Ca2+ and K+). In both rootstocks, NaCl in the medium reduced growth attributes, Ψw, A, stomatal conductance (g s), and leaf Chl content. When CaCl2 and KCl fertilizers were added together with NaCl to Bitter Almond trees, leaf K+ and Ca2+ contents increased while Na+ and Cl– decreased leading to higher Ca/Na and K/Na ratios, but shoot growth was not improved and even declined compared to NaCl-treated trees. It appears that the addition of salts further aggravated osmotic stress as indicated by the accumulation of proline and soluble sugars in leaf tissues. The addition of KCl or CaCl2 to NaCl-treated GN15 trees did not increase A, leaf Ψw, and shoot growth but improved ionic balances as indicated by higher Ca/Na and K/Na ratios. The reduction in A was mainly due to non-stomatal limitations in GN15, possibly due to the degradation of Chl a, unlike Bitter Almond, for which the reduction of A was due to stomata closure. The improvement in ionic balances and water status of Bitter Almond trees in response to addition of KCl or CaCl2 was apparently offset by a high sensitivity to Cl–; therefore, no-chloride salts should be the preferred forms of fertilizers for this rootstock. Both rootstocks were sensitive to soil salinity and cation supplements were of limited value in mitigating the effect of excessive salt concentrations.

Differential Response of Two Almond Rootstocks to Chloride Salt Mixtures in the Growing Medium

Differential Response of Two Almond Rootstocks to Chloride Salt Mixtures in the Growing Medium

Design and thermal properties of a novel ternary chloride eutectics for high-temperature solar energy storage

A new ternary chloride salt mixture, named SYSU-4, was developed composed of NaCl, CaCl2 and MgCl2 to meet the needs of solar energy storage over 550°C. The eutectic point and composition of SYSU-4 was predicted from the calculated phase diagram and also validated by differential scanning calorimetry (DSC). SYSU-4 was prepared experimentally by static melting method and its thermo-physical properties including heat capacity, density and viscosity at high temperature were measured, which were determined by DSC, Archimedes and vibration–rotation methods, respectively. According to the calculated ternary phase diagram, the lowest eutectic temperature was 424.05°C, in good agreement with experimental results of 424°C measured by DSC. Heat capacity of SYSU-C4 was averaged as 0.83 and 1.19J/gK for solid and liquid phase, respectively referred to sapphire standard material. Density of SYSU-C4 decreased linearly from 2.5g/cm3 to 1.9g/cm3 with the increase of temperature from 500 to 750°C. Viscosity of SYSU-C4 also decreased from 4.0cp to 3.0cp as the temperature increased. Negligible changes on the melting and freezing points of SYSU-C4 in 50 thermal cycles at 370–550°C indicates excellent thermal cycling stability. Moreover, the thermal stability of SYSU-C4 was excellent under 700°C. The developed ternary chloride salt mixture SYSU-4 can be a promising eutectic mixture for high-temperature solar thermal energy storage.

Liquidus temperature and chemical durability of selected glasses to immobilize rare earth oxides waste

Pyroprocessing is are processing method for managing and reusing used nuclear fuel (UNF) by dissolving it in an electrorefiner with a molten alkali or alkaline earth chloride salt mixture while avoiding wet reprocessing. Pyroprocessing UNF with a LiCl–KCl eutectic salt releases the fission products from the fuel and generates a variety of metallic and salt-based species, including rare earth (RE) chlorides. If the RE-chlorides are converted to oxides, borosilicate glass is a prime candidate for their immobilization because of its durability and ability to dissolve almost any RE waste component into the glass matrix at high loadings. Crystallization that occurs in waste glasses as the waste loading increases may complicate glass processing and affect the product quality. This work compares three types of borosilicate glasses in terms of liquidus temperature (TL): the International Simple Glass designed by the International Working Group, sodium borosilicate glass developed by Korea Hydro and Nuclear Power, and the lanthanide aluminoborosilicate (LABS) glass established in the United States. The LABS glass allows the highest waste loadings (over 50 mass% RE2O3) while possessing an acceptable chemical durability.