Eutectic Research Articles

Melting experiments on Fe-S-O-C alloys at Martian core conditions: Possible structures in the O- and C-bearing core of Mars

Recent seismological studies of the Martian core revealed its relatively low density, suggesting the presence of large amounts of light elements including oxygen and carbon in addition to sulfur. In order to reveal crystallizing solids in the light-element-rich core of Mars, we performed high-pressure melting experiments on Fe-S-O-C alloys at 26–49 GPa using a laser-heated diamond-anvil cell. The liquidus phase relations in the Fe-S-O-C system were determined based on textural and chemical characterizations of recovered samples. The results show that Fe-S-O-C liquids crystallize FeO or Fe3C in the presence of small amounts of O or C in liquids. Accordingly the liquidus fields of Fe3S and Fe2S are small, and the quaternary eutectic point is found to be close to the Fe-Fe3S binary eutectic point. Under Martian core conditions, S-rich liquids have low liquidus temperatures to crystallize FeO or Fe3C compared to S-poor liquids. The pressure dependence of liquidus temperatures suggests that crystallization of Mars’ core starts at the center upon cooling. According to the FeO-Fe3C cotectic surfaces and their liquidus temperatures, an FeO and/or Fe3C inner core is predicted unless the Martian core remains entirely liquid.

Designing biodegradable aqueous biphasic systems for the selective separation of enzymes

In this work, the salting-out strength of reline eutectic mixture in aqueous solution of the non-ionic surfactant Triton X-102 has been demonstrated at temperatures between 298.15 and 323.15 K as a preliminary step to be employed in downstream operations of a biotechnological process. The phase diagrams data of reline-based Aqueous Two Phase Systems (ATPS) have been correlated using empirical models based on exponential and polynomial equations. The tie-lines have been empirically ascertained through physical properties characterization and Othmer-Tobias equation was proposed to correlate those data. After having studied the effect of the proposed reline eutectic mixture on two model enzymes (protease and lipase), the performance of this ATPS for selectively separating them was evaluated for three different feed compositions on the same tie-line, demonstrating their pertinence to segregate the lipase to one of the phases (yield about 95 %) and the protease to the other phase (yield about 98 %). These promising results are interesting for application in biotechnological reactions where proteases have been proved to be deleterious for lipases activity, as the biocompatibility of the proposed platform does not involve drastic negative effects on any of the enzymes.

Design of eutectic high-entropy alloys in the Co-Cr-Ni-V-Ti-Al system using Scheil solidification path optimization

The design strategy for eutectic high-entropy alloys (EHEA) is still in need of further exploration. This paper explores a new design approach using data computation, combining the simple mixing enthalpy method with a computed phase diagram approach based on a high-entropy alloy database. By calculating the thermodynamic empirical parameters of existing FCC/BCC-type eutectic alloy systems, the proportion range of alloy elements for eutectic design was narrowed. Ultimately, by analyzing the solidification path through the Scheil model, six eutectic compositions were obtained for the Co-Cr-Ni-Ti-V-Al alloy system that satisfy theoretical concepts. Microscopic characterization revealed that the actual alloy’s microstructure has only minor differences from the theoretically calculated results, with the main phase compositions of the alloys being FCC and BCC phases, aside from minor metal precipitates and third phases. However, significant differences were observed in the microstructures and mechanical properties of the six alloys. The research results demonstrate that this new design theory shortens the EHEA design cycle, enhances design accuracy and provides guidance for the eutectic design of target alloy systems.

A novel deep eutectic solvent-methyl isobutyl ketone biphasic system for the catalytic conversion of wheat straw to furfural and recovery of cellulose and lignin

Currently, the conversion of lignocellulosic biomass into furfural using deep eutectic solvents (DES) as the solvent and catalyst has many shortcomings including low furfural yields and inefficient resource utilization. To address these issues, a novel effective DES-methyl isobutyl ketone (DES-MIBK) reaction system was designed and used to catalyze the transformation of wheat straw to furfural and separate/recover cellulose and lignin in this work. The results showed that the DES-MIBK system could significantly improve furfural yield of up to 76.2 % at a mild condition (at 100 °C for 60 min). Furthermore, cellulose and lignin were fractionated and recovered from the reaction residues and the lignin yield reached 68.7 %. Moreover, the recovered cellulose exhibits high crystallinity (CrI=67.7 %). and the obtained lignin also has good uniformity with a small polydispersity index (PDI=2.36), and the results of FT-IR and 2D NMR indicated that the obtained lignin retains its fundamental structure. This research highlights that the innovative DES-MIBK system has a high-efficient in the production of furfural and the recovery of lignin and cellulose, which could provide a novel strategy for the high-value and sustainable application of lignocellulose biomass.

Layered laser-engraved wood-based composite capable of photothermal conversion and energy storage for indoor thermal management in buildings

Wood is used more and more in building. Phase change materials (PCM) with automatic temperature regulation and heat storage function have been widely concerned in the field of building energy conservation. However, phase-change materials have poor light induction and cannot absorb sunlight during the day in time, resulting in limited heat storage effect. For the purpose of achieving efficient energy collection and utilization, a laser-engraved method was employed in this study to directly generate a three-dimensional grid structure on the surface of wood. Then, the eutectic mixture of capric acid (CA) and stearic acid (SA) and nano-SiO2 composite PCM (CPCM) was impregnated into the supporting substrate with photothermal conversion capability. The obtained laser-engraved wood (LEW) loaded with CA-SA/Nano-SiO2 showed a latent heat of 64.706 J/g, a thermal conductivity of 0.732 W/(m⋅K) and a photothermal conversion efficiency of 64.46 %. Additionally, the three-dimensional porous structure of wood and the addition of nano-silica set up a double barrier for the leakage of PCM. Therefore, CPCM have prospective applications as indoor thermal insulation materials. In this research, a simple laser engraving method was adopted to endow the wooden substrate with photothermal conversion ability, which provides an idea to expand the application of photothermal conversion materials in the field of phase-change energy storage. In addition, the building simulation software validated the potential of CPCM in stabilizing indoor temperatures and reducing building energy consumption.

Advancing tent thermoregulation: Integrating shape-stabilized PCM into fabric design

Shape-stabilized phase change materials (ss-PCM) were prepared by impregnating capric acid (CA) and palmitic acid (PA) eutectic mixtures into the pores of Expanded Perlite (EP) using vacuum impregnation method. The ss-PCM was coated on fabric's surface using polyurethane (PU) solution, with different PCM/PU ratio. The microstructure, chemical stability, thermal properties and thermal reliability of ss-PCM were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT–IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Hydrophobicity performance was assessed by water contact angle (WCA). SEM images confirmed that CA–PA was successfully impregnated into the pores of EP. The results indicate that the latent heat of melting and freezing of the ss-PCM was 86.57 and 86.19 kJ/kg. The impregnated textile with the ss-PCM showed that the freezing enthalpies increased from 8.93 for Textile/PCM@5 up to 44.09 kJ/kg, for Textile/PCM@25 %. While Thermogravimetric analysis shows a good thermal stability of the composite textile/PCM. Mechanical properties revealed that the composite Textile/PCM@20 % present the higher tensile strength of 4.96 MPa compared to the other composite materials Furthermore, thermal cycling tests proved that the composite Textile/PCM@20 exhibits good long-term stability despite that both melting and freezing enthalpies were reduced by 7.4 and 14 %, respectively, after 100 cycles. These findings hold significant promise for applications in maintaining structures such as tents and buildings in thermal comfort range.

CsCl enrichment during solidification of molten LiCl–KCl–CsCl salt mixture

Metallic alloy fuels from fast reactors will be reprocessed by a non-aqueous electrochemical technique known as electrorefining. Electrorefining of spent metal fuel results in the accumulation of heat generating fission products especially 137Cs in the electrolyte, which is a eutectic salt mixture of 44 wt% LiCl and 56 wt% KCl. The fission products need to be removed from the salt so as to reduce the decay heat load and contamination thereby facilitating reuse of the salt and minimizing waste generation. Melt crystallization technique is a simple separation process being pursued for separation of fission products. This is a single step process which utilizes the difference in solubility of fission products in the solid and liquid phase. Crystallization involves purification of a substance from a liquid mixture by solidification of the desired component. Numerical modeling of separation of CsCl from a LiCl–KCl eutectic mixture by solidification was carried out using ANSYS Fluent (19.2). The enrichment of CsCl during solidification, its distribution in molten salt and segregation time were evaluated. Further, solidification experiments were conducted using the molten salt mixture and the predicted numerical results were validated.

Fabrication and performance characterization of Sb2Se3-GaSe eutectic systems

Sb2Se3-GaSe eutectic composites were synthesized by the vertical Bridgman method. XRD analysis and structural study of the Sb2Se3-GaSe eutectics showed that Sb2Se3 inclusions were uniformly distributed in the GaSe matrice. Three eutectic points in the Sb2Se3-GaSe system were studied. The compositions of the three eutectics of 80, 55 and 40 wt.% Sb2Se3 formed in the Sb2Se3-GaSe systems, and the corresponding melting points of 776, 725 and 698 K were determined. Anisotropy of the electrical properties of the eutectic systems was observed. The anisotropy degree was ~103 depending on the crystallization direction.

Advanced thermal energy storage made of a ternary CPCM with two phase change temperatures in building walls

This paper introduces a ternary composite phase change material (CPCM) comprising three phase change materials, with a eutectic mixture as the low phase change temperature (PCT) component. The thermal performance and stability of the CPCM are rigorously evaluated through simulations and experiments including step cooling curves, differential scanning calorimetry (DSC), thermal cycling, and Fourier-transform infrared (FTIR) spectroscopy. The ternary CPCM CA/C18-TD (2.0:8.0) exhibits superior latent heat storage—224.53 J/g compared to 143.83 J/g for the binary CA-TD (3.0:7.0)—and maintains stability without supercooling after 300 thermal cycles. It also proves cost-effective compared to its components. In building applications, walls integrated with the CPCM CA/C18-TD (2.0:8.0) exhibited significantly enhanced thermal regulation properties, including longer thermal delay times and reduced attenuation factors across both winter and summer conditions. Specifically, the CPCM wall reduced temperature fluctuations by up to 31.91 % in comparison to ordinary wall and 21.63 % against single PCM wall in winter, 54.51 % and 44.22 % lower than the ordinary and single PCM walls respectively in summer. These walls also showed a remarkable reduction in heat flow density by up to 17.49 W/m2 and 5.41 W/m2 compared to ordinary wall under summer and winter conditions, respectively. This means that the CPCM has superior insulation performance and reduces susceptibility to external environmental changes. These findings confirm CA/C18-TD (2.0:8.0) as an optimal CPCM for seasonal thermal energy storage in energy-efficient PCM wall.

Alkali rare earth double phosphates: Promising new high temperature scintillators

Alkali rare earth double phosphates were investigated for their X-ray induced scintillation. Double phosphates with stoichiometry A3Ln(PO4)2 (A = K or Rb, Ln = Eu or Tb) were synthesized via a eutectic molten salt flux yielding high quality single crystals. The systematic variation of the alkali and rare earth elements in the structure allowed for insights into the effects of the chemical composition on the scintillation output. The radioluminescence of these compositions under X-ray excitation is reported with a discussion of the variance of their luminosity as a function of both the constituent alkali and lanthanide elements. The relative luminosity of Rb3Tb(PO4)2 surpasses BGO by 30 %. The dependance of the scintillation on temperature is also investigated, including an unusual peak intensity increase for higher temperatures that can reach 1.4x of its value at room temperature for Rb3Tb(PO4)2 at 255 °C, and 2.1x for K3Tb(PO4)2 at 495 °C.

Molten salt synthesis of porous graphene-like carbons as peroxydisulfate catalyst for the efficient removal of rhodamine B dye.

Carbon materials have been receiving considerable attention as effective green catalysts for peroxydisulfate (PDS) activation to degrade organic pollutants. Herein, the porous graphene-like carbons (PGCs) were synthesized by pyrolyzing a nitrogen-rich biomass (peanut shell, PS) in the eutectic mixture of FeCl3 and ZnCl2. The results suggested that involvement of molten salts attributed the biochar the amazing properties such as high specific surface area (SBET = 2529.4 m2g-1), abundant structural defects, high nitrogen content (6.5%), and oxygen-containing functional groups on its surface. Especially when pyrolyzed at activation temperature of 800°C, mass ratio of 1:3:15 (PS:ZnCl2:FeCl3), and activation time of 2h, the optimized PGCs-op exhibited outstanding performance in the catalytic degradation of rhodamine B (RhB). Almost all of RhB (99.02%) was removed in 40min and basically not influenced by initial pH in the range of 3.00 to 9.98. Although the RhB degradation was influenced by anions (Cl-, HCO3-, HPO42-), the inhibition would be significantly alleviated within 120min unless these substances were high in concentration. Furthermore, the quenching tests revealed that the reactive species were involved in RhB degradation in the sequence of 1O2 > O2∙- > SO4∙- > ∙OH, among which singlet oxygen played a crucial role. Combined with characterization analysis, a possible mechanism of RhB degradation in PGCs-op/PDS system was proposed. Overall, this study provided a promising metal-free catalyst for the removal of organic pollutants while achieving reutilization of the waste biomass.

An Eutectic Mixture in the Tetrabutylammonium Bromide-Octanol System: Macroscopic and Microscopic Points of View.

An eutectic mixture of tetrabutylammonium bromide and octanol in the molar ratio 1-10 exhibited a melting point of -17 °C. This system was investigated by means of infrared spectroscopy, in the liquid and in the solid state. Classical molecular dynamics was performed to study the fine details of the hydrogen bond interactions established in the mixture. Both octanol and the mixtures displayed an almost featureless far-infrared spectrum in the liquid state but it becomes highly structured in the solid phase. DFT calculations suggest that new vibrational modes appearing in the mixture at low temperatures may be related to the population of the higher energy conformers of the alcohol. Mid-infrared spectroscopy measurements evidenced no shift of the CH stretching bands in the mixture compared to the starting materials, while the OH stretching are blue shifted by a few cm-1. Consistently, molecular dynamics provides a picture of the mixture in which part of the hydrogen bonds (HB) of pure octanol is replaced by weaker HB formed with the Br anion. Due to these interactions the ionic couple becomes more separated. In agreement with this model, the lengths of all HB are much larger than those observed in mixtures containing acids reported in previous studies.

Sodium Manganese Ferrite Water Splitting Cycle: Unravelling the Effect of Solid-Liquid Interfaces in Molten Alkali Carbonates.

In this work, the Na2CO3 of the sodium manganese ferrite thermochemical cycle was substituted by different eutectic or eutectoid alkali carbonate mixtures. Substituting Na2CO3 with the eutectoid (Li0.07Na0.93)2CO3 mixture resulted in faster hydrogen production after the first cycle, shifting the hydrogen production maximum toward shorter reaction times. Thermodynamic calculations and in situ optical microscopy attributed this fact to the partial melting of the eutectoid carbonate, which helps the diffusion of the ions. Unfortunately, all the mixtures exhibit a significant loss of reversibility in terms of hydrogen production upon cycling. Among them, the nonsubstituted Na mixture exhibits the highest reversibility in terms of hydrogen production followed by the 7%Li-Na mixture, while the 50%Li-Na and Li-K-Na mixtures do not produce any hydrogen after the first cycle. The loss of reversibility is attributed to both the formation of undesired phases and sintering, the latter being more pronounced in the eutectic and eutectoid alkali carbonate mixtures, where the melting of the carbonate is predicted by thermodynamics.

Development and thermal property analysis of biobased binary composite heat storage materials

Natural aliphatic dibasic acids are a type of bio-based material that shows promising potential as green phase change thermal storage materials due to their favorable thermophysical properties. However, these materials have been found to have issues with subcooling, low thermal conductivity, and poor temperature matching. In this study, three aliphatic dibasic acids, namely adipic acid (AA), sebacic acid (SA), and azelaic acid (ZA), were selected for further investigation. Three biobased eutectic systems, AA-SA (melting point: 118.3 °C), ZA-SA (melting point: 96.2 °C), and AA-ZA (melting point: 98.4 °C), were then prepared based on the calculation of Schrader's equation and experimental screening. The eutectic systems were thoroughly characterized, revealing thermal conductivities ranging from 0.4 to 0.5 W·m−1·K−1, with all systems exhibiting a subcooling of around 20 °C. Based on the principle of optimal overall performance, the AA-SA system was selected for modification. By incorporating Expanded graphite (EG) as a highly thermally conductive additive and nucleating agent, the AA-SA/EG composite phase change material (CPCM) was successfully prepared. This modification effectively reduced the supercooling degree of the bio-based phase change materials (PCM) and significantly improved its thermal conductivity by a factor of four. The resulting AA-SA/EG CPCM demonstrated excellent temperature suitability and has the potential to contribute to the application of bio-based phase change materials in waste heat recovery and solar energy systems. This study provides valuable insights into the development and optimization of bio-based phase change materials, contributing to the sustainable utilization of renewable resources for thermal energy storage applications.

Hydrophobic Deep Eutectic Solvents for Ethanol, Propan-1-ol, and Propan-2-ol Recovery from Aqueous Solutions

Separating hydroalcoholic mixtures remains a significant challenge in engineering. Liquid–liquid extraction has emerged as an appealing alternative method, because it avoids the need for the large energy inputs, volatile organic compounds, and high pressures that are typically required by other separation processes. This study explores the use of hydrophobic deep eutectic solvents (HDESs) composed of terpenes and 10-undecenoic acid as extraction agents for the liquid–liquid separation of hydroalcoholic mixtures composed of alcohols (ethanol, propan-1-ol, and propan-2-ol) and water. The water content in the solvents studied was notably low, reflecting their hydrophobic nature. For the dried HDES samples, the water content ranged from 553 to 4901 ppm. In contrast, the water-saturated samples exhibited higher water contents, ranging from 7250 to 20,864 ppm. The HDES based on thymol, DL-menthol, and L-menthol displayed a eutectic point at an xterpenes of approximately 0.67. These mixtures maintained a liquid state up to a mole fraction of terpenes around 0.75. In contrast, the HDES composed of carvacrol, fenchyl alcohol, and α-terpineol exhibited their eutectic point at an xterpenes near 0.5. Notably, these mixtures remained in a liquid state across the entire composition range studied. The 2:1 molar ratio (HBA:HBD) presented the best values for extracting alcohols, reaching 34.04%, 36.59%, and 39.78% for ethanol, propan-2-ol, and propan-1-ol, respectively. These results show that HDES can be applied to overcome issues with existing extraction solvents, increasing the separation efficiency and making the process eco-friendly.

Rubber oily liquids as transdermal and periodontal pocket drug delivery systems

This study investigates the incorporation of block natural rubber (NR) as a viscosity-inducing agent in NR oily liquids designed for drug delivery systems. A variety of liquids, encompassing natural oils, synthetic and non-oil liquids, and a eutectic mixture, were incorporated with NR using solvent displacement technique. Successful formulations were achieved for several oily liquids, with viscosity correlating to NR concentration. Particularly, a eutectic mixture of menthol and camphor exhibited optimal viscosity by direct dissolving enabling the development of transdermal ibuprofen delivery and injectable azithromycin for periodontitis treatment. NR prolonged the release of both drugs. The extended-release ibuprofen system holds promise for transdermal applications, while the azithromycin system displayed inhibitory effects against Staphylococcus aureus, Streptococcus mutans, and Porphyromonas gingivalis, suggesting potential for periodontitis treatment. Overall, this investigation advances the development of NR oily liquids as a versatile drug delivery system that can be applied both on the skin and for the local injection into the periodontal pocket, showcasing promise for various therapeutic applications.

Study of phase equilibria in a two-component system diphenyloxide <i>- n -</i> nonadecane

Using the Schroeder, UNIFAC and UNIFAC Dortmund methods, the fusibility diagram of the diphenyloxide – n –nonadecane system was calculated and it was shown that it belongs to the eutectic type. Individual substances and their mixtures were studied experimentally using a differential scanning microcalorimeter. On the DTA heating curve of the eutectic alloy, two endo-effects are noted, corresponding to the polymorphic transition of n–nonadecane and the melting of the eutectic. A comparison of the eutectic coordinates calculated by these methods with experimental data is presented. For a eutectic alloy, the specific enthalpy of fusion, molar values of entropy and enthalpy of fusion, volumetric specific enthalpy of fusion and density for standard conditions are calculated. The eutectic mixture can be recommended for use as a coolant, as well as the working fluid of a heat accumulator.

Enabling Gradient-Structured Solid Electrolyte Interphase by a Hydrated Eutectic Electrolyte for High-Performance Zn Metal Batteries.

Aqueous Zn metal batteries are attracting tremendous interest as promising energy storage systems due to their intrinsic safety and cost-effectiveness. Nevertheless, the reversibility of Zn metal anodes (ZMAs) is hindered by water-induced parasitic reactions and dendrite growth. Herein, a novel hydrated eutectic electrolyte (HEE) consisting of Zn(BF4)2·xH2O and sulfolane (SL) is developed to prevent the side reactions and achieve the outstanding cyclability of ZMAs. The strong coordination between Zn2+ and SL triggers the eutectic feature, enabling the low-temperature availability of HEEs. The restriction of BF4 - hydrolysis in the eutectic system can realize favorable compatibility between Zn(BF4)2-based electrolyte and ZMAs. Besides, the newly-established solvation structure with the participation of SL, H2O, and BF4 -, can induce in situ formation of desirable SEI with gradient structure consisting of B,O-rich species, ZnS, and ZnF2, to offer satisfactory protection toward ZMAs. Consequently, the HEE allows the Zn||Zn symmetric cell to cycle over 1650h at 2mAcm-2 and 1mAhcm-2. Moreover, the Zn||NH4V4O10 full batteries can deliver a prolonged lifespan for 1000 cycles with a high capacity retention of 83.4%. This work represents a feasible approach toward the elaborate design of advanced electrolyte systems for next-generation batteries.

Assessing boronized and aluminized thermal diffusion coatings in molten chloride salt and molten sodium environments

The service of structural materials, such as steels and alloys, in molten salt and sodium-cooled reactors in nuclear power generation is associated with high temperature corrosion of these materials, which leads to degradation and failures of structural components. To prevent these issues and to extend the reactor components' service life, protective coatings on steels need to be employed. In the present work, thermal diffusion protective coatings based on borides and aluminides have been tested, for the first time, in molten Na-K-Mg-chlorides of eutectic composition and in molten sodium at 500 °C in high-purity Ar glovebox where the test conditions simulated molten materials environments in nuclear reactors. The structural and compositional examination of the proposed protective coatings revealed only their minimal changing and deterioration in the corrosive environments. Thus, no or minimal formation of the corrosive scale on the top of the coatings was observed with neither structure transformation, nor reduction of the protective layer after 30-days testing in the molten materials' environments. Furthermore, no penetration of the corrosive media to the steel substrates occurred. Due to promising test results, the selected protective coatings may be highly recommended for further long-term and higher temperature testing in modeling and actual molten salts and molten sodium conditions associated with the service in nuclear reactors.

Influence of Hydrogen Bond Acceptors and Water Content on Surface Tension in Glycol-Based Eutectic Mixtures

Influence of Hydrogen Bond Acceptors and Water Content on Surface Tension in Glycol-Based Eutectic Mixtures