Eutectic Research Articles

Nanoencapsulation of phase change material with CuO nanoparticles: Development of thermal properties for energy storage

Today, the efficient use of energy resources has become essential due to the increasing need for energy. Therefore, thermal energy storage systems are used to minimize lost energy and more efficient energy consumption can be achieved by preventing energy losses. Phase change materials (PCMs) can be effectively used in thermal energy storage and are among the promising materials for a carbon–neutral future. In this study, the synthesis of nanoencapsulated phase change material (NEPCM) containing CuO NPs for use in thermal energy storage systems is included. In the production of phase change material, Copper oxide Nanoparticles were added into urea–formaldehyde resin as shell material, and an NEPCM, a eutectic mixture of capric acid-myristic acid, was prepared. Since the final product will be used in the structure, the phase change material was optimized for room temperature. In-situ polymerization, the synthesis process was carried out to obtain a better shell material to improve thermal properties and prevent leakage. Scanning Electron Microscopy and Fourier-transform infrared spectroscopy analysis were used to determine the morphology and chemical structure of the prepared NEPCM. Elemental analysis was performed to determine the presence of CuO NPs as shell material in urea–formaldehyde resin. Differential scanning calorimetry analyses were performed to determine the thermophysical properties. While the thermal degradation for CuO NPs-NEPCM occurred between 22.78–29.45 °C, the thermal degradation temperature shifted and the thermal degradation status in the first stage was less than that of normal NEPCM. It was observed that the thermal stability and strength of NEPCM increased with the addition of CuO NPs. NEPCM containing CuO NPs has thermal energy storage and energy conservation potential in buildings as a heat storage material. This study can provide an effective way to synthesize form-stable CuO-doped NEPCMs that are economically feasible for thermal applications and have the potential to contribute to future energy storage requirements.

Eutectic molten salt assisted fabrication of microporous biochar for greenhouse gases adsorption

The utilization of eutectic molten salt technology has emerged as a prominent area of investigation aimed at fabricating a novel carbon material sorbent based on biomass wastes. The adsorption mechanism on CO2 adsorption remains inadequately elucidated as well. Herein, the biochar fabrication process involving eutectic molten salt method at intermediate-low temperature of 550 °C was successfully achieved and investigated in detail. The impacts of molten salt composition, monomer salt’s anion and cation, and pyrolysis parameters were firstly studied on the resulting microporous biochar of 1.8 nm pore diameter and 975 m2/g surface area. The optimized conditions are 550 °C, 15 °C min−1 ramp rate, 120 min holding time, Na+ cation, NO3– anion, and ternary salt KCl/NaNO3/Na2SO4 of 32.5/30.4/37.1. The efficient adsorbent exhibited abundant micropores and a substantial specific surface area, leading to enhanced CO2 adsorption quantity of 3.75 mmol/g (the calculated capacity is up to 4.54 mmol/g) at pressure state of 1.6 MPa. Investigation into key factors, adsorption kinetics, and adsorption isotherm revealed that CO2 capture by optimal adsorbent predominantly stemmed from micropore filling, van der Waals forces, hydrogen bonds, and Lewis acid-base interactions. This research contributes novel insights into the utilization of biochar adsorbents for CO2 capture in the realm of industry.

Biphasic Production of 5-hydroxymethylfurfural (HMF) in a Recyclable Deep Eutectic Solvent-based System Catalyzed by H4SiW12O40.

The reaction with in situ extraction to yield 5-hydroxymethylfurfural (HMF) from Fru was investigated using a biphasic system based on a self-consuming deep eutectic solvent (DES) as reaction phase. The significance of choline chloride (ChCl), a cost-effective and safe quaternary ammonium salt, was evident in enhancing 5-HMF yield through fructose dehydration and concurrently suppressing side reactions. The DES system demonstrated fast reactions with high selecivities and recyclability across five cycles. The observed decline in H4SiW12O40 activity, primarily due to proton leaching, was successfully restored with the addition of HCl. Furthermore, ChCl exhibited ease of recrystallization in the presence of acetonitrile. This research proposes an environmentally friendly approach for 5-HMF production through a reusable-biphasic process. The presented reaction system suppresses completely the formation of levulinic and formic acid leading to HMF yields of up to 84% of selectivities of up to 88% after 30 minutes at 80 °C. The system was recycled over 16 runs and after an initial slight loss of activity the system in the run 0-5, run 6-15 has shown a constant HMF output as in the first recycling run.

Chemistry and relevant thermophysical properties of Pb84.3Li15.7 liquid solutions: Updated view and identification of new and coherent values

The liquid breeding blanket concept of a fusion reactor is based on the employment of the eutectic Lead-Lithium solution (LLE), where Lithium, enriched in 6Li, has the purpose of regenerating Tritium by reacting with neutrons, while Lead enhances the process acting as neutrons multiplier. Anyway, despite the huge interest on this binary system, LLE is not characterized yet by a fully consolidated description of its basic thermophysical properties and, in many cases, the spread of values reported so far in literature remains still significant. The purpose of this paper is hence to check again the many data available in literature, with a special attention to the ones more recently published, trying to explain and solve their inhomogeneity. Taking into account the general features of the Pb-Li interaction and particularly the not ideal behaviour of the Pb-Li liquid solutions, the following thermophysical properties of the LLE are dealt in detail: specific heat; density and volumetric thermal expansion coefficient; thermal conductivity and diffusivity; electrical resistivity; Sieverts' constant of Hydrogen. Based on the deep analysis of all the reported experimentation and through the adoption of several comparison criteria, the most trustable correlation is sought for each of the above properties; additionally, when a robust correlation couldn't be retrieved, a new, optimized, one has been proposed, capable also to foresee correctly the effect of small composition variations and to assure the internal coherence among linked properties.Specific heat and density values resulted at the end accurately described and not needing for additional experimentation; thermal properties and electrical resistivity can be evaluated with decent confidence, even if their uncertainty could be somehow reduced by future investigations; for Sieverts' constant it has not possible yet to identify a unique, trustable correlation, anyway the range of values correctly assumed up to 900K has been significantly restricted.

Properties of foam concrete containing phase change material impregnated pumice

Energy consumption rises as a result of numerous electrical devices used to maintain thermal comfort of interior building areas. Using building materials with low thermal conductivity and density as well as an effective thermal energy storage plan can help to mitigate this. In order to enhance thermal performance of building, phase change material (PCM) was incorporated to foam concrete mixture in this study. Capric acid (CA)-palmitic acid (PA) eutectic mixture was prepared and impregnated with pumice (50 % by weight), a light and porous material. DSC results indicated that pumice/CA-PA composite exhibited a melting temperature of 22.84˚C and a freezing temperature of 20.85˚C, with corresponding enthalpy values for melting and freezing determined to be 85.4 J/g and 85.1 J/g, respectively. TGA analyses demonstrated that operational temperature of pumice/CA-PA composite was significantly below its thermal degradation temperature (194˚C). The prepared pumice/CA-PA composites were replaced with silica aggregate at different rates and incorporated in foam concrete mixture. Porosity and water absorption values rose as pumice/PCM content increased, yet there was a 7.2–41.1 % drop in dry unit weight when compared to reference. Compressive strength also showed a linear decrease and the lowest compressive strength value was recorded as 4.71 MPa in the presence of 40 % pumice/PCM. Thermal conductivity dropped from 0.487 W/mK to 0.167 W/mK, suggesting that foam concrete samples that were produced are all suitable as insulation materials. In peak solar radiation hours, PCM-impregnated pumice foam concrete (PFC) provided about 11.8 % and 8.72 % surface and room center temperatures compared to that of the reference in maximum case. PFC with PCM provided 6.54 % warmer surface temperature in cold weather. PFC-PCM can provide a cooler indoor temperature during peak temperature hours. Therefore, it may have a great potential to decrease the cooling load of a building.

Effects of different molecular weight polyethylene glycols on the thermophysical properties of caprylic acid and 1-dodecanol eutectic mixture

Cold-chain logistics involve a wide range of temperature-control issues and efforts are being made to improve the efficiency of energy-storage systems. In particular, thermal-energy storage technologies, including sensible, thermochemical, and latent heat storage, have been extensively researched to enhance system efficiency and mitigate peak energy demand. This study investigated the effect of the polymer molecular weight on the heat-storage capacity of eutectic materials. The thermophysical properties and thermal stabilities of caprylic acid (Ca) and 1-dodecanol (Do) eutectic mixtures were examined in conjunction with ethylene glycol (EG) and polyethylene glycol (PEG) with different molecular weights (MWs). The dissolution behavior, heat-storage capacity, latent heat, temperature-retention time, and heat conductivity were strongly influenced by molecular weight, which was attributed to the self-aggregation and dispersion of EG and PEG within the Ca-Do eutectic mixture. PEG-4K and 35K exhibited good dissolution in the Ca-Do eutectic mixture, resulting in increased heat-storage capacity, latent heat, thermal conductivity, and thermal stability. By using PEGs with higher MWs, the temperature-retention durations in the 2–8 °C range were enhanced. Conversely, PEG with an ultrahigh MW of 1000K exhibited flocculation and phase separation within the Ca-Do eutectic mixture owing to exceptionally high self-aggregation. The thermophysical properties of the Ca-Do eutectic mixture were influenced by the variations in the MWs of EG and PEGs, as well as their dispersion within it. Considering the efficacy and commercial availability of PEGs, Ca-Do-35K is a promising candidate for thermal-energy storage applications in the range of 2–8 °C.

Theoretical study of solidification phase change heat and mass transfer with thermal resistance and convection subjected to a time-dependent boundary condition

The solidification of phase-change materials (PCMs) is a key process that occurs commonly in materials science and metallurgy, such as in the casting of alloys and energy management systems. There is a lot of literature in this area that assumes the PCMs are in close contact with the heat source or sink. However, a non-freezing wall frequently encloses them in practical situations. This work presents a phase change problem that describes the solidification of a semi-infinite PCM with thermal resistance. We assume that time-dependent heat flux drives the solidification process. The PCM first convert into mush and then into solid, which leads to a three-region problem. The current study accounts for both conduction as well as convection heat transfer mechanisms. Unfortunately, the exact solution to such problems with time-dependent flux-type boundary conditions may not be possible. Thus, there is considerable interest in deriving the analytical solution. The space–time transformation yields the analytical solution to the problem. A numerical example of Al−Cu alloy with 5%Cu is presented to demonstrate the current study. Thermal resistance shows a pronounced impact on the temperature field. Lower thermal resistance offers faster solidification rate. It is found that as the heat transfer constant increases, the rate of propagation of solid–mush and mush–solid interfaces gets enhanced. In addition, the growth of thermal resistance is of linear nature, with variation in the value of Q. The solidified region has higher concentration than the mush region. The current study is applicable to both eutectic systems and solid solution alloys.

Effect of Simultaneous Mg and Zn Addition on the Solidification and Microstructure of Multi-Element Hypoeutectic Al-Si Alloys

Effect of Simultaneous Mg and Zn Addition on the Solidification and Microstructure of Multi-Element Hypoeutectic Al-Si Alloys

Molten salt synthesis of Ti-Si-C coating on SiC particles and hot pressing of the prepared powders

SiC particles coated with Ti-Si-C layer were prepared by the molten salt synthesis method using NaCl-KCl eutectic mixture as the reaction medium and Ti metal powder as the Ti source. The synthesis was conducted under static argon atmosphere at 900 °C for 1–3 h. The post-synthesis treatment included dissolution of salts in hot water, followed by ultrasonic dispersion and sedimentation procedures. The thickness of the Ti-Si-C layer varied from 0.1 to 0.9 μm as the ratio of Ti to SiC components in the starting mixture changed from 0.05 to 0.4. The layer contained mainly nanocrystalline Ti5Si3, minor phases were TiC and Ti3SiC2. The as-prepared powders were hot pressed under 30 MPa at 1700 °C. The densification behavior of the samples during hot pressing as well as changes both in phase composition and in microstructure were studied. The flexural strength of the hot-pressed samples increased with an increase in the Ti:SiC molar ratio, giving the value as high as 213 ± 20 MPa for the sample with Ti/SiC = 0.4.

Solid-state synthesis of novel anticancer drug eutectic mixture; anticancer, physical and thermal studies

Green, solvent-free synthesis is adopted for a new pharmaceutical drug-drug eutectic with the utmost 100% yield. The synthesized eutectic mixture is significant for anticancer activity. The mandate of clinical tests could be avoided as selected nicotinamide, salicylamide, p-aminoacetinilide and benzanilide are known drugs. The compositional behaviors and established phase diagrams infer the formation of eutectics. The thermal behaviors of eutectics are studied using DSC. Further studies of eutectics are targeted for their biological applications, particularly for cell viability and anticancer activity against SiHa cancer cells where eutectic of benzanilide-salicylamide system infers its potential applicability for anticancer activity.

A novel process for producing Al-Si alloy utilizing aluminum-silicon oxide extracted from coal fly ash

As a kind of solid waste rich in aluminum and silicon resources, the comprehensive utilization of coal fly ash (CFA) will be of great significance to reduce environmental pollution and improve economic benefits. This work proposed a facile and environmentally friendly cleaning process for producing Al-Si alloy by molten salt electrolysis from CFA extract, aluminum-silicon oxide (ASO). The dissolution behavior and dissolution reaction mechanism of ASO were studied by high temperature visual dissolution experiment, thermodynamics analysis and phase analysis. Due to the chemical reaction between ASO and cryolite-based melt, ASO powder dissolves rapidly in melt and the dissolution rate of ASO is not determined by the phase compositions but by the mass ratio of Al2O3/SiO2. For replenishing the oxide concentration in the electrolyte as quick as possible, the proper mass ratio of Al2O3/SiO2 is in the range of 0.75–7.5. The electrochemical co-reduction behavior of Si (IV) and Al (III) ions on the W electrode was performed by cyclic voltammetry and square wave voltammetry. The results indicated that the reduction of Si (IV) ion in the melt was a two-step irreversible process. Hypoeutectic Al-Si alloy and eutectic Al-Si alloy were prepared by galvanostatic electrolysis using ASO as raw material. This innovative technology can realize high-value recycling of CFA resources and low carbon emission, low energy consumption production of Al-Si alloy.

Improvement of the strength of ternary eutectic V-Si-B alloys at ambient and high temperatures due to Cr additions

In the present study high-temperature compression tests on a chromium-alloyed ternary eutectic V-9Si-6.5B are reported. The ternary eutectic composition is located within the VSS (V solid-solution)-V3Si-V5SiB2 three-phase region of the respective V-rich corner of the phase diagram. The high-temperature compressive yield stresses were determined by the 0.5 % offset method and the plastic strain was obtained by subtracting the combined compliance of the testing machine and the specimen from the individually measured load-displacement curves. The microstructures in the as-cast and heat-treatment state (1400 °C / 100 hrs) were analyzed using SEM, EBSD and TEM observations. The effect of Cr on the ternary eutectic formation was studied. After compression testing, dislocation activities were observed in the VSS and V3Si phases, while the ternary intermetallic phases were dislocation-free. The high-temperature plasticity in the Cr-added ternary eutectic alloys V-9Si-6.5B+xCr is mainly governed the VSS phase which forms the major phase of the eutectic. Thus, Cr additions are found to contribute to solid-solution strengthening in the ternary eutectic alloys while strongly influencing the deformability by decreasing the temperature at which brittle failure occurs in the present compression experiments.

Physicochemical characterization and evaluation of polarity influence in eutectic systems applied to drug solubility

In the process of discovery and development of APIs (Active Pharmaceutical Ingredients), the rate of solubility or aqueous dissolution plays a very important role from the first evaluations of the candidates to the development of final marketable products. Since only the solubilized form of an active ingredient is capable of being transported and exerting its therapeutic effect across biological membranes, it is of utmost importance to control its solubility. However, the number of APIs under development with low water solubility has notoriously grown in recent years. Their pharmaceutical use will face problems such as insufficient bioavailability, late onset of action, and the need for large dosages.The present study aims to evaluate the behavior of ciprofloxacin and norfloxacin (fluoroquinolones), as model APIs for their different solubilities, in aqueous and non-aqueous natural deep eutectic solvents (NADES). The main objective is to improve the solubility of both drugs in pharmaceutical studies and analytical applications. In order to do so, two sets of eutectic solvents were selected, each composed with a polar solvent, an intermediate one, and a nonpolar solvent, as well. Very promising results were obtained in NADES of polar and intermediate polarity, for both drugs. In addition, the physicochemical characterization of such solvents was carried out to better understand the aforementioned results.

Influence of co-solvents on properties of terpene-based eutectic mixtures: Implications for skin delivery

Terpene-based eutectic mixtures (EMs) are attractive platforms for transdermal delivery due to their solubilizing potential and ability to alter the barrier function of the stratum corneum (SC). Despite this, little is known about the effect of diluting EMs with co-solvents (CSs) on their solubility- and permeation-enhancing properties. Furthermore, insufficient attention has been paid to comparing these platforms with traditional solvents, such as propylene glycol (PG) or ethanol (EtOH). To address this gap, the present study investigates the impact of the CS content in EM:CS blends on the transdermal delivery of clotrimazole (CLOT). Two CSs, PG and EtOH, and two terpene-based EMs, menthol:thymol and thymol:β-citronellol, were used. Each of the EMs was investigated at two different molar ratios between the terpenes, with one being their eutectic point, to explore its potential benefit for skin permeation. At each step, properties of the blends were compared with those of pure CSs. The EM:CS blends showed a better solubilizing potential for CLOT than EMs or CSs on their own. A higher content of CSs in the blends resulted in a higher skin permeation and retention of CLOT, and a lower degree of disarrangement of the SC structure. Furthermore, the blends of EMs at their EPs led to overall poorer permeation profiles, implying that the permeation rate is more affected by the properties of the individual terpenes than by the specific ratio at the eutectic point between them. In conclusion, addition of CSs to the EMs promotes permeation and retention of CLOT, while reducing the skin impairment caused by the terpenes.

Investigation on effect of different types of inoculants on the solidification of ductile cast iron using thermal analysis

PurposeProducing superior-quality ductile cast iron demands the use of various intricate inoculants. In addition to iron and silicon, these materials also include alloying elements like calcium, barium, cerium, bismuth and zirconium. These elements are effective in minimizing carbide solidification and enhancing the formation of eutectic cells, thereby resulting in improved cast iron quality.Design/methodology/approachThis article discusses the findings of an investigation on how various inoculants impact critical thermal analysis parameters such as undercooling, recalescence and their correlation with the nucleation of graphite nodules and shrinkage tendency.FindingsFor the study, five distinct inoculants with varying active components in their chemical composition were utilized. The particular formulation of the inoculant has a notable impact on the extent of undercooling during the solidifying process of ductile cast iron. Investigation indicates that incorporating inoculant reduces the temperature at which austenite dendrites form and raises the eutectic freezing temperature. Upon analyzing the microstructure, it is found that the inclusion of inoculation led to a rise in the nodule count from 103 to 272 nodules.Originality/valueAn increased graphite factor, which denotes the growth of graphite nodules during the subsequent stage of the eutectic reaction, supports the benefits of inoculation. Ce and Bi-inoculation have increased the growth of graphite nodules in the cast area during solidification compared to other inoculant formulations. This enhanced production helps in decreasing the size of macroporosity.

Study on separation and purification of titanium alloys (TC4-6Al-4V) by molten salt electrolysis

With the widespread expansion of titanium applications and its significant increase in usage, the issue of recycling titanium resources after consumption has emerged. Focusing on titanium alloys with high usage, such as TC4 (Ti-6Al-4V), this article proposes a titanium separation and recovery method based on molten salt electrolysis. This method thoroughly analyzes the characteristics of elements in TC4 and electrochemical principles, ensuring that vanadium in the TC4 alloy does not undergo electrochemical dissolution when the electrolysis potential is below 0.3 V vs Pt. Subsequently, through electrochemical analysis, it was discovered that the precipitation of aluminum ions is influenced by concentration. Therefore, by controlling the concentration of aluminum in the eutectic molten salt, such as increasing the electrolyte concentration and shortening the electrolysis time, the precipitation of aluminum can be effectively avoided. Under the experimental conditions mentioned above, vanadium elements deposit at the bottom of the crucible in the form of anode slime, while aluminum dissolves and remains in the electrolyte. Meanwhile, titanium ions in the cathode region undergo electron reduction and deposit in the cathode area in the form of titanium, thus achieving precise separation of alloy elements. Experimental verification shows that the purity of the obtained titanium reaches 99.17 atomic percent. Therefore, this molten salt electrolysis method, which combines the physical properties of alloy elements with electrochemical principles, not only provides a new perspective for the separation and recovery of titanium and other critical metals, but also offers new research directions for the recovery technology of other alloy elements.

Preparation and characterization of fatty acid ternary eutectic mixture/Nano-SiO2 composite phase change material for building applications

In order to prepare a composite phase change material (PCM) with suitable phase transition temperature, strong temperature control performance, good latent heat properties, and low cost for incorporation into concrete, the goal is to control temperature cracks, and endow the building structure with temperature regulation capabilities through phase change. In this study, capric acid (CA), myristic acid (MA) and stearic acid (SA) were used as PCMs. Firstly, based on theoretical calculations, a ternary eutectic mixture of CA-MA-SA with a mass ratio of 67.16:22.98:9.86 was successfully prepared. Subsequently, a new composite PCM was created using a melt blending technique, incorporating nano-SiO2 as a supporting material. The comprehensive characterization results from FT-IR, SEM, XRD, DSC and TG indicate that nano-SiO2 interacts with CA-MA-SA through its porous structure and capillary action, as well as surface tension, rather than through any chemical interaction, when 65% of CA-MA-SA is adsorbed in nano-silica, the melting temperature and latent heat of the composite PCM are 19.23 °C and 97.82 J/g, respectively. Without any leakage of molten CA-MA-SA. This material exhibits a favorable temperature for phase transition and possesses a high amount of latent heat, making it a promising candidate for use in construction projects. Additionally, the composite PCM shows remarkable thermal stability after 200 phase change cycles, which not only lowers building energy usage but also conserves energy, making it ideal for broad use in civil engineering.

Solubilities of Hydrogen, Nitrogen and Carbon Dioxide in the Eutectic Mixture of Diphenylmethane and Biphenyl

Solubilities of Hydrogen, Nitrogen and Carbon Dioxide in the Eutectic Mixture of Diphenylmethane and Biphenyl

Eutectic Mixtures of APIs: A way to Improve the Physiochemical Properties and Oral Bioavailability of the Drugs

AbstractEutectic mixtures (EMs) are consisted of two or more components with a specific composition and melting point, have received a lot of attention in pharmaceutical research due to their potential to improve the physicochemical properties and oral bioavailability of active pharmaceutical ingredients (APIs). This review summarizes the most recent research on eutectic combinations of APIs and their use in pharmaceutical formulations. First, the fundamental concepts and characteristics of EMs are reviewed, focusing on their distinct thermodynamic properties and possible advantages in drug delivery systems. The tactics used for forming and characterizing EMs are then described, including techniques such as thermal analysis, spectroscopy, and microscopy. The review delves into the diverse approaches utilized to enhanced the solubility, dissolution rate and oral absorption of poorly water‐soluble APIs through the formation of EMs, including the selection of suitable co‐formers, optimization of composition ratios, and formulation techniques. Furthermore, notable examples of EMs in pharmaceutical development are presented, showcasing their efficacy in enhancing the bioavailability of a wide range of drug compounds across different therapeutic classes. Overall, this review covers the potential of EMs as a promising approach to address formulation challenges and improve the therapeutic performance of APIs, paving the way for the development of more effective and patient‐friendly drug products.

A potential DES catalyst for the fast and green synthesis of benzochromenopyrimidines and pyranopyrimidines

A gentisic acid based-Deep Eutectic Solvent (MTPPBr/GA-DES) was synthesized by mixing one mole of methyl triphenylphosphonium bromide (MTPPBr) and one mole of gentisic acid (GA: 2,5-dihydroxy-benzoic acid) based on the eutectic point phase diagram. Then, it was characterized by FT-IR, NMR, densitometer, and TGA/DTA techniques and used as a potent and novel catalyst for the fast and green synthesis of: (i) Five new 2(a-e) and five known 2(f-j) benzo[6,7]chromeno[2,3-d]pyrimidines and (ii) One new (3a) and eleven known 3(b-l) pyrano[2,3-d]pyrimidines, in solvent-free conditions, short reaction times, and high yields. It is important to mention that for the synthesis of 2(a-j), there is only one reference which states that the reaction times are extremely long (720–2400 min), while these times are reduced to approximately 35–50 min in our proposed strategy, indicatinging that the rate of reactions will be 20–48 times faster, which is the clear and most obvious advantage of our approach.