Eutectic Research Articles

Structural characterization and physicochemical properties of different hydrophilic natural deep eutectic solvents.

To overcome the toxic nature of organic solvents, scientific interest in the use of green solvents, particularly natural deep eutectic solvents (NADES), has increased over the past decade, leading to new applications in the food, nutraceutical, pharmaceutical, and cosmetic industries. Understanding the physicochemical properties and molecular interactions of NADES is essential for uncovering new potential applications in these fields. In this study, several lactic and citric acid-based NADES, as well as chloride choline- and urea-based NADES, were evaluated for their physicochemical properties, including density, pH, viscosity, conductivity, and refractive index. Additionally, nuclear magnetic resonance (NMR), and in particular nuclear Overhauser enhancement spectroscopy (NOESY), was employed to investigate the intermolecular interactions between the NADES components to confirm the formation of the eutectic mixture. The extraction efficiency of the confirmed NADES was tested for extracting polyphenols as a proof of concept to highlight their relationship with the measured properties. Lactic and choline chloride-based NADES provided the highest extraction yields. These results were also compared with the predicted extraction capabilities of each NADES provided by the COSMO-RS software.

Ligand‐Free Zn Catalyzed Synthesis of Functionalized iIdoloacridines

Abstract: An efficient, ligand‐free, and Zn‐catalyzed dehydrogenation of acridinol/ cyclization of imine product/ dehydrogenative C(sp3)‐H functionalization utilizing ChCl‐based deep eutectic solvent system for the assembly of functionalized indoloacridines 9 is reported. The protocol features mild reaction conditions, VOCs free process, broad substrate scope, and applicable gram‐scale synthesis. Furthermore, absorption and solvatochromism properties were explored for the synthesized compounds.

Engineering pH and Temperature-Triggered Drug Release with Metal-Organic Frameworks and Fatty Acids

This study reports the successful synthesis of core-shell microparticles utilizing coaxial electrospray techniques, with zeolitic imidazolate framework-8 (ZIF-8) encapsulating rhodamine B (RhB) in the core and a phase change material (PCM) shell composed of a eutectic mixture of lauric acid (LA) and stearic acid (SA). ZIF-8 is well-recognized for its pH-responsive degradation and biocompatibility, making it an ideal candidate for targeted drug delivery. The LA-SA PCM mixture, with a melting point near physiological temperature (39 °C), enables temperature-triggered drug release, enhancing therapeutic precision. The structural properties of the microparticles were extensively characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Drug release studies revealed a dual-stimuli response, where the release of RhB was significantly influenced by both temperature and pH. Under mildly acidic conditions (pH 4.0) at 40 °C, a rapid and complete release of RhB was observed within 120 h, while at 37 °C, the release rate was notably slower. Specifically, the release at 40 °C was 79% higher than at 37 °C, confirming the temperature sensitivity of the system. Moreover, at physiological pH (7.4), minimal drug release occurred, demonstrating the system’s potential for minimizing premature drug release under neutral conditions. This dual-stimuli approach holds promise for improving therapeutic outcomes in cancer treatment by enabling precise control over drug release in response to both pH and localized hyperthermia, reducing off-target effects and improving patient compliance.

Designing an all-laser processing and operating microheater conceptual device for medical applications

Obstructive sleep apnea (OSA) is a prevalent condition affecting a significant portion of the population, with a reported prevalence of 33% and 19% in males and females, respectively. OSA is associated with an increased risk of sudden death, with studies suggesting nearly double the risk compared to individuals without OSA. The condition is characterized by frequent sleep disruptions due to airway collapse, often at the level of the tongue or soft palate. Current treatment approaches primarily rely on radiofrequency (RF) ablation for tissue volume reduction. While effective, this technique can cause significant collateral damage and postoperative pain due to extensive burning of surrounding tissues. To avoid such drawbacks, in this work it is proposed and discussed the features of a possible conceptual all-laser-processing and operating device that can produce localized heat affected zones, with the possibility to monitor the local temperature during the procedure. The device is based on the eutectic composition of the system Al2O3-YAG, with double doping Nd3+ and Cr3+ crystalline fiber tip, which is prepared by the Laser-Heated Pedestal Growth technique on a sapphire single crystal fiber end. The results showed that the tip, although highly Nd3+-doped, follows the Jackson-Hunt relation for binary eutectic compounds. The lifetime of the luminescence produced by the Cr3+ doping, emitted by the eutectic tip, can act as a temperature sensor for the device in the range of 30 to 100 °C.

One-Pot, Solvent Free Synthesis of 2,5-Furandicarboxylic Acid from Deep Eutectic Mixtures of Sugars as Mediated by Bifunctional Catalyst.

Currently one-pot conversion of sugars to 2,5-furandicarboxylic acid (FDCA) is of significant interest due to the attainability of sugars as a feedstock and the enormous potential of FDCA as a bioplastic monomer. However, it remains challenging to construct efficient catalysts for this process. In this study, Co3O4 species were anchored to a sulfonated covalent organic framework thus affording a bifunctional catalyst (Co3O4@COF-SO3H). The sulfonic acid sites dehydrate sugars to 5-hydroxymethylfurfural (HMF), which is next oxidized to FDCA as catalyzed by the Co3O4 species. Such a process was applied in the conversion of various binary and ternary deep eutectic mixtures involving choline chloride and sugars without additional solvent. The maximum FDCA yield of 84 % was obtained using glucose-fructose eutectic mixture as the substrates. Moreover, the catalyst was recyclable and stable under the applied reaction conditions. Our process eliminates the employment of organic solvents and expensive noble metal catalysts, resulting in green and economic biomass conversions.

Coexistence of Superconductivity and Magnetic Ordering in the In–Ag Alloy Under Nanoconfinement

The impact of the interface phenomena on the properties of nanostructured materials is the focus of modern physics. We studied the magnetic properties of the nanostructured In–Ag alloy confined within a porous glass. The alloy composition was close to the eutectic point in the indium-rich range of the phase diagram. Temperature dependences of DC magnetization evidenced two superconducting transitions at 4.05 and 3.38 K. The magnetization isotherms demonstrated the superposition of two hysteresis loops with low and high critical fields below the second transition, a single hysteresis between the transitions and ferromagnetism with weak remanence in the normal state of the alloy. The shape of the loop seen below the second transition, which closes at a low magnetic field, corresponded to the intermediate state of the type-I superconductor. It was ascribed to strongly linked indium segregates. The loop observed below the first transition is referred to as type-II superconductivity. The secondary and tertiary magnetization branches measured at decreasing and increasing fields were shifted relative to each other, revealing the proximity of superconducting and ferromagnetic phases at the nanometer scale. This phenomenon was observed for the first time in the alloy, whose components were not magnetic in bulk. The sign of the shift shows the dominant role of the stray fields of ferromagnetic regions. Ferromagnetism was suggested to emerge at the interface between the In and AgIn2 segregates.

Comprehensive impact of pre-treatment methods on white radish quality, water migration, and microstructure

The preprocessing stage is crucial in vegetable processing, significantly influencing the final product's quality. This study investigates the effects of various pre-pre-treatment methods, including cutting, blanching, osmotic, and ultrasound-assisted osmotic treatment, on the quality characteristics, water migration, and microstructure of white radish. The results showed that osmosis and ultrasound-assisted osmosis has the least effect on the total color difference (ΔE) and the greatest water loss (WL) (p < 0.05); blanching has the least effect on the hardness and eutectic points (p < 0.05); and the blanching-ultrasound-assisted osmosis has the greatest solid gain (p < 0.05). The increase of WL led to a decrease in hardness (−0.82). By analyzing the quality characteristics of different pre-treatment methods, contributing to the development of suitable pre-treatment methods for different products and optimization pre-treatments according to requirements. The mechanism of quality characteristics of pre-treatments on products is the future research direction.

Investigate of Electrochemical Properties of Nd(II) and Nd(III) in Eutectic LiCl-KCl Molten Salt

Pyroprocessing is one of the promising methods to reprocess the spent nuclear fuel. Neodymium (Nd) constitutes about one third of rare earth in fission products, however, the electrochemical properties of Nd have not been thoroughly understood, especially the exchange current. In the present study, the transit electrochemical methods of cyclic voltammetry and square wave voltammetry were applied to study the properties of Nd in LiCl-KCl system. The reduction of Nd3+ was determined as a two-step reaction with Nd3+/Nd2+ to be a reversible but Nd2+/Nd to be a quasi or irreversible reactions. Additionally, parameters such as the diffusion coefficient, exchange current, and apparent potential were derived from the cyclic voltammetry curves. Their relationship with temperature and concentration was investigated under 723 K, 773 K, 823 K with concentrations of 3 wt%, 6 wt% and 9 wt%. The present study contributes significantly to rich the database of Nd in LiCl-KCl molten salt and to understand the electrochemical behaviors of Nd during electrochemical separation of spent nuclear fuel.

Extraction of mucilage polysaccharides from chia seed by hydrophobic deep eutectic solvents-based three-phase partitioning system: A phase behavior-driven approach

By incorporating the hydrophobic deep eutectic solvents (DESs) into the three-phase partitioning (TPP) technique, a TPP-based method was developed to extract the chia seed polysaccharide (CSP) from chia seed. Through a single-factor experiment and response-surface model, the optimal condition for the TPP extraction was determined as DES composed of dodecanoic acid and octanoic acid in a 1:1 M ratio, (NH4)2SO4 concentration of 32.86 %, crude extract–DES ratio of 0.93 (v/v), aqueous phase pH of 4.38, extraction temperature of 35 °C, and extraction time of 10 min. The polysaccharide yield of the constructed TPP method is 8.65 %, which is higher than the conventional water extraction method (yield is 6.96 %). Molecular dynamics simulations reveal the phase behavior of proteins and polysaccharides in the TPP system, showing that noncovalent interactions play a crucial role in the TPP system. The CSP obtained by the TPP method exhibits distinctive composition, structural, physicochemical, and functional properties, leading to improved thermal stability, rheological behavior, and antioxidant performance. Compared with the traditional extraction method, efficient extraction of CSP can be achieved flexibly using the proposed TPP approach, resulting in high yield and quality of CSP, which provides a new path for the large-scale utilization of chia seed.

The preparation and properties of bamboo lignocellulosic nanofibers based on deep eutectic solvent system

The preparation and properties of bamboo lignocellulosic nanofibers based on deep eutectic solvent system

In-situ synthesis and microstructural evolution of a SiC reinforced Al-50Si composite exhibiting exceptional thermal properties

Incorporating carbon nanotubes (CNTs) into Al-Si alloy to prepare in-situ SiC/Al-Si composites enhances thermal conductivity (TC) and reduces the coefficient of thermal expansion (CTE). However, challenges include CNTs aggregation and uneven SiC distribution. This study uses fluidized bed chemical vapor deposition (FBCVD) to achieve uniform CNTs coverage on Al-50Si powder. Subsequent powder hot extrusion and heat treatment above the eutectic temperature enable a gradual reaction between CNTs and Al/Si atoms, resulting in uniformly dispersed SiC within the SiC/Al-50Si composite. The formation mechanism of in-situ SiC particles and their impact on the microstructure, thermal and mechanical properties of the composite are further investigated. The formation process involves a two-step chemical reaction: lamellar Al4C3 phases transform into lamellar eutectic SiC + Al phases, which then transition into polyhedral SiC particles through epitaxial growth. This in-situ formation of SiC particles also impedes Si growth during heat treatment, refining Si particles and enhancing the composite’s properties. The resulting in-situ SiC/Al-50Si composite exhibits excellent thermal and mechanical properties, including a high TC of ∼162 Wm-1K−1, a low CTE of ∼ 8.7 × 10-6/K, and a good bending strength of approximately 253 MPa at room temperature.

The Impact of Selected Eutectic Solvents on the Volatile Composition of Citrus lemon Essential Oil.

The development of new materials for the controlled release of molecules represents a topic of primary importance in medicine, as well as in food science. In recent years, eutectic solvents have been applied as releasing media due to their improved capacity to interact with specific molecules, offering a broad range of tunability. Nevertheless, their application in essential oil dissolution are rare and more data are needed to develop new generations of effective systems. Herein, three eutectic systems, respectively, composed of choline chloride and ethylene glycol (1:2 molar ratio), methyltriphenylphosphonium bromide and ethylene glycol (molar ratio 1:5), and choline chloride and glycerol (molar ratio 1:1.5) were tested as materials for the controlled release of an essential oil derived from Citrus lemon leaves. Through static headspace fractionation, followed by gas chromatographic analysis, the performances of the three systems were assessed. The specific composition of DESs was pivotal in determining the releasing polar molecules as aldehydes and alcohols. A sustainability ranking based on the EcoScale tool highlighted the superior characteristics of the choline chloride-glycerol DES.

Simultaneous extraction and deglycosylation for flavonoid analysis in Ginkgo biloba products using a two-phase deep eutectic solvent system

Total flavonoid content is one of the most important quality indicators of Ginkgo biloba leaves and its products, but the complex pretreatment procedures and the excessive use of organic solvents complicate the detection process. In response, an innovative and efficient two-phase deep eutectic solvent (DES) system—composed of an acidic hydrophilic DES and a hydrophobic DES—was developed to quantify flavonoids for quality control of G. biloba products. High-performance liquid chromatography (HPLC) detection conditions were optimized, followed by systematic screening and design of the two-phase DES system through adjustments to polarity, hydrophilicity, and acidity. Optimal pretreatment conditions were established through operating condition optimization. This approach enabled simultaneous extraction, deglycosylation, and enrichment of all flavonoids from G. biloba samples into the hydrophobic phase in a single step. Method validation showed strong linearity with a correlation coefficient (R2 > 0.9995). The detection (LOD) and quantification (LOQ) limits were between 0.35 and 0.37 mg/kg, and 0.92 and 0.96 mg/kg, respectively. The method also exhibited high sensitivity and accuracy, with a recovery rate of 96.91–100.39%. A greenness assessment with the ComplexGAPI tool confirmed this method’s eco-friendly advantages over conventional techniques, aligning well with green chemistry and economic principles. Ultimately, this technique effectively measured flavonoid levels in different G. biloba products. The method developed in this work not only enhances the efficiency of simultaneous extraction and deglycosylation by modifying the polarity, hydrophilicity, and acidity of the two-phase DES system, but also offers valuable insights for the advancement of environmentally friendly analysis technology for flavonoids.

Exploring residual stress analysis in the machining of hypoeutectic high chromium white cast iron alloys through the hole-drilling method

Abstract High chromium white cast irons (HCWCIs), ASTM A352, Type A and Class III, i.e., 25%Cr iron in as-cast condition consists of proeutectic austenite (γ-Fe), transformed martensite (α-Fe) and discontinuous Cr-rich, i.e., M7C3/ (Cr, Fe)7C3 type of carbides, which are hard and brittle in nature. Fully annealed thermal treatment was performed to improve iron’s machinability leading to fully pearlitic matrix with minor retained γ-Fe content. Eutectic (Cr, Fe)7C3 type of carbides are not affected by heat treatment processes. Resulting from corresponding manufacturing process, the magnitude and distribution of residual stresses (RSs) in as-cast and after machining were measured using hole-drilling method (HDM), as they are known to be harmful to corrosion and fatigue resistance. Furthermore, general metallurgical material characterisation was performed in as-cast and heat-treated conditions. As a result, this study revealed hardness variation, 547 and 555BHN in as-cast as compared to 327BHN in heat-treated condition. Furnace and actual cast component chemical analysis revealed a slight variation, especially between carbon (C) and chromium (Cr). Furthermore, eutectic type of carbides and precipitated secondary, i.e., (Cr, Fe)23C6 type of carbides within fully pearlitic matrix with minor amounts of retained γ-Fe were detected within the dominant matrix, i.e., pearlitic matrix in as-annealed condition. Detected magnitude and distributions of RSs on heat-treated sample resulted in higher tensile stresses in the surface and compressive in the interior as compared to sample in as-cast condition. Thus, this study was successfully in measuring RSs in as-cast and upon machining of hypoeutectic irons of HCWCI alloys using HDM.

Conformational Geometry Matters: The Case of the Low-Melting-Point Systems of Tetrabutylammonium Triflate with Fumaric or Maleic Acid.

For this article, the interaction of tetrabutylammonium trifluoromethanesulfonate (TBATFO) with either fumaric (FUM) or maleic (MAL) acid has been investigated. These acids are isomers and can be considered the trans and cis configurations of the same molecular geometry. When TBATFO is mixed with FUM, an eutectic point is obtained for a relative composition of 90-10 (molar ratio), with a melting point of ≈90 °C. If maleic acid is mixed with TBATFO, one obtains an inhomogeneous phase with the retention of a solid portion immersed in a liquid phase, even above 90 °C. DFT calculations helped to model the interaction between the components. It is suggested herein that TBATFO interacts more strongly with FUM than with MAL, due to possible interactions in two different sites for hydrogen bonding (HB) in FUM. In MAL, one of the HB sites is instead retained in the intramolecular interactions; therefore, fewer sites are available for intermolecular interactions. Infrared spectroscopy measurements have confirmed this scenario, in which the hydrogen bonds of the acid molecules are replaced by HB between the acid and the ionic couple: for both kinds of mixtures, the vibration region of the OH bonds is strongly affected by mixing. However, in the case of FUM, the vibrations of the SO3 group of the TFO anion are displaced, while they remain in practically the same frequency position in the case of MAL.

Simultaneous recovery of ammonium sulfate and ice from aqueous solution using eutectic freeze crystallization process

This study investigated the feasibility of eutectic freeze crystallization (EFC) process for ammonium sulfate (AS) salt recovery from 41 wt% AS solution. The EFC experiments were conducted using a 1 L double-jacketed crystallizer coupled with a recirculating chiller under varying freezing time, seed mass and seed size. The EFC process demonstrated successful AS salt recovery and water purification with the highest ice purity attained at 96.28 %. The construction of a binary AS-water phase diagram allowed the determination of the eutectic temperature, which was found to be −19.06 °C at 40 wt% of AS solution. The results indicated that the increase in freezing time enhanced the AS nucleation rate, growth rate, yield and mean product crystal size. The introduction of seeding not only provided well-controlled crystal nucleation and growth during EFC process, but also promoted the formation of larger, well-structured crystals and reduced agglomeration. Overall, the EFC process is a viable and promising option for recovering AS from wastewater, which offers high potential towards achieving zero liquid discharge goal, i.e. a sustainable and efficient approach in managing industrial effluent rich in ammonium and sulfate contaminants.

Experimental and Simulation Study on Enhancing Thermal Energy Storage and Heat Transfer Performance of Ternary Chloride Eutectic Salt by Doping MgO Nanoparticles

Experimental and Simulation Study on Enhancing Thermal Energy Storage and Heat Transfer Performance of Ternary Chloride Eutectic Salt by Doping MgO Nanoparticles

Force Fields for Deep Eutectic Mixtures: Application to Structure, Thermodynamics and 2D-Infrared Spectroscopy.

Parametrizing energy functions for ionic systems can be challenging. Here, the total energy function for an eutectic system consisting of water, SCN-, K+ and acetamide is improved vis-a-vis experimentally measured properties. Given the importance of electrostatic interactions, two different types of models are considered: the first (model M0) uses atom-centered multipole whereas the other two (models M1 and M2) are based on fluctuating minimal distributed charges (fMDCM) that respond to geometrical changes of SCN-. The Lennard-Jones parameters of the anion are adjusted to best reproduce experimentally known hydration free energies and densities, which are matched to within a few percent for the final models irrespective of the electrostatic model. Molecular dynamics simulations of the eutectic mixtures with varying water content (between 0 and 100%) yield radial distribution functions and frequency correlation functions for the CN-stretch vibration. Comparison with experiments indicates that models based on fMDCM are considerably more consistent than those using multipoles. Computed viscosities from models M1 and M2 are within 30% of measured values and their change with increasing water content is consistent with experiments. This is not the case for model M0.

Thermal analysis and modeling of phase equilibria in the NaCl–NaBr–Na2WO4 system

The phase complex of a three-component system of sodium chlorides, bromides and tungstates was studied for the first time using experimental and theoretical methods. It was found that the liquidus surface of the system consists of the crystallization fields of NaBr, Na2WO4, Na3ClWO4 compounds and NaClxBr1–x solid solutions. The differential thermal method of physico-chemical analysis (DTA) revealed the compositions and melting points of eutectic in the quasi–binary and three–component systems NaBr–Na3ClWO4 and NaCl–NaBr–Na2WO4, respectively. To establish the nature of the physico-chemical interaction in the system, three compositions were studied in the secondary triangle NaCl–NaBr–Na3ClWO4 by the DTA method, thermal effects of tertiary crystallization were not recorded on the DTA curves of these compositions, which is proof of the absence of a non-invariant composition in the NaCl–NaBr–Na3ClWO4 simplex. To determine the composition and melting point of the nonvariant composition located in the NaBr–Na2WO4–Na3ClWO4 simplex, a polythermal section located in the field of crystallization of sodium bromide and a nonvariant section emerging from the crystallization pole of sodium bromide passing through the point of joint crystallization of sodium chloride and the compound, with a constant decrease in the content of sodium bromide in the studied compositions before the onset of non-invariant crystallization process. The composition of the three-component eutectic of ED in molar percentages, crystallizing at 560оC with the following component content, has been determined: 7.5% NaCl; 38.5% NaBr; 54% Na2WO4. Based on data on the melting temperatures of the initial salts, compositions and crystallization temperatures of two- and three-component systems, a 3D-model of the “composition–temperature” phase complex in the temperature range 500–700оC was formed using theoretical methods. On the basis of the model, the isotherms of the liquidus surface and the T–x diagram of the polythermal section for which experimental studies were conducted was constructed. Also, as an example of using a 3D-model, the composition of the equilibrium phases released during cooling of an arbitrarily selected figurative point in the temperature range from 700 to 500оC. was calculated.

Grain refiner fabricated by spark plasma sintering for hypoeutectic Al-Si alloy cast and its refining ability

Grain refiner fabricated by spark plasma sintering for hypoeutectic Al-Si alloy cast and its refining ability