Liquid Equilibrium Phase Diagrams Research Articles

Clean and efficient recovery of gallium–indium alloy from gallium-based liquid metal waste using a two-stage vacuum distillation method

Gallium (Ga) and indium (In) are rare metals widely used in the high-tech industry. Gallium-based liquid metal (G-LM) waste is produced during the preparation of liquid metal and related products. G-LM waste is a potential source of gallium and indium. In this study, the saturated vapor pressure, separation coefficient, and gas–liquid equilibrium phase diagram were determined using the simplified molecular interaction volume model. A two-stage vacuum distillation method was used to recover Ga–In alloy from G-LM waste. First, low-temperature vacuum distillation was used to recover 98.23 % of Zn under optimal conditions (1–5 Pa; 773 K; 60 min). Then, the Ga–In alloy was recovered through high-temperature vacuum distillation. Under the optimal conditions (1–5 Pa; 1523 K; 120 min), the recovery rates of gallium and indium were 85.14 and 95.23 %, and the content of Ga–In alloy in the product was 99.46 %. Compared with the traditional hydrometallurgical process for recovering gallium and indium, this process generates no exhaust gas or waste. In addition, this new method is simple, efficient, clean, and pollution-free. Overall, this new method for recovering Ga–In alloy provides a new avenue for comprehensively utilizing G-LM waste.

Characterization of choline chloride‐based deep eutectic solvent for anthocyanin extraction via aqueous two‐phase system: Physicochemical properties and liquid–liquid equilibrium phase diagram

AbstractThe purpose of this research is to characterize and explore the feasibility of deep eutectic solvent‐based aqueous two‐phase system (DES‐ATPS) for its potential application in the extraction and purification of anthocyanins. Various combinations and molar ratios of DES using choline chloride as hydrogen bond acceptor (HBA) and butanediol (BDO), ethylene glycol (EG), and lactic acid (LA) as hydrogen bond donor (HBD) were synthesized, screened, and investigated on its physicochemical properties. The binodal phase diagrams were developed as basis for the ATPS development. It was noted that LA‐based natural deep eutectic solvents (NADES) were highly polar and likely to enhance the solubility of anthocyanin in DES. Regardless, the simple molecular structure and low viscosity of EG‐ and BDO‐based DES enhanced the solubility of anthocyanin and recorded a monomeric anthocyanin content ranging from 10.52 ± 0.78 mg cyanidin‐3‐glucoside/g at 40°C and 10.78 ± 0.84 mg cyanidin‐3‐glucoside/g at 30°C, respectively. Lastly, the liquid–liquid equilibrium binodal curves were developed and ChCl:1,3‐BDO (1:4) and ChCl:1,4‐BDO (1:4) exhibited excellent phase‐forming ability, thus concluding its excellent potential for anthocyanin extraction through ATPS.

Design of Deep Eutectic Systems: Plastic Crystalline Materials as Constituents.

Deep eutectic solvents (DESs) are a class of green and tunable solvents that can be formed by mixing constituents having very low melting entropies and enthalpies. As types of materials that meet these requirements, plastic crystalline materials (PCs) with highly symmetrical and disordered crystal structures can be envisaged as promising DES constituents. In this work, three PCs, namely, neopentyl alcohol, pivalic acid, and neopentyl glycol, were studied as DES constituents. The solid–plastic transitions and melting properties of the pure PCs were studied using differential scanning calorimetry. The solid–liquid equilibrium phase diagrams of four eutectic systems containing the three PCs, i.e., L-menthol/neopentyl alcohol, L-menthol/pivalic acid, L-menthol/neopentyl glycol, and choline chloride/neopentyl glycol, were measured. Despite showing near-ideal behavior, the four studied eutectic systems exhibited depressions at the eutectic points, relative to the melting temperatures of the pure constituents, that were similar to or even larger than those of strongly nonideal eutectic systems. These findings highlight that a DES can be formed when PCs are used as constituents, even if the eutectic system is ideal.

Unveiling the mechanism of CO2-driven phase change in amine + water + glycol ether ternary mixture

BackgroundPhase separation solvents have been developed for CO2 capture with the advantage of low regeneration energy. Understanding the mechanism of phase change driven by CO2 capture is critical toward design of phase separation solvents. MethodsIn this work, the molecular information of σ-profile and simulated ternary liquid–liquid equilibrium (LLE) phase diagram obtained from a predictive modeling based on COSMO-SAC method is used to investigate the phase behavior of phase separation solvents before and after CO2 absorption. Significant findingsTernary mixtures of three selected amines [2-aminoethanol (MEA), 2-(ethylamino)ethanol (EAE), 2-(butylamino)ethanol (BAE)] + water + glycol ether, with different strengths of hydrophilicity of amines, exhibit three types of partially miscible behaviors. Upon absorption of CO2, amine reacts to form hydrophilic reaction products (carbamate + protonated amine), resulting in the change of the molecular interactions and immiscible behaviors. Our study shows that amines, such as EAE, having a balanced interaction with water and glycol ether (exhibiting small immiscible region) are potential candidates for amine + water + glycol ether based phase separation solvent for CO2 capture.

Separation of Li(I), Co(II), Ni(II), Mn(II), and Fe(III) from hydrochloric acid solution using a menthol-based hydrophobic deep eutectic solvent

The process of recovering valuable materials from lithium-ion batteries is important because of the economic and environmental problems associated with these batteries. In this study, a comprehensive process based on the combination of a hydrophobic deep eutectic solvent (HDES) for the extractive separation of Li(I), Co(II), Ni(II), Mn(II), and Fe(III) and subsequent recovery was developed. For the first time, Aliquat 336 and environmentally friendly L-menthol were combined to form HDESs. The solid–liquid equilibrium phase diagram of the Aliquat 336 and L-menthol mixture was analysed to determine the hydrogen bond donor and hydrogen bond acceptor molar ratios corresponding to eutectic points. The physicochemical properties of the two HDESs (density, refractive index, and viscosity) were determined. Thereafter, the extraction properties of a more convenient HDES corresponding to a 3:7 Aliquat 336/L-menthol molar ratio were investigated to determine the optimal conditions for metal separation. One mol/L HCl was added to the metal solution, and then HCl up to 3 mol/L and LiCl up to 5 mol/L were added, resulting in 99% recovery rates for each of Fe(III), Mn(II), and Co(II) for each extraction step. The stripping of each metal to the aqueous phase with an efficiency of up to 99% allows the reuse of both the metal and extractant. The Ni(II) separation via precipitation leads to a concentrated hydrochloric solution of Li(I), and thus, both metals can be reused. In the final process, Aliquat 336/L-menthol-based HDES was used as the only extractant for efficient metal separation, without using volatile and toxic organic solvents.

Solid–Liquid Phase Equilibria of the Quaternary system Li2SO4–LiBO2–Li2B4O7–H2O and the Ternary Subsystem LiBO2–Li2B4O7–H2O at T = 288.15 K and p = 0.1 MPa

The solubilities, densities, refractive indices, and pH values in the systems LiBO2–Li2B4O7–H2O and Li2SO4–LiBO2–Li2B4O7–H2O at 288.15 K were studied by the classical dissolution method in this paper. The solid–liquid equilibrium phase diagrams and the physicochemical property diagrams were constructed with the experimental results. The phase diagram of the ternary system is composed of two single-salt crystallizations of LiBO2·8H2O and Li2B4O7·3H2O, two solubility univariant curves, and one invariant point saturated with the above salts. The comparison for the phase diagrams in the ternary system at different temperatures shows that the solubilities of lithium metaborate and lithium tetraborate in this system are in a positive correlation with the temperature. The dry-salt diagram of the quaternary system consists of three single-salt crystallization fields for Li2SO4·H2O, LiBO2·8H2O, and Li2B4O7·3H2O, three univariant solubility curves, and one invariant point. The physicochemical properties in the two systems change regularly as the concentration increases in solution. The calculated densities and refractive indices with empirical equations are in good agreement with the experimental results.

Dissolution behavior and preferential solvation of diacerein in mixtures of (ethyl acetate/acetonitrile + ethanol) at several temperatures

Because the chemical structure of diacerein is plane structure, the solubility of diacerein is poor, and most of the products crystallized by solvent contain solvate, so it is difficult to get a large amount of diacerein without solvate. The present work demonstrates cosolvent as a successful technique to improve the dissolution property of diacerein. The solid liquid equilibrium phase diagram of diacerein in mixtures of (ethyl acetate/acetonitrile + ethanol) within the temperature range from (273.15 to 313.15) K was studied and represented using Jouyban-Acree model. The solubility profile of diacerein in two mixtures increased at first and then decreased with the increasing mass fraction of ethyl acetate/acetonitrile. In (ethyl acetate + ethanol) and (acetonitrile + ethanol) mixtures, the minimum mole solubility was obtained in pure ethanol, 5.085 × 10−5, and the maximum data in (ethyl acetate + ethanol) mixtures was 2.568 × 10−4 at the composition of w(ethyl acetate) = 0.8 (mass fraction), and 1.727 × 10−4 for (acetonitrile + ethanol) systems at w(acetonitrile) = 0.6, respectively. Preferential solvation parameters (δx1,3) of diacerein in two mixtures were evaluated by using the inverse Kirkwood-Buff integrals method, and it was all negative in ethanol-rich mixtures but positive at the mole compositions of ethyl acetate from 0.37 to 0.61, and with the range from 0.53 to 0.61 for acetonitrile. However, it should be noted that the positive preferential solvation parameters in acetonitrile + ethanol mixtures are lower than 0.01, near 0.002, and thus, a consequence of uncertainties propagation in IKBI calculations must be taken into account here. Moreover, the corresponding relative average deviations (RAD) of solubility correlation are 4.96% and 5.74%, respectively. The values of ΔHsolo were from 22.68 to 36.45 kJ·mol−1. The analysis of apparent thermodynamic properties shows that the dissolution process in all investigated solvent mixtures is an endothermic and entropy driven process.

Physicochemical Characterization and Simulation of the Solid-Liquid Equilibrium Phase Diagram of Terpene-Based Eutectic Solvent Systems.

The characterization of terpene-based eutectic solvent systems is performed to describe their solid–liquid phase transitions. Physical properties are measured experimentally and compared to computed correlations for deep eutectic solvents (DES) and the percentage relative error er for the density, surface tension, and refractive index is obtained. The thermodynamic parameters, including the degradation, glass transition and crystallization temperatures, are measured using DSC and TGA. Based on these data, the solid–liquid equilibrium phase diagrams are calculated for the ideal case and predictions are made using the semi-predictive UNIFAC and the predictive COSMO RS models, the latter with two different parametrization levels. For each system, the ideal, experimental, and predicted eutectic points are obtained. The deviation from ideality is observed experimentally and using the thermodynamic models for Thymol:Borneol and Thymol:Camphor. In contrast, a negative deviation is observed only experimentally for Menthol:Borneol and Menthol:Camphor. Moreover, the chemical interactions are analyzed using FTIR and 1H-NMR to study the intermolecular hydrogen bonding in the systems.

Liquid–Liquid Equilibria in Aqueous Mixtures of Phosphoric Acid with Two Primary Aryl Alcohols at T = (298.2, 308.2, and 318.2) K: Measurements and Correlation

This comparative study reports the measured liquid–liquid equilibrium (LLE) data and phase diagrams for the two ternary systems of {water + phosphoric acid + aryl alcohols (2-phenylethanol and 3-phenylpropanol)} at temperatures of (298.2, 308.2, and 318.2) K and atmospheric pressure (p = 0.1 MPa). Solubility data and mutual solubilities between the aryl alcohols and water were determined using turbidity measurements (cloud point titration method). Tie-line data were measured through acid–base titration and refractive index measurements. The results were validated through the Karl-Fischer titration method and mass balance calculations. The studied systems displayed Treybal's type-1 phase behavior, having one liquid pair that is partially miscible. The Othmer–Tobias correlation equation was applied to check the reliability of the tie lines. The experimental LLE data were correlated using the NRTL and UNIQUAC thermodynamic models, and the model binary interaction parameters between each pair of components were calculated. The results show the ability of these correlation models in representing the LLE data with acceptable average root-mean-square deviation (rmsd) values. As a result, the effect of temperature on the immiscibility region for the studied systems is small. For the studied systems, the separation factors are larger than unity, which means that the aryl alcohols have potential for separation of phosphoric acid from water.

Effect of Cation Structure in Quinolinium-Based Ionic Liquids on the Solubility in Aromatic Sulfur Compounds or Heptane: Thermodynamic Study on Phase Diagrams.

Experimental and theoretical studies on thermodynamic properties of quinolinium-based ionic liquids (ILs) based on bis(trifluoromethylsulfonyl)imide anion (namely N-butyl-quinoloinium bis(trifluoromethylsulfonyl)imide, [BQuin][NTf2], N-hexylquinoloinium bis(trifluoromethyl-sulfonyl)imide, [HQuin][NTf2], and N-octylquinoloinium bis(trifluoromethyl-sulfonyl)imide, [OQuin][NTf2]) with aromatic sulfur compounds and heptane, as a model compound of fuel were examined in order to assess the applicability of the studied ionic liquids for desulfurization of fuels. With this aim, the temperature-composition phase diagrams of 13 binary mixtures composed of organic sulfur compounds (thiophene, benzothiophene, or 2-methylthiophene) or heptane and ionic liquid (IL) were investigated at ambient pressure. A dynamic method was used to determine the (solid–liquid) equilibrium phase diagrams in binary systems over a wide composition range and temperature range from T = 255.15 to 365.15 K up to the fusion temperature of ILs. The immiscibility gap with an upper critical solution temperature (UCST) was observed for each binary system under study. The influence of the alkane chain length of the substituent on the IL cation and of the sulfur compounds (the aromaticity of the solvent) was described. The experimental (solid + liquid) phase equilibrium dataset were successfully correlated using the well-known NRTL equation.

Extensive Evaluation of Performance of the COSMO-RS Approach in Capturing Liquid–Liquid Equilibria of Binary Mixtures of Ionic Liquids with Molecular Compounds

A conductor-like screening model for real solvents (COSMO-RS) is presented as a predictive thermodynamic tool for estimating the liquid–liquid equilibrium (LLE) phase diagrams of the binary systems...

Construction and Application of a Ternary Solid–Liquid Phase Diagram of 3-Methyl-4-nitrobenzoic Acid and 3-Methyl-2-nitrobenzoic Acid in Methanol and Acetone

A ternary system solid–liquid equilibrium phase diagram is very useful to design industrial separation and purification operation. The ternary phase equilibrium for 3-methyl-4-nitrobenzoic acid (4,...

Solid−liquid phase equilibria of the quinary system containing lithium, sodium, calcium, strontium and chloride ions at 273.15 K and 101.325 kPa

The solid–liquid phase equilibria of systems LiCl–NaCl–CaCl2–SrCl2–H2O and CaCl2–SrCl2–H2O at 273.15 K and 0.1 MPa were investigated with the isothermal equilibrium method. The solid–liquid equilibrium phase diagrams were constructed with the experimental solubilities. The phase diagram in the ternary system consists of one univariant solubility curve saturated with solid solution (Ca,Sr)Cl2·6H2O, and one crystallization field of the solid solution. There are three invariant points, seven isothermal univariant curves, and five crystallization regions saturated with NaCl corresponding to (Ca,Sr)Cl2·6H2O, SrCl2·2H2O, LiCl·2H2O, CaCl2·4H2O and LiCl·CaCl2·5H2O in the dry-salt diagram of the quinary system. The areas of crystallization zones decrease according to the above order. The J(NaCl), J(H2O), refractive index and density of the solution gradually change regularly with the increasing of J(CaCl2) in the solution. These results on phase diagrams of the quinary system can supply theoretical reference for lithium salts and strontium salts separation from calcium chloride type brine.

Experimental solid-liquid equilibria of the ternary system Co(NO3)2 + Mn(NO3)2 + H2O at 20 °C, 0 °C and −15 °C

The solid–liquid equilibrium (SLE) phase diagram for the ternary systems of (water + cobalt nitrate + manganese nitrate) was experimentally determined via a method based on conductivity measurements under atmospheric pressure. Three isotherms were established at 20 °C, 0 °C and −15 °C. The characterization of solid phases formed in the three isotherms was conducted using atomic absorption spectroscopy (AAS) and X-ray diffraction (XRD), and was confirmed using chemical analysis. Three stable solid phases were identified in these isotherms are: ice, manganese nitrate hexahydrate Mn(NO3)2·6H2O and Cobalt nitrate hexahydrate Co(NO3)2·6H2O.

Thermal, physicochemical and spectroscopic studies on some novel organic complexes obtained by green synthesis

The solid–liquid equilibrium phase diagram and thermochemical studies on two binary organic systems involving N-methylurea (MU) with 4-nitrophenol (NP) and 3-nitrobenzoic acid NBA were studied. Both systems show the formation of an equimolar intermolecular compound (IMC) and two eutectics (E1 and E2) one on either side of the IMC. Thermodynamic parameters such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy and excess thermodynamic functions of intermolecular compounds and eutectics were calculated using the experimentally determined enthalpy of fusion by the DSC method. The spectroscopic studies, FTIR and NMR, of both the IMCs along with their parent compounds revealed the hydrogen bonding association between the parent moieties forming the complex. The findings were also confirmed by the appearance of new peaks in the powder XRD of the complexes in addition to their parent compounds.

Phase Diagrams in Representative Terpenoid Systems: Measurements and Calculations with Leading Thermodynamic Models

New experimental data on solid–liquid equilibrium (SLE) phase diagrams for binary systems {(−)-menthol or thymol + n-dodecane, or 1-dodecanol, or 2-phenylethanol} are presented. An influence of chemical structure of both terpenoid and solvent on the solubility curves is established and discussed. The new data are addressed and compared to the SLE data with a different set of solvents published previously. Modeling of SLE in the investigated mixtures with three modern thermodynamic models, namely, modified UNIFAC (Dortmund), perturbed-chain statistical associating fluid theory (PC-SAFT), and conductor-like screening model for real solvents (COSMO-RS), is presented as well. The predictive capacity of the studied approaches is confronted and compared with respect to their physical foundations for representation of components forming the systems as well as relevant intermolecular interactions governing thermodynamic behavior of the mixtures.

Prediction of Vapor–Liquid Equilibria for Pb–Pd and Pb–Pt Alloys Using Ab Initio Methods in Vacuum Distillation

The vapor–liquid equilibrium (VLE) phase diagrams of Pb–Pd and Pb–Pt alloy systems in vacuum distillation were obtained based only on pure-component properties and the structures of the atoms. The interaction energies between pairs of atoms were calculated from ab initio methods and were used as the input energy parameters for the Wilson equation. The calculated activity data of the components, using energy parameters which were obtained by ab initio methods, are in good agreement with the experimental data. It is revealed that a cluster size of eight atoms, optimized using the NVT ensemble at 300 K, a time step of 1 femtosecond, and the simulation time 10 ps gives a good representation of the liquid phase systems. This approach can be used to obtain accurate VLE predictions for alloy systems in vacuum distillation. The VLE phase diagram has a significant advantage in guiding experiment and industrial production in vacuum metallurgy.

Liquid–Liquid Equilibria for Systems Containing 4-Phenylbutan-2-one or Benzyl Ethanoate and Selected Alkanes

Liquid–liquid equilibrium (LLE) phase diagrams have been determined, by means of the critical opalescence method with a laser scattering technique, for the mixtures 4-phenylbutan-2-one + CH3(CH2)nCH3 (n = 10,12,14) and for benzyl ethanoate + CH3(CH2)nCH3 (n = 12,14). The systems are characterized by having an upper critical solution temperature (UCST), which increases with n. The corresponding LLE curves show a rather horizontal top and become skewed toward higher mole fractions of the polar compound when n is increased. Calorimetric and LLE measurements show that, for mixtures with molecules with a given functional group, interactions between aromatic molecules are stronger than those between homomorphic linear molecules (aromaticity effect). This has been ascribed to proximity effects arising from the presence of the polar group and the aromatic ring within the same molecule. Proximity effects become weaker in the sequence 1-phenylpropan-2-one >4-phenylbutan-2-one >1-phenylethanone and are more importan...

Separation of 2-Phenylethanol from Water by Liquid–Liquid Extraction with Ionic Liquids: New Experimental Data and Modeling with Modern Thermodynamic Tools

In this work, ionic liquids (ILs) are proposed as candidates for extractive removal of 2-phenylethanol (PEA) (well-known rose-like aroma compound) from its aqueous solutions. Four ILs based on different cations, namely, 1-hexyl-1-methylpyrrolidinium, 1-hexyl-1,4-diaza [2.2.2]bicyclooctanium, 1-(2-methoxyethyl)-3-methylimidazolium, and 1-(2-methoxyethyl)-1-methylpyrrolidinium, and bis(trifluoromethylsulfonyl)imide anion were under study. Thermodynamic data at ambient pressure are presented for pure ILs (including temperature-dependent density data and thermal characterization with DSC) as well as for binary systems {IL + water} and ternary systems {IL + PEA + water}. For the binary systems, (liquid + liquid) equilibrium phase diagrams were determined in temperature range T = (280–370) K. For ternary systems, (liquid + liquid) equilibrium was investigated at T = 308.15 K. An impact of the cation structure on the studied properties is established. The data obtained are discussed in terms of the selectivity a...

Solid–liquid phase equilibrium and ternary phase diagrams of ethenzamide-saccharin cocrystals in different solvents

The phase equilibrium for ethenzamide (EA) and saccharin (SAC) in ethanol, isopropanol and ethyl acetate were determined at 298.15 and 308.15 K under atmospheric pressure in this work. In ethanol and isopropanol, the two solutes dissolve incongruently and the diagrams are asymmetric, so excessive EA is required to isolate cocrystals. However in ethyl acetate, EA and SAC exhibit similar dissolution behavior, resulting in larger and more symmetric regions for EA-SAC cocrystal, which would be beneficial to enhance the control of EA-SAC cocrystallization process. In addition, the solubility of EA-SAC cocrystal was correlated by using a mathematical model based on both solubility product and solution complexation. The solubility of EA-SAC cocrystal as a function of SAC concentration was calculated. These new findings are of great importance to control the cocrystallization process of EA-SAC.