Solid Liquid Phase Equilibrium Research Articles

Solid-liquid phase equilibrium of trans-cinnamic acid, p-coumaric acid and ferulic acid in water and organic solvents: Experimental and modelling studies

The solubility of the trans isomers of cinnamic acid, p-coumaric acid and ferulic acid was measured in water and seven organic solvents (methanol, ethanol, 1-propanol, 2-propanol, 2-butanone, ethyl acetate and acetonitrile), at 298.2 K and 313.2 K, using the analytical shake-flask technique. The melting temperatures and enthalpies of the solutes were studied by differential scanning calorimetry, while solute solid structures were identified by powder and single X-ray diffraction.The NRTL-SAC model was applied to calculate the solubility of trans-cinnamic acid and trans-ferulic acid in pure solvents. For trans-p-coumaric acid, the NRTL-SAC was combined with the Reference Solvent Approach, as the solute melting properties could not be determined. The global average relative deviations (ARD) were 32% and 41%, in the correlation and prediction stages, respectively. The Abraham solvation model was also applied. The global ARD were 20% for correlation and 29% for predictions, which can be considered very satisfactory results for these semi-predictive models.

Solid-Liquid Phase Equilibria in the Quaternary System (NaCl–KCl–SrCl2–H2O) at 288.15 K

Phase equilibria of the quaternary system (NaCl–KCl–SrCl2–H2O) at 288 K are studied by the isothermal dissolution equilibrium method. The liquid phase was subjected to chemical analysis, and the corresponding solid phase was identified via X-ray diffraction. The phase diagram was plotted according to the experimental data. In the system of (NaCl–KCl–SrCl2–H2O), there are one invariant point, three univariant curves and three crystallization regions. The invariant point corresponding to NaCl + KCl + SrCl2 · 6H2O + Liquid, three crystallization regions corresponding to the NaCl, KCl, SrCl2 · 6H2O. Double salt or solid solution was not formed between the three original components NaCl, KCl and SrCl2 · 6H2O that without dehydration. The crystallization field of KCl is the largest, it is also found that strontium chloride has the salting-out effect on NaCl and KCl in this quaternary system.

Solid-liquid equilibria and thermodynamic correlation for the ternary system (KCl + PEG10000/20000 + H2O) at 288.2 K and 298.2 K

This work finished measuring the phase equilibria of ternary systems {KCl + polyethylene glycol (PEG) 10000/20000 + H2O} at 288.2 and 298.2 K. The solubility, density and refractive index were determined and corresponding diagrams were plotted in this work. There was only solid–liquid phase equilibrium existing in the ternary systems {KCl + PEG10000/20000 + H2O} at 288.2 K and 298.2 K. All of the phase diagrams of four systems are divided into three parts which respectively are the regions of unsaturated homogeneous liquid (L), one liquid and one solid KCl (L + S), and one liquid and two solids KCl and PEG (L + 2S). In addition, the effects of molar mass of PEG (PEG1000/4000/10000/20000) and temperature (288.2 K and 298.2 K) on phase equilibria were discussed. Results show that the sizes of regions of (L) and (L + S) increased and that of (L + 2S) decreased with the increase of temperature, and the regions of (L) and (L + S) decreased and that of (L + 2S) increased with the increase of the molar mass of PEG. The modified Pitzer model was adopted as the equilibrium thermodynamics model to correlate the experimental data. Comparing the experimental data and calculated dada, it can give a precise result with small error.

Experimental determination and computational analysis of solid–liquid phase equilibrium of nifedipine in twelve pure solvents

Nifedipine is an oral calcium channel blocker in clinical practice, and widely used to prevent and treat heart diseases. In this work, the equilibrium solubility of nifedipine (NIF) in twelve pure solvents including alcohols and esters was determined by static method at temperatures ranging from 283.15 K to 323.15 K. In all studied solvent systems, the solubility increases monotonously with increasing temperature. Besides, the effect of solvent properties on solid–liquid phase equilibrium of NIF was investigated. The results show that the solubility of NIF correlates well with the solvent properties in alcohol solvents but no obvious correlation can be found in ester solvents. In addition, the solubility data was correlated with the modified Apelblat equation, λh equation, van't Hoff equation and NRTL model, and the overall fitting ARD% are 0.94%, 2.15%, 2.75% and 4.03% respectively. Therefore, themodified Apelblat equation achieves the best fitting performance. Furthermore, in order to quantitatively study how the solute–solvent interaction affects the solubility, the solvation free energy was calculated by the molecular dynamic (MD) simulation. The absolute values of solvation free energy of esters (−18.96 to −20.32 kJ·mol−1) are higher than those of alcohols (−15.21 to −17.54 kJ·mol−1), which is consistent with the order of solubility values. Moreover, COSMO-RS σ-profiles were employed to qualitatively describe the intermolecular interactions.Finally, the COSMO-RS model was employed to predict the solubility of NIF in the studied solvents. The results show a good performance on predicting the solubility of NIF though the deviations existed in some cases.

Effects of Temperature and Solvent Properties on the Liquid–Solid Phase Equilibrium of γ-Pyrazinamide

The thermodynamic solubility of γ-pyrazinamide in 13 solvents (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, acetone, acetonitrile, water, 1,4-dioxane, methyl acetate, ethyl acetate, and n-propyl acetate) was measured by a dynamic method from 278.15 to 318.15 K. The results were modified by four models (λh equation, Apelblat equation, Wilson model, and nonrandom two-liquid (NRTL) model), and all of the relative standard deviation (RSD) values were less than 6%, indicating that the correlated data is in good agreement with the experiments. The thermodynamic parameters of mixing (ΔmixH, ΔmixG, and ΔmixS) were calculated by the NRTL model. Furthermore, the physicochemical properties of different solvents were investigated to visualize the solvent effects. The results indicated that for the ester and alcohol systems, the “like dissolves like” principle and mass transfer rules were the main factors that affect the solubility, and for other solvents, hydrogen bond donor propensities played the key role.

Molecular dynamics study of the thermodynamic and kinetic properties of the solid-liquid interface in FeMn

The solid-liquid phase equilibria as a function of temperature and composition has been computed for the Fe-Mn system using a semi-grand canonical Monte Carlo technique. Interaction between atoms were modeled using a second nearest neighbor modified embedded atom method potential. In addition, the excess solid-liquid interfacial free energy (γ) and its anisotropy has been computed from the capillary fluctuation method. The results indicate that there is very little variation in γ with temperature/composition. We also propose a new MD simulation method for computing solute trapping behavior that is able to access relatively low interface velocities. The segregation coefficient as a function of velocity for the Fe-Mn system was determined for three temperatures and the results are discussed within the framework of previously proposed theoretical models.

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,...

The effect of solvents on solid-liquid phase equilibrium of 1,3-Di-o-tolylguanidine

The crystal structure of 1,3-Di-o-tolylguanidine (DOTG) were investigated, as well as the thermodynamic properties about the solid-liquid phase equilibrium. The intermolecular interactions examined by Hirshfeld surface analysis demonstrate that the N-H···N and C-H···C interactions are dominant in the solid-state structure of DOTG. The solubility of DOTG in thirteen pure solvents (ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol, 2-butanol, 1-pentanol, propyl acetate, isopropyl acetate, acetone, butanone, acetonitrile, 1,4-dioxane) was measured by a gravimetric method from 283.15 K to 323.15 K at atmospheric pressure. According to the experimental results, the solubility of DOTG in all solvents increase with the increase of temperature. The determined solubility data were correlated using the Apelblat equation, λh equation, van't Hoff equation and the NRTL model. Additionally, the effects of solvent properties on the solubility of DOTG were discussed in terms of solvent polarity, hydrogen bond and cohesive energy density. Furthermore, the mixing thermodynamic properties of DOTG were studied in selected solvents based on the NRTL model, showing that the process of DOTG dissolving is spontaneous and entropy-driving. • The solubility of DOTG increases with temperature in thirteen systems. • The experimental data was well correlated by the Apelblat, van't Hoff, λh and NRTL models. • Thermodynamic analyses were performed based on functions of mixing. • The structure properties of DOTG crystal were investigated.

Solid–liquid phase equilibrium and thermodynamics analysis of 2,2,2-trichloroacetamide in different solvent systems

The knowledge of solid-liquid equilibrium data and solution thermodynamics of 2,2,2-trichloroacetamide (TCAcAm) in different solvents are essential for its synthesis, purification and further theoretical studies. In this paper, the solubility of TCAcAm in fifteen mono solvents of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, 2-butanone, acetone, ethyl acetate, 2-pentanone, acetonitrile, methyl acetate and ethyl formate was obtained through a gravimetric method at the temperature from 272.15 to 324.15 K under ambient pressure. The mole fraction solubility of TCAcAm in mono solvents showed an increasing trend with increasing temperature, and the phase equilibrium data in ketones and esters was much larger than that in alcohols. The experimental solubility can be well correlated using several thermodynamic models, such as the modified Apelblat equation, λh equation, non-random two-liquid (NRTL) model and the Wilson model. The obtained maximum relative average deviation (RAD) and root-mean-square deviation (RMSD) were 6.02 × 10−3 and 2.086 × 10−3 respectively. Besides, the dissolution enthalpy, entropy, and Gibbs free energy were calculated on the basis of thermodynamic relations and the Wilson model, which revealed that the dissolution of TCAcAm was a spontaneous and endothermic process.

Physicochemical and dissolution properties of ezetimibe\u2013aspirin binary system in development of fixed-dose combinations

The objective of this work was to investigate binary pharmaceutical mixtures of ezetimibe (EZT) and aspirin (ASA) in order to identify whether the occurrence of eutectic in this system has an effect on EZT dissolution improvement. Ezetimibe–aspirin (EZT–ASA) solid dispersions prepared by grinding in the whole range of compositions were characterized using differential scanning calorimetry (DSC) for purpose to describe solid-liquid phase equilibrium diagram. The occurrence of interactions between ingredients was excluded by Fourier transform infrared spectroscopy and X-ray powder diffractometry. Dissolution studies have shown that the mixtures containing from 10 to 60 mass% of EZT (53.5 mass% of EZT in eutectic composition) have released ezetimibe faster than a sample of pure drug. Moreover, ASA is released more quickly from all obtained dispersions than from powder alone. Our studies have shown that obtained mixtures are useful to obtain the fixed-dose combinations, capable to deliver these two APIs together in a single system with enhanced dissolution of EZT and ASA.

Determination, Construction, and Evaluation of Ternary and Quaternary Solid–Liquid Phase Equilibrium of Uric Acid, Adenine, and Guanine in Water

In this work, nine ternary phase diagrams and three quaternary phase diagrams of different systems at 298.15, 308.15, and 318.15 K were constructed. The ternary solid–liquid phase equilibrium of (u...

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.

Solubility measurement and solvent effect of Doxofylline in pure solvents and mixtures solvents at 278.15–323.15K

Abstract The solid-liquid phase equilibrium solubility of Doxofylline was measured and discussed in ten pure organic solvents and co-solvent mixtures of acetonitrile + ethanol (+or water) at temperature range from 278.15 to 323.15 K. Results indicated that experimental mole fraction (x) of Doxofylline in ten neat solvents followed this order: acetonitrile > tetrahydrofuran > benzene > acetone > ethyl acetate > methanol > 1-propanol ≈ 2-propanol > ethanol ≈ water, and solubility increased with temperature increasing. Moreover, experimental solubility of Doxofylline firstly increased and then declined with the mass fraction increasing of acetonitrile in acetonitrile + ethanol (+or water) mixture solvents at each temperature. Hansen solubility parameter and solvent effect were used for explaining and discussing solubility rule of Doxofylline in selected solvents. Model correlation indicated the NRTL model was the most suitable than other models to predict solubility of Doxofylline in pure solvents and Sun model was better than other models in mixture solvents with accompanied by temperature and composition. Furthermore, thermodynamic properties of standard molar enthalpy, molar Gibbs free energy and molar entropy in solution was calculated and discussed.

Solid-liquid phase equilibrium of phenylphosphonic acid in three binary solvents: Determination, correlation and molecular simulation

Abstract In this research work, solubility of pyrethroid insecticide phenylphosphonic acid (PPOA) in three binary solvents including methanol (MtOH) + ethyl acetate (EtAC), ethanol (EtOH) + EtAC at (278.15 to 323.15) K and 1,4-dioxane + EtAC at (288.15 to 323.15) K was investigated by laser monitoring method at 0.1 MPa. Solubility of PPOA increased with the increasing temperature while decreased with the increasing mass-fraction of EtAC. The solubility behavior was studied by molecular simulation. The solute-solvent interaction (Einter) suggested that solubility of PPOA increased with values of Einter increasing and there existed the strong interactions between PPOA and most selected binary solvents except 1,4-dioxane + EtAC. The radial distribution function (RDF) between two components of mixed solvent indicated that the tendency to aggregation of two components molecules increased with the increment of corresponding mole fraction of binary solvents. It also confirmed to some extent that the solute – solvent interaction energy would be weaken and the PPOA solubility in binary selected decreased. At the same time, it was found that the hydrogen bond existed in binary solvents namely “MtOH + EtAC and EtOH + EtAC”. So solubility of PPOA resulted from the integrated effect of solute – solvent and solvent – solvent interactions. Moreover, experimental solubility values were correlated by four multi-component activity coefficient models including Wilson, NRTL, Margules and UNIQUAC model. Four thermodynamic functions provided good correlations with solubility values. Furthermore, thermodynamic properties of mixing process were calculated by Wilson equation and corresponding solubility data. Mixing process was entropy-driven in selected solvents and exothermic in most binary solvents except EtAC and 1,4-dioxane (w1 = 0.2016) + EtAC.

Phase Equilibria of the Ternary Systems ((NH4)2SO4–MNSO4–H2O) and ((NH4)2SO4–MGSO4–H2O) at 303.15 K

In this work, the solid–liquid phase equilibria and physicochemical properties of ((NH4)2SO4–MnSO4–H2O) and ((NH4)2SO4–MgSO4–H2O) systems at T = 303.15 K have been determined by the isothermal solu...

Solid-liquid phase equilibrium and solution thermodynamics of 2-chlorobenzenesulfonamide in 16 mono solvents at temperature ranging from 273.15 K to 324.65 K

Abstract The synthesis and separation processes of chemical intermediate is based on the knowledge of its solid-liquid phase equilibrium with solvents in industry. In this work, the solubility of 2-chlorobenzenesulfonamide in 16 single pure solvents including methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, acetone, 2-butanone, 2-pentanone, cyclohexanone, cyclopentanone, ethyl acetate, methyl acetate, ethyl formate, acetonitrile and tetrahydrofuran was determined at temperature range from 273.15 to 324.65 K and atmospheric pressure. The mole fraction solubility of 2-chlorobenzenesulfonamide in all selected mono solvents was enhanced by an increase in temperature. In addition, the experimental data were further correlated by the modified Apelblat equation, λh equation, NRTL model and Wilson model. The values of RAD with NRTL equation were smaller than those with other three models, and thus the NRTL model offered the best fitting performance. The thermodynamic functions of dissolution including enthalpy, entropy, and Gibbs energy were derived, and the results expectedly suggested a spontaneous and entropy-driven mixing process. All the crystallographic and thermodynamic data reported in this study provides the fundamental data for designing and optimizing of the reaction and crystallization processes of 2-chlorobenzenesulfonamide.

Determination and Modeling of Solid–Liquid Equilibrium for the Ternary System of l-Pyroglutamic Acid + l-Glutamic Acid + Water at T = 298.15–328.15 K

The solid-liquid phase equilibrium for the ternary system of L-Pyroglutamic acid + L-Glutamic acid + water was determined experimentally by the isothermal solution saturation method at temperatures of 298.15, 308.15, 318.15, and 328.15K under normal atmosphere. According to the obtained solubility data, four ternary phase diagrams and the variable-temperature phase diagram were constructed. Two pure solids, pure L-Pyroglutamic acid and pure L-Glutamic acid, were generated in the L-Pyroglutamic acid + L-Glutamic acid + water system. In the phase diagrams, there were in all three crystallization zones, two cosaturated solubility curves, and one cosaturated point. The variable-temperature phase diagram for the ternary system of L-Pyroglutamic acid + L-Glutamic acid + water could be used for separation and purification L-Pyroglutamic acid and L-Glutamic acid from its mixture. The data of solid-liquid phase equilibrium were correlated and computed with the NRTL model and Wilson model. The RMSD (root mean squar...

The effect of solvents on solid-liquid phase equilibrium of Dimethyl sulfone

The structure and properties of Dimethyl sulfone (DMSO2) were investigated in both solid state and solution phase. In particular, the effect of four categories of solvent properties including hydrogen bonding donor and acceptor propensity, solvent polarity and cohesive energy density on solid-liquid phase equilibrium of DMSO2 were examined in detail. The intermolecular interactions derived from Hirshfeld surface analysis demonstrate that the CH⋯O interactions are dominant in crystal packing of DMSO2. The equilibrium solubility of DMSO2 was then determined in twelve monosolvents including water, straight and branch chain lower alcohols, and esters using gravimetrical method in the temperature ranging from 283.15 to 323.15 K. As expected, the solubility data is positively correlated with temperature, and DMSO2 bears the highest solubility in methyl acetate among all studied solvents. Further, it was found that the solubility of DMSO2 shows good correlation with cohesive energy density or the polarity of solvents except for the two lower alcohols of branch chain. The latter is likely due to other factors of solvent molecule involved such as steric hindrance, shape and size. Finally, the experimental data were well fitted by four thermodynamic models, and the modified Apelblat equation achieves the best fitting performance.

Determination and Calculation of Phase Equilibrium for Aqueous Ternary System (NH2)2CO+KCl+H2O at 283.15K

The solid-liquid phase equilibrium for ternary system (NH2)2CO+KCl+H2O was determined by isothermal saturation method at 283.15K under atmosphere pressure. The isothermal phase diagrams was drawn in according to the measured solubility data. There are one co-saturated point and two pure solids occurred in this ternary system. The solid phases were confirmed by Schreinemaker’s wet residue method and X-ray powder diffraction. Two thermodynamic models, Wilson model and NRTL model, were used to calculate the solubility data. The value of root mean-square deviation in Wilson model and NRTL model for this ternary system was 0.22 and 0.66 respectively, and the value of relative average deviation was 0.61% and 2.33% respectively, which indicated that the calculated data and the experimental results are nearly consistent.

Solid-liquid phase equilibrium determination and correlation of ternary systems NH4Cl+AlCl3+H2O, MgCl2+AlCl3+H2O and SrCl2+AlCl3+H2O at 298 K

The equilibrium data (solubility, density and refractive index) of three aqueous ternary systems NH4Cl + AlCl3+H2O, MgCl2+AlCl3+H2O, and SrCl2+AlCl3+H2O at 298 K were measured by isothermal dissolution method, and the corresponding diagrams were plotted. The phase diagram shows that these three systems are simple eutectic type, and neither double salt nor solid solution formed. Three ternary systems all have one ternary invariant point, two isothermal dissolution curves and two crystallization fields. The equilibrium thermodynamics data of three aqueous ternary systems at 298 K were correlated by using the Pitzer thermodynamic model. Result shows that the calculated values are consistent well with the experimental ones.