Journal of Chemical Thermodynamics最新文献

The excess and partial molar properties of binary liquid mixtures can be used to unveil the prevailing intermolecular interactions. The densities, ρ and speeds of sound, u for pure polyethylene glycol 200 (PEG 200), methyl methacrylate, ethyl methacrylate and their binaries (PEG 200 + methyl/ethyl methacrylate) have been measured over the entire composition range in the temperature range (293.15 to 323.15) K at 5 K intervals and at pressure, p = 100 kPa. The excess molar volume, excess isentropic compressibility, excess speed of sound, excess intermolecular free length, excess molar isentropic compressibility and excess acoustic impedance were evaluated using the experimental data. The partial and excess partial molar volumes/compressibilities of the components at each mole fraction and at infinite dilution have also been calculated. The results have been interpreted on the basis of prevailing intermolecular interactions as well as structural effects between like and unlike molecules. The results indicate the effect of the size of alkyl group on excess functions and interactions in these systems and the PEG-methacrylate interactions follow the order: methyl methacrylate > ethyl methacrylate. Scaled particle theory has also been used for the theoretical estimation of the speeds of sound and compared with experimental values. FT-IR spectra of pure PEG 200, methyl methacrylate, ethyl methacrylate and equimolar PEG 200 + methyl methacrylate/ethyl methacrylate mixtures were also recorded and analysed for better understanding of prevailing intermolecular interaction.

A comprehensive study of the thermodynamic properties of two ionic liquids 1-ethyl-3-methylimidazolium (EmimMS) and 1-butyl-3-methylimidazolium methanesulfonate (BmimMS) was carried out. The isobaric heat capacity of the crystal and liquid phases of EmimMS and BmimMS was determined in the temperature range from 80 to 380 K by vacuum adiabatic calorimetry. The heat capacities of EmimMS and BmimMS were assessed at temperatures from 5 to 80 K by the Kelly method. The temperature dependencies of EmimMS and BmimMS main thermodynamic functions were determined in the temperature range from 5 to 380 K (isobaric heat capacity C_p,m(T), standard entropy S^o_m(T), heat content H^o_m(T) – H^o_m(0), Gibbs energy content G^o_m(T) – H^o_m(0). Melting points and fusion enthalpies of EmimMS and BmimMS have been refined by DSC. The enthalpies of dissolution in water of EmimMS and BmimMS at 298.15 K were measured by the dissolution calorimetry. The standard enthalpies, entropies and Gibbs energies of EmimMS and BmimMS formation in the crystal and liquid state at 298.15 K were calculated from the experimental data. Comparison of the obtained thermodynamic characteristics with the literature data was carried out.

Solubility of trans-4-chlorocinnamic acid as a photomechanical molecular crystal material in twelve pure solvents (water, ethanol, methanol, n-propanol, isopropanol, n-butanol, isobutanol, acetonitrile, 1,4-dioxane, acetone, methyl acetate and ethyl acetate) were measured from 283.15 to 325.15 K at 101.2 kPa. The results showed that the trans-4-chlorocinnamic acid solubility increased with the temperature, the order is: 1,4-dioxane > acetone > n-butanol > ethanol > n-propanol > isopropanol > isobutanol > methanol > methyl acetate > ethyl acetate > acetonitrile > water. Powder X-ray diffraction pattern (PXRD) and differential scanning calorimetry (DSC) were used to identify and characterize the equilibrated solid phase samples. The solubility behavior and the solute–solvent interaction of trans-4-chlorocinnamic acid in each selected mono-solvent were explored by the empirical solvents polarity parameter (E_T(30)), hydrogen bonding, cohesive energy density, molecular structure, and Hansen solubility parameters (HSPs). In addition, the experimental solubility data were correlated by the modified Apelblat model and Yaws model, and the fitting results of this models were all satisfactory. The intermolecular forces were determined through molecular simulations, including Hirshfeld surface (HS) and Molecular Electrostatic Potential Surface (MEPS) analysis. The results showed that hydrogen bond can be formed between trans-4-chlorocinnamic acid and the selected solvents, which can help to further explain the dissolution behavior of trans-4-chlorocinnamic acid in the solvents.

The mole-fraction solubility of itraconazole in four aqueous blends of ethanol/isopropanol/DMSO/methanol within the temperature range of 283.15 to 323.15 K was experimentally obtained using the isothermal shake-flask method. Under the identical temperature and ethanol/isopropanol/DMSO/methanol composition, itraconazole solubility in DMSO+water is much higher than that in ethanol/isopropanol/methanol + water. At the same temperature, the solubility increases monotonically with organic solvent concentration. X-ray power diffraction analysis demonstrated that over the course of the investigations, there was no crystal transition or solvate formation. The modified van’t Hoff-Jouyban-Acree and Jouyban-Acree models adequately related the solubility to solvent composition and temperature, with relative average deviations (RADs) not exceeding 7.65 %. Furthermore, the extended Hildebrand solubility approach was utilized to quantitatively characterize the solubility behavior at 298.15 K for the mixtures of ethanol/isopropanol/DMSO/methanol plus water. In both instances, the RADs were maintained below 4.12 %. The solubility parameter and dipolarity-polarizability of solutions have a major impact on the solubility fluctuation, as indicated by the analysis of the linear solvation energy relationship. The preferential solvation of itraconazole at 298.15 K was examined using the efficient approach of inverse Kirkwood-Buff integrals. The preferred solvation parameters showed positive values in blends within rich and moderate ethanol/isopropanol/DMSO/methanol composition regions. This suggests that the organic solvents preferentially solvated itraconazole. When itraconazole dissolved in the blends, thermodynamic analysis of the entropy-enthalpy compensation and dissolution parameters revealed both an endothermic and an enthalpy-driven mechanism. Furthermore, the microscopic electrostatic characteristics of basicity and acidity were effectively demonstrated by means of the electrostatic potential of molecular surface. The −C=O and −N=groups of the itraconazole molecule, which link the five-membered ring, are the primary targets of the electrophilic attack. An independent gradient model based on Hirshfeld partition analysis was used to demonstrate the weak interactions between itraconazole and solvents.

This study presents the first investigation of the sublimation behavior of tin tetraiodide, SnI₄, using effusion-based techniques, within a low temperature range (313–340) K. The temperature range covered in the experiments was lower than in previously reported studies based on static methods. Knudsen Effusion Mass Loss (KEML) measurements were performed in the range of (317.1–339.6) K using effusion cells with different orifice sizes. The vapor pressures were measured in the range (0.13–1.13) Pa and were found to be independent of the orifice size. The standard molar enthalpy and Gibbs energy of sublimation at 298.15 K obtained by the Clarke and Glew fit of experimental data are (88.1 ± 0.9) kJ⋅mol⁻¹ and (38.96 ± 0.08) kJ⋅mol⁻¹, respectively. Knudsen Effusion Mass Spectrometry (KEMS) experiments were also performed in the range (313.3–331.7) K, resulting in a sublimation enthalpy value in good agreement with the KEML values and not negligibly higher vapor pressure values. KEMS vapor pressure data were also analyzed by the third-law method. A comparison of our experimental results with the literature data available for both sublimation and evaporation properties of SnI₄ is reported. Additionally, ancillary DFT and ab initio calculations were performed to estimate the molecular properties of SnI₄(g) and the extent of the gas-phase dissociation to SnI₂ and I₂.

As an anticancer drug, the mole fraction solubility of curcumin in subcritical water (SBCW) was determined by a static method. Experiments were performed at temperatures between 298.15–423.15 K and a constant pressure of 20 bar. With increasing temperature, the mole fraction of solubility showed a significant increase in the range of 0.03 × 10^-6< x ₂< 13.22  × 10^-6. For the correlation of experimental solubility data, linear, modified Apelblat, NRTL, UNIQUAC, and Wilson thermodynamic models were selected. Among the models, NRTL and modified Apelblat models had a better correlation with the experimental data with MPD% 6.94, 4.68, and RMSD×10⁵ 0.07, 0.04, respectively. Also, the thermodynamic functions such as Gibbs free energy, enthalpy, and entropy were calculated for the solubility process of curcumin in SBCW.

To prevent the wastewater containing 2-ethoxyethanol (2EE) from causing environmental pollution and economic waste, liquid–liquid extraction was used to recover 2-ethoxyethanol from wastewater in this study. The liquid–liquid equilibrium behavior of water + 2-ethoxyethanol + four solvents (propyl acetate, isopropyl acetate, n-butyl acetate, and isobutyl acetate) was investigated at 303.2 K and atmospheric pressure. The distribution coefficient (D) and separation factor (S) were used to compare and discuss the extraction efficiency of each system. The results indicated that all esters could effectively separate 2-ethoxyethanol from water. Among them, isobutyl acetate exhibited the highest values for D and S, demonstrating its superior separation capability. The experimental data were correlated with the thermodynamic model and interaction parameters were obtained. These parameters were verified using the GUI-MATLAB tool, and all four systems passed validation, confirming the reliability of the obtained binary interaction parameters. Furthermore, the root mean square deviation (RMSD) was used to assess the deviation between the experimental and regression values. The RMSD values for the NRTL and UNIQUAC models were 0.008 and 0.007, respectively. The interactions between 2-ethoxyethanol and water or esters were explored using σ-Profile, and it was found that esters with a branched chain structure provided better extraction. To explain the properties of the extractants microscopically, the interaction energies between 2-ethoxyethanol molecules and water or ester molecules, as well as the non-bonding energies of 2-ethoxyethanol in different media, were calculated.

The thermal behaviour of bathophenanthroline and bathocuproine has been studied using several techniques, namely, differential scanning calorimetry and thermogravimetry. To determine their respective enthalpies of sublimation, vapor pressure measurements were carried out using different methods, such as Knudsen effusion mass loss/mass spectrometry, isothermal thermogravimetry, and a quartz crystal microbalance technique. Furthermore, the enthalpies of sublimation were determined by measuring the heat change of the sublimation process using high-temperature Calvet microcalorimetry.

The results obtained in this work allowed the determination of the standard molar enthalpies of sublimation at 298.15 K, for bathophenanthroline and bathocuproine. The values obtained were (183.8 ± 2.2) kJ⋅mol⁻¹ and (206.2 ± 2.8) kJ⋅mol⁻¹, respectively. Additionally, the standard molar enthalpies of fusion were determined to be (30.4 ± 0.4) kJ⋅mol⁻¹ and (26.5 ± 1.6) kJ⋅mol⁻¹ for bathophenanthroline and bathocuproine, respectively. The analysis of the results allows a deeper understanding of the phase transition behavior for these compounds from the condensed to the gaseous phases, elucidating molecular decomposition and the inherent intermolecular forces governing the species.

The gaseous pvTx data of the binary mixtures for carbon dioxide (CO₂) + trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) and CO₂ + 3,3,3-trifluoropropene (R1243zf) were experimentally measured at 5 isotherms from 333.15 K to 393.15 K. The experiment used a Burnett apparatus and the highest experimental pressure exceeded 7 MPa. The standard uncertainties of temperature, pressure and mole fraction are 10 mK, 0.2 ∼ 0.8 kPa and 0.0015, respectively. The relative uncertainty of the molar density is 0.05 %. Based on the experimental data of pure components and mixtures, three-term truncated virial equations of state (EoS) were established. The relative root mean square deviations (RMSD) of virial EoS in calculating density of CO₂ + R1234ze(E) and CO₂ + R1243zf mixtures are 0.15 % and 0.05 %, respectively. The virial EoS obtained in this work were compared with REFPROP 10.0 and the literature data, and the virial coefficients were calculated and compared between the experimental value and the calculated value from virial EoS.

In this work, experimental Vapor-Liquid Equilibrium (VLE) data for the Isopropanol + Water system under vacuum conditions at 60 kPa and at 80 kPa, for which no experimental evidences have been found in the literature, are reported. The experimental investigation of the isobaric equilibrium has been carried out by GASP at the Process Thermodynamics laboratory (PT lab) of Politecnico di Milano by employing an all-glass dynamic recirculation still. The collected experimental data, together with those already available in the literature at other conditions, have been used for the evaluation of the thermodynamic model that best fits the data. Four different models have been considered and their performances have been checked through the calculation of the Absolute Average Deviation (AAD%). The lowest AAD% has been found for the UNIFAC model only for isobaric data, not for the isothermal points. The regression tool available in Aspen Plus® V14 has been used to fit the binary interaction parameters of the NRTL activity model.