Journal of Chemical Thermodynamics最新文献

In order to recover and reuse pure refrigerants from the mixtures used in waste refrigeration facility, it is necessary to find a good way for separation. Due to the extremely low vapor pressure and good selectivity, ionic liquids (ILs) are regarded as promising entrainers for the extractive separation process of azeotropic or near-azeotropic mixtures. Phase behavior of refrigerant with ILs is the basic property in the design of selective absorption-separation process. In this work, the solubility of 3,3,3-trifluoropropene (R-1243zf) and ethyl fluoride (R-161) with trihexyltetradecylphosphonium chloride ([P_6,6,6,14][Cl]) were measured based on the isochoric saturation method. The experimental temperature range was from 283.15 K to 343.15 K. Five activity coefficient models, including Margules, van Laar, Scatchard-Hamer, Wilson and non-random two-liquid (NRTL) model, were used to correlate the experimental data, and the results were discussed. In addition, based on the literature data, the separation capacities of different ILs for refrigerant blends composed of R-1243zf or R-161 were investigated.

Deep eutectic solvent (DES) shows excellent absorption performance in the field of CO₂ capture. It is considered as a new green absorption solvent to replace monoethanolamine. In the industry, the presence of water not only affects the structural stability of the solvent, but also affects its thermophysical properties. In this work, three kinds of hydrophobic DES were prepared. Based on the study of their structural characteristics and thermal stability, the density and viscosity of DES with water mixture were measured in the temperature range of 298.15 ∼ 338.15 K at atmospheric pressure. It was demonstrated that the trace water did not destroy the structure of DES, but it formed hydrogen bonds with DES. The increase water destroyed the structure of DES and formed hydrogen bonds with hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA), respectively. Moreover, the hard sphere model was applied to study the viscosity, and after introducing the binary interaction parameter, the average absolute relative deviation of the mixture reduced to 4.4 ∼ 7.7 %.

2′,4′-Dichloro-5′-fluoroacetophenone is a key intermediate in the preparation of ciprofloxacin hydrochloride, a broad-spectrum quinolone antibacterial drug. Wherein, crystallization and solid–liquid equilibrium thermodynamics play an irreplaceable role in the separation and purification of 2′,4′-Dichloro-5′-fluoroacetophenone. Therefore, in this work, the solubility of 2′,4′-Dichloro-5′-fluoroacetophenone was measured by dynamic method in eight different solvents and range from 273.15 K to 288.15 K. The results showed that the solubility of 2′,4′-Dichloro-5′-fluoroacetophenone increased with increasing temperature. Further analysis showed that the solubility of 2′,4′-Dichloro-5′-fluoroacetophenone increased with increasing carbon chain length in ester solvents. Single crystals of 2′,4′-Dichloro-5′-fluoroacetophenone were successfully prepared and the result reveals that the Cl⋯H, O⋯H, and F⋯H interactions dominated the packing and long-range order of the crystals. Then, different thermodynamic models were employed to describe the thermodynamic behavior of 2′,4′-Dichloro-5′-fluoroacetophenone. The calculated ARD% and RMSD values show that the correlation results are in good agreement with the experimental data, and the Van’t Hoff equation has the best regression performance. Finally, it is interesting to find that the contribution of entropy and enthalpy change to dissolution of 2′,4′-Dichloro-5′-fluoroacetophenone tends to be equal with increasing temperature.

In the present work some thermochemical properties of 1,3-diphenylguanidine and 1,3-di-o-tolylguanidine were determined experimentally. To achieve this goal, differential scanning calorimetry was used to obtain purities, temperatures of fusion, enthalpies of fusion, entropies of fusion and heat capacities of the crystal phase as a function of temperature. Using thermogravimetry, the loss rate mass was measured for the crystal phase, and by applying the Langmuir equation the vapor pressure was estimated as a function of temperature, the enthalpy of sublimation was calculated by means of the Clausius-Clapeyron equation. Additionally, the entropy of sublimation and the Gibbs energy of sublimation were derived. With combustion calorimetry in a static bomb, the massic combustion energy was obtained and the standard molar enthalpy of formation in the crystal phase was determined. By combining the enthalpy of formation in the crystal phase and the enthalpy of sublimation, the standard molar enthalpy of formation in the gaseous phase was obtained for two arylguanidines. With the experimental data, the energetic effect due to the presence of two methyl groups in 1,3-di-o-diphenylguanidine was analyzed.

Hydrophobic deep eutectic solvents (HDESs) are considered as green solvents and have been developed rapidly in recent years, which are widely used in diverse applications. In this study, we introduce a binary system composed of 2-n-octyl-4-isothiazolin-3-one (OIT) as a novel hydrogen bond acceptor (HBA) and 1-decanol as a hydrogen bond donor (HBD) under atmospheric pressure. The fundamental physicochemical properties, including density and dynamic viscosity, of the binary systems with various mole ratios were measured at temperatures of 293.15 K, 303.15 K, 313.15 K, 323.15 K, and 333.15 K. The excess molar volume ($V_m^E$), viscosity deviation ($\Delta \eta$) and excess Gibbs free energy (${\Delta G}^{\ast E}$) for activation of viscous flow were calculated and fitted according to the Redlich-Kister type polynomial equation. Furthermore, the spectral analysis (FTIR, UV–vis and ¹H NMR) confirmed the presence of intermolecular hydrogen bonding in the binary systems. In addition, quantum chemical calculations revealed that there may be multiple modes of hydrogen bond formation between OIT molecule and 1-decanol molecule. However, selecting the most energetically favorable point, the most prominent hydrogen bond was found to be between the amide O atom of OIT and the hydroxyl H atom of 1-decanol.

The cloud–point method was used to determine temperatures located on the binodal surface for several nonaqueous two-phase systems containing formamide, and: {1–pentanol + NaBr} or {1–pentanol + NaNO₃}, or {1–butanol + NaNO₃}, or {1–butanol + D–sorbitol}, or {acetonitrile + D–fructose}. For comparison purposes, the measurements were made in the water + acetonitrile + D-fructose system. The measured temperatures ranged from about 0 to 90 °C. The experimental data were described by the NRTL model as well as through several empirical equations with the parameters depending on temperature. Finally, the paper discusses the advantages and disadvantages of individual solutions.

Ionic liquids (ILs) constitute a captivating class of materials that has garnered significant attention from research and industrial applications, being recognized as promising substitutes for organic solvents in industrial processes. Consequently, comprehensive experimental physicochemical characterization, explicitly focusing on density data complemented by computational tools, is imperative. In pursuit of this objective, the present study explores the density behavior, both experimentally and computationally, of three iodide-based ionic liquids under high-pressure and high-temperature (HPHT) conditions. Here, it was studied the alkyl chain impact on density for 1-propyl-3-methylimidazolium iodide ([C₃C₁Im][I]), 1-butyl-3-methylimidazolium iodide ([C₄C₁Im][I]), and 1-hexyl-3-methylimidazolium iodide ([C₆C₁Im][I]) ILs. The vibrating tube method was utilized to determine the density over a range of pressure (P = 0.20 to 100.00 MPa) and temperature (T = 298.15 to 398.15 K). The density of the ionic liquids (ILs) was found to be influenced by the length of the cation alkyl chain, exhibiting the following sequence of increasing density: [C₆C₁Im][I] < [C₄C₁Im][I] < [C₃C₁Im][I]. Tammann-Tait equation was used to correlate experimental density data, resulting in an average absolute relative deviation ($\%AARD$) less than 0.008 % for [C₆C₁Im][I] and [C₄C₁Im][I], and less than 0.025 % for [C₃C₁Im][I]. The ILs density values were used to determine the isothermal compressibility (${\kappa }_T$), the isobaric expansivity (${\alpha }_p$), the thermal pressure coefficient (${\gamma }_v$)_, and the internal pressure ($P_i$). These results revealed the structural impact of the alkyl chain on packing efficiency and its relationship with its physicochemical properties. Furthermore, ionic liquid density was estimated by using four group contribution estimation methods. Among these methods, the one proposed by Paduszynski and Domanska provided the best density estimative with a maximum $\%AARD$ of 1.09 %.