Journal of Chemical Thermodynamics最新文献

The increasing concerns of global warming impact of traditional HFC refrigerants drives the requirement for alternatives more urgent. Due to the excellent properties (zero ODP, extremely-low GWP, nonflammable, nontoxic, etc.), 3,3,3-Trifluoropropene (R-1243zf) is attracting a lot of fashionable attention in the refrigeration and air conditioning (RAC) industry. To better understand the oil existence influence on the performance of an evaporator, the vapor–liquid-phase equilibrium were measured for R-1243zf with PAG 68, PEC4, and POE 85 oils by an isochoric method between (298.15 and 343.15) K. The NRTL model was applied to correlate the phase-equilibrium data. The pressure-enthalpy-vapor quality (p-h-X) diagrams were plotted for R-1243zf and R-1243zf/lubricant blends with different oil-circulation mass fractions (C_g), and the differences in enthalpies were analyzed. There is a critical vapor quality (X_cri) between the isotherm curves. On the left side of X_cri, isotherm curves are almost identical. On the right side of X_cri, these curves separated gradually especially at high vapor quality.

Speed of sound data are reported for (carbon monoxide + ethane) and (carbon monoxide + propane) mixtures in the gas region at mole fractions of carbon monoxide of 0.25, 0.5 and 0.75 in the temperature range from 273.15 K to 350 K for mixtures containing ethane, and compositions x_CO = 0.5 and 0.75 at T = (260 to 350) K for mixtures with propane. Measurements are performed by means of a spherical acoustic resonator with an expanded relative uncertainty (k = 2) better than 250 parts in 10⁶. Experimental data are fitted to a virial type equation, obtaining standard deviations within the uncertainty of the measurements, and the adiabatic coefficient as perfect gas is derived from this fitting. Finally, all these data are compared to GERG-2008 and AGA92-DC equations of state, which are used as reference in the gas industry.

In the present report, density ($\rho$), viscosity ($\eta$), speed of sound ($u$) and refractive index ($n_D$) of ternary liquid mixture containing 1-propanol (1P) (1) + 1,3-diaminopropane (1,3-DAP) (2) + ethyl acetate (EAc) (3) were measured at five different temperatures (T = 298.15 to 318.15 K) and at 0.1 MPa pressure. Data of $\rho$, $\eta$, $u$ and $n_D$ were used to compute the excess molar volume, $V_m^E$, deviation in viscosity, $\Delta \eta$, deviation in ultrasonic speed, $\Delta u$, excess isentropic compressibility, $k_s^E$, excess free volume, $V_f^E$, excess intermolecular free length, $L_f^E$, excess available volume, $V_a^E$, and deviation in refractive index, $\Delta n_D$, and these computed physicochemical properties were fitted to Singh equation. The $V_m^E$ data were fitted to the Nagata and Cibulka equations. Further, Kohler model, Tsao-Smith model, Radojkovic model, Jacob-Fitzner model and Rastogi model were used to calculate the $V_m^E$ values. The speed of sound data was analyzed by various correlations such as Van Dael, Nomato, Impedance dependence, Schaaff’s collision factor theory (CFT) and Jacobson’s free length theory (JFLT). Various correlations like Heller, Arago-Biot, Lorentz-Lorenz, Erying, Newton, Gladstone-Dale, and Weiner were used to correlate $n_D$ data.

The solubilities of 2,4-diaminotoluene (2,4-TDA), methyl 3-amino-4-methyl-N-phenyl carbamate (4-TMC) and dimethyl toluene-2,4-dicarbamate (2,4-TDC) in dimethyl carbonate (DMC) and di(2-ethylhexyl) phthalate (DOP) were determined by dynamic method at 298.15 ∼ 398.15 K under atmospheric pressure. The solubility data were correlated by the modified Apelblat equation, polynomial equation and simplified two-parameter equation. The modified Apelblat equation was more accurate than the others. In addition, the thermodynamic properties of the solution process, including the Gibbs energy, enthalpy and entropy were calculated by the modified Van't Hoff equation. The dissolution process of 2,4-TDC in DOP solvent is a non-spontaneous entropy reduction endothermic process. The dissolution processes of 2,4-TDA, 4-TMC and 2,4-TDC in DMC solvent and 2,4-TDA and 4-TMC in DOP solvent are all non-spontaneous entropy-increasing endothermic processes.

Phase behavior and thermophysical properties of biodiesel at high pressure and high temperature are limited in the literature. These are useful to develop models and to understand their behavior having in mind the use of biodiesel in engines. Liquid to solid phase transitions, by using a vibrating tube densimeter, along with densities of three beef tallow fatty acid alkyl esters were studied in this work. Measurements of the oscillating period for each biofuel were carried out in a modular array constituted by two vibrating tube densimeters coupled in series and connected to a single loading cell. The oscillating period was converted to density by the forced path mechanical calibration (FPMC) method. Experimental liquid density sets for three beef tallow biodiesel samples based on fatty acid alkyl esters (FAAEs) are reported for the first time for pressures up to 137 MPa. These biofuels, named fatty acid methyl esters (FAMEs), fatty acid ethyl esters (FAEEs) and fatty acid butyl esters (FABEs), were measured in the temperature range of 286–393 K. The detection procedure for the beginning of the high-pressure solidification was focused on the beef tallow FABEs sample based upon its lower cloud point (CP_FABEs = 281.15 K) in comparison with the reported property for the other esters (CP_FAEEs = 289.15 K, CP_FAMEs = 291 K) with the same feedstock; therefore, the conditions for the metastable liquid to solid phase transition associated to the effect of high pressure was detailed for waste beef tallow butyl ester biodiesel by performing step-by-step compressions in the interval of 286.20–298.13 K and with the help of the vibrating tube densimeters. FABEs had the lower density in contrast with FAEEs and FAMEs, this one being the denser biofuel. Modeling of liquid density data was performed by the perturbed-chain statistical associating fluid theory (PC-SAFT) Equation of State and the Tammann-Tait equation with maximum absolute average deviations of 0.15 % and 0.05 %, respectively. Both models were applied for correlating the thermodynamic derived properties of the fluid phase: isobaric thermal expansivity and isothermal compressibility.

This study aimed to investigate the perphenazine (form I)’s solubility in three binary solvent systems: acetone + water, n-propanol + water, and N,N-dimethylformamide (DMF) + water, within the temperature range of 278.15 K to 318.15 K. The solubility data were obtained using a dynamic method and fitted using four models: the NRTL model, modified Apelblat equation, CNIBS/R-K model, and Jouyban-Acree model. All four models provided satisfactory fitting results, with the CNIBS/R-K model exhibiting the best performance. In all cases, it was observed that the solubility of perphenazine (form I) exhibited a positive correlation with temperature while keeping the solvent composition constant. Specifically, in the DMF + water binary solvent system, the solubility of perphenazine (form I) increased with higher mass fractions of the positive solvent. Additionally, the phenomenon of co-solvency was observed when perphenazine (form I) was dissolved in the acetone + water and n-propanol + water binary solvent systems. To gain insights into the intermolecular interactions within the perphenazine (form I) crystal, Hirshfeld surface (HS) analysis was employed. The Dmol3 module was used to calculate the electrostatic potential of perphenazine molecules, followed by molecular dynamics simulation, analysis of the solute–solvent and solvent–solvent radial distribution functions (RDF), and calculation of solvation free energy. Overall, this study enhances the understanding of the dissolution behavior of perphenazine (form I) and provides valuable data to support further investigations into its crystallization process.

New compressed liquid densities (ρ) of thiophene + heptane and thiophene + octane are reported in the temperature range from (313 to 363) K, with pressure up to 25 MPa. The compositions are x(1) = 0.1049, 0.2471, 0.5097, 0.7494, and 0.8994 for thiophene (1) + heptane (2), and x(1) = 0.1042, 0.2530, 0.5037, 0.7516, and 0.8988 for thiophene (1) + octane (2). The experimental system uses a vibrating tube densimeter (VTD) and three calibration methods (the first uses hexane and water, the second uses nitrogen and water, and the third uses water and applying vacuum to the VTD as calibration reference fluids). The reported density data are determined using the third method, which notifies the lowest uncertainty and estimates a maximum relative expanded uncertainty ($k=2$) of 0.21 % in the temperature range from (313 to 363) K and pressures up to 25 MPa. The pure compound densities were calculated from previous density measurements represented by the Pimentel-Galicia model. This empirical correlation of the pure compounds was used before for the excess molar volume calculation. The experimental data of the mixtures reported in this work were modeled by the Pimentel-Galicia model at each composition with deviations not higher than 0.07 %. The combined standard uncertainty for composition (considering the purities of the samples) is $u_c\left(x\right)=$ 0.0026. Finally, the isothermal compressibility and isobaric thermal expansivity were evaluated from density data.

This research work reports the cilostazol (form A) dissolution in (ethylene glycol / ethanol + water) mixtures. The co-solvency phenomenon only occurs in mixture of ethanol + water, the maximum solubility in mole fraction is 3.034 × 10^-3 at the composition of 0.85. It was found that the solvation performance of cilostazol in two mixtures mainly depend on the ability of forming hydrogen bond (H-bond) of the solutions and van der Waals interaction. According to the preferential solvation results, it is conjecturable that cilostazol molecules are preferentially solvated by water in water-rich regions. With the increase of alcohol concentration, the destruction of water molecular ordered structure by alcohol through hydrogen bond, and solute molecules are preferentially solvated by ethanol and EG. Nonetheless, when 0.86 < x₁ < 1 in mixture of ethanol + water, solute molecules are preferentially solvated by water again. The calculation of radial distribution function (RDF) between the atoms of H and O for ethanol and the atoms of N and H for solute is to achieve the interaction of the solute and solvents. The correlation fitting was performed for the solubility data through Jouyban Acree model and its derivative models, and the statistical analysis showed that the Apelblat-Jouyban Acree model is more suitable to present the solubility correlation. Meanwhile, the values of apparent molar standard dissolution enthalpy ($\Delta H_{\text{sol}}^{\text{o}}$) and apparent molar standard dissolution entropy ($\Delta S_{\text{sol}}^{\text{o}}$) are positive in each solvents, which reveals that the dissolution process of cilostazol form A is endothermic and entropy favorable within the given temperature range.

In order to separate n-hexane/ethyl acetate (EA) produced in industrial production, the liquid–liquid extraction was used to separate the azeotropic system with sulfolane, 1,2-propanediol and dimethyl sulfoxide (DMSO) as extractants. The liquid–liquid equilibrium (LLE) data of the n-hexane + EA + sulfolane/1,2-propanediol/DMSO were measured at 303.15 K, 313.15 K and 323.15 K. The extraction capacity of the extractants were evaluated by the distribution coefficient (D) and separation factor (S). The LLE data were correlated using the NRTL and UNIQUAC thermodynamic models to obtain binary interaction parameters. The root mean square deviation (RMSD) were all less than 0.02 indicating that the two models were suitable for the phase equilibrium behavior. GUI-MATLAB software was used to test the reliability of the regressed binary interaction parameters. The Dmol³ module of the Materials Studio was used to analyze σ-profile of n-hexane, EA and extractants and to assess the interaction energy between the components. The results show that sulfolane is the best extractant for the separation of n-hexane + EA.

We measured the densities and viscosities of two ionic liquids, triethyl(methoxymethyl)phosphonium bis(trifluoromethanesulfonyl)amide ([P_222(1O1)][TFSA]) and triethyl(2-methoxyethyl)phosphonium bis(trifluoromethanesulfonyl)amide ([P_222(2O1)][TFSA]), at atmospheric pressure and 273.15–363.15 K. The high-pressure density at the pressures up to 50 MPa was also measured at 298.15–353.15 K. Meanwhile, CO₂ solubility in these phosphonium-based ionic liquids was determined using a magnetic suspension balance at 303.15–333.15 K and pressures up to 6 MPa. The experimental density and viscosity at atmospheric pressure were fitted using quadratic and Vogel-Fulcher-Tammann equations, respectively. The high-pressure density was fitted using the Tait equation and Sanchez-Lacombe equation of state. The properties of the two ether-functionalized ionic liquids were compared to those of triethylpentylphosphonium bis(trifluoromethanesulfonyl)amide [P₂₂₂₅][TFSA]. The density at atmospheric pressure increased in the order [P₂₂₂₅][TFSA] < [P_222(2O1)][TFSA] < [P_222(1O1)][TFSA]. The introduction of the ether group effectively reduced viscosity in the following order: [P_222(1O1)][TFSA] < [P_222(2O1)][TFSA] < [P₂₂₂₅][TFSA]. The CO₂ solubilities in [P_222(1O1)][TFSA] and [P_222(2O1)][TFSA] were slightly lower than those in [P₂₂₂₅][TFSA]. In contrast, the molality of CO₂ (m₁) increased in the order [P₂₂₂₅][TFSA] < [P_222(2O1)][TFSA] < [P_222(1O1)][TFSA]. Ether functionalized phosphonium-based cations are effective in enhancing the physical absorption of CO₂, particularly the molality of CO₂.