Journal of Chemical & Engineering Data最新文献

Supercritical water’s unique properties enable organic decomposition and inorganic synthesis, but salt precipitation risks clogging. This study investigates the solubility, supersolubility, and metastable zone width (MSZW) of type 1 and type 2 salts using salt bed dissolution (cooling) and precipitation (warming) methods. At supercritical conditions (25 ± 0.1 MPa), type 1 salts show a moderate solubility decline (1–2 orders of magnitude, to ∼10^–1 to 10° mmol·kg^–1), while Type 2 salts exhibit a drastic drop (3–4 orders, to ∼10^–3 to 10^–2 mmol·kg^–1). Type 1a salts display a wide metastable zone between the critical point and three-phase equilibrium, whereas type 1b salts show stable MSZW. Type 2a and 2b salts exhibit minimal dissolution differences. Most salts (except type 1a) have a wider MSZW under transcritical conditions but are narrower under supercritical conditions. These findings clarify salt-specific precipitation behaviors, aiding in clogging prediction and mitigation strategies for supercritical water processes.

n-Propanol and monoethanolamine are widely used organic solvents and reaction media in the chemical industry. This work reports rigorous thermodynamic data, including density, speed of sound, and refractive index for the binary n-propanol + monoethanolamine system at 0.1 MPa and temperatures ranging from 293.15 to 318.15 K. Excess properties, such as excess molar volume, excess speed of sound, excess isentropic compressibility, and excess refractive index, were calculated to elucidate the system’s thermodynamic behavior and the nature of intermolecular interactions. Molecular dynamics simulations and quantum mechanical calculations combined with ¹H NMR and IR spectra reveal that complex hydrogen bonding between the hydroxyl group of n-propanol and the amino/hydroxyl groups of monoethanolamine, coupled with van der Waals forces, drives significant nonideal behavior in the mixture. This study provides reliable thermodynamic data and theoretical insights for optimizing solvent formulations, chemical processes, and design strategies involving n-propanol and monoethanolamine, thereby facilitating technological advancements in related fields.

In the study, the experiment solubility of difenidol hydrochloride was determined in 12 neat solvents [water, methanol, ethanol, n-propanol, n-butanol, 1-pentanol, N-methyl-2-pyrrolidone(NMP), N,N-dimethylformamide(DMF), N,N-dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), acetonitrile (MeCN), and acetic acid] at a temperature range from 278.15 to 323.15 K by a gravimetric method under 0.1 MPa. Results indicated that the experimental mole fraction solubility (10x) order of difenidol hydrochloride in 12 neat solvents at the temperature 298.15 K was: methanol(0.1771)>DMSO(0.1343)>NMP(0.0725)>acetic acid (0.0601)>DMF(0.0467)>DMA(0.0357)>ethanol (0.0336)>n-propanol (0.0255)>n-butanol (0.0137)≈water (0.0135)>1-pentanol (0.0098)>MeCN (0.0041), and solubility increased with the increase in temperature. Three models, including Modified Apelblat model, Van’ t Hoff model, and Yaws model, were applied to correlate the experimental data and analyze the solubility data of difenidol hydrochloride. Based on the principle of similar compatibility, the law of solubility and miscibility of difenidol hydrochloride in selected solvents was discussed according to Hansen solubility parameters (HSP) and solvent effect for predicting solubility behavior.

The hydration behavior of glycine and L-leucine was examined in aqueous solutions of calcium lactate. The experiments were accomplished at atmospheric pressure across a temperature range from 293.15 to 318.15 K, emphasizing the nature of solute–solvent interactions. The volumetric properties were estimated by employing experimentally measured density and speed of sound results. The interactions between leucine or glycine and calcium lactate were analyzed by using the values of apparent molar volume, apparent molar isentropic compressibility, infinite dilution partial molar volume, and volume of transfer. The volumetric transfer parameters were determined and analyzed using the cosphere overlap model. Among all of the interactions present in the system, hydrophilic interactions were found to be the most dominant. These interactions were more pronounced in the case of glycine compared to leucine. The positive contribution to the volume may be attributed to the interaction between calcium ions and the carbonyl or amino groups of the amino acids. Additionally, the hydrophobic lactate group of calcium lactate may engage in hydrophobic interactions with the nonpolar regions of the amino acids in aqueous solution. However, the hydrophilic interactions significantly outweigh the hydrophobic contributions.

The present study investigates the influence of dissolved gases on the liquid viscosity η_L and interfacial tension σ of linear and branched alkanes under saturated conditions by using surface light scattering (SLS). Five binary mixtures consisting of n-pentane, n-decane, n-hexadecane, or 2,6,10,15,19,23-hexamethyltetracosane (squalane) with dissolved propane or carbon dioxide are studied at temperatures T between 255.7 and 423.15 K, pressures p up to 7.8 MPa, and solute amount fractions up to 0.79. Using SLS, η_L and σ were determined with an average expanded experimental uncertainty (coverage factor k = 2) of 2.0%. Polarization-difference Raman spectroscopy was simultaneously applied to SLS experiments to determine the liquid-phase composition. The influence of the dissolved gas is discussed by comparing the thermophysical properties of the mixtures to those of the pure solvents. It could be observed that the molecular characteristics of the solute have a minimal influence on η_L of the mixture, which is primarily determined by the solvent’s characteristics. In contrast, the molecular characteristics of the solvent and solute strongly influence σ. Overall, the results of this study contribute to expanding the database for η_L and σ for binary mixtures, which can be considered surrogate mixtures for refrigeration oil–refrigerant systems.

This study demonstrates the applicability of different experimental techniques in combination with equilibrium molecular dynamics (EMD) simulations for investigating the influence of hydrogen (H₂) on various thermophysical properties of n-hexane at temperatures T from (298 to 473) K and pressures p from (0.1 to 20) MPa at or close to vapor-liquid equilibrium. The amount fraction of H₂ in the liquid phase, x_H2, and the liquid density ρ are determined via the isochoric saturation method and vibrating-tube densimetry. Polarization-difference Raman spectroscopy (PDRS) serves to characterize x_H2 during dynamic light scattering (DLS) experiments allowing access to the thermal diffusivity a and the Fick diffusion coefficient D₁₁ in the liquid phase as well as surface light scattering (SLS) experiments used to determine the liquid dynamic viscosity η and the vapor-liquid interfacial tension σ. With increasing p and x_H2, the measurement results for a and D₁₁ are not significantly affected, except for states approaching the critical point. The experimental data for ρ, η, and σ show decreasing values with increasing x_H2. The EMD simulations predict the influence of H₂ on D₁₁, η, σ, and ρ well, and allow to discuss the behavior of D₁₁ and σ in connection with the fluid structure.

In this study, the solubility of cefotaxime sodium (CTX) in two new ternary systems of “water+methanol(MeOH)+isopropanol(IPA)” and “water+MeOH+ethyl acetate(EA)” at various temperatures was determined and represented using the CNIBS/Redlich–Kister model. In the first ternary system, the mean relative deviation percentages (MRDs%) were 2.6, 6.6, 6.1, and 6.2% for the CTX solubility at temperatures of 278.2, 283.2, 288.2, and 293.2 K, respectively. The MRDs% were 5.9, 7.2, 7.8, and 8.9% for the CTX solubility in the second system. It was concluded that the model used adequately predicted the CTX solubility in two new ternary systems. In addition, the apparent thermodynamic properties of the dissolution process indicated that the CTX dissolution process is endothermic and enthalpy-driven. Furthermore, the solvent amounts for crystallization processes in two ternary systems were optimized based on the obtained solubility model, and the overall MRDs% between the experimental and predicted yields in two systems were 4.0 and 6.7% at 278.2 K. The solvent amounts of the crystallization process were effectively optimized based on the predictions of reliable solubility models. Finally, the solid powders of CTX from two optimized crystallization systems were analyzed by powder X-ray diffraction (XRD), particle size detector (PSD), and scanning electron microscopy (SEM).

Toluene is a valuable chemical used in various industrial applications, making its purification a critical process. Removing aliphatic hydrocarbons, such as dimethylcyclohexanes, is one of the main challenges in producing high-purity toluene; however, the thermodynamic properties of mixtures containing dimethylcyclohexanes and toluene remain largely undocumented in the literature. Therefore, this work focuses on studying the equilibrium behavior of two of its isomers in mixtures with toluene. The vapor–liquid equilibria of binary mixtures of cis- and trans-1,4-dimethylcyclohexane with toluene were measured at 15, 25, and 40 kPa across the full range of molar fractions. The thermodynamic consistency of the obtained data was verified using the Van Ness method modified by Fredenslund, as well as the Van Ness point-to-point test and the Herington test. The behavior of the systems was described by using the NRTL and UNIQUAC models. For the mixture of toluene with trans-1,4-dimethylcyclohexane, experimental data and both models confirm the existence of a minimum-boiling azeotrope; however, the mixture of toluene with cis-1,4-dimethylcyclohexane does not exhibit azeotropic behavior. The resulting models will be helpful in process simulations, which is crucial in the toluene production process.

For the binary mixture (1,4-dioxane (1) + chloroform (2)), the refractive index (n_D) was measured at temperatures T = (295.15, 298.15, 301.15, 304.15, 307.15, 310.15, and 313.15) K and at atmospheric pressure over the whole composition range. The molar refraction (R_m), reduced molar free volumes (V_m/R_m), molecular radius (r), internal pressure(P_int), and their excess properties were calculated from experimental data. These values were then analyzed to determine the type and nature of specific intermolecular interactions among the components. The refractive indices of the binary mixture were calculated using nine different mixing rules (Gladstone–Dale, Arago–Biot, Weiner, Heller, Lorentz–Lorentz, Eykmen, Eyring–John, Oster, and Newton), and the results were compared with experimental measurements at each temperature. The nature of the molecular interactions was explored by analyzing the thermodynamic properties, specifically by fitting the excess parameters to the Redlich–Kister polynomial equation to derive the corresponding coefficients and standard errors.

In this work, a static analysis method was used to measure the solubility of nine compounds: C1 and C2 in three solvents, C3 in four solvents, and C4–C7 in four pure solvents, with temperatures ranging from 268.15 to 328.15 K (measurements in p-xylene were performed over the temperature interval of 288.15 to 328.15 K, whereas for other systems, the experimental temperature range was maintained between 268.15 and 308.15 K). Experimental results demonstrate enhanced solubility for all compounds at selected temperatures. Solubility data were correlated using seven thermodynamic models: Yaws, polynomial, van’t Hoff, λh, Wilson, NRTL, and UNIQUAC, yielding superior fits characterized by an average absolute relative deviation (ARD) below 5% and root-mean-square deviation (RMSD) under 0.2%. Among these, the polynomial model exhibited optimal performance for empirical correlations, whereas the NRTL model provided the best fit among activity coefficient models. Solvent-dependent solubility variations were further elucidated through Hansen solubility parameters. Thermodynamic calculations confirmed dissolution to be endothermic and entropy-driven in most systems. The measured solubility and fusion enthalpy data establish fundamental references for optimizing homogeneous catalysis and crystallization processes of organic aluminum compounds.