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Solid–liquid-phase equilibrium is an important part of chemical thermodynamics, and its basic theoretical research plays a vital role in the advancement of the chemical industry. Solid–liquid equilibria for binary mixtures of 3-nitrotoluene and 4-nitrotoluene were measured using differential scanning calorimetry under atmospheric pressure (101.3 kPa). The results showed that the phase diagram of the 3-nitrotoluene + 4-nitrotoluene binary system presented a eutectic behavior, and the eutectic point was x1 = 0.6487, TE = 272.15 K. Furthermore, the experimental results were correlated with Wilson and nonrandom two-liquid (NRTL) activity coefficient models well. The relative standard deviations were 0.496 and 0.236, respectively, and the absolute mean deviations were 0.005 and 0.001, respectively. [ABSTRACT FROM AUTHOR]

The solid-liquid phase equilibrium for binary system of 2,4,6-trimethylphenol (TMP) and 2,5-dimethylphenol (DMP) was built by differential scanning calorimeter under atmospheric pressure (101.3 kPa). Two thermodynamic models of Wilson and NRTL were employed to correlate and calculate the experimental data for the system. The mean-root-square error values are 0.1924 and 0.2204. The residual sums of square values are 0.4810 and 0.6315, respectively. Values R2 are all larger than 0.9995. The pure TMP, pure DMP and the mixture of them were confirmed by gas chromatography, Raman spectrometer and X-ray diffraction before and after the determination. In addition, the specific heat (Cp) of solid TMP and DMP between 285.15 and 335.15 K and liquid TMP and DMP between 353.15 and 403.15 K were determined at atmospheric pressure. [ABSTRACT FROM AUTHOR]

Solid-liquid equilibrium (SLE) of Na + //Cl − , NO 3 − , SO 4 2− -H 2 O quaternary system at 373.15 K was determined via isothermal solubility equilibrium method. The dry-salt phase diagram and the tri-prism stereogram of this system were obtained found on the solubility data. Without any solid solutions or double salts, the phase diagram is the simplest one of the quaternary system, consisting of one invariant point, three univariant curves, three crystallization fields of single salts, three cocrystallization fields for two salts and one cocrystallization field for three salts. At the same time, the physicochemical properties (density and conductivity) of this system were measured in the experiment. Moreover, comparing with the equilibrium phase diagrams in the temperature range from 258.15 K to 373.15 K, it could be found that the crystallization field of the double salt D (NaNO 3 .Na 2 SO 4 .10H 2 O) reduces with the temperature increases, and disappears at 373.15 K. With the growing temperature, the crystallization field of Na 2 SO 4 enlarges while the crystallization fields of NaNO 3 and NaCl both reduce. All above the experimental results obtained can be applied to solve the salt separation of the relative brine system mainly containing the four aforementioned ions as well as conduct further theoretical studies. [ABSTRACT FROM AUTHOR]

• Solubility of 2′,4′-dichloro-5′-fluoroacetophenone increases with increasing the chain length of esters solvent. • Contribution of entropy and enthalpy change tends to be equal with increasing temperature. • The interactions of Cl⋯H, O⋯H, and F⋯H dominate molecular interaction in crystal. 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. [ABSTRACT FROM AUTHOR]

• Solid-liquid phase equilibrium of NH 4 + //SO 4 2−, H 2 PO 4 −–H 2 O system aiming at salt-containing wastewater treatment in lithium-ion batteries industry. • Constructing the Pitzer thermodynamic model of the ternary system. • Calculating solubilities of the ternary system being in good agreement with the experimental results. A tremendous amount of wastewater containing ammonium salts, mainly NH 4 H 2 PO 4 and (NH 4) 2 SO 4 , has been produced in the production of cathode material of lithium iron phosphate (LFP). However, as an important basis for salt separation, the solid–liquid phase equilibrium (SLPE) of these two salts has been investigated by few studies. In this study, SLPE of the ternary system (NH 4 + //SO 4 2−, H 2 PO 4 −–H 2 O) from 313.15 K to 343.15 K at 101.2 kPa were investigated by isothermal dissolution method, and the corresponding physicochemical properties (density, viscosity, and pH) of saturated solution were measured. The phase diagram is composed of one invariant point, two univariant curves, and two single-salt crystallization fields for NH 4 H 2 PO 4 and (NH 4) 2 SO 4. Comparing the phase diagrams from 263.15 K to 343.15 K, it is obvious that two single-salt crystallization fields shrink with increasing temperature. And the area reduction of NH 4 H 2 PO 4 in two salts is more significant. When the temperature drops below 268.15 K, the ice crystallization field would appear. Neither single-salt solid solution, hydrous salt nor double salt was found in the whole temperature range. Furthermore, Pitzer model was successfully applied to describe the SLPE of the ternary system at temperatures from 273.15 K to 343.15 K. The lacking Pitzer-model parameters of mixed electrolytes (θ SO4-H2PO4 and ψ NH4-SO4-H2PO4) were calculated, and the temperature coefficients of model parameters and dissolution equilibrium constant were obtained. The importance of this study is that it supplies basic data and theoretical references for the separation and resource utilization of two ammonium salts from wastewater in the LFP batteries industry. [ABSTRACT FROM AUTHOR]

• Lower polarity and stronger hydrophobicity leading to lower solubility of EVA. • The relative contribution of enthalpy decreases with increasing n -propanol content. • LLPS is mainly dependent on solute and solvent properties but not temperature. • EVA is more prone to LLPS due to greater steric hindrance and hydrophobicity. • Water and oil phase satisfies optimal and suboptimal stable ratio, respectively. How different solute affects solid-liquid equilibrium and the underlying mechanisms of how solutes are partitioned in the liquid-liquid two phases during crystallization are not well understood, which setting up obstacles to better control of the crystallization and purification process. Thus, firstly, we uncover how the solvent composition and solute structure affect the phase equilibrium of vanillin (VA) and ethyl vanillin (EVA) in n -propanol-water mixed solvent. The results show that both the solubility of VA and EVA show significant co-solvency phenomenon. Besides, stronger hydrophobicity of EVA leading to lower solubility than that of VA. Furthermore, we found that the ratio of relative contribution of enthalpy and entropy decreases with increasing n -propanol content. Secondly, ternary phase diagrams indicate that EVA is more prone to liquid-liquid phase separation (LLPS) than VA, since EVA possesses greater steric hindrance and stronger hydrophobicity. Interestingly, the LLPS curves are mainly dependent on solute and solvent properties but almost independent of temperature in both systems. Meanwhile, the tie lines are found to be not strictly parallel to each other, which suggest that solute clusters exist in the lean solute phase satisfying the optimal stable ratio and the rich solute phase satisfying the suboptimal stable ratio. Finally, molecular simulation showed that the energy of the LLPS system is always lower than that of the homogeneous solution system. These contributions provide in-depth understanding of the solid-liquid and liquid-liquid phase behavior, which is expected to provide theoretical guidance for breaking through the bottleneck of crystallization control. [ABSTRACT FROM AUTHOR]

• The dissolution thermodynamic properties of hydroxylamine sulfate in water-ethanol were studied for the first time. • The experimental solubility data of hydroxylamine sulfate were calculated by four different thermodynamic models. • The factors affecting liquid-liquid phase separation were studied by ternary phase diagram. • The nucleation of hydroxylamine sulfate in water-ethanol-hydroxylamine sulfate occurred in the aqueous phase instead of oil droplets. • The study provides basic data for the study of the crystallization process of hydroxylamine sulfate. The thermodynamic properties of hydroxylamine sulfate (HAS) in binary mixed solvents of water-ethanol were investigated in this work. Experimental results indicated that a temperature above 323.15 K will bring about the occurrence of liquid-liquid phase separation in the water-ethanol-HAS system. Solubility of HAS in water and ethanol-water binary mixed solvents was experimentally determined from 283.15 to 323.15 K under atmospheric pressure (101.3 kPa) by employing a gravimetric method. As the mass fraction of water in the mixed solvent increase, there is an increase in the solubility of HAS. In addition, the solubility of HAS is positively dependent on the temperature. Furthermore, the modified van't Hoff model, Apelblat model, van't Hoff − Jouyban − Acree model, and Apelblat − Jouyban − Acree model were used to correlate the experimental solubility of HAS, and the Apelblat model showed the best agreement. Besides, the van't Hoff equation was utilized to evaluate the thermodynamic parameters of HAS in binary solvents, calculation results confirm that these dissolving processes are endothermic and entropy-driving. Ternary phase diagrams with liquid-liquid equilibrium at 324.15, 328.15 and 333.15 K were constructed, and the boundaries of each phase area of the ternary phase diagram were verified at 333.15 K. As for the water-ethanol-HAS system, the temperature has an influence on the phase zone of the ternary phase diagram by affecting solid-liquid phase equilibrium. However, the temperature has no effect on the liquid-liquid phase equilibrium. The nucleation process of oiling-out crystallization of HAS was determined to follow a two-step mechanism: the liquid-liquid phase separation is generated at first, and then nucleation occurred and crystals subsequently grow in the aqueous phase. [ABSTRACT FROM AUTHOR]

• The effect of solvent properties on the solid–liquid equilibrium of 2-bromodibenzofuran was investigated for the first time. • The solubility in alcohol solvents is determined by the solvent hydrogen bond donor tendency and the cohesive energy density. • Solubility in non-alcoholic solvents is affected by solvent polarity, donor tendency and cohesive energy density. • The dissolution thermodynamic properties were calculated to reveal the thermodynamic behavior. The effects of solvent properties and temperature on the solid–liquid equilibrium of 2-bromodibenzofuran (NSC 1735) were investigated for the first time in terms of temperature, solvent polarity, hydrogen bonding donor and acceptor tendency, as well as cohesive energy density. Firstly, the equilibrium solubility of 2-bromodibenzofuran in 12 mono-solvents, such as alcohol, ketone, nitrile and ester, was determined by gravimetric method ranging from 278.15 ∼ 343.15 K. The values of the mole fraction solubility of NSC 1735 in all the selected solvents increased with increasing temperature. Moreover, the statistical correlations between temperature and solubility were described by the modified Apelblat equation, λh equation, Van't Hoff equation, and NRTL model. The calculated ARD% values show that the correlation results agree well with the experimental date and the modified Apelblat equation receives the best regression performance. Solvent polarity and cohesive energy density mainly determine the solubility of NSC 1735 in various solvents. Thermodynamic studies of dissolution have shown that the dissolution of NSC 1735 in selected solvents.is endothermic and enthalpy driven. The change of dissolution enthalpy is the main contributor to the molar Gibbs free energy during the dissolution process. [ABSTRACT FROM AUTHOR]

• The solid-liquid binary phase diagram of tetramethylbiphenyl isomers were determined. • We discuss effect of temperature and low melting component on the melting mechanism. • The mixing thermodynamic properties were calculated to discuss the phase behavior. • Enthalpy-entropy compensation analysis uncover different dissolution mechanism. Three binary molten phase diagrams of three isomers of tetramethyl biphenyl (TMB) were constructed by differential scanning calorimetry (DSC) at 101.3 kPa. Our results reveal that the tetramethyl biphenyl isomers binary system presents a eutectic behaviour that lays a solid foundation for its separation technology. Meanwhile, the thermodynamic model such as Wilson, NRTL and Ideal model were employed to correlate the phase equilibrium data of the tetramethyl biphenyl isomers. The results show the ideal model can describe two binary phase behaviour of 2,2′,3,3′-Tetramethyl biphenyl (TMB1) + 3,3′,4,4′-Tetramethyl biphenyl (TMB3) well while it isn't suitable for TMB1 + 2,3′,3,4′-Tetramethyl biphenyl (TMB2) and TMB3 + TMB2 systems. The best correlation of the solid–liquid equilibrium data has been obtained by the NRTL equation. Besides, the mixing thermodynamic properties were calculated by NRTL model to gain more insights into the phase behaviour of the binary melt eutectic systems. Then, we discuss the co-effect of temperature and low melting point components on the binary phase melting mechanism. At last, non-linear enthalpy–entropy compensation analysis indicated different dissolution mechanism with the variation in mixtures composition. [ABSTRACT FROM AUTHOR]