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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]

• 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]