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Abstract The Solubility, density and refractive index of the formamide(FA)/ N -methylformamide(NMF)/ N , N -dimethylformamide(DMF) + rubidim bromide/cesium bromide+ water ternary systems were determined at (283.15, 298.15 and 313.15) K. The solubility of the RbBr and CsBr decrease significantly when adding amides into the aqueous solution. The variation trend of density is consistent with solubility, and the change of the refractive index is different. The isothermal experimental solubility was correlated by the NRTL model and the UNIQUAC model. The isothermal solubility, density and refractive index of the ternary systems were fitted by the four parameter equation. Moreover, the mean activity coefficients of the FA/NMF/DMF + RbBr/CsBr + H 2 O systems at experimental temperatures were obtained through the UNIQUAC model. Besides, to investigate the temperature effect on the solid-liquid equilibrium, the multiple temperatures solubility was fitted by the modified Apelbl at equation and the λh equation. Graphical abstract The phase behavior of FA/NMF/DMF (1) + RbBr/CsBr(2) + H 2 O (3) systems were investigated at 283.15, 298.15 and 313.15K. Unlabelled Image Highlights • FA/NMF/DMF + RbBr/CsBr + H 2 O ternary systems were investigated. • Solubility, density and refractive index of SLE systems were determined. • The mean activity coefficients of the systems were obtained by the UNIQUAC model. [ABSTRACT FROM AUTHOR]

The (solid + liquid) phase equilibrium of the ternary system (NaCl + RbCl + H 2 O) at T = (288.15, 298.15 and 308.15) K was studied by the method of isothermal solution saturation. Moreover, the density and refractive index of the solution was also determined. The solid phase was studied by the Schreinemaker’s wet residue method and verified by X-ray diffraction. The results show that each of the phase diagrams contains one invariant point, two univariant curves, and three crystallization regions. The crystallization region of NaCl increased obviously with the temperature increasing, while the crystallization regions of RbCl and the mixed crystallization region of (NaCl + RbCl) decreased a little. Furthermore, there are break points at the invariant points for density and refractive index curves. [ABSTRACT FROM AUTHOR]

[Display omitted] The phase equilibria of Formamide (FA)/ N -Methylformamide (NMF)/ N, N -Dimethylformamide (DMF) + Rb 2 SO 4 + H 2 O ternary system at three temperatures (T = 288.2, 298.2 and 308.2 K) were studied by isothermal dissolution method. The effects of temperature and amide structure on the isothermal solubility, density and refractive index of the system were discussed. • The solid–liquid equilibrium of FA/NMF/DMF + Rb 2 SO 4 + H 2 O was investigated; • The saturated solubility decreases with the increase of amide content; • Higher temperature increases the solubility of Rb 2 SO 4 in mixed solvents; • Multiple factors contribute to the density and refractive index of at different temperatures. In this work, the solid–liquid equilibrium (SLE) of the ternary systems formamide (FA)/ N -methylformamide (NMF)/ N, N -dimethylformamide (DMF) + Rb 2 SO 4 + H 2 O was measured at temperatures of 283.2, 298.2, and 313.2 K. The isothermal solubility of Rb 2 SO 4 in mixed solvents, the density and refractive index of the saturated solutions were determined. At a given temperature, with the increase of the amide content in the mixed solvent, the saturated solubility of Rb 2 SO 4 decreased significantly. The density trend was consistent with the solubility. However, the refractive index increased with increasing the content of amide. The solubility increased with increasing the temperature, whereas, the density curves and refractive index curves at the three temperatures showed a point of intersection. In addition, the influence of the polarity and structure of amide on the solubility of the ternary system was also discussed. Finally, the experimental data were fitted with empirical equations. [ABSTRACT FROM AUTHOR]

The (solid + liquid) equilibrium (SLE) and (liquid + liquid) equilibrium (LLE) of RbCl/CsCl + ethylene carbonate (EC) + H 2 O ternary systems were carefully investigated at 298.15 K. The SLE and LLE data were correlated by the corresponding equations respectively. Furthermore, the thermodynamic properties of RbCl/CsCl in the EC–water systems were determined by potentiometric method at T = 298.15 K. The experiment data were correlated by the Pitzer, modified Pitzer and the extended Debye–Hückel equations. The mean activity coefficients, osmotic coefficients and excess Gibbs free energies, standard Gibbs free energy of transfer and the standard solubility product of systems were calculated. The mean activity coefficient γ ± decreases with the increase of the molality of electrolyte at the fixed mass fraction of EC. But γ ± vary abnormally with the increase of the EC content. The result of Δ G t 0 reflects the spontaneously transfer of the electrolytes from water to the mixed solvents. [ABSTRACT FROM AUTHOR]

The isothermal solubility, density and refractive index of MNO 3 (M = Na, K, Rb, Cs) in imidazole ionic liquid [C n mim]Cl/[C n mim]Br ([C n mim] = 1-alkyl-3-methylimidazolium; n = 2, 4, 6, 8) + H 2 O was measured at 298.15 K under atmospheric pressure. The effects of the ionic liquid structure and the types of inorganic salts on the phase equilibrium property of ternary systems have been discussed in detail. The Jouyban–Acree model is used to correlate and predict solubility, density and refractive index of the investigated systems. Moreover, a simple four-parameter polynomial empirical equation is used to fit the experimental data. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present the results of our study of the phase equilibria for two quaternary systems: water+1-propanol/2-propanol+potassium chloride (KCl)+cesium chloride (CsCl) at 298.1±0.1K. We also produced the binodal curves and tie-lines at different KCl/CsCl mass-fraction ratios, and produced integrated phase diagrams for the quaternary systems. We also discuss the solvation abilities of KCl and CsCl, and the effect of the polarity of the organic solvent on the liquid–liquid equilibrium. We compared the experimental tie-lines derived for the quaternary systems with values predicated by modifying the Eisen–Joffe equation. The model produced satisfactory results. [Copyright &y& Elsevier]

• Rb 2 SO 4 + RbBr + H 2 O and Cs 2 SO 4 + CsBr + H 2 O were selected as the research systems. • Stable solid–liquid equilibrium was investigated and discussed. • One invariant point, two univariant curves, and three crystallization regions are observed. • The refractive index of the saturated were determined and fitted. The phase equilibrium and physic-chemical properties of Rb 2 SO 4 (1)-RbBr(2)-H 2 O(3)/Cs 2 SO 4 (1)-CsBr(2)-H 2 O(3) systems at T = (288.15, 298.15 and 308.15) K were determined by the isothermal solution saturation method. At the three temperatures, the two systems both contain one invariant point, two univariant curves, and three crystallization regions. The Schreinemaker's wet residue method and X-ray powder diffraction method were used to verify the solid phase. The phase diagrams of Rb 2 SO 4 (1)-RbBr(2)-H 2 O(3) and Cs 2 SO 4 (1)-CsBr(2)-H 2 O(3) at the three temperatures show that higher temperature reduces the area of the crystallization region of the salts (RbBr and CsBr). The comparison of the two systems at 298.15 K suggests that the crystallization region area of the salts is strongly affected by the solubility and hydration ability of the salts. The refractive index of these systems reached the maximum at the invariant point. At different temperatures, the refractive index increases with increasing temperatures. The results in this paper may provide useful information for the separation of the salts from aqueous solution. [ABSTRACT FROM AUTHOR]

• MCl + TMU + H 2 O systems (M = Na, K, Rb, Cs; TMU = tetramethylurea). • LLE systems of CsCl + TMU + H 2 O at 298.2 and 308.2 K. • SLE system of CsCl + TMU + H 2 O at 288.2 K. • SLE systems of NaCl/KCl/RbCl + TMU + H 2 O at 288.2, 298.2 and 308.2 K. • Affecting factors of temperature, solubility and solvent properties are discussed. For this article, we investigated the phase behavior and physicochemical properties of the ternary systems MCl (M = Na, K, Rb, Cs) + tetramethylurea (TMU) + H 2 O at temperatures of 288.2, 298.2 and 308.2 K. For (solid–liquid) equilibrium (SLE) systems (NaCl/KCl/RbCl + TMU + H 2 O at three temperatures and CsCl + TMU + H 2 O at 288.2 K), the density, solubility and refractive index about the saturated solutions was obtained. About (liquid–liquid) equilibrium (LLE) systems (CsCl + TMU + H 2 O at 298.2 and 308.2 K), the binodal curves and tie lines were obtained. The three parameter equation, Othmer-Tobias and Bancroft equations were used to correlate the SLE and LLE data. [ABSTRACT FROM AUTHOR]