Solubilities, Densities, and Refractive Indices of the Ternary Systems KCl + RbCl + H₂O and KCl + MgCl₂ + H₂O at 348.15 K

Abstract

The solubilities of electrolyte mixtures ternary systems KCl + RbCl + H2O and KCl + MgCl2 + H2O at 348.15 K were obtained by isothermal evaporation method. The corresponding physicochemical properties of the solution such as density and refractive index were also determined. The Scherinemakers’ wet residue method was used to determine the composition of the solid phase. The metastable phase diagram, density versus composition diagram, and refractive index versus composition diagram were constructed on the basis of the experimental data. Results showed that these two ternary systems were both complex type. The incommensurare double salt carnallite (KCl·MgCl2·6H2O) was found in the KCl + MgCl2+ H2O system at 348.15 K. Comparisons between the metastable phase diagrams of KCl + MgCl2+ H2O system at (298.15, 323.15, and 348.15) K show that the crystallization zone of carnallite decreases with the increase in temperature. The solid solution [(K,Rb)Cl] was formed in the KCl + RbCl + H2O system at 348.15 K. Comparisons between the metastable phase diagrams of KCl + RbCl + H2O system at (298.15, 323.15, and 348.15) K show that the crystallization zone of [(K,Rb)Cl] decreases with the increase in temperature. The empirical equation was used to calculate the refractive indices of the equilibrated solution. The calculated results keep in line with experimental values with the maximum relative error less than 0.005.

Experimental Data and Modeling of Solution Density and Heat Capacity in the Na–K–Ca–Mg–Cl–H2O System up to 353.15 K and 5 mol·kg–1 Ionic Strength

“…The relative error and standard deviations obtained are reported in Table 9 for the heat capacity and Table 10 for the density. The maximum deviation is obtained with the study of Yu et al 75 However, in the MgCl 2 −H 2 O binary system, Yu et al measured a density value higher than those of other studies (Figure 12). The same observation can be made on the study of Deng et al (Figure 10).…”

“…Density ρ of MgCl 2 solutions as a function of the concentration at (a) T = 273.15 K, (b) T = 303.15 K, (c) T = 348.15 K, and (d) T = 368.15 K. ○, ref ; ▲, ref ; ×, ref ; , model.…”

“…To do this, the various ternary subsystems were studied using experimental data provided by the literature. Saluja et al measured the heat capacity of the Na–Ca–Cl, Na–Mg–Cl, and Ca–Mg–Cl ternary systems between T = (298.15 and 373.15) K. For density, the compilation of Laliberté and the data of Kumar, Zezin et al, , Qiblawey et al, , Deng et al, Yu et al , and Badarayani et al were used. First, the calculations were performed with PhreeSCALE using only the binary interaction parameters.…”

Salt–Water Phase Equilibria in Ternary Systems K+(Mg2+), NH4+//Cl––H2O at T = 273 K

“…There is a wide range of saline lakes and oilfield brine spread in the Qinghai, Xinjiang, Tibet, and Inner Mongolia provinces in China . To scientifically exploit brine resources, the relevant phase equilibria and phase diagram focused on the composition of those brines are necessary. − According to the composition characteristics (high content sodium, magnesium, potassium, ammonium, calcium, chloride, and borate) of oil field brine in Nanyishan, the seven-component system Na + , K + , NH 4 + , Ca 2+ , Mg 2+ //Cl – , and borate–H 2 O can be applicable to represent the phase equilibrium relationship of the brine…”

The Stable Phase Equilibria of the Ternary Systems Na2SO4 + Rb2SO4 (Cs2SO4) + H2O at 298.2 K

“…Phase equilibrium studies provide the requisite theoretical and practical importance for the comprehensive utilization of salt lake brines . Plenty of studies about phase equilibrium data and phase diagrams have been performed to utilize salt lake brines or underground brines. , A series of ternary, quaternary, and quinary aqueous systems containing rubidium have been investigated in our previous work at (298–348) K. Results show that the double salt RbCl·MgCl 2 ·6H 2 O was formed in chloride systems containing rubidium and magnesium, and the continuous solid solution [(K, Rb)­Cl] was found in chloride systems containing potassium and rubidium. − In the saturated solution of borate systems containing rubidium, the crystallographic form for rubidium borate is RbB 5 O 6 (OH) 4 ·2H 2 O. − So far, previous phase equilibria studies of cesium containing systems mainly focused on the chloride type brine systems − or the mixed electrolyte systems, , and rarely dealt with the sulfate system. To effectively utilize the brine resource, the phase diagram of sulfate systems containing rubidium or cesium should be investigated to obtain more information about the crystallographic forms and phase behavior.…”