Understanding the Solid Solution–Aqueous Solution Equilibria in the KCl + RbCl + H2O System from Experiments, Atomistic Simulation and Thermodynamic Modeling

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The specific heat capacity of NaBO 2 (aq) solution was determined using a Calvet-type calorimeter at a temperature from 288.15 to 338.15 K and at a concentration from about 0.25 mol•kg −1 H 2 O to near room temperature solubility limit. Combining these specific heat capacity data and thermodynamic and solid−liquid equilibrium data reported in the literature, a temperature-dependent thermodynamic model was developed for the NaBO 2 + H 2 O system based on Pitzer−Simonson−Clegg activity coefficient equations. The model represents all of the properties over a wide temperature and concentration ranges. Combining the binary models of NaCl + H 2 O and Na 2 SO 4 + H 2 O systems published in the previous studies of our group, multitemperature thermodynamic models of the NaBO 2 + NaCl + H 2 O and NaBO 2 + Na 2 SO 4 + H 2 O systems were constructed. These ternary models reproduce the experimental solubility isotherms reported in the literature in general, but some significant inconsistency is still present. More accurate solubility data for these ternary systems at various temperatures are urgent.

Section: Thermodynamic Modelingmentioning

confidence: 99%

Section: Table 4 Standard Gibbs Free Energy Of the Solid And Aqueous ...mentioning

confidence: 99%

Measurement of Specific Heat Capacity of NaBO₂(aq) Solution and Thermodynamic Modeling of NaBO₂ + H₂O, NaBO₂ + NaCl + H₂O, and NaBO₂ + Na₂SO₄ + H₂O Systems

Dong

et al. 2020

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“…As for the quaternary system K + , Rb + // Cl – , and borate–H 2 O, the phase equilibria of its ternary subsystems K + , Rb + // borate–H 2 O at 323.2 K, K + // Cl – , borate–H 2 O at 273.2–373.2 K, − Rb + // Cl – , borate–H 2 O at 323.2 K and K + , Rb + // Cl – –H 2 O at 298.2–323.2 K − were investigated. It can be found that the system K + , Rb + // Cl – –H 2 O belongs to a complex type with solid solution [(K, Rb)Cl] formed, and the other three ternary subsystems all belong to the simple type.…”

Section: Introductionmentioning

confidence: 99%

Phase Equilibria on the Reciprocal Quaternary System K⁺, Rb⁺ // Cl^–, and Borate–H₂O at T = 323.2 K and p = 94.77 kPa

Yu¹,

Chen

Feng

et al. 2021

The isothermal dissolution method was applied for the phase equilibrium experiment of the quaternary system K+, Rb+ // Cl–, and borate–H2O at T = 323.2 K and p = 94.77 kPa. The solubilities and refractive indices (n D) of the system were determined experimentally. The coexisting salts of the quaternary invariant points were identified using the X-ray diffraction (XRD) method. Based on the measured data, the stable phase diagram and the figures of water content and refractive index (n D) vs composition were plotted for this system at 323.2 K. The results show that the system belongs to a complex type with the formation of a solid solution [(K, Rb)Cl]. The stable phase diagram consists of three quaternary invariant points, seven isothermal dissolution curves, and five crystallization regions corresponding to KCl, RbCl, RbB5O6(OH)4·2H2O, K2B4O5(OH)4·2H2O, and [(K, Rb)Cl]. The size of the RbB5O6(OH)4·2H2O crystallization zone is the largest among the coexisting salts in the quaternary system, which means it is the most easily crystallized from the mixed solution containing potassium, rubidium, chloride, and borate.

“…The research results can be used to explore the chemical production process and guide the formulation of the comprehensive utilization process of salt lake brine resources. 13 Up to now, a lot of work have been carried out on phase equilibrium for different types of salt lakes, for example, K + , Rb + // Cl − − H 2 O at 298.15 K; 14 Na + , Mg 2+ , NH 4 + // Cl − − H 2 O at 348.15 K; 15 Na + , Rb + // Cl − − H 2 O at 288.15, 298.2, and 308.15 K; 16 Na + , Rb + , Mg 2+ //Cl − − H 2 O at 298.2 K; 17 Li + , Rb + , Mg 2+ //borate − H 2 O at T = 323 K; 18 Rb + (Mg 2+ )//Cl − , and borate − H 2 O at 323 K; 19 and Li + , K + , Rb + , Mg 2+ // borate − H 2 O, 20 K + , Rb + , Cs + //SO 4 2− − H 2 O at 298.2 K 21 have been used to comprehensively utilize the salt lake. According to the reported sulfate-containing literature, for the quaternary systems Li + , Na + , Cs + //SO 4 2− − H 2 O at 298.2 K; 22 Li + , Na + , Mg 2+ // SO 4 2− − H 2 O at 323 K, 23 and Li + , Cs + , Mg 2+ // SO 4 2− − H 2 O at 298.2 K, 24 it was found that lithium sulfate is difficult to be extracted directly from brine in its single salt form by isothermal crystallization.…”

Section: Introductionmentioning

confidence: 99%

Stable Phase Diagram of the Quaternary Water–Salt System Li⁺, Na⁺, Rb⁺//SO₄^2–·H₂O at 298.2 and 323.2 K (P = 94.5 kPa)

Ying

Zeng

et al. 2021

The stable phase equilibrium of the quaternary system Li+, Na+, Rb+// SO4 2– – H2O at T = 298.2 and 323.2 K (P = 94.5 kPa) was studied by an isothermal dissolution equilibrium method. The solubilities, density, and refractive index of equilibrated solution were determined. It is found that the projected phase diagrams of the quaternary system at 298.2 and 323.2 K (P = 94.5 kPa) both contain four invariant points, nine univariant curves, and six crystallization regions. By comparing the phase diagrams at 298.2 and 323.2 K, it is found that at 298.2 K, the region of single salt Rb2SO4 is the largest one and that of Li2SO4·H2O is the smallest one. At T = 323.2 K, the single salt Na2SO4·10H2O transforms into Na2SO4 and the lithium sodium double salt is transformed from 3Na2SO4·Li2SO4·12H2O to Li2SO4·Na2SO4. Meanwhile, the maximum phase region shifts from Rb2SO4 to Li2SO4·Na2SO4. This indicates that with the rise of temperature, the solubilities of Rb2SO4 and Li2SO4·Na2SO4 changed significantly and the lithium sodium double salt will be crystallized out from the system in the form of Li2SO4·Na2SO4, with a higher lithium sodium ratio. In other words, it is unfavorable to extract rubidium sulfate from sulfate brine, while it has obvious promoting effects on extracting lithium sulfate.