Phase Equilibria for the Aqueous Reciprocal Quaternary System K+, Mg2+//Cl–, Borate–H2O at 298 K

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• 作者：Shanshan Guo ; Xudong Yu ; Ying Zeng
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2016
• 出版时间：April 14, 2016
• 年：2016
• 卷：61
• 期：4
• 页码：1566-1572
• 全文大小：393K
• 年卷期：0
• ISSN：1520-5134

文摘

The phase equilibria of the quaternary system K⁺, Mg²⁺//Cl^–, borate–H₂O were studied at T = 298 K using an isothermal dissolution method. On the basis of the experimental data, the stable equilibrium phase diagram and the diagrams of the density versus composition and refractive indices versus composition of this quaternary system at 298 K were constructed. This phase diagram consists of three invariant points, seven univariant curves, and five crystallization fields corresponding to the single salt MgB₄O₇·9H₂O, KCl, MgCl₂·6H₂O, K₂B₄O₇·4H₂O, and the double salt KCl·MgCl₂·6H₂O. The largest crystallization field is MgB₄O₇·9H₂O; the smallest crystallization field is MgCl₂·6H₂O. By comparison with the stable phase diagram of system K⁺, Mg²⁺//Cl^–, borate–H₂O at 288, 298, and 323 K, the crystalline forms of salts are not changed, and the crystalline form of borate are B₄O₅(OH)₄^2–. The crystallization field of MgB₄O₇·9H₂O decrease obviously at 323 K. The crystallization region of KCl and K₂B₄O₇·4H₂O increases evidently, and the crystallization region of MgCl₂·6H₂O and KCl·MgCl₂·6H₂O changes slightly, meaning temperature has little impact on the solubility of KCl·MgCl₂·6H₂O and MgCl₂·6H₂O.