Stable Phase Equilibrium in the Aqueous Quaternary System RV, Mg2+//Cl-, borate-H2O at 323 K
Stable Phase Equilibrium in the Aqueous Quaternary System RV, Mg2+//Cl-, borate-H2O at 323 K
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DOI：
10.1021/acs.jced.6b00024
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发表时间：
2016-07-01
期刊：
影响因子：
--
通讯作者：
Yu, Xudong
中科院分区：
文献类型：
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作者：
Zeng, Ying;Xie, Gang;Yu, Xudong
季系水盐体系RV、Mg2+// Cl-、硼酸盐- h2o是四川平落地下卤水组成的重要子系统。采用等温溶解平衡法研究了体系的相平衡，测定了体系平衡溶液的溶解度、密度和折射率。根据溶解度数据，得到了等温溶解相图、水图、密度组成图和折射率组成图。结果表明，该四元体系是一个复杂的互易体系，形成双盐RbCl中心点MgCl2中心点6H(2)O。三个不变点和七条不变曲线将相图划分为五个结晶区。这5个结晶区分别对应4种单盐：氯化铷（RbCl）、白方石(MgCl（2)6H(2)O）、五硼酸铷四水合物(RbB5O6(OH)（4)中心点2H(2)O）、黄辉石(MgB4O5(OH)（4)中心点7H(2)O）和一种双盐铷光卤石（RbCl- mgcl2中心点6H(2)O）。RbB5O6(OH)(4)中心点2H(2)O的结晶场最大，MgCl2中心点6H(2)O的结晶场最小。对比323 K和348 K时的稳定相图，盐的结晶形式没有变化，但随着温度的升高，盐的结晶场RbB5O6(OH)(4)中心点2H(2)O明显变大；温度的升高有利于RbB5O6(OH)(4)中心点2H(2)O从溶液中分离。
The quaternary water-salt system RV, Mg2+// Cl-, borate -H2O is an important subsystem of the composition of Pingluo underground brine, Sichuan province. An isothermal dissolution equilibrium method was used to study the phase equilibrium of the system, and the solubilities, densities, and refractive indices of the equilibrated solution of the system were determined. On the basis of the solubility data, the isothermal dissolution phase diagram, the water figure, the diagrams for the density-composition and refractive index -composition were obtained. Results suggest that the quaternary system is of a complex reciprocal system with the formation of double salt RbCl center dot MgCl2 center dot 6H(2)O. Three invariant points and seven univariant curves divide the phase diagram into five crystalline zones. The five crystalline regions correspond to four single salts, rubidium chloride (RbCl), bischofite (MgCl(2)6H(2)O), rubidium pentaborate tetrahydrate (RbB5O6(OH)(4)center dot 2H(2)O), and hungchaoite (MgB4O5(OH)(4)center dot 7H(2)O), and one double salt rubidium-carnallite (RbCl-MgCl2 center dot 6H(2)O). The size of the RbB5O6(OH)(4)center dot 2H(2)O crystallization field is the largest, whereas that of MgCl2 center dot 6H(2)O is the smallest. Comparisons between the stable phase diagrams at 323 K and 348 K show that there is no change with the crystallization forms of the salts, while the crystallization field of salt RbB5O6(OH)(4)center dot 2H(2)O becomes obviously larger with the increase of temperature; a rise in temperature is beneficial to separate RbB5O6(OH)(4)center dot 2H(2)O from the solution.