Zeng Ying, Ye Guozhen, Wang Ke, Lv Na, Liao Shuang, Luo Jian, Yu Xudong
College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu610059, Sichuan, P. R. China.
Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institution, Chengdu University of Technology, Chengdu610059, Sichuan, P. R. China.
ACS Omega. 2023 Jan 11;8(3):3339-3347. doi: 10.1021/acsomega.2c07041. eCollection 2023 Jan 24.
The phase equilibria for the quaternary system Li, Rb, Mg//SO - HO at 273.2 K were studied by the isothermal dissolution equilibrium method. Based on the measured data, the space diagram, stable phase diagram, water content diagram, and the diagram of density vs composition are plotted. The stable phase diagram in the system consists of four quaternary invariant points, nine univariate curves, and six crystallization zones. For the invariant points, E and E belong to the commensurate type, and E and E belong to the incommensurate type. The order of the crystallization area is RbSO·MgSO·6HO > 3LiSO·RbSO·2HO > LiSO·RbSO > MgSO·7HO > LiSO·HO > RbSO. The density of the equilibrium liquid changed regularly with the content of RbSO in the solution. By comparing the stable phase diagram of the partial ternary subsystems at = 273.2 K and = 298.2 K, it is found that the crystallization regions of RbSO increases with the decrease in temperature, which indicates that cooling is conducive to the crystallization of RbSO. By comparing the stable phase diagram of the system at = 273.2 K and = 308.2 K, it was found that the system was composed of four invariant points, nine univariate curves, and six crystal regions. The double salt 3LiSO·RbSO·2HO is converted to 3LiSO·RbSO. The crystallization region of single salt MgSO·7HO, RbSO and double salt LiSO·RbSO decreased obviously.
采用等温溶解平衡法研究了四元体系Li、Rb、Mg//SO₄-H₂O在273.2 K时的相平衡。根据测量数据绘制了空间图、稳定相图、含水量图以及密度-组成图。该体系的稳定相图由4个四元不变点、9条单变量曲线和6个结晶区域组成。对于不变点，E₁和E₂属于相称型，E₃和E₄属于不相称型。结晶区域顺序为：Rb₂SO₄·MgSO₄·6H₂O＞3Li₂SO₄·Rb₂SO₄·2H₂O＞Li₂SO₄·Rb₂SO₄＞MgSO₄·7H₂O＞Li₂SO₄·H₂O＞Rb₂SO₄。平衡液相的密度随溶液中Rb₂SO₄含量呈规律变化。通过比较273.2 K和298.2 K时部分三元子体系的稳定相图，发现Rb₂SO₄的结晶区域随温度降低而增大，这表明降温有利于Rb₂SO₄的结晶。通过比较273.2 K和308.2 K时该体系的稳定相图，发现该体系由4个不变点、9条单变量曲线和6个结晶区域组成。复盐3Li₂SO₄·Rb₂SO₄·2H₂O转变为3Li₂SO₄·Rb₂SO₄。单盐MgSO₄·7H₂O、Rb₂SO₄和复盐Li₂SO₄·Rb₂SO₄的结晶区域明显减小。
