四元体系Rb^+,Cs^+,Mg^2+//SO4^2--H2O 298.2 K相平衡研究  

Phase equilibria for quaternary system Rb,Cs,Mg//SO-HO at 298.2 K

作　　者：曾英[1,2] 陈佩君 于旭东 ZENG Ying;CHEN Peijun;YU Xudong(College of Materials and Chemistry&Chemical Engineering,Chengdu University of Technology,Chengdu 610059,Sichuan,China;Center of Panxi Strategic Mineral Resources Multi-Purpose Utilization,Chengdu 610059,Sichuan,China;Meishan Pharmaceutical College,Meishan 620200,Sichuan,China)

机构地区：[1]成都理工大学材料与化学化工学院,四川成都610059 [2]四川省攀西战略矿产资源综合利用协同创新中心,四川成都610059 [3]眉山药科职业学院,四川眉山620200

出　　处：《化工学报》2020年第8期3460-3468,共9页CIESC Journal

基　　金：国家自然科学基金项目(U1607121);四川省科技创新人才项目(2019JDRC0016)。

摘　　要：采用等温溶解平衡法研究了298.2 K下四元体系Rb^+,Cs^+,Mg^2+//SO4^2--H2O的相平衡关系,测定了该体系的溶解度、密度以及折射率,并绘制了相应的稳定相图、水图、密度-组成图和折射率-组成图。研究表明:298.2 K下,该四元体系为复杂四元体系,有复盐Cs2SO4·MgSO4·6H2O和Rb2SO4·MgSO4·6H2O以及固溶体[(Rb,Cs)2SO4]生成。其稳定相图由4个四元共饱点、9条单变量曲线以及6个结晶区组成。四元共饱点中E1、E2、E3为相称共饱点,E4为不相称共饱点。6个结晶相区分别对应3种单盐Rb2SO4、MgSO4·7H2O、Cs2SO4,2种复盐Cs2SO4·MgSO4·6H2O、Rb2SO4·MgSO4·6H2O和1种固溶体[(Rb,Cs)2SO4]。其中,复盐Rb2SO4·MgSO4·6H2O结晶区最大,表明其在该体系中最易结晶析出;Cs2SO4结晶区最小。平衡液相的密度和折射率随着溶液中Cs2SO4含量变化呈规律性变化。该体系稳定相图将为硫酸镁亚型盐湖卤水中的铷、铯等资源开发利用提供理论依据。Phase equilibria for the quaternary system Rb^+,Cs^+,Mg^2+//SO4^2-H2O at 298.2 K was studied by an isothermal dissolution equilibrium method.The solubilities,densities,and refractive indices of the system at equilibrium were also determined experimentally.Based on the measured data,the stable phase diagram,and diagrams of density vs composition,refractive index vs composition were plotted.The results show that the quaternary system belongs to a complex type at 298.2 K with the double salts Cs2SO4·MgSO4·6H2O,Rb2SO4·MgSO4·6H2O,and solid solution[(Rb,Cs)2SO4]formed.The phase diagram consists of 4 invariant points,9 uni variant curves,and 6 crystallization zones.Invariant points E1,E2,and E3 belong to commensurate type,while invariant point E4 belongs to incommensurate type.The crystallization zones corrsepond to 3 single salts Rb2SO4,MgSO4·7H2O,Cs2SO4,2 double salts Cs2SO4·MgSO4·6H2O and Rb2SO4·MgSO4·6H2O,1 solid solution[(Rb,Cs)2SO4].The crystallization zone of double salt Rb2SO4·MgSO4·6H2O is the largest,while the crystallization zone of single salt Cs2SO4 is the smallest,which indicating that Rb2SO4·MgSO4·6H2O is most easily crystallized.The densities and refractive indices change regularly with the changing of Cs2SO4 content of the solution.The stable phase diagram of the system will provide a theoretical basis for the development and utilization of resources such as rubidium and cesium in the magnesium sulfate subtype salt lake brine.

关 键 词：相平衡 等温溶解平衡法 复盐 固溶体 溶解度 

分 类 号：O642[理学—物理化学]