298.2 K四元体系NH_(4)Cl-CaCl_(2)-SrCl_(2)-H_(2)O稳定相平衡实验  

Stable phase equilibria of quaternary system NH_(4)Cl-CaCl_(2)-SrCl_(2)-H_(2)O at 298.2 K

作　　者：冯珊[1] 于旭东[1] 罗军 郑秋风 刘敏 FENG Shan;YU Xu-dong;LUO Jun;ZHENG Qiu-feng;LIU Min(College of Materials and Chemistry&Chemical Engineering,Chengdu University of Technology,Chengdu 610059,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

出　　处：《高校化学工程学报》2023年第2期194-201,共8页Journal of Chemical Engineering of Chinese Universities

基　　金：四川省科技计划(2017JY0191,2022YFQ0075)。

摘　　要：为了获取铵钙锶共存氯化物体系298.2 K下各盐结晶形式,采用等温溶解平衡法开展298.2 K时四元体系NH_(4)Cl-CaCl_(2)-SrCl_(2)-H_(2)O稳定相平衡研究,测定体系的溶解度和平衡固相组成以及平衡溶液的密度、折光率。根据实验数据,分别绘制该四元体系298.2 K时的稳定相图、密度-组成图和折光率-组成图。结果表明:298.2 K时,NH_(4)Cl-CaCl_(2)-SrCl_(2)-H_(2)O体系稳定相图由3个共饱点、7条单变量曲线、5个结晶相区组成,生成固溶体[(Ca,Sr)Cl_(2)]·6H_(2)O和[(Sr,Ca)Cl_(2)]·6H_(2)O,属复杂四元体系。5个结晶区大小顺序为NH_(4)Cl>SrCl_(2)·6H_(2)O>[(Ca,Sr)Cl_(2)]·6H_(2)O>[(Sr,Ca)Cl_(2)]·6H_(2)O>CaCl_(2)·6H_(2)O,SrCl_(2)·6H_(2)O结晶区远大于固溶体结晶区,通过控制蒸发过程可避免进入固溶体结晶区从而制备得到SrCl_(2)·6H_(2)O产品。In order to obtain crystallization forms of salts containing ammonium,calcium,strontium,and chloride at 298.2 K,stable phase equilibria of the quaternary system NH_(4)Cl-CaCl_(2)-SrCl_(2)-H_(2)O at T=298.2 K was studied using an isothermal dissolution equilibrium method.Solubilities,densities,and refractive indices of the system were determined experimentally.Space diagram,stable phase diagram,and diagrams of density vs composition and refractive index vs composition were obtained based on the measured data.The results show that there are three invariant points,seven isothermal dissolutions,and five crystallization regions in the stable phase diagram of the system NH_(4)Cl-CaCl_(2)-SrCl_(2)-H_(2)O.The system forms solid solution[(Ca,Sr)Cl_(2)]·6H_(2)O and[(Sr,Ca)Cl_(2)]·6H_(2)O and is a complex type.The five crystallization region areas were in the order of NH_(4)Cl>SrCl_(2)·6H_(2)O>[(Ca,Sr)Cl_(2)]·6H_(2)O>[(Sr,Ca)Cl_(2)]·6H_(2)O>CaCl_(2)·6H_(2)O,and the crystallization region of SrCl_(2)·6H_(2)O was larger than that of solid solution.Therefore,SrCl_(2)·6H_(2)O can be separated from the mixed solution by avoiding crystallization in the solid solution crystallization regions during evaporation.

关 键 词：相平衡 热力学性质 溶解性 水合物 固溶体 

分 类 号：O642.4[理学—物理化学]