摘要
采用等温溶解平衡法开展了323.2 K四元体系LiCl+MgCl_(2)+CaCl_(2)+H_(2)O的固液相平衡研究,测定了平衡液相组成及密度、折射率,并绘制了相应的相图。研究发现:323.2 K时,该体系有复盐LiCl·MgCl_(2)·7H_(2)O和2MgCl_(2)·CaCl_(2)·12H_(2)O生成,属于复杂四元体系,其相图包含3个共饱点,7条单变量曲线,5个结晶区(MgCl_(2)·6H_(2)O、LiCl·H_(2)O、CaCl_(2)·2H_(2)O、LiCl·MgCl_(2)·7H_(2)O、2MgCl_(2)·CaCl_(2)·12H_(2)O)。对比298.2 K下该四元体系的相图,发现随着温度升高,氯化钙从CaCl_(2)·6H_(2)O、CaCl_(2)·4H_(2)O转化成CaCl_(2)·2H_(2)O,LiCl·MgCl_(2)·7H_(2)O和MgCl_(2)·6H_(2)O结晶区减小,LiCl·H_(2)O和2MgCl_(2)·CaCl_(2)·12H_(2)O结晶区增大,表明温度升高有利于LiCl·H_(2)O和2MgCl_(2)·CaCl_(2)·12H_(2)O析出。采用PSC模型对该四元体系进行了溶解度计算,计算结果与实验结果基本吻合。
The solid-liquid phase equilibria of the quaternary system LiCl+MgCl_(2)+CaCl_(2)+H_(2)O at 323.2 K were studied by the isothermal dissolution method.The density,refractive index and composition of liquid phase were determined experimentally.The phase diagram of the quaternary system at 323.2 K was plotted.The results show that there are two double salts LiCl·MgCl_(2)·7H_(2)O and 2MgCl_(2)·CaCl_(2)·12H_(2)O formed in the quaternary system,belonging to a complex system.The phase diagram of this quaternary system consists of three invariant points,seven univariate curves,five crystallization fields corresponding to MgCl_(2)·6H_(2)O,LiCl·H_(2)O,CaCl_(2)·2H_(2)O,LiCl·MgCl_(2)·7H_(2)O,2MgCl_(2)·CaCl_(2)·12H_(2)O.Comparing the phase diagram of the quaternary system at 323.2 K and 298.2 K,it has found that with the increase of temperature,calcium chloride is converted from CaCl_(2)·6H_(2)O and CaCl_(2)·4H_(2)O to CaCl_(2)·2H_(2)O,the crystallization fields of LiCl·MgCl_(2)·7H_(2)O and MgCl_(2)·6H_(2)O decrease and the crystallization fields of LiCl·H_(2)O and 2MgCl_(2)·CaCl_(2)·12H_(2)O increase,which indicates that increasing temperature is beneficial to the precipitation of LiCl·H_(2)O and 2MgCl_(2)·CaCl_(2)·12H_(2)O.The solubility of the quaternary system was calculated by using the PSC model,and the calculated results were basically consistent with the experimental results.
作者
陈科
杜理
曾英
任思颖
于旭东
CHEN Ke;DU Li;ZENG Ying;REN Siying;YU Xudong(College of Materials and Chemistry&Chemical Engineering,Chengdu University of Technology,Chengdu 610059,Sichuan,China;Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institution,Chengdu 610059,Sichuan,China)
出处
《化工学报》
EI
CSCD
北大核心
2023年第5期1896-1903,共8页
CIESC Journal
基金
国家自然科学基金项目(U21A2017)。
关键词
相平衡
水溶液
溶解性
热力学性质
锂盐
phase equilibria
aqueous solution
solubility
thermodynamic properties
lithium salt
