四元体系LiCl-LiBO2-Li2SO4-H2O在298.15K时的相平衡  

Phase equilibria of quaternary system LiCl-LiBO_2-Li_2SO_4-H_2O at 298.15 K

作　　者：曹丽娜[1] 李珑[1] 张楠[1] 郭亚飞[1] 邓天龙[1] 

机构地区：[1]天津科技大学化工与材料学院,天津市海洋资源与化学重点实验室,天津300457

出　　处：《化工学报》2016年第4期1117-1122,共6页CIESC Journal

基　　金：国家自然科学基金项目(21276194,41306136,U14076113)~~

摘　　要：采用等温溶解平衡法开展了四元体系Li Cl-Li BO_2-Li2SO_4-H_2O在298.15 K时相平衡实验研究,测定体系溶解度和平衡溶液的折光率、密度、p H和电导率。根据实验数据,分别绘制该四元体系的干基图、水图以及相对应的物化性质–组成图。研究结果表明:在该四元体系298.15 K相图中,有2个无变度共饱点分别为相称共饱点(Li2SO_4·H_2O+Li Cl·H_2O+Li BO_2·2H_2O)和不相称共饱点(Li2SO_4·H_2O+Li BO_2·2H_2O+Li BO_2·8H_2O)、5条溶解度曲线和4个单盐结晶相区(Li2SO_4·H_2O、Li Cl·H_2O、Li BO_2·8H_2O和Li BO_2·2H_2O),无复盐和固溶体产生,属于简单四元体系水合物Ⅱ型相图。实验研究中,发现2种偏硼酸锂水合矿物存在(Li BO_2·8H_2O和Li BO_2·2H_2O),Li Cl对Li2SO_4的盐析效应显著;四元体系平衡溶液物化性质随着溶液中氯化锂浓度的变化呈现规律性的变化。The phase equilibria and phase diagram of the quaternary system（Li Cl-Li BO2-Li2SO4-H2O） at 298.15 K, which was not reported in the literature, were studied with the isothermal dissolution equilibrium method. Solubilities and physicochemical properties including refractive index（nD）, density（ρ）, p H and conductivity（κ） in the quaternary system were determined experimentally. According to the experimental data, the dry-salt diagram, water-phase diagram and the diagram of physicochemical properties versus lithium chloride concentration in the quaternary system were plotted, respectively. The experimental results showed that there were two invariant points named as invariant co-saturated point（Li2SO4·H2O ＋ Li Cl·H2O ＋ Li BO2·2H2O） and incommensurate co-saturated point（Li2SO4·H2O ＋ Li BO2·2H2O ＋ Li BO2·8H2O）, five univariant curves and four crystalline regions corresponding to Li2SO4·H2O, Li Cl·H2O, Li BO2·8H2O and Li BO2·2H2O in the quaternary system at 298.15 K. Neither double salt nor solid solution was formed, and the phase diagram of this system at 298.15 K belonged to hydrate-type Ⅱ. The two kinds of hydrate lithium-containing minerals（Li BO2·2H2O and Li BO2·8H2O） were found for the first time. The salting-out effect of Li Cl in the solution was obvious for the composition of Li2SO4. The diagram of physicochemical properties including nD, ρ, p H and κ versus composition shows that the physicochemical properties were changed regularly with increasing lithium chloride concentration in the solution and the singular values were achieved at the invariant points of the quaternary system at 298.15 K.

关 键 词：水盐体系 相平衡 水溶液 化学分析 硼酸盐 硫酸锂 等温溶解平衡法 

分 类 号：O642.4[理学—物理化学]