三元体系Li_2B_4O_7-K_2B_4O_7-H_2O 273 K稳定相平衡研究  

Phase equilibrium in Li_2B_4O_7-K_2B_4O_7-H_2O aqueous ternary system at 273 K

作　　者：张婷婷[1] 桑世华[1,2] 傅超[1] 王伟[1] ZHANG Ting-ting SANG Shi-hua FU Chao WANG Wei(College of Materials and Chemistry ＆ Chemical Engineering, Chengdu University of Technology, Chengdu 610059, Sichuan Province, China Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, Chengdu 610059, Sichuan Province, 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]矿产资源化学四川省高校重点实验室,四川成都610059

出　　处：《化学工程》2017年第3期37-41,共5页Chemical Engineering(China)

基　　金：国家自然科学基金委员会-青海省人民政府柴达木盐湖化工科学研究基金(U1407108);四川省教育厅高校科研创新团队(15TD0009)联合资助项目

摘　　要：应用等温溶解平衡法研究了三元体系Li_2B_4O_7-K_2B_4O_7-H_2O 273 K时的稳定相平衡,测定了该体系饱和溶液的溶解度和密度。通过实验数据和固相组成分别绘制了三元体系Li_2B_4O_7-K_2B_4O_7-H_2O 273 K时的相图以及相应的密度-组成图。该体系的稳定相图包含一个共饱点,对应的平衡固相为Li_2B_4O_7·3H_2O和K_2B_4O_7·4H_2O,共饱点液相组成(质量分数)为Li_2B_4O_72.27%,K_2B_4O_79.80%,两条单变量曲线,两个固相结晶区,分别对应Li_2B_4O_7·3H_2O和K_2B_4O_7·4H_2O。实验结果表明:体系属于简单共饱型,没有形成复盐和固溶体;Li_2B_4O_7·3H_2O和K_2B_4O_7·4H_2O之间存在相互盐溶作用;在共饱点处,饱和溶液的密度达到最大。同时,对该三元体系在273,288,298,348 K不同温度时的稳定相图作了对比分析和讨论,发现该体系两种盐在不同温度下有相同的结晶形式。The stable phase equilibrium in Li2B4O7-K2B4O7-H2O ternary system at 273 K was studied using isothermal solubility equilibrium method, and the solubilities of salts and densities of the saturated solution were determined. According to the experimental data and the composition of solid phase, the phase diagram of the Li2BnOT-K2BnO7-H2O ternary system at 273 K and the corresponding density- composition diagram were plotted, respectively. The stable phase diagram included by an invariant point, corresponding to Li2B4O7·3H2O and K2B4O7·4H2O, the compositions （mass fraction） of liquid phase were 2.27% for Li2B4O7and 9.80% for K2B4O7 in the invariant point, two univariant solubility curves, two solid phase crystalline regions, corresponding to Li2B4O7 · 3H2O and K2B4O7·4H2O, respectively. The results show that the ternary system belongs to simple eosaturated type and there are neither double salts nor solid solutions, there are salt-dissolution effect in Li2B4O7 · 3H2O and K2B4O7·4H2O. In addition, the density of saturated solution reaches maximized in the invariant point. At the same time, a comparative analysis and discussion were made for the stable phase diagrams of the system at 273, 288, 298, 348 K. It was found that the two salts had the same crystal forms at different temperatures in the system.

关 键 词：相平衡 溶解度 四硼酸锂 四硼酸钾 

分 类 号：O642.42[理学—物理化学]