Na^+,K^+//Cl^-,B4O_7^(2-)-H_2O四元体系273K介稳相平衡  

Metastable Phase Equilibria of the Quaternary System Na^+,K^+//Cl^-,B4O_7^(2-)-H_2O at 273 K

作　　者：曾英[1] 王瑞林[1] 林晓峰[1] 彭芸[1] 

机构地区：[1]成都理工大学材料与化学化工学院,成都610059

出　　处：《物理化学学报》2008年第3期471-474,共4页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(40673050)资助项目

摘　　要：采用等温蒸发法研究了四元体系Na+,K+//Cl-,B4O27--H2O273K时的介稳相平衡与相图.测定了该体系273K平衡液相中各组分的溶解度及平衡液相的密度;绘制了该体系的介稳相图.该四元体系273K相图由5条溶解度单变量线、4个结晶区及2个共饱和点组成.体系无复盐或固溶体形成.四个结晶区分别对应单盐NaCl、KCl、K2B4O7·4H2O和Na2B4O7·10H2O.共饱点E1处KCl、NaCl及Na2B4O7·10H2O三盐共饱和,所对应的平衡液相组成为w(Cl-)=29.15%,w(B4O27-)=0.64%,w(K+)=5.97%,w(Na+)=15.55%;共饱和点E2处盐KCl、Na2B4O7·10H2O和K2B4O7·4H2O的三盐共饱和,所对应的平衡液相组成为w(Cl-)=22.84%,w(B4O27-)=10.98%,w(K+)=28.01%,w(Na+)=1.53%.同体系298K时的稳定相图相比,273K时硼酸钠的结晶区变大,而硼酸钾、氯化钠结晶区变小.The metastable phase equilibria of the quaternary system Na^＋, K^＋//Cl^-, B4O7^2-H2O were studied at 273 K by isothermal evaporation method. Solubilities and densities of the equilibrium solution of this system were determined. According to the experimental data, the metastable equilibrium phase diagram was plotted. The phase diagram of the system consists of five univariant curves, four crystallization fields and two invariant points. No double salt or solid solution was formed. The four crystallization fields were corresponding to single salt NaCl, KCl, K2B4O7· 4H2O and Na2B4O7· 10H2O, respectively. Invariant point E1 was saturated with salt KCl, NaCl and Na2B4O7· 10H2O, the mass fraction composition of the equilibrium solution corresponding to Ex is w（Cl ）=29.15%, w（B4O7^2-）=0.64%, w（K^＋）= 5.97%, w（Na^＋）=15.55%, while that of point E2 was w（Cl^-）=22.84%, w（B4O7^2-）=10.98%, w（K^＋）=28.01%, w（Na^＋）=1.53%. Point E2 is saturated with salt KCl, Na2B4O7· 10H2O and K2B4O7· 4H2O. Compared with the stable phase diagram at 298 K, the crystallization field of Na2B4O7· 10H2O became large at 273 K in this system, whereas the crystallization fields of K2B4O7· 4H2O and NaCl became small.

关 键 词：四元体系 介稳相平衡 硼酸盐 

分 类 号：O642.4[理学—物理化学]