高等学校化学学报

高等学校化学学报

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273 K下Na2CO3-Na2SO4-Na2B4O7-H2O四元体系介稳相平衡的实验研究

郑志远1, 曾英1, 陈俊2, 林晓锋1   

    1. 成都理工大学材料与化学化工学院,
    2. 能源学院, 成都 610059
  • 收稿日期:2007-09-13 修回日期:1900-01-01 出版日期:2008-02-10 发布日期:2008-02-10
  • 通讯作者: 曾英

Experimental Study on the Metastable Phase Equilibria of the Quaternary System Na2CO3-Na2SO4-Na2B4O7-H2O at 273 K

ZHENG Zhi-Yuan1, ZENG Ying1*, CHEN Jun2, LIN Xiao-Feng1   

    1. College of Materials and Chemistry & Chemical Engineering,
    2. College of Energy Resources, Chengdu University of Technology, Chengdu 610059, China
  • Received:2007-09-13 Revised:1900-01-01 Online:2008-02-10 Published:2008-02-10
  • Contact: ZENG Ying

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摘要： 采用等温蒸发法研究了四元体系Na2CO3-Na2SO4-Na2B4O7-H2O在273 K时的介稳相平衡及平衡液相的密度. 利用溶解度数据绘制了该四元体系273 K下的相图. 研究结果表明, 该四元体系有异成分复盐2Na2SO4·Na2CO3形成. 相图中有2个共饱点、5条单变量曲线和4个结晶相区. 4个结晶相区分别为盐Na2CO3·10H2O, Na2SO4·10H2O, Na2B4O7·10H2O和2Na2SO4·Na2CO3的结晶区. 复盐2Na2SO4·Na2CO3同时存在于包含Na2CO3-Na2SO4-H2O三元体系的其它四元体系或高元体系中. 在273 K介稳平衡相图中, 碳酸钠以Na2CO3·10H2O形式析出; 硫酸钠以Na2SO4·10H2O的形式析出; 硼酸钠的完整分子式为Na2B4O5(OH)4·8H2O. Na2CO3对Na2B4O7有盐析作用.

关键词: 水盐体系, 介稳相平衡, 钠盐

Abstract: The solubilities and densities of equilibrium solutions in the quaternary system Na2CO3-Na2SO4-Na2B4O7-H2O were studied at 273 K by isothermal evaporation method. On the basis of the solubility data, the phase diagram of the system was plotted. The phase diagram consists of two invariant point, five univariant curves and four crystallization fields, which correspond to the salt Na2CO3·10H2O, Na2SO4·10H2O, Na2B4O7·10H2O and 2Na2SO4·Na2CO3. In this system, the double-salt(2Na2SO4·Na2CO3) was formed, and this double-salt also exists in the other quaternary or higher-component systems which contain the Na2CO3-Na2SO4-H2O ternary system. The crystallization forms of sodium carbonate and sodium sulfate are Na2CO3·10H2O and Na2SO4·10H2O, respectively. The inextenso molecular fomula of sodium borate is Na2B4O5·(OH)4·8H2O. Na2CO3 has salt-out effect to Na2B4O7 in the solution.

Key words: Salt-water system, Metastable phase equilibrium, Sodium salt

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