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化学学报
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化学学报 ›› 2011, Vol. 69 ›› Issue (22): 2653-2657. 上一篇    下一篇

研究论文

NaOH-Na2H2SiO4-H2O体系渗透系数的等压法测定及离子作用模型

肖刘萍，刘士军*，宋婷，陈启元   

  1. (中南大学化学化工学院 长沙 410083)
  • 投稿日期:2011-05-15 修回日期:2011-06-23 发布日期:2011-07-14
  • 通讯作者: 刘士军 E-mail:liushijun@hotmail.com
  • 基金资助:

    Na2O-Al2O3-SiO2-H2O复杂溶液体系的热力学研究

Isopiestic Determination of Osmotic Coefficients and Representation with Ion-interaction Model for NaOH-Na2H2SiO4-H2O System

XIAO Liu-Ping, LIU Shi-Jun, SONG Ting, CHEN Qi-Yuan   

  1. (College of Chemistry and Chemical Engineering, Central South University, Changsha 410083)
  • Received:2011-05-15 Revised:2011-06-23 Published:2011-07-14

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采用等压法测定了313.15 K下NaOH-Na2H2SiO4-H2O体系在0.5695～6.4775 mol•kg－1的离子强度范围及0.1461～0.3158的模数(SiO2与Na2O的物质的量比)范围内的等压平衡浓度, 计算了该混合体系的渗透系数和水活度. 用Pitzer离子相互作用模型对实验结果进行了参数化研究, 拟合求取了Pitzer离子相互作用参数. 用Pitzer模型计算的渗透系数值与实验结果一致, 说明该模型能较好的描述NaOH-Na2H2SiO4-H2O体系的热力学性质. 用Pitzer模型计算得到了该体系的各组分平均活度系数随离子强度及模数的变化规律, 并与Mckay-Perring方程计算得到的NaOH的平均活度系数进行了比较, 指出Mckay-Perring方程的适用性.

关键词: NaOH-Na2H2SiO4-H2O体系, 等压法, 渗透系数, Pitzer模型, 平均活度系数, Mckay-Perring方程

The isopiestic molalities have been measured for the system NaOH-Na2H2SiO4-H2O by isopiestic method in the ionic strength ranges from 0.5695 to 6.4775 mol•kg－1 and modulus (mole ratio of SiO2 to Na2O) range from 0.1461 to 0.3158 at 313.15 K, and the osmotic coefficients and water activities have been calculated from the measurements. The experimental data have been represented by the Pitzer model of osmotic coefficient. The Pitzer ion interaction parameters were evaluated from experimental data using multiple regression. The experimental data of osmotic coefficients measured and calculated by using the Pitzer model are in reasonable agreements. It is shown that the Pitzer model can describe the systems thermodynamic properties well. The mean activity coefficients of NaOH and Na2H2SiO4 were also calculated for the NaOH-Na2H2SiO4-H2O system, and these calculations establish their variations with ionic strength and modulus. The mean activity coefficients of NaOH were compared with those calculated from Mckay-Perring equation, and it was pointed out that the application scope of Mckay-Perring equation for NaOH- Na2H2SiO4-H2O system.

Key words: NaOH-Na2H2SiO4-H2O system, isopiestic method, osmotic coefficient, Pitzer model, mean activity coefficient, Mckay-Perring equation

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