NaOH-NaAl(OH)_4-H_2O溶液体系渗透系数的测定及离子作用模型

Determination of Osmotic Coefficients and Representation with Ion-interaction Model for NaOH-NaAl(OH)_4-H_2O System at 303.15 K

用等压法测定了在303.15 K时总碱质量摩尔浓度mNaOH(T)[mNaOH+mNaAl(OH)4]从0.61 mol/kg到5.72mol/kg,苛性比αK[mNaOH(T)/mNaAl(OH)4]从1.98到7.04的NaOH-NaAl(OH)4-H2O溶液体系的等压平衡浓度和渗透系数,并得到该溶液体系的水活度.用Pitzer模型对实验结果进行了参数化研究,拟合求得了离子相互作用参数.用Pitzer模型计算的渗透系数值与实验结果一致.用获得的参数计算了NaOH和NaAl(OH)4在NaOH-NaAl(OH)4-H2O溶液体系中的活度系数,其值随总碱质量摩尔浓度的增加呈增加的趋势.

The isopiestic equilibrium molalities and the osmotic coefficients for the NaOH-NaAl（OH）4-H2O system were measured using isopiestic method.At 303.15 K with the total alkli molality[mNaOH（T）=mNaOH＋mNaAl（OH）4] from 0.61 mol/kg to 5.72 mol/kg and molar ratio of Na2O to Al2O3（αK）[mNaOH（T）/mNaAl（OH）4] from 1.98 to 7.04.The experimental data were represented by the Pitzer model.The Pitzer ion interaction parameters were evaluated from experimental data using multiple regression.The measured data of osmotic coefficients are in reasonable agreements with those calculated by the model.The activity coefficients of NaOH and NaAl（OH）4 in the system were calculated from the ion interaction model parameterized,and the values increased with the total alkli molality increasing.These studies are useful to improve the thermodynamic model for sodium aluminate solutions systems and sodium aluminosilicate solutions systems.