NaOH-Na_2H_2SiO_4-H_2O体系渗透系数的等压法测定及离子作用模型  

Isopiestic Determination of Osmotic Coefficients and Representation with Ion-interaction Model for NaOH-Na_2H_2SiO_4-H_2O System

作　　者：肖刘萍[1] 刘士军[1] 宋婷[1] 陈启元[1] 

机构地区：[1]中南大学化学化工学院,长沙410083

出　　处：《化学学报》2011年第22期2653-2657,共5页Acta Chimica Sinica

基　　金：国家自然科学基金(No.20873182)资助项目

摘　　要：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.The isopiestic molalities have been measured for the system NaOH-Na2H2SiO4-H20 by isopi- estic method in the ionic strength ranges from 0.5695 to 6.4775 mol·kg-1 and modulus （mole ratio of SiO2 to Na20） 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 system＇s thermody- namic properties well. The mean activity coefficients of NaOH and Na2H2SiO4 were also calculated for the NaOH-NaEH2SiO4-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- NaEH2SiO4-H2O system.

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 

分 类 号：O642[理学—物理化学]