NaOH-NaAl(OH)_4-H_2O体系活度系数的计算模型  

Activity coefficient calculation model for NaAl(OH)_4-NaOH-H_2O system

作　　者：李小斌[1] 任万能[1] 刘桂华[1] 彭志宏[1] 周秋生[1] 

机构地区：[1]中南大学冶金科学与工程学院,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2006年第3期493-497,共5页Journal of Central South University:Science and Technology

基　　金：国家重点基础研究发展规划项目(2005CB623702);国家自然科学基金资助项目(50274076)

摘　　要：基于三水铝石在不同温度下的平衡溶解度，依据铝酸钠溶液表现介电常数ε’的概念，应用Debye-Htickel理论，拟合回归出ε’与苛性比（σk）、苛性碱的质量摩尔浓度（m）和温度（t）的函数关系式。同时，为解决当ε’过大时活度系数（γ）误差较大以及由于活度系数大于1而导致ε’无实数解的问题，借助修正项系数br，并导出br与σk，m和t的函数表达式，最终将活度系数γ与σk，m和t相关联，从而建立NaOH-NaAl（OH）4-H2O体系中NaAl（OH）4的活度系数计算模型。研究结果表明：当t为25～100℃，m为0．1～10mol／kg，σk为1．5～10．5时，活度系数模型计算值与文献实验值之间的相对误差小于10％；NaAl（OH）．活度系数γ和ε’均随σk和优的增大而增大；当σk〈5．5时，γ和ε’随t的升高而减小，而当σk〉5．5时，γ和ε’均随t的升高而增大。Based on the equilibrium solubility data of gibbsite at various temperatures and the conception of the apparent dielectric constant ε’ of sodium aluminate solution, and according to the Debye-Hueckel theory, a regression equation for ε’ including molar ratio （σk） of NazO to Al2O3, molality of NaOH （m） and temperature （t） was obtained. And then, aimed at the obvious errors of activity coefficient γ resulting from the magnitude of ε’and no results for ε’ owing to γ〉1, the extended-term parameter br was introduced and its equation involving σk, m and t was also deduced. Activity coefficient was successfully related to σk, m and t, and an activity coefficient calculation model for NaAl（OH）, in NaAl（OH）4-NaOH-H2O system was established. The results show that the model can be applied when t is 25-100℃, m is 0.1 - 10 mol/kg, σk is 1.5 - 10.5, and the relative errors between the results derived from this method and that of the literature are less than 10%. The values of γ and ε＇increase with the increase of σk or m, and decrease when σk〈5.5, but increase when σk〉5.5 with the increase of temperatures.

关 键 词：Debye-Htickel方程 表现介电常数 活度系数 计算模型 

分 类 号：TF801[冶金工程—有色金属冶金]