NaOH-NaAl(OH)4-H2O体系活度系数的计算模型
来源期刊：中南大学学报(自然科学版)2006年第3期
论文作者：李小斌 任万能 刘桂华 彭志宏 周秋生
文章页码：493 - 497
关键词：Debye-Hückel方程;表观介电常数;活度系数;计算模型
Key words：Debye-Hückel equation; apparent dielectric constant; activity coefficient; calculation mode
摘 要：基于三水铝石在不同温度下的平衡溶解度,依据铝酸钠溶液表观介电常数ε′的概念,应用Debye-Hückel理论,拟合回归出ε′与苛性比(αk)、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αk，m和t的函数表达式,最终将活度系数γ与αk, 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0.1~10 mol/kg,αk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)4活度系数γ和ε′均随αk和m的增大而增大;当αk<5.5时,γ和ε′随t的升高而减小,而当αk>5.5时,γ和ε′均随t的升高而增大。
Abstract: Based on the equilibrium solubility data of gibbsite at various temperatures and the conception of the apparent dielectric constantε′of sodium aluminate solution, and according to the Debye-Hückel theory, a regression equation forε′including molar ratio (αk) of Na2O to Al2O3,molality of NaOH (m) and temperature (t) was obtained. And then, aimed at the obvious errors of activity coefficientγresulting from the magnitude ofε′and no results forε′owing toγ>1, the extended-term parameterbrwas introduced and its equation involving αk,mandtwas also deduced. Activity coefficient was successfully related to αk,m and t, and an activity coefficient calculation model for NaAl(OH)4 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,αk 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 γandε′increase with the increase ofαk or m, and decrease when αk<5.5, but increase when αk>5.5 with the increase of temperatures.
基金信息：国家自然科学基金资助项目
