二价钛离子在NaCl-KCl熔盐中的活度分析

Activity analysis of divalent titanium in NaCl-KCl molten salt

熔盐电化学工艺是提取与提纯金属钛最具前景的方法。钛离子活度的确定对研究钛的熔盐电解机制具有重要意义。因此,为得到熔盐中二价钛离子浓度与其活度的关系,本文采用开路电位法在三电极体系下测定了含定量钛离子及饱和金属钛的Na Cl-KCl共晶盐中的离子平衡电位,并由Nernst方程计算得出二价钛离子的活度,进而获得了对应的活度因子。结果表明:在1023 K下,当熔盐中二价钛离子摩尔分数介于0.296%~2.378%时,其活度值单调地介于0.00205~0.01877,且其活度因子为0.693~0.998。本研究可为精确确定熔盐中钛离子活度及进一步研究钛离子歧化反应的平衡常数提供重要基础。

Molten salt electrochemical process is the most promising method to extract and purify titanium.The determination of titanium ions activities is of great significance to the study of molten salt electrolysis mechanism of titanium.Therefore,in order to obtain the relationship between the concentration of divalent titanium ion and its activity in molten salt,the ions equilibrium potentials of NaCl-KCl eutectic salt system containing quantitative titanium ions and saturated metal titanium were measured by open circuit potential method in three-electrodes system.The activity of divalent titanium ion was calculated by Nernst equation,and the corresponding activity coefficient was obtained.The results show that the activity values of divalent titanium ions are monotonically ranged from 0.205 and 1.877,the activity coefficients range from 0.693 to 0.998,when the molar fraction of titanium ions ranges from 0.296%to 2.378%at 1023 K.This study can provide an important basis for accurately determining the activity of titanium ion in molten salt and further studying the equilibrium constant of titanium disproportionation reaction.