盐湖卤水体系中含有重要的铯资源,开展含铯体系的热力学性质研究可以为盐湖卤水综合开发利用打下基础.文章采用铯离子选择性电极(Cs-ISE)和溴离子选择性电极(Br-ISE),组成电池Cs-ISE|CsBr(m),1,3-丁二醇(1,3-BD)(w),H2O(1-w)|Br-ISE,测量了 298.2 K 时 CsBr 在(1,3-BD+H2O)混合溶剂中的电动势,其中,1,3-BD 在(1,3-BD+H2O)混合溶剂中的质量分数w％=0,0.10,0.20,0.30.通过Nernst方程分别与Debye-Hückel模型和Pitzer模型相关联,得到了(CsBr+1,3-BD+H2O)体系的热力学性质,包括平均离子活度系数(γ±)、过量吉布斯自由能(GE)和标准迁移吉布斯自由能(ΔGt(Θ)).结果表明,Debye-Hückel模型和Pitzer模型均能准确描述该体系.CsBr的活度系数γ±随混合体系中CsBr含量的增加而减小,当CsBr含量一定时,γ±随混合溶剂中1,3-BD含量的增加而减小.实验测得该体系的ΔG(Θ)＞0,说明CsBr从水中迁移到(1,3-BD+H2O)混合溶剂的过程是非自发行为.
Thermodynamic Properties of the(CsBr+1,3-Butanediol+H2O)System at 298.2 K
Salt lake brine system contains important cesium resources,and the study on the thermodynamic properties of the cesium system can provide basis for the comprehensive development of salt lake brine.Ce-sium ion selective electrode(Cs-ISE)and bromine ion selective electrode(Br-ISE)were used to compose the cell Cs-ISE|CsBr(m),1,3-butanediol(1,3-BD)(w),H2O(1-w)|Br-ISE,the electric potential of CsBr in(1,3-BD+H2O)mixed solvent at 298.2 K was measured,where the mass fraction of 1,3-BD in the(1,3-BD+H2O)solvent mixture w％=0,0.10,0.20,0.30.By associating Nernst equation with Debye-Hückel model and Pitzer model respectively,the thermodynamic properties of(CsBr+1,3-BD+H2O)sys-tem are obtained,activity coefficients(γ±),excess Gibbs energy(GE)and standard Gibbs energies of trans-ference(ΔGt(Θ)).The comparison results show that both the extended Debye-Hückel and Pitzer models can accurately describe the system.The activity coefficient y±decreases with the increase of CsBr content in the mixed system.When the CsBr content is constant,y±decreases with the increase of 1,3-BD content in the mixed solvent.The experimental results show that the system ΔG(Θ)＞0,indicates that the transference of CsBr from water to the(1,3-BD+water)solvent mixture is not spontaneous.
Potentiometric methodCsBrActivity coefficientDebye-Hückel modelPitzer model
万方数据
维普
