Kangrui Sun,Ziwei Bi,Yanqin Meng,Yafei Guo,Lingzong Meng,Tianlong Deng
The salt-water interactions on single salt aqueous solutions of cesium sulfate and cesium chloride, as well as their mixing solutions, have been investigated by a combination of density measurements by an Anton Paar Digital vibrating-tube densimeter and the correction of the Pitzer model of electrolyte. The volumetric properties including apparent molar volume ( V ϕ ) and the coefficient of thermal expansion of the solution ( α ) of the binary systems (CsCl + H 2 O), (Cs 2 SO 4 + H 2 O) and the ternary system (CsCl + Cs 2 SO 4 + H 2 O) from 283.15 to 363.15 K at 5 K intervals and atmospheric pressure were derived. Variation trends of these volumetric properties against temperature and molality were revealed minutely. The Pitzer single salt parameters ( β MX 0 v , β MX 1 v and C MX v , MX = CsCl and Cs 2 SO 4 ), mixing ion-interaction parameters ( θ Cl , S O 4 v and ψ Cs , Cl , S O 4 v ) as well as the correlation coefficient a i in the temperature-dependence equation ( F ( i, p, j ) = a 1 + a 2 ln( T /298.15) + a 3 ( T -298.15) + a 4 /(620- T ) + a 5 /( T -227)) have been obtained according to Pitzer ion-interaction model of electrolytes. These results are helpful to understanding the ion-interaction of aqueous solutions.
Lu Jia,Li Shu’ni,Zhai Quanguo,Jiang Yucheng,Hu Mancheng
The mean activity coefficients for CsCl in N -methylformamide or urea ( w ) + H 2 O (1 − w ) systems were determined in this work by potentiometry, using ion-selective electrodes at 298.15 K. The value of mass fraction w was varied between 0.00 and 0.40 in five unit-steps and the molality of CsCl was between 0.0020 and 1.4009 mol·kg −1 . The experimental data have been correlated with the Pitzer, modified Pitzer and the extended Debye–Hückel equations. The resulting values of the mean activity coefficients, the osmotic coefficients and the standard Gibbs energy of transfer, together with the Pitzer ion-interaction parameters ( β
(0) , β
(1) and C
φ ), extended Debye–Hückel parameters ( a , c and d ), and modified Pitzer parameters ( b , B
MX , C
MX ) are reported for the investigated systems.
Ran Maobiao,Gou Xiaoliang,Wang Pingping,Chen Shunzhang,Shu Xiaoyan,Liu Yi,Zhang Shengdong,Lu Xirui
In this study, the pollucite solidified form was hydrothermally synthesized by metakaolin, non-radioactive CsCl, and NaOH to immobilize CsCl in the radioactive molten salt waste. At 200 °C, the immobilization ratio of Cs increased with the enhancement of reaction system alkalinity by NaOH, but it was also accompanied by the formation of sodalite. Excessive Si was adverse to the crystallization of the solidified form. In addition, the proportion of Cs in the solidified form was constrained by the substitution competition between Cs + and Na + , which was affected by reaction time. The nucleation and growth of pollucite mainly occurs from 2 to 4 h, and the CsCl immobilization ratio could reach 36.27 wt .% at 6 h. The thermal weight loss rate of the solidified form within 1000 °C was less than 4 wt .%, and the normalized leaching rate of Cs was 5.05 × 10 –5 g m −2 d −1 for 14 d, showing reliable thermal stability and chemical durability. Graphical abstract
The equilibrium potentials of Me(III)/Me (Me = Dy, U) couples and the double Me–Ga, Me–Cd alloys vs. Cl − /Cl 2 reference electrode were measured at the temperature range 673–973 K in molten LiCl–KCl–CsCl eutectic by open-circuit potentiometry. The apparent standard potential and the base thermodynamic properties of alloys were determined. Separation factor for Dy/U couple was calculated on gallium and cadmium electrodes. In addition, it was found that the application of gallium electrodes has a significant advantage over cadmium electrodes in the process of electrochemical separation of uranium and dysprosium.
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