Complexing in molten mixtures of thorium and alkali halides

✍ Scribed by M.V. Smirnov; V.Ya. Kudyakov

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 893 KB
• Volume: 28
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(83)85188-3

✦ Synopsis

Abstract<omplexing is studied by potentiometry in dilute thorium tetra-and dihalide solutions in molten alkali halides and some of their mixtures. The ernfof cells ThlNThX, + (1 --N)MXjMXllC, Xze, and ThlNThX,+(I-N)[N~Y+(l-N~MX)IMXtC,X,~, in which X is Cl, Br or I, Yis F, Cl or Brand M is Li, Na, K, Cs or Na + K is measured as a function of temperature and mole fraction of ThX,(N) and M Y(N,.j. From experimental observations MzThX,+z decomposition potentials and ThX4 and ThCls activity coefficients are calculated in the melts of XThXa + (1 -X)ThX, + MX (X is a share of tetravalent thorium in equilibrium with metallic thorium in molten alkali halides). Expressions are oblained for their temperature dependences M,ThCII+ z and especially M,ThCI,+ z decomposition potentials increase and ThCl, and ThCI, activity coefficients decrease as the ionic potential of cations diminish in the series of alkali chlorides from LiCl to CsCI. Numbers 2 of addends are evaluated. Complexing reactions of addition are shown 10 take place in melts containing thorium and two different kinds of halide anions. Addend numbers Z and conditional stability constants are found for complex compounds M,ThX.Y, formed by tetra (n = 4)and divalent (n = 2) thorium. Equations are derived for their temperature dependence. The addend number reduces as temperature is raised. The complex thorium halide compound stability decrease s as thorium valency, electronic zp olarizability of anions X-and ionic potential of anions Y-drop in the series of ThI,F$-, ThBc,F,-, ThCl,F$-, Thl,Cl$-, ThI,Brs-, ThBr,Cl$-, ThI,Cl$-, ThBr,Cl$-, Thl,Brg-.