Molten-salt Solutions

Licour, L. Lopes, Contribution to the Knowledge of the Electrochemical Properties of Actinides in Non-Aqueous Media III. The Reduction of Tetravalent Thorium and Tetravalent Neptunium in Various Organic Solvents, Pages 6-12, 1995, with permission from Elsevier). 

The electrodeposition of thorium, typically as hydrous oxide, has been used as an efficient means of preparing samples for alpha spectrometric determination. Talvi-tie described a procedure at a 304 stainless steel cathode using 1 M (NH4)2S04 at pH 2 for 120 min, with a current density of 520 mA cm [25]. Recently, Lee et al. compared Talvitie s method with a modified version employing the following conditions stainless steel cathode, 300 mA cm current density, 2 h electrolysis, pH of 1.8, and an electrolyte solution containing 0.3 M ammonium oxalate, 0.4 M ammonium sulfate, 0.1 M 

---

In the Godrej-Lurgi process, olefins are produced by dehydration of fatty alcohols on alumina in a continuous vapor-phase process. The reaction is carried out in a specially designed isothermal multitube reactor at a temperature of approximately 300°C and a pressure of 5—10 kPa (0.05—0.10 atm). As the reaction is endothermic, temperature is maintained by circulating externally heated molten salt solution around the reactor tubes. The reaction is sensitive to temperature fluctuations and gradients, hence the need to maintain an isothermal reaction regime. 

Chemical Production. Electrolytic production of chemicals is conducted either by solution (water) electrolysis or fused-salt electrolysis. Fluorine, chlorine, chlorate, and manganese dioxide are Hberated from water solutions magnesium and sodium are generated from molten salt solutions. 

I.D. Efros, M.F. Lantratov, About decomposition voltage of potassium fluorotantalate in molten salts solutions, Metallurgiya, Moscow, 1965 p. 284 (in Russian). 

The stability of complex fluorides in molten salt solutions has also been widely investigated. The studies of cryolite and chiolite in NaF/AlF3 melts by cell methods (67) or by mass-spectrographic examination of vapor species (150) are typical. 

Although the molten salt solutions are extremely complex in that they may contain up to nine components, they behave in a straightforward manner almost exactly like the pseudo-ternary Y2O3 - Fe203 - PbO (20). This simplification permits great... 

The majority of literature concerning the electrochemical behavior of plutonium is focused on results obtained in acidic aqueous or molten salts solutions. Several reviews have appeared on the redox properties of plutonium in... 

Metal-ammonia solutions are to be compared with molten salt solutions of the type KI-K, which show a two-phase region (Bredig 1964, Warren 1985), and with caesium vapour. This was emphasized particularly by Krumhansl (1965). 

Solutions containing a high concentration of excess electrons display a transition to the metallic state. Thus, for sodium-ammonia solutions in the concentration region 1-6 M the specific conductance increases by about three orders of magnitude, and the temperature coefficient of the conductance is very small (27). Similar behavior is exhibited by other metal-ammonia solutions (but surprisingly, not by concentrated lithium-methylamine solutions ) (10) and by metal-molten salt solutions (17). 

Causo, M.S., Ciccotti, G., Montemayor, D., Bonella, S., Coker, D.F. An adiabatic linearized path integral approach for quantum time correlation functions electronic transport in metal-molten salt solutions. J. Phys. Chem. B 109 6855... 

Reactions in Molten Salt Solutions. I. Uranate and Neptunate Formation in Molten Lithium Nitrate-Sodium Nitrate, W.T. Camall, S.J. Neufeldt, and A. Walker, Inorg. Chem. 4, 1808-1813 (1965). 

Blander M., Thermodynamic Properties of Molten Salt Solutions mMoltenSalt Chemistry, M. Blander, ed., Interscience, New York, 1964, p. 127. 

No Bi2Xi compound is known, but it has long been known that when metallic bismuth is dissolved in molten BiCl3 a black solid of approximate composition BiCl can be obtained. This solid is Bi24Cl28, and it has an elaborate constitution, consisting of four BiCll", one Bi2Clg, and two Bi + ions, the structures of which are depicted in Fig. 10-5. The electronic structure of the Bi + ion, a metal atom cluster, is best understood in terms of delocalized molecular orbitals. Other low-valent species present in various molten salt solutions are Bi+, Bi3+, Bi +, and Bi +. The last, in Bi8(AlCl4)2, has a square antiprismatic structure. 

In a molten salt solution of CdClj in KCl, radiotracer measurements of the diffusion coefficient of Cd at 470 °C showed the heat of activation to be 23.0 kJ moC. A rough calculation of the entropy of activation showed this to be small, about 41.8 J mol K ... 

Electronic Transport in a Metal-Molten Salt Solution ... 

In this section we present some applications of the LAND-map approach for computing time correlation functions and time dependent quantum expectation values for realistic model condensed phase systems. These representative applications demonstrate how the methodology can be implemented in general and provide challenging tests of the approach. The first test application is the spin-boson model where exact results are known from numerical path integral calculations [59-62]. The second system we study is a fully atomistic model for excess electronic transport in metal - molten salt solutions. Here the potentials are sufficiently reliable that findings from our calculations can be compared with experimental results. 

The behavior of an excess electron in dilute metal-molten salt solutions has been the subject of many experimental and theoretical studies [69-72]. The details of the model we employ are exactly the same as the early calculations of Selloni and coworkers [71,72]. Specifically, our simulations have been performed on a periodically repeated system of 32 K+ cations, 31 CP anions, and 1 electron. The mass density was set to p = 1.52 x 10 kg/m. The temperature we use here is T = 1800 K. 

E. S. Fois, A. Selloni, and M. Parrinello (1989) Approach to metallic behavior in metal-molten-salt solutions. Phys. Rev. 39, p. 4812... 

Blander, M. Thermodynamic Properties of Molten Salt Solutions, Molten Salt Chemistry, Blander, M., Ed., Interscience, N.Y., 1964, pp. 127-237. 

---