2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 9: Molten Salts and Ionic Liquids, Energy Production

Editors:	Kongoli F, Gaune-Escard M, Turna T, Mauntz M, Dodds H.L.
Publisher:	Flogen Star OUTREACH
Publication Year:	2016
Pages:	390 pages
ISBN:	978-1-987820-24-9
ISSN:	2291-1227 (Metals and Materials Processing in a Clean Environment Series)

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Mixing Enthalpy of LnX3-MX Lanthanide(III)–Alkali Metal Halide Systems

Leszek Rycerz¹; Ida Chojnacka¹; Slobodan Gadzuric²; Marcelle Gaune-Escard³;
¹WROCLAW UNIVERSITY OF SCIENCE AND TECHNOLOGY, Wroclaw, Poland; ²FACULTY OF SCIENCES, UNIVERSITY OF NOVI SAD, Novi Sad, Serbia and Montenegro (formerly Yugoslavia); ³AIX-MARSEILLE UNIVERSITé/POLYTECH, CNRS/IUSTI UMR7343, Marseille, France;
Type of Paper: Regular
Id Paper: 428
Topic: 13

Abstract:

All LnX3-MX binary systems (M = Li, Na, K, Rb, Cs; Ln = lanthanide; X = halide) are characterized by negative enthalpies of mixing. The molar mixing enthalpy exhibits a minimum shifted towards the alkali halide-rich composition and located in the vicinity of x(LnX3) ≈ 0.3-0.4. The alkali metal ionic radius influences both the mixing enthalpy magnitude as well as its minimum location. The smaller the alkali metal ionic radius, the smaller the mixing enthalpy absolute value and the minimum more shifted towards the alkali bromide-rich composition. The comparison of different LnX3-MX binary systems (Ln = lanthanide, X = Cl, Br, I) showed that mixing enthalpy also depends on lanthanide and halide ionic radii. Its absolute value increases reversely with lanthanide and halide ionic radii. In all the LnX3-MX binary systems, a negative value of interaction parameter λ is observed, λ representing the energetic asymmetry of the melts under investigation. Its absolute value increases significantly with the ionic radius of alkali metal cation. All systems exhibit more negative values of the interaction parameter in the alkali halide-rich compositions. The nature of the relationship between the interaction parameter and composition depends on the alkali metal cation. In the systems containing lithium and sodium halides, this dependence is practically linear. Starting from potassium halide, a broad minimum occurs at a lanthanide halide molar fraction x(LnX3) of about 0.2-0.3. This minimum can be undoubtedly ascribed to the formation of LnX63- octahedral complexes in the related systems.

Keywords:

Mixing Enthalpy;molten salt; Lanthanide; alkali Metal; Halides; Interaction Parameter


Cite this article as:

Rycerz L, Chojnacka I, Gadzuric S, Gaune-Escard M. Mixing Enthalpy of LnX3-MX Lanthanide(III)–Alkali Metal Halide Systems. In: Kongoli F, Gaune-Escard M, Turna T, Mauntz M, Dodds H.L., editors. Sustainable Industrial Processing Summit SIPS 2016 Volume 9: Molten Salts and Ionic Liquids, Energy Production. Volume 9. Montreal(Canada): FLOGEN Star Outreach. 2016. p. 113-114.