The Enthalpies of Solution of Lanthanide Metals in Hydrochloric Acid at Various Concentrations. Relevance to Nuclear Waste Long Term Storage

Abstract

Lanthanides / Actinides / Chlorides / Ions / Thermochemistry SummaryThe determination by solution calorimetry of thermochemical data associated with the formation of environmentally important compounds such as lanthanide and actinide hydroxides, hydroxycarbonates and carbonates... requires the knowledge of the molar enthalpies of formation of the relevant cations in the medium -often hydrochloric acid solutions -selected for the dissolution of these compounds. Surprisingly enough, for a number of lanthanides, the data in such media are fragmentary and sometimes contradictory. In this paper, are reported new results on the enthalpy of solution of lanthanum, neodymium, gadolinium, erbium and lutetium, in hydrochloric acid solutions at concentrations up to 6 mol · dm \ using ultra high purity metal samples. The evolution of these enthalpies of solution as a function of the HCl concentration is discussed and compared to the corresponding literature data for trivalent actinides (mainly plutonium and americium).From the measurement of the enthalpies of solution of GdCl·, (cr) and LuCl·, (cr) in media ranging from 6.00 mol · dm"' HCl to 10~3 mol · dm -3 HCl, new values are reported for the standard molar enthalpies of formation of these compounds and of the gadolinium and lutetium ions.Based on these and other determinations which appeared recently in the literature, an evaluation of the status of the standard molar enthalpies of formation of several lanthanide trichlorides and ions is made.

Thermodynamic assessment of NdBr3 unary and LiBr–NdBr3 binary system

“…The estimated enthalpy of formation (−873 kJ/mol), standard entropy (194.1 J/mol K), heat capacity (99.2 J/mol K) at 298.15 K were in good agreement with the data recommended by Cordfunke and Konings [8] and Wick and Block [6]. Cordfunke and Konings [8] evaluated the enthalpy of formation of lanthanide compounds LnCl 3 , LnBr 3 and LnI 3 at 298.15 K and reported the value −864 kJ/mol for the NdBr 3 compound on basis of the experimental data available in literatures [9][10][11][12]. The value indicated by Cordfunke and Konings [8] was adopted in the present optimization.…”

“…2 together with the This work a Based on the measurements of Merli et al [10] and Hurtgen et al [11]. b Based on the work of Cordfunke and Konings [9] and Henning and Oppermann [12].…”

Does the 4f Electron Configuration Affect Molecular Geometries? A Joint Computational, Vibrational Spectroscopic, and Electron Diffraction Study of Dysprosium Tribromide

“…There is considerable practical interest in lanthanide trihalide vapors because of their importance in several industrial processes. They are used, among others, in high-temperature extraction and separation processes for lanthanides, in purification processes of nuclear waste, and in high-pressure metal halide discharge lamps . Dysprosium tribromide itself is one of the most important ingredients of metal halide discharge lamps .…”

Preparation and stability of a new compound SrCe0.9Lu0.1O2.95

“…This solvent was also used by Morss and Menz [24] to determine the formation enthalpy of BaCeO 3 , and Goudiakas et al [23] used it for BaCeO 3 and SrCeO 3 . 1 M HCl is the most suitable solvent for solution calorimeters [25][26][27].…”