Determination of the Solubility of Rhabdophanes LnPO4·0.667H2O (Ln = La to Dy). Issue 28 (29th August 2016)

• Record Type: Journal Article
• Authors: Gausse, Clémence; Szenknect, Stéphanie; Qin, Dan Wen; Mesbah, Adel; Clavier, Nicolas; Neumeier, Stefan; Bosbach, Dirk; Dacheux, Nicolas
• Is Part Of: European journal of inorganic chemistry. Issue 28(2016)
• Page Start: 4615
• Page End: 4630
• Publication Date: 2016-08-29
• Subjects: Rhabdophanes -- Phosphates -- Lanthanides -- Thermodynamics -- Solubility -- Hydrates; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201600517
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : A systematic study of the solubility of the rhabdophanes LnPO4 · 0.667H2 O (Ln = La–Dy) was performed through oversaturation and undersaturation experiments at different temperatures (298–363 K) to demonstrate the reversibility of the equilibria. The structure of the neoformed phase was controlled carefully over the entire temperature range to enable the unambiguous attribution of the solubility products and the derived thermodynamic data to the rhabdophane phases. The log K °s, 0 (298 K) values for LnPO4 · 0.667H2 O ranged from –25.6 ± 0.8 (Pr) to –24.9 ± 1.7 (Eu), and the minimum values were for Pr to Sm, whereas the Δf G ° values at 298 K varied between (–1984 ± 2) and (–2004 ± 2) kJ mol –1 whatever the lanthanide element considered, except for Eu‐rhabdophane, which presented the highest Gibbs energy of formation [(–1896 ± 2) kJ mol –1 ]. From the solubility data obtained at various temperatures, the enthalpies of formation of the rhabdophanes Δf H ° were found to be (–2151 ± 13) to (–2130 ± 12) kJ mol –1, excepted for that of Eu, which reached (–2057 ± 9) kJ mol –1 . Abstract : Solubility experiments are used to determine the thermodynamic properties of the LnPO4 · 0.667H2 O (Ln = La–Dy) rhabdophanes and demonstrate the reversibility of the equilibrium. The variation of the solubility with the ionic radius of the lanthanide is determined. The stability domain of rhabdophanes is more constrained than that of monazites.