Determination of Solubility Products of Rare Earth Fluorides by Fluoride Ion-selective Electrode

Abstract

Solubility product values of the rare earth fluorides were determined potentiometrically by using fluoride ion-selective electrodes at 25.0 °C. The pKsp values of the lanthanoid fluorides decreased gradually from 20.0 to 16.9, while the value for yttrium fluoride was locate in between those of terbium and dysprosium fluorides. The value for scandium fluoride was appreciably smaller than any of the lanthanoid fluorides, as expected from the cationic radii. The solubility product value of lanthanum fluoride single crystal could not be determined, since the saturated solution was not obtained through measurements of over three months.

Hydrothermal transport, deposition, and fractionation of the REE: Experimental data and thermodynamic calculations

“…These extrapolations (Fig. 14) yield solubility products at 25°C that are in good agreement with the values determined by Itoh et al (1984) and Frausto da Silva and Queimado (1973) for all REE. As the data reported in the summary of Konings and Kovács (2003) satisfactorily predict the temperature dependence of the solubility products of all REE fluorides, we conclude that the standard entropies and the temperature dependent heat capacity functions for all the REE fluorides reported by them are reliable and that the reason for the disagreement over the solubility products of the LREE fluorides is errors in the calorimetrically determined standard enthalpies of formation of the La, Ce, Pr, and Nd fluorides.…”

“…13). The most consistent datasets are those of Itoh et al (1984) and Frausto da Silva and Queimado (1973). The solubility products calculated using the calorimetric data of Konings and Kovács (2003) compare reasonably well with the experimental values of Itoh et al (1984) and Frausto da Silva and Queimado (1973) for HREE and MREE, but differ considerably from those for LREE.…”

“…The most consistent datasets are those of Itoh et al (1984) and Frausto da Silva and Queimado (1973). The solubility products calculated using the calorimetric data of Konings and Kovács (2003) compare reasonably well with the experimental values of Itoh et al (1984) and Frausto da Silva and Queimado (1973) for HREE and MREE, but differ considerably from those for LREE. Migdisov et al (2009) extrapolated the solubility products determined experimentally for 150, 200, and 250°C down to 25°C using the entropy and heat capacity data reported by Konings and Kovács (2003), and the data listed in Table 2.…”

Multistimuli‐responsive White Luminescent Fluids Using Hybrid Lanthanide Metal–Coordinate Complex Probes

“…These species are fully quenched upon further addition of 1.0 equiv of F − , leading to the generation of blue solution of "free" Tpy ligand ( λ em = 413 nm) with CIE coordinates of (0.15, 0.16) and giving rise to visible precipitates of LnF 3 ( K sp(LaF3) = 3.26 × 10 −21 , K sp(EuF3) = 1.37 × 10 −19 , and K sp(TbF3) = 2.85 × 10 −19 ). [ 24 ] Notably, cyanide, as a strong fi eld ligand and another competing electron donor, can also disengage the Ln(III)-Tpy coordination bonds ( Figure S10a, Supporting Information, inset), while no signifi cant changes in luminescence were observed for anions such as Cl − , Br − , I − , NO 3 − , CO 3 2− , and SO 4 2− , demonstrating the selective chemochromic ability of our simple molecular luminescent platform. This robust selectivity is due to the luminescence switch-off mechanism observed for hybrid material 1 by F − and CN − , in contrast to lanthanide complex anion sensors based on luminescence signal enhancement by replacement of coordinate water molecules.…”

Selective matrix removal and ICP-OES determination of trace uranium, rare earth elements and yttrium in zircon minerals

“…Moreover, the separation is not complete. The solubility product values reported [17] shows that as the atomic number increases REE-fluorides have increased solubility. Hence, a simpler and environmental friendly separation method was standardized as described below.…”