Formation of W/O Microemulsions in the Extraction of the Lanthanide Series by Purified Cyanex 301

Quantum Chemistry Study on the Extraction of Trivalent Lanthanide Series by Cyanex301: Insights from Formation of Inner- and Outer-Sphere Complexes

“…This is also consistent with our observation in the study of W/O microemulsions phenomena in extraction of Ho(III) by HC301, that is, the sulfur atoms from the C301 anions cannot replace the oxygen atoms from water molecules in the first coordination shell of Ho(III). 17 In short, the relaxed PES scan demonstrates that light lanthanides can form both inner- and outer-sphere complexes, whereas heavy lanthanides can only form outer-sphere complexes with C301 in the presence of water molecules. Therefore, the Gibbs free energies in the extraction of the Ln(III) series by Cyanex301 should adopt different data corresponding to different metal-ion species, as calculated in Schemes 1 and 2.…”

“…W/O microemulsions were also evidenced in the extraction of heavy Ln­(III). The coordination environments of the heavy Ln­(III) are identical along with the increase of neutralization degree . These studies indicate the complexity of the extraction of Ln­(III) by Cyanex301, but to date, there has been no study to explain the different coordination behavior of Cyanex301 with respect to different Ln­(III).…”

“…The coordination environments of the heavy Ln(III) are identical along with the increase of neutralization degree. 17 These studies indicate the complexity of the extraction of Ln(III) by Cyanex301, but to date, there has been no study to explain the different coordination behavior of Cyanex301 with respect to different Ln(III). Such dramatic differences must be related to the intrinsic properties of different lanthanide ions when they interact with C301 anions, which is imperative to be illuminated.…”

“…In 1995, Zhu et al found that purified Cyanex301, i.e., bis­(2,4,4-trimethylpentyl)­dithiophosphinic acid (denoted as HC301, Figure ), which is a S-donor ligand, could selectively extract Am­(III) from Ln­(III) with an extremely high separation factor over 1000 . Since then, a number of experiments have been carried out to investigate the extraction behaviors and, especially, to identify of the extracted complexes of both An­(III) and Ln­(III) in organic phase. − It was demonstrated by Jensen et al that the structure and metal–donor atom bond distances are indistinguishable within experimental error for similarly sized trivalent lanthanide and actinide cations, despite the extraordinary selectivity of HC301 for trivalent actinide cations over trivalent lanthanide cations . In the extraction of the lanthanides series by HC301, however, our group previously observed different extracted complexes for different lanthanides under the same extraction condition .…”

Green Processing of Strategic Elements Based on Magnetic Nanohydrometallurgy

“…Such concentrates are usually processed by rather elaborate solvent extraction methods and ionic exchange. [44][45][46][47][48][49][50] However, it should be mentioned that lanthanide ions separation is far from trivial, since the elements exhibit very similar chemical properties, and the only possibility of success relies on the exploitation of the so called lanthanide contraction accompanying the increase of the atomic number. Such radial contraction determines the relative trends of the stability constants of the complexes, allowing some discrimination between the elements, which can be employed for separation purposes.…”