Rare earth separations by selective borate crystallization

Abstract

Lanthanides possess similar chemical properties rendering their separation from one another a challenge of fundamental chemical and global importance given their incorporation into many advanced technologies. New separation strategies combining green chemistry with low cost and high efficiency remain highly desirable. We demonstrate that the subtle bonding differences among trivalent lanthanides can be amplified during the crystallization of borates, providing chemical recognition of specific lanthanides that originates from Ln3+ coordination alterations, borate polymerization diversity and soft ligand coordination selectivity. Six distinct phases are obtained under identical reaction conditions across lanthanide series, further leading to an efficient and cost-effective separation strategy via selective crystallization. As proof of concept, Nd/Sm and Nd/Dy are used as binary models to demonstrate solid/aqueous and solid/solid separation processes. Controlling the reaction kinetics gives rise to enhanced separation efficiency of Nd/Sm system and a one-step quantitative separation of Nd/Dy with the aid of selective density-based flotation.

[Ln6O8] Cluster‐Encapsulating Polyplumbites as New Polyoxometalate Members and Record Inorganic Anion‐Exchange Materials for ReO4− Sequestration

“…[9] Hydrothermal reactions between Ln 2 O 3 , PbO, and HClO 4 at 220 °C resulted in the formation of two distinct phases, LnPbOClO 4 -1 and LnPbOClO 4 -2, with the transition point existing between Ho and Er ( Figure 1a). [10] An identical reaction was conducted on the lanthanide analog Y and it adopts the same structural type as that of Ho rather than Er, which is consistent with the periodic trend based on the ionic radius (Y 1.019 Å > Ho 1.015 Å > Er 1.004 Å, C.N. Similar effect has been observed in other systems including lanthanide borate, lanthanide tellurite sulfate, and lanthanide iodate selenate.…”

Synthesis of molybdenum disulfide/reduced graphene oxide composites for effective removal of Pb(II) from aqueous solutions

“…As shown in Fig. 6f, the weak peak at about 449 cm À1 could be assigned to Mo-S vibration [33], and there was a peak at 923 cm À1 that corresponded to C-S deformation [58], which exhibited that the MoS 2 /rGO composites were successfully synthesized. Moreover, the peaks located at 1,026 and 1,112 cm À1 could be ascribed to the stretching modes of CÀO [59].…”

“…As shown in Fig. 2a, the MoS 2 displayed a series of strong and sharp peaks assigned to the (0 0 2), (1 0 0) and (1 1 0) reflections of MoS 2 flakes [33]. However, for MoS 2 / rGO, all the diffraction peaks were much lower and thinner than that of layered MoS 2 , especially for the (0 0 2) plane at 2h = 14.2°, suggesting that the crystallinity of the composites was much lower than that of pure MoS 2 .…”

Recent Advances in the Separation of Rare Earth Elements Using Mesoporous Hybrid Materials

“…As mentioned above, the conventional processes for the separation of REEs mainly include chemical precipitation, solvent extraction (or liquid‐liquid extraction, LLE), ion exchange, and solid‐liquid extraction, i. e., supported‐liquid extraction (SLE) and solid‐phase extraction (SPE) methods, which rely on the association between organic ligands and REEs . Ion exchange can be used to obtain REEs with purities higher than 99.9999 %; however, its large‐scale application is limited by the high cost .…”