Acid-Stable Magnetic Core–Shell Nanoparticles for the Separation of Rare Earths

Abstract

Core-shell Fe 3 O 4 @SiO 2 nanoparticles were prepared with a modified Stöber method and functionalized with N- [(3-trimethoxysilyl)propyl]ethylenediamine triacetic acid (TMS-EDTA).The synthesis was optimized to make core-shell nanoparticles with homogeneous and thin SiO 2 shells (4.8 ± 0.5 nm) around highly superparamagnetic Fe 3 O 4 cores (14.5 ± 3.0 nm). The coreshell Fe 3 O 4 @SiO 2 (TMS-EDTA) nanoparticles were then used for the extraction and separation of rare-earth ions. By comparing them with previously published results for Fe 3 O 4 (TMS-EDTA) and SiO 2 (TMS-EDTA) nanoparticles, it was clear that the core-shell nanoparticles combine the advantage of magnetic retrieval observed for Fe 3 O 4 (TMS-EDTA) nanoparticles, with the higher selectivity observed for SiO 2 (TMS-EDTA). The advantages of the SiO 2 shell include a lower specific weight and a larger grafting density compared to Fe 3 O 4 surfaces, but also the improved resistance to acidic environments required for the stripping of rare-earth ions.

Simultaneous adsorption of Li(I) and Rb(I) by dual crown ethers modified magnetic ion imprinting polymers

“…Unfortunately, the above powder‐like compounds are hard to collect after dispersed in a liquid system. To overcome such issues, magnetic polymeric nanoparticles are introduced to be the solid support . Magnetic polymeric nanoparticles is easily separated from a liquid system by using a magnetic field.…”

“…Magnetic polymeric nanoparticles is easily separated from a liquid system by using a magnetic field. Moreover, specific functional groups (such as ‐COOH, ‐OH, ‐NH 2 , crown ethers) grafted on the surface of magnetic polymeric nanoparticles can exert good capability to bind with target metal ions with high selectivity . In particular, crown ethers, which are composed of cyclic ethyleneglycol ((OCH 2 CH 2 ) n ), have selective binding ability with alkali metal ions, heavy metal ions and rare earth metal ions which possess similar size with the ring of them, due to their unique chemical structure.…”

Multifunctional iron oxide nanoparticles for biomedical applications

“…[5][6][7][8] Magnetic separation of rare earth ions, molecules or whole cells becomes possible by using this superparamagnetic core material. 9,10 In recent years, the synthesis of magnetite has been improved drastically by thermal decomposition methods. These rely mostly on organic iron precursors (oleate, acetylacetonate, …), which are decomposed at high temperatures, in presence of ligands that control the particles' shape and size.…”

Selective protein purification by PEG–IDA-functionalized iron oxide nanoparticles

“…Iron oxide particles (such as magnetite) are frequently used in hyperthermia, magnetic resonance imaging, optical or drug carrier experiments. 8,9 Many synthetic procedures have been reported to produce these nanoparticles with different shapes and sizes. 4 This largely facilitates their handling during functionalization procedures, while they still retain a high saturation magnetization, which enables a fast magnetic separation.…”