title: Unusual seeding mechanism for enhanced performance in solid-phase magnetic extraction of Rare Earth Elements.
abstract: Due to the increasing demand of Rare Earth Elements (REE or RE), new and more efficient techniques for their extraction are necessary, suitable for both mining and recycling processes. Current techniques such as solvent extraction or solid adsorbents entail drawbacks such as using big volumes of harmful solvents or limited capacity. Hybrid nanoadsorbents based on SiO2and highly stable γ-Fe2O3-SiO2nanoparticles, proved recently to be very attractive for adsorption of REE, yet not being the absolute key to solve the problem. In the present work, we introduce a highly appealing new approach in which the nanoparticles, rather than behaving as adsorbent materials, perform as inducers of crystallization for the REE in the form of hydroxides, allowing their facile and practically total removal from solution. This induced crystallization is achieved by tuning the pH, offering an uptake efficiency more than 20 times higher than previously reported (up to 900 mg RE3+/g vs. 40 mg RE3+/g). The obtained phases were characterized by SEM-EDS, TEM, STEM and EFTEM and13C and29Si solid state NMR. Magnetic studies showed that the materials possessed enough magnetic properties to be easily removed by a magnet, opening ways for an efficient and industrially applicable separation technique.
authors.affiliation: Department of Chemistry and Biotechnology, Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Box 7015, 75007 Uppsala, Sweden.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Polido Legaria
authors.affiliation: Department of Chemistry CICECO, University of Aveiro, Aveiro, Portugal.
authors.forename: Joao
authors.initials: J
authors.lastname: Rocha
authors.affiliation: Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden.
authors.forename: Cheuk-Wai
authors.initials: CW
authors.lastname: Tai
authors.affiliation: Department of Chemistry and Biotechnology, Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Box 7015, 75007 Uppsala, Sweden.
authors.forename: Vadim G
authors.initials: VG
authors.lastname: Kessler
authors.affiliation: Department of Chemistry and Biotechnology, Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Box 7015, 75007 Uppsala, Sweden.
authors.forename: Gulaim A
authors.initials: GA
authors.lastname: Seisenbaeva
mesh_terms: D000327:Adsorption; D002412:Cations / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008674:Metals, Rare Earth / Q000737:chemistry* / Q000302:isolation & purification*; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D012822:Silicon Dioxide / Q000737:chemistry; D052616:Solid Phase Extraction; D012997:Solvents / Q000737:chemistry
chemical_list: D002412:Cations; D008674:Metals, Rare Earth; D012997:Solvents; D012822:Silicon Dioxide