1,124 research outputs found
Ionic liquid technology for recovery and separation of rare earths
No full textEnd-of-life neodymium-iron-boron and samarium-cobalt permanent magnets, fluorescent lamps and metal hydride batteries are valuable secondary resources of rare earths. These resources are characterised by relatively small volumes, but high concentrations of rare earths [1]. On the other hand, industrial process residues such as bauxite residue (red mud) and phosphogypsum contain low concentrations of rare earths, but are available in huge volumes [2]. Recovery of rare earths from end-of-life consumer goods by urban mining and from industrial process residues by landfill mining can partly mitigate the supply risk of these critical metals. Efficient recovery of rare earths from these resources is a technological challenge, even though many pyrometallurgical and hydrometallurgical processes have been described in the literature. At KU Leuven (Belgium), we are developing new breakthrough technologies for recovery and separation of rare earths based on the use of ionic liquids. Ionic liquids are solvents that consist entirely of ions [3]. These solvents have properties that are quite different from those of conventional molecular organic solvents. Ionic liquids can find applications as lixiviants for selective leaching of rare earths from solid materials, as organic phase in solvent extraction processes for separation of rare earths, and as electrolytes for the electrodeposition of rare earths and alloys. During this talk, several new ionic liquid processes will be discussed: (1) recovery of yttrium and europium from end-of-life fluorescent lamps [4](2) recovery of rare earths from neodymium-iron-boron magnets [5], (3) separation of rare earths from transition metals by extraction with undiluted ionic liquids [6] (4) separation of rare earths by homogeneous liquid-liquid extraction (HLLE) [7] (5) efficient recovery of scandium from leachates of bauxite residue [8].
References
1 K. Binnemans, P.T. Jones, B. Blanpain, T. Van Gerven, Y. Yang, A. Walton, M. Buchert, J. Clean. Prod. 51, 1–22 (2013).
2 K. Binnemans, P.T. Jones, B. Blanpain, T. Van Gerven, Y. Pontikes, J. Clean. Prod. 99, 17–38 (2015).
3 K. Binnemans, Chem. Rev. 107, 2592-2614 (2007).
4 D. Dupont and K. Binnemans, Green Chem. 17, 856–868 (2015).
5 D. Dupont, K. Binnemans, Green Chem. 17, 2150–2163 (2015).
6 T. Vander Hoogerstraete, S. Wellens, K. Verachtert, K. Binnemans, Green Chem. 15, 919–927 (2013).
7 T. Vander Hoogerstraete, B. Onghena, K. Binnemans, J. Phys. Chem. Lett. 4, 659−1663
(2013).
8 B. Onghena, K. Binnemans, Ind. Eng. Chem. Res. 54, 1887–1898 (2015).status: Publishe
Luminescence of lanthanidomesogens in the liquid crystal state
No full textA lanthanide center can add unique magnetic or spectroscopic properties to a liquid crystal [1,2]. The first examples of lanthanide-containing liquid crystals (lanthanidomesogens) had rather high transition temperatures (>100 °C) and low thermal stability at these elevated temperatures. These were major drawbacks that hampered the study of the physical properties of these materials. It is especially difficult to observe light emission (luminescence) at high temperatures because of the strong tendency of the excited states to de-activate via non-radiative transitions. However, careful design of lanthanidomesogens on the basis of previously gained experience enables at present to obtain lanthanide complexes that are liquid-crystalline at very moderate temperatures or even at room temperature. Thanks to this recent progress, luminescence studies of lanthanidomesogens in the liquid crystal state are starting to appear in the scientific literature [3]. This lecture gives an overview of these recent developments, with an emphasis on the work performed by the Leuven group. A fascinating property of these materials is the ability to observe linearly polarized emission [4].
[1] K. Binnemans, C. Görller-Walrand, Chem. Rev., 2002, 102, 2303.
[2] C. Piguet, J.-C. G. Bünzli, B. Donnio, D. Guillon, Chem. Commun., 2006, 3755.
[3] K. Binnemans, J. Mater. Chem., 2009, DOI: 10.1039/B811373D.
[4] Y.G. Galyametdinov, A.A. Knyazev, V.I. Dzhabarov, T. Cardinaels, K. Driesen, C. Görller-Walrand, K. Binnemans, Adv. Mater., 2008, 20, 252.status: Publishe
Lanthanides and actinides in ionic liquids
No full textThis lecture gives an overview of the research possibilities offered by combining f-elements (lanthanides and actinides) with ionic liquids [1] Many ionic liquids are solvents with weakly coordinating anions. Solvation of lanthanide and actinide ions in these solvents is different from what is observed in conventional organic solvents and water. The poorly solvating behavior can also lead to the formation of coordination compounds with low coordination numbers. The solvation of f-elements can be simulated by molecular dynamics simulations with explicit representation of the solvent, or can be directly probed by spectroscopic methods. Ionic liquids turn out to be a promising solvent for near-infrared emitting lanthanide complexes [2]. It is often mentioned that one of the main advantages of ionic liquids is their resistance to strongly oxidizing or reducing agents, i.e. ionic liquids have a large electrochemical window. However, not all ionic liquids are suitable for study of the electrochemical properties and electrodeposition of f-elements. The metals of the lanthanides and actinides are very electropositive elements, and they will reduce imidazolium cations. More resistant against reduction are quaternary ammonium and phosphonium cations. Ionic liquids offer a large potential in the field of processing of spent nuclear fuel elements. The advantage is that the processing can be carried out at much lower temperature in ionic liquids than in inorganic molten salts. This reduces not only the energy cost, but also increases the safety. The fact that several ionic liquids strongly absorb neutrons (especially boron- and chlorine-containing ionic liquids), reduces the risk of criticality accidents. The study of metal-catalyzed organic reactions in ionic liquid media is a very popular research theme. It is therefore not surprising that lanthanide-mediated organic reactions are being performed in ionic liquids as well. The possibility to recycle the lanthanide catalyst that is immobilized in the ionic liquid and the possibility of easy product separation have stimulated researchers to work in this field. However, in only a few cases the use of (expensive) ionic liquids can be justified by the higher reactivity or selectivity. Cerium-mediated oxidation reactions in ionic liquids will be discussed [3]. The combination of lanthanides and ionic liquids can lead to new types of advanced materials (luminescent or magnetic liquid crystals, ionogels, nanoparticles, …) [4,5]. Anionic lanthanide complexes can be the constituent of metal-containing ionic liquids [6].
References:
[1] K. Binnemans, Chem. Rev. 107 (2007) in press.
[2] S. Arenz, A. Babai, K. Binnemans, K. Driesen, R. Giernoth, A.V. Mudring, P. Nockemann, Chem. Phys. Lett. 402 (2005) 75-79.
[3] H. Mehdi, A. Bodor, D. Lantos, I.T. Horváth, D.E. De Vos, K. Binnemans,
J. Org. Chem. 72 (2007) 517-524.
[4] K. Binnemans, Chem. Rev. 105 (2005) 4148-4204.
[5] K. Lunstroot, K. Driesen, P. Nockemann, C. Görller-Walrand, K. Binnemans, S. Bellayer, J. Le Bideau, A. Vioux, Chem. Mater. 18 (2006) 5711-5715.
[6] P. Nockemann, B. Thijs, N. Postelmans, K. Van Hecke, L. Van Meervelt, K. Binnemans, J. Am. Chem. Soc. 128 (2006) 13658-13659.sponsorship: F.W.O.-Flanders (project G.0508.07)
K.U.Leuven (project GOA 08/05 and project IDO/05/005)status: Publishe
Synthesis of polyaramids in γ-valerolactone-based organic electrolyte solutions
No full textsponsorship: This research was funded by a doctoral (PhD) strategic basic research grant of the Research Foundation Flanders (FWO) to Jonas Winters (1S12717N). The help of Jakob Busse in the design and building of the 3D-printed spinning setup is greatly acknowledged. (Research Foundation Flanders (FWO)|1S12717N)status: Publishe
The Balance Problem and its Relevance to Recycling of Rare Earths
No full textThe balance between the demand by the economic markets and the natural abundances of the rare-earths elements (REEs) in ores is a major problem for manufacturers of these elements. This is the balance problem.1 The ideal situation is a perfect match between the demand and production of REEs, so that there are no surpluses of any of the REEs. This would result in the lowest market price for any of the REEs, because the production costs are shared by all the elements. Neodymium is high in demand for NdFeB magnets and this results in an overproduction of other REEs (e.g. cerium). The industry has to find new applications for REEs that are available in excess, or to search for substitutions for REEs that have limited availability and that are high in demand. REE markets are permanently changing. Diversification of the REE ores can be a partial solution As long as the rare earths were used as mixtures the balance problem was not existing. So far, the balance problem has mainly been considered from the viewpoint of REE ores, and not from the viewpoint of REE recycling. It will be shown that REE recycling is not only of importance for securing the REE supply, but that is also offers a partial solution for the balance problem.2,3
References
(1) P. Falconnet, J. Less-Common Met. 111, 9 (1985).
(2) K. Binnemans et al., J. Clean. Prod. 51, 1-22 (2013).
(3) K. Binnemans et al., JOM 65, 846–848 (2013).status: Publishe
Luminescence of metallomesogens in the liquid crystal state
No full textA metal center can add unique magnetic, spectroscopic or redox properties to a liquid crystal. Whereas the first examples of metal-containing liquid crystals (metallomesogens) mimicked the rodlike or disklike shape of the conventional organic liquid crystals, it gradually became clear that mesomorphism can also be observed for other coordination geometries than linear or square-planar coordination. For most of the metallic elements, at least one liquid-crystalline metal complex has been described in the literature. However, the high transition temperatures (>100 °C) and low thermal stability at these elevated temperatures of metallomesogens are major drawbacks that hamper the study of the physical properties of these materials. It is especially difficult to observe light emission (luminescence) at high temperatures because of the strong tendency of the excited states to de-activate via non-radiative transitions. Therefore most of the luminescence studies on metallomesogens that have been performed so far have been restricted to samples in the solid state or dissolved in organic solvents. However, careful design of metallomesogens on the basis of previously gained experience enables at present to obtain metal complexes that are liquid-crystalline at very moderate temperatures or even at room temperature. Thanks to this recent progress, luminescence studies of metallomesogens in the liquid crystal state are starting to appear in the scientific literature [1].
Luminescence in the liquid crystal state has been observed for metallomesogens incorporating lanthanide(III), gold(I), silver(I), copper(I) or zinc(II) ions. It should be noted that most of the emissive excited states in metallomesogens are not metal-centered, the luminescence by the trivalent lanthanide ions being the exception. As a consequence, the luminescence properties of the metallomesogens containing d-block elements are more strongly affected by the intramolecular interactions in the mesophase than those of the lanthanidomesogens. The study of the luminescence of metallomesogens in the liquid crystal state can give valuable fundamental insight in the photophysics of ordered metal-containing systems.
Another approach to obtain luminescent metal-containing liquid crystals is by dissolving a luminescent metal complex in a suitable liquid-crystal host matrix. The advantage of this method is that the luminescence and mesomorphic properties can independently be optimized.. A fascinating property of aligned mesophases of luminescent metal complexes is the ability to observe linearly polarized emission. This was first observed for nematogenic lanthanide complexes based on b-diketonate ligands [2].
References
[1] K. Binnemans, J. Mater. Chem. ,2009, DOI: 10.1039/b811373d
[2] Y.G. Galyametdinov, A.A. Knyazev, V.I. Dzhabarov, T. Cardinaels, K. Driesen, C. Görller-Walrand, K. Binnemans, Adv. Mater., 2008, 20, 252.status: Publishe
Is REE recycling the solution for the balance problem?
No full textInvited lecture by Koen Binnemansstatus: Publishe
Recovery of rare earths from industrial waste residues: a concise review
No full textBetween 2000 and 2012, China has been producing more than 95% of the annual world supply of the rare-earth elements (REEs). Due to large and increasing domestic demands, China has introduced tight export quota for rare earths. These quota cause rare-earth supply risks outside China, but they also stimulate other countries to look for other rare-earth resources and to develop their own rare-earth industry. The shortage of rare earths stimulates the prospection for new rare-earth deposits, the development of new mines and the re-opening of older mines that had been closed in the past because of economic reasons. The supply risk of rare earths also provides a boost to the research on the recycling of rare earths from End-of-Life consumer goods. Up to now, rare-earth recycling (research) has focused on relatively small volumes of End-of-Life waste with a high REE content. However, rare-earths are also present in lower concentrations in a multitude of industrial residues. This review, therefore, discusses the possibilities to recover rare earths from residues such as pyrometallurgical slags, bauxite residue (red mud), phosphogypsum, mine tailings and waste water. All these waste streams have in common that they only have low REE concentrations, but are available in very large volumes. This implies that these industrial waste streams could provide significant amounts of rare earths, provided
efficient recycling flow sheets can be developed.status: Publishe
Gamma radiation effects on AG MP-50 cation exchange resin and sulfonated activated carbon for bismuth-213 separation
No full textMedical 225Ac/213Bi radionuclide generators are designed to provide a local supply of the short-lived 213Bi for cancer treatment. However, radiation-induced damage to the sorbents commonly used in such radionuclide generators remains a major concern. In this study, the effects of gamma radiation on AG MP-50 cation exchange resin and sulfonated activated carbon (SAC) were studied by analyzing the changes in the morphological characteristics, functional groups, and the La3+/Bi3+ sorption performance, with La3+ being a suitable non-radioactive substitute for Ac3+. The surface sulfonic acid groups of AG MP-50 resin suffered from severe radiation-induced degradation, while the particle morphology was changed markedly after being exposed to absorbed doses of approximately 11 MGy. As a result, the sorption performance of irradiated AG MP-50 for La3+ and Bi3+ was significantly decreased with increasing absorbed doses. In contrast, no apparent changes in acquired morphological characteristics were observed for pristine and irradiated SAC based on SEM and XRD characterization. The surface oxygen content (e.g., O-C00000000000000000000000000000000111111110000000011111111000000000000000000000000O) of irradiated SAC increased for an absorbed dose of 11 MGy due to free radical-induced oxidation. The sorption performance of pristine and irradiated SAC materials for La3+ and Bi3+ remained generally the same at pH values of 1 and 2. Furthermore, the applicability of AG MP-50 and SAC in the 225Ac/213Bi generators was illustrated in terms of their radiolytic stability. This study provides further evidence for the practical implementation of both AG MP-50 and SAC in 225Ac/213Bi radionuclide generators. New sulfonated activated carbon (SAC) materials were designed and synthesized for use in medical 225Ac/213Bi radionuclide generators. Their stability towards gamma radiation was assessed and compared with the commonly used AG MP-50 resin.The SCK CEN Academy and VITO are acknowledged for funding. Samuel Eyley and Wim Thielemans also acknowledge nancial support from KU Leuven (grant C14/18/061) and Research Foundation Flanders-FWO (G0A1219N). Peter Adriaensens gratefully acknowledges the nancial support by Hasselt University and the Research Foundation Flanders (FWO Vlaanderen) via the Hercules project AUHL/15/2-GOH3816N. Furthermore, the authors would like to acknowledge the technical assistance of Prisca Verheyen (ICP-MS), Ken Verguts (material irradiation), Myrjam Mertens (XRD), Hilde Lenaerts & Kaimin Zhang & Vera Meynen (DRIFT), and Kemps Raymond (SEM)
Heteropolynuclear metallomesogens
No full textMixed f-d metallomesogens are an intriguing new class of materials, since they combine specific magnetic interactions of f-d coordination compounds with the properties of liquid crystals. Furthermore, from a materials processing point of view, such f-d metallomesogens could be advantageous because of the strong tendency of the lanthanide-based metallomesogens to form a glassy state on cooling rather than to crystallise, and thus giving the possibility to freeze-in the mesomorphic order, whereas common non-mesomorphic f-d coordination complexes are obtained as crystalline powders. In order to obtain these heteropolynuclear f-d metallomesogens, our approach consisted of modifying the structures of previously described non-mesomorphic f-d complexes in such a way that a sufficient structural anisotropy was obtained for the formation of mesophases.
We describe in this contribution the synthesis and characterisation of heteropolynuclear metallomesogens containing both a transition metal ion and a lanthanide ion [1]. We synthesised adducts between a mesomorphic Cu(salen) complex (salen = 2,2’-N,N’-bis(salicylidene) ethylenediamine) and a lanthanide nitrate. Different stoichiometries were found, depending on the lanthanide ion: [Ln(NO3)3{Cu(salen)}2], for Ln = La – Nd, and [Ln(NO3)3Cu(salen)] for Ln = Sm – Lu. This stoichiometry corresponds to that of similar unsubstituted complexes [2]. The compounds exhibit a wide temperature-range hexagonal columnar mesophase (ColH) with rather low melting temperatures. Although the clearing point could be observed for the parent Cu(salen) complex, the mixed f-d complexes decomposed before clearing. The copper ion can be replaced by a nickel ion. By reducing the number of terminal alkyl chains, we were able to obtain f-d metallomesogens with smectic mesomorphism (smectic A phase)
References:
[1] K. Binnemans, K. Lodewyckx, B. Donnio and D. Guillon, Chem. Eur. J. 2002, 8, 1101.
[2] M.L. Kahn, T.M. Rajendiran, Y. Jeannin, C. Mathonière, O. Kahn, C.R. Acad. Sci, II C 2000, 3, 131.status: Publishe
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