Search

Environmental concerns and lack of space suggest that the management of bauxite residue needs to be re-adressed. The utilization of the residue has thus become a topic high on the agenda for both academia and industry, yet, up to date, it is only rarely used. Nonetheless, recovery of rare earth elements (REEs) with or without other metals from bauxite residue, and utilization of the left-over residue in other applications like building materials may be a viable alternative to storage. Hence, different processes developed by the authors for recovery of REEs and other metals from bauxite residue were compared. In this study, preliminary energy and cost analyses were carried out to assess the feasibility of the processes. These analyses show that the combination of alkali roasting-smelting-quenching-leaching is a promising process for the treatment of bauxite residue and that it is justified to study this process at a pilot scale.

Polycrystalline U3O7 powder was synthesized by oxidation of UO2 powder under controlled conditions using in situ thermal analysis, and by heat treatment in a tubular furnace. The O/U ratio of the U3O7 phase was measured as 2.34 ± 0.01. The crystal structure was assessed from X-ray diffraction (XRD) and selected-area electron diffraction (SAED) data. Similar to U4O9−e (more precisely U64O143), U3O7 exhibits a long-range ordered structure, which is closely related to the fluorite-type arrangement of UO2. Cations remain arranged identical to that in the fluorite structure, and excess anions form distorted cuboctahedral oxygen clusters, which periodically replace the fluorite anion arrangement. The structure can be described in an expanded unit cell containing 15 fluorite-like subcells (U15O35), and spanned by basis vectors A = ap – 2bp, B = −2ap + bp, and C = 3cp (lattice parameters of the subcell are ap = bp = 538.00 ± 0.02 pm and cp = 554.90 ± 0.02 pm; cp/ap = 1.031). The arrangement of cuboctahedra in U3O...

The long-term storage of bauxite residue (red mud) is harmful to the environment and the tailing ponds also cover large areas. At the moment there is no large-scale utilization of bauxite residue. However, some bauxite residues contain considerable concentrations of rare-earth elements (REEs) and the recovery of these REEs together with(out) other metals and utilization of the generated residue in other applications (e.g., building materials) can solve the storage problem of bauxite residue. This paper reviews the recovery of REEs, possibly alongside other valuable metals, from bauxite residue. REEs can be recovered from bauxite residue by direct leaching or by smelting followed by leaching. The main disadvantages of direct acid leaching are the consumption of large amounts of acid for neutralization, the handling of large volumes of effluents, and the difficulty in using the bauxite residue after leaching. Recovery of iron prior to leaching can improve the economics of the process. However, high alumina in the bauxite residue increases the flux and acid consumption. Therefore, alumina needs to be removed by alkali roasting prior to smelting in order to decrease the flux and acid consumption. The alkali roasting–smelting–leaching process allows recovery of aluminum, iron, titanium, and REEs from bauxite residue. The residue generated in this process can be used in building materials and cementitious binders. Other processes with commercial potential are the Orbite, the pressure leaching, and the acid baking processes.

Fe and N dual-doped mesoporous carbon catalyst demonstrated superior catalytic activity than Pt catalyst for both oxygen reduction and oxidation reactions in alkaline electrolyte. The catalyst was synthesized through a novel simple sublimation and capillary assisted nanocasting method. Using the method, multiple transition metal and nitrogen dual-doped mesoporous carbon electrocatalysts were also successfully made. It was believed that the excellent catalytic activity was resulted from the synergistic effects of highly active metal-nitrogen species, mesoporous structure, large interfacial surface and excellent conductivity. The present synthetic strategy offers a new insight into preparation of heteroatom-doped electrocatalysts with promising applications in metal-air batteries, fuel cells, and supercapacitors as well.

A solvent extraction system based on the ionic liquid tricaprylmethylammonium nitrate, [A336][NO3], has been investigated for separation of mixtures of rare earth elements (REE) at high total REE concentrations (up to 2 M). The chelating agent EDTA was added to the aqueous nitrate feed solution to increase the separation factors (SFs). This improvement of the SFs is based on the fact that [A336][NO3] extracts the light REE (LREE) stronger than the heavy REE (HREE), whereas a chelating agent forms more stable complexes with the HREE than with the LREE. The combination of these two effects makes that the LREE are even more efficiently extracted than in the absence of a chelating agent. The most efficient separation of the LREE La–Nd from the other REE was obtained using a total initial REE concentration of 1 M, an EDTA concentration of 0.2 M, and a total nitrate concentration of 11 M. Stripping of the extracted REE from the ionic liquid phase could be done using water. ispartof: Journal of Sustainable Metallurgy vol:3 issue:1 pages:73-78 status: published

Bauxite residue (red mud) that is generated from karst bauxite ores is rich in rare-earth elements (REEs). The REEs can be recovered from bauxite residue by direct acid leaching but the extraction yields are generally low. The extraction yields can be increased by increasing the acid concentration but this will increase the dissolution of iron as well. Large amounts of iron in the leach solution create problems in the further recovery processes. Therefore, a combined sulfation–roasting–leaching process was developed to selectively leach the REEs while leaving iron undissolved in the residue. In this process bauxite residue was mixed with water and concentrated H2SO4 followed by drying, roasting and then leaching of the roasted product with water. Most of the oxides were converted to their respective sulfates during the sulfation process. During subsequent roasting, unstable sulfates (mainly iron(III) sulfate) decompose to their respective oxides. Rare-earth sulfates, on the other hand, are stable during roasting and dissolve during water leaching, leaving the iron oxides in the residue. The effect of the roasting temperature, roasting time and amount of acid on leaching of the different elements was studied. Decreasing the roasting temperature increased the dissolution of the REEs, but also that of iron and aluminum. Increasing the amount of acid led to higher REEs extraction. Acid to bauxite residue mass ratio beyond 0.75 at 650 °C increases the iron and aluminum dissolution due to increase in the iron(III) and aluminum sulfate amounts. The extraction of REEs slightly increased (

Replacing conventional solvents by ionic liquids is often suggested as a possible route to greener industrial processes. However, ionic liquids are typically petroleum-derived. This critical perspective discusses the syntheses, applications and limitations of biobased ionic liquids synthesized from amino acids, carbohydrates, lignin and other renewable sources. The practical aspects of applying such ionic liquids in lignocellulose processing, as a reaction solvent, organocatalyst or as metal extraction medium are highlighted.

The nanostructure and phase evolution in low-temperature oxidized (40-250 °C), fine UO2 powders (200 nm) have been investigated by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The extent of oxidation was also measured via in situ thermogravimetric analysis. The oxidation of fine powders was found to proceed differently as compared to oxidation of coarse-grained UO2. No discrete surface oxide layer was observed and no U3O8 was formed, despite the high degree of oxidation (up to O/U = 2.45). Instead, nanosized (5-15 nm) amorphous nuclei (interpreted as amorphous UO3), unmodulated and modulated U4O9, and a continuous range of U3O7-z phases with varying tetragonal distortion (c/a1) were observed. Oxidation involves formation of higher uranium oxides in nanodomains near the grain surface which, initially, have a disordered defect structure ("disordered U4O9"). As oxidation progresses, domain growth increases and the long-period modulated structure of U4O9 develops ("ordered U4O9"). A similar mechanism is understood to happen also in U3O7-z.

This journal is © 2016 The Royal Society of Chemistry. The influence of irradiance on the photochemical reduction of europium(iii) to europium(ii) is studied. It is known that europium removal from various rare-earth mixtures is feasible by means of photochemical reduction followed by precipitation, but the effect of the nature of the light source has not been investigated in detail yet. It is shown that irradiance rather than electrical power is a key parameter to characterize light sources used for photochemical experiments and to compare experiments with set-ups using different light sources. The irradiance of a light source, expressed in Watts per unit of area (mW cm-2), has a crucial impact on the photochemical reduction of europium(iii) in aqueous media, in particular on the illumination time needed for europium removal from the solution. The influence of the irradiance on the induction time (a period with no or little europium removal in the first illumination hours), the europium removal rate after the induction time, the overall removal time and the time needed to remove 50% of the initial europium content from the solution (t50%) is studied. It is observed that higher irradiances result in shorter induction times, faster europium removal rates, lower t50% and hence shorter overall illumination times. The threshold irradiance to obtain 50% europium removal in 36 hours was found to be 2.7 mW cm-2, with an induction time of 28 hours. The residual europium content in all samples was lower than 2.5%, resulting in removal efficiencies of over 97.5%. This residual europium content seems to be increasing when the relative irradiance related to the back-oxidation increases, although this correlation cannot be fully explained yet. This work gives new insights that can be used for the photochemical recycling of europium from end-of-life red phosphors in compact fluorescent lamps (CFLs). crosscheck: This document is CrossCheck deposited copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported Licence (CC BY-NC 3.0) history: Received 19 January 2016; Accepted 26 April 2016; Accepted Manuscript published 26 April 2016; Advance Article published 11 May 2016; Version of Record published 21 July 2016 ispartof: Green Chemistry vol:18 issue:15 pages:4198-4204 status: published

Sulfamic acid (NH3-SO3) is an acidic zwitterion with many applications. N-Alkylated derivatives are introduced, which can be used as a new class of metal extractants R2NH-SO3 and as new super-acidic ionic liquids [R2NH-SO3H][Tf2N]. The synthesis, properties and novel applications of this versatile platform are discussed.

Aqueous waste streams of the metallurgical industry often contain considerable concentrations of metal salts. Previous research showed that the metal chloride salts of zinc(ii), manganese(ii) and iron(iii) can be recovered by solvent extraction using a sustainable and renewable fatty acid based ionic liquid as the extractant. In this paper, the extraction mechanism of Zn(ii), Co(ii) and Ni(ii) from chloride media has been studied systematically. The metal extraction performances of the precursors, sodium oleate and tetraoctylammonium chloride, were compared to the extraction performance of the ionic liquid tetraoctylammonium oleate. Slope analysis experiments were performed to determine the number of ionic liquid molecules involved in the extraction. The experimental data showed that Co(ii) and Ni(ii) were extracted in the pH range from 6 to 8 by the formation of negatively charged metal carboxylate complexes with tetraalkylammonium counter ions. In contrast, Zn(ii) gets extracted as a mixed metal chloride carboxylate anionic complex with tetraalkylammonium counter ions. This extraction mechanism was supported by EXAFS measurements.

Imidazolium ionic liquids were synthesized from readily available molecules: aldehydes, 1,2-carbonyl components, alkyl amines and acids in a halogen-free procedure. Since the use of enolisable carbonyl functions is not compatible with the modified Debus–Radziszewski reaction, symmetrical 1,3-dialkylimidazolium ionic liquids were made. The use of strong acids, like sulfuric acid, leads to protonation of the amine, low yields and side products that are difficult to remove. Changing the acid in the synthesis to acetic acid greatly improved the isolated yield and produced pure imidazolium acetate ionic liquids. From these imidazolium acetate compounds, many other ionic liquids could be prepared using different metathesis strategies. These strategies were dependent on the acidity of the conjugate acid of the anion, the acid volatility and the hydrophilicity of the used reagents and resulting ionic liquid. The following anions were introduced: bis(trifluoromethylsulfonyl)imide ([Tf2N]−), p-toluenesulfonate (tosylate, [TsO]−), bis(2-ethylhexyl)phosphate ([DEHP]−) and nitrate ([NO3]−). The impact of the different anions on the properties of the ionic liquids was investigated. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: The accepted version of this article will be made freely available after a 12 month embargo period history: Received 30 October 2015; Accepted 13 January 2016; Accepted Manuscript published 15 January 2016; Version of Record published 21 January 2016 ispartof: RSC Advances vol:6 issue:11 pages:8848-8859 status: published

The first redox flow battery (RFB), based on the all-copper liquid metal salt [Cu(MeCN)4][Tf2N], is presented. Liquid metal salts (LMS) are a new type of ionic liquid that functions both as solvent and electrolyte. Non-aqueous electrolytes have advantages over water-based solutions, such as a larger electrochemical window and large thermal stability. The proof-of-concept is given that LMSs can be used as the electrolyte in RFBs. The main advantage of [Cu(MeCN)4][Tf2N] is the high copper concentration, and thus high charge and energy densities of 300 kC l(-1) and 75 W h l(-1) respectively, since the copper(i) ions form an integral part of the electrolyte. A Coulombic efficiency up to 85% could be reached.

A sustainable solvent extraction process for purification of indium has been developed from a chloride aqueous feed solution using the ionic liquids Cyphos® IL 101 and Aliquat® 336. The high affinity of indium(III) for the ionic liquid phase gave extraction percentages above 95% over the HCl concentration range from 0.5 to 12 M. Attention was paid to the loading capacity of the ionic liquid phase and the kinetics of the extraction process. An extraction mechanism was proposed based on the relationship between the viscosity of the ionic liquid phase and the loading with indium(III) ions. Even for loadings as high as 100 g L−1, equilibrium was reached within 10 min. Due to the very high distribution ratio for indium(III), stripping of indium(III) from the ionic liquid phase was very difficult with water or acid solutions. However, indium could conveniently be recovered as In(OH)3 by precipitation stripping with a NaOH solution. Precipitation stripping has the advantage that no ionic liquid components are lost to the aqueous phase and that the ionic liquid is regenerated for direct re-use. The extraction of some metal ions that are commonly found as impurities in industrial indium process solutions, i.e. cadmium(II), copper(II), iron(III), manganese(II), nickel(II), tin(IV) and zinc(II), has been investigated. The distribution ratios for the different metal ions show that indium(III) can be purified efficiently by a combination of extraction, scrubbing and stripping stages. This new ionic liquid process avoids the use of volatile organic solvents. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0) history: Received 29 February 2016; Accepted 9 May 2016; Accepted Manuscript published 9 May 2016; Advance Article published 17 May 2016; Version of Record published 11 July 2016 ispartof: Green Chemistry vol:18 issue:14 pages:4116-4127 status: published

Antimony is becoming an increasingly critical element as the supply-demand gap is expected to exceed 10% over the period 2015–2020. Antimony production is primarily concentrated in China (90%) and as the industrial demand for this metal surges, attention has to turn towards the recovery of antimony from (industrial) waste residues and end-of-life products in order to guarantee a sustainable supply of antimony. Although lamp phosphor waste is usually considered as a source of rare earths, it also contains significant amounts of antimony in the form of the white halophosphate phosphor (Ca,Sr)5(PO4)3(Cl,F):Sb3+,Mn2+ (HALO). HALO phosphor readily dissolves in dilute acidic conditions, making antimony far more accessible than in the main production route which is the energy intensive processing of stibnite ore (Sb2S3). HALO makes up 50 wt% of the lamp phosphor waste, but it has been systematically overlooked and treated as an undesired residue in the efforts to recover rare earths from lamp phosphor waste. In this paper, the feasibility of antimony recovery is discussed and an efficient process is proposed. The HALO phosphor is first dissolved in dilute HCl at room temperature, followed by a selective extraction of antimony with the ionic liquid Aliquat® 336. The remaining leachate is valorized as apatite which is a feed for the phosphate and fertilizer industry. A zero-waste valorization approach was followed, meaning that no residue or waste was accepted and that all the elements were converted into useful products. This paper thus emphasizes the potential of lamp phosphor waste as a secondary source of antimony and describes a sustainable process to recover it. The process can be integrated in lamp phosphor recycling schemes aimed at recovering rare earths. ispartof: Green Chemistry vol:18 issue:1 pages:176-185 status: published

Manganese oxide was deposited from a non-aqueous solution, dimethyl sulfoxide (DMSO), via the reduction of dissolved oxygen. The formed superoxide radical ion (O2c) reacts rapidly with the manganese ions forming a smooth and thin film (80 nm) of manganese oxide. From an in situ EQCM study, it could be concluded that MnO2 was the most probable oxide which was deposited at an average growth rate of 0.049 mg s1 or 0.077 nm s1 . Since the direct deposition of a phase pure MnO2 layer was not confirmed by XRD, it is more likely that a variety of manganese oxides has been deposited during the electro-precipitation reaction and thus further optimization or post-treatments are required to obtain an active manganese oxide layer for thin film deposits. The key property of this new deposition technique is the self-limiting behavior, proven by rotating ring-disk electrode experiments. This is crucial to electrodeposit thin films conformally on high aspect ratio structures for 3D all-solid-state lithium-ion batteries or supercapacitors. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Felix Mattelaer (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported Licence (CC BY-NC 3.0) history: Received 26 April 2016; Accepted 4 August 2016; Accepted Manuscript published 4 August 2016; Advance Article published 17 August 2016; Version of Record published 30 August 2016 ispartof: Journal of Materials Chemistry A vol:4 issue:35 pages:13555-13562 status: published

Ternary copper-zinc-tin coatings have been prepared by a one-step electrodeposition on molybdenum sputtered soda-lime glass (SLG) (20 y 20 mm 2 ) from an aqueous pyrophosphate electrolyte at room temperature. The plating bath contains copper(II), zinc(II), tin(II) and potassium pyrophosphate at pH = 10. The influence of pyrophosphate as a complexing agent is characterized by speciation simulation, cyclic voltammetry and linear sweep voltammetry. The electrolyte and deposition conditions were adjusted to deposit ternary coatings with the appropriate copper-poor and zinc-rich composition (Cu/(Zn + Sn) = 0.89 and Zn/Sn = 1.04), making them suitable for preparing kesterite absorber films for photovoltaic applications. The composition is influenced by variation of the deposition potential, pH, temperature, composition of the electrolyte and control of the mass transport. The morphology, composition and structure of the as-deposited and selenized films were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray diffraction (XRD). Dense, closed, homogeneous films of ternary copper-zinc-tin alloys with a mirror-bright gray appearance were deposited from the pyrophosphate electrolyte. After selenization, the coatings were matte gray and consisted of micrometer sized grains of pure CZTSe reaching over the complete thickness with only a few voids near the molybdenum back contact.

The vibrating-nozzle technology is very interesting to very easily and very rapidly produce industrial amounts of functional microspheres. The technology was used to make hybrid alginate–silica microspheres by droplet coagulation. The microspheres were formed starting from suspensions of sodium alginate, and coagulation occurred in an aqueous solution of calcium ions. To enhance the mechanical properties of the alginate raw material, it was combined with two different silica sources: tetramethyl orthosilicate (TMOS) and commercial silica powder. The two different batches of alginate–silica microspheres were fully compared with regard to their morphology, composition, shrinking behavior, and stability in acidic conditions. It was shown that the incorporation of an inorganic matrix resulted in a material with a better stabilized porous structure and a higher resistance in an acidic environment. Both are important when functional particles are designed to be used for adsorption of metal ions, either as a stirred suspension or as a stationary phase in a chromatographic column. A study of the adsorption performance was conducted in batch mode for neodymium(III), a representative element for the group of critical rare-earth elements. The effect of stripping (desorption) on the adsorption performance and reusability was also investigated. The functional alginate–silica microspheres show a sustainable character. ispartof: Industrial & Engineering Chemistry Research vol:54 issue:51 pages:12836-12846 status: published

The lattice deformations in two doped fluorite systems, (U1−xGdx)O2.00 and (Th1−xGdx)O2−x/2, have been reassessed by precise X-ray and electron diffraction investigations and the results were interpreted using the Bond Valence Sum (BVS) approach. For the (U1−xGdx)O2.00 system, the experimental findings and theoretical assessment confirm earlier work: the lattice keeps its fluorite structure with a unit cell parameter that contracts linearly with dopant concentration. The lattice contraction in the (Th1−xGdx)O2−x/2 system has for the first time been analyzed up to the solubility limit. Similar as for (U1−xGdx)O2.00, the (Th1−xGdx)O2−x/2 solid solution contracts linearly as a function of dopant concentration but additionally, it develops a superstructure which is closely related to the parent fluorite structure. An excess anion bixbyite trial model is proposed to describe this superstructure.

Summarization: With an increasing number of low-grade primary ores starting to be cost-effectively mined, we are at the verge of mining a myriad of low-grade primary and secondary mineral materials. At the same time, mining practices and mineral waste recycling are both evolving towards sustainable near-zero-waste processing of low-grade resources within a circular economy that requires a shift in business models, policies and improvements in process technologies. This review discusses the evolution towards low-grade primary ore and secondary raw material mining that will allow for sufficient supply of critical raw materials as well as base metals. Seven low-grade ores, including primary (Greek and Polish laterites) and secondary (fayalitic slags, jarosite and goethite sludges, zinc rich waste treatment sludge and chromium-rich neutralisation sludge) raw materials are discussed as typical examples for Europe. In order to treat diverse and complex low-grade ores efficiently, the use of a new metallurgical systems toolbox is proposed, which is populated with existing and innovative unit operations: (i) mineral processing, (ii) metal extraction, (iii) metal recovery and (iv) matrix valorisation. Several promising novel techniques are under development for these four unit-operations. From an economical and environmental point of view, such processes must be fitted into new (circular) business models, whereby impacts and costs are divided over the entire value chain. Currently, low-grade secondary raw material processing is only economic and environmentally beneficial when the mineral residues can be valorised and landfill costs are avoided and/or incentives for waste processing can be taken into account. Presented on

Samarium-153 is a medical radionuclide that serves in nuclear medicine for bone pain palliation or imaging of the skeleton, and is produced in a nuclear research reactor by irradiation of an enriched samarium-152 target with a high flux of thermal neutrons. However, long-lived europium-154 impurities are formed concurrently, which restricts the use of the samarium-153 radiopharmaceutical. Previous research already showed the possibility to separate samarium and europium efficiently by solvent extraction with the undiluted ionic liquid [A336][NO3]. Current research efforts investigated the feasibility to convert the separation method to an extraction chromatography application, taking advantage of solid phase extraction techniques. TEVA particles, where the ionic liquid is immobilized onto a solid support, served as the stationary phase in the column. Eu3+ was reduced to Eu2+ in a concentrated nitrate salt solution prior to the separation step. After loading onto the extraction chromatography column, Eu2+ was not retained by the TEVA particles upon elution with a concentrated nitrate salt solution, whereas Sm3+ was extracted to the ionic liquid layer. Sm3+ could be efficiently removed from the column by elution with water, hence yielding a simple, yet efficient separation method.

Redox flow batteries (RFBs) are currently of interest as energy storage devices with great potential. For non-aqueous RFBs, low-cost redox pairs with good reversibility and high solubility in the organic solvents are exploited to improve battery performance. In this work, two metal complexes, containing cheap and abundant cerium, were proposed with a very good electrochemical reversibility (Ce4+/Ce3+) in acetonitrile. As proof-of-principle, two cerium-based RFBs were designed: a Zn–Ce and a V–Ce RFB. For the Zn–Ce RFB, the Ce4+/Ce3+ and Zn2+/Zn redox pairs yielded an open cell potential of 1.86 V. In a RFB single cell, a coulombic efficiency of 94%, a voltage efficiency of 68% and an energy efficiency of 64% were achieved at 2 mA cm−2. Most importantly, the RFB is non-sensitive to moisture and oxygen, thus significantly decreasing the costs for practical applications. For the V–Ce RFB, a cell potential of 2.34 V was obtained. This high cell potential and the high solubility (more than 2.5 M) of [Ce(Py-O)8][Tf2N]3 in acetonitrile indicates that this type of battery is promising for high-energy density RFB applications. Hence, the cerium-containing complexes are very promising for developing RFB systems with low-cost and high-energy density.

Correction for ‘Split-anion solvent extraction of light rare earths from concentrated chloride aqueous solutions to nitrate organic ionic liquids’ by Mercedes Regadío et al., RSC Adv., 2018, 8, 34754–34763, DOI: 10.1039/c8ra06055j.

An integrated process flow sheet for the recovery of yttrium and europium from waste cathode-ray tube (CRT) phosphors was developed. This flow sheet is based on a sequence of roasting, leaching with organic acids and precipitation steps. Zinc was efficiently removed from the roasted CRT phosphors by leaching with acetic acid, giving access to the rare earth content. Yttrium and europium were quantitatively leached from the residue by a 1 mol L−1 methanesulphonic acid (MSA) solution. Precipitation with oxalic acid gave a mixed Y/Eu oxalate of high purity (>99 wt%). Co-precipitation of zinc was less than 2 wt%. This work has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 680629 (REMAGHIC: New Recovery Processes to produce Rare Earth-Magnesium Alloys of High Performance and Low Cost) (project website: http://www.remaghic-project.eu). The authors acknowledge Relight srl (Rho, Italy) for providing the CRT phosphor powder.

Droplets of aqueous solutions of trivalent lanthanide ions (Ln3+) were formed inside an immiscible fluid. The motion of the droplets, induced by the magnetic field of a Nd-Fe-B permanent magnet, was measured. By using the relationship between the magnetophoretic velocity, the magnetic force, and the frictional coefficient, a good estimate of the magnetic susceptibility was obtained. The impact of the magnetic susceptibility of each Ln3+ ion on the magnetophoresis was analyzed. Additionally, the influence of droplet volume, concentration. and magnetic field strength was also studied. A forward motion toward regions of stronger magnetic field was observed for droplets of paramagnetic solutions, while no motion was detected for droplets of diamagnetic solutions. The average droplet velocity for the different Ln3+ ions across the lanthanide series follows a binodal-shaped curve, which corresponds to the change of the magnetic susceptibility of Ln3+ as a function of the atomic number. Strongly paramagnetic ions develop a considerably higher velocity compared to weakly paramagnetic ions, in a process which we denote here as "magnetophoretic sprinting"., SCOPUS: ar.j, info:eu-repo/semantics/published

The solvent extraction of lanthanides from chloride media to an organic phase containing an anion exchanger in the chloride form is known to show low extraction percentages and small separation factors. The coordination chemistry of the lanthanides in combination with this kind of extractant is poorly understood. Previous work has mainly used solvent extraction based techniques (slope analysis, fittings of the extraction curves) to derive the extraction mechanism of lanthanides from chloride media. In this paper, EXAFS spectra, luminescence lifetimes, excitation and emission spectra, and organic phase loadings of lanthanides in dry, water-saturated and diluted Aliquat 336 chloride or Cyphos IL 101 have been measured. The data show the formation of the hydrated lanthanide ion [Ln(H2O)8–9]3+in undiluted and diluted Aliquat 336 and the complex [LnCl6]3−in dry Aliquat 336. The presence of the same species [Ln(H2O)8–9]3+in the aqueous and in the organic phase explains the small separation factors and the poor selectivities for the separation of mixtures of lanthanides. Changes in separation factors with increasing chloride concentrations can be explained by changes in stability of the lanthanide chloro complexes in the aqueous phase, in combination with the extraction of the hydrated lanthanide ion to the organic phase. Finally, it is shown that the organic phase can be loaded with 107 g·L−1of Nd(III) under the optimal conditions. ispartof: Journal of Solution Chemistry vol:47 issue:8 pages:1351-372 status: published

A process was developed for the recovery of rare earths from terbium-rich lamp phosphor waste. The process consists of a solvometallurgical leaching step with concentrated methanesulphonic acid (MSA) at temperatures between 433 K to 473 K, followed by solvent extraction with the acidic extractant di-(2-ethylhexyl)phosphoric acid (D2EHPA). Preliminary tests were performed on a synthetic lamp phosphor (LaPO

The thermochemical behavior of low-temperature oxidation in fine UO

Cobalt(II)-containing ionic liquids were synthesized using N,N-dimethylformamide, N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), N,N-dimethylacetamide (DMAc), pyridine-N-oxide (py-O), 1,10-phenanthroline (phen), ethylenediamine (en) and dimethylimidazolidinone (DMI) as ligands. The weakly coordinating bis(trifluoromethylsulfonyl)imide (Tf2N−) was used as a counter anion. Several compounds had a melting temperature below 100 °C, and the compound [Co(DMAc)6][Tf2N]2 was liquid at room temperature, with a viscosity of only 18 mPa s at 80 °C. Several compounds were recrystallized to give high quality single crystals and their crystal structures were determined. EXAFS measurements were performed on [Co(DMAc)6][Tf2N]2 at different temperatures and it was observed that the [Co(DMAc)6]2+ ion partially dissociated at higher temperatures, which explains the temperature-dependent color change (thermochromism). The electrochemical properties of the compounds with the lowest melting points were also investigated. Adherent, crack-free metallic cobalt layers could be electrodeposited from [Co(DMAc)6][Tf2N]2, [Co(DMI)6][Tf2N]2 and [Co(NMP)6][Tf2N]2. From the first two, black deposits consisting of micrometer-sized needles were obtained, whereas the latter resulted in a dull grey cobalt layer consisting of micrometer-sized cobalt spheres. The Co(III)/Co(II) redox couple was not found to occur in any compound with an O-donor ligand, but the Co(III)/Co(II) redox couple was found to be quasi-reversible for [Co(phen)3][Tf2N]2 dissolved in [BMP][Tf2N]. ispartof: Dalton Transactions vol:47 issue:14 pages:4975-4986 ispartof: location:England status: published

Ionic liquids (ILs) with trichloride anions ([Cl3]−) combined with different cations were synthesised by bringing chlorine gas into contact with the corresponding chloride (Cl−) ILs at room temperature. These trichloride ILs safely store chlorine and are useful as oxidising agents for dissolution of various metals and alloys under mild conditions. ispartof: Chemical Communications vol:54 issue:5 pages:475-478 ispartof: location:England status: published

© 2017 American Chemical Society. Several ionic liquids (ILs) were tested for their suitability to synthesize the aramid polymer poly-p-phenylene terephthalamide (PPTA) in an attempt to diminish the dependence on the toxic N-methylpyrrolidone (NMP) that is currently used in industry. The room-temperature IL 3-methyl-1-octylimidazolium chloride ([C8MIM][Cl]) showed the highest promise as, with this medium, the polycondensation reaction proceeds with a mechanism similar to how it occurs in the solvent mixture of NMP with CaCl2. With this IL, PPTA polymer with an inherent viscosity of 1.95 dL/g was obtained in a low-temperature polycondensation reaction. This is the highest reported molecular mass of PPTA to date that was obtained by polymerization in an ionic liquid. An extended X-ray absorption fine structure (EXAFS) and solid-state NMR spectroscopic study showed that [C8MIM][Cl] and the current industrial solvent of NMP and CaCl2 show similar characteristics when it comes to the synthesis of PPTA. ispartof: ACS SUSTAINABLE CHEMISTRY & ENGINEERING vol:6 issue:1 pages:1362-1369 status: published

Eight fluorine-functionalized ionic liquids were synthesized and the oxygen solubility was compared to commercial ionic liquids without the extra fluorinated chain. The concentration of dissolved oxygen increased with the fluorine content of the alkyl chain, which can be attached either to the cation or the anion. This approach maintains the freedom to design an ionic liquid for a specific application, while at the same time the oxygen solubility is increased. ispartof: RSC Advances vol:8 issue:9 pages:4525-4530 ispartof: location:England status: published

International audience; Despite its benefits, the extraction of rare earths (REEs) from chloride solutions with neutral or basic extractants is not efficient, so that separation is currently carried out by using acidic extractants. This work aims to improve this process by replacing the conventional molecular diluents in the organic phase by ionic liquids (ILs) which contain coordinating anions. The extraction of La(m), Ce(iii) and Pr(iii) from concentrated chloride solutions was tested with a quaternary ammonium and a phosphonium nitrate IL extractant. Dissolution of a trialkylphosphine oxide neutral extractant (Cyanex 923) in the nitrate ILs changed the preference of the organic phase from lighter to heavier REE and increased the overall extraction efficiency and the loading capacity of the organic phase. An increase of the CaCl2 concentration in the feed solution resulted in higher extraction efficiencies, due to a lower activity of water and hence to a poorer hydration of the REE ions. In that respect, chloride ions were not coordinating to the REE ion after extraction from concentrated chloride solutions. To achieve selectivity, one should fine-tune the loading by varying the CaCl2 and/or Cyanex 923 concentrations. Adjustment of the CaCl2 concentration in the feed and stripping solutions is essential for the separation of mixtures of REE. However, and unlike in the case of acidic extractants, no control of equilibrium pH is required. The split-anion extraction offers the possibility to separate mixtures of REEs in different groups without having to change the chloride feed solution. It leads to safer and environmentally friendlier extraction processes by (1) using solvents that are not volatile, not flammable and do no accumulate static electricity, (2) consuming no acids or alkali, (3) easy stripping with water and (4) avoidance to create nitrate-containing effluents.

Bauxite residue (BR) contains substantial concentrations of rare-earth elements (REEs), but their recovery is a challenge. Acidic BR leachates typically comprise much higher concentrations of base elements (g L−1) than those of the REEs (ppm). Thus, adsorbents that are highly selective for the REEs over the base elements are required for the separation. The novel supported ionic liquid phase (SILP) betainium sulfonyl(trifluoromethanesulfonylimide) poly(styrene-co-divinylbenzene) [Hbet-STFSI-PS-DVB] was evaluated for the uptake of REEs (Sc, Y, Nd, Dy) in the presence of base elements (Ca, Al, Fe) from BR leachates. Breakthrough curves from acidic nitrate and sulfate media were investigated, as both HNO3 and H2SO4 are commonly used for leaching of BR. The SILP exhibited a superior affinity for REEs in both media, except in the case of Sc(III) from the sulfate feed. The recovery rates of the trace amounts of REEs from the real nitrate feed were remarkably high (71.7–100%) via a simple chromatography separation, without requiring complexing agents or a pretreatment for the removal of interfering elements. The REEs were purified from the base elements and separated into three sub-groups (scandium, light REEs and heavy REEs) by an optimized elution profile with H3PO4 and HNO3 in a single chromatographic separation step. ispartof: RSC Advances vol:8 issue:22 pages:11886-11893 ispartof: location:England status: published

Lanthanides are extracted to basic nitrate-based extractants, like trihexyl(tetradecyl)phosphonium nitrate, as pentanitrato lanthanide complexes., A speciation study was carried out for lanthanide complexes formed in the organic phase after solvent extraction with quaternary ammonium and phosphonium nitrate extractants. These extractants are liquid at room temperature and were applied in their undiluted form. A comparison was made between the quaternary compound trihexyl(tetradecyl)phosphonium nitrate, the nitrate form of the commercial extractant Cyphos IL 101, and Aliquat 336 nitrate, the nitrate form of the commercial trialkylmethylammonium chloride extractant Aliquat 336 (alkyl = mixture of C8 and C10 chains). The structures of the lanthanide complexes across the entire lanthanide series (with the exception of promethium) were determined by a combination of solvent extraction techniques, FTIR, NMR, high-resolution steady-state luminescence spectroscopy, luminescence life time measurements, elemental analysis and EXAFS spectroscopy. The results suggest that the lanthanide ions form an anionic nitrate complex in the organic phase by coordinating with five bidentate nitrate ligands. Charge neutralization is provided by two counter cations of the extractant present in the outer coordination sphere of the complex. Furthermore, it is suggested that the pentanitrato complex is the sole lanthanide species that is formed in significant concentrations in the organic phase.

The balance between the market demand and the natural abundance of the rare-earth elements (REEs) in ores, often referred to as the Balance Problem (or the Balancing Problem), is a major issue for REE suppliers. The ideal situation is a perfect match between the market demand for and the production of REEs, so that there are no surpluses of any of the REEs. This means that the rare-earth industry must find new uses for REEs that are available in excess and search for substitutes for REEs that have either limited availability or are high in demand. We present an overview of the trends in the applications for the different REEs and show that the demand for REEs for use in magnets, catalysts, and alloys is still increasing, while the application of REEs in polishing agents, glass, and ceramics are stable. On the other hand, the use of REEs in nickel–metal-hydride (NiMH) batteries and lamp phosphors is decreasing. These changes in the REE market have an influence on the Balance Problem, because the REEs that can be recycled from fluorescent lamps, cathode-ray tubes (CRTs), and NiMH batteries have to be at least partly reused in other applications. Magnesium and aluminum alloys offer an opportunity to mitigate the Balance Problem caused by these changes in the REE market. This is illustrated for REEs that can be recycled from fluorescent-lamp phosphor waste, CRT phosphors, and NiMH batteries. At present, five REEs (Nd, Eu, Tb, Dy, and Y) are being considered as very critical by Europe, the United States, and Japan, but we forecast that in the medium term, only neodymium will remain a critical REE. This paper discusses the relationship between criticality and the Balance Problem and shows how this relationship influences the market for specific REEs. This work has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 680629 (REMAGHIC: New Recovery Processes to produce Rare Earth-Magnesium Alloys of High Performance and Low Cost) (project website: http://www.remaghic-project. eu). KB and PTJ acknowledge funding from the European Community’s Seventh Framework Programme ([FP7/2007–2013]) under Grant Agreement No. 607411 (MC-ITN EREAN: European Rare Earth Magnet Recycling Network) (project website of EREAN: http:// www.erean.eu). Paul McGuiness (Sciencewriter.si, Slovenia) is acknowledged for the drawing of the figures.

In this work, the extraction of selected rare earth elements from bauxite residue by dry digestion method followed by water leaching was investigated. Kinetic studies performed with HCl and H2SO4 demonstrated that, at ambient temperatures, silica dissolution increases with increasing acid concentration, which leads to the formation of silica gel. Dissolution of silica is limited to less than 5 wt% by applying a two-step process: dry digestion of bauxite residue with HCl or H2SO4, followed by water leaching. The extraction of aluminium was low because of the low solubility of aluminosilicate compounds. The extraction of iron and titanium increased with increasing acid concentrations. High extraction of the rare-earth elements (REEs) were achieved with the HCl-based dry digestion method, but the concentration in the leachate was limited to approximately 6–8 mg L−1. About 40 wt% of scandium was recovered with a high co-dissolution of iron, due to the occurrence of scandium(III) ions in the lattice matrix of iron(III) oxide. Dry digestion method with multi-stage circulation of the acid leaching solution significantly increased the REEs concentration up to 20 mg L−1, while achieving an acid consumption of 788 g of HCl per kilogram of bauxite residue, and a significant reduction of water consumption (60%) relative to the single-stage acidic leaching method. The low water consumption allows to increase the filtration efficiency of the leach liquor due to the avoidance of silica gel formation.

Solvent extraction is a widely used separation technique in extractive metallurgy. A conventional solvent extraction system consists of an aqueous phase and an immiscible organic phase. In this work, we show that replacement of water by a polar organic solvent can lead to superior metal separations. Cobalt(II) and samarium(III) chlorides dissolved in water and ethylene glycol (EG), respectively, with LiCl as chloride source, were extracted by Aliquat 336 diluted in toluene. Both cobalt and samarium were extracted from the aqueous solutions, but cobalt was extracted more efficiently from the ethylene glycol solutions than from the aqueous solutions, whereas samarium was not extracted at all from the ethylene glycol solutions. As a result, cobalt and samarium could be separated completely in a single extraction step from ethylene glycol solutions. The mechanisms of cobalt extraction by Aliquat 336 from the ethylene glycol and aqueous solutions were found to be similar, as validated by slope analysis and UV-VIS absorption spectroscopy. Samarium was extracted from the aqueous solution through the salting-out effect of LiCl. Interestingly, LiCl has a much lower salting-out effect for samarium in ethylene glycol than in water due to the lower dielectric constant of ethylene glycol and the lower solubility of LiCl in ethylene glycol. Consequently, samarium is not salted out from ethylene glycol, leading to a very efficient separation of cobalt and samarium. This separation effect can also be applied to the separation of other transition metal and rare-earth metal pairs, including iron/neodymium and zinc/europium. ispartof: Separation and Purification Technology vol:201 pages:318-326 status: published

During acid leaching of bauxite residue (red mud), the increase in dissolution of rare-earth elements (REEs) is associated with an increase in iron dissolution, which poses problems in the downstream processing. Therefore, it would be beneficial to remove iron from bauxite residue by smelting reduction. The slag generated in the smelting reduction process could then be further processed for recovery of REEs. Smelting experiments were carried out at temperatures between 1500 and 1600 °C. Wollastonite (CaSiO3) was used as a flux and graphite as a reducing agent. The addition of wollastonite decreases the slag melting temperature and the viscosity, facilitating slag-metal separation, whereas a graphite content higher than the optimum level alters the slag chemistry and hinders the slag-metal separation. The optimum conditions were found to be for heating at 1500 °C: 20 wt% of wollastonite and 5 wt% of graphite. More than 85 wt% of the iron was separated from the slag in the form of a nugget. A further 10 wt% of the iron could be extracted from the slag by subsequent grinding and magnetic separation. The slag obtained after iron removal was treated with HCl, HNO3, and H2SO4 acids to extract REEs. Room-temperature leaching was found to be not beneficial for REEs extraction. High-temperature leaching enhanced the recovery of REEs. More than 95 % of scandium, >70 % of REEs, and about 70 % of titanium could be leached at 90 °C. The selectivity of REEs over iron during slag leaching was clearly improved.

In a conventional solvent extraction system, metal ions are distributed between two immiscible phases, typically an aqueous and an organic phase. In this paper, the proof-of-principle is given for the distribution of metal ions between three immiscible phases, two ionic liquid phases with an aqueous phase in between them. Three-liquid-phase solvent extraction allows separation of a mixture of three metal ions in a single step, whereas at least two steps are required to separate three metals in the case of two-liquid phase solvent extraction. In the triphasic system, the lower organic phase is comprised of the ionic liquid betainium- or choline bis(trifluoromethylsulfonyl)imide, whereas the upper organic phase is comprised of the ionic liquid trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide. The triphasic system was used for the separation of a mixture of tin(II), yttrium(III), and scandium(III) ions. ispartof: Chemistry - a European Journal vol:21 issue:33 pages:11757-11766 ispartof: location:Germany status: published

The trivalent europium ion (Eu3+) is well known for its strong luminescence in the red spectral region, but this ion is also interesting from a theoretical point of view. Due to the even number of electrons in the 4f shell 4f6 configuration), the crystal-field perturbation by the crystalline host matrix lifts partly or completely the degeneracies of the 2S+1LJ levels. The Eu3+ ion has the great advantage over other lanthanide ions with an even number of 4f electrons that the starting levels of the transitions in both the absorption and the luminescence spectrum are non-degenerate (J = 0). Moreover, the interpretation of the spectra is facilitated by the small total angular momentum J of the end levels in the transitions.The number of lines observed for the 5D0→7FJ transitions in the luminescence spectrum or the 5DJ←7F0 transitions in the absorption spectrum allows determining the site symmetry of the Eu3+ ion. This review describes the spectroscopic properties of the trivalent europium ion, with emphasis on the energy level structure, the intensities of the f–f transitions (including the Judd–Ofelt theory), the decay times of the excited states and the use of the Eu3+ion as a spectroscopic probe for site symmetry determination. It is illustrated how the maximum amount of information can be extracted from optical absorption and luminescence spectra of europium(III) compounds, and how pitfalls in the interpretation of these spectra can be avoided. ispartof: Coordination Chemistry Reviews vol:295 pages:1-45 status: published

Uranium dioxide (urania, UO2) and thorium dioxide (thoria, ThO2) doped with gadolinium oxide (gadolinia, Gd2O3) were prepared via solid-state synthesis. For Gd2O3-doped ThO2, also an alternative, semi-dry process (“suspension coating”) was applied in which Gd2O3-coated ThO2 powder was produced via suspension drying followed by calcination. The microstructure and homogeneity of the materials were investigated by ceramography, EPMA and XRD. Solid-state synthesis is a convenient method to produce Gd2O3-doped UO2. However, this route was found to be inappropriate to obtain Gd2O3-doped ThO2 with an acceptable microstructure and homogeneity. The suspension coating process reported in this work is a simple and practical method to overcome these issues.

Nickel–zinc alloys were electrodeposited on copper gauze from an acetamide–dimethyl sulfone eutectic mixture containing nickel chloride and zinc chloride. The as-deposited nickel–zinc alloys have compact microstructures with very small crystallites (approximately 3 nm) and smooth surfaces. The nickel content could be varied between 20 and 90 wt.% by controlling the temperature of the electrolyte. After alkaline leaching, a gauze-supported zinc based Raney nickel catalyst was obtained. The catalyst was benchmarked against commercial aluminum based Raney nickel in liquid phase hydrogenation of acetophenone. The gauze-supported zinc based skeletal nickel was more active and selective as compared to the commercial aluminum based Raney nickel. In addition, the gauze-supported zinc based Raney nickel catalyst could be reused without any hydrogen pretreatment. The activity of the reused catalyst decreased by 20%, but it retained its excellent selectivity.

Bauxite residue (or red mud) is a waste generated during the Bayer process of alumina production. Its storage is a spatial and environmental concern. Currently, there are no bulk applications of bauxite residue except for minor use in cements and ceramics. Nonetheless, some types of bauxite residues are rich in rare-earth elements (REEs), and the extraction of scandium in particular is of special interest. Leaching experiments on Greek bauxite residue were performed with different acids at different concentrations, liquid-to-solid ratios, leaching times and temperatures. Extraction of the REEs was high for leaching in HCl solutions compared to other acids, but the dissolution of iron was high as well (60%). The maximum extraction of the REEs was around 80%. Sodium and calcium were completely dissolved during leaching. Dissolution of aluminum, silicon and titanium was between 30% and 50%. The leaching data show a very close association of scandium with the iron oxide phases. ispartof: Minerals Engineering vol:76 pages:20-27 status: published

A flow sheet has been developed for recovery of metals from nickel metal hydride batteries using the neutral extractant Cyanex 923 dissolved in the ionic liquid tricaprylylmethylammonium nitrate, (A336)(NO3), and a synthetic chloride-based aqueous leach solution. The pro- cess allows purification of nickel in a single step by ex- tracting chloride and nitrate complexes of the extractable transition metals and rare earths. Three selective strip op- erations utilizing first nitrate, stripping cobalt and man- ganese, and then chloride complexation, stripping the rare earths, followed by stripping of iron and zinc. Cobalt in the nitrate strip solution was separated from manganese by extraction with the ionic liquid tricaprylylmethylammoni- um thiocyanate, (A336)(SCN).

The photochemistry of a gold(I) thiocyanate complex has been investigated to determine the coordination structure in both the solid and liquid states. The coordination geometries of the supramolecular [Au(SCN)2]n complex and the concomitant exciplex have mainly been analyzed by crystallographic analysis and X-ray absorption spectroscopy. The Au–S bond distance and Au···Au separation of the compound in the S0 ground state and in the T1 phosphorescent excited state (λex = 340 nm) were compared. Upon irradiation with UV light, the excimeric interactions were enhanced, resulting in a contraction of the AuI···AuI aurophilic distance by 0.0113(4) A. A broad luminescence spectrum was observed for the one-dimensional chain suprastructure. The time-resolved luminescence spectra indicated the entity of several oligomeric species in the crude liquid without neutral solvent molecules. In addition, extended X-ray absorption fine structure spectroscopy exhibited a slight change in the nearest Au–S distance due to the p...

The ionic liquid betainium is(trifluoromethylsulfonyl)imide [Hbet][Tf2N] was used for the extraction of scandium from aqueous solutions. The influence of several extraction parameters on the extraction efficiency was investigated, including the initial metal concentration, phase ratio, and pH. The extraction kinetics was examined, and a comparison was made between conventional liquid−liquid extraction and homogeneous liquid−liquid extraction (HLLE). The stoichiometry of the extracted scandium complex was determined with slope analysis. Scandium(III) is extracted as a complex with zwitterionic betaine in a 1:3 stoichiometry, with three bis(trifluoromethylsulfonyl)imide counterions. Upon extraction of scandium(III), proton exchange occurs and three protons are transferred to the aqueous phase. Scandium is an important minor element present in bauxite residue (red mud), the waste product that results from the industrial production of alumina by the Bayer process. To evaluate the suitability of [Hbet][Tf2N] for the selective recovery of scandium(III) from red mud leachates, the extraction of other metals present in the leachates (La(III), Ce(III), Nd(III), Dy(III), Y(III), Fe(III), Al(III), Ti(IV), Ca(II), Na(I)) was considered. It was shown that the trivalent lanthanide ions, yttrium(III) and the major elements aluminum(III), titanium(IV), calcium(II), and sodium(I), are all poorly extracted, which is advantageous for the selective recovery of scandium(III) from red mud. Iron(III) showed an extraction behavior similar to that of scandium(III). Scandium recovery was examined from a multielement rare-earth solution. Scandium could be separated from the other rare-earth elements by extraction with [Hbet][Tf2N] and subsequent scrubbing of the loaded ionic liquid phase to remove coextracted metal ions. The extracted scandium was recovered from the ionic liquid phase by using back-extraction with hydrochloric acid or precipitation stripping with oxalic acid. ispartof: Industrial & Engineering Chemistry Research vol:54 issue:6 pages:1887-1898 status: published

Temperature-dependent switching of paramagnetism of a cobalt(II) complex is observed in an ionic liquid solution. Paramagnetic and thermochromic switching occur simultaneously due to a reversible change in coordination. This reversible switching is possible in the ionic liquid solution, which enables mobility of thiocyanate anions by remaining mobile at low temperatures and acts as an anion reservoir. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Solveig Felton (ResearcherID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0) history: Received 15 May 2015; Accepted 2 June 2015; Accepted Manuscript published 2 June 2015; Advance Article published 8 June 2015; Version of Record published 17 June 2015 ispartof: Dalton Transactions vol:44 issue:25 pages:11286-11289 ispartof: location:England status: published