Recovery of Rare Earth Elements (REEs) Using Ionic Solvents

Rare earth elements (REEs) are becoming more and more significant as they play crucial roles in many advanced technologies. Therefore, the development of optimized processes for their recovery, whether from primary resources or from secondary sources, has become necessary, including recovery from mine tailings, recycling of end-of-life products and urban and industrial waste. Ionic solvents, including ionic liquids (ILs) and deep-eutectic solvents (DESs), have attracted much attention since they represent an alternative to conventional processes for metal recovery. These systems are used as reactive agents in leaching and extraction processes. The most significant studies reported in the last decade regarding the recovery of REEs are presented in this review

Auto-assemblage d'organosilices par reconnaissance moléculaire

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Selective Extraction of REEs Thanks to One-Pot Silica Hybrid Materials

International audienceThe importance of rare-earth elements (REEs) in the global economy is rapidly growing, since they are essential to many advanced technologies. Therefore, the development of more performant separation procedures for REEs has become necessary. In the present study, we used silica hybrid materials (SHMs), which were synthesized by an all-in-one approach that allows the direct incorporation of desired functional groups, as sorbent material. Promising results were obtained for the extraction capacities of diglycolamide-functionalized materials. Under the tested conditions, they showed high efficiency (Nd uptake capacity of about 25 mg per g of material) and high selectivity toward REEs from a simulated NdFeB magnet leachate. For these materials, Nd recovery after extraction was achieved with an efficiency of 80% by contacting the loaded material with distilled water at moderate pH (6.5)

Tailored structuring of functionalized silsesquioxanes in a one-step approach

International audienceThe silica hybrid materials prepared from tailor-made precursors with different headgroups in several experimental conditions (acid or base catalysis in water or THF) were studied in order to identify the structure directing mechanisms

Efficient and multi-function compatible click-reaction of organosilanes

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From colloidal precursors to metal carbides nanocomposites MC (M=Ti, Zr, Hf and Si): Synthesis, characterization and optical spectral selectivity studies

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Tantalum and Niobium Selective Extraction by Alkyl-Acetophenone

A study has been carried out on Ta and Nb recovery by a liquid-liquid extraction process using 4-methylacetophenone (4-MAcPh) as the organic phase. The 4-MAcPh was compared to methyl isobutyl ketone (MIBK) with respect to extraction efficiencies (D values) at different concentrations of H2SO4 in the aqueous phase. The results showed a similar extraction of Nb for both solvents. However, for Ta, extraction efficiency is increased by a factor of 1.3 for 4-MAcPh. In addition, the MIBK solubilized completely after 6 mol∙L−1 of H2SO4 against only a loss of 0.14–4% for 4-MAcPh between 6 and 9 mol∙L−1 of H2SO4. The potential of 4-MAcPh has also been studied to selectively recover Ta from a model capacitor waste solution. The results showed a selectivity for Ta in the presence of impurities such as Ag, Fe, Ni and Mn. The 4-MAcPh also presents the advantage of having physicochemical properties adapted to its use in liquid-liquid extraction technologies such as mixer-settlers

Impact of Solvent Structuring in Water/ tert -Butanol Mixtures on the Assembly of Silica Nanoparticles to Aerogels

International audienceSoft matter structuring is a useful tool for the preparation of well-structured inorganic materials. Here, we report a strategy using a structured solvent based on binary mixtures as a directing agent for silica nanoparticles in aerogel elaboration. Binary mixtures involving water/ethanol and water/tert-butanol have been respectively chosen as representatives of unstructured and structured solvents. The water/alcohol/TEOS systems were effectively characterized as surfactant-free microemulsions. The enhanced solvent structuring, however, disappears upon the reaction with TEOS, and assembly is directed by solvent structuring found in the binary mixtures. For the first time, the influence of solvent composition on the sol–gel reaction was investigated with respect to the reaction rate and the structuring behavior thanks to dynamic light scattering (DLS), small- and wide-angle X-ray scattering (SWAXS), and transmission electron microscopy (TEM) experiments. The silica nanoparticles aggregate in a different manner depending on the solvent composition, which allows the change in the morphology, the degree of interconnection, and the surface area of the resulting material. Silica nanoparticles with a very high surface area of up to 2000 m2/g can be obtained by this approach

Leaching of rare earth elements (REEs) and impurities from phosphogypsum: A preliminary insight for further recovery of critical raw materials

International audiencePhosphogypsum is a pollutant waste generated by the fertilizer industry. Managing this pollutant is challenging due to the large volumes generated worldwide. A promising route is the valorization of phosphogypsum to recover rare earth elements. However, optimized recovery schemes are needed to create a cost-effective and environmentally friendly process. This paper studies the extraction efficiency of rare earth elements from phosphogypsum and the release of impurities during leaching in a variety of solutions and different working conditions. The best leaching performance was obtained using a 3 M nitric acid (above 80%) solution that achieved a dissolution rate of 63% of the gypsum originally present. In contrast, using 0.5 M sulfuric acid extracted between 46% and 58% of the rare earth elements contained in phosphogypsum, dissolving less than 6% of the gypsum. This higher dissolution of gypsum led to a higher release of impurities by nitric acid. Increasing reaction times from 2 h to 8 h yielded an improvement of leaching efficiency of around 8% for both leaching solutions, while also promoting an increase of 6% in the release of impurities. Adding DTPA resulted in poor leaching performance (from 13% to 22%). Pretreating phosphogypsum with water can remove a significant fraction of the impurities without scavenging rare earth elements. Mineralogical and chemical evidence suggests unreacted phosphate and fluoride are the most probable minerals hosting rare earth element minerals in phos-phogypsum. The results of this study could contribute to optimizing recovery methods to extract rare earth elements from phosphogypsum worldwide, thus helping achieve the goals of the circular economy