Tuneable separation of gold by selective precipitation using a simple and recyclable diamide

The separation of metals from electronic waste is an enduring technological and societal challenge, and new metal extraction, refining and recycling solutions are needed. Here the authors report a recyclable and tuneable chemical reagent that separates valuable metals such as gold by direct and selective precipitation from various acidic, mixed-metal solutions of relevance to extraction and recycling industries

Reducing the Competition: A Dual-Purpose Ionic Liquid for the Extraction of Gallium from Iron Chloride Solutions

The separation of gallium from iron by solvent extraction from chloride media is challenging because the anionic chloridometalates, FeCl4− and GaCl4−, display similar chemical properties. However, we report here that the selective separation of gallium from iron in HCl solution can be achieved using the dual-purpose ionic liquid methyltrioctylammonium iodide in a solvent extraction process. In this case, the reduction of Fe3+ to Fe2+ by the iodide counterion was found to inhibit Fe transport, facilitating quantitative Ga extraction by the ionic liquid with minimal Fe extraction from 2 M HCl

Understanding the recovery of rare-earth elements by ammonium salts

While the recovery of rare earth elements (REEs) from aqueous solution by ionic liquids (ILs) has been well documented, the metal compounds that are formed in the organic phase remain poorly characterized. Using spectroscopic, analytical, and computational techniques, we provide detailed chemical analysis of the compounds formed in the organic phase during the solvent extraction of REEs by [(n-octyl)3NMe][NO3] (IL). These experiments show that REE recovery using IL is a rapid process and that IL is highly durable. Karl-Fischer measurements signify that the mode of action is unlikely to be micellar, while ions of the general formula REE(NO3)4(IL)2− are seen by negative ion electrospray ionization mass spectrometry. Additionally, variable temperature 139La nuclear magnetic resonance spectroscopy suggests the presence of multiple, low symmetry nitrato species. Classical molecular dynamics simulations show aggregation of multiple ILs around a microhydrated La3+ cation with four nitrates completing the inner coordination sphere. This increased understanding is now being exploited to develop stronger and more selective, functionalized ILs for REE recovery

Shape-Selective Supramolecular Capsules for Actinide Precipitation and Separation

Improving actinide separations is key to reducing barriers to medical and industrial actinide isotope production and to addressing the challenges associated with the reprocessing of spent nuclear fuel. Here, we report the first example of a supramolecular anion recognition process that can achieve this goal. We have designed a preorganized triamidoarene receptor that induces quantitative precipitation of the early actinides Th(IV), Np(IV), and Pu(IV) from industrially relevant conditions through the formation of self-assembled hydrogen-bonded capsules. Selectivity over the later An(III) elements is shown through modulation of the nitric acid concentration, and no precipitation of actinyl or transition-metal ions occurs. The Np, Pu, and Am precipitates were characterized structurally by single-crystal X-ray diffraction and reveal shape specificity of the internal hydrogen-bonding array for the encapsulated hexanitratometalates. This work complements ion-exchange resins for 5f-element separations and illustrates the significant potential of supramolecular separation methods that target anionic actinide species

A Simple Supramolecular Approach to Recycling Rare Earth Elements

The rapid increase in demand for rare-earth elements reflects their crucial roles in climate critical technologies. However, the lack of simple solutions for the separation of these metals from waste materials and ores represents a significant barrier to sustainable and environmentally benign rare-earth production. We report the application of a supramolecular approach to this challenge, using a triamido-arene receptor to selectively precipitate f-elements through their encapsulation as hexanitratometalates. Single-step, near quantitative recovery of Nd/Pr directly from magnet scrap was observed without the need for pH adjustment or pretreatment of the acidic leach solution. The rare-earth nitrate was rapidly stripped from the host−guest precipitate with water and the receptor recycled for further use. Near quantitative and highly selective uptake of La−Nd and Th from lateritic rare-earth ores was also achieved with no uptake of any non-f-element. These results show that targeting f-element metalates in separations chemistry can deliver exceptional and unique selectivity that may have significant consequences in the sustainable production of the rare-earth elements

Does the impact of osteoarthritis vary by age, gender and social deprivation? A community study using the International Classification of Functioning, Disability and Health

The aim of the study was to explore if the impact of osteoarthritis varies with respect to age, gender and social deprivation. Impact was defined as impairment, activity limitations and participation restriction (International Classification of Functioning, Disability and Health (ICF)). Investigating the functioning of the ICF model for subgroups is important both practically and theoretically.  The sample comprised a community sample of 763 people diagnosed with osteoarthritis. Uncontaminated measures of the ICF constructs were developed using discriminant content validity from a pool of 134 items, including the WOMAC and SF-36. Multigroup Structural Equation Modelling was used to explore if the same pathways exist for subgroups of gender, age and social deprivation. Results: Different significant paths were found for gender and social deprivation: impairment did not predict participation restriction for women and those most deprived, whereas these paths were significant for men and those less deprived. No difference in the paths was found for age. The impact of osteoarthritis appears to vary with respect to gender and social deprivation but not age. This suggests both that osteoarthritis per se does not adequately explain the health outcomes observed and that different clinical approaches may be appropriate for people of different gender and levels of deprivation. Implications of Rehabilitation • The ICF model appears to vary with respect to gender and social deprivation for people with osteoarthritis. • The ICF model did not appear to vary with respect to age for people with osteoarthritis. • Different treatments and interventions for osteoarthritis may need to be targeted for specific gender and social deprivation groups

Human gene therapy for RPE65 isomerase deficiency activates the retinoid cycle of vision but with slow rod kinetics

The RPE65 gene encodes the isomerase of the retinoid cycle, the enzymatic pathway that underlies mammalian vision. Mutations in RPE65 disrupt the retinoid cycle and cause a congenital human blindness known as Leber congenital amaurosis (LCA). We used adeno-associated virus-2-based RPE65 gene replacement therapy to treat three young adults with RPE65-LCA and measured their vision before and up to 90 days after the intervention. All three patients showed a statistically significant increase in visual sensitivity at 30 days after treatment localized to retinal areas that had received the vector. There were no changes in the effect between 30 and 90 days. Both cone- and rod-photoreceptor-based vision could be demonstrated in treated areas. For cones, there were increases of up to 1.7 log units (i.e., 50 fold); and for rods, there were gains of up to 4.8 log units (i.e., 63,000 fold). To assess what fraction of full vision potential was restored by gene therapy, we related the degree of light sensitivity to the level of remaining photoreceptors within the treatment area. We found that the intervention could overcome nearly all of the loss of light sensitivity resulting from the biochemical blockade. However, this reconstituted retinoid cycle was not completely normal. Resensitization kinetics of the newly treated rods were remarkably slow and required 8 h or more for the attainment of full sensitivity, compared with \u3c1 h in normal eyes. Cone-sensitivity recovery time was rapid. These results demonstrate\u3edramatic, albeit imperfect, recovery of rod- and cone-photoreceptor-based vision after RPE65 gene therapy

Modelling of Short-Term Interactions Between Concrete Support and the Excavated Damage Zone Around Galleries Drilled in Callovo–Oxfordian Claystone

peer reviewedProduction of energy from nuclear power plants generates high-level radioactive nuclear waste, harmful during dozens of thousand years. Deep geological disposal of nuclear waste represents the most reliable solutions for its safe isolation. Confinement of radioactive wastes relies on the multi-barrier concept in which isolation is provided by a series of engineered (canister, backfill) and natural (host rock) barriers. Few underground research laboratories have been built all over the world to test and validate storage solutions. The underground drilling process of disposal drifts may generate cracks, fractures/strain localisation in shear bands within the rock surrounding the gallery especially in argillaceous rocks. These degradations affect the hydro-mechanical properties of the material, such as permeability, e.g. creating a preferential flow path for radionuclide migration. Hydraulic conductivity increase within this zone must remain limited to preserve the natural barrier. In addition galleries are currently reinforced by different types of concrete supports such as shotcrete and/or prefab elements. Their purpose is twofold: avoiding partial collapse of the tunnel during drilling operations and limiting convergence of the surrounding rock. Properties of both concrete and rock mass are time dependent, due to shotcrete hydration and hydromechanical couplings within the host rock. By the use of a hydro-mechanical coupled Finite Element Code with a Second Gradient regularization, this paper aims at investigating and predicting support and rock interactions (convergence, stress field). The effect of shotcrete hydration evolution, spraying time and use of compressible wedges is studied in order to determine their relative influence