Rare-earth elements (REEs) are critical to the production of modern integrated electronic devices that are ubiquitous in our lives. They are also of strategic importance to our economy and security. Unfortunately, although electronic waste contains such elements, its overall low concentration makes its recovery economically impractical, posing a significant challenge to recycling efforts. Hence, this paper proposes changes to the extraction process that focus on the potential for economically viable recovery. In addition, it also reduces the environmental impact of downstream hydrometallurgical processes. More precisely, this study presents novel extraction molecules that exhibit exceptional solubility and extraction efficiencies in supercritical carbon dioxide. This development therefore provides an alternative process to traditional hydrometallurgical processes that is more environmentally friendly and addresses the urgent need for sustainable methods of REE recovery and separation.

Aqueous foams have been used in various hydrometallurgical processes, and have recently emerged as an alternative technique for the leaching of metallic copper, using hydrochloric acid and O2 from air as an oxidant. In the present study, we describe how this technique has been successfully applied to the leaching of copper from waste printed circuits boards (WPCBs). First of all, the use of HCl based foams was successfully applied to the leaching of sole copper, and the impact of the size of copper particles was studied. It was demonstrated that use of mixtures of fine and large particles give excellent results. Then, on ground WPCBs, a first classical leaching stage using aqueous HCl solution was performed in order to remove maximum quantity of reducible metals (aluminum, iron, zinc ...). Then, almost quantitative copper leaching employing HCl based foam was performed. Copper is almost exclusively leached during this stage, and the complete mass balance in 5 major metals present in WPCBs (aluminum, iron, zinc, nickel and copper) is detailed. Kinetics of the copper leaching were greatly enhanced through addition of substoechiometric quantity of cupric ions at the beginning of the process, so that extensive grinding of the waste is not necessary.

AbstractDirect recycling is a novel approach to overcoming the drawbacks of conventional lithium‐ion battery (LIB) recycling processes and has gained considerable attention from the academic and industrial sectors in recent years. The primary objective of directly recycling LIBs is to efficiently recover and restore the active electrode materials and other components in the solid phase while retaining electrochemical performance. This technology's advantages over traditional pyrometallurgy and hydrometallurgy are cost‐effectiveness, energy efficiency, and sustainability, and it preserves the material structure and morphology and can shorten the overall recycling path. This review extensively discusses the advancements in the direct recycling of LIBs, including battery sorting, pretreatment processes, separation of cathode and anode materials, and regeneration and quality enhancement of electrode materials. It encompasses various approaches to successfully regenerate high‐value electrode materials and streamlining the recovery process without compromising their electrochemical properties. Furthermore, we highlight key challenges in direct recycling when scaled from lab to industries in four perspectives: (1) battery design, (2) disassembling, (3) electrode delamination, and (4) commercialization and sustainability. Based on these challenges and changing market trends, a few strategies are discussed to aid direct recycling efforts, such as binders, electrolyte selection, and alternative battery designs; and recent transitions and technological advancements in the battery industry are presented.

Recycling waste nuclear fuel through the production of mixed oxide (MOx) fuel allows for sustainable management of natural nuclear resources. With the aim of reducing the number of steps required for recycling U and Pu, the possibility of precipitating them directly from the organic phase (also referred to as precipitation stripping) using oxalic acid, is investigated herein. For practical reasons, proof-of-concept studies were performed using U(VI) and Th(IV), with the latter serving as a first model for Pu(IV). The results obtained show that, by controlling the concentrations of oxalic and nitric acids in the precipitation medium, total precipitation of Th and partial precipitation of U from the organic phase are attained. The actinides are precipitated in the form of oxalates, with the complete absence of impurities. Furthermore, the precipitates obtained can then be totally separated through washing with water, as proven by X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analyses. This allows control over the U:Th mass ratio in the final product. This work demonstrates the effectiveness of precipitation stripping using oxalic acid for the stripping of Th and U present in the organic phase, eliminating the need for reducing agents classically employed in the PUREX process.

Supramolecular organization of amphiphilic extractant molecules is involved in metal cation selectivity and separation kinetics during solvent extraction. The relationship between extractant associates/aggregates formed in the organic bulk phase and at the liquid–liquid interface is poorly understood even though it affects the extraction mechanism. The nanoscopic structures of the extraction systems N,N,N′,N′-tetrahexylmalonamide (THMA) in toluene and N,N′-dibutyl-N,N′-dimethyl-2-tetradecylmalonamide (DBMA) in n-heptane, used for either Pd(II) or Nd(III) selective extraction from an acidic aqueous phase, were examined. These systems present markedly different affinity for Pd(II) and Nd(III), and extraction kinetics. Extractant organization in the organic bulk phase and at the interface were compared by small-angle X-ray scattering, interfacial tension, and neutron reflectivity. THMA in toluene forms small associates in the organic bulk phase and accumulates in a diffuse layer at the interface, decreasing Pd(II) coordination probability and resulting in slow extraction. DBMA in n-heptane forms large aggregates and a compact, dense interfacial layer, resulting in rapid Pd(II) and Nd(III) extraction. Thus, Pd(II) extraction is driven by interfacial coordination alone, whereas the incorporation of Nd(III) into the core of large aggregates governs Nd(III) extraction in the interfacial layer. These results suggest that the interface should be described as a nanoscale interphase containing a high extractant concentration compared with the organic bulk phase.

In this work, we develop a two-stepprocess for the controlledgrowth of a thin layer of a functionalized and photosensitive metal-organicframework (MOF), namely Ru-Ti-UiO-67, on the surfaceof a plate coated with indium tin oxide (ITO), a transparent conductiveoxide (TCO). In the first step, the in situ controlledgrowth of a layer of UiO-67-based MOF doped with a photosensitizer(ruthenium complex), herein referred to as Ru-UiO-67, is carriedout on the surface of the ITO-coated plate, leading to Ru-UiO-67/ITO.The obtained MOF layer is relatively thin, allowing increased interactionsbetween the MOF material and the TCO surface, and consists of crystalsin the near-nanometer particle size. In the second step, a postsyntheticmodification (PSM) process is applied to Ru-UiO-67/ITO to integrateTi catalytic sites into the MOF framework, leading to Ru-Ti-UiO-67/ITO(containing both the photosensitizer and catalyst) while maintainingthe MOF's structure and morphology in addition to its stronginteraction with the substrate. Importantly, on the synthetic level,this work demonstrates the possibility to form a homogeneous surfaceanchored with MOF on a transparent conductive surface, whereby theobtained MOF layer is strongly bound to the substrate and postsyntheticchemical modifications are enabled without any loss of material. Furthermore,the obtained material is proven to exhibit an efficient visible-light-drivenphotodegradation activity in aqueous solution.

Formation of tunable cobalt-based hybrid lamellar nanosheets using a bottom-up approach.

Metal-organic frameworks (MOFs) show promise forthe captureof greenhouse gases. To be used at a large scale in fixed-bed processes,their shaping under a hierarchical structure is mandatory and remainsa major challenge, while keeping available their high specific surfacearea. For that purpose, we propose herein an original method basedon the stabilization of a paraffin-in-water Pickering emulsion bya fluorinated Zr MOF (UiO-66(F4)) with polyHIPEs (polymers from highinternal phase emulsions) strategy consisting of the polymerizationof monomers in the external phase. After polymerization of the continuousphase and elimination of the paraffin, a hierarchically structuredmonolith is obtained with the UiO-66(F4) particles embedded in thepolymer wall and covering the internal porosity. To avoid the poreblocking induced by the embedment of the MOF particles, our strategywas to modify their hydrophilic/hydrophobic balance with a controlledadsorption of hydrophobic molecules (perfluorooctanoic acid, PFOA)on the UiO-66(F4) particles. This will induce a displacement of theMOF position at the paraffin-water interface in the emulsionand then make the particles less embedded into the polymer wall. Thisleads to the formation of hierarchically structured monoliths integratingUiO-66(F4) particles with higher accessibility, maintaining theiroriginal properties and allowing their application in fixed-bed processes.This strategy was demonstrated by N-2 and CO2 capture, and we believe that such original strategy could be appliedto other MOF materials.

This work reports the effect of Pd(II) as chemical effector on an acylhydrazone-based dynamic covalent library (DCL) in biphasic systems (water/chloroform). The constituents of the DCL are self-built and distributed in the two phases, two of them are lipophilic enough to play the role of a carrier agent that may transfer Pd(II) from the aqueous phase to the organic phase. Upon addition of Pd(II), the DCL of components exhibits a strong amplification of the constituent that is the most adapted to stabilize Pd(II) in chloroform as well as its agonist in water. This evolution is driven by the combination of the interaction of the DCL with Pd(II) and the presence of the two phases. This study paves the way to a novel approach for liquid/liquid extraction and metal recovery by means of adaptive extractant species generated in situ by a DCL. Pd(II) acts as a chemical effector on an acylhydrazone-based dynamic covalent library (DCL) in a biphasic system. The introduction of Pd(II) leads to a significant increase in the constituent that is best suited for a transfer of Pd(II) into the organic phase. This study introduces a novel approach for liquid/liquid extraction and metal recovery by utilizing extractant species generated in situ by the DCL.image

A (NiMnCo)-Metal-Organic Framework and its oxidized and pyrolysed derivatives have been tested as electrode materials for lithium-ion batteries. Materials have been fully characterized by Scanning Electron Microscopy (SEM), powder X-Ray Diffraction (XRD), Thermogravimetric Analyses (TGA), Infrared (IR) spectroscopy and electrochemical properties have been determined in coin cells using lithium metal as the counter electrode. Studies have revealed specific capacities of 860 mAh g −1 and 800 mAh g −1 at 15 mA g −1 respectively for the MOF and the oxide (690 and 190 mAh g −1 after 50 cycles) whereas the corresponding pyrolysed compound has shown limited electrochemical performances. Ex situ XRD has been performed to highlight the evolution of the material structure during cycling. These results show that electrochemical storage is based on a conversion reaction.

MOFs (Metal-Organic Frameworks) are crystalline porous organic/inorganic hybrid materials with well-defined structures that have proven to possess a great potential in many applications, mostly because during the synthesis of these materials the structure can be controlled to add the desired functionality in either the metal cluster or the linker. Unfortunately, few methods are reported to shape these materials as manipulable and, most importantly, to retain their original properties. Recently, 3D printing of MOF has been proposed and shows promising properties to obtain an object, which can be designed upon request. We propose here to summarize the main development of 3D printing of MOF to determine some prospects and opportunities in this area.

Liquid???liquid extraction processes, characterized on-line by instrumented microfluidic plat-form, significantly enhance the development of predictive thermodynamic models, such as ienaics, and lay the foundations for new approaches to improve kinetic models which combine transport and chemistry. Instrumented microfluidics enables precise measurement of free energy of transfer of species at equilibria and their associated characteristic transfer times, faster and more accurately than its batch mode counterpart. Computer controlled and fully automatized, our platform illustrated the kinetic differences of high extraction???s of Ytterbium (Yb) and Iron (Fe), two elements reported as having very different extraction efficiencies due to different molecular forces competing with com-plexation when modifiers are used together with extractants. Once collected and processed, the ki-netics show two distinct behaviors of these two metallic elements: depending on the temperature, Fe could display a very slow extraction profile when compared to Yb.

Uranium(VI) and thorium(IV) extraction from nitrate media with N,N'-dimethyl,N,N'-dibutylteradecylma lonamide (DMDBTDMA) and N,N,N',N'-tetrahexylmalonamide (THMA) in toluene has been investigated. These two diamides are structural isomers, differing only in the position of alkyl chain substituents. With both ligands, the extraction of uranium(VI) and thorium(IV) is more efficient at higher acidity while uranium(VI)/thorium(IV) selectivity is higher at lower acidity, particularly with DMDBTDMA, for which an almost selective extraction of uranium(VI) has been observed. The selectivity difference between the two ligands has been proven to be mainly due to thorium(IV) extraction, which is strongly dependent on the malonamide molecular structure. On the other hand, uranium(VI) extraction follows the same trend with both DMDBTDMA and THMA. In-depth analysis of molecular and supramolecular features of extracting organic solutions suggests that the disparity of thorium(IV) extraction trends between the two malonamides can be linked to the difference in thorium(IV)-ligand interactions: thorium(IV) extraction appears to lead to rather stable classical coordination complexes with THMA, and more complex supramolecular species with DMDBTDMA. Altogether, these results suggest the prevalence of hydrophobic driven interactions for extraction of metallic cations with DMDBTDMA and electrostatic driven interactions in the case of THMA. (C) 2022 Elsevier B.V. All rights reserved.

Upcycling enables the recycling efforts of E-waste to be more feasible and economically viable. Photovoltaic (PV) energy adoption has increased drastically over the years and is expected to become a mainstream energy source for the future due to its sustainability. However, waste management remains a problem as the PV panels gradually reach their end-of-life and start piling up. Many recycling strategies have been executed, but upcycling efforts to form high-value products from these PV panels are underexplored. In this paper, we report three different synthetic routes to generate metal-organic framework (MOF), MIL-53(Al) (Mat ' eriaux de l' Institut Lavoisier (MIL)), with the polymeric backsheet and aluminum that can be derived from solar panels. The synthesized MOFs have been evaluated in terms of their morphologies, thermal stability, crystallinity, and specific surface areas. Brunauer-Emmett-Teller (BET) surface areas of 1004 m2 g 1 to 1231 m2 g 1 were recorded across the synthesized MOFs. The MOFs were evaluated for their ability to adsorb commonly used harmful dyes, specifically cationic dye Methylene Blue and anionic dye Methyl Orange. The adsorption performances on MB and MO of assynthesized MOFs were determined to be ranging from 190.1 to 262.5 mg g 1 and 244.5-296.7 mg g 1 respectively, demonstrating the potential of upcycling solar panels waste to valuable metal-organic framework for wastewater remediation. The findings pave the way for utilising solar panel electronic waste as a valuable resource for upcycled applications.

A more sustainable management of natural resources and the establishment of processes allowing a joint management of nuclear materials to avoid their diversion from their civilian use are two issues for the nuclear industry. Short alternatives to existing processes have therefore been proposed based on known systems available, tributylphosphate (TBP), for the separation of actinides by liquid/liquid extraction. Proof of concept of such alternative has been established on the uranium(VI)/thorium(IV) system. From an organic phase consisting of a mixture of TBP/n-dodecane loaded with uranium and thorium, two fluxes have been obtained: the first contains almost all of the thorium in the presence of uranium in a controlled ratio, the second contains surplus uranium. Two levers were selected to control the spontaneous separation of the organic phase: the addition of concentrated nitric acid, or the temperature variation. Best results have been obtained using a temperature drop in the liquid/liquid extraction process, and variations in process conditions have been studied. Final metal recovery and solvent recycling have also been demonstrated, opening the door for further process development.

Palladium isolation and refining through solvent extraction suffer from limited stability of commercial reagents or limited availability of robust reagents in nitrate media. Several performing extraction solvents based on diamide reagents have been proposed, but their preparation requires synthetic chemistry skills. In the present work, we propose the use of readily accessible N,N,N',N'-tetrahexylmalonamide (THMA). This reagent revealed superior distribution ratios and selectivity in comparison with previously used diamides for palladium(II) extraction from nitrate media in the frame of palladium recovery from waste. Furthermore, the benefit of excess dihexylamine (DHA) employed during the preparation of THMA was demonstrated through a gain in kinetics performance. Detailed analysis enabled to determine the best performing formulation of extraction solvent, which can be readily prepared from commercially available chemicals without any complex synthesis procedure nor purification step.

E-waste generated from end-of-life spent lithium-ion batteries (LIBs) is increasing at a rapid rate owing to the increasing consumption of these batteries in portable electronics, electric vehicles, and renewable energy storage worldwide. On the one hand, landfilling and incinerating LIBs e-waste poses environmental and safety concerns owing to their constituent materials. On the other hand, scarcity of metal resources used in manufacturing LIBs and potential value creation through the recovery of these metal resources from spent LIBs has triggered increased interest in recycling spent LIBs from e-waste. State of the art recycling of spent LIBs involving pyrometallurgy and hydrometallurgy processes generates considerable unwanted environmental concerns. Hence, alternative innovative approaches toward the green recycling process of spent LIBs are essential to tackle large volumes of spent LIBs in an environmentally friendly way. Such evolving techniques for spent LIBs recycling based on green approaches, including bioleaching, waste for waste approach, and electrodeposition, are discussed here. Furthermore, the ways to regenerate strategic metals post leaching, efficiently reprocess extracted high-value materials, and reuse them in applications including electrode materials for new LIBs. The concept of "circular economy" is highlighted through closed-loop recycling of spent LIBs achieved through green-sustainable approaches.

An Al-based Metal-Organic Framework (MOF) obtained from Li-ion battery wastes as an upcycled mate-rial has been shaped as a hierarchically porous solid monolith. This original method is based on the sta-bilization of a Pickering High Internal Phase Emulsion (HIPE) by MOF particles that conducts to the formation of a monolith after polymerization of the aqueous continuous phase and elimination of the organic internal phase of the emulsion. The presence of a small amount of additive polymers rigidifies the monolith structure and an adhesive binder is used to improve the final network porosity of the mate-rials by creating pore throats. This makes the MOFs accessible at the internal surface of the monolith after shaping and keeps some of their original properties. A screening of the different parameters is proposed to optimize the ratio MOF/Polymer/Adhesive binder and retains at best the original properties of the MOFs. This work shows the great ability of MOFs to stabilize Pickering emulsions and to conduct to a solid polymer-MOF composite monolith with interesting properties. We assume that this method can be generalized to other MOFs materials. (c) 2021 Elsevier B.V. All rights reserved.

End-of life Li-ion batteries can be a source of valuable materials to rebuild new batteries or for other applications. In this way, we propose to precipitate metals from a dissolution solution of Li-ions batteries (LiBs) as hybrid organic-inorganic materials (metal-organic frameworks, MOFs), well known in many fields due to their specific properties (high porosity, large surface area and sometimes thermal and chemical stability). From raw LiBs containing Al, Cu, Mn, Ni, or Co mainly, a selective precipitation of different metals as MOFs has been possible. The use of a carboxylate ligand allowed complete precipitation of Al from the solution, whereas using a bipyridine ligand changes the selectivity to precipitate Cu as MOFs. This work shows that formation of different MOFs in a multi-metallic solution can be obtained depending on the precipitating agent. (C) 2020 Elsevier B.V. All rights reserved.