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The continued electrification of society and the related growing demand for rechargeable batteries require in turn the elaboration of efficient and sustainable recycling strategies for their recovery and valorization. An important separation relevant to nickel metal hydride (NiMH) and lithium-ion battery recycling is the intertransition element separation between Ni(II), Co(II), and Mn(II). In this work, a fully aqueous process for the recovery of Mn(II) and Co(II) from concentrated Ni(II) effluents typical of NiMH battery leachate is disclosed consuming only Na2CO3. In the first instance, Mn is selectively precipitated as Mn(IV) by oxidation using ozone as an oxidant, resulting in a significant enrichment of Mn in the precipitate relative to its original solution concentration. Second, a thermo- and acid-responsive aqueous biphasic system (ABS) based on the ionic liquid (IL) tributyltetradecylphosphonium chloride ([P44414]Cl) and NiCl2 was used to recover Co(II). By using the high NiCl2 content found in NiMH leachates both as the ABS phase former and salting-out agent, no additional salt is required. Through careful manipulation of the Co(II) to Ni(II) and the IL to Co(II) molar ratios, an effective and selective separation of Co(II) from Ni(II) was achieved. Finally, Co(II) is precipitated from the IL-rich phase and the IL is regenerated in one step by the addition of Na2CO3 to induce a new phase separation. published

International audience; This paper discusses the feasibility of tantalum electrodeposition carried out under potential control from 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [BMPyr][TFSI] room temperature ionic liquid electrolyte containing tantalum pentafluoride (TaF5). The influence of electrode nature, electrolyte temperature and electrolysis duration on the morphology, the adherence, the thickness and the crystalline properties of tantalum deposits is reported. The obtained tantalum deposits are analyzed by SEM, XRD, Raman spectroscopy and XPS surface analytical techniques. Pulsed potential electrodeposition is investigated in order to enhance deposit properties. Post electrodeposition thermal treatments are also reported.

An acidic aqueous biphasic system (AcABS) presenting a desired and reversible phase transition with HNO3 concentration and temperature was developed herein as an integrated platform for metal separation. The simple, economical, and fully incinerable (C,H,O,N) AcABS composed of tetrabutylammonium nitrate ([N4444][NO3])+HNO3 +H2O was characterized and presented an excellent selectivity towards CeIV against other rare earth elements and transition metals from both synthetic solutions and nickel metal hydride (NiMH) battery leachates. The acid-driven self-assembly of AcABS bridges the gap between traditional ABS and liquid-liquid extraction whilst retaining their advantageous qualities, including compatibility with highly acidic solutions, water as the primary system component, the avoidance of organic diluents, rapid mass transfer, and the potential integration of the leaching and separation steps. published

International audience; 18 Starting from a real Proton Exchange Membrane Fuel Cell (PEMFC) leachate, separation of the 19 strategic metals platinum(IV) and cobalt(II) was carried out using two distinct strategies applying ionic 20 liquids (ILs), either via solvent extraction (SX) or acidic aqueous biphasic system (AcABS). The 21 versatility of ILs and their ability to provide original solutions to common issues in the field of used 22 device recycling is illustrated, with both approaches critically compared. The highly hydrophobic 23 tetradecylpyridinium bis(trifluoromethanesulfonyl)imide ([C 14 pyr][NTf 2 ]) was synthesized and applied 24 to the separation of Pt/Co. This solvent was able to selectively extract over 98% of Pt(IV) from the 25 PEMFC leachate in one step while leaving Co(II) in the aqueous phase and exhibited the highest 26 reported partition of Pt(IV) in a [NTf 2 ]-based IL. In a second approach, the AcABS based on the fully 27 water-miscible tributyltetradecylphosphonium chloride ([P 44414 ]Cl), HCl and water, is compatible with 28 the concentrated nature of the leachate and extracts both platinum(IV) and cobalt(II) quantitatively. In 29 a second stage, a selective precipitation step enabled the recovery of platinum(IV) in the form of an 30 organometallic complex whilst leaving the co-extracted cobalt(II) in solution. This work represents the 31 2 first utilization of an AcABS for the recycling of a real waste technological object. These two different 32 types of ILs in both cases resulted in an efficient separation of Pt(IV) from Co(II), using two very 33 different pathways. The merit and transferability of each approach is critically compared, and 34 suggestions are made as to the suitable condition range for each technique. 35 36

International audience; In this work, the important role played by metal ions such as Fe(II/III), Cr(III) and Ni(II) in the formation and binodal behaviour of aqueous biphasic systems (ABS) composed of HCl and the ionic liquid, [P44414]Cl, or the polymer, PEG-600, is investigated. The concentration of metal ions used in this work exceeds several g/L for an industrial foreseen application. Experiments have also been carried out by varying the concentration of metal ions at different temperatures. Fe exhibits a totally different behaviour compared to Ni and Cr. In particular, the binodal curves in presence of the ionic liquid are far from the classical curves found in the literature, displaying an onion-shape form, while for Ni and Cr, the curves follow the classical trend. When any of the three metal ions is mixed with the polymer and HCl medium, only Fe(III) induces a biphasic system. Insights into the chemical driving forces at work are discussed.Introduction In recent years, neutral Aqueous Biphasic Systems (ABS), composed of different polymer-polymer, polymer-salt or salt-salt combinations, plus water as the main protagonist, have been taken into consideration to selectively extract metal ions. In particular, the use of the [P44414]Cl (tri-butyl tetradecyl phosphonium chloride) ionic liquid (IL) or of the polyethene glycol (PEG) polymer for metal extraction has already been the subject of several papers. 1-6 The use of these compounds, more appropriately called biphasic inducers in these classical ABS, helps to make the process eco-sustainable. The [P44414]Cl hydrophilic ionic liquid (i) is less toxic than the respective hydrophobic IL 7 , (ii) can be used in much lower quantities than organic volatile solvents and (iii) the extraction kinetics is favored by its low viscosity. In regards to the PEG, this is an inexpensive, nontoxic, non-flammable compound which is commercially available in very large quantities. These systems are intrinsically much eco-friendlier than the classical liquid-liquid systems where organic solvents are used as main components and could thus be favorably considered by the industry. However, in order to comply with any industrial demand, extraction should proceed from highly loaded wastes, which is currently very rarely the case in the literature. Furthermore, most industrial wastes are highly acidic, which is not compatible with the most classical ABSs. Therefore, in the first step, we took advantage of the recently described Acidic Aqueous Biphasic Systems (AcABS) 8 loaded with very high concentrations of either Cr, Ni or Fe to perform fundamental studies in view of potential industrial applications. In this work, aqueous biphasic systems (ABS) are formed from solutions containing a single metal element, HCl as the acid, and using either [P44414]Cl or PEG as biphasic inducer. We focused on the influence of the metal, in particular on the contribution coming from the type of metal used and on its concentration. Furthermore, the influence of temperature has been taken into consideration for industrial needs. Finally, we reviewed past literature which proposed some possible explanations and we discussed these under the light of our experimental results. Experimental Section Chemicals Polyethene glycol with an average molecular weight of 600 (abbreviated as PEG-600) was acquired from Acros Organics. The ionic liquid tributyl tetradecyl phosphonium chloride, [P44414]Cl, was acquired from Interchim (Montluçon, France). The declared purity was > 95%. Some basic physicochemical properties of PEG-600 are reported in the supplementary materials. The hydrochloric acid, HCl, (37 wt% = 12 mol/L, in water) was acquired from Sigma-Aldrich. The following hydrated salts have been used: NiCl2.6H2O pure at 98% acquired from Rectapur, CrCl3.6H2O pure at 98% acquired from Fluka, FeCl2.4H2O pure at 98% and FeCl3.6H2O pure at 99% were acquired from Merck. All the chemicals were used without further purification. The water used in all experiments was passed through a Milli-Q apparatus purification system commercialized by Merck (18MΩ). AAS (Atomic Absorption Spectroscopy) single element standard solutions (1000 mg/L) were acquired from Perkin Elmer for Cr and from Chem-Lab for Fe and Ni. Sample preparation

Ionic-liquid-based aqueous biphasic systems (IL-based ABS) have demonstrated exceptional performance in bioseparation processes. However, IL-based ABS are of limited interest for metal extraction as most metals are not stable in their neutral or alkaline pH conditions. In the quest for better extraction systems for metals, the development of IL-based ABS with highly acidic solutions (AcABS), induced by the mixture of a hydrophilic IL ([P44414]Cl), a mineral acid (HCl, HNO3 or H2SO4) and water, opens new possibilities. A comprehensive investigation of fundamental aspects of IL-based AcABS was performed, including the temperature dependence of the phase diagrams, tie-lines and ion exchange behavior, evidencing the unique characteristics of these new systems. In particular, the favorable biphasic formation with an increase in temperature showcases the lower critical solution temperature (LCST) behavior of the phosphonium-based IL and opens many possibilities for AcABS application by creating stimuli responsive systems. The anion exchange identified highlights the IL-based AcABS complexity that renders the analytical characterization of the phases mandatory, instead of the traditional method coupling an empirical fit of the binodal with the lever-arm rule. Through judicious selection of the inorganic acid, different extraction systems can be obtained by tuning the degree of anion-exchange, underlining the versatility of the proposed AcABS system.

International audience; This study is focused on the development of environmentally friendly recycling method for selective recovery in a closed loop manner of Co and Pt from Pt3Co/C catalyst used as the PEMFC cathode. Pt and Co selective separation was carried out using two different hydrometallurgical alternatives based either on ion exchange resin or solvent extraction. The recycling process was optimized in order to maximize the platinum recovery yield, which reached 83% and 77% of the Pt initially present in the MEA using respectively solvent extraction or ion exchange resin separation alternatives. The recovered platinum alkaline solutions have been further used for Pt/C particles synthesis via a modified polyol method and it was shown that although the resin alternative resulted in slightly lower recovery yield, the catalyst prepared via this alternative satisfied morphological and electrochemical properties for the oxygen reduction reaction (ORR) by performing similarly to a commercial state-of-art Pt/C catalyst. The feasibility of closed loop Pt/C catalyst recycling was thus proven. The environmental impacts of the two recycling alternatives have been compared using life cycle assessment methodology (LCA) and similar impacts have been found for both alternatives from the point of view of the entire MEA life cycle. The ion exchange resin alternative has thus been selected as the most appropriate one.

This work addresses the surface characterization of an organic salt based on a piperidinium cation and a halide anion, similar to a first generation ionic liquid, using the Inverse Gas Chromatography (IGC) technique. IGC was employed in order to assess the dispersive surface energy and the acid/base character of 1-butyl-1-ethylpiperidinium bromide, [C2C4PIP]Br at a temperature range (313.15–343.15 K) well below its melting point, where the retention mechanism is governed by the surface adsorption of the probes. This type of characterization was possible due to the high melting point of [C2C4PIP]Br, namely 413.15 K. The dispersive component of the surface energy was estimated with the aid of the Schultz method and the Dorris-Gray method. Results obtained using the first method were higher than the ones obtained by the latter. The discrepancy between the two methods was found to increase with the increase of temperature. The acid/base characterization was implemented by using the Flour and Papirer approach as well as the Brookman and Sawyer method. The acidity and basicity constants of the surface of [C2C4PIP]Br revealed that it is amphoteric with a predominantly basic character.

In this work, the aqueous speciation of Rh(III) in chloride medium was investigated by UV-vis spectroscopy for ligand to metal ratios R = (Cl&minus, )/(Rh) ranging from 300 to 5000, at fixed Rh concentration (2.4 &times, 10&minus, 3 M). Under the chemical conditions of this work, no time evolution was observed, which allows for the fitting of the UV-vis data by Principal Component Analysis (PCA) and Multi-Curve Resolution (MCR). From this, and by comparison with literature data, the three independent species [RhCl4]&minus, [RhCl5]2&minus, and [RhCl6]3&minus, were identified, their individual absorption spectra derived and their respective contribution to the collected experimental UV-vis spectra calculated. Then, extraction of Rh(III) towards the ionic liquid trihexyltetradecylphosphonium chloride was performed. Comparison with the speciation data gives insight into the extraction mechanism and the extracted species.

International audience; Cellulose from cotton fibers was functionalized through a dissolution-regeneration process with phosphonate-based ionic liquids (ILs): 1,3-dimethylimidazolium methylphosphonate [DIMIM][(MeO)(H)PO 2 ] and 1-ethyl-3-methylimidazolium methylphoshonate [EMIM][(MeO)(H)PO 2 ]. The chemical modification of cellulose occurred through a transesterification reaction between the methyl phosphonate function of ILs and the primary alcohol functions of cellulose. The resulting cellulose structure and the amount of grafted phosphorus were then investigated by X-ray diffraction, ICP-AES, and 13 C and 31 P NMR spectroscopy. Depending on the IL type and initial cotton / IL ratio in the solution, regenerated cellulose contained up to 4.5% of phosphorus. The rheological behavior of cotton cellulose/ILs solutions and the microscale fire performances of modified cellulose were studied in order to ultimately prepare flame retardant cellulosic materials. Significant improvement in the flame retardancy of regenerated cellulose was obtained with a reduction of THR values down to about 5-6 kJ/g and an increase of char up to about 35 wt%.

International audience; Since the Manhattan Project in the early 1940s, the separation and recovery of metals from solution by solvent extraction has gained a lot of attention and it is nowadays, together with precipitation and ion exchange, one of the three main separation techniques for metals recovery, largely used in mining, nuclear and metallurgical industries as well as in waste water treatment. For years, in the solvent extraction field, the primary objective was to find the "good" solvent-extractant couple in order to develop an efficient separation system for a given metal. This was mainly driven by the fact that the metal resources were rather stable (mainly the richer ores of more or less defined composition). Once this couple was identified , the optimum extraction parameters were searched for. Tremendous efforts have been successfully applied in the adjustment of the extracting phase characteristics, mainly based on the extracting agent/diluent couple, possibly complemented by a phase modifier to avoid third phase formation, a synergist, etc. Considering the rather limited number of suitable organic solvents, most of the work has dealt with fine-tuning of the extracting agent's chemical structure. Based on the latter consideration, solvent extraction systems are traditionally divided into cation exchangers, anion exchangers and neutral extractants. This is related to the extraction mechanism that thus seems mainly, if not entirely, governed by the extracting phase composition. Our world is a changing one and the increase in demand for metals has induced interest in a broader variety of starting materials, where waste electronic equipment (WEE) or ores of poorer grade are now considered as possible starting materials for metal extraction , separation and recovery. Furthermore, environmental regulations have strengthened

This paper reports a comparative study of three methods for determining the surface charge and acid–base behavior of a TiO2 rutile material. Electrophoretic mobility measurements were performed using two different batch protocols: (i) a “static” mode that consisted of immersing the rutile powder in aqueous solutions of given pH's and ionic strengths for 10 h, and (ii) a “dynamic” mode that consisted of using an automatic titrator to continuously adjust the solution pH with a contact time of 15 min. The same apparatus (a Nanosizer from Malvern) was used to measure the zeta potential of the particles in both methods. These batch experiments were next compared to the determination of the surface charge of rutile using nonlinear chromatography in column experiments. In that case, the rutile powder was compacted to enable the formation of a proper column bed. Therefore, Raman scattering and X-ray photoelectron spectra were used, as well as other physical information such as specific surface area and morphology of the particles, to verify that the rutile powder and compacted form were identical. The three approaches were then compared and discussed in relation to the acid–base behavior of the rutile material.

International audience; The morphological structure evolutions of polyoctenamer upon photo-ageing have been monitored with the aim of correlating the changes of the microstructure with our previous results concerning chemical and molecular evolutions. The influence of the experimental temperature of photo-oxidation has been investigated with regard to the melting temperature of the different crystalline microphases. A critical point was clearly exhibited (10 h of UV exposure at 35 °C). Before this point the degradation occurs according an oxidative process and takes place only in the amorphous phases. During this period, the molecular structure changes to induce rapid cross-linking. After the critical point, the chemical oxidation results from a photolytic process. The extent of the tridimensional network becomes invariant and imperfect crystalline zones are then affected.