Effects of structural changes of new organophosphorus cationic exchangers on a solvent extraction of cobalt, nickel and manganese from acidic chloride media

The effects of structural changes of organophosphorus cationic exchangers on metal-distribution curves (extraction efficiency vs. pH) have been investigated for the recovery of cobalt(II), nickel(II) and manganese(II) from acidic chloride solutions. By using alkyl groups with different branching and hydrophobicity and by including oxygen atoms in the hydrophobic chains of the cationic exchangers, it has been shown that the change of the chemical structure in the hydrophobic chains plays an important role in the extraction behaviours and causes more specifically a shift of the extraction curves to higher or lower pH depending on pKa values of extracting agents (evaluated by using QSPR calculations), distribution constants of metal–ligand complexes between organic and aqueous phases and the formation constant of the metal–ligand complexes. Based on the present results, interest in the new cationic exchangers synthesized in the present work for cobalt(II), nickel(II) and manganese(II) separation is also discussed

Interphase chemistry of Si electrodes used as anodes in Li-ion batteries

International audienceThe effect of the Si electrode morphology (amorphous hydrogenated silicon thin films - a-Si:H as a model electrode and Si nanowires - SiNWs electrode) on the interphase chemistry was thoroughly investigated by the surface science techniques: X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). XPS analysis shows a strong attenuation and positive shift of the Si 2p peaks after a complete charge/discharge performed in PC- and EC:DMC-based electrolytes for both electrodes (a-Si:H and SiNW), confirming a formation of a passive film (called solid electrolyte interphase - SEI layer). As evidenced from the XPS analysis performed on the model electrode, the thicker SEI layer was formed after cycling in PC-based electrolyte as compared to EC:DMC electrolyte. XPS and ToF-SIMS investigations reveal the presence of organic carbonate species on the outer surface and inorganic salt decomposition species in the inner part of the SEI layer. Significant modification of the surface morphol- ogy for the both electrodes and a full surface coverage by the SEI layer was confirmed by the scanning electron microscopy (SEM) analysis

Multinuclear solid-state NMR investigation of Hexaniobate and Hexatantalate compounds

This work determines the potential of solid-state NMR techniques to probe proton, alkali, and niobium environments in Lindqvist salts. Na7HNb6O19·15H2O (1), K8Nb6O19·16H2O (2), and Na8Ta6O19·24.5H2O (3) have been studied by solid-state static and magic angle spinning (MAS) NMR at high and ultrahigh magnetic field (16.4 and 19.9 T). 1H MAS NMR was found to be a convenient and straightforward tool to discriminate between protonated and nonprotonated clusters AxH8–xM6O19·nH2O (A = alkali ion; M = Nb, Ta). 93Nb MAS NMR studies at different fields and MAS rotation frequencies have been performed on 1. For the first time, the contributions of NbO5Oμ2H sites were clearly distinguished from those assigned to NbO6 sites in the hexaniobate cluster. The strong broadening of the resonances obtained under MAS was interpreted by combining chemical shift anisotropy (CSA) with quadrupolar effects and by using extensive fitting of the line shapes. In order to obtain the highest accuracy for all NMR parameters (CSA and quadrupolar), 93Nb WURST QCPMG spectra in the static mode were recorded at 16.4 T for sample 1. The 93Nb NMR spectra were interpreted in connection with the XRD data available in the literature (i.e., fractional occupancies of the NbO5Oμ2H sites). 1D 23Na MAS and 2D 23Na 3QMAS NMR studies of 1 revealed several distinct sodium sites. The multiplicity of the sites was again compared to structural details previously obtained by single-crystal X-ray diffraction (XRD) studies. The 23Na MAS NMR study of 3 confirmed the presence of a much larger distribution of sodium sites in accordance with the 10 sodium sites predicted by XRD. Finally, the effect of Nb/Ta substitutions in 1 was also probed by multinuclear MAS NMR (1H, 23Na, and 93Nb)

Simulation of Solvent Extraction Flowsheets by a Global Model Combining Physicochemical and Engineering Approaches-Application to Cobalt(II) Extraction by D2EHPA

International audienceThe liquid-liquid extraction of cobalt(II) from an acidic chloride solution by using bis-(2ethylhexyl) phosphoric acid (D2EHPA) diluted in kerosene has been modelled by means of a combination of physicochemical and engineering approaches. This model is able to calculate the performance of solvent extraction flowsheets (residual fraction at the outlet of the flowsheet and concentration factor between the feed solution and eluate) as a function of pH, leach solution flowrate, solvent flowrate and stripping solution flowrate. The influence of these parameters and mixer-settlers arrangements on the performance of eleven flowsheets is discussed

Les sels de lithium, à la base du stockage d'électricité

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Recent Advances in Hydrometallurgy for the Development of a Sustainable Production of Lithium-Ion Batteries

International audienceIt is expected that the small world of lithium will boom due to the emergence of electric vehicles. Likewise, it is expected that the demand in cobalt and nickel will be increased by 31% and 69% between 2017 and 2030, respectively. The development of sustainable and economic processes to recover lithium, cobalt, nickel and manganese from primary and secondary resources is therefore of great importance, especially because of a huge demand of these metals to produce lithium-ion batteries. This paper gives recent advances in the development of hydrometallurgical processes for the sustainability of battery raw materials

Advances in Hydrometallurgy

The development of new technologies and the increasing demand of mineral resources from emerging countries are responsible for significant tensions in the price of non-ferrous metals [...

Proceedings of the First Global Conference on Extractive Metallurgy CO-EDITORS

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