Lithium-ion battery is a mature technology that is used in various electronic devices. Nowadays, this technology is a good candidate as energy storage for electric vehicles. Therefore, much research is focused on the development of high-density power lithium-ion batteries. Government regulations force manufacturers to recycle the batteries for safety and health reasons but recycling could also be interesting from an economic viewpoint since cathodes in lithium-ion batteries contain valuable metals. The electrodes in lithium-ion batteries will evolve to provide more energy and the recycling processes will have to fit with this evolution. Leaching, bioleaching and solvent extraction are at the centre of these processes. In this paper, recent leaching and solvent extraction strategies for recovering valuable metals from spent lithium-ion batteries are reviewed and the evolution of these processes is discussed.

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Facilitated transport through polymer inclusion membranes (PIMs) is a promising method for simultaneous separation and removal of valuable and toxic metal ions from aqueous solutions. Recently, ionic liquids (ILs) have been used as extracting agents for metal ions due to their unique physicochemical properties. This paper presents research on the facilitated transport of cadmium(II) and copper(II) ions from aqueous chloride solutions through PIMs with phosphonium ILs as new selective ion carriers. Cellulose triacetate membranes containing o-nitrophenyl octyl ether (ONPOE) as a plasticizer and Cyphos IL 101 [trihexyl(tetradecyl)phosphonium chloride] or Cyphos IL 104 [trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate] as the ion carriers have been prepared and applied for investigations. Cd(II) ions were transported preferably from hydrochloric acid solutions containing Cu(II) ions through the PIMs. Higher selectivity coefficient of Cd(II) over Cu(II) (SCd/Cu) from 0.1 mol·dm−3 hydrochloric acid was obtained for PIM with Cyphos IL 104 as the ion carrier. The influence of HCl and NaCl concentrations in the source phase on metal ion transport across PIM doped with Cyphos 104 was studied. It was found that the initial fluxes of Cd(II) and Cu(II) increase with increasing chloride ions concentration in the source phase. The selectivity coefficient for Cd(II) over Cu(II) decreases with increasing HCl concentration in the source phase. The results suggest that the separation system presented in this paper can be useful for the removal of Cd(II) from acidic chloride solutions in the presence of Cu(II).

AbstractThis paper analyzes the applications of various ionic liquids (ILs) as metal ion carriers and extractants utilized for the separation of metal cations from aqueous solutions. Subsequently, an up-to-date review of the use of ILs in polymer inclusion membranes is presented. ILs represent a promising group of extractants and ion carriers of metal ions in extraction and membrane separation processes. The removal of heavy metals ions from aqueous solutions using ILs indicates an extensive and promising research area. It is expected that the role of ILs will gradually increase as the worldwide implementation of separation methods in recovery of metal ions from various aqueous solutions is growing quickly.

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This work focuses on the application of polymer inclusion membrane (PIM) with tricaprylmethylammonium thiosalicylate, [A336][TS] (TOMATS), a thiol-containing task-specific ionic liquid for the transport of Pd(II) ions from aqueous solutions. 0.3 M thiourea in 0.1 M hydrochloric acid was found the most effective stripping phase in the transport of Pd(II) from membrane phase containing TOMATS. Separation of Pd(II) ions was also carried out from hydrochloric acid solution containing Pt(IV), Fe(III), Ni(II), and Mn(II). Pd(II) ions were preferably transported in the presence of these metal ions. The separation coefficients followed the order:[TS] proved to be an excellent ion carrier for Pd(II) from hydrochloric acid solution. The results also showed that transport efficiency of the PIM was reproducible and it can be useful for the development of the simple and highly effective method of Pd(II) recovery from leach liquor of spent catalysts.

Selective solvent extraction of zinc(II) and copper(II) from aqueous acidic chloride solutions by mixture of bis(2,2,4-trimethylpentyl)phosphinic acid (Cyanex 272) and trioctymethylammonium chloride (Aliquat 336) in kerosene has been investigated. Detailed studies have been conducted by varying pH, hydrochloric acid and chloride concentrations in aqueous phase as well as extractants concentration in organic phase. A full and high selective solvent extraction of zinc(II) over copper(II) from acidic chloride solutions has been achieved by 0.1 M Cyanex 272 and 0.06 M Aliquat 336 in kerosene while efficient Zn(II) stripping has been performed by using 1 M sulphuric acid. The following selectivity coefficients of zinc(II) over Cu(II) (S Zn/Cu ) during their A c c e p t e d M a n u s c r i p t 2 solvent extraction from 1 M NaCl at pH 0.5 by Cyanex 272, Aliquat 336 and their mixture were found to be equal to: 1.7, 62 and 3162, respectively.

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