Significant progress of grain boundary diffusion process for cost-effective rare earth permanent magnets: A review

Waste electrical and electronic equipment (WEEE) is the fastest growing type of waste globally and is an important challenge due to its heterogeneity, intrinsic toxicity and potential environmental impact. However, WEEE also represents an important secondary source of critical and valuable elements and must be viewed as a resource within the context of a circular economy. The use of ionic liquids (ILs) to recover metals from WEEE is reviewed with a special emphasis on the use of ILs in leaching and solvent extraction processes. The advantages of ILs as a reaction medium compared to existing conventional solvents lies in their tuneability and potential environmental benefits. Many studies have used ILs for the selective extraction and purification of metals from WEEE, particularly from waste fluorescent lamp phosphor and batteries containing rare-earth elements with promising results. However, significant barriers remain to the commercial use of ILs for treating WEEE and key barriers to progress ar...

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Recovery of metals from waste electrical and electronic equipment (WEEE) using unconventional solvents based on ionic liquids

For the development of sustainable and efficient separation technology for rare earth elements (REEs), the ionic liquid-type saponification strategy is first put forward in this paper. The extraction mechanism of [trihexyl(tetradecyl)phosphonium][sec-octylphenoxy acetate] ([P6,6,6,14][SOPAA]) prepared by ionic liquid-type saponification for Y(III) was indicated to be ion association. The mechanism contributes to avoiding the numerous saponification procedures and resulting saponification wastewater in the REE separation industry. Load capacity and stripping properties of [P6,6,6,14][SOPAA] reveal advantages over its precursory sec-octylphenoxy acetic acid (HSOPAA). Extractability and selectivity of [P6,6,6,14][SOPAA] for Y(III) are pronouncedly better than those of HSOPAA. Multistage extraction using functional ionic liquid as extractant for different REE separations is developed. After five stages of extraction sections and four stages of scrubbing sections, Lu(III) was successfully separated from Y(III)...

The Sustainable and Efficient Ionic Liquid-Type Saponification Strategy for Rare Earth Separation Processing

This article presents an ecologically safe aqueous two-phase system based on poly(ethylene oxide) with a molecular weight of 1500, designed for complex extraction of Ni(II), Co(II), Fe(III), Mn(II), Zn(II), Cu(II), and Al(III) from nitrate solutions. A kinetic dependence has been investigated for a distribution ratio for the metals examined. The influence of pH-values, temperature, initial metal concentration, and nitric acid content have on the extraction of a wide range of metals in the heterogeneous poly(ethylene oxide) 1500-NaNO3-H2O system has been discovered. As a result, the complex extraction of metals (EMe > 60%) was achieved in one step of extraction without introducing additional chemicals into the system.

https://www.mdpi.com/1420-3049/24/22/4078/pdf

Complex Extraction of Metals in an Aqueous Two-Phase System Based on Poly(Ethylene Oxide) 1500 and Sodium Nitrate.

Insights into coacervative and dispersive liquid-phase microextraction strategies with hydrophilic media - A review.

The recovery of rare-earth metals from waste materials is very important due to the risks associated with having a low supply of them in the future. In this work, hydrophobic 1-alkylcarboxylic acid-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids, [(CH2)nCOOHmin][Tf2N] (n = 3, 5, 7), were synthesized and used to separate neodymium (III) from Fe(III) and samarium (III) from Co(II) in aqueous solutions. The factors affecting the solvent extraction process such as phase volume ratio, contact time, pH value of the aqueous phase, alkyl chain length of the ionic liquids, and temperature of the system were examined systematically. It was found that the maxmium extraction efficiency of the investigated metal ions was as high as 99%, and Sm(III) and Nd(III) could be selectively separated from Co(II) and Fe(III), with separation factors of 104–105, by simply modulation of the aqueous phase pH. After extraction, about 97% of the metal ions could be stripped from ionic liquid phase in a single stri...

Jiao Ren

Papers

pH-Controlled Selective Separation of Neodymium (III) and Samarium (III) from Transition Metals with Carboxyl-Functionalized Ionic Liquids

Choline derivative ionic liquids-based aqueous two-phase systems: Phase diagrams and partition of purine alkaloids