Special Issue "Solvent Extraction of Critical Metals"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 31 May 2018

Special Issue Editors

Guest Editor
Assist. Prof. Ana Paula Paiva

Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal
Website | E-Mail
Interests: liquid–liquid (solvent) extraction in hydrometallurgy; synthesis and characterization of organic extractants; extraction of platinum-group metals (platinum, palladium, rhodium and ruthenium), silver and iron from chloride media; hydrometallurgical recycling of end-of-life materials, e.g., spent catalysts
Co-Guest Editor
Prof. Gérard Cote

PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris (UMR 8247), 11, rue Pierre et Marie Curie 75231 Paris Cedex 05, France
Website | E-Mail
Interests: urban mining, WEEE, nuclear fuel cycle, hydrometallurgy, solvent extraction, critical metals

Special Issue Information

Dear Colleagues,

Critical metals are those included in materials that are indispensable to modern life and for which an exponential increase in consumption is already a reality or will be in a short-term perspective. Current technologies involved in the manufacture of electrical and electronics equipment (EEE), photovoltaic cells, batteries, and catalysts intimately rely on the activity and function of some metals. For instance, tantalum, indium and ruthenium are key feedstocks for EEE; gallium, tellurium and germanium for photovoltaic cells; cobalt and lithium for batteries; and platinum-group and rare-earth metals for automotive and industrial catalysts.

To fulfil the requests of developed society, the scarcity of some of the above-mentioned metals in primary supply resources has to be conveniently balanced with recycling practices. In fact, the concentrations of some metals in those end-of-life materials are 100 times higher than in their natural ores. Accordingly, the reduction of the overall environmental impacts linked with the life cycles of the critical metals, together with their intrinsic value-adding benefits, favourably contribute to an important increase of resources efficiency. Although some industrial recycling circuit facilities are apparently well established, research and development of technical procedures involving novel recycling and refining concepts for these strategic metals are always welcome.

Nowadays, solvent extraction (SX) is a mature unit operation applied to separate, purify and concentrate metals from leaching solutions when a hydrometallurgical route is considered. This Special Issue aims to address the latest research devoted to exploring the potentialities of commercial or specifically synthesized extractants in the design of SX processes to efficiently and selectively recover critical metals from complex secondary materials leaching media. Advances in alternative separation techniques whose functioning relies on SX principles are also welcome. Research articles focusing on the development of integrated environmentally-friendly and cost-effective hydrometallurgical processes to recuperate critical metals are encouraged as well.

Assist. Prof. Ana Paula Paiva
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.


  • Secondary materials
  • Spent catalysts and electronic scrap
  • Recycling practices
  • Critical and strategic metals
  • Hydrometallurgy
  • Complex leaching solutions
  • Solvent extraction
  • Commercial or synthesized extractants

Published Papers (1 paper)

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Open AccessFeature PaperReview Recycling of Palladium from Spent Catalysts Using Solvent Extraction—Some Critical Points
Metals 2017, 7(11), 505; doi:10.3390/met7110505
Received: 15 September 2017 / Revised: 3 November 2017 / Accepted: 9 November 2017 / Published: 16 November 2017
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Electrical and electronics equipment and automotive and industrial catalysts are some examples of top technological devices whose functioning rely on the use of platinum-group metals (PGMs). The PGMs’ high economic value and difficult to replace technological properties, together with their scarcity in the
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Electrical and electronics equipment and automotive and industrial catalysts are some examples of top technological devices whose functioning rely on the use of platinum-group metals (PGMs). The PGMs’ high economic value and difficult to replace technological properties, together with their scarcity in the Earth’s crust, justify concerns about their critical condition and reinforce the importance of developing recycling practices for PGM end-of-life materials. This article presents and discusses recent advances regarding the use of hydrometallurgical solvent extraction to recover one PGM, palladium, from spent catalysts. Two different tendencies are implicit in the literature concerning Pd(II) extraction: a few groups focus on the adjustment and optimization of current commercial extractants, while others prefer to design new extracting compounds. Actually, the leach solutions obtained from the treatment of anthropogenic materials generally exhibit different compositions when compared to those coming from the primary resources. The pros and cons of both approaches are critically discussed, and the assumptions backing some of the reported achievements are also appraised. Full article
(This article belongs to the Special Issue Solvent Extraction of Critical Metals)

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