Topic Editors

Department of Inorganic Chemistry, University of Chemical Technology and Metallurgy, Sofia, Bulgaria
Materials Sciences Research Center, Japan Atomic Energy Agency (JAEA), Hyogo, Japan

Green Twist in Solvent Extraction and Separation of Metal Species

Abstract submission deadline
closed (31 October 2023)
Manuscript submission deadline
closed (31 December 2023)
Viewed by
4169

Topic Information

Dear Colleagues,

The aim of this topic is to provide an original and unique environment for researchers in academia and especially in industry to share and discuss their cutting-edge results of all novel approaches including ionic liquids, covering their in-depth characterization and/or modelling with the respect of the green scope, to their potential applications, not only in the liquid metal extraction and separation chemistry. The global objective is to propose so far unexplored and versatile new strategies: the optimization of the aqueous-biphasic systems composed of water (or not) and an organic phase incorporating “green” extracting moiety/moieties dissolved in different adopted media. Needless to say, these dissimilar “liquid compounds” possess unique chemical properties useful for a wide range of applications in various fields as diverse as solvent extraction, hydrometallurgy, environmental remediation and nuclear sciences, chemical engineering technology, metallurgy and recycling pinpointed the green concept, energy storage, biotechnology, etc. On the other hand, the design of original molecules has a long history in the analytical and solvent extraction chemistry of metal ions, with synthesized multicentre ligands, possessing high extraction efficiency and having a unique chemical structure. In all the presented studies, it is highly appreciated if the environmental gain is clearly outlined.

Dr. Maria Atanassova
Dr. Kojiro Shimojo
Topic Editors

Keywords

  • ionic liquids
  • green separation
  • lanthanoids
  • chelating ligands
  • modernized concepts
  • unusual reagents
  • recycling of valuable metals
  • sustainable liquid media
  • ion exchange
  • cutting edge methods
  • analytical solutions
  • advanced extraction mechanism
  • circular economy
  • green infrastructure

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Analytica
analytica
- - 2020 15.6 Days CHF 1000
Membranes
membranes
4.2 4.4 2011 13.6 Days CHF 2700
Molecules
molecules
4.6 6.7 1996 14.6 Days CHF 2700
Polymers
polymers
5.0 6.6 2009 13.7 Days CHF 2700
Separations
separations
2.6 2.5 2014 13.6 Days CHF 2600

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Published Papers (3 papers)

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17 pages, 3326 KiB  
Article
New Sustainable Solvent Extraction Pathways for Rare Earth Metals via Oximes Molecules
Molecules 2023, 28(22), 7467; https://doi.org/10.3390/molecules28227467 - 07 Nov 2023
Viewed by 619
Abstract
A study on the synergistic extraction of Eu(III) ions with a series of chelating ligands and determination of the process parameters is presented by employing ionic liquids and typical organic diluents. The investigations of the liquid–liquid extraction, commonly applied in the separation science [...] Read more.
A study on the synergistic extraction of Eu(III) ions with a series of chelating ligands and determination of the process parameters is presented by employing ionic liquids and typical organic diluents. The investigations of the liquid–liquid extraction, commonly applied in the separation science of 4f and 5f-ions acidic chelating compounds, 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP), 4-benzoyl-3-phenyl-5-isoxazolone (HPBI), and 2-thenoyltrifluoroacetone (HTTA) alone and in combination with two synergistic agents, meso-hexamethylpropyleneamine oxime (S2: HM-PAO) and its bis-imine precursor (S1: pre-HM-PAO), are presented. The interaction between the two extractants (acidic/neutral) in deuterochloroform was studied using 1H, 13C, and 1H-1H NOESY experiments. Several conclusions are given highlighting the role of the ionic diluent in complexation processes and selectivity with an employment of the two synergistic agents for various metal s-, p-, d-, and f-cations in the Periodic table, with almost 25 metal ions. The objective was to optimize a system for 4f-ions solvent extraction based on the new oxime molecules with β-diketone/isoxazolone/pyrazolone partnership. As detailed above, slight enhancements of extraction efficiencies were obtained either by using basic synergistic agents such as HM-PAO and/or using pre-HM-PAO. A competitive solvent extraction test of nearly 18 f-ions by various ligands (HTTA, S1, S2, and HPBI) and the two mixtures HTTA−S1 and HTTA−S2 diluted in ILs or organic diluents was also conducted in order to evaluate the switchable diluent impact. Additionally, electron paramagnetic resonance (EPR) spectroscopy was used to study the established chemical species with Cu2+ cations in the obtained organic extracts involving the two synergistic molecules. Full article
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12 pages, 1367 KiB  
Article
Mutual Solubilities between Ethylene Glycol and Organic Diluents: Gas Chromatography and NMR
Molecules 2023, 28(13), 5121; https://doi.org/10.3390/molecules28135121 - 29 Jun 2023
Viewed by 1213
Abstract
In this work, the mutual solubilities of sets of organic diluents (CHCl3, C6H6, C2H4Cl2, CCl4, C6H12, and n-hexane) with the organic compound ethylene glycol are [...] Read more.
In this work, the mutual solubilities of sets of organic diluents (CHCl3, C6H6, C2H4Cl2, CCl4, C6H12, and n-hexane) with the organic compound ethylene glycol are investigated via gas chromatography (GC). The experimental data measured for these binary organic systems are used to adjust the future nonaqueous systems for the solvent extraction of various metals with ligands. The obtained results showed that the solubility of ethylene glycol decreased in the order CHCl3 > C6H6 > C2H4Cl2 > CCl4(0%) ≈ C6H12 ≈ n-hexane. On the other hand, the solubility of the tested traditional organic diluents in ethylene glycol decreased in the following order: C6H6 > CHCl3 > C2H4Cl2 > n-hexane > C6H12 > CCl4. 1H NMR was also used as an analytic method in order to compare the obtained results for the samples showing significant solubility only, including an additional study with 1,2- or 1,3-propanediol. The enhanced solubility of the C6H6 compound in ethylene glycol was identified here as critical due to the GC technique, which will be without future consequences in chemical technology. Therefore, it was found that the best molecular diluent for the recovery of metals among the tested ones is C6H12, with a green protocol as the new paradigm, replacing the aqueous phase with another nonaqueous phase, i.e., a second organic diluent. Full article
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19 pages, 4166 KiB  
Article
Improvement of Gd(III) Solvent Extraction by 4-Benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one: Non-Aqueous Systems
Separations 2023, 10(5), 286; https://doi.org/10.3390/separations10050286 - 03 May 2023
Cited by 1 | Viewed by 1388
Abstract
The study of the liquid–liquid extraction of gadolinium (Gd(III) ion) with a chelating compound, 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP), and the determination of the process parameters are presented by employing two ionic liquids, namely, ([C1Cnim+][Tf2N], n [...] Read more.
The study of the liquid–liquid extraction of gadolinium (Gd(III) ion) with a chelating compound, 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP), and the determination of the process parameters are presented by employing two ionic liquids, namely, ([C1Cnim+][Tf2N], n = 4, 10) and CHCl3, as diluents. Compared to CHCl3, the ionic liquid offers increased distribution ratios in an aqueous medium. A step forward, enhanced solvent extraction, and improved separation upon the addition of ethylene glycol are demonstrated, i.e., a boost of two immiscible organic phases, compared to traditional aqueous solutions. However, this is noticeable when using CHCl3, but unfortunately not with ionic liquid combination, [C1C10im+][Tf2N]. Several conclusions are given, highlighting the role of the ionic diluent in complexation processes and selectivity with an employment of the chelating agent HP for various metal s-, p-, d-, and f-cations, i.e., nearly 25 metals. A detailed evaluation of the selectivity between these metals was made when changing both the aqueous phase completely with ethylene glycol or partially with glycerol (1:1). Electron paramagnetic resonance (EPR) spectroscopy has been used to study the established chemical species in the obtained organic extracts, such as Gd3+, Fe3+, Cu2+, and Cr3+, with unpaired electrons. Full article
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