Speciation and Characterization of Transition Metals and Rare Earth Elements

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: closed (31 October 2020) | Viewed by 14628

Special Issue Editors

Department of Earth and Geo-environmental Sciences, University of Bari “Aldo Moro”, 70121 Bari, Italy
Interests: mineralogy; crystallography; X-ray diffraction; X-ray photoelctron spectroscopy; phyllosilicates; mixed-framework microporous minerals
Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, 20133 Milano, Italy
Interests: fuel cells; materials characterization; alternative energy; impedance spectroscopy; water treatment
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Special Issue Information

Dear Colleagues,

This special issue addresses research topics dealing with the speciation and characterization of transition metals and rare earth elements in minerals, rocks, or sediments.

Transition metals are very important in many geochemical processes. Many factors affect their reactivity in the environment, for instance their oxidation state reflects the redox condition of the environment. In addition, the transition metals can play a key role into the crystal-chemistry of the minerals. Therefore, the characterization of the transition metals can provide valuable information about the petrogenetic conditions of the host rocks, while the understanding of their mineralogical and crystal-chemical aspects can suggest paths to the synthesis of innovative materials.

Rare earth elements (REEs) are another critical issue. In geology, REEs can be used as natural tracers of specific geological processes or as indicators of geochemical signatures. In materials science, they are used in many electronical devices or for the production of catalysts, phosphors, and polishing compounds. For these reasons, all of these elements are expected to experience rising demand.

The special issue is intended to be an international venue for mineralogists, geologists, and geochemists to publish new research with a focus on transition metals and REEs and on promising techniques for their full characterization in geological materials.

Dr. Ernesto Mesto
Dr. Saverio Latorrata
Guest Editors

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Keywords

  • Transition metals
  • Rare earth elements
  • Speciation
  • Crystallography
  • Geochemical characterization

Published Papers (5 papers)

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Research

18 pages, 4741 KiB  
Article
Innovative Magnetic Aggregates for the Removal of Transition Metals from Industrial Wastewater
Minerals 2021, 11(6), 643; https://doi.org/10.3390/min11060643 - 17 Jun 2021
Cited by 1 | Viewed by 2566
Abstract
A novel adsorbent material based on microaggregates of Fe3O4 magnetic nanoparticles functionalized with succinic acid has been developed. The magnetic aggregates (MA) were characterized in terms of the size distribution (master sizer analysis), morphology (TEM), chemical structure (IR-spectroscopy and XRD), magnetic properties (VSM), [...] Read more.
A novel adsorbent material based on microaggregates of Fe3O4 magnetic nanoparticles functionalized with succinic acid has been developed. The magnetic aggregates (MA) were characterized in terms of the size distribution (master sizer analysis), morphology (TEM), chemical structure (IR-spectroscopy and XRD), magnetic properties (VSM), and Z-Potential. The effects of various parameters such as contact time, dosage of magnetic aggregates, the amount of succinic acid on the magnetic aggregates on the adsorption capacity, as well as the efficiency of the treatment in the adsorption of two transition metals, copper (Cu) and zinc (Zn) from real wastewater, were investigated. The kinetic behavior was analyzed by using the Lagergren pseudo-first-order, pseudo-second-order, and Elovich and intra-particle diffusion models. Langmuir and Freundlich’s models were applied to simulate the adsorption equilibrium. The magnetic aggregates reached the equilibrium condition relatively fast, within 10 min. Magnetic aggregates with a higher amount of succinic acid in their formulation showed a higher adsorption capacity of the two metals in all the experiments. This is consistent with the adsorption mechanism mainly based on electrostatic interaction between the metal ions and the negative charges on the surface of magnetic aggregates. A higher adsorption capacity for the removal of copper compared to zinc was found. Additionally, the electrochemical characterization of the magnetic aggregates was done as a preliminary study for proposing a regeneration method of the MA along with the extraction metals adsorbed based on an electrochemical process. Full article
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15 pages, 2633 KiB  
Article
Rare Earths (La, Y, and Nd) Adsorption Behaviour towards Mineral Clays and Organoclays: Monoionic and Trionic Solutions
Minerals 2021, 11(1), 30; https://doi.org/10.3390/min11010030 - 29 Dec 2020
Cited by 14 | Viewed by 2100
Abstract
Metals from electric and electronic waste equipment (WEEE) can be recovered by dissolution with acids followed by liquid–liquid extraction. A possible alternative to liquid–liquid extraction is liquid–solid adsorption, where sorbents efficiency is the key factor for process efficiency. In this respect, aim of [...] Read more.
Metals from electric and electronic waste equipment (WEEE) can be recovered by dissolution with acids followed by liquid–liquid extraction. A possible alternative to liquid–liquid extraction is liquid–solid adsorption, where sorbents efficiency is the key factor for process efficiency. In this respect, aim of this paper is the study of the behaviour of two solid sorbents for the recovery of Rare Earths (REs)—in particular, La, Nd, and Y—from scraps of end-of-Life (EOL) electronic equipment. Two solid matrices were considered: a pristine montmorillonite clay and a modified-montmorillonite clay intercalated with a commercial pentaethylen-hexamine. The capture ability of the solids was tested towards single-ion La, Nd, and Y solutions and a multi-element solution containing the three ions. Before and after the uptake step, samples of both the solid and liquid phases were analysed. For both sorbents, at lower metal initial concentrations, the ions were captured in similar amount. At higher concentrations, pure clay showed a high total uptake towards La ions, likely due to surface interactions with clay sites. The organoclay preferentially interacts with Nd and Y. Considering the presence of the polyamine, this behaviour was related to ion coordination with the amino groups. The capture behaviour of the two sorbents was related to the different physicochemical properties of the ions, as well as to the ionic radius. Full article
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16 pages, 2949 KiB  
Article
Reduced Graphene Oxide Membranes as Potential Self-Assembling Filter for Wastewater Treatment
Minerals 2021, 11(1), 15; https://doi.org/10.3390/min11010015 - 25 Dec 2020
Cited by 8 | Viewed by 3246
Abstract
This work focuses on the investigation of the capability of reduced graphene oxide (rGO) filters to remove metals from various wastewater. The process to produce rGO membranes is reported and discussed, as well as their ability to capture ions in complex solutions, such [...] Read more.
This work focuses on the investigation of the capability of reduced graphene oxide (rGO) filters to remove metals from various wastewater. The process to produce rGO membranes is reported and discussed, as well as their ability to capture ions in complex solutions, such as tap or industrial wastewater. Multi-ion solutions, containing Cu2+, Fe3+, Ni2+, and Mn2+ to simulate mine wastewater, or Ca2+ and Mg2+ to mimic drinkable water, were used as models. In mono-ionic solutions, the best capture efficiency values were proved for Ca2+, Fe3+, and Ni2+ ions, while a matrix effect was found for multi-ion solutions. However, interesting capture efficiencies were measured in the range of 30–90%, depending on the specific ion, for both single and multi-ion solutions. An attempt is proposed to correlate ions capture efficiency with ions characteristics, such as ionic radius or charge. Combining a satisfactory capture efficiency with low costs and ease of treatment unit operations, the approach here proposed is considered promising to replace other more complex and expensive filtration techniques. Full article
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16 pages, 6878 KiB  
Article
Zircon LA-ICP-MS U-Pb Ages and the Hf Isotopic Composition of the Ore-Bearing Porphyry from the Yanghuidongzi Copper Deposit, Heilongjiang, China, and Its Geological Significance
Minerals 2019, 9(11), 676; https://doi.org/10.3390/min9110676 - 02 Nov 2019
Cited by 2 | Viewed by 2444
Abstract
The Yanghuidongzi copper deposit is a typical porphyry copper deposit located at the eastern margin of the Xing’anling-Mongolian Orogenic Belt (XMOB). While much attention have been paid to the ore-forming age of the deposit and the magma source of the ore-bearing porphyry, this [...] Read more.
The Yanghuidongzi copper deposit is a typical porphyry copper deposit located at the eastern margin of the Xing’anling-Mongolian Orogenic Belt (XMOB). While much attention have been paid to the ore-forming age of the deposit and the magma source of the ore-bearing porphyry, this paper approaches this issue with the methods of the LA-ICP-MS zircon U-Pb dating and Lu-Hf isotopic composition of the Yanghuidongzi porphyry copper deposit. The results reveal that the Yanghuidongzi porphyry copper deposit was formed in the Early Jurassic (189.6 ± 1.0 Ma), which corresponds to the time of magmatic activity in this region. The background studies of ore-forming dynamics indicate that the formation of the Yanghuidongzi copper deposit is related to the subduction of the Paleo-Pacific plate. The Yanghuidongzi ore-bearing porphyry zircons have a positive εHf(t) value (4.4–7.0), a high 176Hf/177Hf ratio (0.282786–0.282854), and a two-stage Hf model ages (TDM2) ranging from 783 Ma to 943 Ma, all of which suggest that the Early Jurassic granodiorite porphyry of the Yanghuidongzi deposit was formed by the partial melting of newly grown crustal material from the depleted mantle in the Neoproterozoic. Full article
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14 pages, 3243 KiB  
Article
A Theoretical Study on the Electronic Structure and Floatability of Rare Earth Elements (La, Ce, Nd and Y) Bearing Fluorapatite
Minerals 2019, 9(8), 500; https://doi.org/10.3390/min9080500 - 20 Aug 2019
Cited by 16 | Viewed by 3536
Abstract
Calcium atoms are often replaced by rare earth elements (REEs) in the lattice of fluorapatite (Ca10F2(PO4)6), making the phosphate ore an important potential rare earth resource. In this paper, the electronic properties of REEs (La, [...] Read more.
Calcium atoms are often replaced by rare earth elements (REEs) in the lattice of fluorapatite (Ca10F2(PO4)6), making the phosphate ore an important potential rare earth resource. In this paper, the electronic properties of REEs (La, Ce, Nd and Y) bearing fluorapatite crystals have been investigated by density functional theory. Results of calculation indicated that the existence of REEs increased the cell parameters of fluorapatite in varying degrees. The REEs substitution made the Fermi level of fluorapatite to move to higher energy levels, making it easier to accept electrons. Except for Y, all the other REEs (La, Ce and Nd) showed that the electronic state mainly exists in the valence band. The Fermi level of REEs were mainly contributed by La5d, Ce4f, Nd4f and Y4d, respectively. The Mulliken values of REE–F and REE–O bonds in REEs-bearing fluorapatites were larger than those of Ca–F and Ca–O bonds in the perfect crystal, and the values of Y–F and Y–O bonds were the largest. The results of interaction between fluorapatite and oleic acid by frontier molecular orbital analysis suggested that the substitution of REEs can improve the reactivity of fluorapatite with oleic acid. Full article
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