Sulphidation of valleriite in SO2 solutions

Laptev, Yu. V.; Шевченко, В. С.; Уракаев, Ф. Х.

doi:10.1016/j.hydromet.2009.04.018

Cited by 17 publications

(20 citation statements)

References 10 publications

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“…For this study, natural sulfide minerals from Noril'sk are studied, i.e., pyrrhotite, [Fe 9 S 10 ], containing impurities of pentlandite, [(Ni,Fe) 9 2 ]] from the Nadezhda deposit (Noril'sk provenance) contained about 50% of the target mineral and varying minor quantities of pyrrhotite, chalcopyrite, magnetite, serpentine, pyrite; in more detail this material was characterized in refs. [39,[44][45][46][47][48][49][50]. Plates with the size of approximately 2 × 4 × 5 mm were cut from the minerals, and the surface was polished with sandpaper, washed with distilled water and wiped with wet filter paper to remove fine particles directly before Pt deposition.…”

Section: Methodsmentioning

confidence: 99%

X-ray Photoelectron Spectroscopy (XPS) Study of the Products Formed on Sulfide Minerals Upon the Interaction with Aqueous Platinum (IV) Chloride Complexes

2018

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The interaction of aqueous solutions bearing platinum-group elements (PGEs) with sulfides is important for understanding the formation and weathering of PGE ore deposits, mineral processing, and synthesis of nanomaterials. Here, the surface species formed upon the contact of the main sulfide minerals (pyrite, pyrrhotite, galena, chalcopyrite and valleriite) with the solutions of H 2 PtCl 6 (pH 1.5, 20 • C) have been studied using X-ray photoelectron spectroscopy (XPS). Uptake of Pt increased gradually with increasing interaction time, and depended, as well as the composition of immobilized products, on the mineral nature and the state of its surface, e.g., the chemical pre-treatment. The highest rate of Pt deposition was observed on galena and valleriite and the lowest on pyrite and pyrrhotite. The preliminary moderate oxidation of pyrrhotite promoted Pt deposition, which, however, was hindered under harsh reaction conditions. The pre-oxidation of pyrite in all cases resulted in a decrease of the Pt deposition. Initially, Pt(IV) chloride complexes adsorb onto the mineral surface, and then the reduction of Pt(IV) to Pt(II) and substitution of chloride ions with sulfide groups occur forming sulfides of Pt(II) and then, Pt(IV). The reduction of Pt species to the metallic state was observed at valleriite after 24 h, probably due the negative charge of the sulfide nanolayers of this sulfide-hydroxide composite mineral.

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Section: Methodsmentioning

confidence: 99%

X-ray Photoelectron Spectroscopy (XPS) Study of the Products Formed on Sulfide Minerals Upon the Interaction with Aqueous Platinum (IV) Chloride Complexes

2018

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“…1). The natural prototype of this material is mineral valleriite [20][21][22][23][24][25][26][27][28][29][30] that remains poorly explored and uninvolved in commercial processing [28,29]. The minerals usually contain Al and Fe cations replacing Mg in the brucite-like sheets; for instance, Hughes et al [30] have reported the composition of valleriites ranged from [CuFeS2]1.67[Mg0.70Al0.30(OH)2] to [Cu1.30Fe0.70S2]1.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

Mikhlin¹,

Борисов

Vorobyev³

et al. 2022

Preprint

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We introduce here a multifunctional material composed of alternating atomic sulfide sheets close to CuFeS2 and Mg-based hydroxide ones (valleriite), which are assembled due to their electric charges of opposite sign. Valleriite particles of 50-200 nm in the lateral size and 10-20 nm thick were synthesized via a simple hydrothermal pathway using various concentrations of precursors and dopants, and examined with XRD, TEM, EDS, X-ray photoelectron spectroscopy, reflection electron energy loss spectroscopy (REELS), Mössbauer, Raman and UV-vis-NIR spectroscopies, magnetic, dynamic light scattering, zeta potential measurements. The electronic, magnetic and optical characteristics are found to be critically dependent of the charge (electron density) at the narrow-gap sulfide layers containing Cu+ and Fe3+ cations, and can be tuned via the composition of hydroxide part. Particularly, substitution of Mg2+ with Al3+ increases the negative charge of the hydroxide layers and reduces the content of Fe3+-OH centers (10-45% of total iron); the effects of Cr and Co dopants entering both layers are more complicated. Mössbauer doublets of paramagnetic Fe3+ detected at room temperature transform to several Zeeman sextets at 4.2 K; the hyperfine fields up to 500 kOe and complex magnetic behavior, but not pure paramagnetism or antiferromagnetism, were observed for valleriites with the higher positive charge of the sulfide sheets, probably due to the depopulation of the minority-spin 3d states of S-bonded Fe3+ ions. Aqueous colloids of valleriite show optical absorption at 500 - 750 nm, which, along with the peaks at the same energies in REELS, may arise due to quasi-static dielectric resonance involving the vacant Fe 3d band and being dependent on the composition of both layers too. These and other findings call attention to the of valleriites as a new rich family of 2D materials for a variety of potential applications.

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“…The flake-like nanoparticles composed of altering quasi-atomic Cu-Fe-S sulfide and Mg hydroxide sheets are manufactured in the environment-friendly hydrothermal process using common reagents. Such a chalcogenide-hydroxide incommensurate structures looks unusual and complex but there exist a number of natural [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and synthetic [43][44][45][46][47][48][49][50][51] layered materials, suggesting that those are quite stable and spontaneously assemble via a mechanism that needs to be understood. The composition and then morphology and properties of the materials can be engineered by varying the nature and concentrations of precursors, modifiers, dopants far beyond those used in this case study.…”

Section: Discussionmentioning

confidence: 99%

“…The natural prototype of this material is mineral valleriite [20][21][22][23][24][25][26][27][28][29][30] that remains insufficiently explored and its ores are not involved in commercial processing, despite the high content of heavy and precious metals. [28,29] The minerals usually contain Al and Fe cations partially substituting Mg in the brucite-like hydroxide layers, whereas sulfide layers are often depleted in Fe. For instance, Hughes et al [30] have reported the composition of synthetic valleriites ranged from [CuFeS2]1.67[Mg0.70Al0.30(OH)2] to [Cu1.30Fe0.70S2]1.35[Mg0.74Al0.26(OH)2].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

Mikhlin¹,

Борисов

Vorobyev³

et al. 2021

Preprint

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Two-dimensional phenomena are attracting enormous interest at present and the search for novel 2D materials is very challenging. We propose here the layered material valleriite composed of altering atomic sheets of Cu-Fe sulfide and Mg-based hydroxide synthesized via a simple hydrothermal pathway as particles of 50-200 nm in the lateral size and 10-20 nm thick. The solid products and aqueous colloids prepared with various precursor ratios were examined using XRD, TEM, EDS, X-ray photoelectron spectroscopy (XPS), reflection electron energy loss spectroscopy (REELS), Raman, Mössbauer, UV-vis-NIR spectroscopies, magnetic, dynamic light scattering, zeta potential measurements. The material properties are largely determined by the narrow-gap (less than 0.5 eV) sulfide layers containing Cu+ and Fe3+ cations, monosulfide and minor polysulfide anions but are strongly affected by the hydroxide counterparts. Particularly, Fe distribution between sulfide (55-90%) and magnesium hydroxide layers is controlled through insertion of Al into the hydroxide part and by Cr and Co dopants entering both layers. Room-temperature Mössbauer signals of paramagnetic Fe3+ transformed to several Zeeman sextets with hyperfine magnetic fields up to 500 kOe in the sulfide layers at 4 K. Paramagnetic or more complicated characters were observed for valleriites with higher and lower Fe concentrations in hydroxide sheets, respectively. Valleriite colloids showed negative zeta potentials, suggesting negative electric charging of the hydroxide sheets, and optical absorption maxima between 500 nm and 700 nm, also depended on the Fe distribution. The last features observed also in the REELS spectra may be due to localized surface plasmon or, more likely, quasi-static dielectric resonance. The tunable composition, electronic, magnetic, optic and surface properties highlight valleriites as a rich platform for novel 2D composites promising for numerous applications.

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Sulphidation of valleriite in SO2 solutions

Cited by 17 publications

References 10 publications

X-ray Photoelectron Spectroscopy (XPS) Study of the Products Formed on Sulfide Minerals Upon the Interaction with Aqueous Platinum (IV) Chloride Complexes

X-ray Photoelectron Spectroscopy (XPS) Study of the Products Formed on Sulfide Minerals Upon the Interaction with Aqueous Platinum (IV) Chloride Complexes

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

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