Characterization of Iron-Rich Phyllosilicates Formed at Different Fe/Si Ratios

Dzene, Līva; Dutournié, Patrick; Brendlé, Jocelyne; Limousy, Lionel; Meins, Jean‐Marc Le; Michelin, Laure; Vidal, Loı̈c; Gree, Simon; Abdelmoula, Mustapha; Martin, Christelle; Michau, Nicolas

doi:10.1007/s42860-022-00204-6

Cited by 4 publications

(3 citation statements)

References 67 publications

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“…The synthesis of [4] Al-nontronite is also very sensitive to the pH of solutions, as is the case for [4] Fenontronite as acknowledged earlier (Andrieux & Petit, 2010;Boumaiza et al, 2020;Dzene et al, 2022). Only the gel produced using an AlCl 3 solution at pH 10.6 and immersed in a solution at pH 12.5 leads to pure [4] Al-nontronite.…”

Section: Influence Of Phmentioning

confidence: 85%

“…pure water in equilibrium with atmospheric CO 2 ) or into 16.5 mL of a solution composed of pure water in which was added NaOH to reach a pH of 12, 12.5, or 13, while the two gels produced using either the AlCl 3 solution at pH 5.3 or the AlCl 3 solution at pH 8 were immersed only into 16.5 mL of a solution composed of pure water in which was added NaOH to reach a pH of 12.5 (cf Table 2). All reactors were then put in an oven at 150°C (4.75 bar) for 2.5 days, following the recommendations of Andrieux & Petit (2010), Baron et al (2016a), and Dzene et al (2022). In fact, higher temperatures (>200°C) may favor the formation of kaolinite, hematite (akaganeite), or aegirine (Delvaux et al, 1989;Decarreau et al, 2008;Andrieux & Petit, 2010)…”

Section: Nontronite Synthesesmentioning

confidence: 99%

“…-OH at ~3560 cm -1 , δFe 2 3+ -OH at 815 cm -1 , the 855 cm -1 (not assigned), [4] Fe-O at 707 cm -1 , and [6] Fe 3+ -O ap ~667 cm -1 ; Goodman et al, 1976;Baron et al, 2016a;Dzene et al, 2022) were stronger in the FTIR spectrum of the solid produced in the solution at pH 13 than in the FTIR spectrum of the solid produced in the solution at pH 12.5, indicating that the nontronite produced at pH 12.5 was poorly crystallized. No band typical of nontronite was observed in the FTIR spectra of the solids produced in solutions at pH lower than 12.5 (Fig.…”

Section: +mentioning

confidence: 99%

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Influence of pH on the Hydrothermal Synthesis of Al-Substituted Smectites (Saponite, Beidellite, and Nontronite)

Criouet,

Viennet,

Baron

et al. 2023

Clays and clay miner.

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Smectitic clay minerals are unique indicators of paleoenvironmental conditions and exhibit a unique reactivity in the mineral world. Smectites may exhibit tetrahedral substitutions (Al3+, and sometimes Fe3+, can substitute for Si4+ in tetrahedral sites), resulting in a layer-charge increase, thereby impacting their properties (e.g. swelling and sorption capacities, catalytic properties, expandable abilities). The objective of the present study was to determine the influence of pH conditions on the hydrothermal production of smectite end-members exhibiting tetrahedral Al substitutions (saponite, beidellite, and nontronite), using X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) methods. The results of a series of syntheses conducted at various pH values allowed discussion of the crystallization pathways of these smectites from a mechanistic point of view. Altogether, the present study provided easily reproducible protocols for the hydrothermal production of pure saponite, nontronite, or beidellite (i.e. with no other mineral). The successful synthesis of pure saponite was achieved by exposing the starting gels to 230°C for 4 days in solutions at pH ranging from 5.5 to 14. The successful synthesis of pure beidellite was achieved by exposing the starting gels to 230°C for 9 days in a solution at pH 12. The successful synthesis of pure nontronite was achieved by exposing the starting gels to 150°C for 2.5 days in a solution at pH 12.5. Although extrapolating experimental results to natural settings remains difficult, the results of the present study may be of great help to constrain better the geochemical conditions existing or having existed on extraterrestrial planetary bodies.

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Section: Influence Of Phmentioning

confidence: 85%

Section: Nontronite Synthesesmentioning

confidence: 99%

Section: +mentioning

confidence: 99%

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Influence of pH on the Hydrothermal Synthesis of Al-Substituted Smectites (Saponite, Beidellite, and Nontronite)

Criouet,

Viennet,

Baron

et al. 2023

Clays and clay miner.

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The iron oxidation state of Ryugu samples

Roskosz,

Beck,

Viennet

et al. 2023

Meteorit & Planetary Scien

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The Hayabusa2 mission sampled Ryugu, an asteroid that did not suffer extensive thermal metamorphism, and returned rocks to the Earth with no significant air exposure. It therefore offers a unique opportunity to study the redox state of carbonaceous Cb‐type asteroids and evaluate the overall redox state of the most primitive rocks of the solar system. An analytical framework was developed to investigate the iron mineralogy and valence state in extraterrestrial material at the micron scale by combining x‐ray diffraction, conventional Mössbauer (MS), and nuclear forward scattering (NFS) spectroscopies. An array of standard minerals was analyzed and cross‐calibrated between MS and NFS. Then, MS and NFS spectra on three Ryugu grains were collected at the bulk and the micron scales. In Ryugu samples, iron is essentially accommodated in magnetite, clay minerals (serpentine–smectite), and sulfides. Only a single set of Mössbauer parameters was necessary to account for the entire variability observed in MS and NFS spectra, at all spatial scales investigated. These parameters therefore make up a fully consistent iron mineralogical model for the Ryugu samples. As far as MS and NFS spectroscopies are concerned, Ryugu grains are overall similar to each other and share most of their mineralogical features with CI‐type chondrites. In detail however, no ferrihydrite is found in Ryugu particles even at the very sensitive scale of Mössbauer spectroscopy. The typical Fe3+/Fetot of clay minerals is much lower than typical redox ratios measured in CI chondrites (Fe3+/Fetot = 85%–90%). Furthermore, magnetite from Ryugu is stoichiometric with no significant maghemite component, whereas up to 12% of maghemite was previously identified in the Orgueil's so‐called magnetite. These differences suggest that most CI meteorites suffered terrestrial alteration and that the preterrestrial composition of these carbon‐rich samples was less oxidized than previously measured. However, it is not clear yet whether or not the parent bodies of CI chondrites were as reduced as Ryugu. Finally, the high spatial resolution of NFS allows to disentangle the redox state and the crystal chemistry of iron accommodated in serpentine and smectite. The most likely polytype of serpentine is lizardite, containing <35% of Fe3+, a fraction of which being tetrahedrally coordinated. Smectite is more oxidized (Fe3+/Fetot > 65%) and mainly contains octahedral ferric iron. This finding implies that these clays formed from highly alkaline fluids and the spatial variability highlighted here may suggest a temporal evolution or a spatial variability of the nature of this fluid.

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Interfacial interactions controlling adsorption of metal cations on montmorillonite

Li,

Kurniawan,

Christidis

et al. 2024

American Mineralogist

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Montmorillonite (Mt) is a ubiquitous swelling clay mineral and major component of soft rocks, sediments, and soils with an inherent capability to sorb metal cations. This unique feature renders Mt important for the enrichment and mobilization of environmentally important metal cations, retardation of heavy metals and radionuclide ions, the evolution of clay mineral itself, soils and sediments, and other geological processes. Understanding the interfacial interactions of Mt with metal cations at the molecular level is of fundamental importance in all these processes, but still remains elusive, due to the chemical and structural complexity of Mt surfaces and the diverse chemistries of metal cations. In this Review, we aim to provide the reader with a comprehensive overview of the adsorption modes of metal cations on basal and edge surfaces of Mt, local chemical environments of the cation binding sites, the driving forces for metal sorption, and factors influencing the dynamics of cation uptake onto Mt surfaces. Various surface complexation models [i.e., nonelectrostatic model (NEM), constant capacitance model (CCM), diffuse layer model (DLM), and triple-layer model (TLM)], advanced spectroscopic techniques (i.e., NEM, CCM, DLM, and TLM), and atomistic simulation methods (i.e., MD, DFT, and FPMD) have been used in conjunction with macroscopic adsorption experiments to gain detailed insights into the interfacial interactions of metal cations on Mt. Mt adsorbs metal cations via three independent pathways: (1) cation exchange; (2) surface complexation; and (3) nucleation and surface precipitation. The principal driving force for cation exchange is electrostatic interaction, while chemical bonding governs the two other mechanisms that depend on the basal and edge surface properties of Mt. The siloxane cavities on the tetrahedral basal plane exhibit the strongest adsorption sites for cation exchange and are greatly affected by the the degree of Al3+/Si4+ tetrahedral substitutions. At the amphoteric edge surfaces bearing hydroxyl groups, metal cations could form mono/multiden-tate surface complexes on Mt [010] and [110] edges. Ionic strength, pH, the presence of competing cations, temperature, and layer charge have been shown to affect the adsorption mechanisms and quantity of adsorbed cations. The updated information on the interfacial interactions of metal cations with Mt basal and edge surfaces presented in this review provides an improved understanding of the enrichment of metals, formation of metal ores, and natural biogeochemical cycles, as well as may promote technological and engineering applications of this important clay mineral in environmental remediation, geological repository, petroleum exploration and extraction, and extraterrestrial research.

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Characterization of Iron-Rich Phyllosilicates Formed at Different Fe/Si Ratios

Cited by 4 publications

References 67 publications

Influence of pH on the Hydrothermal Synthesis of Al-Substituted Smectites (Saponite, Beidellite, and Nontronite)

Influence of pH on the Hydrothermal Synthesis of Al-Substituted Smectites (Saponite, Beidellite, and Nontronite)

The iron oxidation state of Ryugu samples

Interfacial interactions controlling adsorption of metal cations on montmorillonite

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