Influence of pH on the Hydrothermal Synthesis of Al-Substituted Smectites (Saponite, Beidellite, and Nontronite)
2023
Criouet, I. | Viennet, Jean-Christophe | Baron, Fabien | Balan, E. | Buch, A. | Delbes, L. | Guillaumet, M. | Remusat, L. | Bernard, Sylvain | Research On Carbon-rich Key Samples [IMPMC] (IMPMC_ROCKS) ; Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC) ; Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) | Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC) ; Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) | Unité Matériaux et Transformations - UMR 8207 (UMET) ; Centrale Lille-Institut de Chimie - CNRS Chimie (INC-CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Institut de chimie des milieux et matériaux de Poitiers [UMR 7285] (IC2MP [Poitiers]) ; Université de Poitiers = University of Poitiers (UP)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS) | Minéralogie Environnementale [IMPMC] (IMPMC_MINENV) ; Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC) ; Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) | Laboratoire de Génie des Procédés et Matériaux (LGPM) ; CentraleSupélec-Université Paris-Saclay
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显示更多 [+] 显示较少 [-]英语. Smectitic clay minerals are unique indicators of paleoenvironmental conditions and exhibit a unique reactivity in the mineral world. Smectites may exhibit tetrahedral substitutions (Al 3+-and sometimes Fe 3+-can substitute for Si 4+ 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 XRD and FTIR methods. The results of a series of syntheses conducted at various pH 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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