Literatur vom gleichen Autor/der gleichen Autor*in
plus bei Google Scholar

Bibliografische Daten exportieren
 

Smectite fluorination and its impact on interlayer water content and structure : A way to fine tune the hydrophilicity of clay surfaces?

Titelangaben

Dazas, Baptiste ; Lanson, Bruno ; Breu, Josef ; Robert, Jean-Louis ; Pelletier, Manuel ; Ferrage, Eric:
Smectite fluorination and its impact on interlayer water content and structure : A way to fine tune the hydrophilicity of clay surfaces?
In: Microporous and Mesoporous Materials. Bd. 181 (15 November 2013) . - S. 233-247.
ISSN 1873-3093
DOI: https://doi.org/10.1016/j.micromeso.2013.07.032

Abstract

In addition to isomorphic cation substitutions, smectite layers may present anionic substitutions with fluorine replacing the structural hydroxyl groups and inducing a reduced number of H2O molecules hydrating interlayer cations. The resulting additional versatility of smectite layers could be used to fine-tune the hydrophilicity of pure or intercalated smectite pending a detailed understanding of interlayer water organization. The present article thus reports on the hydration of (fluoro-)hectorite samples exhibiting similar charge density (structural formulae: [Na0.8·nH2O]inter[Mg5.2Li0.8]oct[Si8.0]tetO20(OH,F)4). Water sorption isotherms and PIGE/PIXE analyses allowed constraining the water content over the probed range of relative humidity and the bulk chemistry, respectively. Modeling of X-ray diffraction (XRD) profiles obtained along water vapor desorption isotherms allowed gaining additional insights in the distribution of interlayer H2O molecules. Compared to hydroxylated smectites of similar charge, fluorinated hectorites contain ∼30% less interlayer H2O molecules although transitions between discrete hydration states are observed for similar values of relative humidity. These molecules (3–4 and 6–8 H2O molecules per cation in the mono- and bi-hydrated states, respectively) predominantly belong to the hydration sphere of interlayer cations, although additional H2O molecules are present in the bi-hydrated state. As a consequence, the positional disorder of interlayer H2O molecules is much reduced in fluorinated samples, thus increasing the minimum distance from an interlayer H2O molecule to the smectite layer, most likely owing to the hydrophobicity of fluorinated layers. Finally, the distribution of layers with a given hydration state is more heterogeneous within smectite crystals for fluorinated smectites, compared to hydroxylated ones, possibly as the result of the improved crystallinity.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Keywords: Smectite; Hydrophilicity; Hydrophobicity; Interlayer structure; Anionic substitutions; Smectite-based nanocomposites; Clay heterostructures
Institutionen der Universität: Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Lehrstuhl Anorganische Chemie I > Lehrstuhl Anorganische Chemie I - Univ.-Prof. Dr. Josef Breu
Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Lehrstuhl Anorganische Chemie I
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
Eingestellt am: 21 Mär 2018 08:17
Letzte Änderung: 04 Okt 2019 09:05
URI: https://eref.uni-bayreuth.de/id/eprint/9357