Determination of diffusive transport in HDPy-montmorillonite by H ₂O-D₂O exchange using in situ ATR-FTIR spectroscopy

verfasst von

B. Schampera, S. Dultz

Abstract

The anion adsorption capability of clays can be improved significantly by modification with certain organic cations. However, surface properties and the microstructure of the clay might change and limit the use of organo-clays in barrier systems. In this study an experimental setup is introduced which allows the rapid determination of effective diffusion coefficients (D_eff) for H₂O in clay samples. H₂O→D₂O exchange experiments on hexadecylpyridinium (HDPy)-montmorillonite samples were performed in a diffusion cell attached to the ATR unit of a Fourier-transform infrared spectrometer. The mean D_eff for H₂O in a D ₂O-saturated original montmorillonite is 2.44×10^-11 m²/s in the bulk density range of 1.1-1.8 g/cm³. Hydrophobic surfaces increase the diffusivity only at high bulk densities in the saturated state. The mean D_eff is lower when HDPy is applied in amounts ≥80% of the cation exchange capacity in comparison with the original sample. At a saturation degree of the pores of 40%, D_eff for all samples is one order of magnitude less than in the saturated state. Results on D_eff obtained by ATR-FTIR spectroscopy are in good agreement with through-diffusion studies.

Organisationseinheit(en)

Institut für Bodenkunde
AG Bodenchemie

Typ

Artikel

Journal

Clay minerals

Band

44

Seiten

249-266

Anzahl der Seiten

18

ISSN

0009-8558

Publikationsdatum

01.06.2009

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Geochemie und Petrologie

Elektronische Version(en)

https://doi.org/10.1180/claymin.2009.044.2.249 (Zugang: Unbekannt)