Details
| Original language | English |
|---|---|
| Pages (from-to) | 249-266 |
| Number of pages | 18 |
| Journal | Clay minerals |
| Volume | 44 |
| Issue number | 2 |
| Publication status | Published - 1 Jun 2009 |
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 (Deff) 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 Deff 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 Deff 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%, Deff for all samples is one order of magnitude less than in the saturated state. Results on Deff obtained by ATR-FTIR spectroscopy are in good agreement with through-diffusion studies.
Keywords
- Diffusion coefficient, HO-DO exchange, HDPy-montmorillonite, IR spectroscopy, Microstructure, Surface charge, Wettability
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Clay minerals, Vol. 44, No. 2, 01.06.2009, p. 249-266.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Determination of diffusive transport in HDPy-montmorillonite by H 2O-D2O exchange using in situ ATR-FTIR spectroscopy
AU - Schampera, B.
AU - Dultz, S.
N1 - Copyright: Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2009/6/1
Y1 - 2009/6/1
N2 - 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 (Deff) 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 Deff 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 Deff 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%, Deff for all samples is one order of magnitude less than in the saturated state. Results on Deff obtained by ATR-FTIR spectroscopy are in good agreement with through-diffusion studies.
AB - 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 (Deff) 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 Deff 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 Deff 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%, Deff for all samples is one order of magnitude less than in the saturated state. Results on Deff obtained by ATR-FTIR spectroscopy are in good agreement with through-diffusion studies.
KW - Diffusion coefficient
KW - HO-DO exchange
KW - HDPy-montmorillonite
KW - IR spectroscopy
KW - Microstructure
KW - Surface charge
KW - Wettability
UR - http://www.scopus.com/inward/record.url?scp=70349742551&partnerID=8YFLogxK
U2 - 10.1180/claymin.2009.044.2.249
DO - 10.1180/claymin.2009.044.2.249
M3 - Article
AN - SCOPUS:70349742551
VL - 44
SP - 249
EP - 266
JO - Clay minerals
JF - Clay minerals
SN - 0009-8558
IS - 2
ER -