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Determining Surface Areas and Pore Volumes of Metal-Organic Frameworks
Published on: March 8, 2024
N(2)-BET specific surface area of bentonites
S Kaufhold1, R Dohrmann, M Klinkenberg
1BGR Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, D-30655 Hannover, Germany. s.kaufhold@bgr.de
Journal of Colloid and Interface Science
|June 24, 2010
Summary
Calcium/magnesium bentonites exhibit higher specific surface areas (SSA(N2BET)) than sodium bentonites, likely due to increased interlayer spacing from divalent cations. This finding is crucial for understanding bentonite properties.
Area of Science:
- Clay Science
- Materials Science
- Geochemistry
Background:
- Specific surface area (SSA(N2BET)) is a key property of bentonites.
- Previous studies noted variations in SSA(N2BET) but lacked clear explanations.
- Cation exchange and layer charge influence bentonite structure and properties.
Purpose of the Study:
- To investigate the factors controlling the specific surface area (SSA(N2BET)) of bentonites.
- To determine the relationship between cation type, layer charge density, and SSA(N2BET).
- To elucidate the role of interlayer spacing and microstructure in bentonite SSA(N2BET).
Main Methods:
- Analysis of 36 bentonite samples with varying cation exchange (Na+, Ca2+, Mg2+).
- Measurement of specific surface areas using N2 BET (Brunauer-Emmett-Teller) method.
- Investigation using Cu-triene-exchanged smectites to probe layer charge effects.
Main Results:
- Ca(2+)/Mg(2+) bentonites showed higher SSA(N2BET) than Na(+) bentonites.
- Low-charged smectites exhibited greater SSA(N2BET) increase compared to high-charged smectites.
- Bentonite SSA(N2BET) is primarily determined by microporosity and accessible interlayer areas.
Conclusions:
- The larger SSA(N2BET) in Ca/Mg bentonites is attributed to greater space between charges due to divalent cations.
- Microporosity and interlayer accessibility are dominant factors controlling bentonite SSA(N2BET).
- Layer number per stack and microstructure play a secondary role in SSA(N2BET).
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