Rehydration Driven Na-Activation of Bentonite-Evolution of the Clay Structure and Composition

A new method of Na-activation of raw bentonite, rich in Ca-montmorillonite, consisting of combined thermal treatment at 200 °C, followed by immediate impregnation with aqueous solution of Na CO of concentration corresponding to 0.5, 1.0, 1.5, or 2.0 cation exchange capacity (CEC) of clay, was invest...

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Bibliographic Details
Published in:Materials 2021-12, Vol.14 (24), p.7622
Main Authors: Bahranowski, Krzysztof, Klimek, Agnieszka, Gaweł, Adam, Serwicka, Ewa M
Format: Article
Language:English
Subjects:
Activated clay
Aqueous solutions
Bentonite
Calcite
Calcium carbonate
Cation exchanging
Clay
Evolution
Fourier transforms
Heat treatment
Infrared analysis
Infrared spectroscopy
Manufacturing
Montmorillonite
Slaked lime
Sodium
Sodium carbonate
X-ray diffraction
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Summary:A new method of Na-activation of raw bentonite, rich in Ca-montmorillonite, consisting of combined thermal treatment at 200 °C, followed by immediate impregnation with aqueous solution of Na CO of concentration corresponding to 0.5, 1.0, 1.5, or 2.0 cation exchange capacity (CEC) of clay, was investigated. Structural and compositional evolution of the activated solids after 1, 2, 3, and 4 weeks of storage was monitored by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). XRD analysis indicated that within the investigated period of ageing transformation to Na-rich montmorillonite required Na CO concentration of at least 1.0 CEC. FTIR spectra showed that, depending on the Na CO concentration and ageing time, formation of Na-rich montmorillonite was accompanied by precipitation of poorly crystalline calcite, amorphous calcium carbonate, gaylussite (a double calcium-sodium carbonate), and portlandite (Ca(OH) ).
ISSN:1996-1944
1996-1944
DOI:10.3390/ma14247622