An insight into the surface properties of calcined kaolinitic clays: The grinding effect

•Surface Lewis basic properties increase from kaoline to metakaolinitic materials.•The extensive grinding of metakaolinitic materials affords a decrease of the γsd.•Lewis basic properties of the metakaolines surface also increase with grinding.•Grinding results are largely explained by changes in th...

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Bibliographic Details
Published in:Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2014-08, Vol.455, p.49-57
Main Authors: Gamelas, J.A.F., Ferraz, E., Rocha, F.
Format: Article
Language:English
Subjects:
Adsorption
Atomic structure
Calcined kaolins
Clays
Grinding
Hydroxyl groups
IGC
Metakaolins
Nanostructure
Surface chemistry
Surface energy
Surface properties
Trichloromethane
XPS
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Summary:•Surface Lewis basic properties increase from kaoline to metakaolinitic materials.•The extensive grinding of metakaolinitic materials affords a decrease of the γsd.•Lewis basic properties of the metakaolines surface also increase with grinding.•Grinding results are largely explained by changes in the surface nanoroughness.•Shown results may have interest in the composites area/cation-exchange properties. The present work aimed characterizing in a systematic way the surface of metakaolinitic materials produced by calcination of a kaolinitic clay at different temperatures and to study the effect of grinding on the surface properties of metakaolinitic materials. Using X-ray photoelectron spectroscopy, it was found for all materials a Si/Al atomic ratio close to 1, confirming the presence of the 1:1 clay structure. By inverse gas chromatography, an increase of the Lewis basic properties of the surfaces of metakaolinitic materials in comparison to the original clay was found, which was due to the condensation of hydroxyl groups in the structure of the clay. The grinding of the metakaolinitic materials afforded a decrease of the dispersive component of the surface energy (γsd) as well as an increase of the specific interaction with sterically hindered molecules, caused by the diminishing of the materials surface nanoroughness. The Lewis basic properties of the materials surface also increased with grinding. Noticeably, for all studied materials a good inverse relation could be found between the γsd and the specific interaction of trichloromethane (but not with dichloromethane), showing the importance of surface nanoroughness on the adsorption process of bulky molecules.
ISSN:0927-7757
1873-4359
DOI:10.1016/j.colsurfa.2014.04.038