Repercussions of size heterogeneity on the measurement of specific surface areas of colloidal minerals: Combination of macroscopic and microscopic analyses

Abstract : The nature and the extent of reactive crystalline surfaces for colloidal particles is an essential factor for understanding of reactions at the solid-liquid interfaces. The measurement of this specifi c surface area for colloidal mineral particles is usually obtained from gas-adsorption isotherms. This measurement, based on adsorbate-adsorbent interactions, yields overall weight-averaged values that fail to display the distribution of geometrical specifi c surface areas of individual particles. The present work proposes to use three dimensional atomic force microscopy (AFM) images to characterize the distribution of geometrical features of hexagonal plate-like gibbsite [Al(OH)3] particles without microporosity. This sub-micrometer approach, which requires minute quantities of solids (picograms), demonstrates the broad distribution of specifi c surface areas (lateral, basal, and total) determined for each individual particle in our sample. The resulting weight-averaged specifi c surface area values of basal and lateral surfaces, calculated from this distribution, agree with values measured by Kr-adsorption isotherms. The lateral specifi c surface area values thus obtained confi rm the estimates given by and are correlated with the infrared spectrum analysis proposed in our previous papers. Moreover, these results reveal the importance of the smallest particles in the overall distribution, whereas the weight-averaged value is monitored by high-mass particles that are few in number. This kind of specifi c surface area heterogeneity must be taken into account in describing the reactivity of anisotropic shaped mineral particles.
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Article dans une revue
American mineralogist, 2004, 89 (10), pp.1456-1462. 〈10.2138/am-2004-1013〉
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https://hal.univ-lorraine.fr/hal-01342996
Contributeur : Marie-Camille Caumon <>
Soumis le : jeudi 7 juillet 2016 - 11:58:46
Dernière modification le : jeudi 24 mai 2018 - 10:32:01

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Marie-Camille Jodin, Fabien Gaboriaud, Bernard Humbert. Repercussions of size heterogeneity on the measurement of specific surface areas of colloidal minerals: Combination of macroscopic and microscopic analyses. American mineralogist, 2004, 89 (10), pp.1456-1462. 〈10.2138/am-2004-1013〉. 〈hal-01342996〉

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