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Étude de matériaux argileux albanais. Caractérisation "multi-échelle" d'une bentonite magnésienne.

Abstract : This study adresses the clay/metallic cation interaction with respect to their part played in landfill sites. The present study is aimed to correlate the permeability variations with structural and textural modifications, produced as a result of heavy metal sorption by the clay. The clay used for the experimental works has been chosen among three Albanian samples because of its bentonite-like characteristics. It is originated from Prrenjas region, and derived from supergene alteration of ultrabasic rocks. This bentonite is characterized by a high value of CEC (90 meq/100g), Mg2+ as a major interlayer cation and the presence of interstratified illite (11%). The XRD, TEM and SAXS allow to identify the mineralogy and the special morphology of Prrenjas bentonite, i.e. microagregates made of thiny particles, strongly different from Wyoming "standard" montmorillonite. The exchange experiments with Pb(NO3)2 on suspended clays, have been performed with concentrations ranging from 10-5M to 10-2M. In addition to a study of micro structural and textural, several effects of lead sorption are evidenced. A reduction of hydration in interlayer space is observed by XRD. TEM images have shown, the fragmentation of microagregates leading to the initial particles. On the contrary, the Wyoming montmorillonite shows very few modification. XPS analyses have confirmed a lead sorption on the clay surface more important for the Prrenjas clay than for the Wyoming montmorillonite. Percolation of 10-2M Pb(NO3)2 solution was carried out until a total sorption of Pb2+, into a compacted clay. A great increase of permeability (a factor 40) is observed, much higher than that observed in the Wyoming clay (a factor 2). In percolated sample, observation using cryo-SEM reveals the formation of interconnected micro-cracks nets, explaining the large flow increase. Finally, this work, shows that permeability increase, observed for Prrenjas bentonite, is linked to structural modifications at different scales of clay organisation.
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https://tel.archives-ouvertes.fr/tel-00003740
Contributor : Nathalie Pothier <>
Submitted on : Wednesday, November 12, 2003 - 8:38:36 AM
Last modification on : Thursday, March 5, 2020 - 6:49:00 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:03:21 PM

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  • HAL Id : tel-00003740, version 1

Citation

Nevila Jozja. Étude de matériaux argileux albanais. Caractérisation "multi-échelle" d'une bentonite magnésienne.. Minéralogie. Université d'Orléans, 2003. Français. ⟨tel-00003740⟩

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