Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
European Journal of Mineralogy Signup for GSW Email News
JOURNAL HOME HELP FEEDBACK/COMMNET SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
European Journal of Mineralogy; May, June 2006; v. 18; no. 3; p. 361-368; DOI: 10.1127/0935-1221/2006/0018-0361
© 2006 E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by JOZJA, N.
Right arrow Articles by CLINARD, C.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Articles

Incidence of lead uptake on the microstructure of a (Mg, Ca)-bearing bentonite (Prrenjas, Albania)

Nevila JOZJA1,*, Patrick BAILLIF1,*, Jean-CLAUDE TOURAY1, Fabrice MULLER1 and Christian CLINARD2

1 Institut des Sciences de la Terre d'Orléans (ISTO, UMR 6113), 1A rue de la Férollerie, 45071 Orléans Cedex 2, France
2 Centre de Recherche sur la Matière Divisée (CRMD, UMR 6619), 1B rue de la Férollerie, 45071 Orléans Cedex 2, France

* Corresponding authors: Nevila Jozja, e-mail: njozja{at}yahoo.com; Patrick Baillif, e-mail: patrick.baillif{at}univ-orleans.fr

The article addresses Pb uptake and microstructural/morphological modifications of a (Mg, Ca)-bentonite (Prrenjas, Albania) after interaction with solutions of elevated lead content. Comparison is made with a Wyoming montmorillonite transformed to the Mg-dominated form.

Characterised by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM), the Prrenjas bentonite is predominantly a smectite, containing 10% of interlayered illite, with associated kaolinite, antigorite, halloysite and minor chlorite. Significant magnesium is present in the octahedral layer in association with aluminium and iron. The CEC is rather high (above 80 meq/100 g). Magnesium and calcium are the main cations exchanged during CEC determinations and Pb uptake experiments. From TEM studies, microstructural units are composed by closely packed clay particles with 10 to 15 stacked platelets, in contrast with Wyoming montmorillonite.

Exchange experiments with lead nitrate on suspended clays have been performed with concentrations ranging from 10–5 M to 10–2 M. A comparable capacity of lead sorption is observed by Atomic Absorption Spectrometry (AAS) for Prrenjas bentonite and Wyoming montmorillonite. At increasing lead uptake, a higher reduction of hydration in interlayer space is observed by XRD on Wyoming montmorillonite. At the highest lead concentrations, X-ray Photoelectron Spectroscopy (XPS) analyses of the Prrenjas Bentonite reveal Pb sorption in a "non interlayer" site. TEM images of the same clay show a significant size decrease of microstructural units in relation to the lead sorption. On the contrary, the Mg-exchanged Wyoming montmorillonite is not modified.

Presumably, the "non interlayer lead" uptake results either from surface complexation at an edge site, or from ionic exchange with edge-exposed octahedral magnesium. Both mechanisms could initiate at edge-to-face contacts and result in a breaking process of the microstructural units.

Key-words: lead, bentonite, microstructure, adsorption, cation exchange, XPS, TEM.






JOURNAL HOME HELP FEEDBACK/COMMNET SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers