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Comprehensive physicochemical study of dioctahedral palygorskite-rich clay from Marrakech High Atlas (Morocco)

Rhouta, Benaïssa and Zatile, Ezzouhra and Bouna, Lahcen and Lakbita, Omar and Maury, Francis and Daoudi, Lahcen and Lafont, Marie-Christine and Amjoud, M'barek and Senocq, François and Jada, Amane and Aït Aghzzaf, Ahmed Comprehensive physicochemical study of dioctahedral palygorskite-rich clay from Marrakech High Atlas (Morocco). (2013) Physics and Chemistry of Minerals, 40 (5). 411-424. ISSN 0342-1791

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Official URL: http://dx.doi.org/10.1007/s00269-013-0579-3

Abstract

This study is devoted to the physicochemical and mineralogical characterizations of palygorskite from Marrakech High Atlas, Morocco. The raw clay and its Na?-saturated\ 2 lm fraction were characterized using chemical, structural, and thermal analytical techniques. Measurements of specific surface area and porous volume are reported. The clay fraction was found to be made up of 95 %of palygorskite and 5 % of sepiolite. An original feature of this palygorskite is its deficiency in zeolitic H2O. The half-cell structural formula of its dehydrated form was determined on the basis of 21 oxygens to be (Si7.92Al0.08)(Mg2.15Al1.4Fe0.4Ti0.05h1)(Ca0.03 Na0.08K0.04)O21, while the hydrated form could be formulated as (Si7.97Al0.03)(Mg2.17Al1.46Fe0.40Ti0.05)(Ca0.03Na0.07K0,03) O20.18(OH)1.94(OH2)3.8812.43H2O. These formulas showthat the (Al3??Fe3?)/Mg2? ratio is around 0.84, revealing a pronounced dioctahedral character. Further, inside its octahedral sheet, it was determined that the inner M1 sites are occupied by vacancies, whereas the M2 sites are shared between 90 % of trivalent cations (78 % for Al3? and 22 % for Fe3?), 7.5 % of Mg2+, and 2.5 % of Ti4+, all of them linked to 1.94 of structural hydroxyls. The two remaining Mg2+ by half-cell occupy edge M3 sites and are coordinated to 3.88 molecules of OH2. Channels of this palygorskite are deficient in zeolitic H2O since they contain only 2.43 H2O molecules.A correlation was found between these results and the observation of very intense and well-resolved FTIR bands arising from dioctahedral domains (mainly Al2OH, Fe2OH, and AlFeOH) along with very small responses from a trioctahedral domain (Mg3OH). Accordingly, a schematic representation of the composition of the octahedral sheet was proposed. The cation exchange capacity, specific surface area, and total pore volume were also assessed to be ca. 21.2 meq/100 g, 116 m2/g, and 0.458 cm3/g, respectively.

Item Type:Article
Additional Information:Thanks to Springer editor. The definitive version is available at http://link.springer.com The original PDF of the article can be found at Springer website : http://link.springer.com/article/10.1007%2Fs00269-013-0579-3
HAL Id:hal-01172017
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > University of Cadi Ayyad - UCAM (MOROCCO)
Other partners > Université de Haute Alsace - UHA (FRANCE)
Laboratory name:
Funders:
Convention de coopération CNRST-Maroc/CNRS-France - Convention de coopération Académie Hassan II des Sciences et Techniques-Maroc/CSIC-Espagne
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Deposited By: cirimat webmestre
Deposited On:06 Jul 2015 14:37

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