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| Titel |
Dissolution of smectite (beidellite) in acidic solutions using flow through reactors: New insights on interface reactions and the effect of crystal chemistry. |
| VerfasserIn |
Valentin Robin, Emmanuel Tertre, Olivier Regnault, Paul Sardini, Michael Descostes |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111021
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| Publikation (Nr.) |
 EGU/EGU2015-11081.pdf |
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| Zusammenfassung |
| In the context of remediation of acid mining environments (e.g., In Situ Leaching operated
mining sites), swelling clay minerals such as smectite can be considered as buffer
materials with the ability to remove contaminants from water (major and trace
elements) due to their high cation exchange capacity. Then, the stability of smectitic
minerals present in these environments and mechanisms occurring at the clay/water
interface have to be assessed in acidic conditions. Dissolution rate of beidellite
(di-octahedral smectite with tetrahedral charge), a common swelling clay mineral
in surface and subsurface natural environment, was studied in acidic solutions at
25Ë C under far from equilibrium conditions. The 1, and the presence of amorphous Si enriched layer can be
reasonably assumed in some cases from interpretation of aqueous concentrations and
the characterization of the solid phase (X-ray diffraction and FTIR spectroscopy
measurements). Beidellite dissolution rates normalized to the sample mass (mol.g-1.s-1)
were obtained from Si and Al concentrations at steady state dissolution conditions.
Calculated rates were compared with those previously obtained on montmorillonite
(di-octahedral smectites with octahedral charge) and reported from several published works.
It appears that the beidellite dissolution rates are in average ten times lower than
montmorillonite ones. This observation implies a significant effect of the smectite
crystal chemistry (i.e., amount of Al3+ versus Mg2+ or Fe3+ substitution in the
structure) on its stability. Then, the good stability of beidellite at low pH conditions
is of interest in the context of environmental remediation because such behavior
allows to preserve the sorption capacity of smectites towards aqueous contaminants. |
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