Podrobnosti záznamu

Název
    Effects of Iron Oxidation State and Organic Cations on Dioctahedral Smectite Hydration
Údaj o odpovědnosti
    Joseph W. Stucki, Jun Wu, Huamin Gan, Peter Komadel, Amos Banin
Autor
    Banin, Amos
    Gan, Huamin
    Komadel, Peter
    Stucki, Joseph W.
    Wu, Jun
Jazyk
    anglicky
Zdrojový dokument - seriál
    Clays and clay minerals
Svazek/č.
    Vol. 48, no. 2
Strany
    p. 290-298
Rok
    2000
Poznámky
    5 obr., 1 tab., 2 s.bibl.
    il.
    Zkr. název ser.: Clays and Clay Miner.
Předmětová skupina
    hydratace
    iontová výměna
    krystalová struktura
    minerály jílové
    montmorillonit
    smektity
    voda krystalová
    železo
Geografické jméno
    ČR-Čechy
    Hroznětín (Karlovy Vary)
    Slovensko
    Stebno (Ústí nad Labem)
    USA-Illinois
    USA-Missouri
Klíčové slovo
    Cations
    Dioctahedral
    Effects
    Hydration
    Iron
    Organic
    Oxidation
    Smectite
    State
Abstrakt (anglicky)
   Reduction of structural Fe in Na-exchanged dioctahedral smectite decrease swellability in water, but because clay interlayers also collapse in the process the concomitant effect on surface hydration energy is uncertain. This study examined the hydration behaviour of oxidized and reduced dioctahedral smectite clays exchanged with polar (Na) and weakly-polar (organic) cations to determine the nature of the surface before and after Fe reduction, and to determine if clay surfaces are hydrophilic or hydrophobic. The H2O content invarious dioctahedral smectites decreased if Na was replaced by tetramethylammonium (TMA), trimethylphenylammonium (TMPA), or hexadecyltrimethylammonium (HDTMA). Among the organo-clays, H2O adsorption decreased with increasing complexity of the cation. For oxidized smectites, those exchanged with TMPA retained less H2O than those exchanged with Na at all pressure.
   Reduction of Fe (III) to Fe(II) in the octahedral sheets decreased the swelling of Na-saturated smectites, apparently causing some previously swelling interlayers to collapse. If the Na interlayer cation was exchanged to alkylammonium after reduction, but prior to swelling-pressure measurements, the swelling increased or remained near constant, suggesting that the organo-cation disrupted the collapse process of the interlayers associated with the reduced smectite layers. Reduced TMPA-saturated smectite surfaces are more storngly hydrated if the octahedral sheet is reduced than if oxidized. Thus, reduction of structural Fe increases the hydration energy of smectite basal surfaces, but swellability could decrease or increase depending on the extent of interlayer collapse occurring with different exchangeable cations
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    21. 3. 2008
Datum importu
    8. 8. 2012