Record details

    Methylene blue interactions with reduced-charge smectites
Statement of responsibility
    Juraj Bujdák, Marián Janek, Jana Madejová, Peter Komadel
    Bujdák, Juraj
    Janek, Marián
    Komadel, Peter
    Madejová, Jana
Source title - serial
    Clays and clay minerals
    Vol. 49, no. 3
    p. 244-254
    4 obr., 3 tab., 3 s.bibl.
    Zkr. název ser.: Clays and Clay Miner.
Subject group
    iontová výměna
    ložisko bentonitu
    spektrum absorbční
Geographical name
    Česká republika
    Horní Dunajovice (Znojmo)
    Stebno (Ústí nad Labem)
Abstract (in english)
   The objective of this work was to prepare series of reduced-charge materials from different parent Li-saturated dioctahedral smectites, to investigate the effects of temperature, chemical composition and charge location in smectites on the charge reduction and to characterize reduced-charge smectites (RCSs) using methylene blue (MB) adsorption. The layer charge decrease, induced by Li fixation, is correlated with the trends in the spectra of MB-RCS dispersions in the visible region (VIS) spectra. Distribution of the negative surface charge of the clay minerals controls the distance between the adsorbed MB cations and thus affects the formation of MB dimers and higher and higher agglomerates. Because each form of MB (monomer, dimer, higher, agglomerate, J-aggregates) absorbs light at a different wavelength, the VIS spectra of MB depend sensitively on the charge density at the clay surface.
   Both cation exchange capacity (CEC) values and spectra of MB-clay dispersions clearly detect extensive reduction of the layer-charge density in reduced-charge montomorillonites (RCMs) upon Li-thermal treatment. The extent of charge reductions depends on the temperature of the thermal treatment, as well as on the octahedral charge of the montmorillonite. Reduction of the layer charge proceeds to a much lesser extent for smectites with mainly tetrahedral charge and high Fe content (Fe-rich beidellite and ferruginous smectite). Both CEC data and MB spectra detect only a slight decrease of the layer charge density, which relates to the low octahedral charge of these minerals
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    21. 3. 2008
Import date
    8. 8. 2012