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Thermal behaviour of organically modified smectites
Plevová, Eva ; Vaculíková, Lenka ; Valovičová, Věra ; Simha Martynková, G.
The smectites were modified with different types of alkylammonium cations. The X-ray powder diffraction was used to calculate the values of the basal space of the modified smectites to confirm the intercalation of cations into the structure. The montmorillonites were also characterized by means of FTIR spectroscopy, which proved sorption or intercalation of the alkylammonium cations too. Thermal behaviour of the smectites was investigated by simultaneous thermogravimetry and differential thermal analysis. The temperatures of dehydratation and dehydroxylation and the temperatures related to total melting and recrystallization generally changed. Study of temperatures changes together with determination of kinetic parameters helped to obtained a comprehensive assessment of smectite thermal stability.
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Characterization of fine-grained montmorillonite fractions suitable for composite preparation
Valovičová, Věra ; Vaculíková, Lenka ; Plevová, Eva ; Dolinská, S. ; Znamenáčková, I. ; Danková, Z.
The aim of this experimental study was to characterize a fine-grained fraction of montmorillonites (SAz-2, STx-1, SWy-2 and Kunipia-F). It was investigated in order to provide more precise information of used montmorillonites than could be obtained by analysis of the unfractioned montmorillonites. At first, the fine fraction of montmorillonites were prepared by sedimentation and activation by means of Na2CO3. The prepared clay materials were characterized by the X-ray diffraction analysis and FTIR spectroscopy. The thermal behaviour of the studied samples was determinated according to the characteristic temperatures obtained from TG/DTA curves. The temperatures of dehydratation and dehydroxylation were evaluated and kinetic parameters were also calculated. The porosity and surface properties of the studied samples were gained by the nitrogen adsorption measurements. The obtained results confirmed that the fine fraction of montmorillonites could be a suitable material for subsequent preparation of composites with enhanced sorption properties, especially montmorillonite/MnO2 composite.
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Application of bentonite-manganese oxide composites in removal of heavy metals
Dolinská, S. ; Znamenáčková, I. ; Tomčová, J. ; Valovičová, Věra ; Vaculíková, Lenka ; Plevová, Eva
The paper is aimed on the using of non-homogeneous bentonites coated by manganese oxides for the removal of heavy metal cations from the water solutions. In the first stage Slovak natural bentonite was converted to sodium form using by Na2CO3 as the activating agent. After that the manganese oxides were precipitated on the surface of natural and sodium activated bentonite, respectively. The structural changes before and after the modifications of bentonites were characterized by X-ray diffraction analyses and X-ray photoelectron spectroscopy. To compare the sorption properties of the natural bentonite and modified bentonites, sorption experiments of Cd2+ from aqueous solutions were done.
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Thermal behaviour of organically modified clays
Plevová, Eva ; Vaculíková, Lenka ; Vítámvásová, E. ; Šugárková, Věra ; Martynková, G.S.
The clay minerals were modified by two alkylammonium cations under sorption procedure. T X-ray powder diffraction and FT-IR spectroscopy were used to evaluate the intercalation process of organic cations int the clay structure. The organo - montmorillonites exhibited IR spectra giving evidence about sorption or intercalation of the alkylammonium cations. The enhancement of the basal spacing obtained by X-ray diffraction confirmed the intercalation process of cations into montmorillonite and vermiculite samples. Thermal behaviour of the modified clay minerals was investigated by simultaneous thermogravimetry and differential thermal analysis. The organically modified montmorillonites exhibited the higher values of temperatures related to the total melting. Also the temperatures of exotherm effects connected to recrystallization and transformation increased with the concentration of alkylammonium salts. The temperatures of dehydratation and dehydroxilation decreased with concentration of alkylammonium cations. Vermilulite samples showed generally reducing of their thermal stability.
Plný tet: UGN-0393204 -  PDF
Plný text: content.csg - PDF
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Stanovení minerálů v břidlicích pomocí infračervené spektroskopie a chemometrických metod
Ritz, M. ; Vaculíková, Lenka ; Plevová, Eva
V práci byla testována možnost využití infračervené spektroskopie ve spojení s chemometrickými metodami ke stanovení chloritu, muskovitu, albitu a křemene v břidlicích. Za tímto účelem bylo použito 86 vzorků břidlic z různých lokalit v České republice. Jako referentní kvantitativní metoda byla zvolena Rietveldova metoda práškové difrakční rentgenové analýzy. Infračervená spektra analyzovaných vzorků břidlic byla naměřena technikou bromidových tablet a difúzně reflekční technikou. Infračervená spektra a výsledky referentní metody byly použity pro konstrukci chemometrických modelů metodou regrese částečně nejmenších čtverců. Na kontrolních vzorcích břidlic byla testována shodnost výsledků predikovaných z chemometrických modelů s výsledky referentní metody.
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Ověření přítomnosti injektážního média v injektovaných horninách - důkazní metody
Ščučka, Jiří ; Vaculíková, Lenka
Častým požadavkem při laboratorních analýzách geokompozitních materiálů řady polyuretanová pryskyřice - hornina (zemina) nebo polyuretanová pryskyřice - stavební hmota bývá ověření přítomnosti chemického injektážního média v pórovém systému jemnozrnných zemin nebo v jemných trhlinách injektovaných skalních hornin a stavebních konstrukcí. Pro tento účel lze použít- optické fluorescenční mikroskopie spojené se zpracováním digitálního obrazu, -infračervené spektroskopie práškového vzorku. Uvedené techniky a zejména jejich kombinace představují účinnou důkazní metodu pro potvrzení přítomnosti injektážní hmoty v injektovaných horninách.
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