Jana Madejová

Institute of Chemistry of the Slovak Academy of Sciences

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Peter Komadel

Institute of Inorganic Chemistry of the Slovak Academy of Sciences

Helena Pálková

Slovak Academy of Sciences

ĽJ

Ľuboš Jankovič

Institute of Chemistry of the Slovak Academy of Sciences

Sabine Petit

Université de Poitiers

Martin Pentrák

University of Illinois Urbana-Champaign

Juraj Bujdák

Slovak Academy of Sciences

Peter Uhlík

Comenius University Bratislava

VŠ

V. Šucha

Comenius University Bratislava

Michal Slaný

Institute of Inorganic Chemistry of the Slovak Academy of Sciences

M. Janek

Slovak University of Technology in Bratislava

Cooperative Institutions

Slovak Academy of Sciences

Institute of Inorganic Chemistry of the Slovak Academy of Sciences

Institute of Chemistry of the Slovak Academy of Sciences

Comenius University Bratislava

Slovak University of Technology in Bratislava

VSB - Technical University of Ostrava

Centre National de la Recherche Scientifique

Balıkesir University

Polish Academy of Sciences

Czech Academy of Sciences, Institute of Inorganic Chemistry

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Near-infrared study of the interaction of pyridine with acid-treated montmorillonite

Vibrational Spectroscopy (2014)

Jana Madejová Helena Pálková Ľuboš Jankovič

Silanol

10.1016/j.vibspec.2014.11.003

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Citations (16)

Influence of Grinding and Sonication on the Crystal Structure of Talc

Clays and Clay Minerals (2015)

Vladimír Čavajda Peter Uhlík Arkadiusz Derkowski Mária Čaplovičová Jana Madejová

Talc

Sonication

Crystal (programming language)

Thermogravimetry

10.1346/ccmn.2015.0630405

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Citations (22)

Application of vibrational spectroscopy to the characterization of phyllosilicates and other industrial minerals

Mineralogical Society of Great Britain & Ireland eBooks (2011)

Jana Madejová Etienne Balan Sabine Petit

Chapter 6: Application of vibrational spectroscopy to the characterization of phyllosilicates and other industrial minerals J. Madejová, E. Balan and S. Petit This chapter shows how infrared (IR) and Raman spectroscopies contribute to better understanding of industrial minerals. These non-destructive techniques provide information on the chemical composition, structure, bonding and reactivity of molecules and/or minerals.

Characterization

10.1180/emu-notes.2010.emu9-6

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Citations (26)

Characterization and crystal chemistry of an Fe-rich montmorillonite from Ölberg, Germany

Clay Minerals (2002)

Sabine Petit Jacinthe Caillaud D. Righi Jana Madejová Françoise Elsass

Abstract An Fe-rich smectite from Ölberg (Germany) was characterized using X-ray diffraction, infrared spectroscopy and analytical electron microscopy. Progressive reduction of the octahedral charge was performed through the Hofmann & Klemen effect at increasing temperatures. The sample was heterogeneous, consisting of two smectite populations. One population, which comprises a minor portion of the sample, is an ‘Fe 3+ -montmorillonite’ with little or no tetrahedral charge and Fe 3+ as the major octahedral cation. The other population, a major constituent of the sample, contains less Mg and more Al than the first one and exhibits some tetrahedral charge. This fraction may be considered as an inter-grade between nontronite (dominant tetrahedral charge) and Fe 3+ -montmorillonite (dominant octahedral charge). These two populations may occur as separate particles but also as interstratified layers.

Nontronite

Structural formula

Crystal Chemistry

10.1180/0009855023720034

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Citations (62)

Preparation and infrared spectroscopic characterization of reduced-charge montmorillonite with various Li contents

Clay Minerals (1996)

Jana Madejová Juraj Bujdák Will P. Gates Peter Komadel

Abstract A series of reduced-charge montmorillonites (RCMs) was prepared from Li-montmorillonite from Jelšový Potok (Slovakia) by heating at various temperatures (105–210°C for 24 h. The amount of fixed Li, 0.09–0.67 per O 20 (OH) 4 , increased with increasing temperature, confirming preparation of a set of samples of variable layer charge from the same parent Li-montmorillonite by varying only the preparation temperature. Infrared spectroscopy revealed that Li was trapped in the hexagonal cavities of the tetrahedral sheet at all temperatures. Partial deprotonation of the samples, reflected in the decrease of the intensities of the OH-bending bands, was observed after treatments above 120°C. Analysis of the OH-stretching region showed Li in the previously vacant octahedra in the samples heated above 150°C. Weak inflections near 660 and 720 cm −1 confirmed development of local trioctahedral character of octahedral cations coordinated with OH groups in the sample heated at 210°C. Gradual decrease of the layer charge due to Li fixation led to a shift of the Si-O stretching band to higher frequencies and to the appearance of new, pyrophyllite-like bands at 1120 and 419 cm −1 .

Pyrophyllite

Structural formula

10.1180/claymin.1996.031.2.09

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Citations (84)

Alkali-Activated Metakaolins: Mineral Chemistry and Quantitative Mineral Composition

Minerals (2022)

Marta Valášková Zdeněk Klika Jozef Vlček Lenka Matějová Michaela Topinková

The reaction products resulting from the alkali-activation of metakaolin are impacted by the composition of the initial kaolin, and amount of alkali-activated kaolinite and water. The present study focused on analyzing these parameters on the metakaolins calcined at 800 °C from three kaolins, and the metakaolins’ alkali activation for 2, 3 and 28 days. The first objective was to evaluate the mineral chemistry and quantitative mineral phase composition from the bulk chemical analysis using the chemical quantitative mineral analysis (CQMA) procedure and conduct a comparison of the chemistry of the metakaolins after alkali activation for 28 days according to the elements Al, Si, Na and K, using the leaching test in distilled water. The second task was to search for possible relationships between the quantitative number of phases in alkali-activated metakaolins and compressive strength. The main methods used for the characterization of material were X-ray fluorescence, X-ray diffraction, thermal TG/DTA and infrared spectroscopy. Metakaolins alkali activated for 28 days contained crystalline quartz, muscovite, orthoclase, and unreacted metakaolinite contained zeolite A (Z-A), hydrosodalite (HS) and thermonatrite (TN) in the amorphous/weakly crystalline phase. The compressive strengths (CS) from 6.42 ± 0.33 to 9.97 ± 0.50 MPa are related positively to H2O+ and H2O bound in HS and TN.

Metakaolin

Muscovite

Orthoclase

10.3390/min12111342

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Citations (7)

Experimental interactions of Slovak bentonites with metallic iron

Geologica Carpathica (2009)

Marek Osacký Miroslav Honty Jana Madejová T. Bakas V. Šucha

Experimental interactions of Slovak bentonites with metallic iron The experimental stability of four bentonites and one K-bentonite from Slovak deposits in the presence of iron was studied to simulate the possible reactions of clays (bentonite barrier) in the contact with Fe containers in a nuclear waste repository. The batch experiments were performed at 60 °C for 30 and 120 days in aerobic conditions. The reaction products were examined by XRD, FTIR, and Mössbauer spectroscopies and CEC (cation exchange capacities) were determined. Reaction solutions were analysed for selected elements using AAS (atomic absorption spectrometry). The results show that bentonites do not interact equally with metallic iron. Bentonites from the Jelšový Potok, Kopernica and Lieskovec deposits reacted similarly whereas the interaction between the bentonite from Lastovce and the iron was less intensive. The lower reactivity of the bentonite from Lastovce can be explained by its low content of smectite. During iron-clay interactions the iron was consumed and Fe oxides (magnetite, lepidocrocite) were formed. Decrease of the smectite diffraction peaks intensity and CEC values during the experiments show rather the rearrangement of the original smectite crystals than dissolution of smectite. In the K-bentonite from the Dolná Ves deposit where the mixed-layer illite-smectite is present instead of smectite, the dissolution of illite-smectite was observed along with the neoformation of smectite. The structure of illite-smectite deteriorated more than the structure of smectites which suggests that this mixed-layer illite-smectite is much less stable in the presence of iron than smectites.

Bentonite

Illite

Lepidocrocite

10.2478/v10096-009-0039-7

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Citations (21)

Nanocomposites of Natural Rubber Containing Montmorillonite Modified by Poly(2-oxazolines)

Materials (2024)

Peter Boháč Zuzana Nógellová Miroslav Šlouf Juraj Kronek Ľuboš Jankovič

Nanocomposites with a natural rubber (NR) matrix containing organomodified montmorillonite (MMT) as a precursor of nanoparticles were prepared using two different polyoxazolines as surface modifiers of the MMT. The materials were characterized by X-ray diffraction, transmission electronic microscopy and ultimate mechanical properties, and parameters obtained by DMTA method (storage and loss moduli and loss tangent) were determined. It was found that the effect of nanofillers presence has a significant effect on tensile strength as well as elongation at break, which are higher for materials with higher viscosity due to the presence of carbon blacks compared to the composites without carbon blacks. From the two modifiers, poly(2-ethyl-2-oxazoline) was identified as a prospective modifier for surface modification of MMT used as the possible additive for tyre treads exhibiting optimal balance between fuel consumption and safety of driving concerning breaking action and lateral breakaway.

Elongation

Surface Modification

Mooney viscosity

10.3390/ma17164017

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Effects of chemical composition and temperature of heating on the infrared spectra of Li-saturated dioctahedral smectites. (II) Near-infrared region

Clay Minerals (2000)

Jana Madejová Juraj Bujdák Sabine Petit Peter Komadel

Abstract Diffuse reflectance spectra in the near-infrared region are presented for Li-saturated smectites heated up to 200°C. The smectites included three montmorillonites, an Fe-beidellite and a ferruginous smectite. Unheated samples showed a complex band near 7060 cm -1 assigned to the first overtone of the OH-stretching mode of structural hydroxyl groups and bound H 2 O. The OH combination bands appeared in the 4600-4300 cm -1 region. Spectra of heated montmorillonites showed an upward shift and splitting of the OH-overtone band into two components near 7170 and 7110 cm -1 . The presence of a band near 7170 cm -1 , assigned to the overtone of the AlMgLiOH-stretching vibration, implied that local trioctahedral domains were created upon Li(I) fixation in the previously vacant octahedral positions of montmorillonites. The OH combination bands were shifted to higher frequencies and a new band appeared near 4472 cm -1 in the spectra of montmorillonites heated to temperatures in excess of 130°C. No features indicating Li(I) in the structure of Fe-beidellite or ferruginous smectite were observed in the NIR spectra.

Overtone

10.1180/000985500547205

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Citations (26)

Synthesis of ammonium illite

Sucha Ľ. Kuchta Jana Madejová Françoise Elsass Will P. Gates

Illite

Source

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