Authors:L. Chmielarz, M. Zbroja, P. Kuśtrowski, B. Dudek, A. Rafalska-Łasocha, and R. Dziembaj
Alumina, zirconia and titania pillared montmorillonites additionally modified with silver were tested as catalysts of NO reduction
with NH3 or C2H4. Ammonia was much more effective reducer of NO than ethylene. The silver containing TiO2-pillared clay has been found to be the most active catalyst for NO reduction both with NH3 or C2H4. Oxidation of the reducing agents by oxygen limited the NO conversion in the high temperature region. The ammonia and nitric
oxide adsorption sites were studied by the temperature programmed desorption methods (TPD).
Authors:D. Karamanis, P. Assimakopoulos, and N. Gangas
The selective uptake of strontium by a specially tailored aluminum pillared montmorillonite was investigated. Selective exchange
kinetics revealed a fast component of the order of less than one hour, while exchange isotherms revealed the preference for
strontium uptake over sodium and calcium with separation factors α
=50 and α
=2. In an environment of rumen liquid taken from slaughtered sheep, 26% of strontium was removed by 1 g and 40% by 3 g of
Authors:D. Karamanis, X. Aslanoglou, P. Assimakopoulos, and N. Gangas
The methods of PIGE and XRF were used to determine the elemental composition and the structural formulae of a specially tailored
PILC material during the steps of its preparation. The CEC, a crucial property for the characterization of a cation exchanger,
was monitored through all stages of preparation. In addition, the charge carried by the pillars, a critical quantity of the
pillaring process, was estimated. Exchange isotherms of strontium and cesium were performed through the use of radiotracers'
exchange isotherms of137Cs and85Sr with typical ψ-ray spectroscopy. These isotherms were of the Langmuir type and PILCs adsorption capacity was determined.
The latter property was compared with the CEC determined by the elemental analysis and was found equal to the amount of the
exchangeable interlamellar sodium ions.
Authors:R. Marinkovic-Neducin, E. Kiss, T. Cukic, and D. Obadovic
The purified bentonite parent clay, fraction ≤; 2 mm of montmorillonite type, has been pillared by various polyhydroxy cations,
Al, AlFe and AlCu, using conventional pillaring methods. The thermal behavior of PILCs was investigated by combination of
X-ray diffraction (XRD), thermal analysis (DTA, TG) and low temperature N2 adsorption/desorption (LTNA). Thermal stability
of Al-, AlFe- and AlCu-PILC samples was estimated after isothermal pretreatment in static air on the temperatures 300, 500,
600 and 900C. Crucial structural changes were not registered up to 600C, but the fine changes in interlayer surrounding
and porous/microporous structure being obvious at lower temperatures, depending on the nature of the second pillaring ion.
AlFe-PILC showed higher thermal stability of the texture, the AlCu-PILC having lower values and lower thermal stability concerning
both overall texture and micropore surface and volume. Poorer thermal stability of AlCu-PILC sample at higher temperatures
was confirmed, the presence of Cu in the system contributing to complete destruction of aluminum silicate structure, by 'extracting'
aluminum in stabile spinel form.
Emanation Thermal Analysis (ETA), based on the measurement of the release of radon from previously labelled samples, has been
used for 'in-situ’ characterisation of the morphology changes of intercalated montmorillonitic clay. The thermal behaviour
of hydroxyaluminium intercalated montmorillonite was monitored in course of the preparation of alumina pillared montmorillonite,
making possible to determine optimal temperature for the isothermal treatment of the intermediate product. Moreover, the thermal
stability of alumina pillared montmorillonite porous structure was determined from the ETA data. A good agreement of ETA data
and surface area, XRD patterns. DTA, and TG resulted was found.
Fig. 1 depicts the powder small angle X-ray diffraction pattern of the Na-montmorillonte clay and basal spacing d 001 of Cu(II) Schiff base complexes pillaredmontmorillonites. The basal spacing (d 001 ) of [Cu