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The results of FT-IR spectroscopic studies of coal fly ashes, originated from various polish power plants are reported. The results of MIR investigations were compared to the X-ray diffraction (XRD) measurements and chemical analyses. They are mainly composed of silica, alumina and lime. The infrared spectrum in the middle range can be used to describe both the structure of phases present in the fly ash and to identify the characteristic elements of the individual components of ash. The results indicate that the amount of aluminosilicate and its Si/Al ratio induce a shift in the T-O stretching band appearing at 950-1100 cm-1. Moreover, FWHM of these bands indicates the participation of the crystalline phase relative to amorphous. The presence of carbonate phases generates substantial changes in the 1450-1400 cm-1 area of the spectra. The presence of such phases as anhydrite, mullite or illite has also been established on the basis of IR spectra. [ABSTRACT FROM AUTHOR]

Abstract: This work presents the results of FT-IR spectroscopic studies of heavy metal cations (Ag+, Pb2+, Zn2+, Cd2+ and Cr3+) immobilization from aqueous solutions on natural sorbents. The sorption has been conducted on sodium forms of zeolite (clinoptilolite) and clay minerals (mixtures containing mainly montmorillonite and kaolinite) which have been separated from natural Polish deposit. In the next part of the work both sorbents were used to obtain new building composites. It was proven those heavy metal cations’ sorption causes changes in IR spectra of the zeolite and clay minerals. These alterations are dependent on the way the cations were sorbed. In the case of zeolite, variations of the bands corresponding to the characteristic ring vibrations have been observed. These rings occur in pseudomolecular complexes 4–4–1 (built of alumino- and silicooxygen tetrahedra) which constitute the secondary building units (SBU) and form spatial framework of the zeolite. The most significant changes have been determined in the region of pseudolattice vibrations (650–700cm−1). In the instance of clay minerals, changes in the spectra occur at two ranges: 1200–800cm−1 – the range of the bands assigned to asymmetric Si–O(Si,Al) and bending Al–OH vibrations and 3800–3000cm−1 – the range of the bands originating from OH− groups stretching vibrations. Next results indicate possibilities of applying the used natural sorbents for the obtainment of new building materials having favourable composition and valuable properties. The zeolite was used for obtaining autoclaved materials with an addition of CaO, and the clay minerals for ceramic sintered materials with an addition of quartz and clinoptilolite were produced. FT-IR studies were also conducted on the obtained materials. [Copyright &y& Elsevier]

Abstract: Calculated vibrational spectra of aluminosilicate D4R and D6R structural units have been derived using ab initio methods. These units constitute the models of secondary building units (SBU) of two important structural zeolite groups. In the calculations, the model of isolated double four- and six-membered rings containing both AlO4 and SiO4 tetrahedra has been used. Based on the results of calculations, normal vibrations of the units have been visualized. This has enabled us to identify the bands in the spectra obtained. In particular, distinguishment of the characteristic ring or pore-opening vibrations occurring in these units has been possible. The effect of Al→Si substitution in tetrahedral positions on the spectra shape has been also analysed. The calculated results obtained have been applied to interpret experimental spectra of selected zeolites. Their frameworks are formed by spatial connection of structural units in three directions. For the interpretation, the spectra of zeolites whose structure is exclusively composed by the connection of the structural units studied have been chosen. [Copyright &y& Elsevier]

Abstract: Hydrolytic polycondensation process, also called sol–gel process, leads to formation of xerogels from simple molecules e.g. most widely used tetraethoxysilane (TEOS). In the presented work 2,4,6,8-tetraethoxy-2,4,6,8-tetramethylcyclotetrasiloxane – D4(OEt)4 was applied as the molecular precursor. Polycondensation reactions were performed in the presence of Bu4NF or HCl/NH4OH as the catalysts. The obtained xerogels were studied by FT-IR, MAS-NMR and XRD methods. Depending on the condensation process conditions, structure of the resulting materials varied from octahedral cage unit (T8) through a ladder chain to random structure. Dried xerogels were heated at the temperature of 800 and 1000°C in argon or air atmosphere (pyrolysis or ceramization). In the atmosphere of argon SiC x O y glass materials were obtained, while in air silica glass was formed. Their properties depended on the pyrolysis conditions as well as on the xerogel structure. IR spectroscopy results allowed to conclude about the short range order in amorphous xerogel and glass materials. [Copyright &y& Elsevier]

Abstract: It is known that the chemical activity phenomenon is characteristic for some inorganic glasses and they are able to participate in biological processes of living organisms (plants, animals and human bodies). An example here is the selective removal of silicate–phosphate glass components under the influence of biological solutions, which has been applied in designing glasses acting as ecological fertilizers of controlled release rate of the nutrients for plants. The structure of model silicate–phosphate glasses containing the different amounts of the glass network formers, i.e. Ca2+ and Mg2+, as a binding components were studied. These elements besides other are indispensable of the normal growth of plants. In order to establish the function and position occupied by the particular components in the glass structure, the glasses were examined by FTIR spectroscopy (with spectra decomposition) and XRD methods. It has been found that the increasing amount of MgO in the structure of silicate–phosphate glasses causes the formation of domains the structure of which changes systematically from a structure of the cristobalite type to a structure corresponding to forsterite type. Whilst the increasing content of CaO in the structure of silicate–phosphate glasses causes the formation of domains the structure of which changes from a structure typical for cristobalite through one similar to the structure of calcium orthophosphate, to a structure corresponding to calcium silicates. The changing character of domains structure is the reason of different chemical activity of glasses. [Copyright &y& Elsevier]

In this work the influence of the activator concentration on the inorganic polymer structure based on metakaolin was investigated. Changes in the aluminosilicate structure of the metakaolin during alkali-activation have been analyzed in detail on the basis of XRD, SEM and FT-IR analysis and ATR/FT-IR spectra as well. Based on the change of attenuated total reflectance FT-IR spectra over time at 80 °C, the zeolitization/geopolymerization process can be analyzed. Image 1 • The study investigated the effect of alkali activation on the ATR-FTIR spectra. • Treatment of metakaolin with the use NaOH solutions was carried out. • We used the infrared spectra to describe the zeolite formation progress. [ABSTRACT FROM AUTHOR]