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This work presents results of FT-IR spectroscopic studies of anions-chromate, phosphate and arsenate - sorbed from aqueous solutions (different concentrations of anions) on zeolites. The sorption has been conducted on natural zeolites from different structural groups, i.e. chabazite, mordenite, ferrierite and clinoptilolite. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA+) and organo-zeolites were obtained. External cation exchange capacities (ECEC) of organo-zeolites were measured. Their values are 17mmol/100g for chabazite, 4mmol/100g for mordenite and ferrierite and 10mmol/100g for clinoptilolite. The used initial inputs of HDTMA correspond to 100% and 200% ECEC of the minerals. Organo-modificated sorbents were subsequently used for immobilization of mentioned anions. It was proven that aforementioned anions' sorption causes changes in IR spectra of the HDTMA-zeolites. These alterations are dependent on the kind of anions that were sorbed. In all cases, variations are due to bands corresponding to the characteristic Si-O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolites). Alkylammonium surfactant vibrations have also been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO42-, AsO43- and PO43- ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of anions were determined by spectrophotometric method. [ABSTRACT FROM AUTHOR]

The results of vibrational spectroscopy studies of zeolites synthesized from expanded perlite using hydrothermal method were presented. The starting material used was a waste obtained during the production of expanded perlite. The effects of synthesis temperature and time, as well as NaOH concentration and solid to liquid ratio on the obtained products were determined. The resulting materials were analyzed regarding phase composition. In particular, the structures of materials were examined using FT-IR spectroscopy in the middle and far infrared ranges as well as Raman spectroscopy. The results were compared to the XRD and XRF measurements, as well as SEM observations. It has been found that by using a sufficiently high concentration of NaOH, it is possible to efficiently synthesize zeolite at temperatures above 50 °C. The presence of zeolite phase was confirmed by the measurement of spectra. Pseudolattice range, i.e. 800-400 cm -1 , was analyzed in detail. In this range, bands associated with the ring vibrations occur. They are characteristic for secondary building units (SBU) existing in zeolite structure. Depending on time, temperature and NaOH concentration, zeolite X, A, Na-P1 and hydroxysodalite have been identified as synthesis products in autogenous pressure. [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]