Preparation and properties of organomineral adsorbent obtained by sol-gel technology

Organomineral nanocomposite material has been obtained by sol-gel method through in situ formation of inorganic network in the presence of organic polymer. The most common silica precursor tetraethoxysilane (TEOS) and polysaccharide chitosan solution were used for the sol-gel transformations. The obtained chitosan-silica nanocomposite has been characterized by the physicochemical methods such as differential scanning calorimetry-thermogravimetry-mass spectrometry, Fourier transform infrared spectroscopy-thermogravimetry, elemental analysis, nitrogen adsorption/desorption isotherms, scanning electron microscopy, Fourier transform infrared spectroscopy to determine possible interactions between silica and chitosan macromolecules. Thermal destruction and products from gaseous phase in atmosphere of air and nitrogen were studied. It was found that introducing chitosan in silica network drastically change behavior of polymer during heat treatment in inert atmosphere. Adsorption of microquantities of Zn(II), Cu(II), Fe(III), Cd(II) and Pb(II) cations from the aqueous solutions by the obtained composite has been studied in comparison with the chitosan beads, previously cross-linked with glutaraldehyde. The adsorption capacity and kinetic sorption characteristics of the composite material were estimated. The obtained data were analyzed using the Langmuir and Freundlich isotherms, and the characteristic parameters for each isotherm were determined.