Preparation of new adsorbents for pertechnate adsorption

Authors: Eva Viglašová 1    Martin Daňo 2    Michal Galamboš 1    Pavol Rajec 2   
1 Comenius University, Faculty of Natural Sciences, Department of Inorganic chemistry    2 Comenius University, Faculty of Natural Sciences, Department of Nuclear chemistry   
Year: 2015
Section: Ecology and Environmental Sciences
Abstract No.: 1198
ISBN: 978-80-970712-8-8

Activated carbon (AC) is a solid, porous, black carbonaceous material. It is distinguished from elemental carbon by the absence of both impurities and an oxidized surface. The specific properties of AC depend on both the source of the organic material (usually biomass material such as wood, peat, lignite, oil products or coal) and treatment method—typically a two-stage process: carbonization followed by activation. AC is produced in various forms, including powders, cylindrical extrudates, spherical beads, granules and fibres. The most important property of AC, the property that determines its possible application, is its porous structure. The total number of pores, their shape and size determine the adsorption capacity and even the dynamic adsorption rate of AC. Due to its nanoporous structure, highspecific surface area, and variable surface functional groups, AC is widely used as an adsorbent for removing radionuclides and toxic metals, oxyanions, and organic compounds [1]. Technetium was predicted in 1897 by Mendeleev and discovered in 1935 by Perrier and Segrè. It was the first man-made element. All isotopes of technetium are radioactive. Technetium-99 is a β-emitting fission product with a long half-life of 2.13 x 105 years [2]. It is formed in the thermal neutron fission of 235U with high yield 6.13 % in energetic nuclear reactors. The fate of this radionuclide released from spent fuel alternation is of particular concern in the performance assessment of high-level waste repositories [3]. Tc may exist in different oxidation states, depending on redox conditions. Under oxidizing conditions, the predominant stable chemical form is pertechnetate anion (TcVIIO4-), which is generally highly soluble and mobile. Under reducing conditions, Tc(IV) hydro- or hydrated oxides, TcO(OH)2 or TcO2·nH2O (n = 1, 2), are formed and they are soluble sparingly. So, the redox conditions have an important effect on the migration of Tc in a waste repository and in the biosphere [4].  The main aim of this research was to prepare new activated carbon materials, characterize them and test their capabilities for removing TcO4-.

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[3]  Desmet G, Myttenaere C (1986) Technetium in the environment. Elsevier, Amsterdam
[4]  El-Wear S, German KE, Peretrukhin VF (1992) Sorption of technetium on inorganic sorbents and natural minerals. J Radioanal Nucl Chem 157(1):3–14