CONICET | Buscador de Institutos y Recursos Humanos

Over the last years several modified clay absorbents have been synthesized by loading the clays with organic compounds and iron oxides. The purpose is twofold, improve their adsorbent efficiency and confer the materials with permanent magnetization to facilitate an operator-free sludge handling by external magnetic fields. These clay-Fe oxides materials meet the requirements to be ecofriendly, efficient and cheap, particularly by the clay presence. A thorough characterization is needed to evaluate their sorption and magnetic properties. In addition to using conventional characterization techniques, Mössbauer spectroscopy has been applied with great advantage not only to identify the formed Fe phases on sorbent materials, their relative spectral area and the total Fe concentration, but also to study the influence of the supporting material on the formed Fe phases and magnetic response.In this poster, three examples show the gain that the use of Mössbauer spectroscopy has brought about. The syntheses of Fe oxide by means of alkaline oxidation on montmorillonite (Mt), organically modified montmorillonite (OMt) with hexadecyltrimethylammonium bromide(HDTMA) and beidellite clays let obtain sorbent materials with different magnetite and goethite concentrations, as well as magnetite with different degrees of oxidation. Particularly, the inclusion of HDTMA on Mt avoided the incorporation of Fe atoms onto Mt, favoring the formation of nano-Fe oxides, which enables absorbing successfully Co, dyes and arsenic. Besides, the use of beidellite clays with different cation exchange capacity and surface area permitted to obtain magnetic materials with different properties for Sr and Cs sorption. In all the cases, the Fe oxides presence does not decrease the adsorption or sorption capacity of the materials in comparison to the nonmagnetic variants.

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