Abstract

SILVA, Gabriela Cordeiro; ALMEIDA, Fabiana Soares; FERREIRA, Angela Melo  and  CIMINELLI, Virginia Sampaio Teixeira. Preparation and application of a magnetic composite (Mn₃O₄/Fe₃O₄) for removal of As(III) from aqueous solutions. Mat. Res. [online]. 2012, vol.15, n.3, pp. 403-408.  Epub Apr 05, 2012. ISSN 1516-1439.  http://dx.doi.org/10.1590/S1516-14392012005000041.

The introduction of magnetic properties in adsorbent materials has the aim of improving solid-liquid separation processes. In this work, a magnetic composite was synthesized through the precipitation of manganese oxide in the presence of magnetite particles using O₂ as an oxidant. The composite proved to be chemically and physically stable within a wide range of pH values. The composite characterization indicated that hausmannite (Mn₃O₄) represents the precipitated manganese phase and that magnetite undergoes no phase transformation during the synthesis. The composite and Mn₃O₄ particles were used to remove As(III) from aqueous solutions. The magnetic composite and Mn₃O₄ sample presented high and similar affinity for As(III), with maximum sorptive capacities of 14 mg_As g_solid^-1 (0.0048 mmol_As m^-2_solid) and 20 mg_As g_solid^-1 (0.0049 mmol_As m^-2_solid), respectively, at pH 5.0. The combination of an active high surface area sorbent (Mn₃O₄) with a magnetic phase (Fe₃O₄) allows for efficient As(III) removal and solid/liquid separation.

Keywords : magnetic composite; manganese oxide; arsenic; adsorption.