Navegando por Palavras-chave "Manganese Dioxide"

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    Síntese de nanopartículas de óxidos de manganês em líquidos iônicos e sua imobilização em celulose
    (Universidade Federal de São Paulo (UNIFESP), 2021) Oliveira, Larissa Verena Figueiredo De [UNIFESP]; Camilo, Fernanda Ferraz [UNIFESP]; Universidade Federal de São Paulo
    The development of synthetic methodologies for manganese oxide nanomaterials has been the subject of several studies due to the improved physical and chemical properties of these materials compared to those in micro and macro scales and their wide applicability. In this thesis, it was developed a new preparation method of MnO 2 nanoparticles in an exclusive medium of different ionic liquids, which acted simultaneously as a solvent, structure-directing agent, and reducing agent of a permanganate salt, the tetramethylammonium permanganate (TMAMnO 4 ). The synthesis was performed in a single step and under mild conditions. It was obtained, for all ionic liquids tested, MnO 2 in nanoscale with lamellar structural organization and with the cations of the ionic liquids in the interlamellar space. These materials were immobilized on non-modified cellulose films and used in discoloration tests of Indigo Carmine dye (IC). The immobilization of the nanoparticles at the films prevented the aggregation and/or agglomeration of the particles during use and it facilitated its recovery from the reaction medium and reuse for several cycles. The obtained films were amorphous and had around 5 wt.% of MnO 2 nanoparticles distributed homogeneously in the cellulosic film. These films were capable of efficiently discoloring an Indigo Carmine dye solution, decolorizing 5.00 mL of a 20 ppm IC solution between 35-50 minutes, depending on the film used. Besides, they could be reused for at least 5 cycles without significant loss of efficiency. These materials were easily removed from the solution using a tweezer. The use of a film instead of dispersion or powdered material allows straightforward isolation from treated water, avoiding the need for more complex separation methods, such as centrifugation or filtration.