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Title: Cellulose nanocrystals assembled on the Fe3O4 surface as precursor to prepare interfaced C/Fe3O4 composites for the oxidation of aqueous sulfde
Title of periodic: Journal of the Brazilian Chemical Society
Authors: Cunha, Igor T.
Teixeira, Ivo F.
Mesquita, João Paulo de
Ardisson, José Domingos
Binatti, Ildefonso Ildefonso
Pereira, Fabiano Vargas
Lago, Rochel Montero
Affiliation: Universidade Federal de Minas Gerais, UFMG, Belo Horizonte, MG, Brasil
University of Oxford, Oxford, United Kingdom
Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina, MG, Brasil
Centro de Desenvolvimento da Tecnologia Nuclear, CDTN, Belo Horizonte, MG, Brasil
Centro Federal de Educação Tecnológica de Minas Gerais, CEFET, Belo Horizonte, Brasil
Universidade Federal de Minas Gerais, UFMG, Belo Horizonte, MG, Brasil
Universidade Federal de Minas Gerais, UFMG, Belo Horizonte, MG, Brasil
Issue Date: 2016
Keywords: Cellulose;Microscopy;Nanostructure
Abstract: In this work, composites based on carbon (1, 10 and 20 wt.%) interfaced with Fe3O4 (magnetite) have been studied as catalysts for the oxidation of aqueous sulfde. The composites were prepared by assembling cellulose nanocrystals surrounding Fe3O4 followed by a controlled thermal decomposition at 400, 600 and 800 °C. Mössbauer, X-ray diffractometry (XRD), Raman, thermogravimetry (TG), elemental analysis CHN, scanning electron microscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR) and potentiometric titration indicated that at 400 and 600 °C the cellulose nanocrystals decompose to different carbon forms, i.e., flms, flaments and particles attached to the Fe3O4 crystals. At higher temperature, i.e., 800 °C, this carbon on the magnetite surface further reacted to produce Fe0. UV-Vis, Raman and electrospray ionization mass spectrometry (ESI-MS) measurements showed that these composites catalyze the oxidation of aqueous sulfde to convert S2- aq to polysulfdes Sn 2- (where n = 2-9) and also oxygen containing polysulfdes HOSn -. Simple kinetic experiments showed very low sulfde oxidation activities for pure Fe3O4 and pure carbon. On the other hand, the composites, especially with 10% C obtained at 600 °C, were remarkably active. These results are discussed in terms of a possible participation of oxygen based redox groups present on the carbon surface and an electron transfer from the carbon to the Fe3O4 phase.
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