Utilização de um rejeito de minerio de ferro para a produção de nanomateriais de carbono em leito fluidizado e aplicação desses materiais na adsorção de um contaminante emergente

Abstract

The present work reports the use of iron ore tailings as a catalyst and support for the production of carbon nanomaterials (CNMs) and their application in the adsorption of the 17-Ethinylestradiol (EE) hormone. The synthesis was carried out by means of the CVD (Chemical Vapor Deposition) technique in a Fluidized Bed (FB) type oven. Thegrowth of NMCs occurred from two sources of carbon: ethylene at temperatures of 500, 600 and 700 ° C, and acetonitrile at 500, 600, 700, 800 and 900 ° C. Two classes of different materials were obtained. The transmission electron microscopy (TEM) results showed that the two higher temperatures in each case favored the formation ofnanostructures of the type carbon nanotubes (CNTs), with good yields. The ethylene source generated classic tubular structures of multiple walls. On the other hand, acetonitrile provided the formation of pipes with less organization, known as bamboo like. This morphology was caused by the insertion of nitrogen into the graphite structure (doping), which originates from the carbon source. In fact, by Raman spectroscopy theethylene materials were better structured because they presented higher intensities for the G band in relation to the D band. When compared to other works in the literature, the adsorptive capacity of the materials for 17-Ethinylestradiol showed positive, ranging from 9.2 mg g-1 to 22.3 mg g-1.The kinetic and adsorption isotherm studies were also performed for the systems. As for kinetics, all of them present pseudosecond order behavior. Therefore, the speed of reactions depends on both theconcentration of the hormone and the mass of the material. In relation to the type of isotherm, the systems showed Freundlich behavior, that is, the adsorption occurs in multiple layers. Finally, it was concluded that the use of an iron ore tail as a catalyst in the production of CNMs by CVD is feasible. The materials synthesized still had good adsorptive capacity for an emerging contaminant. Thus, this study allowed the investigation of two environmental problems.