Banca de QUALIFICAÇÃO: MONICKARLA TEIXEIRA PEGADO DA SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MONICKARLA TEIXEIRA PEGADO DA SILVA
DATE: 16/12/2019
TIME: 14:00
LOCAL: Auditório do CCET
TITLE:

Synthesis of Fe2SiO4-Fe7Co3 based nanocomposites dispersed in SBA-15 ratio: Application as magnetically separable adsorbent

KEY WORDS:

magnetic nanocomposite, Fe₇Co₃ alloy, Fe₂SiO₄ oxide, adsorption, dyes.

PAGES: 84
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Cinética Química e Catálise
SUMMARY:

The present study describes the synthesis of a new type of Fe₂SiO₄-Fe₇Co₃ based nanocomposite dispersed in mesoporous SBA-15 aiming to apply the dyes adsorption following their magnetic separation. A study was presented varying the reduction temperature and amount of hydrogen used in the synthesis and how these parameters affect the physicochemical properties of the oxide-alloy mixture with iron and cobalt, as well as the adsorption capacity of methylene blue. The solids were characterized by X-ray diffraction (XRD), Mössbauer (MS) spectroscopy, X-ray photoelectron spectroscopy (XPS), vibratory sample magnetometry (VSM), programmed temperature reduction (H2-TPR), adsorption and N2 desorption, Scanning electron microscopy (SEM-FEG) and Transmission electron microscopy (TEM). The XRD results together with the TPR profiles confirmed the formation of Fe₂SiO₄-Fe₇Co₃ -based nanocomposites at temperatures between 690 and 720 ° C and flows between 0.5 and 2% H2. The increase of the reduction temperature and the increase of H2 content in the reduction mixture led to the formation of a higher amount of alloy in relation to the oxide according to the data obtained by the Rietveld refinement. Low-angle XRD, N2 isotherms, and TEM images show the formation of the SBA-15-based mesoporous support with a high specific surface area. However, the surface area and mesoporous structure of the silica was slightly altered after Fe and Co insertion due to partial pore filling by the composite. Adsorption tests confirmed that the material reduced to 700 ° C using 2% H2 had the highest adsorption capacity for methylene blue (AM) dye. The nanocomposites obtained have good adsorption capacity for AM dye and can be easily separated from the final dispersion by applying an external magnetic field after adsorption, which was confirmed by VSM analysis. The attraction of the dye to the nanocomposite occurs mainly by π-π interactions and the mixing of Fe₂SiO₄ and Fe₇Co₃ phases leads to a synergistic effect which favor the methylene blue adsorption process compared to the same isolated phases.

BANKING MEMBERS:
Externo ao Programa - 007.843.440-86 - EDUARDO RIGOTI - UFRN
Externo ao Programa - 1508681 - FELIPE BOHN
Interna - 1308577 - SIBELE BERENICE CASTELLA PERGHER
Presidente - 2087667 - TIAGO PINHEIRO BRAGA
Externo à Instituição - VINÍCIUS PATRÍCIO DA SILVA CALDEIRA - UERN