Banca de QUALIFICAÇÃO: JAILTON ALVES DE VASCONCELOS JUNIOR

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JAILTON ALVES DE VASCONCELOS JUNIOR
DATE: 22/09/2022
TIME: 14:00
LOCAL: Google Meet
TITLE:

SYNTHESIS AND APPLICATIONS OF THE OXIDES SiO2-ZrO2AND SiO2-ZrO2-BaO OBTAINED BY THE METHODS OF PECHINI AND METAL-CHITOSAN COMPLEXATION.

KEY WORDS:

mixed oxides, chromatography, photocatalysis, glycerol.

PAGES: 70
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

The modification of silica has been an alternative to improve some properties on this material, such as the insertion of other metallic oxides, providing greater chemical and mechanical resistance. In this work, the modification of silica was carried out, aiming at its use in liquid chromatography, as well as the application of the oxides in photocatalysis, with the oxides ZrO2and BaO, by the modified Pechini method (MPE), using glycerol as polyol, and by metal-chitosan complexation (CMQ),in order to give better properties to the final material. The oxides SiO2-ZrO2(SZ) and SiO2-ZrO2-BaO (SZB) were synthesized by both methods. For use in chromatography, glycerol was added to the surface of the oxides. To elucidate the structural and textural properties of these materials, they were characterized by thermogravimetric analysis (TGA), infrared absorption spectroscopy (FTIR), analysis of nitrogen physisorption at 77 K (BET), X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDX) and diffuse ultraviolet reflectance spectroscopy (DRS). The TGA analyzes showed that the synthesized materials had an effective calcination, with the absence of organic matter and presented a good thermal resistance, without degradation and with mass lossesbetween 4 and 8%, referring to the loss of adsorbed water. In the FTIR analysis, the loss of signal at 800 cm-1(Fig. 1) present in pure silica was observed in the spectra, showing that there is a change in the Si-OH groups with the insertion of metals inthis bond. In the analysis of nitrogen Physisorption, by the BET method, a greater surface area was observed for the SZB oxide synthesized by the CMQ method (203 m2/g), whereas the SZ oxide presented a greater area when synthesized by the MPE method (335 m2/g), however the oxides synthesized by Pechini had a larger pore diameter. By XRD it was observed that the materials were amorphous. After the characterizations, the modification of silica with the oxides ZrO2and BaO was noticed, as well as a high surface area (335 m2/g) and high thermal and chemical resistance, characteristics that are important for the application of these materials in liquid chromatography. In the DRS analysis, a lower band gap value was observed for the oxides synthesized by CMQ, being 2.93 for the SZ-CMQ and 3.51 for the SZB-CMQ. After the addition of glycerol to silica, it was confirmed by FTIR, proving the efficiency of the synthesis method.

BANKING MEMBERS:
Externo ao Programa - 1545506 - ANTONIO OSIMAR SOUSA DA SILVA
Interna - 1314677 - CARMEM LUCIA DE PAIVA E SILVA ZANTA
Presidente - 1904678 - JANAINA HEBERLE BORTOLUZZI
Externa à Instituição - Lisiane dos Santos Freitas
Interno - 1348288 - MARIO ROBERTO MENEGHETTI
Interna - 1515173 - SIMONI MARGARETI PLENTZ MENEGHETTI
Externo ao Programa - 1488396 - TICIANO GOMES DO NASCIMENTO