Banca de DEFESA: YURI LEANDRO RODRIGUES LOPES FERNANDES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : YURI LEANDRO RODRIGUES LOPES FERNANDES
DATE: 13/04/2022
TIME: 07:30
LOCAL: SalaVirtual
TITLE:

 

Study, preparation and characterization of Diatomite/Nb2O5/TiO2 mesoporous
nanocomposites for the treatment of contaminated water

KEY WORDS:

 Keywords: Diatomite. Titanium dioxide. Niobium pentoxide. Filtration.

PAGES: 90
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

The emerging need for more efficient water treatment methods has become a
problem beyond the scientific character: it covers ethical, economic and social
issues. The advancement of the understanding about the mechanisms of filtration
and treatment of contaminated water by porous matrix composites, such as
diatomite, stimulated the development of this work. In this study, white diatomite
ceramic powder was used to fabricate porous composites incorporated by Nb2O5 and
TiO2 particles through the Tape Casting technique. Four ceramic-polymer tapes of
ceramic mass composition (diatomite/TiO2
/Nb2O5
) were obtained: tape a (1/0/0); tape

b (0.9/0.1/0); tape c (0.9/0.05/0.05); and tape d (0.9/0/0.1). Finally, six-layer
laminates were arranged, thermo-pressed, calcined at 500 oC and sintered at 1200
oC, giving rise to the A - E ceramic wafers. The thermal behavior of the tapes was
determined by thermogravimetric analysis (TG). Aiming to verify the effect of the
processing route and composition on the morphological characteristics, the
composition of crystalline phases, flexural strength, porosity profile and the
adsorptive and photodegradation properties, the wafers were characterized by X-ray
diffraction, field emission scanning electron microscopy, three-point bending test, N2
physisorption, photodegradation test and Egap determination aided by UV-vis
spectrophotometer. The resulting ceramic composites were found to have high
porosity morphologies and monolithic characters. The crystalline phases cristobalite,
quartz, anatase, rutile, and H-Nb2O5 were identified; by which an evolution of the
crystalline structure, elimination of the amorphous zone, as well as the partial
transformation of anatase-rutile phase was noted in wafers B and C. The bending
test demonstrated an increase of up to 225% in strength through incorporation of the
particles into the diatomite matrix, from 4.28 Mpa in wafer A to 13.90 Mpa in wafer C.
The wafers exhibited a mesoporous structure, with narrowing of the pore size
distribution and surface areas between 6.161 m2/g and 3.6 m2/g. A decomposition of
up to 87.3% of methylene blue was observed across the composites, whose Egap
values are in the range of 3.19 eV – 3.70 eV.

BANKING MEMBERS:
Presidente - 345842 - UILAME UMBELINO GOMES
Interno - 1300987 - CARLOS ALBERTO PASKOCIMAS
Externo ao Programa - 2414250 - MEYSAM MASHHADIKARIMI
Externa à Instituição - ARIADNE DE SOUZA SILVA