Banca de QUALIFICAÇÃO: MICHAEL SEGUNDO SENA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : MICHAEL SEGUNDO SENA
DATA : 10/08/2016
HORA: 14:00
LOCAL: AUDITÓRIO DO PPGEQ
TÍTULO:

"Synthesis and characterization of Cerium Molybdate obtained by the method of combined complexation EDTA/Citrate applied in the Methylene Blue photocatalysis."

PALAVRAS-CHAVES:

Cerium Molybdtae, Synthesis, EDTA/Citrate, Experimental Planning, Photocatalysis, Methylene Blue.

PÁGINAS: 98
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Química
RESUMO:

In this work, Cerium Molybdate (Ce₂(MoO₄)₃) was synthesized and characterized, obtained by the method of combined complexation EDTA/Citrate, the synthesis parameters were investigated to evaluate the influence of pH (5, 7,5 and 10), calcining time (3, 4 and 5h) and heating rate (5, 7 and 10°C.min^-1)  on phase formation, average crystallite size and the material band gap. The samples obtained were characterized by TG/DSC, XRD, EDX, SEM and DRS analysis. The TG/DSC analysis curve shows that volatiles decomposition happens until 600°C, this temperature was chosen to calcine the precursors. The XRD patterns of the samples were all indexed to JCPDS (Joint Committee on Powder Diffraction Standards) card no. 01-070-1382 with a single-phase monoclinic structure of Scheelite type and space group C2/c, secondary phases were not identified. The XRD patterns were refined by the Rietveld method, where the lattice parameters were obtained. The EDX analysis (weight %) showed no significant differences between the proportions of Mo and Ce among the synthesized samples. The SEM images show that in general powders are formed by large agglomerated particles with rounded shape, forming a porous material. The study of average crystallite size was done by the interpretation of the data of the estimated diffraction patterns by the methods of Halder-Wagner-Langford (HWL) and Scherrer. The optical properties of nanoparticles were evaluated using the DRS-UV/Vis analysis whereby the optical band gap were reported, being classified as semiconductor materials with potential photocatalytic application using visible light as radiation source. An experimental design 2³ with three replications in central point was performed and the effects of synthesis parameters in crystallite size and value of the band gap were evaluated. The synthesis method used was efficient for the production of a crystalline, single phase and nanosized material. The photocatalysis tests show that the presence of the catalyst has a positive effect on the degradation of methylene blue dye in solution.

MEMBROS DA BANCA:
Externo ao Programa - 2929066 - ANDRE LUIS LOPES MORIYAMA
Externo à Instituição - ANGÉLICA BELCHIOR VITAL - UFRN
Presidente - 349801 - CARLSON PEREIRA DE SOUZA
Externo ao Programa - 338292 - JOÃO BOSCO LUCENA DE OLIVEIRA