Banca de QUALIFICAÇÃO: RONALDO DOS SANTOS FALCÃO FILHO

OBTAINING PHOTOCATALYTIC CERAMIC MATERIALS OF Nb2O5 IMMOBILIZED ON RED CERAMIC SUPPORTS FOR REMOVAL OF CONTAMINANTS FROM EFFLUENTS

Photocatalysis. Environment pollution. Wastewater treatment.

The objective of this work was to produce ceramic materials with photocatalytic property of Nb2O5 immobilized on a red ceramic support capable of removing micropollutants from synthetic effluents. For this purpose, two different types of ceramic materials were produced: in the first type, Nb2O5, in different proportions ranging from 10.8% to 19.2%, was incorporated into treated common clay and the mixture was homogenized with water to form a plastic mass that was moulded, dried and, finally, the materials were thermally treated at temperatures between 850°C and 1020°C; in the second type, the photocatalytic material was produced by applying a coating with 60% Nb2O5 on a red ceramic support, which was prepared similarly to the first type, but was only fired at 850° C. The materials were characterized by granulometric analysis, hygroscopic humidity, FRX, DRX, SEM, ERD, ATG, PCZ, technological properties. A DCCR-type experimental design with 22 factorial runs, 2.2 axial runs and 2 runs at the central point was used to choose the material with incorporated Nb2O5, using methylene blue (AM) dye removal as a response variable, thus, the material produced with 15% Nb2O5 and a burning temperature of 850° C was chosen because it removes 80.26% of the AM concentration. In the case of the material coated with 60% Nb2O5, as it was the only one, it was evaluated for AM removal as a function of the pH (5, 7 and 9) and [H2O2] (0, 50 and 100 mg/L) variables, in this case, a planning of the DCC-FC type was used with 22 factorial runs, 2.2 axial runs and 2 runs at the central point, the evaluation of the obtained model showed that the variable [H2O2] was not significant, in the range studied, and the Optimal pH for AM removal was 8.0. The material with incorporated Nb2O5 presented Eg = 1.95 eV and the one with 60% Nb2O5 coating presented Eg = 2.94 eV. In addition, both types of materials showed excellent regeneration capabilities after 5 cycles, maintaining removals close to 90%. The photocatalytic materials produced with Nb2O5 immobilized on red ceramic supports showed the ability to remove AM in synthetic effluent, with the material coated with Nb2O5 promising because it presents Eg close to that of the pure oxide, simplicity of obtaining, high removal and recovery capacities.